AI Skillbase Archiv

---
name: webapp-testing
description: Toolkit for interacting with and testing local web applications using Playwright. Supports verifying frontend functionality, debugging UI behavior, capturing browser screenshots, and viewing browser logs.
license: Complete terms in LICENSE.txt
---

# Web Application Testing

To test local web applications, write native Python Playwright scripts.

**Helper Scripts Available**:
- `scripts/with_server.py` - Manages server lifecycle (supports multiple servers)

**Always run scripts with `--help` first** to see usage. DO NOT read the source until you try running the script first and find that a customized solution is abslutely necessary. These scripts can be very large and thus pollute your context window. They exist to be called directly as black-box scripts rather than ingested into your context window.

## Decision Tree: Choosing Your Approach

```
User task → Is it static HTML?
    ├─ Yes → Read HTML file directly to identify selectors
    │         ├─ Success → Write Playwright script using selectors
    │         └─ Fails/Incomplete → Treat as dynamic (below)
    │
    └─ No (dynamic webapp) → Is the server already running?
        ├─ No → Run: python scripts/with_server.py --help
        │        Then use the helper + write simplified Playwright script
        │
        └─ Yes → Reconnaissance-then-action:
            1. Navigate and wait for networkidle
            2. Take screenshot or inspect DOM
            3. Identify selectors from rendered state
            4. Execute actions with discovered selectors
```

## Example: Using with_server.py

To start a server, run `--help` first, then use the helper:

**Single server:**
```bash
python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py
```

**Multiple servers (e.g., backend + frontend):**
```bash
python scripts/with_server.py \
  --server "cd backend && python server.py" --port 3000 \
  --server "cd frontend && npm run dev" --port 5173 \
  -- python your_automation.py
```

To create an automation script, include only Playwright logic (servers are managed automatically):
```python
from playwright.sync_api import sync_playwright

with sync_playwright() as p:
    browser = p.chromium.launch(headless=True) # Always launch chromium in headless mode
    page = browser.new_page()
    page.goto('http://localhost:5173') # Server already running and ready
    page.wait_for_load_state('networkidle') # CRITICAL: Wait for JS to execute
    # ... your automation logic
    browser.close()
```

## Reconnaissance-Then-Action Pattern

1. **Inspect rendered DOM**:
   ```python
   page.screenshot(path='/tmp/inspect.png', full_page=True)
   content = page.content()
   page.locator('button').all()
   ```

2. **Identify selectors** from inspection results

3. **Execute actions** using discovered selectors

## Common Pitfall

❌ **Don't** inspect the DOM before waiting for `networkidle` on dynamic apps
✅ **Do** wait for `page.wait_for_load_state('networkidle')` before inspection

## Best Practices

- **Use bundled scripts as black boxes** - To accomplish a task, consider whether one of the scripts available in `scripts/` can help. These scripts handle common, complex workflows reliably without cluttering the context window. Use `--help` to see usage, then invoke directly. 
- Use `sync_playwright()` for synchronous scripts
- Always close the browser when done
- Use descriptive selectors: `text=`, `role=`, CSS selectors, or IDs
- Add appropriate waits: `page.wait_for_selector()` or `page.wait_for_timeout()`

## Reference Files

- **examples/** - Examples showing common patterns:
  - `element_discovery.py` - Discovering buttons, links, and inputs on a page
  - `static_html_automation.py` - Using file:// URLs for local HTML
  - `console_logging.py` - Capturing console logs during automation
FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:examples/console_logging.py
from playwright.sync_api import sync_playwright

# Example: Capturing console logs during browser automation

url = 'http://localhost:5173'  # Replace with your URL

console_logs = []

with sync_playwright() as p:
    browser = p.chromium.launch(headless=True)
    page = browser.new_page(viewport={'width': 1920, 'height': 1080})

    # Set up console log capture
    def handle_console_message(msg):
        console_logs.append(f"[{msg.type}] {msg.text}")
        print(f"Console: [{msg.type}] {msg.text}")

    page.on("console", handle_console_message)

    # Navigate to page
    page.goto(url)
    page.wait_for_load_state('networkidle')

    # Interact with the page (triggers console logs)
    page.click('text=Dashboard')
    page.wait_for_timeout(1000)

    browser.close()

# Save console logs to file
with open('/mnt/user-data/outputs/console.log', 'w') as f:
    f.write('\n'.join(console_logs))

print(f"\nCaptured {len(console_logs)} console messages")
print(f"Logs saved to: /mnt/user-data/outputs/console.log")
FILE:examples/element_discovery.py
from playwright.sync_api import sync_playwright

# Example: Discovering buttons and other elements on a page

with sync_playwright() as p:
    browser = p.chromium.launch(headless=True)
    page = browser.new_page()

    # Navigate to page and wait for it to fully load
    page.goto('http://localhost:5173')
    page.wait_for_load_state('networkidle')

    # Discover all buttons on the page
    buttons = page.locator('button').all()
    print(f"Found {len(buttons)} buttons:")
    for i, button in enumerate(buttons):
        text = button.inner_text() if button.is_visible() else "[hidden]"
        print(f"  [{i}] {text}")

    # Discover links
    links = page.locator('a[href]').all()
    print(f"\nFound {len(links)} links:")
    for link in links[:5]:  # Show first 5
        text = link.inner_text().strip()
        href = link.get_attribute('href')
        print(f"  - {text} -> {href}")

    # Discover input fields
    inputs = page.locator('input, textarea, select').all()
    print(f"\nFound {len(inputs)} input fields:")
    for input_elem in inputs:
        name = input_elem.get_attribute('name') or input_elem.get_attribute('id') or "[unnamed]"
        input_type = input_elem.get_attribute('type') or 'text'
        print(f"  - {name} ({input_type})")

    # Take screenshot for visual reference
    page.screenshot(path='/tmp/page_discovery.png', full_page=True)
    print("\nScreenshot saved to /tmp/page_discovery.png")

    browser.close()
FILE:examples/static_html_automation.py
from playwright.sync_api import sync_playwright
import os

# Example: Automating interaction with static HTML files using file:// URLs

html_file_path = os.path.abspath('path/to/your/file.html')
file_url = f'file://{html_file_path}'

with sync_playwright() as p:
    browser = p.chromium.launch(headless=True)
    page = browser.new_page(viewport={'width': 1920, 'height': 1080})

    # Navigate to local HTML file
    page.goto(file_url)

    # Take screenshot
    page.screenshot(path='/mnt/user-data/outputs/static_page.png', full_page=True)

    # Interact with elements
    page.click('text=Click Me')
    page.fill('#name', 'John Doe')
    page.fill('#email', 'john@example.com')

    # Submit form
    page.click('button[type="submit"]')
    page.wait_for_timeout(500)

    # Take final screenshot
    page.screenshot(path='/mnt/user-data/outputs/after_submit.png', full_page=True)

    browser.close()

print("Static HTML automation completed!")
FILE:scripts/with_server.py
#!/usr/bin/env python3
"""
Start one or more servers, wait for them to be ready, run a command, then clean up.

Usage:
    # Single server
    python scripts/with_server.py --server "npm run dev" --port 5173 -- python automation.py
    python scripts/with_server.py --server "npm start" --port 3000 -- python test.py

    # Multiple servers
    python scripts/with_server.py \
      --server "cd backend && python server.py" --port 3000 \
      --server "cd frontend && npm run dev" --port 5173 \
      -- python test.py
"""

import subprocess
import socket
import time
import sys
import argparse

def is_server_ready(port, timeout=30):
    """Wait for server to be ready by polling the port."""
    start_time = time.time()
    while time.time() - start_time < timeout:
        try:
            with socket.create_connection(('localhost', port), timeout=1):
                return True
        except (socket.error, ConnectionRefusedError):
            time.sleep(0.5)
    return False


def main():
    parser = argparse.ArgumentParser(description='Run command with one or more servers')
    parser.add_argument('--server', action='append', dest='servers', required=True, help='Server command (can be repeated)')
    parser.add_argument('--port', action='append', dest='ports', type=int, required=True, help='Port for each server (must match --server count)')
    parser.add_argument('--timeout', type=int, default=30, help='Timeout in seconds per server (default: 30)')
    parser.add_argument('command', nargs=argparse.REMAINDER, help='Command to run after server(s) ready')

    args = parser.parse_args()

    # Remove the '--' separator if present
    if args.command and args.command[0] == '--':
        args.command = args.command[1:]

    if not args.command:
        print("Error: No command specified to run")
        sys.exit(1)

    # Parse server configurations
    if len(args.servers) != len(args.ports):
        print("Error: Number of --server and --port arguments must match")
        sys.exit(1)

    servers = []
    for cmd, port in zip(args.servers, args.ports):
        servers.append({'cmd': cmd, 'port': port})

    server_processes = []

    try:
        # Start all servers
        for i, server in enumerate(servers):
            print(f"Starting server {i+1}/{len(servers)}: {server['cmd']}")

            # Use shell=True to support commands with cd and &&
            process = subprocess.Popen(
                server['cmd'],
                shell=True,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE
            )
            server_processes.append(process)

            # Wait for this server to be ready
            print(f"Waiting for server on port {server['port']}...")
            if not is_server_ready(server['port'], timeout=args.timeout):
                raise RuntimeError(f"Server failed to start on port {server['port']} within {args.timeout}s")

            print(f"Server ready on port {server['port']}")

        print(f"\nAll {len(servers)} server(s) ready")

        # Run the command
        print(f"Running: {' '.join(args.command)}\n")
        result = subprocess.run(args.command)
        sys.exit(result.returncode)

    finally:
        # Clean up all servers
        print(f"\nStopping {len(server_processes)} server(s)...")
        for i, process in enumerate(server_processes):
            try:
                process.terminate()
                process.wait(timeout=5)
            except subprocess.TimeoutExpired:
                process.kill()
                process.wait()
            print(f"Server {i+1} stopped")
        print("All servers stopped")


if __name__ == '__main__':
    main()
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/webapp-testing
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: web-artifacts-builder
description: Suite of tools for creating elaborate, multi-component claude.ai HTML artifacts using modern frontend web technologies (React, Tailwind CSS, shadcn/ui). Use for complex artifacts requiring state management, routing, or shadcn/ui components - not for simple single-file HTML/JSX artifacts.
license: Complete terms in LICENSE.txt
---

# Web Artifacts Builder

To build powerful frontend claude.ai artifacts, follow these steps:
1. Initialize the frontend repo using `scripts/init-artifact.sh`
2. Develop your artifact by editing the generated code
3. Bundle all code into a single HTML file using `scripts/bundle-artifact.sh`
4. Display artifact to user
5. (Optional) Test the artifact

**Stack**: React 18 + TypeScript + Vite + Parcel (bundling) + Tailwind CSS + shadcn/ui

## Design & Style Guidelines

VERY IMPORTANT: To avoid what is often referred to as "AI slop", avoid using excessive centered layouts, purple gradients, uniform rounded corners, and Inter font.

## Quick Start

### Step 1: Initialize Project

Run the initialization script to create a new React project:
```bash
bash scripts/init-artifact.sh <project-name>
cd <project-name>
```

This creates a fully configured project with:
- ✅ React + TypeScript (via Vite)
- ✅ Tailwind CSS 3.4.1 with shadcn/ui theming system
- ✅ Path aliases (`@/`) configured
- ✅ 40+ shadcn/ui components pre-installed
- ✅ All Radix UI dependencies included
- ✅ Parcel configured for bundling (via .parcelrc)
- ✅ Node 18+ compatibility (auto-detects and pins Vite version)

### Step 2: Develop Your Artifact

To build the artifact, edit the generated files. See **Common Development Tasks** below for guidance.

### Step 3: Bundle to Single HTML File

To bundle the React app into a single HTML artifact:
```bash
bash scripts/bundle-artifact.sh
```

This creates `bundle.html` - a self-contained artifact with all JavaScript, CSS, and dependencies inlined. This file can be directly shared in Claude conversations as an artifact.

**Requirements**: Your project must have an `index.html` in the root directory.

**What the script does**:
- Installs bundling dependencies (parcel, @parcel/config-default, parcel-resolver-tspaths, html-inline)
- Creates `.parcelrc` config with path alias support
- Builds with Parcel (no source maps)
- Inlines all assets into single HTML using html-inline

### Step 4: Share Artifact with User

Finally, share the bundled HTML file in conversation with the user so they can view it as an artifact.

### Step 5: Testing/Visualizing the Artifact (Optional)

Note: This is a completely optional step. Only perform if necessary or requested.

To test/visualize the artifact, use available tools (including other Skills or built-in tools like Playwright or Puppeteer). In general, avoid testing the artifact upfront as it adds latency between the request and when the finished artifact can be seen. Test later, after presenting the artifact, if requested or if issues arise.

## Reference

- **shadcn/ui components**: https://ui.shadcn.com/docs/components
FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:scripts/bundle-artifact.sh
#!/bin/bash
set -e

echo "📦 Bundling React app to single HTML artifact..."

# Check if we're in a project directory
if [ ! -f "package.json" ]; then
  echo "❌ Error: No package.json found. Run this script from your project root."
  exit 1
fi

# Check if index.html exists
if [ ! -f "index.html" ]; then
  echo "❌ Error: No index.html found in project root."
  echo "   This script requires an index.html entry point."
  exit 1
fi

# Install bundling dependencies
echo "📦 Installing bundling dependencies..."
pnpm add -D parcel @parcel/config-default parcel-resolver-tspaths html-inline

# Create Parcel config with tspaths resolver
if [ ! -f ".parcelrc" ]; then
  echo "🔧 Creating Parcel configuration with path alias support..."
  cat > .parcelrc << 'EOF'
{
  "extends": "@parcel/config-default",
  "resolvers": ["parcel-resolver-tspaths", "..."]
}
EOF
fi

# Clean previous build
echo "🧹 Cleaning previous build..."
rm -rf dist bundle.html

# Build with Parcel
echo "🔨 Building with Parcel..."
pnpm exec parcel build index.html --dist-dir dist --no-source-maps

# Inline everything into single HTML
echo "🎯 Inlining all assets into single HTML file..."
pnpm exec html-inline dist/index.html > bundle.html

# Get file size
FILE_SIZE=$(du -h bundle.html | cut -f1)

echo ""
echo "✅ Bundle complete!"
echo "📄 Output: bundle.html ($FILE_SIZE)"
echo ""
echo "You can now use this single HTML file as an artifact in Claude conversations."
echo "To test locally: open bundle.html in your browser"
FILE:scripts/init-artifact.sh
#!/bin/bash

# Exit on error
set -e

# Detect Node version
NODE_VERSION=$(node -v | cut -d'v' -f2 | cut -d'.' -f1)

echo "🔍 Detected Node.js version: $NODE_VERSION"

if [ "$NODE_VERSION" -lt 18 ]; then
  echo "❌ Error: Node.js 18 or higher is required"
  echo "   Current version: $(node -v)"
  exit 1
fi

# Set Vite version based on Node version
if [ "$NODE_VERSION" -ge 20 ]; then
  VITE_VERSION="latest"
  echo "✅ Using Vite latest (Node 20+)"
else
  VITE_VERSION="5.4.11"
  echo "✅ Using Vite $VITE_VERSION (Node 18 compatible)"
fi

# Detect OS and set sed syntax
if [[ "$OSTYPE" == "darwin"* ]]; then
  SED_INPLACE="sed -i ''"
else
  SED_INPLACE="sed -i"
fi

# Check if pnpm is installed
if ! command -v pnpm &> /dev/null; then
  echo "📦 pnpm not found. Installing pnpm..."
  npm install -g pnpm
fi

# Check if project name is provided
if [ -z "$1" ]; then
  echo "❌ Usage: ./create-react-shadcn-complete.sh <project-name>"
  exit 1
fi

PROJECT_NAME="$1"
SCRIPT_DIR="$(cd "$(dirname "BASH_SOURCE[0]")" && pwd)"
COMPONENTS_TARBALL="$SCRIPT_DIR/shadcn-components.tar.gz"

# Check if components tarball exists
if [ ! -f "$COMPONENTS_TARBALL" ]; then
  echo "❌ Error: shadcn-components.tar.gz not found in script directory"
  echo "   Expected location: $COMPONENTS_TARBALL"
  exit 1
fi

echo "🚀 Creating new React + Vite project: $PROJECT_NAME"

# Create new Vite project (always use latest create-vite, pin vite version later)
pnpm create vite "$PROJECT_NAME" --template react-ts

# Navigate into project directory
cd "$PROJECT_NAME"

echo "🧹 Cleaning up Vite template..."
$SED_INPLACE '/<link rel="icon".*vite\.svg/d' index.html
$SED_INPLACE 's/<title>.*<\/title>/<title>'"$PROJECT_NAME"'<\/title>/' index.html

echo "📦 Installing base dependencies..."
pnpm install

# Pin Vite version for Node 18
if [ "$NODE_VERSION" -lt 20 ]; then
  echo "📌 Pinning Vite to $VITE_VERSION for Node 18 compatibility..."
  pnpm add -D vite@$VITE_VERSION
fi

echo "📦 Installing Tailwind CSS and dependencies..."
pnpm install -D tailwindcss@3.4.1 postcss autoprefixer @types/node tailwindcss-animate
pnpm install class-variance-authority clsx tailwind-merge lucide-react next-themes

echo "⚙️  Creating Tailwind and PostCSS configuration..."
cat > postcss.config.js << 'EOF'
export default {
  plugins: {
    tailwindcss: {},
    autoprefixer: {},
  },
}
EOF

echo "📝 Configuring Tailwind with shadcn theme..."
cat > tailwind.config.js << 'EOF'
/** @type {import('tailwindcss').Config} */
module.exports = {
  darkMode: ["class"],
  content: [
    "./index.html",
    "./src/**/*.{js,ts,jsx,tsx}",
  ],
  theme: {
    extend: {
      colors: {
        border: "hsl(var(--border))",
        input: "hsl(var(--input))",
        ring: "hsl(var(--ring))",
        background: "hsl(var(--background))",
        foreground: "hsl(var(--foreground))",
        primary: {
          DEFAULT: "hsl(var(--primary))",
          foreground: "hsl(var(--primary-foreground))",
        },
        secondary: {
          DEFAULT: "hsl(var(--secondary))",
          foreground: "hsl(var(--secondary-foreground))",
        },
        destructive: {
          DEFAULT: "hsl(var(--destructive))",
          foreground: "hsl(var(--destructive-foreground))",
        },
        muted: {
          DEFAULT: "hsl(var(--muted))",
          foreground: "hsl(var(--muted-foreground))",
        },
        accent: {
          DEFAULT: "hsl(var(--accent))",
          foreground: "hsl(var(--accent-foreground))",
        },
        popover: {
          DEFAULT: "hsl(var(--popover))",
          foreground: "hsl(var(--popover-foreground))",
        },
        card: {
          DEFAULT: "hsl(var(--card))",
          foreground: "hsl(var(--card-foreground))",
        },
      },
      borderRadius: {
        lg: "var(--radius)",
        md: "calc(var(--radius) - 2px)",
        sm: "calc(var(--radius) - 4px)",
      },
      keyframes: {
        "accordion-down": {
          from: { height: "0" },
          to: { height: "var(--radix-accordion-content-height)" },
        },
        "accordion-up": {
          from: { height: "var(--radix-accordion-content-height)" },
          to: { height: "0" },
        },
      },
      animation: {
        "accordion-down": "accordion-down 0.2s ease-out",
        "accordion-up": "accordion-up 0.2s ease-out",
      },
    },
  },
  plugins: [require("tailwindcss-animate")],
}
EOF

# Add Tailwind directives and CSS variables to index.css
echo "🎨 Adding Tailwind directives and CSS variables..."
cat > src/index.css << 'EOF'
@tailwind base;
@tailwind components;
@tailwind utilities;

@layer base {
  :root {
    --background: 0 0% 100%;
    --foreground: 0 0% 3.9%;
    --card: 0 0% 100%;
    --card-foreground: 0 0% 3.9%;
    --popover: 0 0% 100%;
    --popover-foreground: 0 0% 3.9%;
    --primary: 0 0% 9%;
    --primary-foreground: 0 0% 98%;
    --secondary: 0 0% 96.1%;
    --secondary-foreground: 0 0% 9%;
    --muted: 0 0% 96.1%;
    --muted-foreground: 0 0% 45.1%;
    --accent: 0 0% 96.1%;
    --accent-foreground: 0 0% 9%;
    --destructive: 0 84.2% 60.2%;
    --destructive-foreground: 0 0% 98%;
    --border: 0 0% 89.8%;
    --input: 0 0% 89.8%;
    --ring: 0 0% 3.9%;
    --radius: 0.5rem;
  }

  .dark {
    --background: 0 0% 3.9%;
    --foreground: 0 0% 98%;
    --card: 0 0% 3.9%;
    --card-foreground: 0 0% 98%;
    --popover: 0 0% 3.9%;
    --popover-foreground: 0 0% 98%;
    --primary: 0 0% 98%;
    --primary-foreground: 0 0% 9%;
    --secondary: 0 0% 14.9%;
    --secondary-foreground: 0 0% 98%;
    --muted: 0 0% 14.9%;
    --muted-foreground: 0 0% 63.9%;
    --accent: 0 0% 14.9%;
    --accent-foreground: 0 0% 98%;
    --destructive: 0 62.8% 30.6%;
    --destructive-foreground: 0 0% 98%;
    --border: 0 0% 14.9%;
    --input: 0 0% 14.9%;
    --ring: 0 0% 83.1%;
  }
}

@layer base {
  * {
    @apply border-border;
  }
  body {
    @apply bg-background text-foreground;
  }
}
EOF

# Add path aliases to tsconfig.json
echo "🔧 Adding path aliases to tsconfig.json..."
node -e "
const fs = require('fs');
const config = JSON.parse(fs.readFileSync('tsconfig.json', 'utf8'));
config.compilerOptions = config.compilerOptions || {};
config.compilerOptions.baseUrl = '.';
config.compilerOptions.paths = { '@/*': ['./src/*'] };
fs.writeFileSync('tsconfig.json', JSON.stringify(config, null, 2));
"

# Add path aliases to tsconfig.app.json
echo "🔧 Adding path aliases to tsconfig.app.json..."
node -e "
const fs = require('fs');
const path = 'tsconfig.app.json';
const content = fs.readFileSync(path, 'utf8');
// Remove comments manually
const lines = content.split('\n').filter(line => !line.trim().startsWith('//'));
const jsonContent = lines.join('\n');
const config = JSON.parse(jsonContent.replace(/\/\*[\s\S]*?\*\//g, '').replace(/,(\s*[}\]])/g, '\$1'));
config.compilerOptions = config.compilerOptions || {};
config.compilerOptions.baseUrl = '.';
config.compilerOptions.paths = { '@/*': ['./src/*'] };
fs.writeFileSync(path, JSON.stringify(config, null, 2));
"

# Update vite.config.ts
echo "⚙️  Updating Vite configuration..."
cat > vite.config.ts << 'EOF'
import path from "path";
import react from "@vitejs/plugin-react";
import { defineConfig } from "vite";

export default defineConfig({
  plugins: [react()],
  resolve: {
    alias: {
      "@": path.resolve(__dirname, "./src"),
    },
  },
});
EOF

# Install all shadcn/ui dependencies
echo "📦 Installing shadcn/ui dependencies..."
pnpm install @radix-ui/react-accordion @radix-ui/react-aspect-ratio @radix-ui/react-avatar @radix-ui/react-checkbox @radix-ui/react-collapsible @radix-ui/react-context-menu @radix-ui/react-dialog @radix-ui/react-dropdown-menu @radix-ui/react-hover-card @radix-ui/react-label @radix-ui/react-menubar @radix-ui/react-navigation-menu @radix-ui/react-popover @radix-ui/react-progress @radix-ui/react-radio-group @radix-ui/react-scroll-area @radix-ui/react-select @radix-ui/react-separator @radix-ui/react-slider @radix-ui/react-slot @radix-ui/react-switch @radix-ui/react-tabs @radix-ui/react-toast @radix-ui/react-toggle @radix-ui/react-toggle-group @radix-ui/react-tooltip
pnpm install sonner cmdk vaul embla-carousel-react react-day-picker react-resizable-panels date-fns react-hook-form @hookform/resolvers zod

# Extract shadcn components from tarball
echo "📦 Extracting shadcn/ui components..."
tar -xzf "$COMPONENTS_TARBALL" -C src/

# Create components.json for reference
echo "📝 Creating components.json config..."
cat > components.json << 'EOF'
{
  "$schema": "https://ui.shadcn.com/schema.json",
  "style": "default",
  "rsc": false,
  "tsx": true,
  "tailwind": {
    "config": "tailwind.config.js",
    "css": "src/index.css",
    "baseColor": "slate",
    "cssVariables": true,
    "prefix": ""
  },
  "aliases": {
    "components": "@/components",
    "utils": "@/lib/utils",
    "ui": "@/components/ui",
    "lib": "@/lib",
    "hooks": "@/hooks"
  }
}
EOF

echo "✅ Setup complete! You can now use Tailwind CSS and shadcn/ui in your project."
echo ""
echo "📦 Included components (40+ total):"
echo "  - accordion, alert, aspect-ratio, avatar, badge, breadcrumb"
echo "  - button, calendar, card, carousel, checkbox, collapsible"
echo "  - command, context-menu, dialog, drawer, dropdown-menu"
echo "  - form, hover-card, input, label, menubar, navigation-menu"
echo "  - popover, progress, radio-group, resizable, scroll-area"
echo "  - select, separator, sheet, skeleton, slider, sonner"
echo "  - switch, table, tabs, textarea, toast, toggle, toggle-group, tooltip"
echo ""
echo "To start developing:"
echo "  cd $PROJECT_NAME"
echo "  pnpm dev"
echo ""
echo "📚 Import components like:"
echo "  import { Button } from '@/components/ui/button'"
echo "  import { Card, CardHeader, CardTitle, CardContent } from '@/components/ui/card'"
echo "  import { Dialog, DialogContent, DialogTrigger } from '@/components/ui/dialog'"

FILE:scripts/shadcn-components.tar.gz
[Binary or non-UTF8 file skipped during import]
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/web-artifacts-builder
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: theme-factory
description: Toolkit for styling artifacts with a theme. These artifacts can be slides, docs, reportings, HTML landing pages, etc. There are 10 pre-set themes with colors/fonts that you can apply to any artifact that has been creating, or can generate a new theme on-the-fly.
license: Complete terms in LICENSE.txt
---


# Theme Factory Skill

This skill provides a curated collection of professional font and color themes themes, each with carefully selected color palettes and font pairings. Once a theme is chosen, it can be applied to any artifact.

## Purpose

To apply consistent, professional styling to presentation slide decks, use this skill. Each theme includes:
- A cohesive color palette with hex codes
- Complementary font pairings for headers and body text
- A distinct visual identity suitable for different contexts and audiences

## Usage Instructions

To apply styling to a slide deck or other artifact:

1. **Show the theme showcase**: Display the `theme-showcase.pdf` file to allow users to see all available themes visually. Do not make any modifications to it; simply show the file for viewing.
2. **Ask for their choice**: Ask which theme to apply to the deck
3. **Wait for selection**: Get explicit confirmation about the chosen theme
4. **Apply the theme**: Once a theme has been chosen, apply the selected theme's colors and fonts to the deck/artifact

## Themes Available

The following 10 themes are available, each showcased in `theme-showcase.pdf`:

1. **Ocean Depths** - Professional and calming maritime theme
2. **Sunset Boulevard** - Warm and vibrant sunset colors
3. **Forest Canopy** - Natural and grounded earth tones
4. **Modern Minimalist** - Clean and contemporary grayscale
5. **Golden Hour** - Rich and warm autumnal palette
6. **Arctic Frost** - Cool and crisp winter-inspired theme
7. **Desert Rose** - Soft and sophisticated dusty tones
8. **Tech Innovation** - Bold and modern tech aesthetic
9. **Botanical Garden** - Fresh and organic garden colors
10. **Midnight Galaxy** - Dramatic and cosmic deep tones

## Theme Details

Each theme is defined in the `themes/` directory with complete specifications including:
- Cohesive color palette with hex codes
- Complementary font pairings for headers and body text
- Distinct visual identity suitable for different contexts and audiences

## Application Process

After a preferred theme is selected:
1. Read the corresponding theme file from the `themes/` directory
2. Apply the specified colors and fonts consistently throughout the deck
3. Ensure proper contrast and readability
4. Maintain the theme's visual identity across all slides

## Create your Own Theme
To handle cases where none of the existing themes work for an artifact, create a custom theme. Based on provided inputs, generate a new theme similar to the ones above. Give the theme a similar name describing what the font/color combinations represent. Use any basic description provided to choose appropriate colors/fonts. After generating the theme, show it for review and verification. Following that, apply the theme as described above.

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:theme-showcase.pdf
[Binary or non-UTF8 file skipped during import]
FILE:themes/arctic-frost.md
# Arctic Frost

A cool and crisp winter-inspired theme that conveys clarity, precision, and professionalism.

## Color Palette

- **Ice Blue**: `#d4e4f7` - Light backgrounds and highlights
- **Steel Blue**: `#4a6fa5` - Primary accent color
- **Silver**: `#c0c0c0` - Metallic accent elements
- **Crisp White**: `#fafafa` - Clean backgrounds and text

## Typography

- **Headers**: DejaVu Sans Bold
- **Body Text**: DejaVu Sans

## Best Used For

Healthcare presentations, technology solutions, winter sports, clean tech, pharmaceutical content.

FILE:themes/botanical-garden.md
# Botanical Garden

A fresh and organic theme featuring vibrant garden-inspired colors for lively presentations.

## Color Palette

- **Fern Green**: `#4a7c59` - Rich natural green
- **Marigold**: `#f9a620` - Bright floral accent
- **Terracotta**: `#b7472a` - Earthy warm tone
- **Cream**: `#f5f3ed` - Soft neutral backgrounds

## Typography

- **Headers**: DejaVu Serif Bold
- **Body Text**: DejaVu Sans

## Best Used For

Garden centers, food presentations, farm-to-table content, botanical brands, natural products.

FILE:themes/desert-rose.md
# Desert Rose

A soft and sophisticated theme with dusty, muted tones perfect for elegant presentations.

## Color Palette

- **Dusty Rose**: `#d4a5a5` - Soft primary color
- **Clay**: `#b87d6d` - Earthy accent
- **Sand**: `#e8d5c4` - Warm neutral backgrounds
- **Deep Burgundy**: `#5d2e46` - Rich dark contrast

## Typography

- **Headers**: FreeSans Bold
- **Body Text**: FreeSans

## Best Used For

Fashion presentations, beauty brands, wedding planning, interior design, boutique businesses.

FILE:themes/forest-canopy.md
# Forest Canopy

A natural and grounded theme featuring earth tones inspired by dense forest environments.

## Color Palette

- **Forest Green**: `#2d4a2b` - Primary dark green
- **Sage**: `#7d8471` - Muted green accent
- **Olive**: `#a4ac86` - Light accent color
- **Ivory**: `#faf9f6` - Backgrounds and text

## Typography

- **Headers**: FreeSerif Bold
- **Body Text**: FreeSans

## Best Used For

Environmental presentations, sustainability reports, outdoor brands, wellness content, organic products.

FILE:themes/golden-hour.md
# Golden Hour

A rich and warm autumnal palette that creates an inviting and sophisticated atmosphere.

## Color Palette

- **Mustard Yellow**: `#f4a900` - Bold primary accent
- **Terracotta**: `#c1666b` - Warm secondary color
- **Warm Beige**: `#d4b896` - Neutral backgrounds
- **Chocolate Brown**: `#4a403a` - Dark text and anchors

## Typography

- **Headers**: FreeSans Bold
- **Body Text**: FreeSans

## Best Used For

Restaurant presentations, hospitality brands, fall campaigns, cozy lifestyle content, artisan products.

FILE:themes/midnight-galaxy.md
# Midnight Galaxy

A dramatic and cosmic theme with deep purples and mystical tones for impactful presentations.

## Color Palette

- **Deep Purple**: `#2b1e3e` - Rich dark base
- **Cosmic Blue**: `#4a4e8f` - Mystical mid-tone
- **Lavender**: `#a490c2` - Soft accent color
- **Silver**: `#e6e6fa` - Light highlights and text

## Typography

- **Headers**: FreeSans Bold
- **Body Text**: FreeSans

## Best Used For

Entertainment industry, gaming presentations, nightlife venues, luxury brands, creative agencies.

FILE:themes/modern-minimalist.md
# Modern Minimalist

A clean and contemporary theme with a sophisticated grayscale palette for maximum versatility.

## Color Palette

- **Charcoal**: `#36454f` - Primary dark color
- **Slate Gray**: `#708090` - Medium gray for accents
- **Light Gray**: `#d3d3d3` - Backgrounds and dividers
- **White**: `#ffffff` - Text and clean backgrounds

## Typography

- **Headers**: DejaVu Sans Bold
- **Body Text**: DejaVu Sans

## Best Used For

Tech presentations, architecture portfolios, design showcases, modern business proposals, data visualization.

FILE:themes/ocean-depths.md
# Ocean Depths

A professional and calming maritime theme that evokes the serenity of deep ocean waters.

## Color Palette

- **Deep Navy**: `#1a2332` - Primary background color
- **Teal**: `#2d8b8b` - Accent color for highlights and emphasis
- **Seafoam**: `#a8dadc` - Secondary accent for lighter elements
- **Cream**: `#f1faee` - Text and light backgrounds

## Typography

- **Headers**: DejaVu Sans Bold
- **Body Text**: DejaVu Sans

## Best Used For

Corporate presentations, financial reports, professional consulting decks, trust-building content.

FILE:themes/sunset-boulevard.md
# Sunset Boulevard

A warm and vibrant theme inspired by golden hour sunsets, perfect for energetic and creative presentations.

## Color Palette

- **Burnt Orange**: `#e76f51` - Primary accent color
- **Coral**: `#f4a261` - Secondary warm accent
- **Warm Sand**: `#e9c46a` - Highlighting and backgrounds
- **Deep Purple**: `#264653` - Dark contrast and text

## Typography

- **Headers**: DejaVu Serif Bold
- **Body Text**: DejaVu Sans

## Best Used For

Creative pitches, marketing presentations, lifestyle brands, event promotions, inspirational content.

FILE:themes/tech-innovation.md
# Tech Innovation

A bold and modern theme with high-contrast colors perfect for cutting-edge technology presentations.

## Color Palette

- **Electric Blue**: `#0066ff` - Vibrant primary accent
- **Neon Cyan**: `#00ffff` - Bright highlight color
- **Dark Gray**: `#1e1e1e` - Deep backgrounds
- **White**: `#ffffff` - Clean text and contrast

## Typography

- **Headers**: DejaVu Sans Bold
- **Body Text**: DejaVu Sans

## Best Used For

Tech startups, software launches, innovation showcases, AI/ML presentations, digital transformation content.

FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/theme-factory
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: slack-gif-creator
description: Knowledge and utilities for creating animated GIFs optimized for Slack. Provides constraints, validation tools, and animation concepts. Use when users request animated GIFs for Slack like "make me a GIF of X doing Y for Slack."
license: Complete terms in LICENSE.txt
---

# Slack GIF Creator

A toolkit providing utilities and knowledge for creating animated GIFs optimized for Slack.

## Slack Requirements

**Dimensions:**
- Emoji GIFs: 128x128 (recommended)
- Message GIFs: 480x480

**Parameters:**
- FPS: 10-30 (lower is smaller file size)
- Colors: 48-128 (fewer = smaller file size)
- Duration: Keep under 3 seconds for emoji GIFs

## Core Workflow

```python
from core.gif_builder import GIFBuilder
from PIL import Image, ImageDraw

# 1. Create builder
builder = GIFBuilder(width=128, height=128, fps=10)

# 2. Generate frames
for i in range(12):
    frame = Image.new('RGB', (128, 128), (240, 248, 255))
    draw = ImageDraw.Draw(frame)

    # Draw your animation using PIL primitives
    # (circles, polygons, lines, etc.)

    builder.add_frame(frame)

# 3. Save with optimization
builder.save('output.gif', num_colors=48, optimize_for_emoji=True)
```

## Drawing Graphics

### Working with User-Uploaded Images
If a user uploads an image, consider whether they want to:
- **Use it directly** (e.g., "animate this", "split this into frames")
- **Use it as inspiration** (e.g., "make something like this")

Load and work with images using PIL:
```python
from PIL import Image

uploaded = Image.open('file.png')
# Use directly, or just as reference for colors/style
```

### Drawing from Scratch
When drawing graphics from scratch, use PIL ImageDraw primitives:

```python
from PIL import ImageDraw

draw = ImageDraw.Draw(frame)

# Circles/ovals
draw.ellipse([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)

# Stars, triangles, any polygon
points = [(x1, y1), (x2, y2), (x3, y3), ...]
draw.polygon(points, fill=(r, g, b), outline=(r, g, b), width=3)

# Lines
draw.line([(x1, y1), (x2, y2)], fill=(r, g, b), width=5)

# Rectangles
draw.rectangle([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)
```

**Don't use:** Emoji fonts (unreliable across platforms) or assume pre-packaged graphics exist in this skill.

### Making Graphics Look Good

Graphics should look polished and creative, not basic. Here's how:

**Use thicker lines** - Always set `width=2` or higher for outlines and lines. Thin lines (width=1) look choppy and amateurish.

**Add visual depth**:
- Use gradients for backgrounds (`create_gradient_background`)
- Layer multiple shapes for complexity (e.g., a star with a smaller star inside)

**Make shapes more interesting**:
- Don't just draw a plain circle - add highlights, rings, or patterns
- Stars can have glows (draw larger, semi-transparent versions behind)
- Combine multiple shapes (stars + sparkles, circles + rings)

**Pay attention to colors**:
- Use vibrant, complementary colors
- Add contrast (dark outlines on light shapes, light outlines on dark shapes)
- Consider the overall composition

**For complex shapes** (hearts, snowflakes, etc.):
- Use combinations of polygons and ellipses
- Calculate points carefully for symmetry
- Add details (a heart can have a highlight curve, snowflakes have intricate branches)

Be creative and detailed! A good Slack GIF should look polished, not like placeholder graphics.

## Available Utilities

### GIFBuilder (`core.gif_builder`)
Assembles frames and optimizes for Slack:
```python
builder = GIFBuilder(width=128, height=128, fps=10)
builder.add_frame(frame)  # Add PIL Image
builder.add_frames(frames)  # Add list of frames
builder.save('out.gif', num_colors=48, optimize_for_emoji=True, remove_duplicates=True)
```

### Validators (`core.validators`)
Check if GIF meets Slack requirements:
```python
from core.validators import validate_gif, is_slack_ready

# Detailed validation
passes, info = validate_gif('my.gif', is_emoji=True, verbose=True)

# Quick check
if is_slack_ready('my.gif'):
    print("Ready!")
```

### Easing Functions (`core.easing`)
Smooth motion instead of linear:
```python
from core.easing import interpolate

# Progress from 0.0 to 1.0
t = i / (num_frames - 1)

# Apply easing
y = interpolate(start=0, end=400, t=t, easing='ease_out')

# Available: linear, ease_in, ease_out, ease_in_out,
#           bounce_out, elastic_out, back_out
```

### Frame Helpers (`core.frame_composer`)
Convenience functions for common needs:
```python
from core.frame_composer import (
    create_blank_frame,         # Solid color background
    create_gradient_background,  # Vertical gradient
    draw_circle,                # Helper for circles
    draw_text,                  # Simple text rendering
    draw_star                   # 5-pointed star
)
```

## Animation Concepts

### Shake/Vibrate
Offset object position with oscillation:
- Use `math.sin()` or `math.cos()` with frame index
- Add small random variations for natural feel
- Apply to x and/or y position

### Pulse/Heartbeat
Scale object size rhythmically:
- Use `math.sin(t * frequency * 2 * math.pi)` for smooth pulse
- For heartbeat: two quick pulses then pause (adjust sine wave)
- Scale between 0.8 and 1.2 of base size

### Bounce
Object falls and bounces:
- Use `interpolate()` with `easing='bounce_out'` for landing
- Use `easing='ease_in'` for falling (accelerating)
- Apply gravity by increasing y velocity each frame

### Spin/Rotate
Rotate object around center:
- PIL: `image.rotate(angle, resample=Image.BICUBIC)`
- For wobble: use sine wave for angle instead of linear

### Fade In/Out
Gradually appear or disappear:
- Create RGBA image, adjust alpha channel
- Or use `Image.blend(image1, image2, alpha)`
- Fade in: alpha from 0 to 1
- Fade out: alpha from 1 to 0

### Slide
Move object from off-screen to position:
- Start position: outside frame bounds
- End position: target location
- Use `interpolate()` with `easing='ease_out'` for smooth stop
- For overshoot: use `easing='back_out'`

### Zoom
Scale and position for zoom effect:
- Zoom in: scale from 0.1 to 2.0, crop center
- Zoom out: scale from 2.0 to 1.0
- Can add motion blur for drama (PIL filter)

### Explode/Particle Burst
Create particles radiating outward:
- Generate particles with random angles and velocities
- Update each particle: `x += vx`, `y += vy`
- Add gravity: `vy += gravity_constant`
- Fade out particles over time (reduce alpha)

## Optimization Strategies

Only when asked to make the file size smaller, implement a few of the following methods:

1. **Fewer frames** - Lower FPS (10 instead of 20) or shorter duration
2. **Fewer colors** - `num_colors=48` instead of 128
3. **Smaller dimensions** - 128x128 instead of 480x480
4. **Remove duplicates** - `remove_duplicates=True` in save()
5. **Emoji mode** - `optimize_for_emoji=True` auto-optimizes

```python
# Maximum optimization for emoji
builder.save(
    'emoji.gif',
    num_colors=48,
    optimize_for_emoji=True,
    remove_duplicates=True
)
```

## Philosophy

This skill provides:
- **Knowledge**: Slack's requirements and animation concepts
- **Utilities**: GIFBuilder, validators, easing functions
- **Flexibility**: Create the animation logic using PIL primitives

It does NOT provide:
- Rigid animation templates or pre-made functions
- Emoji font rendering (unreliable across platforms)
- A library of pre-packaged graphics built into the skill

**Note on user uploads**: This skill doesn't include pre-built graphics, but if a user uploads an image, use PIL to load and work with it - interpret based on their request whether they want it used directly or just as inspiration.

Be creative! Combine concepts (bouncing + rotating, pulsing + sliding, etc.) and use PIL's full capabilities.

## Dependencies

```bash
pip install pillow imageio numpy
```

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:core/easing.py
#!/usr/bin/env python3
"""
Easing Functions - Timing functions for smooth animations.

Provides various easing functions for natural motion and timing.
All functions take a value t (0.0 to 1.0) and return eased value (0.0 to 1.0).
"""

import math


def linear(t: float) -> float:
    """Linear interpolation (no easing)."""
    return t


def ease_in_quad(t: float) -> float:
    """Quadratic ease-in (slow start, accelerating)."""
    return t * t


def ease_out_quad(t: float) -> float:
    """Quadratic ease-out (fast start, decelerating)."""
    return t * (2 - t)


def ease_in_out_quad(t: float) -> float:
    """Quadratic ease-in-out (slow start and end)."""
    if t < 0.5:
        return 2 * t * t
    return -1 + (4 - 2 * t) * t


def ease_in_cubic(t: float) -> float:
    """Cubic ease-in (slow start)."""
    return t * t * t


def ease_out_cubic(t: float) -> float:
    """Cubic ease-out (fast start)."""
    return (t - 1) * (t - 1) * (t - 1) + 1


def ease_in_out_cubic(t: float) -> float:
    """Cubic ease-in-out."""
    if t < 0.5:
        return 4 * t * t * t
    return (t - 1) * (2 * t - 2) * (2 * t - 2) + 1


def ease_in_bounce(t: float) -> float:
    """Bounce ease-in (bouncy start)."""
    return 1 - ease_out_bounce(1 - t)


def ease_out_bounce(t: float) -> float:
    """Bounce ease-out (bouncy end)."""
    if t < 1 / 2.75:
        return 7.5625 * t * t
    elif t < 2 / 2.75:
        t -= 1.5 / 2.75
        return 7.5625 * t * t + 0.75
    elif t < 2.5 / 2.75:
        t -= 2.25 / 2.75
        return 7.5625 * t * t + 0.9375
    else:
        t -= 2.625 / 2.75
        return 7.5625 * t * t + 0.984375


def ease_in_out_bounce(t: float) -> float:
    """Bounce ease-in-out."""
    if t < 0.5:
        return ease_in_bounce(t * 2) * 0.5
    return ease_out_bounce(t * 2 - 1) * 0.5 + 0.5


def ease_in_elastic(t: float) -> float:
    """Elastic ease-in (spring effect)."""
    if t == 0 or t == 1:
        return t
    return -math.pow(2, 10 * (t - 1)) * math.sin((t - 1.1) * 5 * math.pi)


def ease_out_elastic(t: float) -> float:
    """Elastic ease-out (spring effect)."""
    if t == 0 or t == 1:
        return t
    return math.pow(2, -10 * t) * math.sin((t - 0.1) * 5 * math.pi) + 1


def ease_in_out_elastic(t: float) -> float:
    """Elastic ease-in-out."""
    if t == 0 or t == 1:
        return t
    t = t * 2 - 1
    if t < 0:
        return -0.5 * math.pow(2, 10 * t) * math.sin((t - 0.1) * 5 * math.pi)
    return math.pow(2, -10 * t) * math.sin((t - 0.1) * 5 * math.pi) * 0.5 + 1


# Convenience mapping
EASING_FUNCTIONS = {
    "linear": linear,
    "ease_in": ease_in_quad,
    "ease_out": ease_out_quad,
    "ease_in_out": ease_in_out_quad,
    "bounce_in": ease_in_bounce,
    "bounce_out": ease_out_bounce,
    "bounce": ease_in_out_bounce,
    "elastic_in": ease_in_elastic,
    "elastic_out": ease_out_elastic,
    "elastic": ease_in_out_elastic,
}


def get_easing(name: str = "linear"):
    """Get easing function by name."""
    return EASING_FUNCTIONS.get(name, linear)


def interpolate(start: float, end: float, t: float, easing: str = "linear") -> float:
    """
    Interpolate between two values with easing.

    Args:
        start: Start value
        end: End value
        t: Progress from 0.0 to 1.0
        easing: Name of easing function

    Returns:
        Interpolated value
    """
    ease_func = get_easing(easing)
    eased_t = ease_func(t)
    return start + (end - start) * eased_t


def ease_back_in(t: float) -> float:
    """Back ease-in (slight overshoot backward before forward motion)."""
    c1 = 1.70158
    c3 = c1 + 1
    return c3 * t * t * t - c1 * t * t


def ease_back_out(t: float) -> float:
    """Back ease-out (overshoot forward then settle back)."""
    c1 = 1.70158
    c3 = c1 + 1
    return 1 + c3 * pow(t - 1, 3) + c1 * pow(t - 1, 2)


def ease_back_in_out(t: float) -> float:
    """Back ease-in-out (overshoot at both ends)."""
    c1 = 1.70158
    c2 = c1 * 1.525
    if t < 0.5:
        return (pow(2 * t, 2) * ((c2 + 1) * 2 * t - c2)) / 2
    return (pow(2 * t - 2, 2) * ((c2 + 1) * (t * 2 - 2) + c2) + 2) / 2


def apply_squash_stretch(
    base_scale: tuple[float, float], intensity: float, direction: str = "vertical"
) -> tuple[float, float]:
    """
    Calculate squash and stretch scales for more dynamic animation.

    Args:
        base_scale: (width_scale, height_scale) base scales
        intensity: Squash/stretch intensity (0.0-1.0)
        direction: 'vertical', 'horizontal', or 'both'

    Returns:
        (width_scale, height_scale) with squash/stretch applied
    """
    width_scale, height_scale = base_scale

    if direction == "vertical":
        # Compress vertically, expand horizontally (preserve volume)
        height_scale *= 1 - intensity * 0.5
        width_scale *= 1 + intensity * 0.5
    elif direction == "horizontal":
        # Compress horizontally, expand vertically
        width_scale *= 1 - intensity * 0.5
        height_scale *= 1 + intensity * 0.5
    elif direction == "both":
        # General squash (both dimensions)
        width_scale *= 1 - intensity * 0.3
        height_scale *= 1 - intensity * 0.3

    return (width_scale, height_scale)


def calculate_arc_motion(
    start: tuple[float, float], end: tuple[float, float], height: float, t: float
) -> tuple[float, float]:
    """
    Calculate position along a parabolic arc (natural motion path).

    Args:
        start: (x, y) starting position
        end: (x, y) ending position
        height: Arc height at midpoint (positive = upward)
        t: Progress (0.0-1.0)

    Returns:
        (x, y) position along arc
    """
    x1, y1 = start
    x2, y2 = end

    # Linear interpolation for x
    x = x1 + (x2 - x1) * t

    # Parabolic interpolation for y
    # y = start + progress * (end - start) + arc_offset
    # Arc offset peaks at t=0.5
    arc_offset = 4 * height * t * (1 - t)
    y = y1 + (y2 - y1) * t - arc_offset

    return (x, y)


# Add new easing functions to the convenience mapping
EASING_FUNCTIONS.update(
    {
        "back_in": ease_back_in,
        "back_out": ease_back_out,
        "back_in_out": ease_back_in_out,
        "anticipate": ease_back_in,  # Alias
        "overshoot": ease_back_out,  # Alias
    }
)

FILE:core/frame_composer.py
#!/usr/bin/env python3
"""
Frame Composer - Utilities for composing visual elements into frames.

Provides functions for drawing shapes, text, emojis, and compositing elements
together to create animation frames.
"""

from typing import Optional

import numpy as np
from PIL import Image, ImageDraw, ImageFont


def create_blank_frame(
    width: int, height: int, color: tuple[int, int, int] = (255, 255, 255)
) -> Image.Image:
    """
    Create a blank frame with solid color background.

    Args:
        width: Frame width
        height: Frame height
        color: RGB color tuple (default: white)

    Returns:
        PIL Image
    """
    return Image.new("RGB", (width, height), color)


def draw_circle(
    frame: Image.Image,
    center: tuple[int, int],
    radius: int,
    fill_color: Optional[tuple[int, int, int]] = None,
    outline_color: Optional[tuple[int, int, int]] = None,
    outline_width: int = 1,
) -> Image.Image:
    """
    Draw a circle on a frame.

    Args:
        frame: PIL Image to draw on
        center: (x, y) center position
        radius: Circle radius
        fill_color: RGB fill color (None for no fill)
        outline_color: RGB outline color (None for no outline)
        outline_width: Outline width in pixels

    Returns:
        Modified frame
    """
    draw = ImageDraw.Draw(frame)
    x, y = center
    bbox = [x - radius, y - radius, x + radius, y + radius]
    draw.ellipse(bbox, fill=fill_color, outline=outline_color, width=outline_width)
    return frame


def draw_text(
    frame: Image.Image,
    text: str,
    position: tuple[int, int],
    color: tuple[int, int, int] = (0, 0, 0),
    centered: bool = False,
) -> Image.Image:
    """
    Draw text on a frame.

    Args:
        frame: PIL Image to draw on
        text: Text to draw
        position: (x, y) position (top-left unless centered=True)
        color: RGB text color
        centered: If True, center text at position

    Returns:
        Modified frame
    """
    draw = ImageDraw.Draw(frame)

    # Uses Pillow's default font.
    # If the font should be changed for the emoji, add additional logic here.
    font = ImageFont.load_default()

    if centered:
        bbox = draw.textbbox((0, 0), text, font=font)
        text_width = bbox[2] - bbox[0]
        text_height = bbox[3] - bbox[1]
        x = position[0] - text_width // 2
        y = position[1] - text_height // 2
        position = (x, y)

    draw.text(position, text, fill=color, font=font)
    return frame


def create_gradient_background(
    width: int,
    height: int,
    top_color: tuple[int, int, int],
    bottom_color: tuple[int, int, int],
) -> Image.Image:
    """
    Create a vertical gradient background.

    Args:
        width: Frame width
        height: Frame height
        top_color: RGB color at top
        bottom_color: RGB color at bottom

    Returns:
        PIL Image with gradient
    """
    frame = Image.new("RGB", (width, height))
    draw = ImageDraw.Draw(frame)

    # Calculate color step for each row
    r1, g1, b1 = top_color
    r2, g2, b2 = bottom_color

    for y in range(height):
        # Interpolate color
        ratio = y / height
        r = int(r1 * (1 - ratio) + r2 * ratio)
        g = int(g1 * (1 - ratio) + g2 * ratio)
        b = int(b1 * (1 - ratio) + b2 * ratio)

        # Draw horizontal line
        draw.line([(0, y), (width, y)], fill=(r, g, b))

    return frame


def draw_star(
    frame: Image.Image,
    center: tuple[int, int],
    size: int,
    fill_color: tuple[int, int, int],
    outline_color: Optional[tuple[int, int, int]] = None,
    outline_width: int = 1,
) -> Image.Image:
    """
    Draw a 5-pointed star.

    Args:
        frame: PIL Image to draw on
        center: (x, y) center position
        size: Star size (outer radius)
        fill_color: RGB fill color
        outline_color: RGB outline color (None for no outline)
        outline_width: Outline width

    Returns:
        Modified frame
    """
    import math

    draw = ImageDraw.Draw(frame)
    x, y = center

    # Calculate star points
    points = []
    for i in range(10):
        angle = (i * 36 - 90) * math.pi / 180  # 36 degrees per point, start at top
        radius = size if i % 2 == 0 else size * 0.4  # Alternate between outer and inner
        px = x + radius * math.cos(angle)
        py = y + radius * math.sin(angle)
        points.append((px, py))

    # Draw star
    draw.polygon(points, fill=fill_color, outline=outline_color, width=outline_width)

    return frame

FILE:core/gif_builder.py
#!/usr/bin/env python3
"""
GIF Builder - Core module for assembling frames into GIFs optimized for Slack.

This module provides the main interface for creating GIFs from programmatically
generated frames, with automatic optimization for Slack's requirements.
"""

from pathlib import Path
from typing import Optional

import imageio.v3 as imageio
import numpy as np
from PIL import Image


class GIFBuilder:
    """Builder for creating optimized GIFs from frames."""

    def __init__(self, width: int = 480, height: int = 480, fps: int = 15):
        """
        Initialize GIF builder.

        Args:
            width: Frame width in pixels
            height: Frame height in pixels
            fps: Frames per second
        """
        self.width = width
        self.height = height
        self.fps = fps
        self.frames: list[np.ndarray] = []

    def add_frame(self, frame: np.ndarray | Image.Image):
        """
        Add a frame to the GIF.

        Args:
            frame: Frame as numpy array or PIL Image (will be converted to RGB)
        """
        if isinstance(frame, Image.Image):
            frame = np.array(frame.convert("RGB"))

        # Ensure frame is correct size
        if frame.shape[:2] != (self.height, self.width):
            pil_frame = Image.fromarray(frame)
            pil_frame = pil_frame.resize(
                (self.width, self.height), Image.Resampling.LANCZOS
            )
            frame = np.array(pil_frame)

        self.frames.append(frame)

    def add_frames(self, frames: list[np.ndarray | Image.Image]):
        """Add multiple frames at once."""
        for frame in frames:
            self.add_frame(frame)

    def optimize_colors(
        self, num_colors: int = 128, use_global_palette: bool = True
    ) -> list[np.ndarray]:
        """
        Reduce colors in all frames using quantization.

        Args:
            num_colors: Target number of colors (8-256)
            use_global_palette: Use a single palette for all frames (better compression)

        Returns:
            List of color-optimized frames
        """
        optimized = []

        if use_global_palette and len(self.frames) > 1:
            # Create a global palette from all frames
            # Sample frames to build palette
            sample_size = min(5, len(self.frames))
            sample_indices = [
                int(i * len(self.frames) / sample_size) for i in range(sample_size)
            ]
            sample_frames = [self.frames[i] for i in sample_indices]

            # Combine sample frames into a single image for palette generation
            # Flatten each frame to get all pixels, then stack them
            all_pixels = np.vstack(
                [f.reshape(-1, 3) for f in sample_frames]
            )  # (total_pixels, 3)

            # Create a properly-shaped RGB image from the pixel data
            # We'll make a roughly square image from all the pixels
            total_pixels = len(all_pixels)
            width = min(512, int(np.sqrt(total_pixels)))  # Reasonable width, max 512
            height = (total_pixels + width - 1) // width  # Ceiling division

            # Pad if necessary to fill the rectangle
            pixels_needed = width * height
            if pixels_needed > total_pixels:
                padding = np.zeros((pixels_needed - total_pixels, 3), dtype=np.uint8)
                all_pixels = np.vstack([all_pixels, padding])

            # Reshape to proper RGB image format (H, W, 3)
            img_array = (
                all_pixels[:pixels_needed].reshape(height, width, 3).astype(np.uint8)
            )
            combined_img = Image.fromarray(img_array, mode="RGB")

            # Generate global palette
            global_palette = combined_img.quantize(colors=num_colors, method=2)

            # Apply global palette to all frames
            for frame in self.frames:
                pil_frame = Image.fromarray(frame)
                quantized = pil_frame.quantize(palette=global_palette, dither=1)
                optimized.append(np.array(quantized.convert("RGB")))
        else:
            # Use per-frame quantization
            for frame in self.frames:
                pil_frame = Image.fromarray(frame)
                quantized = pil_frame.quantize(colors=num_colors, method=2, dither=1)
                optimized.append(np.array(quantized.convert("RGB")))

        return optimized

    def deduplicate_frames(self, threshold: float = 0.9995) -> int:
        """
        Remove duplicate or near-duplicate consecutive frames.

        Args:
            threshold: Similarity threshold (0.0-1.0). Higher = more strict (0.9995 = nearly identical).
                      Use 0.9995+ to preserve subtle animations, 0.98 for aggressive removal.

        Returns:
            Number of frames removed
        """
        if len(self.frames) < 2:
            return 0

        deduplicated = [self.frames[0]]
        removed_count = 0

        for i in range(1, len(self.frames)):
            # Compare with previous frame
            prev_frame = np.array(deduplicated[-1], dtype=np.float32)
            curr_frame = np.array(self.frames[i], dtype=np.float32)

            # Calculate similarity (normalized)
            diff = np.abs(prev_frame - curr_frame)
            similarity = 1.0 - (np.mean(diff) / 255.0)

            # Keep frame if sufficiently different
            # High threshold (0.9995+) means only remove nearly identical frames
            if similarity < threshold:
                deduplicated.append(self.frames[i])
            else:
                removed_count += 1

        self.frames = deduplicated
        return removed_count

    def save(
        self,
        output_path: str | Path,
        num_colors: int = 128,
        optimize_for_emoji: bool = False,
        remove_duplicates: bool = False,
    ) -> dict:
        """
        Save frames as optimized GIF for Slack.

        Args:
            output_path: Where to save the GIF
            num_colors: Number of colors to use (fewer = smaller file)
            optimize_for_emoji: If True, optimize for emoji size (128x128, fewer colors)
            remove_duplicates: If True, remove duplicate consecutive frames (opt-in)

        Returns:
            Dictionary with file info (path, size, dimensions, frame_count)
        """
        if not self.frames:
            raise ValueError("No frames to save. Add frames with add_frame() first.")

        output_path = Path(output_path)

        # Remove duplicate frames to reduce file size
        if remove_duplicates:
            removed = self.deduplicate_frames(threshold=0.9995)
            if removed > 0:
                print(
                    f"  Removed {removed} nearly identical frames (preserved subtle animations)"
                )

        # Optimize for emoji if requested
        if optimize_for_emoji:
            if self.width > 128 or self.height > 128:
                print(
                    f"  Resizing from {self.width}x{self.height} to 128x128 for emoji"
                )
                self.width = 128
                self.height = 128
                # Resize all frames
                resized_frames = []
                for frame in self.frames:
                    pil_frame = Image.fromarray(frame)
                    pil_frame = pil_frame.resize((128, 128), Image.Resampling.LANCZOS)
                    resized_frames.append(np.array(pil_frame))
                self.frames = resized_frames
            num_colors = min(num_colors, 48)  # More aggressive color limit for emoji

            # More aggressive FPS reduction for emoji
            if len(self.frames) > 12:
                print(
                    f"  Reducing frames from {len(self.frames)} to ~12 for emoji size"
                )
                # Keep every nth frame to get close to 12 frames
                keep_every = max(1, len(self.frames) // 12)
                self.frames = [
                    self.frames[i] for i in range(0, len(self.frames), keep_every)
                ]

        # Optimize colors with global palette
        optimized_frames = self.optimize_colors(num_colors, use_global_palette=True)

        # Calculate frame duration in milliseconds
        frame_duration = 1000 / self.fps

        # Save GIF
        imageio.imwrite(
            output_path,
            optimized_frames,
            duration=frame_duration,
            loop=0,  # Infinite loop
        )

        # Get file info
        file_size_kb = output_path.stat().st_size / 1024
        file_size_mb = file_size_kb / 1024

        info = {
            "path": str(output_path),
            "size_kb": file_size_kb,
            "size_mb": file_size_mb,
            "dimensions": f"{self.width}x{self.height}",
            "frame_count": len(optimized_frames),
            "fps": self.fps,
            "duration_seconds": len(optimized_frames) / self.fps,
            "colors": num_colors,
        }

        # Print info
        print(f"\n✓ GIF created successfully!")
        print(f"  Path: {output_path}")
        print(f"  Size: {file_size_kb:.1f} KB ({file_size_mb:.2f} MB)")
        print(f"  Dimensions: {self.width}x{self.height}")
        print(f"  Frames: {len(optimized_frames)} @ {self.fps} fps")
        print(f"  Duration: {info['duration_seconds']:.1f}s")
        print(f"  Colors: {num_colors}")

        # Size info
        if optimize_for_emoji:
            print(f"  Optimized for emoji (128x128, reduced colors)")
        if file_size_mb > 1.0:
            print(f"\n  Note: Large file size ({file_size_kb:.1f} KB)")
            print("  Consider: fewer frames, smaller dimensions, or fewer colors")

        return info

    def clear(self):
        """Clear all frames (useful for creating multiple GIFs)."""
        self.frames = []

FILE:core/validators.py
#!/usr/bin/env python3
"""
Validators - Check if GIFs meet Slack's requirements.

These validators help ensure your GIFs meet Slack's size and dimension constraints.
"""

from pathlib import Path


def validate_gif(
    gif_path: str | Path, is_emoji: bool = True, verbose: bool = True
) -> tuple[bool, dict]:
    """
    Validate GIF for Slack (dimensions, size, frame count).

    Args:
        gif_path: Path to GIF file
        is_emoji: True for emoji (128x128 recommended), False for message GIF
        verbose: Print validation details

    Returns:
        Tuple of (passes: bool, results: dict with all details)
    """
    from PIL import Image

    gif_path = Path(gif_path)

    if not gif_path.exists():
        return False, {"error": f"File not found: {gif_path}"}

    # Get file size
    size_bytes = gif_path.stat().st_size
    size_kb = size_bytes / 1024
    size_mb = size_kb / 1024

    # Get dimensions and frame info
    try:
        with Image.open(gif_path) as img:
            width, height = img.size

            # Count frames
            frame_count = 0
            try:
                while True:
                    img.seek(frame_count)
                    frame_count += 1
            except EOFError:
                pass

            # Get duration
            try:
                duration_ms = img.info.get("duration", 100)
                total_duration = (duration_ms * frame_count) / 1000
                fps = frame_count / total_duration if total_duration > 0 else 0
            except:
                total_duration = None
                fps = None

    except Exception as e:
        return False, {"error": f"Failed to read GIF: {e}"}

    # Validate dimensions
    if is_emoji:
        optimal = width == height == 128
        acceptable = width == height and 64 <= width <= 128
        dim_pass = acceptable
    else:
        aspect_ratio = (
            max(width, height) / min(width, height)
            if min(width, height) > 0
            else float("inf")
        )
        dim_pass = aspect_ratio <= 2.0 and 320 <= min(width, height) <= 640

    results = {
        "file": str(gif_path),
        "passes": dim_pass,
        "width": width,
        "height": height,
        "size_kb": size_kb,
        "size_mb": size_mb,
        "frame_count": frame_count,
        "duration_seconds": total_duration,
        "fps": fps,
        "is_emoji": is_emoji,
        "optimal": optimal if is_emoji else None,
    }

    # Print if verbose
    if verbose:
        print(f"\nValidating {gif_path.name}:")
        print(
            f"  Dimensions: {width}x{height}"
            + (
                f" ({'optimal' if optimal else 'acceptable'})"
                if is_emoji and acceptable
                else ""
            )
        )
        print(
            f"  Size: {size_kb:.1f} KB"
            + (f" ({size_mb:.2f} MB)" if size_mb >= 1.0 else "")
        )
        print(
            f"  Frames: {frame_count}"
            + (f" @ {fps:.1f} fps ({total_duration:.1f}s)" if fps else "")
        )

        if not dim_pass:
            print(
                f"  Note: {'Emoji should be 128x128' if is_emoji else 'Unusual dimensions for Slack'}"
            )

        if size_mb > 5.0:
            print(f"  Note: Large file size - consider fewer frames/colors")

    return dim_pass, results


def is_slack_ready(
    gif_path: str | Path, is_emoji: bool = True, verbose: bool = True
) -> bool:
    """
    Quick check if GIF is ready for Slack.

    Args:
        gif_path: Path to GIF file
        is_emoji: True for emoji GIF, False for message GIF
        verbose: Print feedback

    Returns:
        True if dimensions are acceptable
    """
    passes, _ = validate_gif(gif_path, is_emoji, verbose)
    return passes

FILE:requirements.txt
pillow>=10.0.0
imageio>=2.31.0
imageio-ffmpeg>=0.4.9
numpy>=1.24.0
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/slack-gif-creator
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: skill-creator
description: Create new skills, modify and improve existing skills, and measure skill performance. Use when users want to create a skill from scratch, edit, or optimize an existing skill, run evals to test a skill, benchmark skill performance with variance analysis, or optimize a skill's description for better triggering accuracy.
---

# Skill Creator

A skill for creating new skills and iteratively improving them.

At a high level, the process of creating a skill goes like this:

- Decide what you want the skill to do and roughly how it should do it
- Write a draft of the skill
- Create a few test prompts and run claude-with-access-to-the-skill on them
- Help the user evaluate the results both qualitatively and quantitatively
  - While the runs happen in the background, draft some quantitative evals if there aren't any (if there are some, you can either use as is or modify if you feel something needs to change about them). Then explain them to the user (or if they already existed, explain the ones that already exist)
  - Use the `eval-viewer/generate_review.py` script to show the user the results for them to look at, and also let them look at the quantitative metrics
- Rewrite the skill based on feedback from the user's evaluation of the results (and also if there are any glaring flaws that become apparent from the quantitative benchmarks)
- Repeat until you're satisfied
- Expand the test set and try again at larger scale

Your job when using this skill is to figure out where the user is in this process and then jump in and help them progress through these stages. So for instance, maybe they're like "I want to make a skill for X". You can help narrow down what they mean, write a draft, write the test cases, figure out how they want to evaluate, run all the prompts, and repeat.

On the other hand, maybe they already have a draft of the skill. In this case you can go straight to the eval/iterate part of the loop.

Of course, you should always be flexible and if the user is like "I don't need to run a bunch of evaluations, just vibe with me", you can do that instead.

Then after the skill is done (but again, the order is flexible), you can also run the skill description improver, which we have a whole separate script for, to optimize the triggering of the skill.

Cool? Cool.

## Communicating with the user

The skill creator is liable to be used by people across a wide range of familiarity with coding jargon. If you haven't heard (and how could you, it's only very recently that it started), there's a trend now where the power of Claude is inspiring plumbers to open up their terminals, parents and grandparents to google "how to install npm". On the other hand, the bulk of users are probably fairly computer-literate.

So please pay attention to context cues to understand how to phrase your communication! In the default case, just to give you some idea:

- "evaluation" and "benchmark" are borderline, but OK
- for "JSON" and "assertion" you want to see serious cues from the user that they know what those things are before using them without explaining them

It's OK to briefly explain terms if you're in doubt, and feel free to clarify terms with a short definition if you're unsure if the user will get it.

---

## Creating a skill

### Capture Intent

Start by understanding the user's intent. The current conversation might already contain a workflow the user wants to capture (e.g., they say "turn this into a skill"). If so, extract answers from the conversation history first — the tools used, the sequence of steps, corrections the user made, input/output formats observed. The user may need to fill the gaps, and should confirm before proceeding to the next step.

1. What should this skill enable Claude to do?
2. When should this skill trigger? (what user phrases/contexts)
3. What's the expected output format?
4. Should we set up test cases to verify the skill works? Skills with objectively verifiable outputs (file transforms, data extraction, code generation, fixed workflow steps) benefit from test cases. Skills with subjective outputs (writing style, art) often don't need them. Suggest the appropriate default based on the skill type, but let the user decide.

### Interview and Research

Proactively ask questions about edge cases, input/output formats, example files, success criteria, and dependencies. Wait to write test prompts until you've got this part ironed out.

Check available MCPs - if useful for research (searching docs, finding similar skills, looking up best practices), research in parallel via subagents if available, otherwise inline. Come prepared with context to reduce burden on the user.

### Write the SKILL.md

Based on the user interview, fill in these components:

- **name**: Skill identifier
- **description**: When to trigger, what it does. This is the primary triggering mechanism - include both what the skill does AND specific contexts for when to use it. All "when to use" info goes here, not in the body. Note: currently Claude has a tendency to "undertrigger" skills -- to not use them when they'd be useful. To combat this, please make the skill descriptions a little bit "pushy". So for instance, instead of "How to build a simple fast dashboard to display internal Anthropic data.", you might write "How to build a simple fast dashboard to display internal Anthropic data. Make sure to use this skill whenever the user mentions dashboards, data visualization, internal metrics, or wants to display any kind of company data, even if they don't explicitly ask for a 'dashboard.'"
- **compatibility**: Required tools, dependencies (optional, rarely needed)
- **the rest of the skill :)**

### Skill Writing Guide

#### Anatomy of a Skill

```
skill-name/
├── SKILL.md (required)
│   ├── YAML frontmatter (name, description required)
│   └── Markdown instructions
└── Bundled Resources (optional)
    ├── scripts/    - Executable code for deterministic/repetitive tasks
    ├── references/ - Docs loaded into context as needed
    └── assets/     - Files used in output (templates, icons, fonts)
```

#### Progressive Disclosure

Skills use a three-level loading system:
1. **Metadata** (name + description) - Always in context (~100 words)
2. **SKILL.md body** - In context whenever skill triggers (<500 lines ideal)
3. **Bundled resources** - As needed (unlimited, scripts can execute without loading)

These word counts are approximate and you can feel free to go longer if needed.

**Key patterns:**
- Keep SKILL.md under 500 lines; if you're approaching this limit, add an additional layer of hierarchy along with clear pointers about where the model using the skill should go next to follow up.
- Reference files clearly from SKILL.md with guidance on when to read them
- For large reference files (>300 lines), include a table of contents

**Domain organization**: When a skill supports multiple domains/frameworks, organize by variant:
```
cloud-deploy/
├── SKILL.md (workflow + selection)
└── references/
    ├── aws.md
    ├── gcp.md
    └── azure.md
```
Claude reads only the relevant reference file.

#### Principle of Lack of Surprise

This goes without saying, but skills must not contain malware, exploit code, or any content that could compromise system security. A skill's contents should not surprise the user in their intent if described. Don't go along with requests to create misleading skills or skills designed to facilitate unauthorized access, data exfiltration, or other malicious activities. Things like a "roleplay as an XYZ" are OK though.

#### Writing Patterns

Prefer using the imperative form in instructions.

**Defining output formats** - You can do it like this:
```markdown
## Report structure
ALWAYS use this exact template:
# [Title]
## Executive summary
## Key findings
## Recommendations
```

**Examples pattern** - It's useful to include examples. You can format them like this (but if "Input" and "Output" are in the examples you might want to deviate a little):
```markdown
## Commit message format
**Example 1:**
Input: Added user authentication with JWT tokens
Output: feat(auth): implement JWT-based authentication
```

### Writing Style

Try to explain to the model why things are important in lieu of heavy-handed musty MUSTs. Use theory of mind and try to make the skill general and not super-narrow to specific examples. Start by writing a draft and then look at it with fresh eyes and improve it.

### Test Cases

After writing the skill draft, come up with 2-3 realistic test prompts — the kind of thing a real user would actually say. Share them with the user: [you don't have to use this exact language] "Here are a few test cases I'd like to try. Do these look right, or do you want to add more?" Then run them.

Save test cases to `evals/evals.json`. Don't write assertions yet — just the prompts. You'll draft assertions in the next step while the runs are in progress.

```json
{
  "skill_name": "example-skill",
  "evals": [
    {
      "id": 1,
      "prompt": "User's task prompt",
      "expected_output": "Description of expected result",
      "files": []
    }
  ]
}
```

See `references/schemas.md` for the full schema (including the `assertions` field, which you'll add later).

## Running and evaluating test cases

This section is one continuous sequence — don't stop partway through. Do NOT use `/skill-test` or any other testing skill.

Put results in `<skill-name>-workspace/` as a sibling to the skill directory. Within the workspace, organize results by iteration (`iteration-1/`, `iteration-2/`, etc.) and within that, each test case gets a directory (`eval-0/`, `eval-1/`, etc.). Don't create all of this upfront — just create directories as you go.

### Step 1: Spawn all runs (with-skill AND baseline) in the same turn

For each test case, spawn two subagents in the same turn — one with the skill, one without. This is important: don't spawn the with-skill runs first and then come back for baselines later. Launch everything at once so it all finishes around the same time.

**With-skill run:**

```
Execute this task:
- Skill path: <path-to-skill>
- Task: <eval prompt>
- Input files: <eval files if any, or "none">
- Save outputs to: <workspace>/iteration-<N>/eval-<ID>/with_skill/outputs/
- Outputs to save: <what the user cares about — e.g., "the .docx file", "the final CSV">
```

**Baseline run** (same prompt, but the baseline depends on context):
- **Creating a new skill**: no skill at all. Same prompt, no skill path, save to `without_skill/outputs/`.
- **Improving an existing skill**: the old version. Before editing, snapshot the skill (`cp -r <skill-path> <workspace>/skill-snapshot/`), then point the baseline subagent at the snapshot. Save to `old_skill/outputs/`.

Write an `eval_metadata.json` for each test case (assertions can be empty for now). Give each eval a descriptive name based on what it's testing — not just "eval-0". Use this name for the directory too. If this iteration uses new or modified eval prompts, create these files for each new eval directory — don't assume they carry over from previous iterations.

```json
{
  "eval_id": 0,
  "eval_name": "descriptive-name-here",
  "prompt": "The user's task prompt",
  "assertions": []
}
```

### Step 2: While runs are in progress, draft assertions

Don't just wait for the runs to finish — you can use this time productively. Draft quantitative assertions for each test case and explain them to the user. If assertions already exist in `evals/evals.json`, review them and explain what they check.

Good assertions are objectively verifiable and have descriptive names — they should read clearly in the benchmark viewer so someone glancing at the results immediately understands what each one checks. Subjective skills (writing style, design quality) are better evaluated qualitatively — don't force assertions onto things that need human judgment.

Update the `eval_metadata.json` files and `evals/evals.json` with the assertions once drafted. Also explain to the user what they'll see in the viewer — both the qualitative outputs and the quantitative benchmark.

### Step 3: As runs complete, capture timing data

When each subagent task completes, you receive a notification containing `total_tokens` and `duration_ms`. Save this data immediately to `timing.json` in the run directory:

```json
{
  "total_tokens": 84852,
  "duration_ms": 23332,
  "total_duration_seconds": 23.3
}
```

This is the only opportunity to capture this data — it comes through the task notification and isn't persisted elsewhere. Process each notification as it arrives rather than trying to batch them.

### Step 4: Grade, aggregate, and launch the viewer

Once all runs are done:

1. **Grade each run** — spawn a grader subagent (or grade inline) that reads `agents/grader.md` and evaluates each assertion against the outputs. Save results to `grading.json` in each run directory. The grading.json expectations array must use the fields `text`, `passed`, and `evidence` (not `name`/`met`/`details` or other variants) — the viewer depends on these exact field names. For assertions that can be checked programmatically, write and run a script rather than eyeballing it — scripts are faster, more reliable, and can be reused across iterations.

2. **Aggregate into benchmark** — run the aggregation script from the skill-creator directory:
   ```bash
   python -m scripts.aggregate_benchmark <workspace>/iteration-N --skill-name <name>
   ```
   This produces `benchmark.json` and `benchmark.md` with pass_rate, time, and tokens for each configuration, with mean ± stddev and the delta. If generating benchmark.json manually, see `references/schemas.md` for the exact schema the viewer expects.
Put each with_skill version before its baseline counterpart.

3. **Do an analyst pass** — read the benchmark data and surface patterns the aggregate stats might hide. See `agents/analyzer.md` (the "Analyzing Benchmark Results" section) for what to look for — things like assertions that always pass regardless of skill (non-discriminating), high-variance evals (possibly flaky), and time/token tradeoffs.

4. **Launch the viewer** with both qualitative outputs and quantitative data:
   ```bash
   nohup python <skill-creator-path>/eval-viewer/generate_review.py \
     <workspace>/iteration-N \
     --skill-name "my-skill" \
     --benchmark <workspace>/iteration-N/benchmark.json \
     > /dev/null 2>&1 &
   VIEWER_PID=$!
   ```
   For iteration 2+, also pass `--previous-workspace <workspace>/iteration-<N-1>`.

   **Cowork / headless environments:** If `webbrowser.open()` is not available or the environment has no display, use `--static <output_path>` to write a standalone HTML file instead of starting a server. Feedback will be downloaded as a `feedback.json` file when the user clicks "Submit All Reviews". After download, copy `feedback.json` into the workspace directory for the next iteration to pick up.

Note: please use generate_review.py to create the viewer; there's no need to write custom HTML.

5. **Tell the user** something like: "I've opened the results in your browser. There are two tabs — 'Outputs' lets you click through each test case and leave feedback, 'Benchmark' shows the quantitative comparison. When you're done, come back here and let me know."

### What the user sees in the viewer

The "Outputs" tab shows one test case at a time:
- **Prompt**: the task that was given
- **Output**: the files the skill produced, rendered inline where possible
- **Previous Output** (iteration 2+): collapsed section showing last iteration's output
- **Formal Grades** (if grading was run): collapsed section showing assertion pass/fail
- **Feedback**: a textbox that auto-saves as they type
- **Previous Feedback** (iteration 2+): their comments from last time, shown below the textbox

The "Benchmark" tab shows the stats summary: pass rates, timing, and token usage for each configuration, with per-eval breakdowns and analyst observations.

Navigation is via prev/next buttons or arrow keys. When done, they click "Submit All Reviews" which saves all feedback to `feedback.json`.

### Step 5: Read the feedback

When the user tells you they're done, read `feedback.json`:

```json
{
  "reviews": [
    {"run_id": "eval-0-with_skill", "feedback": "the chart is missing axis labels", "timestamp": "..."},
    {"run_id": "eval-1-with_skill", "feedback": "", "timestamp": "..."},
    {"run_id": "eval-2-with_skill", "feedback": "perfect, love this", "timestamp": "..."}
  ],
  "status": "complete"
}
```

Empty feedback means the user thought it was fine. Focus your improvements on the test cases where the user had specific complaints.

Kill the viewer server when you're done with it:

```bash
kill $VIEWER_PID 2>/dev/null
```

---

## Improving the skill

This is the heart of the loop. You've run the test cases, the user has reviewed the results, and now you need to make the skill better based on their feedback.

### How to think about improvements

1. **Generalize from the feedback.** The big picture thing that's happening here is that we're trying to create skills that can be used a million times (maybe literally, maybe even more who knows) across many different prompts. Here you and the user are iterating on only a few examples over and over again because it helps move faster. The user knows these examples in and out and it's quick for them to assess new outputs. But if the skill you and the user are codeveloping works only for those examples, it's useless. Rather than put in fiddly overfitty changes, or oppressively constrictive MUSTs, if there's some stubborn issue, you might try branching out and using different metaphors, or recommending different patterns of working. It's relatively cheap to try and maybe you'll land on something great.

2. **Keep the prompt lean.** Remove things that aren't pulling their weight. Make sure to read the transcripts, not just the final outputs — if it looks like the skill is making the model waste a bunch of time doing things that are unproductive, you can try getting rid of the parts of the skill that are making it do that and seeing what happens.

3. **Explain the why.** Try hard to explain the **why** behind everything you're asking the model to do. Today's LLMs are *smart*. They have good theory of mind and when given a good harness can go beyond rote instructions and really make things happen. Even if the feedback from the user is terse or frustrated, try to actually understand the task and why the user is writing what they wrote, and what they actually wrote, and then transmit this understanding into the instructions. If you find yourself writing ALWAYS or NEVER in all caps, or using super rigid structures, that's a yellow flag — if possible, reframe and explain the reasoning so that the model understands why the thing you're asking for is important. That's a more humane, powerful, and effective approach.

4. **Look for repeated work across test cases.** Read the transcripts from the test runs and notice if the subagents all independently wrote similar helper scripts or took the same multi-step approach to something. If all 3 test cases resulted in the subagent writing a `create_docx.py` or a `build_chart.py`, that's a strong signal the skill should bundle that script. Write it once, put it in `scripts/`, and tell the skill to use it. This saves every future invocation from reinventing the wheel.

This task is pretty important (we are trying to create billions a year in economic value here!) and your thinking time is not the blocker; take your time and really mull things over. I'd suggest writing a draft revision and then looking at it anew and making improvements. Really do your best to get into the head of the user and understand what they want and need.

### The iteration loop

After improving the skill:

1. Apply your improvements to the skill
2. Rerun all test cases into a new `iteration-<N+1>/` directory, including baseline runs. If you're creating a new skill, the baseline is always `without_skill` (no skill) — that stays the same across iterations. If you're improving an existing skill, use your judgment on what makes sense as the baseline: the original version the user came in with, or the previous iteration.
3. Launch the reviewer with `--previous-workspace` pointing at the previous iteration
4. Wait for the user to review and tell you they're done
5. Read the new feedback, improve again, repeat

Keep going until:
- The user says they're happy
- The feedback is all empty (everything looks good)
- You're not making meaningful progress

---

## Advanced: Blind comparison

For situations where you want a more rigorous comparison between two versions of a skill (e.g., the user asks "is the new version actually better?"), there's a blind comparison system. Read `agents/comparator.md` and `agents/analyzer.md` for the details. The basic idea is: give two outputs to an independent agent without telling it which is which, and let it judge quality. Then analyze why the winner won.

This is optional, requires subagents, and most users won't need it. The human review loop is usually sufficient.

---

## Description Optimization

The description field in SKILL.md frontmatter is the primary mechanism that determines whether Claude invokes a skill. After creating or improving a skill, offer to optimize the description for better triggering accuracy.

### Step 1: Generate trigger eval queries

Create 20 eval queries — a mix of should-trigger and should-not-trigger. Save as JSON:

```json
[
  {"query": "the user prompt", "should_trigger": true},
  {"query": "another prompt", "should_trigger": false}
]
```

The queries must be realistic and something a Claude Code or Claude.ai user would actually type. Not abstract requests, but requests that are concrete and specific and have a good amount of detail. For instance, file paths, personal context about the user's job or situation, column names and values, company names, URLs. A little bit of backstory. Some might be in lowercase or contain abbreviations or typos or casual speech. Use a mix of different lengths, and focus on edge cases rather than making them clear-cut (the user will get a chance to sign off on them).

Bad: `"Format this data"`, `"Extract text from PDF"`, `"Create a chart"`

Good: `"ok so my boss just sent me this xlsx file (its in my downloads, called something like 'Q4 sales final FINAL v2.xlsx') and she wants me to add a column that shows the profit margin as a percentage. The revenue is in column C and costs are in column D i think"`

For the **should-trigger** queries (8-10), think about coverage. You want different phrasings of the same intent — some formal, some casual. Include cases where the user doesn't explicitly name the skill or file type but clearly needs it. Throw in some uncommon use cases and cases where this skill competes with another but should win.

For the **should-not-trigger** queries (8-10), the most valuable ones are the near-misses — queries that share keywords or concepts with the skill but actually need something different. Think adjacent domains, ambiguous phrasing where a naive keyword match would trigger but shouldn't, and cases where the query touches on something the skill does but in a context where another tool is more appropriate.

The key thing to avoid: don't make should-not-trigger queries obviously irrelevant. "Write a fibonacci function" as a negative test for a PDF skill is too easy — it doesn't test anything. The negative cases should be genuinely tricky.

### Step 2: Review with user

Present the eval set to the user for review using the HTML template:

1. Read the template from `assets/eval_review.html`
2. Replace the placeholders:
   - `__EVAL_DATA_PLACEHOLDER__` → the JSON array of eval items (no quotes around it — it's a JS variable assignment)
   - `__SKILL_NAME_PLACEHOLDER__` → the skill's name
   - `__SKILL_DESCRIPTION_PLACEHOLDER__` → the skill's current description
3. Write to a temp file (e.g., `/tmp/eval_review_<skill-name>.html`) and open it: `open /tmp/eval_review_<skill-name>.html`
4. The user can edit queries, toggle should-trigger, add/remove entries, then click "Export Eval Set"
5. The file downloads to `~/Downloads/eval_set.json` — check the Downloads folder for the most recent version in case there are multiple (e.g., `eval_set (1).json`)

This step matters — bad eval queries lead to bad descriptions.

### Step 3: Run the optimization loop

Tell the user: "This will take some time — I'll run the optimization loop in the background and check on it periodically."

Save the eval set to the workspace, then run in the background:

```bash
python -m scripts.run_loop \
  --eval-set <path-to-trigger-eval.json> \
  --skill-path <path-to-skill> \
  --model <model-id-powering-this-session> \
  --max-iterations 5 \
  --verbose
```

Use the model ID from your system prompt (the one powering the current session) so the triggering test matches what the user actually experiences.

While it runs, periodically tail the output to give the user updates on which iteration it's on and what the scores look like.

This handles the full optimization loop automatically. It splits the eval set into 60% train and 40% held-out test, evaluates the current description (running each query 3 times to get a reliable trigger rate), then calls Claude to propose improvements based on what failed. It re-evaluates each new description on both train and test, iterating up to 5 times. When it's done, it opens an HTML report in the browser showing the results per iteration and returns JSON with `best_description` — selected by test score rather than train score to avoid overfitting.

### How skill triggering works

Understanding the triggering mechanism helps design better eval queries. Skills appear in Claude's `available_skills` list with their name + description, and Claude decides whether to consult a skill based on that description. The important thing to know is that Claude only consults skills for tasks it can't easily handle on its own — simple, one-step queries like "read this PDF" may not trigger a skill even if the description matches perfectly, because Claude can handle them directly with basic tools. Complex, multi-step, or specialized queries reliably trigger skills when the description matches.

This means your eval queries should be substantive enough that Claude would actually benefit from consulting a skill. Simple queries like "read file X" are poor test cases — they won't trigger skills regardless of description quality.

### Step 4: Apply the result

Take `best_description` from the JSON output and update the skill's SKILL.md frontmatter. Show the user before/after and report the scores.

---

### Package and Present (only if `present_files` tool is available)

Check whether you have access to the `present_files` tool. If you don't, skip this step. If you do, package the skill and present the .skill file to the user:

```bash
python -m scripts.package_skill <path/to/skill-folder>
```

After packaging, direct the user to the resulting `.skill` file path so they can install it.

---

## Claude.ai-specific instructions

In Claude.ai, the core workflow is the same (draft → test → review → improve → repeat), but because Claude.ai doesn't have subagents, some mechanics change. Here's what to adapt:

**Running test cases**: No subagents means no parallel execution. For each test case, read the skill's SKILL.md, then follow its instructions to accomplish the test prompt yourself. Do them one at a time. This is less rigorous than independent subagents (you wrote the skill and you're also running it, so you have full context), but it's a useful sanity check — and the human review step compensates. Skip the baseline runs — just use the skill to complete the task as requested.

**Reviewing results**: If you can't open a browser (e.g., Claude.ai's VM has no display, or you're on a remote server), skip the browser reviewer entirely. Instead, present results directly in the conversation. For each test case, show the prompt and the output. If the output is a file the user needs to see (like a .docx or .xlsx), save it to the filesystem and tell them where it is so they can download and inspect it. Ask for feedback inline: "How does this look? Anything you'd change?"

**Benchmarking**: Skip the quantitative benchmarking — it relies on baseline comparisons which aren't meaningful without subagents. Focus on qualitative feedback from the user.

**The iteration loop**: Same as before — improve the skill, rerun the test cases, ask for feedback — just without the browser reviewer in the middle. You can still organize results into iteration directories on the filesystem if you have one.

**Description optimization**: This section requires the `claude` CLI tool (specifically `claude -p`) which is only available in Claude Code. Skip it if you're on Claude.ai.

**Blind comparison**: Requires subagents. Skip it.

**Packaging**: The `package_skill.py` script works anywhere with Python and a filesystem. On Claude.ai, you can run it and the user can download the resulting `.skill` file.

**Updating an existing skill**: The user might be asking you to update an existing skill, not create a new one. In this case:
- **Preserve the original name.** Note the skill's directory name and `name` frontmatter field -- use them unchanged. E.g., if the installed skill is `research-helper`, output `research-helper.skill` (not `research-helper-v2`).
- **Copy to a writeable location before editing.** The installed skill path may be read-only. Copy to `/tmp/skill-name/`, edit there, and package from the copy.
- **If packaging manually, stage in `/tmp/` first**, then copy to the output directory -- direct writes may fail due to permissions.

---

## Cowork-Specific Instructions

If you're in Cowork, the main things to know are:

- You have subagents, so the main workflow (spawn test cases in parallel, run baselines, grade, etc.) all works. (However, if you run into severe problems with timeouts, it's OK to run the test prompts in series rather than parallel.)
- You don't have a browser or display, so when generating the eval viewer, use `--static <output_path>` to write a standalone HTML file instead of starting a server. Then proffer a link that the user can click to open the HTML in their browser.
- For whatever reason, the Cowork setup seems to disincline Claude from generating the eval viewer after running the tests, so just to reiterate: whether you're in Cowork or in Claude Code, after running tests, you should always generate the eval viewer for the human to look at examples before revising the skill yourself and trying to make corrections, using `generate_review.py` (not writing your own boutique html code). Sorry in advance but I'm gonna go all caps here: GENERATE THE EVAL VIEWER *BEFORE* evaluating inputs yourself. You want to get them in front of the human ASAP!
- Feedback works differently: since there's no running server, the viewer's "Submit All Reviews" button will download `feedback.json` as a file. You can then read it from there (you may have to request access first).
- Packaging works — `package_skill.py` just needs Python and a filesystem.
- Description optimization (`run_loop.py` / `run_eval.py`) should work in Cowork just fine since it uses `claude -p` via subprocess, not a browser, but please save it until you've fully finished making the skill and the user agrees it's in good shape.
- **Updating an existing skill**: The user might be asking you to update an existing skill, not create a new one. Follow the update guidance in the claude.ai section above.

---

## Reference files

The agents/ directory contains instructions for specialized subagents. Read them when you need to spawn the relevant subagent.

- `agents/grader.md` — How to evaluate assertions against outputs
- `agents/comparator.md` — How to do blind A/B comparison between two outputs
- `agents/analyzer.md` — How to analyze why one version beat another

The references/ directory has additional documentation:
- `references/schemas.md` — JSON structures for evals.json, grading.json, etc.

---

Repeating one more time the core loop here for emphasis:

- Figure out what the skill is about
- Draft or edit the skill
- Run claude-with-access-to-the-skill on test prompts
- With the user, evaluate the outputs:
  - Create benchmark.json and run `eval-viewer/generate_review.py` to help the user review them
  - Run quantitative evals
- Repeat until you and the user are satisfied
- Package the final skill and return it to the user.

Please add steps to your TodoList, if you have such a thing, to make sure you don't forget. If you're in Cowork, please specifically put "Create evals JSON and run `eval-viewer/generate_review.py` so human can review test cases" in your TodoList to make sure it happens.

Good luck!

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:agents/analyzer.md
# Post-hoc Analyzer Agent

Analyze blind comparison results to understand WHY the winner won and generate improvement suggestions.

## Role

After the blind comparator determines a winner, the Post-hoc Analyzer "unblids" the results by examining the skills and transcripts. The goal is to extract actionable insights: what made the winner better, and how can the loser be improved?

## Inputs

You receive these parameters in your prompt:

- **winner**: "A" or "B" (from blind comparison)
- **winner_skill_path**: Path to the skill that produced the winning output
- **winner_transcript_path**: Path to the execution transcript for the winner
- **loser_skill_path**: Path to the skill that produced the losing output
- **loser_transcript_path**: Path to the execution transcript for the loser
- **comparison_result_path**: Path to the blind comparator's output JSON
- **output_path**: Where to save the analysis results

## Process

### Step 1: Read Comparison Result

1. Read the blind comparator's output at comparison_result_path
2. Note the winning side (A or B), the reasoning, and any scores
3. Understand what the comparator valued in the winning output

### Step 2: Read Both Skills

1. Read the winner skill's SKILL.md and key referenced files
2. Read the loser skill's SKILL.md and key referenced files
3. Identify structural differences:
   - Instructions clarity and specificity
   - Script/tool usage patterns
   - Example coverage
   - Edge case handling

### Step 3: Read Both Transcripts

1. Read the winner's transcript
2. Read the loser's transcript
3. Compare execution patterns:
   - How closely did each follow their skill's instructions?
   - What tools were used differently?
   - Where did the loser diverge from optimal behavior?
   - Did either encounter errors or make recovery attempts?

### Step 4: Analyze Instruction Following

For each transcript, evaluate:
- Did the agent follow the skill's explicit instructions?
- Did the agent use the skill's provided tools/scripts?
- Were there missed opportunities to leverage skill content?
- Did the agent add unnecessary steps not in the skill?

Score instruction following 1-10 and note specific issues.

### Step 5: Identify Winner Strengths

Determine what made the winner better:
- Clearer instructions that led to better behavior?
- Better scripts/tools that produced better output?
- More comprehensive examples that guided edge cases?
- Better error handling guidance?

Be specific. Quote from skills/transcripts where relevant.

### Step 6: Identify Loser Weaknesses

Determine what held the loser back:
- Ambiguous instructions that led to suboptimal choices?
- Missing tools/scripts that forced workarounds?
- Gaps in edge case coverage?
- Poor error handling that caused failures?

### Step 7: Generate Improvement Suggestions

Based on the analysis, produce actionable suggestions for improving the loser skill:
- Specific instruction changes to make
- Tools/scripts to add or modify
- Examples to include
- Edge cases to address

Prioritize by impact. Focus on changes that would have changed the outcome.

### Step 8: Write Analysis Results

Save structured analysis to `{output_path}`.

## Output Format

Write a JSON file with this structure:

```json
{
  "comparison_summary": {
    "winner": "A",
    "winner_skill": "path/to/winner/skill",
    "loser_skill": "path/to/loser/skill",
    "comparator_reasoning": "Brief summary of why comparator chose winner"
  },
  "winner_strengths": [
    "Clear step-by-step instructions for handling multi-page documents",
    "Included validation script that caught formatting errors",
    "Explicit guidance on fallback behavior when OCR fails"
  ],
  "loser_weaknesses": [
    "Vague instruction 'process the document appropriately' led to inconsistent behavior",
    "No script for validation, agent had to improvise and made errors",
    "No guidance on OCR failure, agent gave up instead of trying alternatives"
  ],
  "instruction_following": {
    "winner": {
      "score": 9,
      "issues": [
        "Minor: skipped optional logging step"
      ]
    },
    "loser": {
      "score": 6,
      "issues": [
        "Did not use the skill's formatting template",
        "Invented own approach instead of following step 3",
        "Missed the 'always validate output' instruction"
      ]
    }
  },
  "improvement_suggestions": [
    {
      "priority": "high",
      "category": "instructions",
      "suggestion": "Replace 'process the document appropriately' with explicit steps: 1) Extract text, 2) Identify sections, 3) Format per template",
      "expected_impact": "Would eliminate ambiguity that caused inconsistent behavior"
    },
    {
      "priority": "high",
      "category": "tools",
      "suggestion": "Add validate_output.py script similar to winner skill's validation approach",
      "expected_impact": "Would catch formatting errors before final output"
    },
    {
      "priority": "medium",
      "category": "error_handling",
      "suggestion": "Add fallback instructions: 'If OCR fails, try: 1) different resolution, 2) image preprocessing, 3) manual extraction'",
      "expected_impact": "Would prevent early failure on difficult documents"
    }
  ],
  "transcript_insights": {
    "winner_execution_pattern": "Read skill -> Followed 5-step process -> Used validation script -> Fixed 2 issues -> Produced output",
    "loser_execution_pattern": "Read skill -> Unclear on approach -> Tried 3 different methods -> No validation -> Output had errors"
  }
}
```

## Guidelines

- **Be specific**: Quote from skills and transcripts, don't just say "instructions were unclear"
- **Be actionable**: Suggestions should be concrete changes, not vague advice
- **Focus on skill improvements**: The goal is to improve the losing skill, not critique the agent
- **Prioritize by impact**: Which changes would most likely have changed the outcome?
- **Consider causation**: Did the skill weakness actually cause the worse output, or is it incidental?
- **Stay objective**: Analyze what happened, don't editorialize
- **Think about generalization**: Would this improvement help on other evals too?

## Categories for Suggestions

Use these categories to organize improvement suggestions:

| Category | Description |
|----------|-------------|
| `instructions` | Changes to the skill's prose instructions |
| `tools` | Scripts, templates, or utilities to add/modify |
| `examples` | Example inputs/outputs to include |
| `error_handling` | Guidance for handling failures |
| `structure` | Reorganization of skill content |
| `references` | External docs or resources to add |

## Priority Levels

- **high**: Would likely change the outcome of this comparison
- **medium**: Would improve quality but may not change win/loss
- **low**: Nice to have, marginal improvement

---

# Analyzing Benchmark Results

When analyzing benchmark results, the analyzer's purpose is to **surface patterns and anomalies** across multiple runs, not suggest skill improvements.

## Role

Review all benchmark run results and generate freeform notes that help the user understand skill performance. Focus on patterns that wouldn't be visible from aggregate metrics alone.

## Inputs

You receive these parameters in your prompt:

- **benchmark_data_path**: Path to the in-progress benchmark.json with all run results
- **skill_path**: Path to the skill being benchmarked
- **output_path**: Where to save the notes (as JSON array of strings)

## Process

### Step 1: Read Benchmark Data

1. Read the benchmark.json containing all run results
2. Note the configurations tested (with_skill, without_skill)
3. Understand the run_summary aggregates already calculated

### Step 2: Analyze Per-Assertion Patterns

For each expectation across all runs:
- Does it **always pass** in both configurations? (may not differentiate skill value)
- Does it **always fail** in both configurations? (may be broken or beyond capability)
- Does it **always pass with skill but fail without**? (skill clearly adds value here)
- Does it **always fail with skill but pass without**? (skill may be hurting)
- Is it **highly variable**? (flaky expectation or non-deterministic behavior)

### Step 3: Analyze Cross-Eval Patterns

Look for patterns across evals:
- Are certain eval types consistently harder/easier?
- Do some evals show high variance while others are stable?
- Are there surprising results that contradict expectations?

### Step 4: Analyze Metrics Patterns

Look at time_seconds, tokens, tool_calls:
- Does the skill significantly increase execution time?
- Is there high variance in resource usage?
- Are there outlier runs that skew the aggregates?

### Step 5: Generate Notes

Write freeform observations as a list of strings. Each note should:
- State a specific observation
- Be grounded in the data (not speculation)
- Help the user understand something the aggregate metrics don't show

Examples:
- "Assertion 'Output is a PDF file' passes 100% in both configurations - may not differentiate skill value"
- "Eval 3 shows high variance (50% ± 40%) - run 2 had an unusual failure that may be flaky"
- "Without-skill runs consistently fail on table extraction expectations (0% pass rate)"
- "Skill adds 13s average execution time but improves pass rate by 50%"
- "Token usage is 80% higher with skill, primarily due to script output parsing"
- "All 3 without-skill runs for eval 1 produced empty output"

### Step 6: Write Notes

Save notes to `{output_path}` as a JSON array of strings:

```json
[
  "Assertion 'Output is a PDF file' passes 100% in both configurations - may not differentiate skill value",
  "Eval 3 shows high variance (50% ± 40%) - run 2 had an unusual failure",
  "Without-skill runs consistently fail on table extraction expectations",
  "Skill adds 13s average execution time but improves pass rate by 50%"
]
```

## Guidelines

**DO:**
- Report what you observe in the data
- Be specific about which evals, expectations, or runs you're referring to
- Note patterns that aggregate metrics would hide
- Provide context that helps interpret the numbers

**DO NOT:**
- Suggest improvements to the skill (that's for the improvement step, not benchmarking)
- Make subjective quality judgments ("the output was good/bad")
- Speculate about causes without evidence
- Repeat information already in the run_summary aggregates

FILE:agents/comparator.md
# Blind Comparator Agent

Compare two outputs WITHOUT knowing which skill produced them.

## Role

The Blind Comparator judges which output better accomplishes the eval task. You receive two outputs labeled A and B, but you do NOT know which skill produced which. This prevents bias toward a particular skill or approach.

Your judgment is based purely on output quality and task completion.

## Inputs

You receive these parameters in your prompt:

- **output_a_path**: Path to the first output file or directory
- **output_b_path**: Path to the second output file or directory
- **eval_prompt**: The original task/prompt that was executed
- **expectations**: List of expectations to check (optional - may be empty)

## Process

### Step 1: Read Both Outputs

1. Examine output A (file or directory)
2. Examine output B (file or directory)
3. Note the type, structure, and content of each
4. If outputs are directories, examine all relevant files inside

### Step 2: Understand the Task

1. Read the eval_prompt carefully
2. Identify what the task requires:
   - What should be produced?
   - What qualities matter (accuracy, completeness, format)?
   - What would distinguish a good output from a poor one?

### Step 3: Generate Evaluation Rubric

Based on the task, generate a rubric with two dimensions:

**Content Rubric** (what the output contains):
| Criterion | 1 (Poor) | 3 (Acceptable) | 5 (Excellent) |
|-----------|----------|----------------|---------------|
| Correctness | Major errors | Minor errors | Fully correct |
| Completeness | Missing key elements | Mostly complete | All elements present |
| Accuracy | Significant inaccuracies | Minor inaccuracies | Accurate throughout |

**Structure Rubric** (how the output is organized):
| Criterion | 1 (Poor) | 3 (Acceptable) | 5 (Excellent) |
|-----------|----------|----------------|---------------|
| Organization | Disorganized | Reasonably organized | Clear, logical structure |
| Formatting | Inconsistent/broken | Mostly consistent | Professional, polished |
| Usability | Difficult to use | Usable with effort | Easy to use |

Adapt criteria to the specific task. For example:
- PDF form → "Field alignment", "Text readability", "Data placement"
- Document → "Section structure", "Heading hierarchy", "Paragraph flow"
- Data output → "Schema correctness", "Data types", "Completeness"

### Step 4: Evaluate Each Output Against the Rubric

For each output (A and B):

1. **Score each criterion** on the rubric (1-5 scale)
2. **Calculate dimension totals**: Content score, Structure score
3. **Calculate overall score**: Average of dimension scores, scaled to 1-10

### Step 5: Check Assertions (if provided)

If expectations are provided:

1. Check each expectation against output A
2. Check each expectation against output B
3. Count pass rates for each output
4. Use expectation scores as secondary evidence (not the primary decision factor)

### Step 6: Determine the Winner

Compare A and B based on (in priority order):

1. **Primary**: Overall rubric score (content + structure)
2. **Secondary**: Assertion pass rates (if applicable)
3. **Tiebreaker**: If truly equal, declare a TIE

Be decisive - ties should be rare. One output is usually better, even if marginally.

### Step 7: Write Comparison Results

Save results to a JSON file at the path specified (or `comparison.json` if not specified).

## Output Format

Write a JSON file with this structure:

```json
{
  "winner": "A",
  "reasoning": "Output A provides a complete solution with proper formatting and all required fields. Output B is missing the date field and has formatting inconsistencies.",
  "rubric": {
    "A": {
      "content": {
        "correctness": 5,
        "completeness": 5,
        "accuracy": 4
      },
      "structure": {
        "organization": 4,
        "formatting": 5,
        "usability": 4
      },
      "content_score": 4.7,
      "structure_score": 4.3,
      "overall_score": 9.0
    },
    "B": {
      "content": {
        "correctness": 3,
        "completeness": 2,
        "accuracy": 3
      },
      "structure": {
        "organization": 3,
        "formatting": 2,
        "usability": 3
      },
      "content_score": 2.7,
      "structure_score": 2.7,
      "overall_score": 5.4
    }
  },
  "output_quality": {
    "A": {
      "score": 9,
      "strengths": ["Complete solution", "Well-formatted", "All fields present"],
      "weaknesses": ["Minor style inconsistency in header"]
    },
    "B": {
      "score": 5,
      "strengths": ["Readable output", "Correct basic structure"],
      "weaknesses": ["Missing date field", "Formatting inconsistencies", "Partial data extraction"]
    }
  },
  "expectation_results": {
    "A": {
      "passed": 4,
      "total": 5,
      "pass_rate": 0.80,
      "details": [
        {"text": "Output includes name", "passed": true},
        {"text": "Output includes date", "passed": true},
        {"text": "Format is PDF", "passed": true},
        {"text": "Contains signature", "passed": false},
        {"text": "Readable text", "passed": true}
      ]
    },
    "B": {
      "passed": 3,
      "total": 5,
      "pass_rate": 0.60,
      "details": [
        {"text": "Output includes name", "passed": true},
        {"text": "Output includes date", "passed": false},
        {"text": "Format is PDF", "passed": true},
        {"text": "Contains signature", "passed": false},
        {"text": "Readable text", "passed": true}
      ]
    }
  }
}
```

If no expectations were provided, omit the `expectation_results` field entirely.

## Field Descriptions

- **winner**: "A", "B", or "TIE"
- **reasoning**: Clear explanation of why the winner was chosen (or why it's a tie)
- **rubric**: Structured rubric evaluation for each output
  - **content**: Scores for content criteria (correctness, completeness, accuracy)
  - **structure**: Scores for structure criteria (organization, formatting, usability)
  - **content_score**: Average of content criteria (1-5)
  - **structure_score**: Average of structure criteria (1-5)
  - **overall_score**: Combined score scaled to 1-10
- **output_quality**: Summary quality assessment
  - **score**: 1-10 rating (should match rubric overall_score)
  - **strengths**: List of positive aspects
  - **weaknesses**: List of issues or shortcomings
- **expectation_results**: (Only if expectations provided)
  - **passed**: Number of expectations that passed
  - **total**: Total number of expectations
  - **pass_rate**: Fraction passed (0.0 to 1.0)
  - **details**: Individual expectation results

## Guidelines

- **Stay blind**: DO NOT try to infer which skill produced which output. Judge purely on output quality.
- **Be specific**: Cite specific examples when explaining strengths and weaknesses.
- **Be decisive**: Choose a winner unless outputs are genuinely equivalent.
- **Output quality first**: Assertion scores are secondary to overall task completion.
- **Be objective**: Don't favor outputs based on style preferences; focus on correctness and completeness.
- **Explain your reasoning**: The reasoning field should make it clear why you chose the winner.
- **Handle edge cases**: If both outputs fail, pick the one that fails less badly. If both are excellent, pick the one that's marginally better.

FILE:agents/grader.md
# Grader Agent

Evaluate expectations against an execution transcript and outputs.

## Role

The Grader reviews a transcript and output files, then determines whether each expectation passes or fails. Provide clear evidence for each judgment.

You have two jobs: grade the outputs, and critique the evals themselves. A passing grade on a weak assertion is worse than useless — it creates false confidence. When you notice an assertion that's trivially satisfied, or an important outcome that no assertion checks, say so.

## Inputs

You receive these parameters in your prompt:

- **expectations**: List of expectations to evaluate (strings)
- **transcript_path**: Path to the execution transcript (markdown file)
- **outputs_dir**: Directory containing output files from execution

## Process

### Step 1: Read the Transcript

1. Read the transcript file completely
2. Note the eval prompt, execution steps, and final result
3. Identify any issues or errors documented

### Step 2: Examine Output Files

1. List files in outputs_dir
2. Read/examine each file relevant to the expectations. If outputs aren't plain text, use the inspection tools provided in your prompt — don't rely solely on what the transcript says the executor produced.
3. Note contents, structure, and quality

### Step 3: Evaluate Each Assertion

For each expectation:

1. **Search for evidence** in the transcript and outputs
2. **Determine verdict**:
   - **PASS**: Clear evidence the expectation is true AND the evidence reflects genuine task completion, not just surface-level compliance
   - **FAIL**: No evidence, or evidence contradicts the expectation, or the evidence is superficial (e.g., correct filename but empty/wrong content)
3. **Cite the evidence**: Quote the specific text or describe what you found

### Step 4: Extract and Verify Claims

Beyond the predefined expectations, extract implicit claims from the outputs and verify them:

1. **Extract claims** from the transcript and outputs:
   - Factual statements ("The form has 12 fields")
   - Process claims ("Used pypdf to fill the form")
   - Quality claims ("All fields were filled correctly")

2. **Verify each claim**:
   - **Factual claims**: Can be checked against the outputs or external sources
   - **Process claims**: Can be verified from the transcript
   - **Quality claims**: Evaluate whether the claim is justified

3. **Flag unverifiable claims**: Note claims that cannot be verified with available information

This catches issues that predefined expectations might miss.

### Step 5: Read User Notes

If `{outputs_dir}/user_notes.md` exists:
1. Read it and note any uncertainties or issues flagged by the executor
2. Include relevant concerns in the grading output
3. These may reveal problems even when expectations pass

### Step 6: Critique the Evals

After grading, consider whether the evals themselves could be improved. Only surface suggestions when there's a clear gap.

Good suggestions test meaningful outcomes — assertions that are hard to satisfy without actually doing the work correctly. Think about what makes an assertion *discriminating*: it passes when the skill genuinely succeeds and fails when it doesn't.

Suggestions worth raising:
- An assertion that passed but would also pass for a clearly wrong output (e.g., checking filename existence but not file content)
- An important outcome you observed — good or bad — that no assertion covers at all
- An assertion that can't actually be verified from the available outputs

Keep the bar high. The goal is to flag things the eval author would say "good catch" about, not to nitpick every assertion.

### Step 7: Write Grading Results

Save results to `{outputs_dir}/../grading.json` (sibling to outputs_dir).

## Grading Criteria

**PASS when**:
- The transcript or outputs clearly demonstrate the expectation is true
- Specific evidence can be cited
- The evidence reflects genuine substance, not just surface compliance (e.g., a file exists AND contains correct content, not just the right filename)

**FAIL when**:
- No evidence found for the expectation
- Evidence contradicts the expectation
- The expectation cannot be verified from available information
- The evidence is superficial — the assertion is technically satisfied but the underlying task outcome is wrong or incomplete
- The output appears to meet the assertion by coincidence rather than by actually doing the work

**When uncertain**: The burden of proof to pass is on the expectation.

### Step 8: Read Executor Metrics and Timing

1. If `{outputs_dir}/metrics.json` exists, read it and include in grading output
2. If `{outputs_dir}/../timing.json` exists, read it and include timing data

## Output Format

Write a JSON file with this structure:

```json
{
  "expectations": [
    {
      "text": "The output includes the name 'John Smith'",
      "passed": true,
      "evidence": "Found in transcript Step 3: 'Extracted names: John Smith, Sarah Johnson'"
    },
    {
      "text": "The spreadsheet has a SUM formula in cell B10",
      "passed": false,
      "evidence": "No spreadsheet was created. The output was a text file."
    },
    {
      "text": "The assistant used the skill's OCR script",
      "passed": true,
      "evidence": "Transcript Step 2 shows: 'Tool: Bash - python ocr_script.py image.png'"
    }
  ],
  "summary": {
    "passed": 2,
    "failed": 1,
    "total": 3,
    "pass_rate": 0.67
  },
  "execution_metrics": {
    "tool_calls": {
      "Read": 5,
      "Write": 2,
      "Bash": 8
    },
    "total_tool_calls": 15,
    "total_steps": 6,
    "errors_encountered": 0,
    "output_chars": 12450,
    "transcript_chars": 3200
  },
  "timing": {
    "executor_duration_seconds": 165.0,
    "grader_duration_seconds": 26.0,
    "total_duration_seconds": 191.0
  },
  "claims": [
    {
      "claim": "The form has 12 fillable fields",
      "type": "factual",
      "verified": true,
      "evidence": "Counted 12 fields in field_info.json"
    },
    {
      "claim": "All required fields were populated",
      "type": "quality",
      "verified": false,
      "evidence": "Reference section was left blank despite data being available"
    }
  ],
  "user_notes_summary": {
    "uncertainties": ["Used 2023 data, may be stale"],
    "needs_review": [],
    "workarounds": ["Fell back to text overlay for non-fillable fields"]
  },
  "eval_feedback": {
    "suggestions": [
      {
        "assertion": "The output includes the name 'John Smith'",
        "reason": "A hallucinated document that mentions the name would also pass — consider checking it appears as the primary contact with matching phone and email from the input"
      },
      {
        "reason": "No assertion checks whether the extracted phone numbers match the input — I observed incorrect numbers in the output that went uncaught"
      }
    ],
    "overall": "Assertions check presence but not correctness. Consider adding content verification."
  }
}
```

## Field Descriptions

- **expectations**: Array of graded expectations
  - **text**: The original expectation text
  - **passed**: Boolean - true if expectation passes
  - **evidence**: Specific quote or description supporting the verdict
- **summary**: Aggregate statistics
  - **passed**: Count of passed expectations
  - **failed**: Count of failed expectations
  - **total**: Total expectations evaluated
  - **pass_rate**: Fraction passed (0.0 to 1.0)
- **execution_metrics**: Copied from executor's metrics.json (if available)
  - **output_chars**: Total character count of output files (proxy for tokens)
  - **transcript_chars**: Character count of transcript
- **timing**: Wall clock timing from timing.json (if available)
  - **executor_duration_seconds**: Time spent in executor subagent
  - **total_duration_seconds**: Total elapsed time for the run
- **claims**: Extracted and verified claims from the output
  - **claim**: The statement being verified
  - **type**: "factual", "process", or "quality"
  - **verified**: Boolean - whether the claim holds
  - **evidence**: Supporting or contradicting evidence
- **user_notes_summary**: Issues flagged by the executor
  - **uncertainties**: Things the executor wasn't sure about
  - **needs_review**: Items requiring human attention
  - **workarounds**: Places where the skill didn't work as expected
- **eval_feedback**: Improvement suggestions for the evals (only when warranted)
  - **suggestions**: List of concrete suggestions, each with a `reason` and optionally an `assertion` it relates to
  - **overall**: Brief assessment — can be "No suggestions, evals look solid" if nothing to flag

## Guidelines

- **Be objective**: Base verdicts on evidence, not assumptions
- **Be specific**: Quote the exact text that supports your verdict
- **Be thorough**: Check both transcript and output files
- **Be consistent**: Apply the same standard to each expectation
- **Explain failures**: Make it clear why evidence was insufficient
- **No partial credit**: Each expectation is pass or fail, not partial

FILE:assets/eval_review.html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Eval Set Review - __SKILL_NAME_PLACEHOLDER__</title>
  <link rel="preconnect" href="https://fonts.googleapis.com">
  <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
  <link href="https://fonts.googleapis.com/css2?family=Poppins:wght@500;600&family=Lora:wght@400;500&display=swap" rel="stylesheet">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body { font-family: 'Lora', Georgia, serif; background: #faf9f5; padding: 2rem; color: #141413; }
    h1 { font-family: 'Poppins', sans-serif; margin-bottom: 0.5rem; font-size: 1.5rem; }
    .description { color: #b0aea5; margin-bottom: 1.5rem; font-style: italic; max-width: 900px; }
    .controls { margin-bottom: 1rem; display: flex; gap: 0.5rem; }
    .btn { font-family: 'Poppins', sans-serif; padding: 0.5rem 1rem; border: none; border-radius: 6px; cursor: pointer; font-size: 0.875rem; font-weight: 500; }
    .btn-add { background: #6a9bcc; color: white; }
    .btn-add:hover { background: #5889b8; }
    .btn-export { background: #d97757; color: white; }
    .btn-export:hover { background: #c4613f; }
    table { width: 100%; max-width: 1100px; border-collapse: collapse; background: white; border-radius: 6px; overflow: hidden; box-shadow: 0 1px 3px rgba(0,0,0,0.08); }
    th { font-family: 'Poppins', sans-serif; background: #141413; color: #faf9f5; padding: 0.75rem 1rem; text-align: left; font-size: 0.875rem; }
    td { padding: 0.75rem 1rem; border-bottom: 1px solid #e8e6dc; vertical-align: top; }
    tr:nth-child(even) td { background: #faf9f5; }
    tr:hover td { background: #f3f1ea; }
    .section-header td { background: #e8e6dc; font-family: 'Poppins', sans-serif; font-weight: 500; font-size: 0.8rem; color: #141413; text-transform: uppercase; letter-spacing: 0.05em; }
    .query-input { width: 100%; padding: 0.4rem; border: 1px solid #e8e6dc; border-radius: 4px; font-size: 0.875rem; font-family: 'Lora', Georgia, serif; resize: vertical; min-height: 60px; }
    .query-input:focus { outline: none; border-color: #d97757; box-shadow: 0 0 0 2px rgba(217,119,87,0.15); }
    .toggle { position: relative; display: inline-block; width: 44px; height: 24px; }
    .toggle input { opacity: 0; width: 0; height: 0; }
    .toggle .slider { position: absolute; inset: 0; background: #b0aea5; border-radius: 24px; cursor: pointer; transition: 0.2s; }
    .toggle .slider::before { content: ""; position: absolute; width: 18px; height: 18px; left: 3px; bottom: 3px; background: white; border-radius: 50%; transition: 0.2s; }
    .toggle input:checked + .slider { background: #d97757; }
    .toggle input:checked + .slider::before { transform: translateX(20px); }
    .btn-delete { background: #c44; color: white; padding: 0.3rem 0.6rem; border: none; border-radius: 4px; cursor: pointer; font-size: 0.75rem; font-family: 'Poppins', sans-serif; }
    .btn-delete:hover { background: #a33; }
    .summary { margin-top: 1rem; color: #b0aea5; font-size: 0.875rem; }
  </style>
</head>
<body>
  <h1>Eval Set Review: <span id="skill-name">__SKILL_NAME_PLACEHOLDER__</span></h1>
  <p class="description">Current description: <span id="skill-desc">__SKILL_DESCRIPTION_PLACEHOLDER__</span></p>

  <div class="controls">
    <button class="btn btn-add" onclick="addRow()">+ Add Query</button>
    <button class="btn btn-export" onclick="exportEvalSet()">Export Eval Set</button>
  </div>

  <table>
    <thead>
      <tr>
        <th style="width:65%">Query</th>
        <th style="width:18%">Should Trigger</th>
        <th style="width:10%">Actions</th>
      </tr>
    </thead>
    <tbody id="eval-body"></tbody>
  </table>

  <p class="summary" id="summary"></p>

  <script>
    const EVAL_DATA = __EVAL_DATA_PLACEHOLDER__;

    let evalItems = [...EVAL_DATA];

    function render() {
      const tbody = document.getElementById('eval-body');
      tbody.innerHTML = '';

      // Sort: should-trigger first, then should-not-trigger
      const sorted = evalItems
        .map((item, origIdx) => ({ ...item, origIdx }))
        .sort((a, b) => (b.should_trigger ? 1 : 0) - (a.should_trigger ? 1 : 0));

      let lastGroup = null;
      sorted.forEach(item => {
        const group = item.should_trigger ? 'trigger' : 'no-trigger';
        if (group !== lastGroup) {
          const headerRow = document.createElement('tr');
          headerRow.className = 'section-header';
          headerRow.innerHTML = `<td colspan="3">'Should NOT Trigger'</td>`;
          tbody.appendChild(headerRow);
          lastGroup = group;
        }

        const idx = item.origIdx;
        const tr = document.createElement('tr');
        tr.innerHTML = `
          <td><textarea class="query-input" onchange="updateQuery(idx, this.value)">escapeHtml(item.query)</textarea></td>
          <td>
            <label class="toggle">
              <input type="checkbox" '' onchange="updateTrigger(idx, this.checked)">
              <span class="slider"></span>
            </label>
            <span style="margin-left:8px;font-size:0.8rem;color:#b0aea5">'No'</span>
          </td>
          <td><button class="btn-delete" onclick="deleteRow(idx)">Delete</button></td>
        `;
        tbody.appendChild(tr);
      });
      updateSummary();
    }

    function escapeHtml(text) {
      const div = document.createElement('div');
      div.textContent = text;
      return div.innerHTML;
    }

    function updateQuery(idx, value) { evalItems[idx].query = value; updateSummary(); }
    function updateTrigger(idx, value) { evalItems[idx].should_trigger = value; render(); }
    function deleteRow(idx) { evalItems.splice(idx, 1); render(); }

    function addRow() {
      evalItems.push({ query: '', should_trigger: true });
      render();
      const inputs = document.querySelectorAll('.query-input');
      inputs[inputs.length - 1].focus();
    }

    function updateSummary() {
      const trigger = evalItems.filter(i => i.should_trigger).length;
      const noTrigger = evalItems.filter(i => !i.should_trigger).length;
      document.getElementById('summary').textContent =
        `evalItems.length queries total: trigger should trigger, noTrigger should not trigger`;
    }

    function exportEvalSet() {
      const valid = evalItems.filter(i => i.query.trim() !== '');
      const data = valid.map(i => ({ query: i.query.trim(), should_trigger: i.should_trigger }));
      const blob = new Blob([JSON.stringify(data, null, 2)], { type: 'application/json' });
      const url = URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = 'eval_set.json';
      document.body.appendChild(a);
      a.click();
      document.body.removeChild(a);
      URL.revokeObjectURL(url);
    }

    render();
  </script>
</body>
</html>

FILE:eval-viewer/generate_review.py
#!/usr/bin/env python3
"""Generate and serve a review page for eval results.

Reads the workspace directory, discovers runs (directories with outputs/),
embeds all output data into a self-contained HTML page, and serves it via
a tiny HTTP server. Feedback auto-saves to feedback.json in the workspace.

Usage:
    python generate_review.py <workspace-path> [--port PORT] [--skill-name NAME]
    python generate_review.py <workspace-path> --previous-feedback /path/to/old/feedback.json

No dependencies beyond the Python stdlib are required.
"""

import argparse
import base64
import json
import mimetypes
import os
import re
import signal
import subprocess
import sys
import time
import webbrowser
from functools import partial
from http.server import HTTPServer, BaseHTTPRequestHandler
from pathlib import Path

# Files to exclude from output listings
METADATA_FILES = {"transcript.md", "user_notes.md", "metrics.json"}

# Extensions we render as inline text
TEXT_EXTENSIONS = {
    ".txt", ".md", ".json", ".csv", ".py", ".js", ".ts", ".tsx", ".jsx",
    ".yaml", ".yml", ".xml", ".html", ".css", ".sh", ".rb", ".go", ".rs",
    ".java", ".c", ".cpp", ".h", ".hpp", ".sql", ".r", ".toml",
}

# Extensions we render as inline images
IMAGE_EXTENSIONS = {".png", ".jpg", ".jpeg", ".gif", ".svg", ".webp"}

# MIME type overrides for common types
MIME_OVERRIDES = {
    ".svg": "image/svg+xml",
    ".xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    ".docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    ".pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",
}


def get_mime_type(path: Path) -> str:
    ext = path.suffix.lower()
    if ext in MIME_OVERRIDES:
        return MIME_OVERRIDES[ext]
    mime, _ = mimetypes.guess_type(str(path))
    return mime or "application/octet-stream"


def find_runs(workspace: Path) -> list[dict]:
    """Recursively find directories that contain an outputs/ subdirectory."""
    runs: list[dict] = []
    _find_runs_recursive(workspace, workspace, runs)
    runs.sort(key=lambda r: (r.get("eval_id", float("inf")), r["id"]))
    return runs


def _find_runs_recursive(root: Path, current: Path, runs: list[dict]) -> None:
    if not current.is_dir():
        return

    outputs_dir = current / "outputs"
    if outputs_dir.is_dir():
        run = build_run(root, current)
        if run:
            runs.append(run)
        return

    skip = {"node_modules", ".git", "__pycache__", "skill", "inputs"}
    for child in sorted(current.iterdir()):
        if child.is_dir() and child.name not in skip:
            _find_runs_recursive(root, child, runs)


def build_run(root: Path, run_dir: Path) -> dict | None:
    """Build a run dict with prompt, outputs, and grading data."""
    prompt = ""
    eval_id = None

    # Try eval_metadata.json
    for candidate in [run_dir / "eval_metadata.json", run_dir.parent / "eval_metadata.json"]:
        if candidate.exists():
            try:
                metadata = json.loads(candidate.read_text())
                prompt = metadata.get("prompt", "")
                eval_id = metadata.get("eval_id")
            except (json.JSONDecodeError, OSError):
                pass
            if prompt:
                break

    # Fall back to transcript.md
    if not prompt:
        for candidate in [run_dir / "transcript.md", run_dir / "outputs" / "transcript.md"]:
            if candidate.exists():
                try:
                    text = candidate.read_text()
                    match = re.search(r"## Eval Prompt\n\n([\s\S]*?)(?=\n##|$)", text)
                    if match:
                        prompt = match.group(1).strip()
                except OSError:
                    pass
                if prompt:
                    break

    if not prompt:
        prompt = "(No prompt found)"

    run_id = str(run_dir.relative_to(root)).replace("/", "-").replace("\\", "-")

    # Collect output files
    outputs_dir = run_dir / "outputs"
    output_files: list[dict] = []
    if outputs_dir.is_dir():
        for f in sorted(outputs_dir.iterdir()):
            if f.is_file() and f.name not in METADATA_FILES:
                output_files.append(embed_file(f))

    # Load grading if present
    grading = None
    for candidate in [run_dir / "grading.json", run_dir.parent / "grading.json"]:
        if candidate.exists():
            try:
                grading = json.loads(candidate.read_text())
            except (json.JSONDecodeError, OSError):
                pass
            if grading:
                break

    return {
        "id": run_id,
        "prompt": prompt,
        "eval_id": eval_id,
        "outputs": output_files,
        "grading": grading,
    }


def embed_file(path: Path) -> dict:
    """Read a file and return an embedded representation."""
    ext = path.suffix.lower()
    mime = get_mime_type(path)

    if ext in TEXT_EXTENSIONS:
        try:
            content = path.read_text(errors="replace")
        except OSError:
            content = "(Error reading file)"
        return {
            "name": path.name,
            "type": "text",
            "content": content,
        }
    elif ext in IMAGE_EXTENSIONS:
        try:
            raw = path.read_bytes()
            b64 = base64.b64encode(raw).decode("ascii")
        except OSError:
            return {"name": path.name, "type": "error", "content": "(Error reading file)"}
        return {
            "name": path.name,
            "type": "image",
            "mime": mime,
            "data_uri": f"data:{mime};base64,{b64}",
        }
    elif ext == ".pdf":
        try:
            raw = path.read_bytes()
            b64 = base64.b64encode(raw).decode("ascii")
        except OSError:
            return {"name": path.name, "type": "error", "content": "(Error reading file)"}
        return {
            "name": path.name,
            "type": "pdf",
            "data_uri": f"data:{mime};base64,{b64}",
        }
    elif ext == ".xlsx":
        try:
            raw = path.read_bytes()
            b64 = base64.b64encode(raw).decode("ascii")
        except OSError:
            return {"name": path.name, "type": "error", "content": "(Error reading file)"}
        return {
            "name": path.name,
            "type": "xlsx",
            "data_b64": b64,
        }
    else:
        # Binary / unknown — base64 download link
        try:
            raw = path.read_bytes()
            b64 = base64.b64encode(raw).decode("ascii")
        except OSError:
            return {"name": path.name, "type": "error", "content": "(Error reading file)"}
        return {
            "name": path.name,
            "type": "binary",
            "mime": mime,
            "data_uri": f"data:{mime};base64,{b64}",
        }


def load_previous_iteration(workspace: Path) -> dict[str, dict]:
    """Load previous iteration's feedback and outputs.

    Returns a map of run_id -> {"feedback": str, "outputs": list[dict]}.
    """
    result: dict[str, dict] = {}

    # Load feedback
    feedback_map: dict[str, str] = {}
    feedback_path = workspace / "feedback.json"
    if feedback_path.exists():
        try:
            data = json.loads(feedback_path.read_text())
            feedback_map = {
                r["run_id"]: r["feedback"]
                for r in data.get("reviews", [])
                if r.get("feedback", "").strip()
            }
        except (json.JSONDecodeError, OSError, KeyError):
            pass

    # Load runs (to get outputs)
    prev_runs = find_runs(workspace)
    for run in prev_runs:
        result[run["id"]] = {
            "feedback": feedback_map.get(run["id"], ""),
            "outputs": run.get("outputs", []),
        }

    # Also add feedback for run_ids that had feedback but no matching run
    for run_id, fb in feedback_map.items():
        if run_id not in result:
            result[run_id] = {"feedback": fb, "outputs": []}

    return result


def generate_html(
    runs: list[dict],
    skill_name: str,
    previous: dict[str, dict] | None = None,
    benchmark: dict | None = None,
) -> str:
    """Generate the complete standalone HTML page with embedded data."""
    template_path = Path(__file__).parent / "viewer.html"
    template = template_path.read_text()

    # Build previous_feedback and previous_outputs maps for the template
    previous_feedback: dict[str, str] = {}
    previous_outputs: dict[str, list[dict]] = {}
    if previous:
        for run_id, data in previous.items():
            if data.get("feedback"):
                previous_feedback[run_id] = data["feedback"]
            if data.get("outputs"):
                previous_outputs[run_id] = data["outputs"]

    embedded = {
        "skill_name": skill_name,
        "runs": runs,
        "previous_feedback": previous_feedback,
        "previous_outputs": previous_outputs,
    }
    if benchmark:
        embedded["benchmark"] = benchmark

    data_json = json.dumps(embedded)

    return template.replace("/*__EMBEDDED_DATA__*/", f"const EMBEDDED_DATA = {data_json};")


# ---------------------------------------------------------------------------
# HTTP server (stdlib only, zero dependencies)
# ---------------------------------------------------------------------------

def _kill_port(port: int) -> None:
    """Kill any process listening on the given port."""
    try:
        result = subprocess.run(
            ["lsof", "-ti", f":{port}"],
            capture_output=True, text=True, timeout=5,
        )
        for pid_str in result.stdout.strip().split("\n"):
            if pid_str.strip():
                try:
                    os.kill(int(pid_str.strip()), signal.SIGTERM)
                except (ProcessLookupError, ValueError):
                    pass
        if result.stdout.strip():
            time.sleep(0.5)
    except subprocess.TimeoutExpired:
        pass
    except FileNotFoundError:
        print("Note: lsof not found, cannot check if port is in use", file=sys.stderr)

class ReviewHandler(BaseHTTPRequestHandler):
    """Serves the review HTML and handles feedback saves.

    Regenerates the HTML on each page load so that refreshing the browser
    picks up new eval outputs without restarting the server.
    """

    def __init__(
        self,
        workspace: Path,
        skill_name: str,
        feedback_path: Path,
        previous: dict[str, dict],
        benchmark_path: Path | None,
        *args,
        **kwargs,
    ):
        self.workspace = workspace
        self.skill_name = skill_name
        self.feedback_path = feedback_path
        self.previous = previous
        self.benchmark_path = benchmark_path
        super().__init__(*args, **kwargs)

    def do_GET(self) -> None:
        if self.path == "/" or self.path == "/index.html":
            # Regenerate HTML on each request (re-scans workspace for new outputs)
            runs = find_runs(self.workspace)
            benchmark = None
            if self.benchmark_path and self.benchmark_path.exists():
                try:
                    benchmark = json.loads(self.benchmark_path.read_text())
                except (json.JSONDecodeError, OSError):
                    pass
            html = generate_html(runs, self.skill_name, self.previous, benchmark)
            content = html.encode("utf-8")
            self.send_response(200)
            self.send_header("Content-Type", "text/html; charset=utf-8")
            self.send_header("Content-Length", str(len(content)))
            self.end_headers()
            self.wfile.write(content)
        elif self.path == "/api/feedback":
            data = b"{}"
            if self.feedback_path.exists():
                data = self.feedback_path.read_bytes()
            self.send_response(200)
            self.send_header("Content-Type", "application/json")
            self.send_header("Content-Length", str(len(data)))
            self.end_headers()
            self.wfile.write(data)
        else:
            self.send_error(404)

    def do_POST(self) -> None:
        if self.path == "/api/feedback":
            length = int(self.headers.get("Content-Length", 0))
            body = self.rfile.read(length)
            try:
                data = json.loads(body)
                if not isinstance(data, dict) or "reviews" not in data:
                    raise ValueError("Expected JSON object with 'reviews' key")
                self.feedback_path.write_text(json.dumps(data, indent=2) + "\n")
                resp = b'{"ok":true}'
                self.send_response(200)
            except (json.JSONDecodeError, OSError, ValueError) as e:
                resp = json.dumps({"error": str(e)}).encode()
                self.send_response(500)
            self.send_header("Content-Type", "application/json")
            self.send_header("Content-Length", str(len(resp)))
            self.end_headers()
            self.wfile.write(resp)
        else:
            self.send_error(404)

    def log_message(self, format: str, *args: object) -> None:
        # Suppress request logging to keep terminal clean
        pass


def main() -> None:
    parser = argparse.ArgumentParser(description="Generate and serve eval review")
    parser.add_argument("workspace", type=Path, help="Path to workspace directory")
    parser.add_argument("--port", "-p", type=int, default=3117, help="Server port (default: 3117)")
    parser.add_argument("--skill-name", "-n", type=str, default=None, help="Skill name for header")
    parser.add_argument(
        "--previous-workspace", type=Path, default=None,
        help="Path to previous iteration's workspace (shows old outputs and feedback as context)",
    )
    parser.add_argument(
        "--benchmark", type=Path, default=None,
        help="Path to benchmark.json to show in the Benchmark tab",
    )
    parser.add_argument(
        "--static", "-s", type=Path, default=None,
        help="Write standalone HTML to this path instead of starting a server",
    )
    args = parser.parse_args()

    workspace = args.workspace.resolve()
    if not workspace.is_dir():
        print(f"Error: {workspace} is not a directory", file=sys.stderr)
        sys.exit(1)

    runs = find_runs(workspace)
    if not runs:
        print(f"No runs found in {workspace}", file=sys.stderr)
        sys.exit(1)

    skill_name = args.skill_name or workspace.name.replace("-workspace", "")
    feedback_path = workspace / "feedback.json"

    previous: dict[str, dict] = {}
    if args.previous_workspace:
        previous = load_previous_iteration(args.previous_workspace.resolve())

    benchmark_path = args.benchmark.resolve() if args.benchmark else None
    benchmark = None
    if benchmark_path and benchmark_path.exists():
        try:
            benchmark = json.loads(benchmark_path.read_text())
        except (json.JSONDecodeError, OSError):
            pass

    if args.static:
        html = generate_html(runs, skill_name, previous, benchmark)
        args.static.parent.mkdir(parents=True, exist_ok=True)
        args.static.write_text(html)
        print(f"\n  Static viewer written to: {args.static}\n")
        sys.exit(0)

    # Kill any existing process on the target port
    port = args.port
    _kill_port(port)
    handler = partial(ReviewHandler, workspace, skill_name, feedback_path, previous, benchmark_path)
    try:
        server = HTTPServer(("127.0.0.1", port), handler)
    except OSError:
        # Port still in use after kill attempt — find a free one
        server = HTTPServer(("127.0.0.1", 0), handler)
        port = server.server_address[1]

    url = f"http://localhost:{port}"
    print(f"\n  Eval Viewer")
    print(f"  ─────────────────────────────────")
    print(f"  URL:       {url}")
    print(f"  Workspace: {workspace}")
    print(f"  Feedback:  {feedback_path}")
    if previous:
        print(f"  Previous:  {args.previous_workspace} ({len(previous)} runs)")
    if benchmark_path:
        print(f"  Benchmark: {benchmark_path}")
    print(f"\n  Press Ctrl+C to stop.\n")

    webbrowser.open(url)

    try:
        server.serve_forever()
    except KeyboardInterrupt:
        print("\nStopped.")
        server.server_close()


if __name__ == "__main__":
    main()

FILE:eval-viewer/viewer.html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Eval Review</title>
  <link rel="preconnect" href="https://fonts.googleapis.com">
  <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
  <link href="https://fonts.googleapis.com/css2?family=Poppins:wght@500;600&family=Lora:wght@400;500&display=swap" rel="stylesheet">
  <script src="https://cdn.sheetjs.com/xlsx-0.20.3/package/dist/xlsx.full.min.js" integrity="sha384-EnyY0/GSHQGSxSgMwaIPzSESbqoOLSexfnSMN2AP+39Ckmn92stwABZynq1JyzdT" crossorigin="anonymous"></script>
  <style>
    :root {
      --bg: #faf9f5;
      --surface: #ffffff;
      --border: #e8e6dc;
      --text: #141413;
      --text-muted: #b0aea5;
      --accent: #d97757;
      --accent-hover: #c4613f;
      --green: #788c5d;
      --green-bg: #eef2e8;
      --red: #c44;
      --red-bg: #fceaea;
      --header-bg: #141413;
      --header-text: #faf9f5;
      --radius: 6px;
    }

    * { box-sizing: border-box; margin: 0; padding: 0; }

    body {
      font-family: 'Lora', Georgia, serif;
      background: var(--bg);
      color: var(--text);
      height: 100vh;
      display: flex;
      flex-direction: column;
    }

    /* ---- Header ---- */
    .header {
      background: var(--header-bg);
      color: var(--header-text);
      padding: 1rem 2rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-shrink: 0;
    }
    .header h1 {
      font-family: 'Poppins', sans-serif;
      font-size: 1.25rem;
      font-weight: 600;
    }
    .header .instructions {
      font-size: 0.8rem;
      opacity: 0.7;
      margin-top: 0.25rem;
    }
    .header .progress {
      font-size: 0.875rem;
      opacity: 0.8;
      text-align: right;
    }

    /* ---- Main content ---- */
    .main {
      flex: 1;
      overflow-y: auto;
      padding: 1.5rem 2rem;
      display: flex;
      flex-direction: column;
      gap: 1.25rem;
    }

    /* ---- Sections ---- */
    .section {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      flex-shrink: 0;
    }
    .section-header {
      font-family: 'Poppins', sans-serif;
      padding: 0.75rem 1rem;
      font-size: 0.75rem;
      font-weight: 500;
      text-transform: uppercase;
      letter-spacing: 0.05em;
      color: var(--text-muted);
      border-bottom: 1px solid var(--border);
      background: var(--bg);
    }
    .section-body {
      padding: 1rem;
    }

    /* ---- Config badge ---- */
    .config-badge {
      display: inline-block;
      padding: 0.2rem 0.625rem;
      border-radius: 9999px;
      font-family: 'Poppins', sans-serif;
      font-size: 0.6875rem;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.03em;
      margin-left: 0.75rem;
      vertical-align: middle;
    }
    .config-badge.config-primary {
      background: rgba(33, 150, 243, 0.12);
      color: #1976d2;
    }
    .config-badge.config-baseline {
      background: rgba(255, 193, 7, 0.15);
      color: #f57f17;
    }

    /* ---- Prompt ---- */
    .prompt-text {
      white-space: pre-wrap;
      font-size: 0.9375rem;
      line-height: 1.6;
    }

    /* ---- Outputs ---- */
    .output-file {
      border: 1px solid var(--border);
      border-radius: var(--radius);
      overflow: hidden;
    }
    .output-file + .output-file {
      margin-top: 1rem;
    }
    .output-file-header {
      padding: 0.5rem 0.75rem;
      font-size: 0.8rem;
      font-weight: 600;
      color: var(--text-muted);
      background: var(--bg);
      border-bottom: 1px solid var(--border);
      font-family: 'SF Mono', SFMono-Regular, Consolas, 'Liberation Mono', Menlo, monospace;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .output-file-header .dl-btn {
      font-size: 0.7rem;
      color: var(--accent);
      text-decoration: none;
      cursor: pointer;
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
      font-weight: 500;
      opacity: 0.8;
    }
    .output-file-header .dl-btn:hover {
      opacity: 1;
      text-decoration: underline;
    }
    .output-file-content {
      padding: 0.75rem;
      overflow-x: auto;
    }
    .output-file-content pre {
      font-size: 0.8125rem;
      line-height: 1.5;
      white-space: pre-wrap;
      word-break: break-word;
      font-family: 'SF Mono', SFMono-Regular, Consolas, 'Liberation Mono', Menlo, monospace;
    }
    .output-file-content img {
      max-width: 100%;
      height: auto;
      border-radius: 4px;
    }
    .output-file-content iframe {
      width: 100%;
      height: 600px;
      border: none;
    }
    .output-file-content table {
      border-collapse: collapse;
      font-size: 0.8125rem;
      width: 100%;
    }
    .output-file-content table td,
    .output-file-content table th {
      border: 1px solid var(--border);
      padding: 0.375rem 0.5rem;
      text-align: left;
    }
    .output-file-content table th {
      background: var(--bg);
      font-weight: 600;
    }
    .output-file-content .download-link {
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
      padding: 0.5rem 1rem;
      background: var(--bg);
      border: 1px solid var(--border);
      border-radius: 4px;
      color: var(--accent);
      text-decoration: none;
      font-size: 0.875rem;
      cursor: pointer;
    }
    .output-file-content .download-link:hover {
      background: var(--border);
    }
    .empty-state {
      color: var(--text-muted);
      font-style: italic;
      padding: 2rem;
      text-align: center;
    }

    /* ---- Feedback ---- */
    .prev-feedback {
      background: var(--bg);
      border: 1px solid var(--border);
      border-radius: 4px;
      padding: 0.625rem 0.75rem;
      margin-top: 0.75rem;
      font-size: 0.8125rem;
      color: var(--text-muted);
      line-height: 1.5;
    }
    .prev-feedback-label {
      font-size: 0.7rem;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.04em;
      margin-bottom: 0.25rem;
      color: var(--text-muted);
    }
    .feedback-textarea {
      width: 100%;
      min-height: 100px;
      padding: 0.75rem;
      border: 1px solid var(--border);
      border-radius: 4px;
      font-family: inherit;
      font-size: 0.9375rem;
      line-height: 1.5;
      resize: vertical;
      color: var(--text);
    }
    .feedback-textarea:focus {
      outline: none;
      border-color: var(--accent);
      box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
    }
    .feedback-status {
      font-size: 0.75rem;
      color: var(--text-muted);
      margin-top: 0.5rem;
      min-height: 1.1em;
    }

    /* ---- Grades (collapsible) ---- */
    .grades-toggle {
      display: flex;
      align-items: center;
      cursor: pointer;
      user-select: none;
    }
    .grades-toggle:hover {
      color: var(--accent);
    }
    .grades-toggle .arrow {
      margin-right: 0.5rem;
      transition: transform 0.15s;
      font-size: 0.75rem;
    }
    .grades-toggle .arrow.open {
      transform: rotate(90deg);
    }
    .grades-content {
      display: none;
      margin-top: 0.75rem;
    }
    .grades-content.open {
      display: block;
    }
    .grades-summary {
      font-size: 0.875rem;
      margin-bottom: 0.75rem;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }
    .grade-badge {
      display: inline-block;
      padding: 0.125rem 0.5rem;
      border-radius: 9999px;
      font-size: 0.75rem;
      font-weight: 600;
    }
    .grade-pass { background: var(--green-bg); color: var(--green); }
    .grade-fail { background: var(--red-bg); color: var(--red); }
    .assertion-list {
      list-style: none;
    }
    .assertion-item {
      padding: 0.625rem 0;
      border-bottom: 1px solid var(--border);
      font-size: 0.8125rem;
    }
    .assertion-item:last-child { border-bottom: none; }
    .assertion-status {
      font-weight: 600;
      margin-right: 0.5rem;
    }
    .assertion-status.pass { color: var(--green); }
    .assertion-status.fail { color: var(--red); }
    .assertion-evidence {
      color: var(--text-muted);
      font-size: 0.75rem;
      margin-top: 0.25rem;
      padding-left: 1.5rem;
    }

    /* ---- View tabs ---- */
    .view-tabs {
      display: flex;
      gap: 0;
      padding: 0 2rem;
      background: var(--bg);
      border-bottom: 1px solid var(--border);
      flex-shrink: 0;
    }
    .view-tab {
      font-family: 'Poppins', sans-serif;
      padding: 0.625rem 1.25rem;
      font-size: 0.8125rem;
      font-weight: 500;
      cursor: pointer;
      border: none;
      background: none;
      color: var(--text-muted);
      border-bottom: 2px solid transparent;
      transition: all 0.15s;
    }
    .view-tab:hover { color: var(--text); }
    .view-tab.active {
      color: var(--accent);
      border-bottom-color: var(--accent);
    }
    .view-panel { display: none; }
    .view-panel.active { display: flex; flex-direction: column; flex: 1; overflow: hidden; }

    /* ---- Benchmark view ---- */
    .benchmark-view {
      padding: 1.5rem 2rem;
      overflow-y: auto;
      flex: 1;
    }
    .benchmark-table {
      border-collapse: collapse;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      font-size: 0.8125rem;
      width: 100%;
      margin-bottom: 1.5rem;
    }
    .benchmark-table th, .benchmark-table td {
      padding: 0.625rem 0.75rem;
      text-align: left;
      border: 1px solid var(--border);
    }
    .benchmark-table th {
      font-family: 'Poppins', sans-serif;
      background: var(--header-bg);
      color: var(--header-text);
      font-weight: 500;
      font-size: 0.75rem;
      text-transform: uppercase;
      letter-spacing: 0.04em;
    }
    .benchmark-table tr:hover { background: var(--bg); }
    .benchmark-table tr.benchmark-row-with { background: rgba(33, 150, 243, 0.06); }
    .benchmark-table tr.benchmark-row-without { background: rgba(255, 193, 7, 0.06); }
    .benchmark-table tr.benchmark-row-with:hover { background: rgba(33, 150, 243, 0.12); }
    .benchmark-table tr.benchmark-row-without:hover { background: rgba(255, 193, 7, 0.12); }
    .benchmark-table tr.benchmark-row-avg { font-weight: 600; border-top: 2px solid var(--border); }
    .benchmark-table tr.benchmark-row-avg.benchmark-row-with { background: rgba(33, 150, 243, 0.12); }
    .benchmark-table tr.benchmark-row-avg.benchmark-row-without { background: rgba(255, 193, 7, 0.12); }
    .benchmark-delta-positive { color: var(--green); font-weight: 600; }
    .benchmark-delta-negative { color: var(--red); font-weight: 600; }
    .benchmark-notes {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      padding: 1rem;
    }
    .benchmark-notes h3 {
      font-family: 'Poppins', sans-serif;
      font-size: 0.875rem;
      margin-bottom: 0.75rem;
    }
    .benchmark-notes ul {
      list-style: disc;
      padding-left: 1.25rem;
    }
    .benchmark-notes li {
      font-size: 0.8125rem;
      line-height: 1.6;
      margin-bottom: 0.375rem;
    }
    .benchmark-empty {
      color: var(--text-muted);
      font-style: italic;
      text-align: center;
      padding: 3rem;
    }

    /* ---- Navigation ---- */
    .nav {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 1rem 2rem;
      border-top: 1px solid var(--border);
      background: var(--surface);
      flex-shrink: 0;
    }
    .nav-btn {
      font-family: 'Poppins', sans-serif;
      padding: 0.5rem 1.25rem;
      border: 1px solid var(--border);
      border-radius: var(--radius);
      background: var(--surface);
      cursor: pointer;
      font-size: 0.875rem;
      font-weight: 500;
      color: var(--text);
      transition: all 0.15s;
    }
    .nav-btn:hover:not(:disabled) {
      background: var(--bg);
      border-color: var(--text-muted);
    }
    .nav-btn:disabled {
      opacity: 0.4;
      cursor: not-allowed;
    }
    .done-btn {
      font-family: 'Poppins', sans-serif;
      padding: 0.5rem 1.5rem;
      border: 1px solid var(--border);
      border-radius: var(--radius);
      background: var(--surface);
      color: var(--text);
      cursor: pointer;
      font-size: 0.875rem;
      font-weight: 500;
      transition: all 0.15s;
    }
    .done-btn:hover {
      background: var(--bg);
      border-color: var(--text-muted);
    }
    .done-btn.ready {
      border: none;
      background: var(--accent);
      color: white;
      font-weight: 600;
    }
    .done-btn.ready:hover {
      background: var(--accent-hover);
    }
    /* ---- Done overlay ---- */
    .done-overlay {
      display: none;
      position: fixed;
      inset: 0;
      background: rgba(0, 0, 0, 0.5);
      z-index: 100;
      justify-content: center;
      align-items: center;
    }
    .done-overlay.visible {
      display: flex;
    }
    .done-card {
      background: var(--surface);
      border-radius: 12px;
      padding: 2rem 3rem;
      text-align: center;
      box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
      max-width: 500px;
    }
    .done-card h2 {
      font-size: 1.5rem;
      margin-bottom: 0.5rem;
    }
    .done-card p {
      color: var(--text-muted);
      margin-bottom: 1.5rem;
      line-height: 1.5;
    }
    .done-card .btn-row {
      display: flex;
      gap: 0.5rem;
      justify-content: center;
    }
    .done-card button {
      padding: 0.5rem 1.25rem;
      border: 1px solid var(--border);
      border-radius: var(--radius);
      background: var(--surface);
      cursor: pointer;
      font-size: 0.875rem;
    }
    .done-card button:hover {
      background: var(--bg);
    }
    /* ---- Toast ---- */
    .toast {
      position: fixed;
      bottom: 5rem;
      left: 50%;
      transform: translateX(-50%);
      background: var(--header-bg);
      color: var(--header-text);
      padding: 0.625rem 1.25rem;
      border-radius: var(--radius);
      font-size: 0.875rem;
      opacity: 0;
      transition: opacity 0.3s;
      pointer-events: none;
      z-index: 200;
    }
    .toast.visible {
      opacity: 1;
    }
  </style>
</head>
<body>
  <div id="app" style="height:100vh; display:flex; flex-direction:column;">
    <div class="header">
      <div>
        <h1>Eval Review: <span id="skill-name"></span></h1>
        <div class="instructions">Review each output and leave feedback below. Navigate with arrow keys or buttons. When done, copy feedback and paste into Claude Code.</div>
      </div>
      <div class="progress" id="progress"></div>
    </div>

    <!-- View tabs (only shown when benchmark data exists) -->
    <div class="view-tabs" id="view-tabs" style="display:none;">
      <button class="view-tab active" onclick="switchView('outputs')">Outputs</button>
      <button class="view-tab" onclick="switchView('benchmark')">Benchmark</button>
    </div>

    <!-- Outputs panel (qualitative review) -->
    <div class="view-panel active" id="panel-outputs">
    <div class="main">
      <!-- Prompt -->
      <div class="section">
        <div class="section-header">Prompt <span class="config-badge" id="config-badge" style="display:none;"></span></div>
        <div class="section-body">
          <div class="prompt-text" id="prompt-text"></div>
        </div>
      </div>

      <!-- Outputs -->
      <div class="section">
        <div class="section-header">Output</div>
        <div class="section-body" id="outputs-body">
          <div class="empty-state">No output files found</div>
        </div>
      </div>

      <!-- Previous Output (collapsible) -->
      <div class="section" id="prev-outputs-section" style="display:none;">
        <div class="section-header">
          <div class="grades-toggle" onclick="togglePrevOutputs()">
            <span class="arrow" id="prev-outputs-arrow">&#9654;</span>
            Previous Output
          </div>
        </div>
        <div class="grades-content" id="prev-outputs-content"></div>
      </div>

      <!-- Grades (collapsible) -->
      <div class="section" id="grades-section" style="display:none;">
        <div class="section-header">
          <div class="grades-toggle" onclick="toggleGrades()">
            <span class="arrow" id="grades-arrow">&#9654;</span>
            Formal Grades
          </div>
        </div>
        <div class="grades-content" id="grades-content"></div>
      </div>

      <!-- Feedback -->
      <div class="section">
        <div class="section-header">Your Feedback</div>
        <div class="section-body">
          <textarea
            class="feedback-textarea"
            id="feedback"
            placeholder="What do you think of this output? Any issues, suggestions, or things that look great?"
          ></textarea>
          <div class="feedback-status" id="feedback-status"></div>
          <div class="prev-feedback" id="prev-feedback" style="display:none;">
            <div class="prev-feedback-label">Previous feedback</div>
            <div id="prev-feedback-text"></div>
          </div>
        </div>
      </div>
    </div>

    <div class="nav" id="outputs-nav">
      <button class="nav-btn" id="prev-btn" onclick="navigate(-1)">&#8592; Previous</button>
      <button class="done-btn" id="done-btn" onclick="showDoneDialog()">Submit All Reviews</button>
      <button class="nav-btn" id="next-btn" onclick="navigate(1)">Next &#8594;</button>
    </div>
    </div><!-- end panel-outputs -->

    <!-- Benchmark panel (quantitative stats) -->
    <div class="view-panel" id="panel-benchmark">
      <div class="benchmark-view" id="benchmark-content">
        <div class="benchmark-empty">No benchmark data available. Run a benchmark to see quantitative results here.</div>
      </div>
    </div>
  </div>

  <!-- Done overlay -->
  <div class="done-overlay" id="done-overlay">
    <div class="done-card">
      <h2>Review Complete</h2>
      <p>Your feedback has been saved. Go back to your Claude Code session and tell Claude you're done reviewing.</p>
      <div class="btn-row">
        <button onclick="closeDoneDialog()">OK</button>
      </div>
    </div>
  </div>

  <!-- Toast -->
  <div class="toast" id="toast"></div>

  <script>
    // ---- Embedded data (injected by generate_review.py) ----
    /*__EMBEDDED_DATA__*/

    // ---- State ----
    let feedbackMap = {};  // run_id -> feedback text
    let currentIndex = 0;
    let visitedRuns = new Set();

    // ---- Init ----
    async function init() {
      // Load saved feedback from server — but only if this isn't a fresh
      // iteration (indicated by previous_feedback being present). When
      // previous feedback exists, the feedback.json on disk is stale from
      // the prior iteration and should not pre-fill the textareas.
      const hasPrevious = Object.keys(EMBEDDED_DATA.previous_feedback || {}).length > 0
        || Object.keys(EMBEDDED_DATA.previous_outputs || {}).length > 0;
      if (!hasPrevious) {
        try {
          const resp = await fetch("/api/feedback");
          const data = await resp.json();
          if (data.reviews) {
            for (const r of data.reviews) feedbackMap[r.run_id] = r.feedback;
          }
        } catch { /* first run, no feedback yet */ }
      }

      document.getElementById("skill-name").textContent = EMBEDDED_DATA.skill_name;
      showRun(0);

      // Wire up feedback auto-save
      const textarea = document.getElementById("feedback");
      let saveTimeout = null;
      textarea.addEventListener("input", () => {
        clearTimeout(saveTimeout);
        document.getElementById("feedback-status").textContent = "";
        saveTimeout = setTimeout(() => saveCurrentFeedback(), 800);
      });
    }

    // ---- Navigation ----
    function navigate(delta) {
      const newIndex = currentIndex + delta;
      if (newIndex >= 0 && newIndex < EMBEDDED_DATA.runs.length) {
        saveCurrentFeedback();
        showRun(newIndex);
      }
    }

    function updateNavButtons() {
      document.getElementById("prev-btn").disabled = currentIndex === 0;
      document.getElementById("next-btn").disabled =
        currentIndex === EMBEDDED_DATA.runs.length - 1;
    }

    // ---- Show a run ----
    function showRun(index) {
      currentIndex = index;
      const run = EMBEDDED_DATA.runs[index];

      // Progress
      document.getElementById("progress").textContent =
        `index + 1 of EMBEDDED_DATA.runs.length`;

      // Prompt
      document.getElementById("prompt-text").textContent = run.prompt;

      // Config badge
      const badge = document.getElementById("config-badge");
      const configMatch = run.id.match(/(with_skill|without_skill|new_skill|old_skill)/);
      if (configMatch) {
        const config = configMatch[1];
        const isBaseline = config === "without_skill" || config === "old_skill";
        badge.textContent = config.replace(/_/g, " ");
        badge.className = "config-badge " + (isBaseline ? "config-baseline" : "config-primary");
        badge.style.display = "inline-block";
      } else {
        badge.style.display = "none";
      }

      // Outputs
      renderOutputs(run);

      // Previous outputs
      renderPrevOutputs(run);

      // Grades
      renderGrades(run);

      // Previous feedback
      const prevFb = (EMBEDDED_DATA.previous_feedback || {})[run.id];
      const prevEl = document.getElementById("prev-feedback");
      if (prevFb) {
        document.getElementById("prev-feedback-text").textContent = prevFb;
        prevEl.style.display = "block";
      } else {
        prevEl.style.display = "none";
      }

      // Feedback
      document.getElementById("feedback").value = feedbackMap[run.id] || "";
      document.getElementById("feedback-status").textContent = "";

      updateNavButtons();

      // Track visited runs and promote done button when all visited
      visitedRuns.add(index);
      const doneBtn = document.getElementById("done-btn");
      if (visitedRuns.size >= EMBEDDED_DATA.runs.length) {
        doneBtn.classList.add("ready");
      }

      // Scroll main content to top
      document.querySelector(".main").scrollTop = 0;
    }

    // ---- Render outputs ----
    function renderOutputs(run) {
      const container = document.getElementById("outputs-body");
      container.innerHTML = "";

      const outputs = run.outputs || [];
      if (outputs.length === 0) {
        container.innerHTML = '<div class="empty-state">No output files</div>';
        return;
      }

      for (const file of outputs) {
        const fileDiv = document.createElement("div");
        fileDiv.className = "output-file";

        // Always show file header with download link
        const header = document.createElement("div");
        header.className = "output-file-header";
        const nameSpan = document.createElement("span");
        nameSpan.textContent = file.name;
        header.appendChild(nameSpan);
        const dlBtn = document.createElement("a");
        dlBtn.className = "dl-btn";
        dlBtn.textContent = "Download";
        dlBtn.download = file.name;
        dlBtn.href = getDownloadUri(file);
        header.appendChild(dlBtn);
        fileDiv.appendChild(header);

        const content = document.createElement("div");
        content.className = "output-file-content";

        if (file.type === "text") {
          const pre = document.createElement("pre");
          pre.textContent = file.content;
          content.appendChild(pre);
        } else if (file.type === "image") {
          const img = document.createElement("img");
          img.src = file.data_uri;
          img.alt = file.name;
          content.appendChild(img);
        } else if (file.type === "pdf") {
          const iframe = document.createElement("iframe");
          iframe.src = file.data_uri;
          content.appendChild(iframe);
        } else if (file.type === "xlsx") {
          renderXlsx(content, file.data_b64);
        } else if (file.type === "binary") {
          const a = document.createElement("a");
          a.className = "download-link";
          a.href = file.data_uri;
          a.download = file.name;
          a.textContent = "Download " + file.name;
          content.appendChild(a);
        } else if (file.type === "error") {
          const pre = document.createElement("pre");
          pre.textContent = file.content;
          pre.style.color = "var(--red)";
          content.appendChild(pre);
        }

        fileDiv.appendChild(content);
        container.appendChild(fileDiv);
      }
    }

    // ---- XLSX rendering via SheetJS ----
    function renderXlsx(container, b64Data) {
      try {
        const raw = Uint8Array.from(atob(b64Data), c => c.charCodeAt(0));
        const wb = XLSX.read(raw, { type: "array" });

        for (let i = 0; i < wb.SheetNames.length; i++) {
          const sheetName = wb.SheetNames[i];
          const ws = wb.Sheets[sheetName];

          if (wb.SheetNames.length > 1) {
            const sheetLabel = document.createElement("div");
            sheetLabel.style.cssText =
              "font-weight:600; font-size:0.8rem; color:#b0aea5; margin-top:0.5rem; margin-bottom:0.25rem;";
            sheetLabel.textContent = "Sheet: " + sheetName;
            container.appendChild(sheetLabel);
          }

          const htmlStr = XLSX.utils.sheet_to_html(ws, { editable: false });
          const wrapper = document.createElement("div");
          wrapper.innerHTML = htmlStr;
          container.appendChild(wrapper);
        }
      } catch (err) {
        container.textContent = "Error rendering spreadsheet: " + err.message;
      }
    }

    // ---- Grades ----
    function renderGrades(run) {
      const section = document.getElementById("grades-section");
      const content = document.getElementById("grades-content");

      if (!run.grading) {
        section.style.display = "none";
        return;
      }

      const grading = run.grading;
      section.style.display = "block";
      // Reset to collapsed
      content.classList.remove("open");
      document.getElementById("grades-arrow").classList.remove("open");

      const summary = grading.summary || {};
      const expectations = grading.expectations || [];

      let html = '<div style="padding: 1rem;">';

      // Summary line
      const passRate = summary.pass_rate != null
        ? Math.round(summary.pass_rate * 100) + "%"
        : "?";
      const badgeClass = summary.pass_rate >= 0.8 ? "grade-pass" : summary.pass_rate >= 0.5 ? "" : "grade-fail";
      html += '<div class="grades-summary">';
      html += '<span class="grade-badge ' + badgeClass + '">' + passRate + '</span>';
      html += '<span>' + (summary.passed || 0) + ' passed, ' + (summary.failed || 0) + ' failed of ' + (summary.total || 0) + '</span>';
      html += '</div>';

      // Assertions list
      html += '<ul class="assertion-list">';
      for (const exp of expectations) {
        const statusClass = exp.passed ? "pass" : "fail";
        const statusIcon = exp.passed ? "\u2713" : "\u2717";
        html += '<li class="assertion-item">';
        html += '<span class="assertion-status ' + statusClass + '">' + statusIcon + '</span>';
        html += '<span>' + escapeHtml(exp.text) + '</span>';
        if (exp.evidence) {
          html += '<div class="assertion-evidence">' + escapeHtml(exp.evidence) + '</div>';
        }
        html += '</li>';
      }
      html += '</ul>';

      html += '</div>';
      content.innerHTML = html;
    }

    function toggleGrades() {
      const content = document.getElementById("grades-content");
      const arrow = document.getElementById("grades-arrow");
      content.classList.toggle("open");
      arrow.classList.toggle("open");
    }

    // ---- Previous outputs (collapsible) ----
    function renderPrevOutputs(run) {
      const section = document.getElementById("prev-outputs-section");
      const content = document.getElementById("prev-outputs-content");
      const prevOutputs = (EMBEDDED_DATA.previous_outputs || {})[run.id];

      if (!prevOutputs || prevOutputs.length === 0) {
        section.style.display = "none";
        return;
      }

      section.style.display = "block";
      // Reset to collapsed
      content.classList.remove("open");
      document.getElementById("prev-outputs-arrow").classList.remove("open");

      // Render the files into the content area
      content.innerHTML = "";
      const wrapper = document.createElement("div");
      wrapper.style.padding = "1rem";

      for (const file of prevOutputs) {
        const fileDiv = document.createElement("div");
        fileDiv.className = "output-file";

        const header = document.createElement("div");
        header.className = "output-file-header";
        const nameSpan = document.createElement("span");
        nameSpan.textContent = file.name;
        header.appendChild(nameSpan);
        const dlBtn = document.createElement("a");
        dlBtn.className = "dl-btn";
        dlBtn.textContent = "Download";
        dlBtn.download = file.name;
        dlBtn.href = getDownloadUri(file);
        header.appendChild(dlBtn);
        fileDiv.appendChild(header);

        const fc = document.createElement("div");
        fc.className = "output-file-content";

        if (file.type === "text") {
          const pre = document.createElement("pre");
          pre.textContent = file.content;
          fc.appendChild(pre);
        } else if (file.type === "image") {
          const img = document.createElement("img");
          img.src = file.data_uri;
          img.alt = file.name;
          fc.appendChild(img);
        } else if (file.type === "pdf") {
          const iframe = document.createElement("iframe");
          iframe.src = file.data_uri;
          fc.appendChild(iframe);
        } else if (file.type === "xlsx") {
          renderXlsx(fc, file.data_b64);
        } else if (file.type === "binary") {
          const a = document.createElement("a");
          a.className = "download-link";
          a.href = file.data_uri;
          a.download = file.name;
          a.textContent = "Download " + file.name;
          fc.appendChild(a);
        }

        fileDiv.appendChild(fc);
        wrapper.appendChild(fileDiv);
      }

      content.appendChild(wrapper);
    }

    function togglePrevOutputs() {
      const content = document.getElementById("prev-outputs-content");
      const arrow = document.getElementById("prev-outputs-arrow");
      content.classList.toggle("open");
      arrow.classList.toggle("open");
    }

    // ---- Feedback (saved to server -> feedback.json) ----
    function saveCurrentFeedback() {
      const run = EMBEDDED_DATA.runs[currentIndex];
      const text = document.getElementById("feedback").value;

      if (text.trim() === "") {
        delete feedbackMap[run.id];
      } else {
        feedbackMap[run.id] = text;
      }

      // Build reviews array from map
      const reviews = [];
      for (const [run_id, feedback] of Object.entries(feedbackMap)) {
        if (feedback.trim()) {
          reviews.push({ run_id, feedback, timestamp: new Date().toISOString() });
        }
      }

      fetch("/api/feedback", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ reviews, status: "in_progress" }),
      }).then(() => {
        document.getElementById("feedback-status").textContent = "Saved";
      }).catch(() => {
        // Static mode or server unavailable — no-op on auto-save,
        // feedback will be downloaded on final submit
        document.getElementById("feedback-status").textContent = "Will download on submit";
      });
    }

    // ---- Done ----
    function showDoneDialog() {
      // Save current textarea to feedbackMap (but don't POST yet)
      const run = EMBEDDED_DATA.runs[currentIndex];
      const text = document.getElementById("feedback").value;
      if (text.trim() === "") {
        delete feedbackMap[run.id];
      } else {
        feedbackMap[run.id] = text;
      }

      // POST once with status: complete — include ALL runs so the model
      // can distinguish "no feedback" (looks good) from "not reviewed"
      const reviews = [];
      const ts = new Date().toISOString();
      for (const r of EMBEDDED_DATA.runs) {
        reviews.push({ run_id: r.id, feedback: feedbackMap[r.id] || "", timestamp: ts });
      }
      const payload = JSON.stringify({ reviews, status: "complete" }, null, 2);
      fetch("/api/feedback", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: payload,
      }).then(() => {
        document.getElementById("done-overlay").classList.add("visible");
      }).catch(() => {
        // Server not available (static mode) — download as file
        const blob = new Blob([payload], { type: "application/json" });
        const url = URL.createObjectURL(blob);
        const a = document.createElement("a");
        a.href = url;
        a.download = "feedback.json";
        a.click();
        URL.revokeObjectURL(url);
        document.getElementById("done-overlay").classList.add("visible");
      });
    }

    function closeDoneDialog() {
      // Reset status back to in_progress
      saveCurrentFeedback();
      document.getElementById("done-overlay").classList.remove("visible");
    }

    // ---- Toast ----
    function showToast(message) {
      const toast = document.getElementById("toast");
      toast.textContent = message;
      toast.classList.add("visible");
      setTimeout(() => toast.classList.remove("visible"), 2000);
    }

    // ---- Keyboard nav ----
    document.addEventListener("keydown", (e) => {
      // Don't capture when typing in textarea
      if (e.target.tagName === "TEXTAREA") return;

      if (e.key === "ArrowLeft" || e.key === "ArrowUp") {
        e.preventDefault();
        navigate(-1);
      } else if (e.key === "ArrowRight" || e.key === "ArrowDown") {
        e.preventDefault();
        navigate(1);
      }
    });

    // ---- Util ----
    function getDownloadUri(file) {
      if (file.data_uri) return file.data_uri;
      if (file.data_b64) return "data:application/octet-stream;base64," + file.data_b64;
      if (file.type === "text") return "data:text/plain;charset=utf-8," + encodeURIComponent(file.content);
      return "#";
    }

    function escapeHtml(text) {
      const div = document.createElement("div");
      div.textContent = text;
      return div.innerHTML;
    }

    // ---- View switching ----
    function switchView(view) {
      document.querySelectorAll(".view-tab").forEach(t => t.classList.remove("active"));
      document.querySelectorAll(".view-panel").forEach(p => p.classList.remove("active"));
      document.querySelector(`[onclick="switchView('view')"]`).classList.add("active");
      document.getElementById("panel-" + view).classList.add("active");
    }

    // ---- Benchmark rendering ----
    function renderBenchmark() {
      const data = EMBEDDED_DATA.benchmark;
      if (!data) return;

      // Show the tabs
      document.getElementById("view-tabs").style.display = "flex";

      const container = document.getElementById("benchmark-content");
      const summary = data.run_summary || {};
      const metadata = data.metadata || {};
      const notes = data.notes || [];

      let html = "";

      // Header
      html += "<h2 style='font-family: Poppins, sans-serif; margin-bottom: 0.5rem;'>Benchmark Results</h2>";
      html += "<p style='color: var(--text-muted); font-size: 0.875rem; margin-bottom: 1.25rem;'>";
      if (metadata.skill_name) html += "<strong>" + escapeHtml(metadata.skill_name) + "</strong> &mdash; ";
      if (metadata.timestamp) html += metadata.timestamp + " &mdash; ";
      if (metadata.evals_run) html += "Evals: " + metadata.evals_run.join(", ") + " &mdash; ";
      html += (metadata.runs_per_configuration || "?") + " runs per configuration";
      html += "</p>";

      // Summary table
      html += '<table class="benchmark-table">';

      function fmtStat(stat, pct) {
        if (!stat) return "—";
        const suffix = pct ? "%" : "";
        const m = pct ? (stat.mean * 100).toFixed(0) : stat.mean.toFixed(1);
        const s = pct ? (stat.stddev * 100).toFixed(0) : stat.stddev.toFixed(1);
        return m + suffix + " ± " + s + suffix;
      }

      function deltaClass(val) {
        if (!val) return "";
        const n = parseFloat(val);
        if (n > 0) return "benchmark-delta-positive";
        if (n < 0) return "benchmark-delta-negative";
        return "";
      }

      // Discover config names dynamically (everything except "delta")
      const configs = Object.keys(summary).filter(k => k !== "delta");
      const configA = configs[0] || "config_a";
      const configB = configs[1] || "config_b";
      const labelA = configA.replace(/_/g, " ").replace(/\b\w/g, c => c.toUpperCase());
      const labelB = configB.replace(/_/g, " ").replace(/\b\w/g, c => c.toUpperCase());
      const a = summary[configA] || {};
      const b = summary[configB] || {};
      const delta = summary.delta || {};

      html += "<thead><tr><th>Metric</th><th>" + escapeHtml(labelA) + "</th><th>" + escapeHtml(labelB) + "</th><th>Delta</th></tr></thead>";
      html += "<tbody>";

      html += "<tr><td><strong>Pass Rate</strong></td>";
      html += "<td>" + fmtStat(a.pass_rate, true) + "</td>";
      html += "<td>" + fmtStat(b.pass_rate, true) + "</td>";
      html += '<td class="' + deltaClass(delta.pass_rate) + '">' + (delta.pass_rate || "—") + "</td></tr>";

      // Time (only show row if data exists)
      if (a.time_seconds || b.time_seconds) {
        html += "<tr><td><strong>Time (s)</strong></td>";
        html += "<td>" + fmtStat(a.time_seconds, false) + "</td>";
        html += "<td>" + fmtStat(b.time_seconds, false) + "</td>";
        html += '<td class="' + deltaClass(delta.time_seconds) + '">' + (delta.time_seconds ? delta.time_seconds + "s" : "—") + "</td></tr>";
      }

      // Tokens (only show row if data exists)
      if (a.tokens || b.tokens) {
        html += "<tr><td><strong>Tokens</strong></td>";
        html += "<td>" + fmtStat(a.tokens, false) + "</td>";
        html += "<td>" + fmtStat(b.tokens, false) + "</td>";
        html += '<td class="' + deltaClass(delta.tokens) + '">' + (delta.tokens || "—") + "</td></tr>";
      }

      html += "</tbody></table>";

      // Per-eval breakdown (if runs data available)
      const runs = data.runs || [];
      if (runs.length > 0) {
        const evalIds = [...new Set(runs.map(r => r.eval_id))].sort((a, b) => a - b);

        html += "<h3 style='font-family: Poppins, sans-serif; margin-bottom: 0.75rem;'>Per-Eval Breakdown</h3>";

        const hasTime = runs.some(r => r.result && r.result.time_seconds != null);
        const hasErrors = runs.some(r => r.result && r.result.errors > 0);

        for (const evalId of evalIds) {
          const evalRuns = runs.filter(r => r.eval_id === evalId);
          const evalName = evalRuns[0] && evalRuns[0].eval_name ? evalRuns[0].eval_name : "Eval " + evalId;

          html += "<h4 style='font-family: Poppins, sans-serif; margin: 1rem 0 0.5rem; color: var(--text);'>" + escapeHtml(evalName) + "</h4>";
          html += '<table class="benchmark-table">';
          html += "<thead><tr><th>Config</th><th>Run</th><th>Pass Rate</th>";
          if (hasTime) html += "<th>Time (s)</th>";
          if (hasErrors) html += "<th>Crashes During Execution</th>";
          html += "</tr></thead>";
          html += "<tbody>";

          // Group by config and render with average rows
          const configGroups = [...new Set(evalRuns.map(r => r.configuration))];
          for (let ci = 0; ci < configGroups.length; ci++) {
            const config = configGroups[ci];
            const configRuns = evalRuns.filter(r => r.configuration === config);
            if (configRuns.length === 0) continue;

            const rowClass = ci === 0 ? "benchmark-row-with" : "benchmark-row-without";
            const configLabel = config.replace(/_/g, " ").replace(/\b\w/g, c => c.toUpperCase());

            for (const run of configRuns) {
              const r = run.result || {};
              const prClass = r.pass_rate >= 0.8 ? "benchmark-delta-positive" : r.pass_rate < 0.5 ? "benchmark-delta-negative" : "";
              html += '<tr class="' + rowClass + '">';
              html += "<td>" + configLabel + "</td>";
              html += "<td>" + run.run_number + "</td>";
              html += '<td class="' + prClass + '">' + ((r.pass_rate || 0) * 100).toFixed(0) + "% (" + (r.passed || 0) + "/" + (r.total || 0) + ")</td>";
              if (hasTime) html += "<td>" + (r.time_seconds != null ? r.time_seconds.toFixed(1) : "—") + "</td>";
              if (hasErrors) html += "<td>" + (r.errors || 0) + "</td>";
              html += "</tr>";
            }

            // Average row
            const rates = configRuns.map(r => (r.result || {}).pass_rate || 0);
            const avgRate = rates.reduce((a, b) => a + b, 0) / rates.length;
            const avgPrClass = avgRate >= 0.8 ? "benchmark-delta-positive" : avgRate < 0.5 ? "benchmark-delta-negative" : "";
            html += '<tr class="benchmark-row-avg ' + rowClass + '">';
            html += "<td>" + configLabel + "</td>";
            html += "<td>Avg</td>";
            html += '<td class="' + avgPrClass + '">' + (avgRate * 100).toFixed(0) + "%</td>";
            if (hasTime) {
              const times = configRuns.map(r => (r.result || {}).time_seconds).filter(t => t != null);
              html += "<td>" + (times.length ? (times.reduce((a, b) => a + b, 0) / times.length).toFixed(1) : "—") + "</td>";
            }
            if (hasErrors) html += "<td></td>";
            html += "</tr>";
          }
          html += "</tbody></table>";

          // Per-assertion detail for this eval
          const runsWithExpectations = {};
          for (const config of configGroups) {
            runsWithExpectations[config] = evalRuns.filter(r => r.configuration === config && r.expectations && r.expectations.length > 0);
          }
          const hasAnyExpectations = Object.values(runsWithExpectations).some(runs => runs.length > 0);
          if (hasAnyExpectations) {
            // Collect all unique assertion texts across all configs
            const allAssertions = [];
            const seen = new Set();
            for (const config of configGroups) {
              for (const run of runsWithExpectations[config]) {
                for (const exp of (run.expectations || [])) {
                  if (!seen.has(exp.text)) {
                    seen.add(exp.text);
                    allAssertions.push(exp.text);
                  }
                }
              }
            }

            html += '<table class="benchmark-table" style="margin-top: 0.5rem;">';
            html += "<thead><tr><th>Assertion</th>";
            for (const config of configGroups) {
              const label = config.replace(/_/g, " ").replace(/\b\w/g, c => c.toUpperCase());
              html += "<th>" + escapeHtml(label) + "</th>";
            }
            html += "</tr></thead><tbody>";

            for (const assertionText of allAssertions) {
              html += "<tr><td>" + escapeHtml(assertionText) + "</td>";

              for (const config of configGroups) {
                html += "<td>";
                for (const run of runsWithExpectations[config]) {
                  const exp = (run.expectations || []).find(e => e.text === assertionText);
                  if (exp) {
                    const cls = exp.passed ? "benchmark-delta-positive" : "benchmark-delta-negative";
                    const icon = exp.passed ? "\u2713" : "\u2717";
                    html += '<span class="' + cls + '" title="Run ' + run.run_number + ': ' + escapeHtml(exp.evidence || "") + '">' + icon + "</span> ";
                  } else {
                    html += "— ";
                  }
                }
                html += "</td>";
              }
              html += "</tr>";
            }
            html += "</tbody></table>";
          }
        }
      }

      // Notes
      if (notes.length > 0) {
        html += '<div class="benchmark-notes">';
        html += "<h3>Analysis Notes</h3>";
        html += "<ul>";
        for (const note of notes) {
          html += "<li>" + escapeHtml(note) + "</li>";
        }
        html += "</ul></div>";
      }

      container.innerHTML = html;
    }

    // ---- Start ----
    init();
    renderBenchmark();
  </script>
</body>
</html>

FILE:references/schemas.md
# JSON Schemas

This document defines the JSON schemas used by skill-creator.

---

## evals.json

Defines the evals for a skill. Located at `evals/evals.json` within the skill directory.

```json
{
  "skill_name": "example-skill",
  "evals": [
    {
      "id": 1,
      "prompt": "User's example prompt",
      "expected_output": "Description of expected result",
      "files": ["evals/files/sample1.pdf"],
      "expectations": [
        "The output includes X",
        "The skill used script Y"
      ]
    }
  ]
}
```

**Fields:**
- `skill_name`: Name matching the skill's frontmatter
- `evals[].id`: Unique integer identifier
- `evals[].prompt`: The task to execute
- `evals[].expected_output`: Human-readable description of success
- `evals[].files`: Optional list of input file paths (relative to skill root)
- `evals[].expectations`: List of verifiable statements

---

## history.json

Tracks version progression in Improve mode. Located at workspace root.

```json
{
  "started_at": "2026-01-15T10:30:00Z",
  "skill_name": "pdf",
  "current_best": "v2",
  "iterations": [
    {
      "version": "v0",
      "parent": null,
      "expectation_pass_rate": 0.65,
      "grading_result": "baseline",
      "is_current_best": false
    },
    {
      "version": "v1",
      "parent": "v0",
      "expectation_pass_rate": 0.75,
      "grading_result": "won",
      "is_current_best": false
    },
    {
      "version": "v2",
      "parent": "v1",
      "expectation_pass_rate": 0.85,
      "grading_result": "won",
      "is_current_best": true
    }
  ]
}
```

**Fields:**
- `started_at`: ISO timestamp of when improvement started
- `skill_name`: Name of the skill being improved
- `current_best`: Version identifier of the best performer
- `iterations[].version`: Version identifier (v0, v1, ...)
- `iterations[].parent`: Parent version this was derived from
- `iterations[].expectation_pass_rate`: Pass rate from grading
- `iterations[].grading_result`: "baseline", "won", "lost", or "tie"
- `iterations[].is_current_best`: Whether this is the current best version

---

## grading.json

Output from the grader agent. Located at `<run-dir>/grading.json`.

```json
{
  "expectations": [
    {
      "text": "The output includes the name 'John Smith'",
      "passed": true,
      "evidence": "Found in transcript Step 3: 'Extracted names: John Smith, Sarah Johnson'"
    },
    {
      "text": "The spreadsheet has a SUM formula in cell B10",
      "passed": false,
      "evidence": "No spreadsheet was created. The output was a text file."
    }
  ],
  "summary": {
    "passed": 2,
    "failed": 1,
    "total": 3,
    "pass_rate": 0.67
  },
  "execution_metrics": {
    "tool_calls": {
      "Read": 5,
      "Write": 2,
      "Bash": 8
    },
    "total_tool_calls": 15,
    "total_steps": 6,
    "errors_encountered": 0,
    "output_chars": 12450,
    "transcript_chars": 3200
  },
  "timing": {
    "executor_duration_seconds": 165.0,
    "grader_duration_seconds": 26.0,
    "total_duration_seconds": 191.0
  },
  "claims": [
    {
      "claim": "The form has 12 fillable fields",
      "type": "factual",
      "verified": true,
      "evidence": "Counted 12 fields in field_info.json"
    }
  ],
  "user_notes_summary": {
    "uncertainties": ["Used 2023 data, may be stale"],
    "needs_review": [],
    "workarounds": ["Fell back to text overlay for non-fillable fields"]
  },
  "eval_feedback": {
    "suggestions": [
      {
        "assertion": "The output includes the name 'John Smith'",
        "reason": "A hallucinated document that mentions the name would also pass"
      }
    ],
    "overall": "Assertions check presence but not correctness."
  }
}
```

**Fields:**
- `expectations[]`: Graded expectations with evidence
- `summary`: Aggregate pass/fail counts
- `execution_metrics`: Tool usage and output size (from executor's metrics.json)
- `timing`: Wall clock timing (from timing.json)
- `claims`: Extracted and verified claims from the output
- `user_notes_summary`: Issues flagged by the executor
- `eval_feedback`: (optional) Improvement suggestions for the evals, only present when the grader identifies issues worth raising

---

## metrics.json

Output from the executor agent. Located at `<run-dir>/outputs/metrics.json`.

```json
{
  "tool_calls": {
    "Read": 5,
    "Write": 2,
    "Bash": 8,
    "Edit": 1,
    "Glob": 2,
    "Grep": 0
  },
  "total_tool_calls": 18,
  "total_steps": 6,
  "files_created": ["filled_form.pdf", "field_values.json"],
  "errors_encountered": 0,
  "output_chars": 12450,
  "transcript_chars": 3200
}
```

**Fields:**
- `tool_calls`: Count per tool type
- `total_tool_calls`: Sum of all tool calls
- `total_steps`: Number of major execution steps
- `files_created`: List of output files created
- `errors_encountered`: Number of errors during execution
- `output_chars`: Total character count of output files
- `transcript_chars`: Character count of transcript

---

## timing.json

Wall clock timing for a run. Located at `<run-dir>/timing.json`.

**How to capture:** When a subagent task completes, the task notification includes `total_tokens` and `duration_ms`. Save these immediately — they are not persisted anywhere else and cannot be recovered after the fact.

```json
{
  "total_tokens": 84852,
  "duration_ms": 23332,
  "total_duration_seconds": 23.3,
  "executor_start": "2026-01-15T10:30:00Z",
  "executor_end": "2026-01-15T10:32:45Z",
  "executor_duration_seconds": 165.0,
  "grader_start": "2026-01-15T10:32:46Z",
  "grader_end": "2026-01-15T10:33:12Z",
  "grader_duration_seconds": 26.0
}
```

---

## benchmark.json

Output from Benchmark mode. Located at `benchmarks/<timestamp>/benchmark.json`.

```json
{
  "metadata": {
    "skill_name": "pdf",
    "skill_path": "/path/to/pdf",
    "executor_model": "claude-sonnet-4-20250514",
    "analyzer_model": "most-capable-model",
    "timestamp": "2026-01-15T10:30:00Z",
    "evals_run": [1, 2, 3],
    "runs_per_configuration": 3
  },

  "runs": [
    {
      "eval_id": 1,
      "eval_name": "Ocean",
      "configuration": "with_skill",
      "run_number": 1,
      "result": {
        "pass_rate": 0.85,
        "passed": 6,
        "failed": 1,
        "total": 7,
        "time_seconds": 42.5,
        "tokens": 3800,
        "tool_calls": 18,
        "errors": 0
      },
      "expectations": [
        {"text": "...", "passed": true, "evidence": "..."}
      ],
      "notes": [
        "Used 2023 data, may be stale",
        "Fell back to text overlay for non-fillable fields"
      ]
    }
  ],

  "run_summary": {
    "with_skill": {
      "pass_rate": {"mean": 0.85, "stddev": 0.05, "min": 0.80, "max": 0.90},
      "time_seconds": {"mean": 45.0, "stddev": 12.0, "min": 32.0, "max": 58.0},
      "tokens": {"mean": 3800, "stddev": 400, "min": 3200, "max": 4100}
    },
    "without_skill": {
      "pass_rate": {"mean": 0.35, "stddev": 0.08, "min": 0.28, "max": 0.45},
      "time_seconds": {"mean": 32.0, "stddev": 8.0, "min": 24.0, "max": 42.0},
      "tokens": {"mean": 2100, "stddev": 300, "min": 1800, "max": 2500}
    },
    "delta": {
      "pass_rate": "+0.50",
      "time_seconds": "+13.0",
      "tokens": "+1700"
    }
  },

  "notes": [
    "Assertion 'Output is a PDF file' passes 100% in both configurations - may not differentiate skill value",
    "Eval 3 shows high variance (50% ± 40%) - may be flaky or model-dependent",
    "Without-skill runs consistently fail on table extraction expectations",
    "Skill adds 13s average execution time but improves pass rate by 50%"
  ]
}
```

**Fields:**
- `metadata`: Information about the benchmark run
  - `skill_name`: Name of the skill
  - `timestamp`: When the benchmark was run
  - `evals_run`: List of eval names or IDs
  - `runs_per_configuration`: Number of runs per config (e.g. 3)
- `runs[]`: Individual run results
  - `eval_id`: Numeric eval identifier
  - `eval_name`: Human-readable eval name (used as section header in the viewer)
  - `configuration`: Must be `"with_skill"` or `"without_skill"` (the viewer uses this exact string for grouping and color coding)
  - `run_number`: Integer run number (1, 2, 3...)
  - `result`: Nested object with `pass_rate`, `passed`, `total`, `time_seconds`, `tokens`, `errors`
- `run_summary`: Statistical aggregates per configuration
  - `with_skill` / `without_skill`: Each contains `pass_rate`, `time_seconds`, `tokens` objects with `mean` and `stddev` fields
  - `delta`: Difference strings like `"+0.50"`, `"+13.0"`, `"+1700"`
- `notes`: Freeform observations from the analyzer

**Important:** The viewer reads these field names exactly. Using `config` instead of `configuration`, or putting `pass_rate` at the top level of a run instead of nested under `result`, will cause the viewer to show empty/zero values. Always reference this schema when generating benchmark.json manually.

---

## comparison.json

Output from blind comparator. Located at `<grading-dir>/comparison-N.json`.

```json
{
  "winner": "A",
  "reasoning": "Output A provides a complete solution with proper formatting and all required fields. Output B is missing the date field and has formatting inconsistencies.",
  "rubric": {
    "A": {
      "content": {
        "correctness": 5,
        "completeness": 5,
        "accuracy": 4
      },
      "structure": {
        "organization": 4,
        "formatting": 5,
        "usability": 4
      },
      "content_score": 4.7,
      "structure_score": 4.3,
      "overall_score": 9.0
    },
    "B": {
      "content": {
        "correctness": 3,
        "completeness": 2,
        "accuracy": 3
      },
      "structure": {
        "organization": 3,
        "formatting": 2,
        "usability": 3
      },
      "content_score": 2.7,
      "structure_score": 2.7,
      "overall_score": 5.4
    }
  },
  "output_quality": {
    "A": {
      "score": 9,
      "strengths": ["Complete solution", "Well-formatted", "All fields present"],
      "weaknesses": ["Minor style inconsistency in header"]
    },
    "B": {
      "score": 5,
      "strengths": ["Readable output", "Correct basic structure"],
      "weaknesses": ["Missing date field", "Formatting inconsistencies", "Partial data extraction"]
    }
  },
  "expectation_results": {
    "A": {
      "passed": 4,
      "total": 5,
      "pass_rate": 0.80,
      "details": [
        {"text": "Output includes name", "passed": true}
      ]
    },
    "B": {
      "passed": 3,
      "total": 5,
      "pass_rate": 0.60,
      "details": [
        {"text": "Output includes name", "passed": true}
      ]
    }
  }
}
```

---

## analysis.json

Output from post-hoc analyzer. Located at `<grading-dir>/analysis.json`.

```json
{
  "comparison_summary": {
    "winner": "A",
    "winner_skill": "path/to/winner/skill",
    "loser_skill": "path/to/loser/skill",
    "comparator_reasoning": "Brief summary of why comparator chose winner"
  },
  "winner_strengths": [
    "Clear step-by-step instructions for handling multi-page documents",
    "Included validation script that caught formatting errors"
  ],
  "loser_weaknesses": [
    "Vague instruction 'process the document appropriately' led to inconsistent behavior",
    "No script for validation, agent had to improvise"
  ],
  "instruction_following": {
    "winner": {
      "score": 9,
      "issues": ["Minor: skipped optional logging step"]
    },
    "loser": {
      "score": 6,
      "issues": [
        "Did not use the skill's formatting template",
        "Invented own approach instead of following step 3"
      ]
    }
  },
  "improvement_suggestions": [
    {
      "priority": "high",
      "category": "instructions",
      "suggestion": "Replace 'process the document appropriately' with explicit steps",
      "expected_impact": "Would eliminate ambiguity that caused inconsistent behavior"
    }
  ],
  "transcript_insights": {
    "winner_execution_pattern": "Read skill -> Followed 5-step process -> Used validation script",
    "loser_execution_pattern": "Read skill -> Unclear on approach -> Tried 3 different methods"
  }
}
```

FILE:scripts/__init__.py

FILE:scripts/aggregate_benchmark.py
#!/usr/bin/env python3
"""
Aggregate individual run results into benchmark summary statistics.

Reads grading.json files from run directories and produces:
- run_summary with mean, stddev, min, max for each metric
- delta between with_skill and without_skill configurations

Usage:
    python aggregate_benchmark.py <benchmark_dir>

Example:
    python aggregate_benchmark.py benchmarks/2026-01-15T10-30-00/

The script supports two directory layouts:

    Workspace layout (from skill-creator iterations):
    <benchmark_dir>/
    └── eval-N/
        ├── with_skill/
        │   ├── run-1/grading.json
        │   └── run-2/grading.json
        └── without_skill/
            ├── run-1/grading.json
            └── run-2/grading.json

    Legacy layout (with runs/ subdirectory):
    <benchmark_dir>/
    └── runs/
        └── eval-N/
            ├── with_skill/
            │   └── run-1/grading.json
            └── without_skill/
                └── run-1/grading.json
"""

import argparse
import json
import math
import sys
from datetime import datetime, timezone
from pathlib import Path


def calculate_stats(values: list[float]) -> dict:
    """Calculate mean, stddev, min, max for a list of values."""
    if not values:
        return {"mean": 0.0, "stddev": 0.0, "min": 0.0, "max": 0.0}

    n = len(values)
    mean = sum(values) / n

    if n > 1:
        variance = sum((x - mean) ** 2 for x in values) / (n - 1)
        stddev = math.sqrt(variance)
    else:
        stddev = 0.0

    return {
        "mean": round(mean, 4),
        "stddev": round(stddev, 4),
        "min": round(min(values), 4),
        "max": round(max(values), 4)
    }


def load_run_results(benchmark_dir: Path) -> dict:
    """
    Load all run results from a benchmark directory.

    Returns dict keyed by config name (e.g. "with_skill"/"without_skill",
    or "new_skill"/"old_skill"), each containing a list of run results.
    """
    # Support both layouts: eval dirs directly under benchmark_dir, or under runs/
    runs_dir = benchmark_dir / "runs"
    if runs_dir.exists():
        search_dir = runs_dir
    elif list(benchmark_dir.glob("eval-*")):
        search_dir = benchmark_dir
    else:
        print(f"No eval directories found in {benchmark_dir} or {benchmark_dir / 'runs'}")
        return {}

    results: dict[str, list] = {}

    for eval_idx, eval_dir in enumerate(sorted(search_dir.glob("eval-*"))):
        metadata_path = eval_dir / "eval_metadata.json"
        if metadata_path.exists():
            try:
                with open(metadata_path) as mf:
                    eval_id = json.load(mf).get("eval_id", eval_idx)
            except (json.JSONDecodeError, OSError):
                eval_id = eval_idx
        else:
            try:
                eval_id = int(eval_dir.name.split("-")[1])
            except ValueError:
                eval_id = eval_idx

        # Discover config directories dynamically rather than hardcoding names
        for config_dir in sorted(eval_dir.iterdir()):
            if not config_dir.is_dir():
                continue
            # Skip non-config directories (inputs, outputs, etc.)
            if not list(config_dir.glob("run-*")):
                continue
            config = config_dir.name
            if config not in results:
                results[config] = []

            for run_dir in sorted(config_dir.glob("run-*")):
                run_number = int(run_dir.name.split("-")[1])
                grading_file = run_dir / "grading.json"

                if not grading_file.exists():
                    print(f"Warning: grading.json not found in {run_dir}")
                    continue

                try:
                    with open(grading_file) as f:
                        grading = json.load(f)
                except json.JSONDecodeError as e:
                    print(f"Warning: Invalid JSON in {grading_file}: {e}")
                    continue

                # Extract metrics
                result = {
                    "eval_id": eval_id,
                    "run_number": run_number,
                    "pass_rate": grading.get("summary", {}).get("pass_rate", 0.0),
                    "passed": grading.get("summary", {}).get("passed", 0),
                    "failed": grading.get("summary", {}).get("failed", 0),
                    "total": grading.get("summary", {}).get("total", 0),
                }

                # Extract timing — check grading.json first, then sibling timing.json
                timing = grading.get("timing", {})
                result["time_seconds"] = timing.get("total_duration_seconds", 0.0)
                timing_file = run_dir / "timing.json"
                if result["time_seconds"] == 0.0 and timing_file.exists():
                    try:
                        with open(timing_file) as tf:
                            timing_data = json.load(tf)
                        result["time_seconds"] = timing_data.get("total_duration_seconds", 0.0)
                        result["tokens"] = timing_data.get("total_tokens", 0)
                    except json.JSONDecodeError:
                        pass

                # Extract metrics if available
                metrics = grading.get("execution_metrics", {})
                result["tool_calls"] = metrics.get("total_tool_calls", 0)
                if not result.get("tokens"):
                    result["tokens"] = metrics.get("output_chars", 0)
                result["errors"] = metrics.get("errors_encountered", 0)

                # Extract expectations — viewer requires fields: text, passed, evidence
                raw_expectations = grading.get("expectations", [])
                for exp in raw_expectations:
                    if "text" not in exp or "passed" not in exp:
                        print(f"Warning: expectation in {grading_file} missing required fields (text, passed, evidence): {exp}")
                result["expectations"] = raw_expectations

                # Extract notes from user_notes_summary
                notes_summary = grading.get("user_notes_summary", {})
                notes = []
                notes.extend(notes_summary.get("uncertainties", []))
                notes.extend(notes_summary.get("needs_review", []))
                notes.extend(notes_summary.get("workarounds", []))
                result["notes"] = notes

                results[config].append(result)

    return results


def aggregate_results(results: dict) -> dict:
    """
    Aggregate run results into summary statistics.

    Returns run_summary with stats for each configuration and delta.
    """
    run_summary = {}
    configs = list(results.keys())

    for config in configs:
        runs = results.get(config, [])

        if not runs:
            run_summary[config] = {
                "pass_rate": {"mean": 0.0, "stddev": 0.0, "min": 0.0, "max": 0.0},
                "time_seconds": {"mean": 0.0, "stddev": 0.0, "min": 0.0, "max": 0.0},
                "tokens": {"mean": 0, "stddev": 0, "min": 0, "max": 0}
            }
            continue

        pass_rates = [r["pass_rate"] for r in runs]
        times = [r["time_seconds"] for r in runs]
        tokens = [r.get("tokens", 0) for r in runs]

        run_summary[config] = {
            "pass_rate": calculate_stats(pass_rates),
            "time_seconds": calculate_stats(times),
            "tokens": calculate_stats(tokens)
        }

    # Calculate delta between the first two configs (if two exist)
    if len(configs) >= 2:
        primary = run_summary.get(configs[0], {})
        baseline = run_summary.get(configs[1], {})
    else:
        primary = run_summary.get(configs[0], {}) if configs else {}
        baseline = {}

    delta_pass_rate = primary.get("pass_rate", {}).get("mean", 0) - baseline.get("pass_rate", {}).get("mean", 0)
    delta_time = primary.get("time_seconds", {}).get("mean", 0) - baseline.get("time_seconds", {}).get("mean", 0)
    delta_tokens = primary.get("tokens", {}).get("mean", 0) - baseline.get("tokens", {}).get("mean", 0)

    run_summary["delta"] = {
        "pass_rate": f"{delta_pass_rate:+.2f}",
        "time_seconds": f"{delta_time:+.1f}",
        "tokens": f"{delta_tokens:+.0f}"
    }

    return run_summary


def generate_benchmark(benchmark_dir: Path, skill_name: str = "", skill_path: str = "") -> dict:
    """
    Generate complete benchmark.json from run results.
    """
    results = load_run_results(benchmark_dir)
    run_summary = aggregate_results(results)

    # Build runs array for benchmark.json
    runs = []
    for config in results:
        for result in results[config]:
            runs.append({
                "eval_id": result["eval_id"],
                "configuration": config,
                "run_number": result["run_number"],
                "result": {
                    "pass_rate": result["pass_rate"],
                    "passed": result["passed"],
                    "failed": result["failed"],
                    "total": result["total"],
                    "time_seconds": result["time_seconds"],
                    "tokens": result.get("tokens", 0),
                    "tool_calls": result.get("tool_calls", 0),
                    "errors": result.get("errors", 0)
                },
                "expectations": result["expectations"],
                "notes": result["notes"]
            })

    # Determine eval IDs from results
    eval_ids = sorted(set(
        r["eval_id"]
        for config in results.values()
        for r in config
    ))

    benchmark = {
        "metadata": {
            "skill_name": skill_name or "<skill-name>",
            "skill_path": skill_path or "<path/to/skill>",
            "executor_model": "<model-name>",
            "analyzer_model": "<model-name>",
            "timestamp": datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ"),
            "evals_run": eval_ids,
            "runs_per_configuration": 3
        },
        "runs": runs,
        "run_summary": run_summary,
        "notes": []  # To be filled by analyzer
    }

    return benchmark


def generate_markdown(benchmark: dict) -> str:
    """Generate human-readable benchmark.md from benchmark data."""
    metadata = benchmark["metadata"]
    run_summary = benchmark["run_summary"]

    # Determine config names (excluding "delta")
    configs = [k for k in run_summary if k != "delta"]
    config_a = configs[0] if len(configs) >= 1 else "config_a"
    config_b = configs[1] if len(configs) >= 2 else "config_b"
    label_a = config_a.replace("_", " ").title()
    label_b = config_b.replace("_", " ").title()

    lines = [
        f"# Skill Benchmark: {metadata['skill_name']}",
        "",
        f"**Model**: {metadata['executor_model']}",
        f"**Date**: {metadata['timestamp']}",
        f"**Evals**: {', '.join(map(str, metadata['evals_run']))} ({metadata['runs_per_configuration']} runs each per configuration)",
        "",
        "## Summary",
        "",
        f"| Metric | {label_a} | {label_b} | Delta |",
        "|--------|------------|---------------|-------|",
    ]

    a_summary = run_summary.get(config_a, {})
    b_summary = run_summary.get(config_b, {})
    delta = run_summary.get("delta", {})

    # Format pass rate
    a_pr = a_summary.get("pass_rate", {})
    b_pr = b_summary.get("pass_rate", {})
    lines.append(f"| Pass Rate | {a_pr.get('mean', 0)*100:.0f}% ± {a_pr.get('stddev', 0)*100:.0f}% | {b_pr.get('mean', 0)*100:.0f}% ± {b_pr.get('stddev', 0)*100:.0f}% | {delta.get('pass_rate', '—')} |")

    # Format time
    a_time = a_summary.get("time_seconds", {})
    b_time = b_summary.get("time_seconds", {})
    lines.append(f"| Time | {a_time.get('mean', 0):.1f}s ± {a_time.get('stddev', 0):.1f}s | {b_time.get('mean', 0):.1f}s ± {b_time.get('stddev', 0):.1f}s | {delta.get('time_seconds', '—')}s |")

    # Format tokens
    a_tokens = a_summary.get("tokens", {})
    b_tokens = b_summary.get("tokens", {})
    lines.append(f"| Tokens | {a_tokens.get('mean', 0):.0f} ± {a_tokens.get('stddev', 0):.0f} | {b_tokens.get('mean', 0):.0f} ± {b_tokens.get('stddev', 0):.0f} | {delta.get('tokens', '—')} |")

    # Notes section
    if benchmark.get("notes"):
        lines.extend([
            "",
            "## Notes",
            ""
        ])
        for note in benchmark["notes"]:
            lines.append(f"- {note}")

    return "\n".join(lines)


def main():
    parser = argparse.ArgumentParser(
        description="Aggregate benchmark run results into summary statistics"
    )
    parser.add_argument(
        "benchmark_dir",
        type=Path,
        help="Path to the benchmark directory"
    )
    parser.add_argument(
        "--skill-name",
        default="",
        help="Name of the skill being benchmarked"
    )
    parser.add_argument(
        "--skill-path",
        default="",
        help="Path to the skill being benchmarked"
    )
    parser.add_argument(
        "--output", "-o",
        type=Path,
        help="Output path for benchmark.json (default: <benchmark_dir>/benchmark.json)"
    )

    args = parser.parse_args()

    if not args.benchmark_dir.exists():
        print(f"Directory not found: {args.benchmark_dir}")
        sys.exit(1)

    # Generate benchmark
    benchmark = generate_benchmark(args.benchmark_dir, args.skill_name, args.skill_path)

    # Determine output paths
    output_json = args.output or (args.benchmark_dir / "benchmark.json")
    output_md = output_json.with_suffix(".md")

    # Write benchmark.json
    with open(output_json, "w") as f:
        json.dump(benchmark, f, indent=2)
    print(f"Generated: {output_json}")

    # Write benchmark.md
    markdown = generate_markdown(benchmark)
    with open(output_md, "w") as f:
        f.write(markdown)
    print(f"Generated: {output_md}")

    # Print summary
    run_summary = benchmark["run_summary"]
    configs = [k for k in run_summary if k != "delta"]
    delta = run_summary.get("delta", {})

    print(f"\nSummary:")
    for config in configs:
        pr = run_summary[config]["pass_rate"]["mean"]
        label = config.replace("_", " ").title()
        print(f"  {label}: {pr*100:.1f}% pass rate")
    print(f"  Delta:         {delta.get('pass_rate', '—')}")


if __name__ == "__main__":
    main()

FILE:scripts/generate_report.py
#!/usr/bin/env python3
"""Generate an HTML report from run_loop.py output.

Takes the JSON output from run_loop.py and generates a visual HTML report
showing each description attempt with check/x for each test case.
Distinguishes between train and test queries.
"""

import argparse
import html
import json
import sys
from pathlib import Path


def generate_html(data: dict, auto_refresh: bool = False, skill_name: str = "") -> str:
    """Generate HTML report from loop output data. If auto_refresh is True, adds a meta refresh tag."""
    history = data.get("history", [])
    holdout = data.get("holdout", 0)
    title_prefix = html.escape(skill_name + " \u2014 ") if skill_name else ""

    # Get all unique queries from train and test sets, with should_trigger info
    train_queries: list[dict] = []
    test_queries: list[dict] = []
    if history:
        for r in history[0].get("train_results", history[0].get("results", [])):
            train_queries.append({"query": r["query"], "should_trigger": r.get("should_trigger", True)})
        if history[0].get("test_results"):
            for r in history[0].get("test_results", []):
                test_queries.append({"query": r["query"], "should_trigger": r.get("should_trigger", True)})

    refresh_tag = '    <meta http-equiv="refresh" content="5">\n' if auto_refresh else ""

    html_parts = ["""<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
""" + refresh_tag + """    <title>""" + title_prefix + """Skill Description Optimization</title>
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Poppins:wght@500;600&family=Lora:wght@400;500&display=swap" rel="stylesheet">
    <style>
        body {
            font-family: 'Lora', Georgia, serif;
            max-width: 100%;
            margin: 0 auto;
            padding: 20px;
            background: #faf9f5;
            color: #141413;
        }
        h1 { font-family: 'Poppins', sans-serif; color: #141413; }
        .explainer {
            background: white;
            padding: 15px;
            border-radius: 6px;
            margin-bottom: 20px;
            border: 1px solid #e8e6dc;
            color: #b0aea5;
            font-size: 0.875rem;
            line-height: 1.6;
        }
        .summary {
            background: white;
            padding: 15px;
            border-radius: 6px;
            margin-bottom: 20px;
            border: 1px solid #e8e6dc;
        }
        .summary p { margin: 5px 0; }
        .best { color: #788c5d; font-weight: bold; }
        .table-container {
            overflow-x: auto;
            width: 100%;
        }
        table {
            border-collapse: collapse;
            background: white;
            border: 1px solid #e8e6dc;
            border-radius: 6px;
            font-size: 12px;
            min-width: 100%;
        }
        th, td {
            padding: 8px;
            text-align: left;
            border: 1px solid #e8e6dc;
            white-space: normal;
            word-wrap: break-word;
        }
        th {
            font-family: 'Poppins', sans-serif;
            background: #141413;
            color: #faf9f5;
            font-weight: 500;
        }
        th.test-col {
            background: #6a9bcc;
        }
        th.query-col { min-width: 200px; }
        td.description {
            font-family: monospace;
            font-size: 11px;
            word-wrap: break-word;
            max-width: 400px;
        }
        td.result {
            text-align: center;
            font-size: 16px;
            min-width: 40px;
        }
        td.test-result {
            background: #f0f6fc;
        }
        .pass { color: #788c5d; }
        .fail { color: #c44; }
        .rate {
            font-size: 9px;
            color: #b0aea5;
            display: block;
        }
        tr:hover { background: #faf9f5; }
        .score {
            display: inline-block;
            padding: 2px 6px;
            border-radius: 4px;
            font-weight: bold;
            font-size: 11px;
        }
        .score-good { background: #eef2e8; color: #788c5d; }
        .score-ok { background: #fef3c7; color: #d97706; }
        .score-bad { background: #fceaea; color: #c44; }
        .train-label { color: #b0aea5; font-size: 10px; }
        .test-label { color: #6a9bcc; font-size: 10px; font-weight: bold; }
        .best-row { background: #f5f8f2; }
        th.positive-col { border-bottom: 3px solid #788c5d; }
        th.negative-col { border-bottom: 3px solid #c44; }
        th.test-col.positive-col { border-bottom: 3px solid #788c5d; }
        th.test-col.negative-col { border-bottom: 3px solid #c44; }
        .legend { font-family: 'Poppins', sans-serif; display: flex; gap: 20px; margin-bottom: 10px; font-size: 13px; align-items: center; }
        .legend-item { display: flex; align-items: center; gap: 6px; }
        .legend-swatch { width: 16px; height: 16px; border-radius: 3px; display: inline-block; }
        .swatch-positive { background: #141413; border-bottom: 3px solid #788c5d; }
        .swatch-negative { background: #141413; border-bottom: 3px solid #c44; }
        .swatch-test { background: #6a9bcc; }
        .swatch-train { background: #141413; }
    </style>
</head>
<body>
    <h1>""" + title_prefix + """Skill Description Optimization</h1>
    <div class="explainer">
        <strong>Optimizing your skill's description.</strong> This page updates automatically as Claude tests different versions of your skill's description. Each row is an iteration — a new description attempt. The columns show test queries: green checkmarks mean the skill triggered correctly (or correctly didn't trigger), red crosses mean it got it wrong. The "Train" score shows performance on queries used to improve the description; the "Test" score shows performance on held-out queries the optimizer hasn't seen. When it's done, Claude will apply the best-performing description to your skill.
    </div>
"""]

    # Summary section
    best_test_score = data.get('best_test_score')
    best_train_score = data.get('best_train_score')
    html_parts.append(f"""
    <div class="summary">
        <p><strong>Original:</strong> {html.escape(data.get('original_description', 'N/A'))}</p>
        <p class="best"><strong>Best:</strong> {html.escape(data.get('best_description', 'N/A'))}</p>
        <p><strong>Best Score:</strong> {data.get('best_score', 'N/A')} {'(test)' if best_test_score else '(train)'}</p>
        <p><strong>Iterations:</strong> {data.get('iterations_run', 0)} | <strong>Train:</strong> {data.get('train_size', '?')} | <strong>Test:</strong> {data.get('test_size', '?')}</p>
    </div>
""")

    # Legend
    html_parts.append("""
    <div class="legend">
        <span style="font-weight:600">Query columns:</span>
        <span class="legend-item"><span class="legend-swatch swatch-positive"></span> Should trigger</span>
        <span class="legend-item"><span class="legend-swatch swatch-negative"></span> Should NOT trigger</span>
        <span class="legend-item"><span class="legend-swatch swatch-train"></span> Train</span>
        <span class="legend-item"><span class="legend-swatch swatch-test"></span> Test</span>
    </div>
""")

    # Table header
    html_parts.append("""
    <div class="table-container">
    <table>
        <thead>
            <tr>
                <th>Iter</th>
                <th>Train</th>
                <th>Test</th>
                <th class="query-col">Description</th>
""")

    # Add column headers for train queries
    for qinfo in train_queries:
        polarity = "positive-col" if qinfo["should_trigger"] else "negative-col"
        html_parts.append(f'                <th class="{polarity}">{html.escape(qinfo["query"])}</th>\n')

    # Add column headers for test queries (different color)
    for qinfo in test_queries:
        polarity = "positive-col" if qinfo["should_trigger"] else "negative-col"
        html_parts.append(f'                <th class="test-col {polarity}">{html.escape(qinfo["query"])}</th>\n')

    html_parts.append("""            </tr>
        </thead>
        <tbody>
""")

    # Find best iteration for highlighting
    if test_queries:
        best_iter = max(history, key=lambda h: h.get("test_passed") or 0).get("iteration")
    else:
        best_iter = max(history, key=lambda h: h.get("train_passed", h.get("passed", 0))).get("iteration")

    # Add rows for each iteration
    for h in history:
        iteration = h.get("iteration", "?")
        train_passed = h.get("train_passed", h.get("passed", 0))
        train_total = h.get("train_total", h.get("total", 0))
        test_passed = h.get("test_passed")
        test_total = h.get("test_total")
        description = h.get("description", "")
        train_results = h.get("train_results", h.get("results", []))
        test_results = h.get("test_results", [])

        # Create lookups for results by query
        train_by_query = {r["query"]: r for r in train_results}
        test_by_query = {r["query"]: r for r in test_results} if test_results else {}

        # Compute aggregate correct/total runs across all retries
        def aggregate_runs(results: list[dict]) -> tuple[int, int]:
            correct = 0
            total = 0
            for r in results:
                runs = r.get("runs", 0)
                triggers = r.get("triggers", 0)
                total += runs
                if r.get("should_trigger", True):
                    correct += triggers
                else:
                    correct += runs - triggers
            return correct, total

        train_correct, train_runs = aggregate_runs(train_results)
        test_correct, test_runs = aggregate_runs(test_results)

        # Determine score classes
        def score_class(correct: int, total: int) -> str:
            if total > 0:
                ratio = correct / total
                if ratio >= 0.8:
                    return "score-good"
                elif ratio >= 0.5:
                    return "score-ok"
            return "score-bad"

        train_class = score_class(train_correct, train_runs)
        test_class = score_class(test_correct, test_runs)

        row_class = "best-row" if iteration == best_iter else ""

        html_parts.append(f"""            <tr class="{row_class}">
                <td>{iteration}</td>
                <td><span class="score {train_class}">{train_correct}/{train_runs}</span></td>
                <td><span class="score {test_class}">{test_correct}/{test_runs}</span></td>
                <td class="description">{html.escape(description)}</td>
""")

        # Add result for each train query
        for qinfo in train_queries:
            r = train_by_query.get(qinfo["query"], {})
            did_pass = r.get("pass", False)
            triggers = r.get("triggers", 0)
            runs = r.get("runs", 0)

            icon = "✓" if did_pass else "✗"
            css_class = "pass" if did_pass else "fail"

            html_parts.append(f'                <td class="result {css_class}">{icon}<span class="rate">{triggers}/{runs}</span></td>\n')

        # Add result for each test query (with different background)
        for qinfo in test_queries:
            r = test_by_query.get(qinfo["query"], {})
            did_pass = r.get("pass", False)
            triggers = r.get("triggers", 0)
            runs = r.get("runs", 0)

            icon = "✓" if did_pass else "✗"
            css_class = "pass" if did_pass else "fail"

            html_parts.append(f'                <td class="result test-result {css_class}">{icon}<span class="rate">{triggers}/{runs}</span></td>\n')

        html_parts.append("            </tr>\n")

    html_parts.append("""        </tbody>
    </table>
    </div>
""")

    html_parts.append("""
</body>
</html>
""")

    return "".join(html_parts)


def main():
    parser = argparse.ArgumentParser(description="Generate HTML report from run_loop output")
    parser.add_argument("input", help="Path to JSON output from run_loop.py (or - for stdin)")
    parser.add_argument("-o", "--output", default=None, help="Output HTML file (default: stdout)")
    parser.add_argument("--skill-name", default="", help="Skill name to include in the report title")
    args = parser.parse_args()

    if args.input == "-":
        data = json.load(sys.stdin)
    else:
        data = json.loads(Path(args.input).read_text())

    html_output = generate_html(data, skill_name=args.skill_name)

    if args.output:
        Path(args.output).write_text(html_output)
        print(f"Report written to {args.output}", file=sys.stderr)
    else:
        print(html_output)


if __name__ == "__main__":
    main()

FILE:scripts/improve_description.py
#!/usr/bin/env python3
"""Improve a skill description based on eval results.

Takes eval results (from run_eval.py) and generates an improved description
by calling `claude -p` as a subprocess (same auth pattern as run_eval.py —
uses the session's Claude Code auth, no separate ANTHROPIC_API_KEY needed).
"""

import argparse
import json
import os
import re
import subprocess
import sys
from pathlib import Path

from scripts.utils import parse_skill_md


def _call_claude(prompt: str, model: str | None, timeout: int = 300) -> str:
    """Run `claude -p` with the prompt on stdin and return the text response.

    Prompt goes over stdin (not argv) because it embeds the full SKILL.md
    body and can easily exceed comfortable argv length.
    """
    cmd = ["claude", "-p", "--output-format", "text"]
    if model:
        cmd.extend(["--model", model])

    # Remove CLAUDECODE env var to allow nesting claude -p inside a
    # Claude Code session. The guard is for interactive terminal conflicts;
    # programmatic subprocess usage is safe. Same pattern as run_eval.py.
    env = {k: v for k, v in os.environ.items() if k != "CLAUDECODE"}

    result = subprocess.run(
        cmd,
        input=prompt,
        capture_output=True,
        text=True,
        env=env,
        timeout=timeout,
    )
    if result.returncode != 0:
        raise RuntimeError(
            f"claude -p exited {result.returncode}\nstderr: {result.stderr}"
        )
    return result.stdout


def improve_description(
    skill_name: str,
    skill_content: str,
    current_description: str,
    eval_results: dict,
    history: list[dict],
    model: str,
    test_results: dict | None = None,
    log_dir: Path | None = None,
    iteration: int | None = None,
) -> str:
    """Call Claude to improve the description based on eval results."""
    failed_triggers = [
        r for r in eval_results["results"]
        if r["should_trigger"] and not r["pass"]
    ]
    false_triggers = [
        r for r in eval_results["results"]
        if not r["should_trigger"] and not r["pass"]
    ]

    # Build scores summary
    train_score = f"{eval_results['summary']['passed']}/{eval_results['summary']['total']}"
    if test_results:
        test_score = f"{test_results['summary']['passed']}/{test_results['summary']['total']}"
        scores_summary = f"Train: {train_score}, Test: {test_score}"
    else:
        scores_summary = f"Train: {train_score}"

    prompt = f"""You are optimizing a skill description for a Claude Code skill called "{skill_name}". A "skill" is sort of like a prompt, but with progressive disclosure -- there's a title and description that Claude sees when deciding whether to use the skill, and then if it does use the skill, it reads the .md file which has lots more details and potentially links to other resources in the skill folder like helper files and scripts and additional documentation or examples.

The description appears in Claude's "available_skills" list. When a user sends a query, Claude decides whether to invoke the skill based solely on the title and on this description. Your goal is to write a description that triggers for relevant queries, and doesn't trigger for irrelevant ones.

Here's the current description:
<current_description>
"{current_description}"
</current_description>

Current scores ({scores_summary}):
<scores_summary>
"""
    if failed_triggers:
        prompt += "FAILED TO TRIGGER (should have triggered but didn't):\n"
        for r in failed_triggers:
            prompt += f'  - "{r["query"]}" (triggered {r["triggers"]}/{r["runs"]} times)\n'
        prompt += "\n"

    if false_triggers:
        prompt += "FALSE TRIGGERS (triggered but shouldn't have):\n"
        for r in false_triggers:
            prompt += f'  - "{r["query"]}" (triggered {r["triggers"]}/{r["runs"]} times)\n'
        prompt += "\n"

    if history:
        prompt += "PREVIOUS ATTEMPTS (do NOT repeat these — try something structurally different):\n\n"
        for h in history:
            train_s = f"{h.get('train_passed', h.get('passed', 0))}/{h.get('train_total', h.get('total', 0))}"
            test_s = f"{h.get('test_passed', '?')}/{h.get('test_total', '?')}" if h.get('test_passed') is not None else None
            score_str = f"train={train_s}" + (f", test={test_s}" if test_s else "")
            prompt += f'<attempt {score_str}>\n'
            prompt += f'Description: "{h["description"]}"\n'
            if "results" in h:
                prompt += "Train results:\n"
                for r in h["results"]:
                    status = "PASS" if r["pass"] else "FAIL"
                    prompt += f'  [{status}] "{r["query"][:80]}" (triggered {r["triggers"]}/{r["runs"]})\n'
            if h.get("note"):
                prompt += f'Note: {h["note"]}\n'
            prompt += "</attempt>\n\n"

    prompt += f"""</scores_summary>

Skill content (for context on what the skill does):
<skill_content>
{skill_content}
</skill_content>

Based on the failures, write a new and improved description that is more likely to trigger correctly. When I say "based on the failures", it's a bit of a tricky line to walk because we don't want to overfit to the specific cases you're seeing. So what I DON'T want you to do is produce an ever-expanding list of specific queries that this skill should or shouldn't trigger for. Instead, try to generalize from the failures to broader categories of user intent and situations where this skill would be useful or not useful. The reason for this is twofold:

1. Avoid overfitting
2. The list might get loooong and it's injected into ALL queries and there might be a lot of skills, so we don't want to blow too much space on any given description.

Concretely, your description should not be more than about 100-200 words, even if that comes at the cost of accuracy. There is a hard limit of 1024 characters — descriptions over that will be truncated, so stay comfortably under it.

Here are some tips that we've found to work well in writing these descriptions:
- The skill should be phrased in the imperative -- "Use this skill for" rather than "this skill does"
- The skill description should focus on the user's intent, what they are trying to achieve, vs. the implementation details of how the skill works.
- The description competes with other skills for Claude's attention — make it distinctive and immediately recognizable.
- If you're getting lots of failures after repeated attempts, change things up. Try different sentence structures or wordings.

I'd encourage you to be creative and mix up the style in different iterations since you'll have multiple opportunities to try different approaches and we'll just grab the highest-scoring one at the end. 

Please respond with only the new description text in <new_description> tags, nothing else."""

    text = _call_claude(prompt, model)

    match = re.search(r"<new_description>(.*?)</new_description>", text, re.DOTALL)
    description = match.group(1).strip().strip('"') if match else text.strip().strip('"')

    transcript: dict = {
        "iteration": iteration,
        "prompt": prompt,
        "response": text,
        "parsed_description": description,
        "char_count": len(description),
        "over_limit": len(description) > 1024,
    }

    # Safety net: the prompt already states the 1024-char hard limit, but if
    # the model blew past it anyway, make one fresh single-turn call that
    # quotes the too-long version and asks for a shorter rewrite. (The old
    # SDK path did this as a true multi-turn; `claude -p` is one-shot, so we
    # inline the prior output into the new prompt instead.)
    if len(description) > 1024:
        shorten_prompt = (
            f"{prompt}\n\n"
            f"---\n\n"
            f"A previous attempt produced this description, which at "
            f"{len(description)} characters is over the 1024-character hard limit:\n\n"
            f'"{description}"\n\n'
            f"Rewrite it to be under 1024 characters while keeping the most "
            f"important trigger words and intent coverage. Respond with only "
            f"the new description in <new_description> tags."
        )
        shorten_text = _call_claude(shorten_prompt, model)
        match = re.search(r"<new_description>(.*?)</new_description>", shorten_text, re.DOTALL)
        shortened = match.group(1).strip().strip('"') if match else shorten_text.strip().strip('"')

        transcript["rewrite_prompt"] = shorten_prompt
        transcript["rewrite_response"] = shorten_text
        transcript["rewrite_description"] = shortened
        transcript["rewrite_char_count"] = len(shortened)
        description = shortened

    transcript["final_description"] = description

    if log_dir:
        log_dir.mkdir(parents=True, exist_ok=True)
        log_file = log_dir / f"improve_iter_{iteration or 'unknown'}.json"
        log_file.write_text(json.dumps(transcript, indent=2))

    return description


def main():
    parser = argparse.ArgumentParser(description="Improve a skill description based on eval results")
    parser.add_argument("--eval-results", required=True, help="Path to eval results JSON (from run_eval.py)")
    parser.add_argument("--skill-path", required=True, help="Path to skill directory")
    parser.add_argument("--history", default=None, help="Path to history JSON (previous attempts)")
    parser.add_argument("--model", required=True, help="Model for improvement")
    parser.add_argument("--verbose", action="store_true", help="Print thinking to stderr")
    args = parser.parse_args()

    skill_path = Path(args.skill_path)
    if not (skill_path / "SKILL.md").exists():
        print(f"Error: No SKILL.md found at {skill_path}", file=sys.stderr)
        sys.exit(1)

    eval_results = json.loads(Path(args.eval_results).read_text())
    history = []
    if args.history:
        history = json.loads(Path(args.history).read_text())

    name, _, content = parse_skill_md(skill_path)
    current_description = eval_results["description"]

    if args.verbose:
        print(f"Current: {current_description}", file=sys.stderr)
        print(f"Score: {eval_results['summary']['passed']}/{eval_results['summary']['total']}", file=sys.stderr)

    new_description = improve_description(
        skill_name=name,
        skill_content=content,
        current_description=current_description,
        eval_results=eval_results,
        history=history,
        model=args.model,
    )

    if args.verbose:
        print(f"Improved: {new_description}", file=sys.stderr)

    # Output as JSON with both the new description and updated history
    output = {
        "description": new_description,
        "history": history + [{
            "description": current_description,
            "passed": eval_results["summary"]["passed"],
            "failed": eval_results["summary"]["failed"],
            "total": eval_results["summary"]["total"],
            "results": eval_results["results"],
        }],
    }
    print(json.dumps(output, indent=2))


if __name__ == "__main__":
    main()

FILE:scripts/package_skill.py
#!/usr/bin/env python3
"""
Skill Packager - Creates a distributable .skill file of a skill folder

Usage:
    python utils/package_skill.py <path/to/skill-folder> [output-directory]

Example:
    python utils/package_skill.py skills/public/my-skill
    python utils/package_skill.py skills/public/my-skill ./dist
"""

import fnmatch
import sys
import zipfile
from pathlib import Path
from scripts.quick_validate import validate_skill

# Patterns to exclude when packaging skills.
EXCLUDE_DIRS = {"__pycache__", "node_modules"}
EXCLUDE_GLOBS = {"*.pyc"}
EXCLUDE_FILES = {".DS_Store"}
# Directories excluded only at the skill root (not when nested deeper).
ROOT_EXCLUDE_DIRS = {"evals"}


def should_exclude(rel_path: Path) -> bool:
    """Check if a path should be excluded from packaging."""
    parts = rel_path.parts
    if any(part in EXCLUDE_DIRS for part in parts):
        return True
    # rel_path is relative to skill_path.parent, so parts[0] is the skill
    # folder name and parts[1] (if present) is the first subdir.
    if len(parts) > 1 and parts[1] in ROOT_EXCLUDE_DIRS:
        return True
    name = rel_path.name
    if name in EXCLUDE_FILES:
        return True
    return any(fnmatch.fnmatch(name, pat) for pat in EXCLUDE_GLOBS)


def package_skill(skill_path, output_dir=None):
    """
    Package a skill folder into a .skill file.

    Args:
        skill_path: Path to the skill folder
        output_dir: Optional output directory for the .skill file (defaults to current directory)

    Returns:
        Path to the created .skill file, or None if error
    """
    skill_path = Path(skill_path).resolve()

    # Validate skill folder exists
    if not skill_path.exists():
        print(f"❌ Error: Skill folder not found: {skill_path}")
        return None

    if not skill_path.is_dir():
        print(f"❌ Error: Path is not a directory: {skill_path}")
        return None

    # Validate SKILL.md exists
    skill_md = skill_path / "SKILL.md"
    if not skill_md.exists():
        print(f"❌ Error: SKILL.md not found in {skill_path}")
        return None

    # Run validation before packaging
    print("🔍 Validating skill...")
    valid, message = validate_skill(skill_path)
    if not valid:
        print(f"❌ Validation failed: {message}")
        print("   Please fix the validation errors before packaging.")
        return None
    print(f"✅ {message}\n")

    # Determine output location
    skill_name = skill_path.name
    if output_dir:
        output_path = Path(output_dir).resolve()
        output_path.mkdir(parents=True, exist_ok=True)
    else:
        output_path = Path.cwd()

    skill_filename = output_path / f"{skill_name}.skill"

    # Create the .skill file (zip format)
    try:
        with zipfile.ZipFile(skill_filename, 'w', zipfile.ZIP_DEFLATED) as zipf:
            # Walk through the skill directory, excluding build artifacts
            for file_path in skill_path.rglob('*'):
                if not file_path.is_file():
                    continue
                arcname = file_path.relative_to(skill_path.parent)
                if should_exclude(arcname):
                    print(f"  Skipped: {arcname}")
                    continue
                zipf.write(file_path, arcname)
                print(f"  Added: {arcname}")

        print(f"\n✅ Successfully packaged skill to: {skill_filename}")
        return skill_filename

    except Exception as e:
        print(f"❌ Error creating .skill file: {e}")
        return None


def main():
    if len(sys.argv) < 2:
        print("Usage: python utils/package_skill.py <path/to/skill-folder> [output-directory]")
        print("\nExample:")
        print("  python utils/package_skill.py skills/public/my-skill")
        print("  python utils/package_skill.py skills/public/my-skill ./dist")
        sys.exit(1)

    skill_path = sys.argv[1]
    output_dir = sys.argv[2] if len(sys.argv) > 2 else None

    print(f"📦 Packaging skill: {skill_path}")
    if output_dir:
        print(f"   Output directory: {output_dir}")
    print()

    result = package_skill(skill_path, output_dir)

    if result:
        sys.exit(0)
    else:
        sys.exit(1)


if __name__ == "__main__":
    main()

FILE:scripts/quick_validate.py
#!/usr/bin/env python3
"""
Quick validation script for skills - minimal version
"""

import sys
import os
import re
import yaml
from pathlib import Path

def validate_skill(skill_path):
    """Basic validation of a skill"""
    skill_path = Path(skill_path)

    # Check SKILL.md exists
    skill_md = skill_path / 'SKILL.md'
    if not skill_md.exists():
        return False, "SKILL.md not found"

    # Read and validate frontmatter
    content = skill_md.read_text()
    if not content.startswith('---'):
        return False, "No YAML frontmatter found"

    # Extract frontmatter
    match = re.match(r'^---\n(.*?)\n---', content, re.DOTALL)
    if not match:
        return False, "Invalid frontmatter format"

    frontmatter_text = match.group(1)

    # Parse YAML frontmatter
    try:
        frontmatter = yaml.safe_load(frontmatter_text)
        if not isinstance(frontmatter, dict):
            return False, "Frontmatter must be a YAML dictionary"
    except yaml.YAMLError as e:
        return False, f"Invalid YAML in frontmatter: {e}"

    # Define allowed properties
    ALLOWED_PROPERTIES = {'name', 'description', 'license', 'allowed-tools', 'metadata', 'compatibility'}

    # Check for unexpected properties (excluding nested keys under metadata)
    unexpected_keys = set(frontmatter.keys()) - ALLOWED_PROPERTIES
    if unexpected_keys:
        return False, (
            f"Unexpected key(s) in SKILL.md frontmatter: {', '.join(sorted(unexpected_keys))}. "
            f"Allowed properties are: {', '.join(sorted(ALLOWED_PROPERTIES))}"
        )

    # Check required fields
    if 'name' not in frontmatter:
        return False, "Missing 'name' in frontmatter"
    if 'description' not in frontmatter:
        return False, "Missing 'description' in frontmatter"

    # Extract name for validation
    name = frontmatter.get('name', '')
    if not isinstance(name, str):
        return False, f"Name must be a string, got {type(name).__name__}"
    name = name.strip()
    if name:
        # Check naming convention (kebab-case: lowercase with hyphens)
        if not re.match(r'^[a-z0-9-]+$', name):
            return False, f"Name '{name}' should be kebab-case (lowercase letters, digits, and hyphens only)"
        if name.startswith('-') or name.endswith('-') or '--' in name:
            return False, f"Name '{name}' cannot start/end with hyphen or contain consecutive hyphens"
        # Check name length (max 64 characters per spec)
        if len(name) > 64:
            return False, f"Name is too long ({len(name)} characters). Maximum is 64 characters."

    # Extract and validate description
    description = frontmatter.get('description', '')
    if not isinstance(description, str):
        return False, f"Description must be a string, got {type(description).__name__}"
    description = description.strip()
    if description:
        # Check for angle brackets
        if '<' in description or '>' in description:
            return False, "Description cannot contain angle brackets (< or >)"
        # Check description length (max 1024 characters per spec)
        if len(description) > 1024:
            return False, f"Description is too long ({len(description)} characters). Maximum is 1024 characters."

    # Validate compatibility field if present (optional)
    compatibility = frontmatter.get('compatibility', '')
    if compatibility:
        if not isinstance(compatibility, str):
            return False, f"Compatibility must be a string, got {type(compatibility).__name__}"
        if len(compatibility) > 500:
            return False, f"Compatibility is too long ({len(compatibility)} characters). Maximum is 500 characters."

    return True, "Skill is valid!"

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python quick_validate.py <skill_directory>")
        sys.exit(1)
    
    valid, message = validate_skill(sys.argv[1])
    print(message)
    sys.exit(0 if valid else 1)
FILE:scripts/run_eval.py
#!/usr/bin/env python3
"""Run trigger evaluation for a skill description.

Tests whether a skill's description causes Claude to trigger (read the skill)
for a set of queries. Outputs results as JSON.
"""

import argparse
import json
import os
import select
import subprocess
import sys
import time
import uuid
from concurrent.futures import ProcessPoolExecutor, as_completed
from pathlib import Path

from scripts.utils import parse_skill_md


def find_project_root() -> Path:
    """Find the project root by walking up from cwd looking for .claude/.

    Mimics how Claude Code discovers its project root, so the command file
    we create ends up where claude -p will look for it.
    """
    current = Path.cwd()
    for parent in [current, *current.parents]:
        if (parent / ".claude").is_dir():
            return parent
    return current


def run_single_query(
    query: str,
    skill_name: str,
    skill_description: str,
    timeout: int,
    project_root: str,
    model: str | None = None,
) -> bool:
    """Run a single query and return whether the skill was triggered.

    Creates a command file in .claude/commands/ so it appears in Claude's
    available_skills list, then runs `claude -p` with the raw query.
    Uses --include-partial-messages to detect triggering early from
    stream events (content_block_start) rather than waiting for the
    full assistant message, which only arrives after tool execution.
    """
    unique_id = uuid.uuid4().hex[:8]
    clean_name = f"{skill_name}-skill-{unique_id}"
    project_commands_dir = Path(project_root) / ".claude" / "commands"
    command_file = project_commands_dir / f"{clean_name}.md"

    try:
        project_commands_dir.mkdir(parents=True, exist_ok=True)
        # Use YAML block scalar to avoid breaking on quotes in description
        indented_desc = "\n  ".join(skill_description.split("\n"))
        command_content = (
            f"---\n"
            f"description: |\n"
            f"  {indented_desc}\n"
            f"---\n\n"
            f"# {skill_name}\n\n"
            f"This skill handles: {skill_description}\n"
        )
        command_file.write_text(command_content)

        cmd = [
            "claude",
            "-p", query,
            "--output-format", "stream-json",
            "--verbose",
            "--include-partial-messages",
        ]
        if model:
            cmd.extend(["--model", model])

        # Remove CLAUDECODE env var to allow nesting claude -p inside a
        # Claude Code session. The guard is for interactive terminal conflicts;
        # programmatic subprocess usage is safe.
        env = {k: v for k, v in os.environ.items() if k != "CLAUDECODE"}

        process = subprocess.Popen(
            cmd,
            stdout=subprocess.PIPE,
            stderr=subprocess.DEVNULL,
            cwd=project_root,
            env=env,
        )

        triggered = False
        start_time = time.time()
        buffer = ""
        # Track state for stream event detection
        pending_tool_name = None
        accumulated_json = ""

        try:
            while time.time() - start_time < timeout:
                if process.poll() is not None:
                    remaining = process.stdout.read()
                    if remaining:
                        buffer += remaining.decode("utf-8", errors="replace")
                    break

                ready, _, _ = select.select([process.stdout], [], [], 1.0)
                if not ready:
                    continue

                chunk = os.read(process.stdout.fileno(), 8192)
                if not chunk:
                    break
                buffer += chunk.decode("utf-8", errors="replace")

                while "\n" in buffer:
                    line, buffer = buffer.split("\n", 1)
                    line = line.strip()
                    if not line:
                        continue

                    try:
                        event = json.loads(line)
                    except json.JSONDecodeError:
                        continue

                    # Early detection via stream events
                    if event.get("type") == "stream_event":
                        se = event.get("event", {})
                        se_type = se.get("type", "")

                        if se_type == "content_block_start":
                            cb = se.get("content_block", {})
                            if cb.get("type") == "tool_use":
                                tool_name = cb.get("name", "")
                                if tool_name in ("Skill", "Read"):
                                    pending_tool_name = tool_name
                                    accumulated_json = ""
                                else:
                                    return False

                        elif se_type == "content_block_delta" and pending_tool_name:
                            delta = se.get("delta", {})
                            if delta.get("type") == "input_json_delta":
                                accumulated_json += delta.get("partial_json", "")
                                if clean_name in accumulated_json:
                                    return True

                        elif se_type in ("content_block_stop", "message_stop"):
                            if pending_tool_name:
                                return clean_name in accumulated_json
                            if se_type == "message_stop":
                                return False

                    # Fallback: full assistant message
                    elif event.get("type") == "assistant":
                        message = event.get("message", {})
                        for content_item in message.get("content", []):
                            if content_item.get("type") != "tool_use":
                                continue
                            tool_name = content_item.get("name", "")
                            tool_input = content_item.get("input", {})
                            if tool_name == "Skill" and clean_name in tool_input.get("skill", ""):
                                triggered = True
                            elif tool_name == "Read" and clean_name in tool_input.get("file_path", ""):
                                triggered = True
                            return triggered

                    elif event.get("type") == "result":
                        return triggered
        finally:
            # Clean up process on any exit path (return, exception, timeout)
            if process.poll() is None:
                process.kill()
                process.wait()

        return triggered
    finally:
        if command_file.exists():
            command_file.unlink()


def run_eval(
    eval_set: list[dict],
    skill_name: str,
    description: str,
    num_workers: int,
    timeout: int,
    project_root: Path,
    runs_per_query: int = 1,
    trigger_threshold: float = 0.5,
    model: str | None = None,
) -> dict:
    """Run the full eval set and return results."""
    results = []

    with ProcessPoolExecutor(max_workers=num_workers) as executor:
        future_to_info = {}
        for item in eval_set:
            for run_idx in range(runs_per_query):
                future = executor.submit(
                    run_single_query,
                    item["query"],
                    skill_name,
                    description,
                    timeout,
                    str(project_root),
                    model,
                )
                future_to_info[future] = (item, run_idx)

        query_triggers: dict[str, list[bool]] = {}
        query_items: dict[str, dict] = {}
        for future in as_completed(future_to_info):
            item, _ = future_to_info[future]
            query = item["query"]
            query_items[query] = item
            if query not in query_triggers:
                query_triggers[query] = []
            try:
                query_triggers[query].append(future.result())
            except Exception as e:
                print(f"Warning: query failed: {e}", file=sys.stderr)
                query_triggers[query].append(False)

    for query, triggers in query_triggers.items():
        item = query_items[query]
        trigger_rate = sum(triggers) / len(triggers)
        should_trigger = item["should_trigger"]
        if should_trigger:
            did_pass = trigger_rate >= trigger_threshold
        else:
            did_pass = trigger_rate < trigger_threshold
        results.append({
            "query": query,
            "should_trigger": should_trigger,
            "trigger_rate": trigger_rate,
            "triggers": sum(triggers),
            "runs": len(triggers),
            "pass": did_pass,
        })

    passed = sum(1 for r in results if r["pass"])
    total = len(results)

    return {
        "skill_name": skill_name,
        "description": description,
        "results": results,
        "summary": {
            "total": total,
            "passed": passed,
            "failed": total - passed,
        },
    }


def main():
    parser = argparse.ArgumentParser(description="Run trigger evaluation for a skill description")
    parser.add_argument("--eval-set", required=True, help="Path to eval set JSON file")
    parser.add_argument("--skill-path", required=True, help="Path to skill directory")
    parser.add_argument("--description", default=None, help="Override description to test")
    parser.add_argument("--num-workers", type=int, default=10, help="Number of parallel workers")
    parser.add_argument("--timeout", type=int, default=30, help="Timeout per query in seconds")
    parser.add_argument("--runs-per-query", type=int, default=3, help="Number of runs per query")
    parser.add_argument("--trigger-threshold", type=float, default=0.5, help="Trigger rate threshold")
    parser.add_argument("--model", default=None, help="Model to use for claude -p (default: user's configured model)")
    parser.add_argument("--verbose", action="store_true", help="Print progress to stderr")
    args = parser.parse_args()

    eval_set = json.loads(Path(args.eval_set).read_text())
    skill_path = Path(args.skill_path)

    if not (skill_path / "SKILL.md").exists():
        print(f"Error: No SKILL.md found at {skill_path}", file=sys.stderr)
        sys.exit(1)

    name, original_description, content = parse_skill_md(skill_path)
    description = args.description or original_description
    project_root = find_project_root()

    if args.verbose:
        print(f"Evaluating: {description}", file=sys.stderr)

    output = run_eval(
        eval_set=eval_set,
        skill_name=name,
        description=description,
        num_workers=args.num_workers,
        timeout=args.timeout,
        project_root=project_root,
        runs_per_query=args.runs_per_query,
        trigger_threshold=args.trigger_threshold,
        model=args.model,
    )

    if args.verbose:
        summary = output["summary"]
        print(f"Results: {summary['passed']}/{summary['total']} passed", file=sys.stderr)
        for r in output["results"]:
            status = "PASS" if r["pass"] else "FAIL"
            rate_str = f"{r['triggers']}/{r['runs']}"
            print(f"  [{status}] rate={rate_str} expected={r['should_trigger']}: {r['query'][:70]}", file=sys.stderr)

    print(json.dumps(output, indent=2))


if __name__ == "__main__":
    main()

FILE:scripts/run_loop.py
#!/usr/bin/env python3
"""Run the eval + improve loop until all pass or max iterations reached.

Combines run_eval.py and improve_description.py in a loop, tracking history
and returning the best description found. Supports train/test split to prevent
overfitting.
"""

import argparse
import json
import random
import sys
import tempfile
import time
import webbrowser
from pathlib import Path

from scripts.generate_report import generate_html
from scripts.improve_description import improve_description
from scripts.run_eval import find_project_root, run_eval
from scripts.utils import parse_skill_md


def split_eval_set(eval_set: list[dict], holdout: float, seed: int = 42) -> tuple[list[dict], list[dict]]:
    """Split eval set into train and test sets, stratified by should_trigger."""
    random.seed(seed)

    # Separate by should_trigger
    trigger = [e for e in eval_set if e["should_trigger"]]
    no_trigger = [e for e in eval_set if not e["should_trigger"]]

    # Shuffle each group
    random.shuffle(trigger)
    random.shuffle(no_trigger)

    # Calculate split points
    n_trigger_test = max(1, int(len(trigger) * holdout))
    n_no_trigger_test = max(1, int(len(no_trigger) * holdout))

    # Split
    test_set = trigger[:n_trigger_test] + no_trigger[:n_no_trigger_test]
    train_set = trigger[n_trigger_test:] + no_trigger[n_no_trigger_test:]

    return train_set, test_set


def run_loop(
    eval_set: list[dict],
    skill_path: Path,
    description_override: str | None,
    num_workers: int,
    timeout: int,
    max_iterations: int,
    runs_per_query: int,
    trigger_threshold: float,
    holdout: float,
    model: str,
    verbose: bool,
    live_report_path: Path | None = None,
    log_dir: Path | None = None,
) -> dict:
    """Run the eval + improvement loop."""
    project_root = find_project_root()
    name, original_description, content = parse_skill_md(skill_path)
    current_description = description_override or original_description

    # Split into train/test if holdout > 0
    if holdout > 0:
        train_set, test_set = split_eval_set(eval_set, holdout)
        if verbose:
            print(f"Split: {len(train_set)} train, {len(test_set)} test (holdout={holdout})", file=sys.stderr)
    else:
        train_set = eval_set
        test_set = []

    history = []
    exit_reason = "unknown"

    for iteration in range(1, max_iterations + 1):
        if verbose:
            print(f"\n{'='*60}", file=sys.stderr)
            print(f"Iteration {iteration}/{max_iterations}", file=sys.stderr)
            print(f"Description: {current_description}", file=sys.stderr)
            print(f"{'='*60}", file=sys.stderr)

        # Evaluate train + test together in one batch for parallelism
        all_queries = train_set + test_set
        t0 = time.time()
        all_results = run_eval(
            eval_set=all_queries,
            skill_name=name,
            description=current_description,
            num_workers=num_workers,
            timeout=timeout,
            project_root=project_root,
            runs_per_query=runs_per_query,
            trigger_threshold=trigger_threshold,
            model=model,
        )
        eval_elapsed = time.time() - t0

        # Split results back into train/test by matching queries
        train_queries_set = {q["query"] for q in train_set}
        train_result_list = [r for r in all_results["results"] if r["query"] in train_queries_set]
        test_result_list = [r for r in all_results["results"] if r["query"] not in train_queries_set]

        train_passed = sum(1 for r in train_result_list if r["pass"])
        train_total = len(train_result_list)
        train_summary = {"passed": train_passed, "failed": train_total - train_passed, "total": train_total}
        train_results = {"results": train_result_list, "summary": train_summary}

        if test_set:
            test_passed = sum(1 for r in test_result_list if r["pass"])
            test_total = len(test_result_list)
            test_summary = {"passed": test_passed, "failed": test_total - test_passed, "total": test_total}
            test_results = {"results": test_result_list, "summary": test_summary}
        else:
            test_results = None
            test_summary = None

        history.append({
            "iteration": iteration,
            "description": current_description,
            "train_passed": train_summary["passed"],
            "train_failed": train_summary["failed"],
            "train_total": train_summary["total"],
            "train_results": train_results["results"],
            "test_passed": test_summary["passed"] if test_summary else None,
            "test_failed": test_summary["failed"] if test_summary else None,
            "test_total": test_summary["total"] if test_summary else None,
            "test_results": test_results["results"] if test_results else None,
            # For backward compat with report generator
            "passed": train_summary["passed"],
            "failed": train_summary["failed"],
            "total": train_summary["total"],
            "results": train_results["results"],
        })

        # Write live report if path provided
        if live_report_path:
            partial_output = {
                "original_description": original_description,
                "best_description": current_description,
                "best_score": "in progress",
                "iterations_run": len(history),
                "holdout": holdout,
                "train_size": len(train_set),
                "test_size": len(test_set),
                "history": history,
            }
            live_report_path.write_text(generate_html(partial_output, auto_refresh=True, skill_name=name))

        if verbose:
            def print_eval_stats(label, results, elapsed):
                pos = [r for r in results if r["should_trigger"]]
                neg = [r for r in results if not r["should_trigger"]]
                tp = sum(r["triggers"] for r in pos)
                pos_runs = sum(r["runs"] for r in pos)
                fn = pos_runs - tp
                fp = sum(r["triggers"] for r in neg)
                neg_runs = sum(r["runs"] for r in neg)
                tn = neg_runs - fp
                total = tp + tn + fp + fn
                precision = tp / (tp + fp) if (tp + fp) > 0 else 1.0
                recall = tp / (tp + fn) if (tp + fn) > 0 else 1.0
                accuracy = (tp + tn) / total if total > 0 else 0.0
                print(f"{label}: {tp+tn}/{total} correct, precision={precision:.0%} recall={recall:.0%} accuracy={accuracy:.0%} ({elapsed:.1f}s)", file=sys.stderr)
                for r in results:
                    status = "PASS" if r["pass"] else "FAIL"
                    rate_str = f"{r['triggers']}/{r['runs']}"
                    print(f"  [{status}] rate={rate_str} expected={r['should_trigger']}: {r['query'][:60]}", file=sys.stderr)

            print_eval_stats("Train", train_results["results"], eval_elapsed)
            if test_summary:
                print_eval_stats("Test ", test_results["results"], 0)

        if train_summary["failed"] == 0:
            exit_reason = f"all_passed (iteration {iteration})"
            if verbose:
                print(f"\nAll train queries passed on iteration {iteration}!", file=sys.stderr)
            break

        if iteration == max_iterations:
            exit_reason = f"max_iterations ({max_iterations})"
            if verbose:
                print(f"\nMax iterations reached ({max_iterations}).", file=sys.stderr)
            break

        # Improve the description based on train results
        if verbose:
            print(f"\nImproving description...", file=sys.stderr)

        t0 = time.time()
        # Strip test scores from history so improvement model can't see them
        blinded_history = [
            {k: v for k, v in h.items() if not k.startswith("test_")}
            for h in history
        ]
        new_description = improve_description(
            skill_name=name,
            skill_content=content,
            current_description=current_description,
            eval_results=train_results,
            history=blinded_history,
            model=model,
            log_dir=log_dir,
            iteration=iteration,
        )
        improve_elapsed = time.time() - t0

        if verbose:
            print(f"Proposed ({improve_elapsed:.1f}s): {new_description}", file=sys.stderr)

        current_description = new_description

    # Find the best iteration by TEST score (or train if no test set)
    if test_set:
        best = max(history, key=lambda h: h["test_passed"] or 0)
        best_score = f"{best['test_passed']}/{best['test_total']}"
    else:
        best = max(history, key=lambda h: h["train_passed"])
        best_score = f"{best['train_passed']}/{best['train_total']}"

    if verbose:
        print(f"\nExit reason: {exit_reason}", file=sys.stderr)
        print(f"Best score: {best_score} (iteration {best['iteration']})", file=sys.stderr)

    return {
        "exit_reason": exit_reason,
        "original_description": original_description,
        "best_description": best["description"],
        "best_score": best_score,
        "best_train_score": f"{best['train_passed']}/{best['train_total']}",
        "best_test_score": f"{best['test_passed']}/{best['test_total']}" if test_set else None,
        "final_description": current_description,
        "iterations_run": len(history),
        "holdout": holdout,
        "train_size": len(train_set),
        "test_size": len(test_set),
        "history": history,
    }


def main():
    parser = argparse.ArgumentParser(description="Run eval + improve loop")
    parser.add_argument("--eval-set", required=True, help="Path to eval set JSON file")
    parser.add_argument("--skill-path", required=True, help="Path to skill directory")
    parser.add_argument("--description", default=None, help="Override starting description")
    parser.add_argument("--num-workers", type=int, default=10, help="Number of parallel workers")
    parser.add_argument("--timeout", type=int, default=30, help="Timeout per query in seconds")
    parser.add_argument("--max-iterations", type=int, default=5, help="Max improvement iterations")
    parser.add_argument("--runs-per-query", type=int, default=3, help="Number of runs per query")
    parser.add_argument("--trigger-threshold", type=float, default=0.5, help="Trigger rate threshold")
    parser.add_argument("--holdout", type=float, default=0.4, help="Fraction of eval set to hold out for testing (0 to disable)")
    parser.add_argument("--model", required=True, help="Model for improvement")
    parser.add_argument("--verbose", action="store_true", help="Print progress to stderr")
    parser.add_argument("--report", default="auto", help="Generate HTML report at this path (default: 'auto' for temp file, 'none' to disable)")
    parser.add_argument("--results-dir", default=None, help="Save all outputs (results.json, report.html, log.txt) to a timestamped subdirectory here")
    args = parser.parse_args()

    eval_set = json.loads(Path(args.eval_set).read_text())
    skill_path = Path(args.skill_path)

    if not (skill_path / "SKILL.md").exists():
        print(f"Error: No SKILL.md found at {skill_path}", file=sys.stderr)
        sys.exit(1)

    name, _, _ = parse_skill_md(skill_path)

    # Set up live report path
    if args.report != "none":
        if args.report == "auto":
            timestamp = time.strftime("%Y%m%d_%H%M%S")
            live_report_path = Path(tempfile.gettempdir()) / f"skill_description_report_{skill_path.name}_{timestamp}.html"
        else:
            live_report_path = Path(args.report)
        # Open the report immediately so the user can watch
        live_report_path.write_text("<html><body><h1>Starting optimization loop...</h1><meta http-equiv='refresh' content='5'></body></html>")
        webbrowser.open(str(live_report_path))
    else:
        live_report_path = None

    # Determine output directory (create before run_loop so logs can be written)
    if args.results_dir:
        timestamp = time.strftime("%Y-%m-%d_%H%M%S")
        results_dir = Path(args.results_dir) / timestamp
        results_dir.mkdir(parents=True, exist_ok=True)
    else:
        results_dir = None

    log_dir = results_dir / "logs" if results_dir else None

    output = run_loop(
        eval_set=eval_set,
        skill_path=skill_path,
        description_override=args.description,
        num_workers=args.num_workers,
        timeout=args.timeout,
        max_iterations=args.max_iterations,
        runs_per_query=args.runs_per_query,
        trigger_threshold=args.trigger_threshold,
        holdout=args.holdout,
        model=args.model,
        verbose=args.verbose,
        live_report_path=live_report_path,
        log_dir=log_dir,
    )

    # Save JSON output
    json_output = json.dumps(output, indent=2)
    print(json_output)
    if results_dir:
        (results_dir / "results.json").write_text(json_output)

    # Write final HTML report (without auto-refresh)
    if live_report_path:
        live_report_path.write_text(generate_html(output, auto_refresh=False, skill_name=name))
        print(f"\nReport: {live_report_path}", file=sys.stderr)

    if results_dir and live_report_path:
        (results_dir / "report.html").write_text(generate_html(output, auto_refresh=False, skill_name=name))

    if results_dir:
        print(f"Results saved to: {results_dir}", file=sys.stderr)


if __name__ == "__main__":
    main()

FILE:scripts/utils.py
"""Shared utilities for skill-creator scripts."""

from pathlib import Path



def parse_skill_md(skill_path: Path) -> tuple[str, str, str]:
    """Parse a SKILL.md file, returning (name, description, full_content)."""
    content = (skill_path / "SKILL.md").read_text()
    lines = content.split("\n")

    if lines[0].strip() != "---":
        raise ValueError("SKILL.md missing frontmatter (no opening ---)")

    end_idx = None
    for i, line in enumerate(lines[1:], start=1):
        if line.strip() == "---":
            end_idx = i
            break

    if end_idx is None:
        raise ValueError("SKILL.md missing frontmatter (no closing ---)")

    name = ""
    description = ""
    frontmatter_lines = lines[1:end_idx]
    i = 0
    while i < len(frontmatter_lines):
        line = frontmatter_lines[i]
        if line.startswith("name:"):
            name = line[len("name:"):].strip().strip('"').strip("'")
        elif line.startswith("description:"):
            value = line[len("description:"):].strip()
            # Handle YAML multiline indicators (>, |, >-, |-)
            if value in (">", "|", ">-", "|-"):
                continuation_lines: list[str] = []
                i += 1
                while i < len(frontmatter_lines) and (frontmatter_lines[i].startswith("  ") or frontmatter_lines[i].startswith("\t")):
                    continuation_lines.append(frontmatter_lines[i].strip())
                    i += 1
                description = " ".join(continuation_lines)
                continue
            else:
                description = value.strip('"').strip("'")
        i += 1

    return name, description, content

FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/skill-creator
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: mcp-builder
description: Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).
license: Complete terms in LICENSE.txt
---

# MCP Server Development Guide

## Overview

Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks.

---

# Process

## 🚀 High-Level Workflow

Creating a high-quality MCP server involves four main phases:

### Phase 1: Deep Research and Planning

#### 1.1 Understand Modern MCP Design

**API Coverage vs. Workflow Tools:**
Balance comprehensive API endpoint coverage with specialized workflow tools. Workflow tools can be more convenient for specific tasks, while comprehensive coverage gives agents flexibility to compose operations. Performance varies by client—some clients benefit from code execution that combines basic tools, while others work better with higher-level workflows. When uncertain, prioritize comprehensive API coverage.

**Tool Naming and Discoverability:**
Clear, descriptive tool names help agents find the right tools quickly. Use consistent prefixes (e.g., `github_create_issue`, `github_list_repos`) and action-oriented naming.

**Context Management:**
Agents benefit from concise tool descriptions and the ability to filter/paginate results. Design tools that return focused, relevant data. Some clients support code execution which can help agents filter and process data efficiently.

**Actionable Error Messages:**
Error messages should guide agents toward solutions with specific suggestions and next steps.

#### 1.2 Study MCP Protocol Documentation

**Navigate the MCP specification:**

Start with the sitemap to find relevant pages: `https://modelcontextprotocol.io/sitemap.xml`

Then fetch specific pages with `.md` suffix for markdown format (e.g., `https://modelcontextprotocol.io/specification/draft.md`).

Key pages to review:
- Specification overview and architecture
- Transport mechanisms (streamable HTTP, stdio)
- Tool, resource, and prompt definitions

#### 1.3 Study Framework Documentation

**Recommended stack:**
- **Language**: TypeScript (high-quality SDK support and good compatibility in many execution environments e.g. MCPB. Plus AI models are good at generating TypeScript code, benefiting from its broad usage, static typing and good linting tools)
- **Transport**: Streamable HTTP for remote servers, using stateless JSON (simpler to scale and maintain, as opposed to stateful sessions and streaming responses). stdio for local servers.

**Load framework documentation:**

- **MCP Best Practices**: [📋 View Best Practices](./reference/mcp_best_practices.md) - Core guidelines

**For TypeScript (recommended):**
- **TypeScript SDK**: Use WebFetch to load `https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md`
- [⚡ TypeScript Guide](./reference/node_mcp_server.md) - TypeScript patterns and examples

**For Python:**
- **Python SDK**: Use WebFetch to load `https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md`
- [🐍 Python Guide](./reference/python_mcp_server.md) - Python patterns and examples

#### 1.4 Plan Your Implementation

**Understand the API:**
Review the service's API documentation to identify key endpoints, authentication requirements, and data models. Use web search and WebFetch as needed.

**Tool Selection:**
Prioritize comprehensive API coverage. List endpoints to implement, starting with the most common operations.

---

### Phase 2: Implementation

#### 2.1 Set Up Project Structure

See language-specific guides for project setup:
- [⚡ TypeScript Guide](./reference/node_mcp_server.md) - Project structure, package.json, tsconfig.json
- [🐍 Python Guide](./reference/python_mcp_server.md) - Module organization, dependencies

#### 2.2 Implement Core Infrastructure

Create shared utilities:
- API client with authentication
- Error handling helpers
- Response formatting (JSON/Markdown)
- Pagination support

#### 2.3 Implement Tools

For each tool:

**Input Schema:**
- Use Zod (TypeScript) or Pydantic (Python)
- Include constraints and clear descriptions
- Add examples in field descriptions

**Output Schema:**
- Define `outputSchema` where possible for structured data
- Use `structuredContent` in tool responses (TypeScript SDK feature)
- Helps clients understand and process tool outputs

**Tool Description:**
- Concise summary of functionality
- Parameter descriptions
- Return type schema

**Implementation:**
- Async/await for I/O operations
- Proper error handling with actionable messages
- Support pagination where applicable
- Return both text content and structured data when using modern SDKs

**Annotations:**
- `readOnlyHint`: true/false
- `destructiveHint`: true/false
- `idempotentHint`: true/false
- `openWorldHint`: true/false

---

### Phase 3: Review and Test

#### 3.1 Code Quality

Review for:
- No duplicated code (DRY principle)
- Consistent error handling
- Full type coverage
- Clear tool descriptions

#### 3.2 Build and Test

**TypeScript:**
- Run `npm run build` to verify compilation
- Test with MCP Inspector: `npx @modelcontextprotocol/inspector`

**Python:**
- Verify syntax: `python -m py_compile your_server.py`
- Test with MCP Inspector

See language-specific guides for detailed testing approaches and quality checklists.

---

### Phase 4: Create Evaluations

After implementing your MCP server, create comprehensive evaluations to test its effectiveness.

**Load [✅ Evaluation Guide](./reference/evaluation.md) for complete evaluation guidelines.**

#### 4.1 Understand Evaluation Purpose

Use evaluations to test whether LLMs can effectively use your MCP server to answer realistic, complex questions.

#### 4.2 Create 10 Evaluation Questions

To create effective evaluations, follow the process outlined in the evaluation guide:

1. **Tool Inspection**: List available tools and understand their capabilities
2. **Content Exploration**: Use READ-ONLY operations to explore available data
3. **Question Generation**: Create 10 complex, realistic questions
4. **Answer Verification**: Solve each question yourself to verify answers

#### 4.3 Evaluation Requirements

Ensure each question is:
- **Independent**: Not dependent on other questions
- **Read-only**: Only non-destructive operations required
- **Complex**: Requiring multiple tool calls and deep exploration
- **Realistic**: Based on real use cases humans would care about
- **Verifiable**: Single, clear answer that can be verified by string comparison
- **Stable**: Answer won't change over time

#### 4.4 Output Format

Create an XML file with this structure:

```xml
<evaluation>
  <qa_pair>
    <question>Find discussions about AI model launches with animal codenames. One model needed a specific safety designation that uses the format ASL-X. What number X was being determined for the model named after a spotted wild cat?</question>
    <answer>3</answer>
  </qa_pair>
<!-- More qa_pairs... -->
</evaluation>
```

---

# Reference Files

## 📚 Documentation Library

Load these resources as needed during development:

### Core MCP Documentation (Load First)
- **MCP Protocol**: Start with sitemap at `https://modelcontextprotocol.io/sitemap.xml`, then fetch specific pages with `.md` suffix
- [📋 MCP Best Practices](./reference/mcp_best_practices.md) - Universal MCP guidelines including:
  - Server and tool naming conventions
  - Response format guidelines (JSON vs Markdown)
  - Pagination best practices
  - Transport selection (streamable HTTP vs stdio)
  - Security and error handling standards

### SDK Documentation (Load During Phase 1/2)
- **Python SDK**: Fetch from `https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md`
- **TypeScript SDK**: Fetch from `https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md`

### Language-Specific Implementation Guides (Load During Phase 2)
- [🐍 Python Implementation Guide](./reference/python_mcp_server.md) - Complete Python/FastMCP guide with:
  - Server initialization patterns
  - Pydantic model examples
  - Tool registration with `@mcp.tool`
  - Complete working examples
  - Quality checklist

- [⚡ TypeScript Implementation Guide](./reference/node_mcp_server.md) - Complete TypeScript guide with:
  - Project structure
  - Zod schema patterns
  - Tool registration with `server.registerTool`
  - Complete working examples
  - Quality checklist

### Evaluation Guide (Load During Phase 4)
- [✅ Evaluation Guide](./reference/evaluation.md) - Complete evaluation creation guide with:
  - Question creation guidelines
  - Answer verification strategies
  - XML format specifications
  - Example questions and answers
  - Running an evaluation with the provided scripts

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:reference/evaluation.md
# MCP Server Evaluation Guide

## Overview

This document provides guidance on creating comprehensive evaluations for MCP servers. Evaluations test whether LLMs can effectively use your MCP server to answer realistic, complex questions using only the tools provided.

---

## Quick Reference

### Evaluation Requirements
- Create 10 human-readable questions
- Questions must be READ-ONLY, INDEPENDENT, NON-DESTRUCTIVE
- Each question requires multiple tool calls (potentially dozens)
- Answers must be single, verifiable values
- Answers must be STABLE (won't change over time)

### Output Format
```xml
<evaluation>
   <qa_pair>
      <question>Your question here</question>
      <answer>Single verifiable answer</answer>
   </qa_pair>
</evaluation>
```

---

## Purpose of Evaluations

The measure of quality of an MCP server is NOT how well or comprehensively the server implements tools, but how well these implementations (input/output schemas, docstrings/descriptions, functionality) enable LLMs with no other context and access ONLY to the MCP servers to answer realistic and difficult questions.

## Evaluation Overview

Create 10 human-readable questions requiring ONLY READ-ONLY, INDEPENDENT, NON-DESTRUCTIVE, and IDEMPOTENT operations to answer. Each question should be:
- Realistic
- Clear and concise
- Unambiguous
- Complex, requiring potentially dozens of tool calls or steps
- Answerable with a single, verifiable value that you identify in advance

## Question Guidelines

### Core Requirements

1. **Questions MUST be independent**
   - Each question should NOT depend on the answer to any other question
   - Should not assume prior write operations from processing another question

2. **Questions MUST require ONLY NON-DESTRUCTIVE AND IDEMPOTENT tool use**
   - Should not instruct or require modifying state to arrive at the correct answer

3. **Questions must be REALISTIC, CLEAR, CONCISE, and COMPLEX**
   - Must require another LLM to use multiple (potentially dozens of) tools or steps to answer

### Complexity and Depth

4. **Questions must require deep exploration**
   - Consider multi-hop questions requiring multiple sub-questions and sequential tool calls
   - Each step should benefit from information found in previous questions

5. **Questions may require extensive paging**
   - May need paging through multiple pages of results
   - May require querying old data (1-2 years out-of-date) to find niche information
   - The questions must be DIFFICULT

6. **Questions must require deep understanding**
   - Rather than surface-level knowledge
   - May pose complex ideas as True/False questions requiring evidence
   - May use multiple-choice format where LLM must search different hypotheses

7. **Questions must not be solvable with straightforward keyword search**
   - Do not include specific keywords from the target content
   - Use synonyms, related concepts, or paraphrases
   - Require multiple searches, analyzing multiple related items, extracting context, then deriving the answer

### Tool Testing

8. **Questions should stress-test tool return values**
   - May elicit tools returning large JSON objects or lists, overwhelming the LLM
   - Should require understanding multiple modalities of data:
     - IDs and names
     - Timestamps and datetimes (months, days, years, seconds)
     - File IDs, names, extensions, and mimetypes
     - URLs, GIDs, etc.
   - Should probe the tool's ability to return all useful forms of data

9. **Questions should MOSTLY reflect real human use cases**
   - The kinds of information retrieval tasks that HUMANS assisted by an LLM would care about

10. **Questions may require dozens of tool calls**
    - This challenges LLMs with limited context
    - Encourages MCP server tools to reduce information returned

11. **Include ambiguous questions**
    - May be ambiguous OR require difficult decisions on which tools to call
    - Force the LLM to potentially make mistakes or misinterpret
    - Ensure that despite AMBIGUITY, there is STILL A SINGLE VERIFIABLE ANSWER

### Stability

12. **Questions must be designed so the answer DOES NOT CHANGE**
    - Do not ask questions that rely on "current state" which is dynamic
    - For example, do not count:
      - Number of reactions to a post
      - Number of replies to a thread
      - Number of members in a channel

13. **DO NOT let the MCP server RESTRICT the kinds of questions you create**
    - Create challenging and complex questions
    - Some may not be solvable with the available MCP server tools
    - Questions may require specific output formats (datetime vs. epoch time, JSON vs. MARKDOWN)
    - Questions may require dozens of tool calls to complete

## Answer Guidelines

### Verification

1. **Answers must be VERIFIABLE via direct string comparison**
   - If the answer can be re-written in many formats, clearly specify the output format in the QUESTION
   - Examples: "Use YYYY/MM/DD.", "Respond True or False.", "Answer A, B, C, or D and nothing else."
   - Answer should be a single VERIFIABLE value such as:
     - User ID, user name, display name, first name, last name
     - Channel ID, channel name
     - Message ID, string
     - URL, title
     - Numerical quantity
     - Timestamp, datetime
     - Boolean (for True/False questions)
     - Email address, phone number
     - File ID, file name, file extension
     - Multiple choice answer
   - Answers must not require special formatting or complex, structured output
   - Answer will be verified using DIRECT STRING COMPARISON

### Readability

2. **Answers should generally prefer HUMAN-READABLE formats**
   - Examples: names, first name, last name, datetime, file name, message string, URL, yes/no, true/false, a/b/c/d
   - Rather than opaque IDs (though IDs are acceptable)
   - The VAST MAJORITY of answers should be human-readable

### Stability

3. **Answers must be STABLE/STATIONARY**
   - Look at old content (e.g., conversations that have ended, projects that have launched, questions answered)
   - Create QUESTIONS based on "closed" concepts that will always return the same answer
   - Questions may ask to consider a fixed time window to insulate from non-stationary answers
   - Rely on context UNLIKELY to change
   - Example: if finding a paper name, be SPECIFIC enough so answer is not confused with papers published later

4. **Answers must be CLEAR and UNAMBIGUOUS**
   - Questions must be designed so there is a single, clear answer
   - Answer can be derived from using the MCP server tools

### Diversity

5. **Answers must be DIVERSE**
   - Answer should be a single VERIFIABLE value in diverse modalities and formats
   - User concept: user ID, user name, display name, first name, last name, email address, phone number
   - Channel concept: channel ID, channel name, channel topic
   - Message concept: message ID, message string, timestamp, month, day, year

6. **Answers must NOT be complex structures**
   - Not a list of values
   - Not a complex object
   - Not a list of IDs or strings
   - Not natural language text
   - UNLESS the answer can be straightforwardly verified using DIRECT STRING COMPARISON
   - And can be realistically reproduced
   - It should be unlikely that an LLM would return the same list in any other order or format

## Evaluation Process

### Step 1: Documentation Inspection

Read the documentation of the target API to understand:
- Available endpoints and functionality
- If ambiguity exists, fetch additional information from the web
- Parallelize this step AS MUCH AS POSSIBLE
- Ensure each subagent is ONLY examining documentation from the file system or on the web

### Step 2: Tool Inspection

List the tools available in the MCP server:
- Inspect the MCP server directly
- Understand input/output schemas, docstrings, and descriptions
- WITHOUT calling the tools themselves at this stage

### Step 3: Developing Understanding

Repeat steps 1 & 2 until you have a good understanding:
- Iterate multiple times
- Think about the kinds of tasks you want to create
- Refine your understanding
- At NO stage should you READ the code of the MCP server implementation itself
- Use your intuition and understanding to create reasonable, realistic, but VERY challenging tasks

### Step 4: Read-Only Content Inspection

After understanding the API and tools, USE the MCP server tools:
- Inspect content using READ-ONLY and NON-DESTRUCTIVE operations ONLY
- Goal: identify specific content (e.g., users, channels, messages, projects, tasks) for creating realistic questions
- Should NOT call any tools that modify state
- Will NOT read the code of the MCP server implementation itself
- Parallelize this step with individual sub-agents pursuing independent explorations
- Ensure each subagent is only performing READ-ONLY, NON-DESTRUCTIVE, and IDEMPOTENT operations
- BE CAREFUL: SOME TOOLS may return LOTS OF DATA which would cause you to run out of CONTEXT
- Make INCREMENTAL, SMALL, AND TARGETED tool calls for exploration
- In all tool call requests, use the `limit` parameter to limit results (<10)
- Use pagination

### Step 5: Task Generation

After inspecting the content, create 10 human-readable questions:
- An LLM should be able to answer these with the MCP server
- Follow all question and answer guidelines above

## Output Format

Each QA pair consists of a question and an answer. The output should be an XML file with this structure:

```xml
<evaluation>
   <qa_pair>
      <question>Find the project created in Q2 2024 with the highest number of completed tasks. What is the project name?</question>
      <answer>Website Redesign</answer>
   </qa_pair>
   <qa_pair>
      <question>Search for issues labeled as "bug" that were closed in March 2024. Which user closed the most issues? Provide their username.</question>
      <answer>sarah_dev</answer>
   </qa_pair>
   <qa_pair>
      <question>Look for pull requests that modified files in the /api directory and were merged between January 1 and January 31, 2024. How many different contributors worked on these PRs?</question>
      <answer>7</answer>
   </qa_pair>
   <qa_pair>
      <question>Find the repository with the most stars that was created before 2023. What is the repository name?</question>
      <answer>data-pipeline</answer>
   </qa_pair>
</evaluation>
```

## Evaluation Examples

### Good Questions

**Example 1: Multi-hop question requiring deep exploration (GitHub MCP)**
```xml
<qa_pair>
   <question>Find the repository that was archived in Q3 2023 and had previously been the most forked project in the organization. What was the primary programming language used in that repository?</question>
   <answer>Python</answer>
</qa_pair>
```

This question is good because:
- Requires multiple searches to find archived repositories
- Needs to identify which had the most forks before archival
- Requires examining repository details for the language
- Answer is a simple, verifiable value
- Based on historical (closed) data that won't change

**Example 2: Requires understanding context without keyword matching (Project Management MCP)**
```xml
<qa_pair>
   <question>Locate the initiative focused on improving customer onboarding that was completed in late 2023. The project lead created a retrospective document after completion. What was the lead's role title at that time?</question>
   <answer>Product Manager</answer>
</qa_pair>
```

This question is good because:
- Doesn't use specific project name ("initiative focused on improving customer onboarding")
- Requires finding completed projects from specific timeframe
- Needs to identify the project lead and their role
- Requires understanding context from retrospective documents
- Answer is human-readable and stable
- Based on completed work (won't change)

**Example 3: Complex aggregation requiring multiple steps (Issue Tracker MCP)**
```xml
<qa_pair>
   <question>Among all bugs reported in January 2024 that were marked as critical priority, which assignee resolved the highest percentage of their assigned bugs within 48 hours? Provide the assignee's username.</question>
   <answer>alex_eng</answer>
</qa_pair>
```

This question is good because:
- Requires filtering bugs by date, priority, and status
- Needs to group by assignee and calculate resolution rates
- Requires understanding timestamps to determine 48-hour windows
- Tests pagination (potentially many bugs to process)
- Answer is a single username
- Based on historical data from specific time period

**Example 4: Requires synthesis across multiple data types (CRM MCP)**
```xml
<qa_pair>
   <question>Find the account that upgraded from the Starter to Enterprise plan in Q4 2023 and had the highest annual contract value. What industry does this account operate in?</question>
   <answer>Healthcare</answer>
</qa_pair>
```

This question is good because:
- Requires understanding subscription tier changes
- Needs to identify upgrade events in specific timeframe
- Requires comparing contract values
- Must access account industry information
- Answer is simple and verifiable
- Based on completed historical transactions

### Poor Questions

**Example 1: Answer changes over time**
```xml
<qa_pair>
   <question>How many open issues are currently assigned to the engineering team?</question>
   <answer>47</answer>
</qa_pair>
```

This question is poor because:
- The answer will change as issues are created, closed, or reassigned
- Not based on stable/stationary data
- Relies on "current state" which is dynamic

**Example 2: Too easy with keyword search**
```xml
<qa_pair>
   <question>Find the pull request with title "Add authentication feature" and tell me who created it.</question>
   <answer>developer123</answer>
</qa_pair>
```

This question is poor because:
- Can be solved with a straightforward keyword search for exact title
- Doesn't require deep exploration or understanding
- No synthesis or analysis needed

**Example 3: Ambiguous answer format**
```xml
<qa_pair>
   <question>List all the repositories that have Python as their primary language.</question>
   <answer>repo1, repo2, repo3, data-pipeline, ml-tools</answer>
</qa_pair>
```

This question is poor because:
- Answer is a list that could be returned in any order
- Difficult to verify with direct string comparison
- LLM might format differently (JSON array, comma-separated, newline-separated)
- Better to ask for a specific aggregate (count) or superlative (most stars)

## Verification Process

After creating evaluations:

1. **Examine the XML file** to understand the schema
2. **Load each task instruction** and in parallel using the MCP server and tools, identify the correct answer by attempting to solve the task YOURSELF
3. **Flag any operations** that require WRITE or DESTRUCTIVE operations
4. **Accumulate all CORRECT answers** and replace any incorrect answers in the document
5. **Remove any `<qa_pair>`** that require WRITE or DESTRUCTIVE operations

Remember to parallelize solving tasks to avoid running out of context, then accumulate all answers and make changes to the file at the end.

## Tips for Creating Quality Evaluations

1. **Think Hard and Plan Ahead** before generating tasks
2. **Parallelize Where Opportunity Arises** to speed up the process and manage context
3. **Focus on Realistic Use Cases** that humans would actually want to accomplish
4. **Create Challenging Questions** that test the limits of the MCP server's capabilities
5. **Ensure Stability** by using historical data and closed concepts
6. **Verify Answers** by solving the questions yourself using the MCP server tools
7. **Iterate and Refine** based on what you learn during the process

---

# Running Evaluations

After creating your evaluation file, you can use the provided evaluation harness to test your MCP server.

## Setup

1. **Install Dependencies**

   ```bash
   pip install -r scripts/requirements.txt
   ```

   Or install manually:
   ```bash
   pip install anthropic mcp
   ```

2. **Set API Key**

   ```bash
   export ANTHROPIC_API_KEY=your_api_key_here
   ```

## Evaluation File Format

Evaluation files use XML format with `<qa_pair>` elements:

```xml
<evaluation>
   <qa_pair>
      <question>Find the project created in Q2 2024 with the highest number of completed tasks. What is the project name?</question>
      <answer>Website Redesign</answer>
   </qa_pair>
   <qa_pair>
      <question>Search for issues labeled as "bug" that were closed in March 2024. Which user closed the most issues? Provide their username.</question>
      <answer>sarah_dev</answer>
   </qa_pair>
</evaluation>
```

## Running Evaluations

The evaluation script (`scripts/evaluation.py`) supports three transport types:

**Important:**
- **stdio transport**: The evaluation script automatically launches and manages the MCP server process for you. Do not run the server manually.
- **sse/http transports**: You must start the MCP server separately before running the evaluation. The script connects to the already-running server at the specified URL.

### 1. Local STDIO Server

For locally-run MCP servers (script launches the server automatically):

```bash
python scripts/evaluation.py \
  -t stdio \
  -c python \
  -a my_mcp_server.py \
  evaluation.xml
```

With environment variables:
```bash
python scripts/evaluation.py \
  -t stdio \
  -c python \
  -a my_mcp_server.py \
  -e API_KEY=abc123 \
  -e DEBUG=true \
  evaluation.xml
```

### 2. Server-Sent Events (SSE)

For SSE-based MCP servers (you must start the server first):

```bash
python scripts/evaluation.py \
  -t sse \
  -u https://example.com/mcp \
  -H "Authorization: Bearer token123" \
  -H "X-Custom-Header: value" \
  evaluation.xml
```

### 3. HTTP (Streamable HTTP)

For HTTP-based MCP servers (you must start the server first):

```bash
python scripts/evaluation.py \
  -t http \
  -u https://example.com/mcp \
  -H "Authorization: Bearer token123" \
  evaluation.xml
```

## Command-Line Options

```
usage: evaluation.py [-h] [-t {stdio,sse,http}] [-m MODEL] [-c COMMAND]
                     [-a ARGS [ARGS ...]] [-e ENV [ENV ...]] [-u URL]
                     [-H HEADERS [HEADERS ...]] [-o OUTPUT]
                     eval_file

positional arguments:
  eval_file             Path to evaluation XML file

optional arguments:
  -h, --help            Show help message
  -t, --transport       Transport type: stdio, sse, or http (default: stdio)
  -m, --model           Claude model to use (default: claude-3-7-sonnet-20250219)
  -o, --output          Output file for report (default: print to stdout)

stdio options:
  -c, --command         Command to run MCP server (e.g., python, node)
  -a, --args            Arguments for the command (e.g., server.py)
  -e, --env             Environment variables in KEY=VALUE format

sse/http options:
  -u, --url             MCP server URL
  -H, --header          HTTP headers in 'Key: Value' format
```

## Output

The evaluation script generates a detailed report including:

- **Summary Statistics**:
  - Accuracy (correct/total)
  - Average task duration
  - Average tool calls per task
  - Total tool calls

- **Per-Task Results**:
  - Prompt and expected response
  - Actual response from the agent
  - Whether the answer was correct (✅/❌)
  - Duration and tool call details
  - Agent's summary of its approach
  - Agent's feedback on the tools

### Save Report to File

```bash
python scripts/evaluation.py \
  -t stdio \
  -c python \
  -a my_server.py \
  -o evaluation_report.md \
  evaluation.xml
```

## Complete Example Workflow

Here's a complete example of creating and running an evaluation:

1. **Create your evaluation file** (`my_evaluation.xml`):

```xml
<evaluation>
   <qa_pair>
      <question>Find the user who created the most issues in January 2024. What is their username?</question>
      <answer>alice_developer</answer>
   </qa_pair>
   <qa_pair>
      <question>Among all pull requests merged in Q1 2024, which repository had the highest number? Provide the repository name.</question>
      <answer>backend-api</answer>
   </qa_pair>
   <qa_pair>
      <question>Find the project that was completed in December 2023 and had the longest duration from start to finish. How many days did it take?</question>
      <answer>127</answer>
   </qa_pair>
</evaluation>
```

2. **Install dependencies**:

```bash
pip install -r scripts/requirements.txt
export ANTHROPIC_API_KEY=your_api_key
```

3. **Run evaluation**:

```bash
python scripts/evaluation.py \
  -t stdio \
  -c python \
  -a github_mcp_server.py \
  -e GITHUB_TOKEN=ghp_xxx \
  -o github_eval_report.md \
  my_evaluation.xml
```

4. **Review the report** in `github_eval_report.md` to:
   - See which questions passed/failed
   - Read the agent's feedback on your tools
   - Identify areas for improvement
   - Iterate on your MCP server design

## Troubleshooting

### Connection Errors

If you get connection errors:
- **STDIO**: Verify the command and arguments are correct
- **SSE/HTTP**: Check the URL is accessible and headers are correct
- Ensure any required API keys are set in environment variables or headers

### Low Accuracy

If many evaluations fail:
- Review the agent's feedback for each task
- Check if tool descriptions are clear and comprehensive
- Verify input parameters are well-documented
- Consider whether tools return too much or too little data
- Ensure error messages are actionable

### Timeout Issues

If tasks are timing out:
- Use a more capable model (e.g., `claude-3-7-sonnet-20250219`)
- Check if tools are returning too much data
- Verify pagination is working correctly
- Consider simplifying complex questions
FILE:reference/mcp_best_practices.md
# MCP Server Best Practices

## Quick Reference

### Server Naming
- **Python**: `{service}_mcp` (e.g., `slack_mcp`)
- **Node/TypeScript**: `{service}-mcp-server` (e.g., `slack-mcp-server`)

### Tool Naming
- Use snake_case with service prefix
- Format: `{service}_{action}_{resource}`
- Example: `slack_send_message`, `github_create_issue`

### Response Formats
- Support both JSON and Markdown formats
- JSON for programmatic processing
- Markdown for human readability

### Pagination
- Always respect `limit` parameter
- Return `has_more`, `next_offset`, `total_count`
- Default to 20-50 items

### Transport
- **Streamable HTTP**: For remote servers, multi-client scenarios
- **stdio**: For local integrations, command-line tools
- Avoid SSE (deprecated in favor of streamable HTTP)

---

## Server Naming Conventions

Follow these standardized naming patterns:

**Python**: Use format `{service}_mcp` (lowercase with underscores)
- Examples: `slack_mcp`, `github_mcp`, `jira_mcp`

**Node/TypeScript**: Use format `{service}-mcp-server` (lowercase with hyphens)
- Examples: `slack-mcp-server`, `github-mcp-server`, `jira-mcp-server`

The name should be general, descriptive of the service being integrated, easy to infer from the task description, and without version numbers.

---

## Tool Naming and Design

### Tool Naming

1. **Use snake_case**: `search_users`, `create_project`, `get_channel_info`
2. **Include service prefix**: Anticipate that your MCP server may be used alongside other MCP servers
   - Use `slack_send_message` instead of just `send_message`
   - Use `github_create_issue` instead of just `create_issue`
3. **Be action-oriented**: Start with verbs (get, list, search, create, etc.)
4. **Be specific**: Avoid generic names that could conflict with other servers

### Tool Design

- Tool descriptions must narrowly and unambiguously describe functionality
- Descriptions must precisely match actual functionality
- Provide tool annotations (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- Keep tool operations focused and atomic

---

## Response Formats

All tools that return data should support multiple formats:

### JSON Format (`response_format="json"`)
- Machine-readable structured data
- Include all available fields and metadata
- Consistent field names and types
- Use for programmatic processing

### Markdown Format (`response_format="markdown"`, typically default)
- Human-readable formatted text
- Use headers, lists, and formatting for clarity
- Convert timestamps to human-readable format
- Show display names with IDs in parentheses
- Omit verbose metadata

---

## Pagination

For tools that list resources:

- **Always respect the `limit` parameter**
- **Implement pagination**: Use `offset` or cursor-based pagination
- **Return pagination metadata**: Include `has_more`, `next_offset`/`next_cursor`, `total_count`
- **Never load all results into memory**: Especially important for large datasets
- **Default to reasonable limits**: 20-50 items is typical

Example pagination response:
```json
{
  "total": 150,
  "count": 20,
  "offset": 0,
  "items": [...],
  "has_more": true,
  "next_offset": 20
}
```

---

## Transport Options

### Streamable HTTP

**Best for**: Remote servers, web services, multi-client scenarios

**Characteristics**:
- Bidirectional communication over HTTP
- Supports multiple simultaneous clients
- Can be deployed as a web service
- Enables server-to-client notifications

**Use when**:
- Serving multiple clients simultaneously
- Deploying as a cloud service
- Integration with web applications

### stdio

**Best for**: Local integrations, command-line tools

**Characteristics**:
- Standard input/output stream communication
- Simple setup, no network configuration needed
- Runs as a subprocess of the client

**Use when**:
- Building tools for local development environments
- Integrating with desktop applications
- Single-user, single-session scenarios

**Note**: stdio servers should NOT log to stdout (use stderr for logging)

### Transport Selection

| Criterion | stdio | Streamable HTTP |
|-----------|-------|-----------------|
| **Deployment** | Local | Remote |
| **Clients** | Single | Multiple |
| **Complexity** | Low | Medium |
| **Real-time** | No | Yes |

---

## Security Best Practices

### Authentication and Authorization

**OAuth 2.1**:
- Use secure OAuth 2.1 with certificates from recognized authorities
- Validate access tokens before processing requests
- Only accept tokens specifically intended for your server

**API Keys**:
- Store API keys in environment variables, never in code
- Validate keys on server startup
- Provide clear error messages when authentication fails

### Input Validation

- Sanitize file paths to prevent directory traversal
- Validate URLs and external identifiers
- Check parameter sizes and ranges
- Prevent command injection in system calls
- Use schema validation (Pydantic/Zod) for all inputs

### Error Handling

- Don't expose internal errors to clients
- Log security-relevant errors server-side
- Provide helpful but not revealing error messages
- Clean up resources after errors

### DNS Rebinding Protection

For streamable HTTP servers running locally:
- Enable DNS rebinding protection
- Validate the `Origin` header on all incoming connections
- Bind to `127.0.0.1` rather than `0.0.0.0`

---

## Tool Annotations

Provide annotations to help clients understand tool behavior:

| Annotation | Type | Default | Description |
|-----------|------|---------|-------------|
| `readOnlyHint` | boolean | false | Tool does not modify its environment |
| `destructiveHint` | boolean | true | Tool may perform destructive updates |
| `idempotentHint` | boolean | false | Repeated calls with same args have no additional effect |
| `openWorldHint` | boolean | true | Tool interacts with external entities |

**Important**: Annotations are hints, not security guarantees. Clients should not make security-critical decisions based solely on annotations.

---

## Error Handling

- Use standard JSON-RPC error codes
- Report tool errors within result objects (not protocol-level errors)
- Provide helpful, specific error messages with suggested next steps
- Don't expose internal implementation details
- Clean up resources properly on errors

Example error handling:
```typescript
try {
  const result = performOperation();
  return { content: [{ type: "text", text: result }] };
} catch (error) {
  return {
    isError: true,
    content: [{
      type: "text",
      text: `Error: error.message. Try using filter='active_only' to reduce results.`
    }]
  };
}
```

---

## Testing Requirements

Comprehensive testing should cover:

- **Functional testing**: Verify correct execution with valid/invalid inputs
- **Integration testing**: Test interaction with external systems
- **Security testing**: Validate auth, input sanitization, rate limiting
- **Performance testing**: Check behavior under load, timeouts
- **Error handling**: Ensure proper error reporting and cleanup

---

## Documentation Requirements

- Provide clear documentation of all tools and capabilities
- Include working examples (at least 3 per major feature)
- Document security considerations
- Specify required permissions and access levels
- Document rate limits and performance characteristics

FILE:reference/node_mcp_server.md
# Node/TypeScript MCP Server Implementation Guide

## Overview

This document provides Node/TypeScript-specific best practices and examples for implementing MCP servers using the MCP TypeScript SDK. It covers project structure, server setup, tool registration patterns, input validation with Zod, error handling, and complete working examples.

---

## Quick Reference

### Key Imports
```typescript
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import express from "express";
import { z } from "zod";
```

### Server Initialization
```typescript
const server = new McpServer({
  name: "service-mcp-server",
  version: "1.0.0"
});
```

### Tool Registration Pattern
```typescript
server.registerTool(
  "tool_name",
  {
    title: "Tool Display Name",
    description: "What the tool does",
    inputSchema: { param: z.string() },
    outputSchema: { result: z.string() }
  },
  async ({ param }) => {
    const output = { result: `Processed: param` };
    return {
      content: [{ type: "text", text: JSON.stringify(output) }],
      structuredContent: output // Modern pattern for structured data
    };
  }
);
```

---

## MCP TypeScript SDK

The official MCP TypeScript SDK provides:
- `McpServer` class for server initialization
- `registerTool` method for tool registration
- Zod schema integration for runtime input validation
- Type-safe tool handler implementations

**IMPORTANT - Use Modern APIs Only:**
- **DO use**: `server.registerTool()`, `server.registerResource()`, `server.registerPrompt()`
- **DO NOT use**: Old deprecated APIs such as `server.tool()`, `server.setRequestHandler(ListToolsRequestSchema, ...)`, or manual handler registration
- The `register*` methods provide better type safety, automatic schema handling, and are the recommended approach

See the MCP SDK documentation in the references for complete details.

## Server Naming Convention

Node/TypeScript MCP servers must follow this naming pattern:
- **Format**: `{service}-mcp-server` (lowercase with hyphens)
- **Examples**: `github-mcp-server`, `jira-mcp-server`, `stripe-mcp-server`

The name should be:
- General (not tied to specific features)
- Descriptive of the service/API being integrated
- Easy to infer from the task description
- Without version numbers or dates

## Project Structure

Create the following structure for Node/TypeScript MCP servers:

```
{service}-mcp-server/
├── package.json
├── tsconfig.json
├── README.md
├── src/
│   ├── index.ts          # Main entry point with McpServer initialization
│   ├── types.ts          # TypeScript type definitions and interfaces
│   ├── tools/            # Tool implementations (one file per domain)
│   ├── services/         # API clients and shared utilities
│   ├── schemas/          # Zod validation schemas
│   └── constants.ts      # Shared constants (API_URL, CHARACTER_LIMIT, etc.)
└── dist/                 # Built JavaScript files (entry point: dist/index.js)
```

## Tool Implementation

### Tool Naming

Use snake_case for tool names (e.g., "search_users", "create_project", "get_channel_info") with clear, action-oriented names.

**Avoid Naming Conflicts**: Include the service context to prevent overlaps:
- Use "slack_send_message" instead of just "send_message"
- Use "github_create_issue" instead of just "create_issue"
- Use "asana_list_tasks" instead of just "list_tasks"

### Tool Structure

Tools are registered using the `registerTool` method with the following requirements:
- Use Zod schemas for runtime input validation and type safety
- The `description` field must be explicitly provided - JSDoc comments are NOT automatically extracted
- Explicitly provide `title`, `description`, `inputSchema`, and `annotations`
- The `inputSchema` must be a Zod schema object (not a JSON schema)
- Type all parameters and return values explicitly

```typescript
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";

const server = new McpServer({
  name: "example-mcp",
  version: "1.0.0"
});

// Zod schema for input validation
const UserSearchInputSchema = z.object({
  query: z.string()
    .min(2, "Query must be at least 2 characters")
    .max(200, "Query must not exceed 200 characters")
    .describe("Search string to match against names/emails"),
  limit: z.number()
    .int()
    .min(1)
    .max(100)
    .default(20)
    .describe("Maximum results to return"),
  offset: z.number()
    .int()
    .min(0)
    .default(0)
    .describe("Number of results to skip for pagination"),
  response_format: z.nativeEnum(ResponseFormat)
    .default(ResponseFormat.MARKDOWN)
    .describe("Output format: 'markdown' for human-readable or 'json' for machine-readable")
}).strict();

// Type definition from Zod schema
type UserSearchInput = z.infer<typeof UserSearchInputSchema>;

server.registerTool(
  "example_search_users",
  {
    title: "Search Example Users",
    description: `Search for users in the Example system by name, email, or team.

This tool searches across all user profiles in the Example platform, supporting partial matches and various search filters. It does NOT create or modify users, only searches existing ones.

Args:
  - query (string): Search string to match against names/emails
  - limit (number): Maximum results to return, between 1-100 (default: 20)
  - offset (number): Number of results to skip for pagination (default: 0)
  - response_format ('markdown' | 'json'): Output format (default: 'markdown')

Returns:
  For JSON format: Structured data with schema:
  {
    "total": number,           // Total number of matches found
    "count": number,           // Number of results in this response
    "offset": number,          // Current pagination offset
    "users": [
      {
        "id": string,          // User ID (e.g., "U123456789")
        "name": string,        // Full name (e.g., "John Doe")
        "email": string,       // Email address
        "team": string,        // Team name (optional)
        "active": boolean      // Whether user is active
      }
    ],
    "has_more": boolean,       // Whether more results are available
    "next_offset": number      // Offset for next page (if has_more is true)
  }

Examples:
  - Use when: "Find all marketing team members" -> params with query="team:marketing"
  - Use when: "Search for John's account" -> params with query="john"
  - Don't use when: You need to create a user (use example_create_user instead)

Error Handling:
  - Returns "Error: Rate limit exceeded" if too many requests (429 status)
  - Returns "No users found matching '<query>'" if search returns empty`,
    inputSchema: UserSearchInputSchema,
    annotations: {
      readOnlyHint: true,
      destructiveHint: false,
      idempotentHint: true,
      openWorldHint: true
    }
  },
  async (params: UserSearchInput) => {
    try {
      // Input validation is handled by Zod schema
      // Make API request using validated parameters
      const data = await makeApiRequest<any>(
        "users/search",
        "GET",
        undefined,
        {
          q: params.query,
          limit: params.limit,
          offset: params.offset
        }
      );

      const users = data.users || [];
      const total = data.total || 0;

      if (!users.length) {
        return {
          content: [{
            type: "text",
            text: `No users found matching 'params.query'`
          }]
        };
      }

      // Prepare structured output
      const output = {
        total,
        count: users.length,
        offset: params.offset,
        users: users.map((user: any) => ({
          id: user.id,
          name: user.name,
          email: user.email,
          ...(user.team ? { team: user.team } : {}),
          active: user.active ?? true
        })),
        has_more: total > params.offset + users.length,
        ...(total > params.offset + users.length ? {
          next_offset: params.offset + users.length
        } : {})
      };

      // Format text representation based on requested format
      let textContent: string;
      if (params.response_format === ResponseFormat.MARKDOWN) {
        const lines = [`# User Search Results: 'params.query'`, "",
          `Found total users (showing users.length)`, ""];
        for (const user of users) {
          lines.push(`## user.name (user.id)`);
          lines.push(`- **Email**: user.email`);
          if (user.team) lines.push(`- **Team**: user.team`);
          lines.push("");
        }
        textContent = lines.join("\n");
      } else {
        textContent = JSON.stringify(output, null, 2);
      }

      return {
        content: [{ type: "text", text: textContent }],
        structuredContent: output // Modern pattern for structured data
      };
    } catch (error) {
      return {
        content: [{
          type: "text",
          text: handleApiError(error)
        }]
      };
    }
  }
);
```

## Zod Schemas for Input Validation

Zod provides runtime type validation:

```typescript
import { z } from "zod";

// Basic schema with validation
const CreateUserSchema = z.object({
  name: z.string()
    .min(1, "Name is required")
    .max(100, "Name must not exceed 100 characters"),
  email: z.string()
    .email("Invalid email format"),
  age: z.number()
    .int("Age must be a whole number")
    .min(0, "Age cannot be negative")
    .max(150, "Age cannot be greater than 150")
}).strict();  // Use .strict() to forbid extra fields

// Enums
enum ResponseFormat {
  MARKDOWN = "markdown",
  JSON = "json"
}

const SearchSchema = z.object({
  response_format: z.nativeEnum(ResponseFormat)
    .default(ResponseFormat.MARKDOWN)
    .describe("Output format")
});

// Optional fields with defaults
const PaginationSchema = z.object({
  limit: z.number()
    .int()
    .min(1)
    .max(100)
    .default(20)
    .describe("Maximum results to return"),
  offset: z.number()
    .int()
    .min(0)
    .default(0)
    .describe("Number of results to skip")
});
```

## Response Format Options

Support multiple output formats for flexibility:

```typescript
enum ResponseFormat {
  MARKDOWN = "markdown",
  JSON = "json"
}

const inputSchema = z.object({
  query: z.string(),
  response_format: z.nativeEnum(ResponseFormat)
    .default(ResponseFormat.MARKDOWN)
    .describe("Output format: 'markdown' for human-readable or 'json' for machine-readable")
});
```

**Markdown format**:
- Use headers, lists, and formatting for clarity
- Convert timestamps to human-readable format
- Show display names with IDs in parentheses
- Omit verbose metadata
- Group related information logically

**JSON format**:
- Return complete, structured data suitable for programmatic processing
- Include all available fields and metadata
- Use consistent field names and types

## Pagination Implementation

For tools that list resources:

```typescript
const ListSchema = z.object({
  limit: z.number().int().min(1).max(100).default(20),
  offset: z.number().int().min(0).default(0)
});

async function listItems(params: z.infer<typeof ListSchema>) {
  const data = await apiRequest(params.limit, params.offset);

  const response = {
    total: data.total,
    count: data.items.length,
    offset: params.offset,
    items: data.items,
    has_more: data.total > params.offset + data.items.length,
    next_offset: data.total > params.offset + data.items.length
      ? params.offset + data.items.length
      : undefined
  };

  return JSON.stringify(response, null, 2);
}
```

## Character Limits and Truncation

Add a CHARACTER_LIMIT constant to prevent overwhelming responses:

```typescript
// At module level in constants.ts
export const CHARACTER_LIMIT = 25000;  // Maximum response size in characters

async function searchTool(params: SearchInput) {
  let result = generateResponse(data);

  // Check character limit and truncate if needed
  if (result.length > CHARACTER_LIMIT) {
    const truncatedData = data.slice(0, Math.max(1, data.length / 2));
    response.data = truncatedData;
    response.truncated = true;
    response.truncation_message =
      `Response truncated from data.length to truncatedData.length items. ` +
      `Use 'offset' parameter or add filters to see more results.`;
    result = JSON.stringify(response, null, 2);
  }

  return result;
}
```

## Error Handling

Provide clear, actionable error messages:

```typescript
import axios, { AxiosError } from "axios";

function handleApiError(error: unknown): string {
  if (error instanceof AxiosError) {
    if (error.response) {
      switch (error.response.status) {
        case 404:
          return "Error: Resource not found. Please check the ID is correct.";
        case 403:
          return "Error: Permission denied. You don't have access to this resource.";
        case 429:
          return "Error: Rate limit exceeded. Please wait before making more requests.";
        default:
          return `Error: API request failed with status error.response.status`;
      }
    } else if (error.code === "ECONNABORTED") {
      return "Error: Request timed out. Please try again.";
    }
  }
  return `Error: Unexpected error occurred: String(error)`;
}
```

## Shared Utilities

Extract common functionality into reusable functions:

```typescript
// Shared API request function
async function makeApiRequest<T>(
  endpoint: string,
  method: "GET" | "POST" | "PUT" | "DELETE" = "GET",
  data?: any,
  params?: any
): Promise<T> {
  try {
    const response = await axios({
      method,
      url: `API_BASE_URL/endpoint`,
      data,
      params,
      timeout: 30000,
      headers: {
        "Content-Type": "application/json",
        "Accept": "application/json"
      }
    });
    return response.data;
  } catch (error) {
    throw error;
  }
}
```

## Async/Await Best Practices

Always use async/await for network requests and I/O operations:

```typescript
// Good: Async network request
async function fetchData(resourceId: string): Promise<ResourceData> {
  const response = await axios.get(`API_URL/resource/resourceId`);
  return response.data;
}

// Bad: Promise chains
function fetchData(resourceId: string): Promise<ResourceData> {
  return axios.get(`API_URL/resource/resourceId`)
    .then(response => response.data);  // Harder to read and maintain
}
```

## TypeScript Best Practices

1. **Use Strict TypeScript**: Enable strict mode in tsconfig.json
2. **Define Interfaces**: Create clear interface definitions for all data structures
3. **Avoid `any`**: Use proper types or `unknown` instead of `any`
4. **Zod for Runtime Validation**: Use Zod schemas to validate external data
5. **Type Guards**: Create type guard functions for complex type checking
6. **Error Handling**: Always use try-catch with proper error type checking
7. **Null Safety**: Use optional chaining (`?.`) and nullish coalescing (`??`)

```typescript
// Good: Type-safe with Zod and interfaces
interface UserResponse {
  id: string;
  name: string;
  email: string;
  team?: string;
  active: boolean;
}

const UserSchema = z.object({
  id: z.string(),
  name: z.string(),
  email: z.string().email(),
  team: z.string().optional(),
  active: z.boolean()
});

type User = z.infer<typeof UserSchema>;

async function getUser(id: string): Promise<User> {
  const data = await apiCall(`/users/id`);
  return UserSchema.parse(data);  // Runtime validation
}

// Bad: Using any
async function getUser(id: string): Promise<any> {
  return await apiCall(`/users/id`);  // No type safety
}
```

## Package Configuration

### package.json

```json
{
  "name": "{service}-mcp-server",
  "version": "1.0.0",
  "description": "MCP server for {Service} API integration",
  "type": "module",
  "main": "dist/index.js",
  "scripts": {
    "start": "node dist/index.js",
    "dev": "tsx watch src/index.ts",
    "build": "tsc",
    "clean": "rm -rf dist"
  },
  "engines": {
    "node": ">=18"
  },
  "dependencies": {
    "@modelcontextprotocol/sdk": "^1.6.1",
    "axios": "^1.7.9",
    "zod": "^3.23.8"
  },
  "devDependencies": {
    "@types/node": "^22.10.0",
    "tsx": "^4.19.2",
    "typescript": "^5.7.2"
  }
}
```

### tsconfig.json

```json
{
  "compilerOptions": {
    "target": "ES2022",
    "module": "Node16",
    "moduleResolution": "Node16",
    "lib": ["ES2022"],
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "declaration": true,
    "declarationMap": true,
    "sourceMap": true,
    "allowSyntheticDefaultImports": true
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}
```

## Complete Example

```typescript
#!/usr/bin/env node
/**
 * MCP Server for Example Service.
 *
 * This server provides tools to interact with Example API, including user search,
 * project management, and data export capabilities.
 */

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";
import axios, { AxiosError } from "axios";

// Constants
const API_BASE_URL = "https://api.example.com/v1";
const CHARACTER_LIMIT = 25000;

// Enums
enum ResponseFormat {
  MARKDOWN = "markdown",
  JSON = "json"
}

// Zod schemas
const UserSearchInputSchema = z.object({
  query: z.string()
    .min(2, "Query must be at least 2 characters")
    .max(200, "Query must not exceed 200 characters")
    .describe("Search string to match against names/emails"),
  limit: z.number()
    .int()
    .min(1)
    .max(100)
    .default(20)
    .describe("Maximum results to return"),
  offset: z.number()
    .int()
    .min(0)
    .default(0)
    .describe("Number of results to skip for pagination"),
  response_format: z.nativeEnum(ResponseFormat)
    .default(ResponseFormat.MARKDOWN)
    .describe("Output format: 'markdown' for human-readable or 'json' for machine-readable")
}).strict();

type UserSearchInput = z.infer<typeof UserSearchInputSchema>;

// Shared utility functions
async function makeApiRequest<T>(
  endpoint: string,
  method: "GET" | "POST" | "PUT" | "DELETE" = "GET",
  data?: any,
  params?: any
): Promise<T> {
  try {
    const response = await axios({
      method,
      url: `API_BASE_URL/endpoint`,
      data,
      params,
      timeout: 30000,
      headers: {
        "Content-Type": "application/json",
        "Accept": "application/json"
      }
    });
    return response.data;
  } catch (error) {
    throw error;
  }
}

function handleApiError(error: unknown): string {
  if (error instanceof AxiosError) {
    if (error.response) {
      switch (error.response.status) {
        case 404:
          return "Error: Resource not found. Please check the ID is correct.";
        case 403:
          return "Error: Permission denied. You don't have access to this resource.";
        case 429:
          return "Error: Rate limit exceeded. Please wait before making more requests.";
        default:
          return `Error: API request failed with status error.response.status`;
      }
    } else if (error.code === "ECONNABORTED") {
      return "Error: Request timed out. Please try again.";
    }
  }
  return `Error: Unexpected error occurred: String(error)`;
}

// Create MCP server instance
const server = new McpServer({
  name: "example-mcp",
  version: "1.0.0"
});

// Register tools
server.registerTool(
  "example_search_users",
  {
    title: "Search Example Users",
    description: `[Full description as shown above]`,
    inputSchema: UserSearchInputSchema,
    annotations: {
      readOnlyHint: true,
      destructiveHint: false,
      idempotentHint: true,
      openWorldHint: true
    }
  },
  async (params: UserSearchInput) => {
    // Implementation as shown above
  }
);

// Main function
// For stdio (local):
async function runStdio() {
  if (!process.env.EXAMPLE_API_KEY) {
    console.error("ERROR: EXAMPLE_API_KEY environment variable is required");
    process.exit(1);
  }

  const transport = new StdioServerTransport();
  await server.connect(transport);
  console.error("MCP server running via stdio");
}

// For streamable HTTP (remote):
async function runHTTP() {
  if (!process.env.EXAMPLE_API_KEY) {
    console.error("ERROR: EXAMPLE_API_KEY environment variable is required");
    process.exit(1);
  }

  const app = express();
  app.use(express.json());

  app.post('/mcp', async (req, res) => {
    const transport = new StreamableHTTPServerTransport({
      sessionIdGenerator: undefined,
      enableJsonResponse: true
    });
    res.on('close', () => transport.close());
    await server.connect(transport);
    await transport.handleRequest(req, res, req.body);
  });

  const port = parseInt(process.env.PORT || '3000');
  app.listen(port, () => {
    console.error(`MCP server running on http://localhost:port/mcp`);
  });
}

// Choose transport based on environment
const transport = process.env.TRANSPORT || 'stdio';
if (transport === 'http') {
  runHTTP().catch(error => {
    console.error("Server error:", error);
    process.exit(1);
  });
} else {
  runStdio().catch(error => {
    console.error("Server error:", error);
    process.exit(1);
  });
}
```

---

## Advanced MCP Features

### Resource Registration

Expose data as resources for efficient, URI-based access:

```typescript
import { ResourceTemplate } from "@modelcontextprotocol/sdk/types.js";

// Register a resource with URI template
server.registerResource(
  {
    uri: "file://documents/{name}",
    name: "Document Resource",
    description: "Access documents by name",
    mimeType: "text/plain"
  },
  async (uri: string) => {
    // Extract parameter from URI
    const match = uri.match(/^file:\/\/documents\/(.+)$/);
    if (!match) {
      throw new Error("Invalid URI format");
    }

    const documentName = match[1];
    const content = await loadDocument(documentName);

    return {
      contents: [{
        uri,
        mimeType: "text/plain",
        text: content
      }]
    };
  }
);

// List available resources dynamically
server.registerResourceList(async () => {
  const documents = await getAvailableDocuments();
  return {
    resources: documents.map(doc => ({
      uri: `file://documents/doc.name`,
      name: doc.name,
      mimeType: "text/plain",
      description: doc.description
    }))
  };
});
```

**When to use Resources vs Tools:**
- **Resources**: For data access with simple URI-based parameters
- **Tools**: For complex operations requiring validation and business logic
- **Resources**: When data is relatively static or template-based
- **Tools**: When operations have side effects or complex workflows

### Transport Options

The TypeScript SDK supports two main transport mechanisms:

#### Streamable HTTP (Recommended for Remote Servers)

```typescript
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import express from "express";

const app = express();
app.use(express.json());

app.post('/mcp', async (req, res) => {
  // Create new transport for each request (stateless, prevents request ID collisions)
  const transport = new StreamableHTTPServerTransport({
    sessionIdGenerator: undefined,
    enableJsonResponse: true
  });

  res.on('close', () => transport.close());

  await server.connect(transport);
  await transport.handleRequest(req, res, req.body);
});

app.listen(3000);
```

#### stdio (For Local Integrations)

```typescript
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

const transport = new StdioServerTransport();
await server.connect(transport);
```

**Transport selection:**
- **Streamable HTTP**: Web services, remote access, multiple clients
- **stdio**: Command-line tools, local development, subprocess integration

### Notification Support

Notify clients when server state changes:

```typescript
// Notify when tools list changes
server.notification({
  method: "notifications/tools/list_changed"
});

// Notify when resources change
server.notification({
  method: "notifications/resources/list_changed"
});
```

Use notifications sparingly - only when server capabilities genuinely change.

---

## Code Best Practices

### Code Composability and Reusability

Your implementation MUST prioritize composability and code reuse:

1. **Extract Common Functionality**:
   - Create reusable helper functions for operations used across multiple tools
   - Build shared API clients for HTTP requests instead of duplicating code
   - Centralize error handling logic in utility functions
   - Extract business logic into dedicated functions that can be composed
   - Extract shared markdown or JSON field selection & formatting functionality

2. **Avoid Duplication**:
   - NEVER copy-paste similar code between tools
   - If you find yourself writing similar logic twice, extract it into a function
   - Common operations like pagination, filtering, field selection, and formatting should be shared
   - Authentication/authorization logic should be centralized

## Building and Running

Always build your TypeScript code before running:

```bash
# Build the project
npm run build

# Run the server
npm start

# Development with auto-reload
npm run dev
```

Always ensure `npm run build` completes successfully before considering the implementation complete.

## Quality Checklist

Before finalizing your Node/TypeScript MCP server implementation, ensure:

### Strategic Design
- [ ] Tools enable complete workflows, not just API endpoint wrappers
- [ ] Tool names reflect natural task subdivisions
- [ ] Response formats optimize for agent context efficiency
- [ ] Human-readable identifiers used where appropriate
- [ ] Error messages guide agents toward correct usage

### Implementation Quality
- [ ] FOCUSED IMPLEMENTATION: Most important and valuable tools implemented
- [ ] All tools registered using `registerTool` with complete configuration
- [ ] All tools include `title`, `description`, `inputSchema`, and `annotations`
- [ ] Annotations correctly set (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- [ ] All tools use Zod schemas for runtime input validation with `.strict()` enforcement
- [ ] All Zod schemas have proper constraints and descriptive error messages
- [ ] All tools have comprehensive descriptions with explicit input/output types
- [ ] Descriptions include return value examples and complete schema documentation
- [ ] Error messages are clear, actionable, and educational

### TypeScript Quality
- [ ] TypeScript interfaces are defined for all data structures
- [ ] Strict TypeScript is enabled in tsconfig.json
- [ ] No use of `any` type - use `unknown` or proper types instead
- [ ] All async functions have explicit Promise<T> return types
- [ ] Error handling uses proper type guards (e.g., `axios.isAxiosError`, `z.ZodError`)

### Advanced Features (where applicable)
- [ ] Resources registered for appropriate data endpoints
- [ ] Appropriate transport configured (stdio or streamable HTTP)
- [ ] Notifications implemented for dynamic server capabilities
- [ ] Type-safe with SDK interfaces

### Project Configuration
- [ ] Package.json includes all necessary dependencies
- [ ] Build script produces working JavaScript in dist/ directory
- [ ] Main entry point is properly configured as dist/index.js
- [ ] Server name follows format: `{service}-mcp-server`
- [ ] tsconfig.json properly configured with strict mode

### Code Quality
- [ ] Pagination is properly implemented where applicable
- [ ] Large responses check CHARACTER_LIMIT constant and truncate with clear messages
- [ ] Filtering options are provided for potentially large result sets
- [ ] All network operations handle timeouts and connection errors gracefully
- [ ] Common functionality is extracted into reusable functions
- [ ] Return types are consistent across similar operations

### Testing and Build
- [ ] `npm run build` completes successfully without errors
- [ ] dist/index.js created and executable
- [ ] Server runs: `node dist/index.js --help`
- [ ] All imports resolve correctly
- [ ] Sample tool calls work as expected
FILE:reference/python_mcp_server.md
# Python MCP Server Implementation Guide

## Overview

This document provides Python-specific best practices and examples for implementing MCP servers using the MCP Python SDK. It covers server setup, tool registration patterns, input validation with Pydantic, error handling, and complete working examples.

---

## Quick Reference

### Key Imports
```python
from mcp.server.fastmcp import FastMCP
from pydantic import BaseModel, Field, field_validator, ConfigDict
from typing import Optional, List, Dict, Any
from enum import Enum
import httpx
```

### Server Initialization
```python
mcp = FastMCP("service_mcp")
```

### Tool Registration Pattern
```python
@mcp.tool(name="tool_name", annotations={...})
async def tool_function(params: InputModel) -> str:
    # Implementation
    pass
```

---

## MCP Python SDK and FastMCP

The official MCP Python SDK provides FastMCP, a high-level framework for building MCP servers. It provides:
- Automatic description and inputSchema generation from function signatures and docstrings
- Pydantic model integration for input validation
- Decorator-based tool registration with `@mcp.tool`

**For complete SDK documentation, use WebFetch to load:**
`https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md`

## Server Naming Convention

Python MCP servers must follow this naming pattern:
- **Format**: `{service}_mcp` (lowercase with underscores)
- **Examples**: `github_mcp`, `jira_mcp`, `stripe_mcp`

The name should be:
- General (not tied to specific features)
- Descriptive of the service/API being integrated
- Easy to infer from the task description
- Without version numbers or dates

## Tool Implementation

### Tool Naming

Use snake_case for tool names (e.g., "search_users", "create_project", "get_channel_info") with clear, action-oriented names.

**Avoid Naming Conflicts**: Include the service context to prevent overlaps:
- Use "slack_send_message" instead of just "send_message"
- Use "github_create_issue" instead of just "create_issue"
- Use "asana_list_tasks" instead of just "list_tasks"

### Tool Structure with FastMCP

Tools are defined using the `@mcp.tool` decorator with Pydantic models for input validation:

```python
from pydantic import BaseModel, Field, ConfigDict
from mcp.server.fastmcp import FastMCP

# Initialize the MCP server
mcp = FastMCP("example_mcp")

# Define Pydantic model for input validation
class ServiceToolInput(BaseModel):
    '''Input model for service tool operation.'''
    model_config = ConfigDict(
        str_strip_whitespace=True,  # Auto-strip whitespace from strings
        validate_assignment=True,    # Validate on assignment
        extra='forbid'              # Forbid extra fields
    )

    param1: str = Field(..., description="First parameter description (e.g., 'user123', 'project-abc')", min_length=1, max_length=100)
    param2: Optional[int] = Field(default=None, description="Optional integer parameter with constraints", ge=0, le=1000)
    tags: Optional[List[str]] = Field(default_factory=list, description="List of tags to apply", max_items=10)

@mcp.tool(
    name="service_tool_name",
    annotations={
        "title": "Human-Readable Tool Title",
        "readOnlyHint": True,     # Tool does not modify environment
        "destructiveHint": False,  # Tool does not perform destructive operations
        "idempotentHint": True,    # Repeated calls have no additional effect
        "openWorldHint": False     # Tool does not interact with external entities
    }
)
async def service_tool_name(params: ServiceToolInput) -> str:
    '''Tool description automatically becomes the 'description' field.

    This tool performs a specific operation on the service. It validates all inputs
    using the ServiceToolInput Pydantic model before processing.

    Args:
        params (ServiceToolInput): Validated input parameters containing:
            - param1 (str): First parameter description
            - param2 (Optional[int]): Optional parameter with default
            - tags (Optional[List[str]]): List of tags

    Returns:
        str: JSON-formatted response containing operation results
    '''
    # Implementation here
    pass
```

## Pydantic v2 Key Features

- Use `model_config` instead of nested `Config` class
- Use `field_validator` instead of deprecated `validator`
- Use `model_dump()` instead of deprecated `dict()`
- Validators require `@classmethod` decorator
- Type hints are required for validator methods

```python
from pydantic import BaseModel, Field, field_validator, ConfigDict

class CreateUserInput(BaseModel):
    model_config = ConfigDict(
        str_strip_whitespace=True,
        validate_assignment=True
    )

    name: str = Field(..., description="User's full name", min_length=1, max_length=100)
    email: str = Field(..., description="User's email address", pattern=r'^[\w\.-]+@[\w\.-]+\.\w+$')
    age: int = Field(..., description="User's age", ge=0, le=150)

    @field_validator('email')
    @classmethod
    def validate_email(cls, v: str) -> str:
        if not v.strip():
            raise ValueError("Email cannot be empty")
        return v.lower()
```

## Response Format Options

Support multiple output formats for flexibility:

```python
from enum import Enum

class ResponseFormat(str, Enum):
    '''Output format for tool responses.'''
    MARKDOWN = "markdown"
    JSON = "json"

class UserSearchInput(BaseModel):
    query: str = Field(..., description="Search query")
    response_format: ResponseFormat = Field(
        default=ResponseFormat.MARKDOWN,
        description="Output format: 'markdown' for human-readable or 'json' for machine-readable"
    )
```

**Markdown format**:
- Use headers, lists, and formatting for clarity
- Convert timestamps to human-readable format (e.g., "2024-01-15 10:30:00 UTC" instead of epoch)
- Show display names with IDs in parentheses (e.g., "@john.doe (U123456)")
- Omit verbose metadata (e.g., show only one profile image URL, not all sizes)
- Group related information logically

**JSON format**:
- Return complete, structured data suitable for programmatic processing
- Include all available fields and metadata
- Use consistent field names and types

## Pagination Implementation

For tools that list resources:

```python
class ListInput(BaseModel):
    limit: Optional[int] = Field(default=20, description="Maximum results to return", ge=1, le=100)
    offset: Optional[int] = Field(default=0, description="Number of results to skip for pagination", ge=0)

async def list_items(params: ListInput) -> str:
    # Make API request with pagination
    data = await api_request(limit=params.limit, offset=params.offset)

    # Return pagination info
    response = {
        "total": data["total"],
        "count": len(data["items"]),
        "offset": params.offset,
        "items": data["items"],
        "has_more": data["total"] > params.offset + len(data["items"]),
        "next_offset": params.offset + len(data["items"]) if data["total"] > params.offset + len(data["items"]) else None
    }
    return json.dumps(response, indent=2)
```

## Error Handling

Provide clear, actionable error messages:

```python
def _handle_api_error(e: Exception) -> str:
    '''Consistent error formatting across all tools.'''
    if isinstance(e, httpx.HTTPStatusError):
        if e.response.status_code == 404:
            return "Error: Resource not found. Please check the ID is correct."
        elif e.response.status_code == 403:
            return "Error: Permission denied. You don't have access to this resource."
        elif e.response.status_code == 429:
            return "Error: Rate limit exceeded. Please wait before making more requests."
        return f"Error: API request failed with status {e.response.status_code}"
    elif isinstance(e, httpx.TimeoutException):
        return "Error: Request timed out. Please try again."
    return f"Error: Unexpected error occurred: {type(e).__name__}"
```

## Shared Utilities

Extract common functionality into reusable functions:

```python
# Shared API request function
async def _make_api_request(endpoint: str, method: str = "GET", **kwargs) -> dict:
    '''Reusable function for all API calls.'''
    async with httpx.AsyncClient() as client:
        response = await client.request(
            method,
            f"{API_BASE_URL}/{endpoint}",
            timeout=30.0,
            **kwargs
        )
        response.raise_for_status()
        return response.json()
```

## Async/Await Best Practices

Always use async/await for network requests and I/O operations:

```python
# Good: Async network request
async def fetch_data(resource_id: str) -> dict:
    async with httpx.AsyncClient() as client:
        response = await client.get(f"{API_URL}/resource/{resource_id}")
        response.raise_for_status()
        return response.json()

# Bad: Synchronous request
def fetch_data(resource_id: str) -> dict:
    response = requests.get(f"{API_URL}/resource/{resource_id}")  # Blocks
    return response.json()
```

## Type Hints

Use type hints throughout:

```python
from typing import Optional, List, Dict, Any

async def get_user(user_id: str) -> Dict[str, Any]:
    data = await fetch_user(user_id)
    return {"id": data["id"], "name": data["name"]}
```

## Tool Docstrings

Every tool must have comprehensive docstrings with explicit type information:

```python
async def search_users(params: UserSearchInput) -> str:
    '''
    Search for users in the Example system by name, email, or team.

    This tool searches across all user profiles in the Example platform,
    supporting partial matches and various search filters. It does NOT
    create or modify users, only searches existing ones.

    Args:
        params (UserSearchInput): Validated input parameters containing:
            - query (str): Search string to match against names/emails (e.g., "john", "@example.com", "team:marketing")
            - limit (Optional[int]): Maximum results to return, between 1-100 (default: 20)
            - offset (Optional[int]): Number of results to skip for pagination (default: 0)

    Returns:
        str: JSON-formatted string containing search results with the following schema:

        Success response:
        {
            "total": int,           # Total number of matches found
            "count": int,           # Number of results in this response
            "offset": int,          # Current pagination offset
            "users": [
                {
                    "id": str,      # User ID (e.g., "U123456789")
                    "name": str,    # Full name (e.g., "John Doe")
                    "email": str,   # Email address (e.g., "john@example.com")
                    "team": str     # Team name (e.g., "Marketing") - optional
                }
            ]
        }

        Error response:
        "Error: <error message>" or "No users found matching '<query>'"

    Examples:
        - Use when: "Find all marketing team members" -> params with query="team:marketing"
        - Use when: "Search for John's account" -> params with query="john"
        - Don't use when: You need to create a user (use example_create_user instead)
        - Don't use when: You have a user ID and need full details (use example_get_user instead)

    Error Handling:
        - Input validation errors are handled by Pydantic model
        - Returns "Error: Rate limit exceeded" if too many requests (429 status)
        - Returns "Error: Invalid API authentication" if API key is invalid (401 status)
        - Returns formatted list of results or "No users found matching 'query'"
    '''
```

## Complete Example

See below for a complete Python MCP server example:

```python
#!/usr/bin/env python3
'''
MCP Server for Example Service.

This server provides tools to interact with Example API, including user search,
project management, and data export capabilities.
'''

from typing import Optional, List, Dict, Any
from enum import Enum
import httpx
from pydantic import BaseModel, Field, field_validator, ConfigDict
from mcp.server.fastmcp import FastMCP

# Initialize the MCP server
mcp = FastMCP("example_mcp")

# Constants
API_BASE_URL = "https://api.example.com/v1"

# Enums
class ResponseFormat(str, Enum):
    '''Output format for tool responses.'''
    MARKDOWN = "markdown"
    JSON = "json"

# Pydantic Models for Input Validation
class UserSearchInput(BaseModel):
    '''Input model for user search operations.'''
    model_config = ConfigDict(
        str_strip_whitespace=True,
        validate_assignment=True
    )

    query: str = Field(..., description="Search string to match against names/emails", min_length=2, max_length=200)
    limit: Optional[int] = Field(default=20, description="Maximum results to return", ge=1, le=100)
    offset: Optional[int] = Field(default=0, description="Number of results to skip for pagination", ge=0)
    response_format: ResponseFormat = Field(default=ResponseFormat.MARKDOWN, description="Output format")

    @field_validator('query')
    @classmethod
    def validate_query(cls, v: str) -> str:
        if not v.strip():
            raise ValueError("Query cannot be empty or whitespace only")
        return v.strip()

# Shared utility functions
async def _make_api_request(endpoint: str, method: str = "GET", **kwargs) -> dict:
    '''Reusable function for all API calls.'''
    async with httpx.AsyncClient() as client:
        response = await client.request(
            method,
            f"{API_BASE_URL}/{endpoint}",
            timeout=30.0,
            **kwargs
        )
        response.raise_for_status()
        return response.json()

def _handle_api_error(e: Exception) -> str:
    '''Consistent error formatting across all tools.'''
    if isinstance(e, httpx.HTTPStatusError):
        if e.response.status_code == 404:
            return "Error: Resource not found. Please check the ID is correct."
        elif e.response.status_code == 403:
            return "Error: Permission denied. You don't have access to this resource."
        elif e.response.status_code == 429:
            return "Error: Rate limit exceeded. Please wait before making more requests."
        return f"Error: API request failed with status {e.response.status_code}"
    elif isinstance(e, httpx.TimeoutException):
        return "Error: Request timed out. Please try again."
    return f"Error: Unexpected error occurred: {type(e).__name__}"

# Tool definitions
@mcp.tool(
    name="example_search_users",
    annotations={
        "title": "Search Example Users",
        "readOnlyHint": True,
        "destructiveHint": False,
        "idempotentHint": True,
        "openWorldHint": True
    }
)
async def example_search_users(params: UserSearchInput) -> str:
    '''Search for users in the Example system by name, email, or team.

    [Full docstring as shown above]
    '''
    try:
        # Make API request using validated parameters
        data = await _make_api_request(
            "users/search",
            params={
                "q": params.query,
                "limit": params.limit,
                "offset": params.offset
            }
        )

        users = data.get("users", [])
        total = data.get("total", 0)

        if not users:
            return f"No users found matching '{params.query}'"

        # Format response based on requested format
        if params.response_format == ResponseFormat.MARKDOWN:
            lines = [f"# User Search Results: '{params.query}'", ""]
            lines.append(f"Found {total} users (showing {len(users)})")
            lines.append("")

            for user in users:
                lines.append(f"## {user['name']} ({user['id']})")
                lines.append(f"- **Email**: {user['email']}")
                if user.get('team'):
                    lines.append(f"- **Team**: {user['team']}")
                lines.append("")

            return "\n".join(lines)

        else:
            # Machine-readable JSON format
            import json
            response = {
                "total": total,
                "count": len(users),
                "offset": params.offset,
                "users": users
            }
            return json.dumps(response, indent=2)

    except Exception as e:
        return _handle_api_error(e)

if __name__ == "__main__":
    mcp.run()
```

---

## Advanced FastMCP Features

### Context Parameter Injection

FastMCP can automatically inject a `Context` parameter into tools for advanced capabilities like logging, progress reporting, resource reading, and user interaction:

```python
from mcp.server.fastmcp import FastMCP, Context

mcp = FastMCP("example_mcp")

@mcp.tool()
async def advanced_search(query: str, ctx: Context) -> str:
    '''Advanced tool with context access for logging and progress.'''

    # Report progress for long operations
    await ctx.report_progress(0.25, "Starting search...")

    # Log information for debugging
    await ctx.log_info("Processing query", {"query": query, "timestamp": datetime.now()})

    # Perform search
    results = await search_api(query)
    await ctx.report_progress(0.75, "Formatting results...")

    # Access server configuration
    server_name = ctx.fastmcp.name

    return format_results(results)

@mcp.tool()
async def interactive_tool(resource_id: str, ctx: Context) -> str:
    '''Tool that can request additional input from users.'''

    # Request sensitive information when needed
    api_key = await ctx.elicit(
        prompt="Please provide your API key:",
        input_type="password"
    )

    # Use the provided key
    return await api_call(resource_id, api_key)
```

**Context capabilities:**
- `ctx.report_progress(progress, message)` - Report progress for long operations
- `ctx.log_info(message, data)` / `ctx.log_error()` / `ctx.log_debug()` - Logging
- `ctx.elicit(prompt, input_type)` - Request input from users
- `ctx.fastmcp.name` - Access server configuration
- `ctx.read_resource(uri)` - Read MCP resources

### Resource Registration

Expose data as resources for efficient, template-based access:

```python
@mcp.resource("file://documents/{name}")
async def get_document(name: str) -> str:
    '''Expose documents as MCP resources.

    Resources are useful for static or semi-static data that doesn't
    require complex parameters. They use URI templates for flexible access.
    '''
    document_path = f"./docs/{name}"
    with open(document_path, "r") as f:
        return f.read()

@mcp.resource("config://settings/{key}")
async def get_setting(key: str, ctx: Context) -> str:
    '''Expose configuration as resources with context.'''
    settings = await load_settings()
    return json.dumps(settings.get(key, {}))
```

**When to use Resources vs Tools:**
- **Resources**: For data access with simple parameters (URI templates)
- **Tools**: For complex operations with validation and business logic

### Structured Output Types

FastMCP supports multiple return types beyond strings:

```python
from typing import TypedDict
from dataclasses import dataclass
from pydantic import BaseModel

# TypedDict for structured returns
class UserData(TypedDict):
    id: str
    name: str
    email: str

@mcp.tool()
async def get_user_typed(user_id: str) -> UserData:
    '''Returns structured data - FastMCP handles serialization.'''
    return {"id": user_id, "name": "John Doe", "email": "john@example.com"}

# Pydantic models for complex validation
class DetailedUser(BaseModel):
    id: str
    name: str
    email: str
    created_at: datetime
    metadata: Dict[str, Any]

@mcp.tool()
async def get_user_detailed(user_id: str) -> DetailedUser:
    '''Returns Pydantic model - automatically generates schema.'''
    user = await fetch_user(user_id)
    return DetailedUser(**user)
```

### Lifespan Management

Initialize resources that persist across requests:

```python
from contextlib import asynccontextmanager

@asynccontextmanager
async def app_lifespan():
    '''Manage resources that live for the server's lifetime.'''
    # Initialize connections, load config, etc.
    db = await connect_to_database()
    config = load_configuration()

    # Make available to all tools
    yield {"db": db, "config": config}

    # Cleanup on shutdown
    await db.close()

mcp = FastMCP("example_mcp", lifespan=app_lifespan)

@mcp.tool()
async def query_data(query: str, ctx: Context) -> str:
    '''Access lifespan resources through context.'''
    db = ctx.request_context.lifespan_state["db"]
    results = await db.query(query)
    return format_results(results)
```

### Transport Options

FastMCP supports two main transport mechanisms:

```python
# stdio transport (for local tools) - default
if __name__ == "__main__":
    mcp.run()

# Streamable HTTP transport (for remote servers)
if __name__ == "__main__":
    mcp.run(transport="streamable_http", port=8000)
```

**Transport selection:**
- **stdio**: Command-line tools, local integrations, subprocess execution
- **Streamable HTTP**: Web services, remote access, multiple clients

---

## Code Best Practices

### Code Composability and Reusability

Your implementation MUST prioritize composability and code reuse:

1. **Extract Common Functionality**:
   - Create reusable helper functions for operations used across multiple tools
   - Build shared API clients for HTTP requests instead of duplicating code
   - Centralize error handling logic in utility functions
   - Extract business logic into dedicated functions that can be composed
   - Extract shared markdown or JSON field selection & formatting functionality

2. **Avoid Duplication**:
   - NEVER copy-paste similar code between tools
   - If you find yourself writing similar logic twice, extract it into a function
   - Common operations like pagination, filtering, field selection, and formatting should be shared
   - Authentication/authorization logic should be centralized

### Python-Specific Best Practices

1. **Use Type Hints**: Always include type annotations for function parameters and return values
2. **Pydantic Models**: Define clear Pydantic models for all input validation
3. **Avoid Manual Validation**: Let Pydantic handle input validation with constraints
4. **Proper Imports**: Group imports (standard library, third-party, local)
5. **Error Handling**: Use specific exception types (httpx.HTTPStatusError, not generic Exception)
6. **Async Context Managers**: Use `async with` for resources that need cleanup
7. **Constants**: Define module-level constants in UPPER_CASE

## Quality Checklist

Before finalizing your Python MCP server implementation, ensure:

### Strategic Design
- [ ] Tools enable complete workflows, not just API endpoint wrappers
- [ ] Tool names reflect natural task subdivisions
- [ ] Response formats optimize for agent context efficiency
- [ ] Human-readable identifiers used where appropriate
- [ ] Error messages guide agents toward correct usage

### Implementation Quality
- [ ] FOCUSED IMPLEMENTATION: Most important and valuable tools implemented
- [ ] All tools have descriptive names and documentation
- [ ] Return types are consistent across similar operations
- [ ] Error handling is implemented for all external calls
- [ ] Server name follows format: `{service}_mcp`
- [ ] All network operations use async/await
- [ ] Common functionality is extracted into reusable functions
- [ ] Error messages are clear, actionable, and educational
- [ ] Outputs are properly validated and formatted

### Tool Configuration
- [ ] All tools implement 'name' and 'annotations' in the decorator
- [ ] Annotations correctly set (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- [ ] All tools use Pydantic BaseModel for input validation with Field() definitions
- [ ] All Pydantic Fields have explicit types and descriptions with constraints
- [ ] All tools have comprehensive docstrings with explicit input/output types
- [ ] Docstrings include complete schema structure for dict/JSON returns
- [ ] Pydantic models handle input validation (no manual validation needed)

### Advanced Features (where applicable)
- [ ] Context injection used for logging, progress, or elicitation
- [ ] Resources registered for appropriate data endpoints
- [ ] Lifespan management implemented for persistent connections
- [ ] Structured output types used (TypedDict, Pydantic models)
- [ ] Appropriate transport configured (stdio or streamable HTTP)

### Code Quality
- [ ] File includes proper imports including Pydantic imports
- [ ] Pagination is properly implemented where applicable
- [ ] Filtering options are provided for potentially large result sets
- [ ] All async functions are properly defined with `async def`
- [ ] HTTP client usage follows async patterns with proper context managers
- [ ] Type hints are used throughout the code
- [ ] Constants are defined at module level in UPPER_CASE

### Testing
- [ ] Server runs successfully: `python your_server.py --help`
- [ ] All imports resolve correctly
- [ ] Sample tool calls work as expected
- [ ] Error scenarios handled gracefully
FILE:scripts/connections.py
"""Lightweight connection handling for MCP servers."""

from abc import ABC, abstractmethod
from contextlib import AsyncExitStack
from typing import Any

from mcp import ClientSession, StdioServerParameters
from mcp.client.sse import sse_client
from mcp.client.stdio import stdio_client
from mcp.client.streamable_http import streamablehttp_client


class MCPConnection(ABC):
    """Base class for MCP server connections."""

    def __init__(self):
        self.session = None
        self._stack = None

    @abstractmethod
    def _create_context(self):
        """Create the connection context based on connection type."""

    async def __aenter__(self):
        """Initialize MCP server connection."""
        self._stack = AsyncExitStack()
        await self._stack.__aenter__()

        try:
            ctx = self._create_context()
            result = await self._stack.enter_async_context(ctx)

            if len(result) == 2:
                read, write = result
            elif len(result) == 3:
                read, write, _ = result
            else:
                raise ValueError(f"Unexpected context result: {result}")

            session_ctx = ClientSession(read, write)
            self.session = await self._stack.enter_async_context(session_ctx)
            await self.session.initialize()
            return self
        except BaseException:
            await self._stack.__aexit__(None, None, None)
            raise

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        """Clean up MCP server connection resources."""
        if self._stack:
            await self._stack.__aexit__(exc_type, exc_val, exc_tb)
        self.session = None
        self._stack = None

    async def list_tools(self) -> list[dict[str, Any]]:
        """Retrieve available tools from the MCP server."""
        response = await self.session.list_tools()
        return [
            {
                "name": tool.name,
                "description": tool.description,
                "input_schema": tool.inputSchema,
            }
            for tool in response.tools
        ]

    async def call_tool(self, tool_name: str, arguments: dict[str, Any]) -> Any:
        """Call a tool on the MCP server with provided arguments."""
        result = await self.session.call_tool(tool_name, arguments=arguments)
        return result.content


class MCPConnectionStdio(MCPConnection):
    """MCP connection using standard input/output."""

    def __init__(self, command: str, args: list[str] = None, env: dict[str, str] = None):
        super().__init__()
        self.command = command
        self.args = args or []
        self.env = env

    def _create_context(self):
        return stdio_client(
            StdioServerParameters(command=self.command, args=self.args, env=self.env)
        )


class MCPConnectionSSE(MCPConnection):
    """MCP connection using Server-Sent Events."""

    def __init__(self, url: str, headers: dict[str, str] = None):
        super().__init__()
        self.url = url
        self.headers = headers or {}

    def _create_context(self):
        return sse_client(url=self.url, headers=self.headers)


class MCPConnectionHTTP(MCPConnection):
    """MCP connection using Streamable HTTP."""

    def __init__(self, url: str, headers: dict[str, str] = None):
        super().__init__()
        self.url = url
        self.headers = headers or {}

    def _create_context(self):
        return streamablehttp_client(url=self.url, headers=self.headers)


def create_connection(
    transport: str,
    command: str = None,
    args: list[str] = None,
    env: dict[str, str] = None,
    url: str = None,
    headers: dict[str, str] = None,
) -> MCPConnection:
    """Factory function to create the appropriate MCP connection.

    Args:
        transport: Connection type ("stdio", "sse", or "http")
        command: Command to run (stdio only)
        args: Command arguments (stdio only)
        env: Environment variables (stdio only)
        url: Server URL (sse and http only)
        headers: HTTP headers (sse and http only)

    Returns:
        MCPConnection instance
    """
    transport = transport.lower()

    if transport == "stdio":
        if not command:
            raise ValueError("Command is required for stdio transport")
        return MCPConnectionStdio(command=command, args=args, env=env)

    elif transport == "sse":
        if not url:
            raise ValueError("URL is required for sse transport")
        return MCPConnectionSSE(url=url, headers=headers)

    elif transport in ["http", "streamable_http", "streamable-http"]:
        if not url:
            raise ValueError("URL is required for http transport")
        return MCPConnectionHTTP(url=url, headers=headers)

    else:
        raise ValueError(f"Unsupported transport type: {transport}. Use 'stdio', 'sse', or 'http'")

FILE:scripts/evaluation.py
"""MCP Server Evaluation Harness

This script evaluates MCP servers by running test questions against them using Claude.
"""

import argparse
import asyncio
import json
import re
import sys
import time
import traceback
import xml.etree.ElementTree as ET
from pathlib import Path
from typing import Any

from anthropic import Anthropic

from connections import create_connection

EVALUATION_PROMPT = """You are an AI assistant with access to tools.

When given a task, you MUST:
1. Use the available tools to complete the task
2. Provide summary of each step in your approach, wrapped in <summary> tags
3. Provide feedback on the tools provided, wrapped in <feedback> tags
4. Provide your final response, wrapped in <response> tags

Summary Requirements:
- In your <summary> tags, you must explain:
  - The steps you took to complete the task
  - Which tools you used, in what order, and why
  - The inputs you provided to each tool
  - The outputs you received from each tool
  - A summary for how you arrived at the response

Feedback Requirements:
- In your <feedback> tags, provide constructive feedback on the tools:
  - Comment on tool names: Are they clear and descriptive?
  - Comment on input parameters: Are they well-documented? Are required vs optional parameters clear?
  - Comment on descriptions: Do they accurately describe what the tool does?
  - Comment on any errors encountered during tool usage: Did the tool fail to execute? Did the tool return too many tokens?
  - Identify specific areas for improvement and explain WHY they would help
  - Be specific and actionable in your suggestions

Response Requirements:
- Your response should be concise and directly address what was asked
- Always wrap your final response in <response> tags
- If you cannot solve the task return <response>NOT_FOUND</response>
- For numeric responses, provide just the number
- For IDs, provide just the ID
- For names or text, provide the exact text requested
- Your response should go last"""


def parse_evaluation_file(file_path: Path) -> list[dict[str, Any]]:
    """Parse XML evaluation file with qa_pair elements."""
    try:
        tree = ET.parse(file_path)
        root = tree.getroot()
        evaluations = []

        for qa_pair in root.findall(".//qa_pair"):
            question_elem = qa_pair.find("question")
            answer_elem = qa_pair.find("answer")

            if question_elem is not None and answer_elem is not None:
                evaluations.append({
                    "question": (question_elem.text or "").strip(),
                    "answer": (answer_elem.text or "").strip(),
                })

        return evaluations
    except Exception as e:
        print(f"Error parsing evaluation file {file_path}: {e}")
        return []


def extract_xml_content(text: str, tag: str) -> str | None:
    """Extract content from XML tags."""
    pattern = rf"<{tag}>(.*?)</{tag}>"
    matches = re.findall(pattern, text, re.DOTALL)
    return matches[-1].strip() if matches else None


async def agent_loop(
    client: Anthropic,
    model: str,
    question: str,
    tools: list[dict[str, Any]],
    connection: Any,
) -> tuple[str, dict[str, Any]]:
    """Run the agent loop with MCP tools."""
    messages = [{"role": "user", "content": question}]

    response = await asyncio.to_thread(
        client.messages.create,
        model=model,
        max_tokens=4096,
        system=EVALUATION_PROMPT,
        messages=messages,
        tools=tools,
    )

    messages.append({"role": "assistant", "content": response.content})

    tool_metrics = {}

    while response.stop_reason == "tool_use":
        tool_use = next(block for block in response.content if block.type == "tool_use")
        tool_name = tool_use.name
        tool_input = tool_use.input

        tool_start_ts = time.time()
        try:
            tool_result = await connection.call_tool(tool_name, tool_input)
            tool_response = json.dumps(tool_result) if isinstance(tool_result, (dict, list)) else str(tool_result)
        except Exception as e:
            tool_response = f"Error executing tool {tool_name}: {str(e)}\n"
            tool_response += traceback.format_exc()
        tool_duration = time.time() - tool_start_ts

        if tool_name not in tool_metrics:
            tool_metrics[tool_name] = {"count": 0, "durations": []}
        tool_metrics[tool_name]["count"] += 1
        tool_metrics[tool_name]["durations"].append(tool_duration)

        messages.append({
            "role": "user",
            "content": [{
                "type": "tool_result",
                "tool_use_id": tool_use.id,
                "content": tool_response,
            }]
        })

        response = await asyncio.to_thread(
            client.messages.create,
            model=model,
            max_tokens=4096,
            system=EVALUATION_PROMPT,
            messages=messages,
            tools=tools,
        )
        messages.append({"role": "assistant", "content": response.content})

    response_text = next(
        (block.text for block in response.content if hasattr(block, "text")),
        None,
    )
    return response_text, tool_metrics


async def evaluate_single_task(
    client: Anthropic,
    model: str,
    qa_pair: dict[str, Any],
    tools: list[dict[str, Any]],
    connection: Any,
    task_index: int,
) -> dict[str, Any]:
    """Evaluate a single QA pair with the given tools."""
    start_time = time.time()

    print(f"Task {task_index + 1}: Running task with question: {qa_pair['question']}")
    response, tool_metrics = await agent_loop(client, model, qa_pair["question"], tools, connection)

    response_value = extract_xml_content(response, "response")
    summary = extract_xml_content(response, "summary")
    feedback = extract_xml_content(response, "feedback")

    duration_seconds = time.time() - start_time

    return {
        "question": qa_pair["question"],
        "expected": qa_pair["answer"],
        "actual": response_value,
        "score": int(response_value == qa_pair["answer"]) if response_value else 0,
        "total_duration": duration_seconds,
        "tool_calls": tool_metrics,
        "num_tool_calls": sum(len(metrics["durations"]) for metrics in tool_metrics.values()),
        "summary": summary,
        "feedback": feedback,
    }


REPORT_HEADER = """
# Evaluation Report

## Summary

- **Accuracy**: {correct}/{total} ({accuracy:.1f}%)
- **Average Task Duration**: {average_duration_s:.2f}s
- **Average Tool Calls per Task**: {average_tool_calls:.2f}
- **Total Tool Calls**: {total_tool_calls}

---
"""

TASK_TEMPLATE = """
### Task {task_num}

**Question**: {question}
**Ground Truth Answer**: `{expected_answer}`
**Actual Answer**: `{actual_answer}`
**Correct**: {correct_indicator}
**Duration**: {total_duration:.2f}s
**Tool Calls**: {tool_calls}

**Summary**
{summary}

**Feedback**
{feedback}

---
"""


async def run_evaluation(
    eval_path: Path,
    connection: Any,
    model: str = "claude-3-7-sonnet-20250219",
) -> str:
    """Run evaluation with MCP server tools."""
    print("🚀 Starting Evaluation")

    client = Anthropic()

    tools = await connection.list_tools()
    print(f"📋 Loaded {len(tools)} tools from MCP server")

    qa_pairs = parse_evaluation_file(eval_path)
    print(f"📋 Loaded {len(qa_pairs)} evaluation tasks")

    results = []
    for i, qa_pair in enumerate(qa_pairs):
        print(f"Processing task {i + 1}/{len(qa_pairs)}")
        result = await evaluate_single_task(client, model, qa_pair, tools, connection, i)
        results.append(result)

    correct = sum(r["score"] for r in results)
    accuracy = (correct / len(results)) * 100 if results else 0
    average_duration_s = sum(r["total_duration"] for r in results) / len(results) if results else 0
    average_tool_calls = sum(r["num_tool_calls"] for r in results) / len(results) if results else 0
    total_tool_calls = sum(r["num_tool_calls"] for r in results)

    report = REPORT_HEADER.format(
        correct=correct,
        total=len(results),
        accuracy=accuracy,
        average_duration_s=average_duration_s,
        average_tool_calls=average_tool_calls,
        total_tool_calls=total_tool_calls,
    )

    report += "".join([
        TASK_TEMPLATE.format(
            task_num=i + 1,
            question=qa_pair["question"],
            expected_answer=qa_pair["answer"],
            actual_answer=result["actual"] or "N/A",
            correct_indicator="✅" if result["score"] else "❌",
            total_duration=result["total_duration"],
            tool_calls=json.dumps(result["tool_calls"], indent=2),
            summary=result["summary"] or "N/A",
            feedback=result["feedback"] or "N/A",
        )
        for i, (qa_pair, result) in enumerate(zip(qa_pairs, results))
    ])

    return report


def parse_headers(header_list: list[str]) -> dict[str, str]:
    """Parse header strings in format 'Key: Value' into a dictionary."""
    headers = {}
    if not header_list:
        return headers

    for header in header_list:
        if ":" in header:
            key, value = header.split(":", 1)
            headers[key.strip()] = value.strip()
        else:
            print(f"Warning: Ignoring malformed header: {header}")
    return headers


def parse_env_vars(env_list: list[str]) -> dict[str, str]:
    """Parse environment variable strings in format 'KEY=VALUE' into a dictionary."""
    env = {}
    if not env_list:
        return env

    for env_var in env_list:
        if "=" in env_var:
            key, value = env_var.split("=", 1)
            env[key.strip()] = value.strip()
        else:
            print(f"Warning: Ignoring malformed environment variable: {env_var}")
    return env


async def main():
    parser = argparse.ArgumentParser(
        description="Evaluate MCP servers using test questions",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog="""
Examples:
  # Evaluate a local stdio MCP server
  python evaluation.py -t stdio -c python -a my_server.py eval.xml

  # Evaluate an SSE MCP server
  python evaluation.py -t sse -u https://example.com/mcp -H "Authorization: Bearer token" eval.xml

  # Evaluate an HTTP MCP server with custom model
  python evaluation.py -t http -u https://example.com/mcp -m claude-3-5-sonnet-20241022 eval.xml
        """,
    )

    parser.add_argument("eval_file", type=Path, help="Path to evaluation XML file")
    parser.add_argument("-t", "--transport", choices=["stdio", "sse", "http"], default="stdio", help="Transport type (default: stdio)")
    parser.add_argument("-m", "--model", default="claude-3-7-sonnet-20250219", help="Claude model to use (default: claude-3-7-sonnet-20250219)")

    stdio_group = parser.add_argument_group("stdio options")
    stdio_group.add_argument("-c", "--command", help="Command to run MCP server (stdio only)")
    stdio_group.add_argument("-a", "--args", nargs="+", help="Arguments for the command (stdio only)")
    stdio_group.add_argument("-e", "--env", nargs="+", help="Environment variables in KEY=VALUE format (stdio only)")

    remote_group = parser.add_argument_group("sse/http options")
    remote_group.add_argument("-u", "--url", help="MCP server URL (sse/http only)")
    remote_group.add_argument("-H", "--header", nargs="+", dest="headers", help="HTTP headers in 'Key: Value' format (sse/http only)")

    parser.add_argument("-o", "--output", type=Path, help="Output file for evaluation report (default: stdout)")

    args = parser.parse_args()

    if not args.eval_file.exists():
        print(f"Error: Evaluation file not found: {args.eval_file}")
        sys.exit(1)

    headers = parse_headers(args.headers) if args.headers else None
    env_vars = parse_env_vars(args.env) if args.env else None

    try:
        connection = create_connection(
            transport=args.transport,
            command=args.command,
            args=args.args,
            env=env_vars,
            url=args.url,
            headers=headers,
        )
    except ValueError as e:
        print(f"Error: {e}")
        sys.exit(1)

    print(f"🔗 Connecting to MCP server via {args.transport}...")

    async with connection:
        print("✅ Connected successfully")
        report = await run_evaluation(args.eval_file, connection, args.model)

        if args.output:
            args.output.write_text(report)
            print(f"\n✅ Report saved to {args.output}")
        else:
            print("\n" + report)


if __name__ == "__main__":
    asyncio.run(main())

FILE:scripts/example_evaluation.xml
<evaluation>
   <qa_pair>
      <question>Calculate the compound interest on $10,000 invested at 5% annual interest rate, compounded monthly for 3 years. What is the final amount in dollars (rounded to 2 decimal places)?</question>
      <answer>11614.72</answer>
   </qa_pair>
   <qa_pair>
      <question>A projectile is launched at a 45-degree angle with an initial velocity of 50 m/s. Calculate the total distance (in meters) it has traveled from the launch point after 2 seconds, assuming g=9.8 m/s². Round to 2 decimal places.</question>
      <answer>87.25</answer>
   </qa_pair>
   <qa_pair>
      <question>A sphere has a volume of 500 cubic meters. Calculate its surface area in square meters. Round to 2 decimal places.</question>
      <answer>304.65</answer>
   </qa_pair>
   <qa_pair>
      <question>Calculate the population standard deviation of this dataset: [12, 15, 18, 22, 25, 30, 35]. Round to 2 decimal places.</question>
      <answer>7.61</answer>
   </qa_pair>
   <qa_pair>
      <question>Calculate the pH of a solution with a hydrogen ion concentration of 3.5 × 10^-5 M. Round to 2 decimal places.</question>
      <answer>4.46</answer>
   </qa_pair>
</evaluation>

FILE:scripts/requirements.txt
anthropic>=0.39.0
mcp>=1.1.0

FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/mcp-builder
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: internal-comms
description: A set of resources to help me write all kinds of internal communications, using the formats that my company likes to use. Claude should use this skill whenever asked to write some sort of internal communications (status reports, leadership updates, 3P updates, company newsletters, FAQs, incident reports, project updates, etc.).
license: Complete terms in LICENSE.txt
---

## When to use this skill
To write internal communications, use this skill for:
- 3P updates (Progress, Plans, Problems)
- Company newsletters
- FAQ responses
- Status reports
- Leadership updates
- Project updates
- Incident reports

## How to use this skill

To write any internal communication:

1. **Identify the communication type** from the request
2. **Load the appropriate guideline file** from the `examples/` directory:
    - `examples/3p-updates.md` - For Progress/Plans/Problems team updates
    - `examples/company-newsletter.md` - For company-wide newsletters
    - `examples/faq-answers.md` - For answering frequently asked questions
    - `examples/general-comms.md` - For anything else that doesn't explicitly match one of the above
3. **Follow the specific instructions** in that file for formatting, tone, and content gathering

If the communication type doesn't match any existing guideline, ask for clarification or more context about the desired format.

## Keywords
3P updates, company newsletter, company comms, weekly update, faqs, common questions, updates, internal comms

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:examples/3p-updates.md
## Instructions
You are being asked to write a 3P update. 3P updates stand for "Progress, Plans, Problems." The main audience is for executives, leadership, other teammates, etc. They're meant to be very succinct and to-the-point: think something you can read in 30-60sec or less. They're also for people with some, but not a lot of context on what the team does.

3Ps can cover a team of any size, ranging all the way up to the entire company. The bigger the team, the less granular the tasks should be. For example, "mobile team" might have "shipped feature" or "fixed bugs," whereas the company might have really meaty 3Ps, like "hired 20 new people" or "closed 10 new deals." 

They represent the work of the team across a time period, almost always one week. They include three sections:
1) Progress: what the team has accomplished over the next time period. Focus mainly on things shipped, milestones achieved, tasks created, etc.
2) Plans: what the team plans to do over the next time period. Focus on what things are top-of-mind, really high priority, etc. for the team.
3) Problems: anything that is slowing the team down. This could be things like too few people, bugs or blockers that are preventing the team from moving forward, some deal that fell through, etc.

Before writing them, make sure that you know the team name. If it's not specified, you can ask explicitly what the team name you're writing for is.


## Tools Available
Whenever possible, try to pull from available sources to get the information you need:
- Slack: posts from team members with their updates - ideally look for posts in large channels with lots of reactions
- Google Drive: docs written from critical team members with lots of views
- Email: emails with lots of responses of lots of content that seems relevant
- Calendar: non-recurring meetings that have a lot of importance, like product reviews, etc.


Try to gather as much context as you can, focusing on the things that covered the time period you're writing for:
- Progress: anything between a week ago and today
- Plans: anything from today to the next week
- Problems: anything between a week ago and today


If you don't have access, you can ask the user for things they want to cover. They might also include these things to you directly, in which case you're mostly just formatting for this particular format.

## Workflow

1. **Clarify scope**: Confirm the team name and time period (usually past week for Progress/Problems, next
week for Plans)
2. **Gather information**: Use available tools or ask the user directly
3. **Draft the update**: Follow the strict formatting guidelines
4. **Review**: Ensure it's concise (30-60 seconds to read) and data-driven

## Formatting

The format is always the same, very strict formatting. Never use any formatting other than this. Pick an emoji that is fun and captures the vibe of the team and update.

[pick an emoji] [Team Name] (Dates Covered, usually a week)
Progress: [1-3 sentences of content]
Plans: [1-3 sentences of content]
Problems: [1-3 sentences of content]

Each section should be no more than 1-3 sentences: clear, to the point. It should be data-driven, and generally include metrics where possible. The tone should be very matter-of-fact, not super prose-heavy.
FILE:examples/company-newsletter.md
## Instructions
You are being asked to write a company-wide newsletter update. You are meant to summarize the past week/month of a company in the form of a newsletter that the entire company will read. It should be maybe ~20-25 bullet points long. It will be sent via Slack and email, so make it consumable for that.

Ideally it includes the following attributes:
- Lots of links: pulling documents from Google Drive that are very relevant, linking to prominent Slack messages in announce channels and from executives, perhgaps referencing emails that went company-wide, highlighting significant things that have happened in the company.
- Short and to-the-point: each bullet should probably be no longer than ~1-2 sentences
- Use the "we" tense, as you are part of the company. Many of the bullets should say "we did this" or "we did that"

## Tools to use
If you have access to the following tools, please try to use them. If not, you can also let the user know directly that their responses would be better if they gave them access.

- Slack: look for messages in channels with lots of people, with lots of reactions or lots of responses within the thread
- Email: look for things from executives that discuss company-wide announcements
- Calendar: if there were meetings with large attendee lists, particularly things like All-Hands meetings, big company announcements, etc. If there were documents attached to those meetings, those are great links to include.
- Documents: if there were new docs published in the last week or two that got a lot of attention, you can link them. These should be things like company-wide vision docs, plans for the upcoming quarter or half, things authored by critical executives, etc.
- External press: if you see references to articles or press we've received over the past week, that could be really cool too.

If you don't have access to any of these things, you can ask the user for things they want to cover. In this case, you'll mostly just be polishing up and fitting to this format more directly.

## Sections
The company is pretty big: 1000+ people. There are a variety of different teams and initiatives going on across the company. To make sure the update works well, try breaking it into sections of similar things. You might break into clusters like {product development, go to market, finance} or {recruiting, execution, vision}, or {external news, internal news} etc. Try to make sure the different areas of the company are highlighted well.

## Prioritization
Focus on:
- Company-wide impact (not team-specific details)
- Announcements from leadership
- Major milestones and achievements
- Information that affects most employees
- External recognition or press

Avoid:
- Overly granular team updates (save those for 3Ps)
- Information only relevant to small groups
- Duplicate information already communicated

## Example Formats

:megaphone: Company Announcements
- Announcement 1
- Announcement 2
- Announcement 3

:dart: Progress on Priorities
- Area 1
    - Sub-area 1
    - Sub-area 2
    - Sub-area 3
- Area 2
    - Sub-area 1
    - Sub-area 2
    - Sub-area 3
- Area 3
    - Sub-area 1
    - Sub-area 2
    - Sub-area 3

:pillar: Leadership Updates
- Post 1
- Post 2
- Post 3

:thread: Social Updates
- Update 1
- Update 2
- Update 3

FILE:examples/faq-answers.md
## Instructions
You are an assistant for answering questions that are being asked across the company. Every week, there are lots of questions that get asked across the company, and your goal is to try to summarize what those questions are. We want our company to be well-informed and on the same page, so your job is to produce a set of frequently asked questions that our employees are asking and attempt to answer them. Your singular job is to do two things:

- Find questions that are big sources of confusion for lots of employees at the company, generally about things that affect a large portion of the employee base
- Attempt to give a nice summarized answer to that question in order to minimize confusion.

Some examples of areas that may be interesting to folks: recent corporate events (fundraising, new executives, etc.), upcoming launches, hiring progress, changes to vision or focus, etc.


## Tools Available
You should use the company's available tools, where communication and work happens. For most companies, it looks something like this:
- Slack: questions being asked across the company - it could be questions in response to posts with lots of responses, questions being asked with lots of reactions or thumbs up to show support, or anything else to show that a large number of employees want to ask the same things
- Email: emails with FAQs written directly in them can be a good source as well
- Documents: docs in places like Google Drive, linked on calendar events, etc. can also be a good source of FAQs, either directly added or inferred based on the contents of the doc

## Formatting
The formatting should be pretty basic:

- *Question*: [insert question - 1 sentence]
- *Answer*: [insert answer - 1-2 sentence]

## Guidance
Make sure you're being holistic in your questions. Don't focus too much on just the user in question or the team they are a part of, but try to capture the entire company. Try to be as holistic as you can in reading all the tools available, producing responses that are relevant to all at the company.

## Answer Guidelines
- Base answers on official company communications when possible
- If information is uncertain, indicate that clearly
- Link to authoritative sources (docs, announcements, emails)
- Keep tone professional but approachable
- Flag if a question requires executive input or official response
FILE:examples/general-comms.md
  ## Instructions
  You are being asked to write internal company communication that doesn't fit into the standard formats (3P
  updates, newsletters, or FAQs).

  Before proceeding:
  1. Ask the user about their target audience
  2. Understand the communication's purpose
  3. Clarify the desired tone (formal, casual, urgent, informational)
  4. Confirm any specific formatting requirements

  Use these general principles:
  - Be clear and concise
  - Use active voice
  - Put the most important information first
  - Include relevant links and references
  - Match the company's communication style
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/internal-comms
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: frontend-design
description: Guidance for distinctive, intentional visual design when building new UI or reshaping an existing one. Helps with aesthetic direction, typography, and making choices that don't read as templated defaults.
license: Complete terms in LICENSE.txt
---

# Frontend Design

Approach this as the design lead at a small studio known for giving every client a visual identity that could not be mistaken for anyone else's. This client has already rejected proposals that felt templated, and is paying for a distinctive point of view: make deliberate, opinionated choices about palette, typography, and layout that are specific to this brief, and take one real aesthetic risk you can justify.

## Ground it in the subject

If the brief does not pin down what the product or subject is, pin it yourself before designing: name one concrete subject, its audience, and the page's single job, and state your choice. If there's any information in your memory about the human's preferences, context about what they're building, or designs you've made before – use that as a hint. The subject's own world, its materials, instruments, artifacts, and vernacular, is where distinctive choices come from. Build with the brief's real content and subject matter throughout.

## Design principles

For web designs, the hero is a thesis. Open with the most characteristic thing in the subject's world, in whatever form makes sense for it: a headline, an image, an animation, a live demo, an interactive moment. Be deliberate with your choice: a big number with a small label, supporting stats, and a gradient accent is the template answer, only use if that's truly the best option.

Typography carries the personality of the page. Pair the display and body faces deliberately, not the same families you would reach for on any other project, and set a clear type scale with intentional weights, widths, and spacing. Make the type treatment itself a memorable part of the design, not a neutral delivery vehicle for the content.

Structure is information. Structural devices, numbering, eyebrows, dividers, labels, should encode something true about the content, not decorate it. Many generic designs use numbered markers (01 / 02 / 03), but that's only appropriate if the content actually is a sequence - like a real process or a typed timeline where order carries information the reader needs. Question if choices like numbered markers actually make sense before incorporating them.

Leverage motion deliberately. Think about where and if animation can serve the subject: a page-load sequence, a scroll-triggered reveal, hover micro-interactions, ambient atmosphere. An orchestrated moment usually lands harder than scattered effects; choose what the direction calls for. However, sometimes less is more, and extra animation contributes to the feeling that the design is AI-generated.

Match complexity to the vision. Maximalist directions need elaborate execution; minimal directions need precision in spacing, type, and detail. Elegance is executing the chosen vision well.

Consider written content carefully. Often a design brief may not contain real content, and it's up to you to come up with copy. Copy can make a design feel as templated as the design itself. See the below section on writing for more guidance.

## Process: brainstorm, explore, plan, critique, build, critique again

For calibration: AI-generated design right now clusters around three looks: (1) a warm cream background (near #F4F1EA) with a high-contrast serif display and a terracotta accent; (2) a near-black background with a single bright acid-green or vermilion accent; (3) a broadsheet-style layout with hairline rules, zero border-radius, and dense newspaper-like columns. All three are legitimate for some briefs, but they are defaults rather than choices, and they appear regardless of subject. Where the brief pins down a visual direction, follow it exactly — the brief's own words always win, including when it asks for one of these looks. Where it leaves an axis free, don't spend that freedom on one of these defaults. Just like a human designer who's hired, there's often a careful balance between doing what you're good at and taking each project as a chance to experiment and learn.

Work in two passes. First, brainstorm a short design plan based on the human's design brief: create a compact token system with color, type, layout, and signature. Color: describe the palette as 4–6 named hex values. Type: the typefaces for 2+ roles (a characterful display face that's used with restraint, a complementary body face, and a utility face for captions or data if needed). Layout: a layout concept, using one-sentence prose descriptions and ASCII wireframes to ideate and compare. Signature: the single unique element this page will be remembered by that embodies the brief in an appropriate way.

Then review that plan against the brief before building: if any part of it reads like the generic default you would produce for any similar page (work through a similar prompt to see if you arrive somewhere similar) rather than a choice made for this specific brief — revise that part, say what you changed and why. Only after you've confirmed the relative uniqueness of your design plan should you start to write the code, following the revised plan exactly and deriving every color and type decision from it.

When writing the code, be careful of structuring your CSS selector specificities. It's easy to generate CSS classes that cancel each other out (especially with a type-based selector like .section and a element-based selector like .cta). This can happen often with paddings/margins between sections.

Try to do a lot of this planning and iteration in your thinking, and only show ideas to the user when you have higher confidence it'll delight them.

## Restraint and self-critique

Spend your boldness in one place. Let the signature element be the one memorable thing, keep everything around it quiet and disciplined, and cut any decoration that does not serve the brief. Not taking a risk can be a risk itself! Build to a quality floor without announcing it: responsive down to mobile, visible keyboard focus, reduced motion respected. Critique your own work as you build, taking screenshots if your environment supports it – a picture is worth 1000 tokens. Consider Chanel's advice: before leaving the house, take a look in the mirror and remove one accessory. Human creators have memory and always try to do something new, so if you have a space to quickly jot down notes about what you've tried, it can help you in future passes.

## More on writing in design

Words appear in a design for one reason: to make it easier to understand, and therefore easier to use. They are design material, not decoration. Bring the same intentionality to copy that you would bring to spacing and color. Before writing anything, ask what the design needs to say, and how it can best be said to help the person navigate the experience.

Write from the end user's side of the screen. Name things by what people control and recognize, never by how the system is built. A person manages notifications, not webhook config. Describe what something does in plain terms rather than selling it. Being specific is always better than being clever.

Use active voice as default. A control should say exactly what happens when it's used: "Save changes," not "Submit." An action keeps the same name through the whole flow, so the button that says "Publish" produces a toast that says "Published." The vocabulary of an interface is the signposting for someone navigating the product. Cohesion and consistency are how people learn their way around.

Treat failure and emptiness as moments for direction, not mood. Explain what went wrong and how to fix it, in the interface's voice rather than a person's. Errors don't apologize, and they are never vague about what happened. An empty screen is an invitation to act.

Keep the register conversational and tuned: plain verbs, sentence case, no filler, with tone matched to the brand and the audience. Let each element do exactly one job. A label labels, an example demonstrates, and nothing quietly does double duty.

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/frontend-design
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: claude-api
description: |-
  Reference for the Claude API / Anthropic SDK — model ids, pricing, params, streaming, tool use, MCP, agents, caching, token counting, model migration.
  TRIGGER — read BEFORE opening the target file; don't skip because it "looks like a one-liner" — whenever: the prompt names Claude/Anthropic in any form (Claude, Anthropic, Fable, Opus, Sonnet, Haiku, `anthropic`, `@anthropic-ai`, `claude-*`, `us.anthropic.*`, `[1m]`); the user asks about an LLM (pricing/model choice/limits/caching) — never answer from memory; OR the task is LLM-shaped with provider unstated (agent/MCP/tool-definition/multi-agent/RAG/LLM-judge/computer-use; generate/summarize/extract/classify/rewrite/converse over NL; debugging refusals/cutoffs/streaming/tool-calls/tokens).
  SKIP only when another provider is being worked on (overrides all triggers): OpenAI/GPT/Gemini/Llama/Mistral/Cohere/Ollama named in the query; OR `grep -rE 'openai|langchain_openai|google.generativeai|genai|mistralai|cohere|ollama'` over the project hits (run this grep FIRST if no provider named — don't Read the file).
license: Complete terms in LICENSE.txt
---

# Building LLM-Powered Applications with Claude

This skill helps you build LLM-powered applications with Claude. Choose the right surface based on your needs, detect the project language, then read the relevant language-specific documentation.

## Before You Start

Scan the target file (or, if no target file, the prompt and project) for non-Anthropic provider markers — `import openai`, `from openai`, `langchain_openai`, `OpenAI(`, `gpt-4`, `gpt-5`, file names like `agent-openai.py` or `*-generic.py`, or any explicit instruction to keep the code provider-neutral. If you find any, stop and tell the user that this skill produces Claude/Anthropic SDK code; ask whether they want to switch the file to Claude or want a non-Claude implementation. Do not edit a non-Anthropic file with Anthropic SDK calls.

## Output Requirement

When the user asks you to add, modify, or implement a Claude feature, your code must call Claude through one of:

1. **The official Anthropic SDK** for the project's language (`anthropic`, `@anthropic-ai/sdk`, `com.anthropic.*`, etc.). This is the default whenever a supported SDK exists for the project.
2. **Raw HTTP** (`curl`, `requests`, `fetch`, `httpx`, etc.) — only when the user explicitly asks for cURL/REST/raw HTTP, the project is a shell/cURL project, or the language has no official SDK.

Never mix the two — don't reach for `requests`/`fetch` in a Python or TypeScript project just because it feels lighter. Never fall back to OpenAI-compatible shims.

**Never guess SDK usage.** Function names, class names, namespaces, method signatures, and import paths must come from explicit documentation — either the `{lang}/` files in this skill or the official SDK repositories or documentation links listed in `shared/live-sources.md`. If the binding you need is not explicitly documented in the skill files, WebFetch the relevant SDK repo from `shared/live-sources.md` before writing code. Do not infer Ruby/Java/Go/PHP/C# APIs from cURL shapes or from another language's SDK.

## Defaults

Unless the user requests otherwise:

For the Claude model version, please use Claude Opus 4.8, which you can access via the exact model string `claude-opus-4-8`. Please default to using adaptive thinking (`thinking: {type: "adaptive"}`) for anything remotely complicated. And finally, please default to streaming for any request that may involve long input, long output, or high `max_tokens` — it prevents hitting request timeouts. Use the SDK's `.get_final_message()` / `.finalMessage()` helper to get the complete response if you don't need to handle individual stream events

---

## Subcommands

If the User Request at the bottom of this prompt is a bare subcommand string (no prose), search every **Subcommands** table in this document — including any in sections appended below — and follow the matching Action column directly. This lets users invoke specific flows via `/claude-api <subcommand>`. If no table in the document matches, treat the request as normal prose.

| Subcommand | Action |
|---|---|
| `migrate` | Migrate existing Claude API code to a newer model. **Read `shared/model-migration.md` immediately** and follow it in order: Step 0 (confirm scope — ask which files/directories before any edit), Step 1 (classify each file), then the per-target breaking-changes section. Do not summarize the guide — execute it. If the user did not name a target model, ask which model to migrate to in the same turn as the scope question. |

---

## Language Detection

Before reading code examples, determine which language the user is working in:

1. **Look at project files** to infer the language:

   - `*.py`, `requirements.txt`, `pyproject.toml`, `setup.py`, `Pipfile` → **Python** — read from `python/`
   - `*.ts`, `*.tsx`, `package.json`, `tsconfig.json` → **TypeScript** — read from `typescript/`
   - `*.js`, `*.jsx` (no `.ts` files present) → **TypeScript** — JS uses the same SDK, read from `typescript/`
   - `*.java`, `pom.xml`, `build.gradle` → **Java** — read from `java/`
   - `*.kt`, `*.kts`, `build.gradle.kts` → **Java** — Kotlin uses the Java SDK, read from `java/`
   - `*.scala`, `build.sbt` → **Java** — Scala uses the Java SDK, read from `java/`
   - `*.go`, `go.mod` → **Go** — read from `go/`
   - `*.rb`, `Gemfile` → **Ruby** — read from `ruby/`
   - `*.cs`, `*.csproj` → **C#** — read from `csharp/`
   - `*.php`, `composer.json` → **PHP** — read from `php/`

2. **If multiple languages detected** (e.g., both Python and TypeScript files):

   - Check which language the user's current file or question relates to
   - If still ambiguous, ask: "I detected both Python and TypeScript files. Which language are you using for the Claude API integration?"

3. **If language can't be inferred** (empty project, no source files, or unsupported language):

   - Use AskUserQuestion with options: Python, TypeScript, Java, Go, Ruby, cURL/raw HTTP, C#, PHP
   - If AskUserQuestion is unavailable, default to Python examples and note: "Showing Python examples. Let me know if you need a different language."

4. **If unsupported language detected** (Rust, Swift, C++, Elixir, etc.):

   - Suggest cURL/raw HTTP examples from `curl/` and note that community SDKs may exist
   - Offer to show Python or TypeScript examples as reference implementations

5. **If user needs cURL/raw HTTP examples**, read from `curl/`.

### Language-Specific Feature Support

| Language   | Tool Runner | Managed Agents | Notes                                 |
| ---------- | ----------- | -------------- | ------------------------------------- |
| Python     | Yes (beta)  | Yes (beta)     | Full support — `@beta_tool` decorator |
| TypeScript | Yes (beta)  | Yes (beta)     | Full support — `betaZodTool` + Zod    |
| Java       | Yes (beta)  | Yes (beta)     | Beta tool use with annotated classes  |
| Go         | Yes (beta)  | Yes (beta)     | `BetaToolRunner` in `toolrunner` pkg  |
| Ruby       | Yes (beta)  | Yes (beta)     | `BaseTool` + `tool_runner` in beta    |
| C#         | Yes (beta)  | Yes (beta)     | `BetaToolRunner` + raw JSON schema    |
| PHP        | Yes (beta)  | Yes (beta)     | `BetaRunnableTool` + `toolRunner()`   |
| cURL       | N/A         | Yes (beta)     | Raw HTTP, no SDK features             |

> **Managed Agents code examples**: dedicated language-specific READMEs are provided for Python, TypeScript, Go, Ruby, PHP, Java, and cURL (`{lang}/managed-agents/README.md`, `curl/managed-agents.md`). Read your language's README plus the language-agnostic `shared/managed-agents-*.md` concept files. **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `agents.create` and pass it to every subsequent `sessions.create`; do not call `agents.create` in the request path. The Anthropic CLI (`ant`) is one convenient way to create agents and environments from version-controlled YAML — see `shared/anthropic-cli.md`. If a binding you need isn't shown in the README, WebFetch the relevant entry from `shared/live-sources.md` rather than guess. C# has beta Managed Agents support via `client.Beta.Agents` and related namespaces.

---

## Which Surface Should I Use?

> **Start simple.** Default to the simplest tier that meets your needs. Single API calls and workflows handle most use cases — only reach for agents when the task genuinely requires open-ended, model-driven exploration.

| Use Case                                        | Tier            | Recommended Surface       | Why                                                          |
| ----------------------------------------------- | --------------- | ------------------------- | ------------------------------------------------------------ |
| Classification, summarization, extraction, Q&A  | Single LLM call | **Claude API**            | One request, one response                                    |
| Batch processing or embeddings                  | Single LLM call | **Claude API**            | Specialized endpoints                                        |
| Multi-step pipelines with code-controlled logic | Workflow        | **Claude API + tool use** | You orchestrate the loop                                     |
| Custom agent with your own tools                | Agent           | **Claude API + tool use** | Maximum flexibility                                          |
| Server-managed stateful agent with workspace    | Agent           | **Managed Agents**        | Anthropic runs the loop and hosts the tool-execution sandbox |
| Persisted, versioned agent configs              | Agent           | **Managed Agents**        | Agents are stored objects; sessions pin to a version         |
| Long-running multi-turn agent with file mounts  | Agent           | **Managed Agents**        | Per-session containers, SSE event stream, Skills + MCP       |

> **Note:** Managed Agents is the right choice when you want Anthropic to run the agent loop *and* host the container where tools execute — file ops, bash, code execution all run in the per-session workspace. If you want to host the compute yourself or run your own custom tool runtime, Claude API + tool use is the right choice — use the tool runner for automatic loop handling, or the manual loop for fine-grained control (approval gates, custom logging, conditional execution).

> **Cloud-provider access.** **Claude Platform on AWS** is Anthropic-operated with same-day API parity — Managed Agents and every feature in this skill work there, **except self-hosted sandboxes** (see `shared/claude-platform-on-aws.md`). **Amazon Bedrock**, **Google Vertex AI**, and **Microsoft Foundry** do **not** support Managed Agents or Anthropic server-side tools; use **Claude API + tool use** on those.

### Decision Tree

```
What does your application need?

0. Which provider?
   ├── First-party API or Claude Platform on AWS → continue (full surface available).
   └── Amazon Bedrock, Google Vertex AI, or Microsoft Foundry → Claude API (+ tool use for agents); Managed Agents not available there.

1. Single LLM call (classification, summarization, extraction, Q&A)
   └── Claude API — one request, one response

2. Do you want Anthropic to run the agent loop and host a per-session
   container where Claude executes tools (bash, file ops, code)?
   └── Yes → Managed Agents — server-managed sessions, persisted agent configs,
       SSE event stream, Skills + MCP, file mounts.
       Examples: "stateful coding agent with a workspace per task",
                 "long-running research agent that streams events to a UI",
                 "agent with persisted, versioned config used across many sessions"

3. Workflow (multi-step, code-orchestrated, with your own tools)
   └── Claude API with tool use — you control the loop

4. Open-ended agent (model decides its own trajectory, your own tools, you host the compute)
   └── Claude API agentic loop (maximum flexibility)
```

### Should I Build an Agent?

Before choosing the agent tier, check all four criteria:

- **Complexity** — Is the task multi-step and hard to fully specify in advance? (e.g., "turn this design doc into a PR" vs. "extract the title from this PDF")
- **Value** — Does the outcome justify higher cost and latency?
- **Viability** — Is Claude capable at this task type?
- **Cost of error** — Can errors be caught and recovered from? (tests, review, rollback)

If the answer is "no" to any of these, stay at a simpler tier (single call or workflow).

---

## Architecture

Everything goes through `POST /v1/messages`. Tools and output constraints are features of this single endpoint — not separate APIs.

**User-defined tools** — You define tools (via decorators, Zod schemas, or raw JSON), and the SDK's tool runner handles calling the API, executing your functions, and looping until Claude is done. For full control, you can write the loop manually.

**Server-side tools** — Anthropic-hosted tools that run on Anthropic's infrastructure. Code execution is fully server-side (declare it in `tools`, Claude runs code automatically). Computer use can be server-hosted or self-hosted.

**Structured outputs** — Constrains the Messages API response format (`output_config.format`) and/or tool parameter validation (`strict: true`). The recommended approach is `client.messages.parse()` which validates responses against your schema automatically. Note: the old `output_format` parameter is deprecated; use `output_config: {format: {...}}` on `messages.create()`.

**Supporting endpoints** — Batches (`POST /v1/messages/batches`), Files (`POST /v1/files`), Token Counting (`POST /v1/messages/count_tokens` — see `shared/token-counting.md`), and Models (`GET /v1/models`, `GET /v1/models/{id}` — live capability/context-window discovery) feed into or support Messages API requests.

---

## Current Models (cached: 2026-06-04)

| Model             | Model ID            | Context        | Input $/1M | Output $/1M |
| ----------------- | ------------------- | -------------- | ---------- | ----------- |
| Claude Fable 5    | `claude-fable-5`      | 1M             | $10.00     | $50.00      |
| Claude Mythos 5 (Project Glasswing only) | `claude-mythos-5` | 1M | $10.00     | $50.00      |
| Claude Opus 4.8   | `claude-opus-4-8`   | 1M             | $5.00      | $25.00      |
| Claude Opus 4.7   | `claude-opus-4-7`   | 1M             | $5.00      | $25.00      |
| Claude Opus 4.6   | `claude-opus-4-6`   | 1M             | $5.00      | $25.00      |
| Claude Sonnet 4.6 | `claude-sonnet-4-6` | 1M             | $3.00      | $15.00      |
| Claude Haiku 4.5  | `claude-haiku-4-5`  | 200K           | $1.00      | $5.00       |

**ALWAYS use `claude-opus-4-8` unless the user explicitly names a different model.** This is non-negotiable. Do not use `claude-sonnet-4-6`, `claude-sonnet-4-5`, or any other model unless the user literally says "use sonnet" or "use haiku". Never downgrade for cost — that's the user's decision, not yours. Use `claude-fable-5` only when the user explicitly asks for Claude Fable 5, "fable", or Anthropic's most capable model — it has different API behavior than the Opus family (see below) and pricing that exceeds Opus-tier.

### Claude Fable 5 (`claude-fable-5`) — most capable widely released model

Claude Fable 5 is Anthropic's most capable widely released model, for the most demanding reasoning and long-horizon agentic work. **Claude Mythos 5** (`claude-mythos-5`) offers the same capabilities, pricing, and API surface through Project Glasswing (participation is the only way to access it), succeeding the invitation-only Claude Mythos Preview (`claude-mythos-preview`) — everything below applies to both models. 1M context window (the maximum is also the default), 128K max output. Key API differences from Opus-tier — see `shared/model-migration.md` → Migrating to Claude Fable 5 for details:

- **Thinking is always on** — omit the `thinking` parameter entirely (or send `{type: "adaptive"}`). Any other explicit configuration is rejected: `{type: "disabled"}` and `{type: "enabled", budget_tokens: N}` both return a 400. Control depth with `output_config.effort` (supports `low` through `xhigh` and `max`).
- **Protected thinking = the raw chain of thought, not the summary** — responses carry regular `thinking` blocks (not `redacted_thinking`): `display: "summarized"` returns a readable summary, `"omitted"` (the default) leaves the `thinking` field as an empty string; the raw chain of thought is never exposed on any model. Replay rules: pass thinking blocks back exactly as received on the same model (including empty-text blocks — the API rejects *modified* blocks, not read ones); a **different** model **silently ignores** them (not an error), but ignored blocks still bill input tokens — strip them when switching models for good.
- **New tokenizer** — the same content tokenizes to roughly 30% more tokens than on Opus-tier models. Don't reuse token counts or `max_tokens` settings measured on other models; re-baseline with `count_tokens`.
- **`refusal` stop reason** — safety classifiers may decline a request (HTTP 200, `stop_reason: "refusal"`, with a `stop_details` category). A pre-output refusal has an empty `content` array and is not billed at all; a mid-stream refusal bills the already-streamed output — discard the partial output. Always check `stop_reason` before reading `content`. To retry on another model: the beta `fallbacks` parameter (Claude API and Claude Platform on AWS) retries server-side in one round trip; the GA SDKs' `BetaRefusalFallbackMiddleware` + `BetaFallbackState` handle client-side retry everywhere else (incl. Bedrock/Vertex); fallback credit refunds the cache-switch cost of client-side retries. See the migration guide's refusal section.
- **No assistant prefill** — same as the rest of the 4.6+ family.
- **30-day data retention required** — Claude Fable 5 is not available under zero data retention; requests from an org whose retention configuration doesn't meet the requirement return `400 invalid_request_error`.
- **Longer turns, different prompting** — single requests on hard tasks can run many minutes (plan timeouts/streaming/progress UX); effort sweeps should include low/medium for routine work; prompts written for prior models are often too prescriptive and reduce output quality. See `shared/model-migration.md` → Migrating to Claude Fable 5 → Behavioral shifts (prompt-tunable) for the recommended prompt snippets (anti-overplanning, no-tidying, grounded progress claims, boundaries, async sub-agents, memory, `send_to_user`).

**CRITICAL: Use only the exact model ID strings from the table above — they are complete as-is. Do not append date suffixes.** For example, use `claude-sonnet-4-6`, never `claude-sonnet-4-6-20251114` or any other date-suffixed variant you might recall from training data. If the user requests an older model not in the table (e.g., "opus 4.5", "sonnet 3.7"), read `shared/models.md` for the exact ID — do not construct one yourself.

A note: if any of the model strings above look unfamiliar to you, that's to be expected — that just means they were released after your training data cutoff. Rest assured they are real models; we wouldn't mess with you like that.

**Live capability lookup:** The table above is cached. When the user asks "what's the context window for X", "does X support vision/thinking/effort", or "which models support Y", query the Models API (`client.models.retrieve(id)` / `client.models.list()`) — see `shared/models.md` for the field reference and capability-filter examples.

---

## Thinking & Effort (Quick Reference)

**Fable 5 / Opus 4.8 / 4.7 — Adaptive thinking only:** Use `thinking: {type: "adaptive"}`. `thinking: {type: "enabled", budget_tokens: N}` returns a 400 — adaptive is the only on-mode. On Opus 4.8 and 4.7, `{type: "disabled"}` and omitting `thinking` both work; on Fable 5, an explicit `{type: "disabled"}` returns a 400 — omit the `thinking` param entirely instead. Sampling parameters (`temperature`, `top_p`, `top_k`) are also removed and will 400. Opus 4.8 keeps the same request surface as 4.7 (no new breaking changes) — see `shared/model-migration.md` → Migrating to Opus 4.8 for the behavioral re-tuning, and → Migrating to Opus 4.7 for the full breaking-change list when coming from 4.6 or earlier. Note: with `thinking` disabled, Opus 4.8 may write longer reasoning into the visible response — leave adaptive thinking on, or add a final-answer-only instruction (see the migration guide).
**Opus 4.6 — Adaptive thinking (recommended):** Use `thinking: {type: "adaptive"}`. Claude dynamically decides when and how much to think. No `budget_tokens` needed — `budget_tokens` is deprecated on Opus 4.6 and Sonnet 4.6 and should not be used for new code. Adaptive thinking also automatically enables interleaved thinking (no beta header needed). **When the user asks for "extended thinking", a "thinking budget", or `budget_tokens`: always use Fable 5, Opus 4.8, 4.7, or 4.6 with `thinking: {type: "adaptive"}`. The concept of a fixed token budget for thinking is deprecated — adaptive thinking replaces it. Do NOT use `budget_tokens` for new 4.6/4.7/4.8 code and do NOT switch to an older model.** *Gradual-migration carve-out:* `budget_tokens` is still functional on Opus 4.6 and Sonnet 4.6 as a transitional escape hatch — if you're migrating existing code and need a hard token ceiling before you've tuned `effort`, see `shared/model-migration.md` → Transitional escape hatch. Note: this carve-out does **not** apply to Fable 5, Opus 4.7 or 4.8 — `budget_tokens` is fully removed there.
**Effort parameter (GA, no beta header):** Controls thinking depth and overall token spend via `output_config: {effort: "low"|"medium"|"high"|"max"}` (inside `output_config`, not top-level). Default is `high` (equivalent to omitting it). `max` is supported on Fable 5, Opus 4.6 and later, and Sonnet 4.6 (not Haiku or earlier Sonnets). Opus 4.7 added `"xhigh"` (between `high` and `max`) — the best setting for most coding and agentic use cases on Fable 5 / Opus 4.7/4.8, and the default in Claude Code; use a minimum of `high` for most intelligence-sensitive work. Works on Fable 5, Opus 4.5, Opus 4.6, Opus 4.7, Opus 4.8, and Sonnet 4.6. Will error on Sonnet 4.5 / Haiku 4.5. On Fable 5, Opus 4.7 and 4.8, effort matters more than on any prior Opus — re-tune it when migrating, and run long-horizon/agentic tasks at `high`/`xhigh` with the full task spec given up front. Combine with adaptive thinking for the best cost-quality tradeoffs. Lower effort means fewer and more-consolidated tool calls, less preamble, and terser confirmations — `high` is often the sweet spot balancing quality and token efficiency; use `max` when correctness matters more than cost; use `low` for subagents or simple tasks.

**Thinking display — `"omitted"` by default on Fable 5 / Mythos 5 / Opus 4.8 / 4.7:** `display: "summarized"` returns a readable summary of the reasoning; `"omitted"` (the default on all four — a silent change from Opus 4.6, where it was `"summarized"`) streams `thinking` blocks with empty text. `display` controls visibility only — thinking happens and is billed the same under every setting; the raw chain of thought is never exposed on any model. If you stream reasoning to users, the default looks like a long pause before output — set `thinking: {type: "adaptive", display: "summarized"}` explicitly. (Independent of display, echo thinking blocks back unchanged when continuing on the same model; other models silently ignore them — see the migration guide.)

**Task Budgets (beta, Fable 5 / Opus 4.7 / 4.8):** `output_config: {task_budget: {type: "tokens", total: N}}` tells the model how many tokens it has for a full agentic loop — it sees a running countdown and self-moderates (minimum 20,000; beta header `task-budgets-2026-03-13`). Distinct from `max_tokens`, which is an enforced per-response ceiling the model is not aware of. See `shared/model-migration.md` → Task Budgets.

**Sonnet 4.6:** Supports adaptive thinking (`thinking: {type: "adaptive"}`). `budget_tokens` is deprecated on Sonnet 4.6 — use adaptive thinking instead.

**Older models (only if explicitly requested):** If the user specifically asks for Sonnet 4.5 or another older model, use `thinking: {type: "enabled", budget_tokens: N}`. `budget_tokens` must be less than `max_tokens` (minimum 1024). Never choose an older model just because the user mentions `budget_tokens` — use Opus 4.8 with adaptive thinking instead.

---

## Compaction (Quick Reference)

**Beta, Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6.** For long-running conversations that may exceed the 1M context window, enable server-side compaction. The API automatically summarizes earlier context when it approaches the trigger threshold (default: 150K tokens). Requires beta header `compact-2026-01-12`.

**Critical:** Append `response.content` (not just the text) back to your messages on every turn. Compaction blocks in the response must be preserved — the API uses them to replace the compacted history on the next request. Extracting only the text string and appending that will silently lose the compaction state.

See `{lang}/claude-api/README.md` (Compaction section) for code examples. Full docs via WebFetch in `shared/live-sources.md`.

---

## Prompt Caching (Quick Reference)

**Prefix match.** Any byte change anywhere in the prefix invalidates everything after it. Render order is `tools` → `system` → `messages`. Keep stable content first (frozen system prompt, deterministic tool list), put volatile content (timestamps, per-request IDs, varying questions) after the last `cache_control` breakpoint.

**Mid-conversation operator instructions** (beta header `mid-conversation-system-2026-04-07`, on supporting models): append `{"role": "system", ...}` to `messages[]` instead of editing top-level `system`. Preserves the cached history prefix and is the prompt-injection-safe operator channel. See `shared/prompt-caching.md` § Mid-conversation system messages.

**Top-level auto-caching** (`cache_control: {type: "ephemeral"}` on `messages.create()`) is the simplest option when you don't need fine-grained placement. Max 4 breakpoints per request. Minimum cacheable prefix is ~1024 tokens — shorter prefixes silently won't cache.

**Verify with `usage.cache_read_input_tokens`** — if it's zero across repeated requests, a silent invalidator is at work (`datetime.now()` in system prompt, unsorted JSON, varying tool set).

For placement patterns, architectural guidance, and the silent-invalidator audit checklist: read `shared/prompt-caching.md`. Language-specific syntax: `{lang}/claude-api/README.md` (Prompt Caching section).

---

## Managed Agents (Beta)

**Managed Agents** is a third surface: server-managed stateful agents with Anthropic-hosted tool execution. You create a persisted, versioned Agent config (`POST /v1/agents`), then start Sessions that reference it. Each session provisions a container as the agent's workspace — bash, file ops, and code execution run there; the agent loop itself runs on Anthropic's orchestration layer and acts on the container via tools. The session streams events; you send messages and tool results back.

**Managed Agents is available on the first-party API and Claude Platform on AWS.** It is **not** available on Amazon Bedrock, Google Vertex AI, or Microsoft Foundry — for agents there, use Claude API + tool use.

**Mandatory flow:** Agent (once) → Session (every run). `model`/`system`/`tools` live on the agent, never the session. See `shared/managed-agents-overview.md` for the full reading guide, beta headers, and pitfalls.

**Beta headers:** `managed-agents-2026-04-01` — the SDK sets this automatically for all `client.beta.{agents,environments,sessions,vaults,memory_stores,deployments,deployment_runs}.*` calls. Skills API uses `skills-2025-10-02` and Files API uses `files-api-2025-04-14`, but you don't need to explicitly pass those in for endpoints other than `/v1/skills` and `/v1/files`.

**Subcommands** — invoke directly with `/claude-api <subcommand>`:

| Subcommand | Action |
|---|---|
| `managed-agents-onboard` | Walk the user through setting up a Managed Agent from scratch. **Read `shared/managed-agents-onboarding.md` immediately** and follow its interview script: mental model → know-or-explore branch → template config → session setup → **pre-flight viability check** → emit code. The viability check (reconcile the stated job against configured tools/credentials/data) catches under-resourced setups — missing a tool, credential, or data access — before the agent burns budget. Do not summarize — run the interview. |

**Reading guide:** Start with `shared/managed-agents-overview.md`, then the topical `shared/managed-agents-*.md` files (core, environments, tools, events, outcomes, multiagent, webhooks, memory, scheduled-deployments, client-patterns, onboarding, api-reference). For Python, TypeScript, Go, Ruby, PHP, and Java, read `{lang}/managed-agents/README.md` for code examples. For cURL, read `curl/managed-agents.md`. **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `agents.create` and pass it to every subsequent `sessions.create`; do not call `agents.create` in the request path. The Anthropic CLI (`ant`) is one convenient way to create agents and environments from version-controlled YAML — see `shared/anthropic-cli.md`. If a binding you need isn't shown in the language README, WebFetch the relevant entry from `shared/live-sources.md` rather than guess. C# has beta Managed Agents support via `client.Beta.Agents` and related namespaces.

**When the user wants to set up a Managed Agent from scratch** (e.g. "how do I get started", "walk me through creating one", "set up a new agent"): read `shared/managed-agents-onboarding.md` and run its interview — same flow as the `managed-agents-onboard` subcommand.

**When the user asks "how do I write the client code for X":** reach for `shared/managed-agents-client-patterns.md` — covers lossless stream reconnect, `processed_at` queued/processed gate, interrupt, `tool_confirmation` round-trip, the correct idle/terminated break gate, post-idle status race, stream-first ordering, file-mount gotchas, keeping credentials host-side via custom tools, etc.

**When the user wants the agent to run on a schedule** (cron, "every night", "weekly report"): read `shared/managed-agents-scheduled-deployments.md` — deployments fire sessions autonomously on a cron cadence, with run records, retries, and auto-pause.


---

## Reading Guide

After detecting the language, read the relevant files based on what the user needs:

### Quick Task Reference

**Single text classification/summarization/extraction/Q&A:**
→ Read only `{lang}/claude-api/README.md`

**Chat UI or real-time response display:**
→ Read `{lang}/claude-api/README.md` + `{lang}/claude-api/streaming.md`

**Long-running conversations (may exceed context window):**
→ Read `{lang}/claude-api/README.md` — see Compaction section
**Migrating to a newer model (Fable 5 / Opus 4.8 / Opus 4.7 / Opus 4.6 / Sonnet 4.6) or replacing a retired model:**
→ Read `shared/model-migration.md`
**Prompting or tuning Fable 5 (long turns, effort, verbosity, autonomous runs, sub-agents):**
→ Read `shared/model-migration.md` → Migrating to Fable 5 → Behavioral shifts (prompt-tunable) + Long-running agent recommendations
**Prompt caching / optimize caching / "why is my cache hit rate low":**
→ Read `shared/prompt-caching.md` + `{lang}/claude-api/README.md` (Prompt Caching section)
**Count tokens in a file / prompt / diff ("how many tokens is X"):**
→ Read `shared/token-counting.md` — use `messages.count_tokens`, never `tiktoken`

**Function calling / tool use / agents:**
→ Read `{lang}/claude-api/README.md` + `shared/tool-use-concepts.md` + `{lang}/claude-api/tool-use.md`

**Agent design (tool surface, context management, caching strategy):**
→ Read `shared/agent-design.md`

**Batch processing (non-latency-sensitive):**
→ Read `{lang}/claude-api/README.md` + `{lang}/claude-api/batches.md`

**File uploads across multiple requests:**
→ Read `{lang}/claude-api/README.md` + `{lang}/claude-api/files-api.md`

**Managed Agents (server-managed stateful agents with workspace):**
→ Read `shared/managed-agents-overview.md` + the rest of the `shared/managed-agents-*.md` files. For Python, TypeScript, Go, Ruby, PHP, and Java, read `{lang}/managed-agents/README.md` for code examples. For cURL, read `curl/managed-agents.md`. **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `agents.create` and pass it to every subsequent `sessions.create`; do not call `agents.create` in the request path. The Anthropic CLI (`ant`) is one convenient way to create agents and environments from version-controlled YAML — see `shared/anthropic-cli.md`. If a binding you need isn't shown in the language README, WebFetch the relevant entry from `shared/live-sources.md` rather than guess. C# has beta Managed Agents support — see `csharp/claude-api.md` for details, or `curl/managed-agents.md` for raw HTTP reference.

### Claude API (Full File Reference)

Read the **language-specific Claude API folder** (`{language}/claude-api/`):

1. **`{language}/claude-api/README.md`** — **Read this first.** Installation, quick start, common patterns, error handling.
2. **`shared/tool-use-concepts.md`** — Read when the user needs function calling, code execution, memory, or structured outputs. Covers conceptual foundations.
3. **`shared/agent-design.md`** — Read when designing an agent: bash vs. dedicated tools, programmatic tool calling, tool search/skills, context editing vs. compaction vs. memory, caching principles.
4. **`{language}/claude-api/tool-use.md`** — Read for language-specific tool use code examples (tool runner, manual loop, code execution, memory, structured outputs).
5. **`{language}/claude-api/streaming.md`** — Read when building chat UIs or interfaces that display responses incrementally.
6. **`{language}/claude-api/batches.md`** — Read when processing many requests offline (not latency-sensitive). Runs asynchronously at 50% cost.
7. **`{language}/claude-api/files-api.md`** — Read when sending the same file across multiple requests without re-uploading.
8. **`shared/prompt-caching.md`** — Read when adding or optimizing prompt caching. Covers prefix-stability design, breakpoint placement, and anti-patterns that silently invalidate cache.
9. **`shared/error-codes.md`** — Read when debugging HTTP errors or implementing error handling.
10. **`shared/model-migration.md`** — Read when upgrading to newer models, replacing retired models, or translating `budget_tokens` / prefill patterns to the current API.
11. **`shared/live-sources.md`** — WebFetch URLs for fetching the latest official documentation.

> **Note:** For Java, Go, Ruby, C#, PHP, and cURL — these have a single file each covering all basics. Read that file plus `shared/tool-use-concepts.md` and `shared/error-codes.md` as needed.

> **Note:** For the Managed Agents file reference, see the `## Managed Agents (Beta)` section above — it lists every `shared/managed-agents-*.md` file and the language-specific READMEs.

---

## When to Use WebFetch

Use WebFetch to get the latest documentation when:

- User asks for "latest" or "current" information
- Cached data seems incorrect
- User asks about features not covered here

Live documentation URLs are in `shared/live-sources.md`.

## Common Pitfalls

- Don't truncate inputs when passing files or content to the API. If the content is too long to fit in the context window, notify the user and discuss options (chunking, summarization, etc.) rather than silently truncating.
- **Fable 5 / Opus 4.8 / 4.7 thinking:** Adaptive only. `thinking: {type: "enabled", budget_tokens: N}` returns 400 — `budget_tokens` is fully removed (along with `temperature`, `top_p`, `top_k`). Use `thinking: {type: "adaptive"}`. Opus 4.8 inherits this surface from 4.7 with no new breaking changes; Fable 5 adds one — an explicit `thinking: {type: "disabled"}` returns a 400 (accepted on 4.7/4.8); omit the param instead.
- **Opus 4.6 / Sonnet 4.6 thinking:** Use `thinking: {type: "adaptive"}` — do NOT use `budget_tokens` for new 4.6 code (deprecated on both Opus 4.6 and Sonnet 4.6; for gradual migration of existing code, see the transitional escape hatch in `shared/model-migration.md` — note this carve-out does not apply to Fable 5, Opus 4.7 or 4.8). For older models, `budget_tokens` must be less than `max_tokens` (minimum 1024). This will throw an error if you get it wrong.
- **Prefill removed (Fable 5 and the 4.6/4.7/4.8 family):** Assistant message prefills (last-assistant-turn prefills) return a 400 error on Fable 5, Opus 4.6, Opus 4.7, Opus 4.8, and Sonnet 4.6. Use structured outputs (`output_config.format`) or system prompt instructions to control response format instead. (One exception: the fallback-credit prefill claim — when redeeming a credit with `fallback_has_prefill_claim: true`, the server accepts the echoed assistant message; see the migration guide's refusal section.)
- **Fable 5 `refusal` stop reason:** Safety classifiers may decline a request — a successful HTTP 200 with `stop_reason: "refusal"` (pre-output: empty `content`, nothing billed; mid-stream: partial output billed — discard it). Check `stop_reason` before reading `response.content[0]`, or you'll hit index errors on refused requests. To retry on another model, replaying history as-is works — other models silently ignore the refused model's thinking blocks — but ignored blocks still bill input tokens, so strip them when switching for good (exception: a fallback-credit redemption must echo the refused body exactly, thinking blocks included).
- **Fable 5 tokenizer:** ~30% more tokens for the same content vs Opus-tier models. Token counts, context-window budgets, and `max_tokens` values measured on other models don't transfer — re-measure with `count_tokens` passing `model: "claude-fable-5"` (the response includes counts under both tokenizers).
- **Confirm migration scope before editing:** When a user asks to migrate code to a newer Claude model without naming a specific file, directory, or file list, **ask which scope to apply first** — the entire working directory, a specific subdirectory, or a specific set of files. Do not start editing until the user confirms. Imperative phrasings like "migrate my codebase", "move my project to X", "upgrade to Sonnet 4.6", or bare "migrate to Opus 4.8" are **still ambiguous** — they tell you what to do but not where, so ask. Proceed without asking only when the prompt names an exact file, a specific directory, or an explicit file list ("migrate `app.py`", "migrate everything under `services/`", "update `a.py` and `b.py`"). See `shared/model-migration.md` Step 0.
- **`max_tokens` defaults:** Don't lowball `max_tokens` — hitting the cap truncates output mid-thought and requires a retry. For non-streaming requests, default to `~16000` (keeps responses under SDK HTTP timeouts). For streaming requests, default to `~64000` (timeouts aren't a concern, so give the model room). Only go lower when you have a hard reason: classification (`~256`), cost caps, deliberately short outputs, or **`max_tokens: 0`** for cache pre-warming (see `shared/prompt-caching.md` → Pre-warming).
- **128K output tokens:** Fable 5, Opus 4.6, Opus 4.7, and Opus 4.8 support up to 128K `max_tokens`, but the SDKs require streaming for values that large to avoid HTTP timeouts. Use `.stream()` with `.get_final_message()` / `.finalMessage()`.
- **Tool call JSON parsing (Fable 5 and the 4.6/4.7/4.8 family):** Fable 5, Opus 4.6, Opus 4.7, Opus 4.8, and Sonnet 4.6 may produce different JSON string escaping in tool call `input` fields (e.g., Unicode or forward-slash escaping). Always parse tool inputs with `json.loads()` / `JSON.parse()` — never do raw string matching on the serialized input.
- **Structured outputs (all models):** Use `output_config: {format: {...}}` instead of the deprecated `output_format` parameter on `messages.create()`. This is a general API change, not 4.6-specific.
- **Don't reimplement SDK functionality:** The SDK provides high-level helpers — use them instead of building from scratch. Specifically: use `stream.finalMessage()` instead of wrapping `.on()` events in `new Promise()`; use typed exception classes (`Anthropic.RateLimitError`, etc.) instead of string-matching error messages; use SDK types (`Anthropic.MessageParam`, `Anthropic.Tool`, `Anthropic.Message`, etc.) instead of redefining equivalent interfaces.
- **Don't define custom types for SDK data structures:** The SDK exports types for all API objects. Use `Anthropic.MessageParam` for messages, `Anthropic.Tool` for tool definitions, `Anthropic.ToolUseBlock` / `Anthropic.ToolResultBlockParam` for tool results, `Anthropic.Message` for responses. Defining your own `interface ChatMessage { role: string; content: unknown }` duplicates what the SDK already provides and loses type safety.
- **Report and document output:** For tasks that produce reports, documents, or visualizations, the code execution sandbox has `python-docx`, `python-pptx`, `matplotlib`, `pillow`, and `pypdf` pre-installed. Claude can generate formatted files (DOCX, PDF, charts) and return them via the Files API — consider this for "report" or "document" type requests instead of plain stdout text.

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:csharp/claude-api.md
# Claude API — C#

> **Note:** The C# SDK is the official Anthropic SDK for C#. Tool use is supported via the Messages API with a beta `BetaToolRunner` for automatic tool execution loops. The SDK also supports Microsoft.Extensions.AI IChatClient integration with function invocation and Managed Agents (beta).

## Installation

```bash
dotnet add package Anthropic
```

## Client Initialization

```csharp
using Anthropic;

// Default (uses ANTHROPIC_API_KEY env var)
AnthropicClient client = new();

// Explicit API key (use environment variables — never hardcode keys)
AnthropicClient client = new() {
    ApiKey = Environment.GetEnvironmentVariable("ANTHROPIC_API_KEY")
};
```

---

## Basic Message Request

```csharp
using Anthropic.Models.Messages;

var parameters = new MessageCreateParams
{
    Model = Model.ClaudeOpus4_6,
    MaxTokens = 16000,
    Messages = [new() { Role = Role.User, Content = "What is the capital of France?" }]
};
var response = await client.Messages.Create(parameters);

// ContentBlock is a union wrapper. .Value unwraps to the variant object,
// then OfType<T> filters to the type you want. Or use the TryPick* idiom
// shown in the Thinking section below.
foreach (var text in response.Content.Select(b => b.Value).OfType<TextBlock>())
{
    Console.WriteLine(text.Text);
}
```

---

## Streaming

```csharp
using Anthropic.Models.Messages;

var parameters = new MessageCreateParams
{
    Model = Model.ClaudeOpus4_6,
    MaxTokens = 64000,
    Messages = [new() { Role = Role.User, Content = "Write a haiku" }]
};

await foreach (RawMessageStreamEvent streamEvent in client.Messages.CreateStreaming(parameters))
{
    if (streamEvent.TryPickContentBlockDelta(out var delta) &&
        delta.Delta.TryPickText(out var text))
    {
        Console.Write(text.Text);
    }
}
```

**`RawMessageStreamEvent` TryPick methods** (naming drops the `Message`/`Raw` prefix): `TryPickStart`, `TryPickDelta`, `TryPickStop`, `TryPickContentBlockStart`, `TryPickContentBlockDelta`, `TryPickContentBlockStop`. There is no `TryPickMessageStop` — use `TryPickStop`.

---

## Thinking

**Adaptive thinking is the recommended mode for Claude 4.6+ models.** Claude decides dynamically when and how much to think.

```csharp
using Anthropic.Models.Messages;

var response = await client.Messages.Create(new MessageCreateParams
{
    Model = Model.ClaudeOpus4_6,
    MaxTokens = 16000,
    // ThinkingConfigParam? implicitly converts from the concrete variant classes —
    // no wrapper needed.
    Thinking = new ThinkingConfigAdaptive(),
    Messages =
    [
        new() { Role = Role.User, Content = "Solve: 27 * 453" },
    ],
});

// ThinkingBlock(s) precede TextBlock in Content. TryPick* narrows the union.
foreach (var block in response.Content)
{
    if (block.TryPickThinking(out ThinkingBlock? t))
    {
        Console.WriteLine($"[thinking] {t.Thinking}");
    }
    else if (block.TryPickText(out TextBlock? text))
    {
        Console.WriteLine(text.Text);
    }
}
```

> **Deprecated:** `new ThinkingConfigEnabled { BudgetTokens = N }` (fixed-budget extended thinking) still works on Claude 4.6 but is deprecated. Use adaptive thinking above.

Alternative to `TryPick*`: `.Select(b => b.Value).OfType<ThinkingBlock>()` (same LINQ pattern as the Basic Message example).

---

## Tool Use

### Defining a tool

`Tool` (NOT `ToolParam`) with an `InputSchema` record. `InputSchema.Type` is auto-set to `"object"` by the constructor — don't set it. `ToolUnion` has an implicit conversion from `Tool`, triggered by the collection expression `[...]`.

```csharp
using System.Text.Json;
using Anthropic.Models.Messages;

var parameters = new MessageCreateParams
{
    Model = Model.ClaudeSonnet4_6,
    MaxTokens = 16000,
    Tools = [
        new Tool {
            Name = "get_weather",
            Description = "Get the current weather in a given location",
            InputSchema = new() {
                Properties = new Dictionary<string, JsonElement> {
                    ["location"] = JsonSerializer.SerializeToElement(
                        new { type = "string", description = "City name" }),
                },
                Required = ["location"],
            },
        },
    ],
    Messages = [new() { Role = Role.User, Content = "Weather in Paris?" }],
};
```

Derived from `anthropic-sdk-csharp/src/Anthropic/Models/Messages/Tool.cs` and `ToolUnion.cs:799` (implicit conversion).

See [shared tool use concepts](../shared/tool-use-concepts.md) for the loop pattern.
### Converting response content to the follow-up assistant message

When echoing Claude's response back in the assistant turn, **there is no `.ToParam()` helper** — manually reconstruct each `ContentBlock` variant as its `*Param` counterpart. Do NOT use `new ContentBlockParam(block.Json)`: it compiles and serializes, but `.Value` stays `null` so `TryPick*`/`Validate()` fail (degraded JSON pass-through, not the typed path).

```csharp
using Anthropic.Models.Messages;

Message response = await client.Messages.Create(parameters);

// No .ToParam() — reconstruct per variant. Implicit conversions from each
// *Param type to ContentBlockParam mean no explicit wrapper.
List<ContentBlockParam> assistantContent = [];
List<ContentBlockParam> toolResults = [];
foreach (ContentBlock block in response.Content)
{
    if (block.TryPickText(out TextBlock? text))
    {
        assistantContent.Add(new TextBlockParam { Text = text.Text });
    }
    else if (block.TryPickThinking(out ThinkingBlock? thinking))
    {
        // Signature MUST be preserved — the API rejects tampering
        assistantContent.Add(new ThinkingBlockParam
        {
            Thinking = thinking.Thinking,
            Signature = thinking.Signature,
        });
    }
    else if (block.TryPickRedactedThinking(out RedactedThinkingBlock? redacted))
    {
        assistantContent.Add(new RedactedThinkingBlockParam { Data = redacted.Data });
    }
    else if (block.TryPickToolUse(out ToolUseBlock? toolUse))
    {
        // ToolUseBlock has required Caller; ToolUseBlockParam.Caller is optional — don't copy it
        assistantContent.Add(new ToolUseBlockParam
        {
            ID = toolUse.ID,
            Name = toolUse.Name,
            Input = toolUse.Input,
        });
        // Execute the tool; collect ONE result per tool_use block — the API
        // rejects the follow-up if any tool_use ID lacks a matching tool_result.
        string result = ExecuteYourTool(toolUse.Name, toolUse.Input);
        toolResults.Add(new ToolResultBlockParam
        {
            ToolUseID = toolUse.ID,
            Content = result,
        });
    }
}

// Follow-up: prior messages + assistant echo + user tool_result(s)
List<MessageParam> followUpMessages =
[
    .. parameters.Messages,
    new() { Role = Role.Assistant, Content = assistantContent },
    new() { Role = Role.User, Content = toolResults },
];
```

`ToolResultBlockParam` has no tuple constructor — use the object initializer. `Content` is a string-or-list union; a plain `string` implicitly converts.

---

## Context Editing / Compaction (Beta)

**Beta-namespace prefix is inconsistent** (source-verified against `src/Anthropic/Models/Beta/Messages/*.cs` @ 12.9.0). No prefix: `MessageCreateParams`, `MessageCountTokensParams`, `Role`. **Everything else has the `Beta` prefix**: `BetaMessageParam`, `BetaMessage`, `BetaContentBlock`, `BetaToolUseBlock`, all block param types. The unprefixed `Role` WILL collide with `Anthropic.Models.Messages.Role` if you import both namespaces (CS0104). Safest: import only Beta; if mixing, alias the beta `Role`:

```csharp
using Anthropic.Models.Beta.Messages;
using NonBeta = Anthropic.Models.Messages;  // only if you also need non-beta types
// Now: MessageCreateParams, BetaMessageParam, Role (beta's), NonBeta.Role (if needed)
```


`BetaMessage.Content` is `IReadOnlyList<BetaContentBlock>` — a 15-variant discriminated union. Narrow with `TryPick*`. **Response `BetaContentBlock` is NOT assignable to param `BetaContentBlockParam`** — there's no `.ToParam()` in C#. Round-trip by converting each block:

```csharp
using Anthropic.Models.Beta.Messages;

var betaParams = new MessageCreateParams   // no Beta prefix — one of only 2 unprefixed
{
    Model = Model.ClaudeOpus4_6,
    MaxTokens = 16000,
    Betas = ["compact-2026-01-12"],
    ContextManagement = new BetaContextManagementConfig
    {
        Edits = [new BetaCompact20260112Edit()],
    },
    Messages = messages,
};
BetaMessage resp = await client.Beta.Messages.Create(betaParams);

foreach (BetaContentBlock block in resp.Content)
{
    if (block.TryPickCompaction(out BetaCompactionBlock? compaction))
    {
        // Content is nullable — compaction can fail server-side
        Console.WriteLine($"compaction summary: {compaction.Content}");
    }
}

// Context-edit metadata lives on a separate nullable field
if (resp.ContextManagement is { } ctx)
{
    foreach (var edit in ctx.AppliedEdits)
        Console.WriteLine($"cleared {edit.ClearedInputTokens} tokens");
}

// ROUND-TRIP: BetaMessageParam.Content is BetaMessageParamContent (a string|list
// union). It implicit-converts from List<BetaContentBlockParam>, NOT from the
// response's IReadOnlyList<BetaContentBlock>. Convert each block:
List<BetaContentBlockParam> paramBlocks = [];
foreach (var b in resp.Content)
{
    if (b.TryPickText(out var t)) paramBlocks.Add(new BetaTextBlockParam { Text = t.Text });
    else if (b.TryPickCompaction(out var c)) paramBlocks.Add(new BetaCompactionBlockParam { Content = c.Content });
    // ... other variants as needed
}
messages.Add(new BetaMessageParam { Role = Role.Assistant, Content = paramBlocks });
```

All 15 `BetaContentBlock.TryPick*` variants: `Text`, `Thinking`, `RedactedThinking`, `ToolUse`, `ServerToolUse`, `WebSearchToolResult`, `WebFetchToolResult`, `CodeExecutionToolResult`, `BashCodeExecutionToolResult`, `TextEditorCodeExecutionToolResult`, `ToolSearchToolResult`, `McpToolUse`, `McpToolResult`, `ContainerUpload`, `Compaction`.

**`BetaToolUseBlock.Input` is `IReadOnlyDictionary<string, JsonElement>`** — index by key then call the `JsonElement` extractor:

```csharp
if (block.TryPickToolUse(out BetaToolUseBlock? tu))
{
    int a = tu.Input["a"].GetInt32();
    string s = tu.Input["name"].GetString()!;
}
```

---

## Effort Parameter

Effort is nested under `OutputConfig`, NOT a top-level property. `ApiEnum<string, Effort>` has an implicit conversion from the enum, so assign `Effort.High` directly.

```csharp
OutputConfig = new OutputConfig { Effort = Effort.High },
```

Values: `Effort.Low`, `Effort.Medium`, `Effort.High`, `Effort.Max`. Combine with `Thinking = new ThinkingConfigAdaptive()` for cost-quality control.

---

## Prompt Caching

`System` takes `MessageCreateParamsSystem?` — a union of `string` or `List<TextBlockParam>`. There is no `SystemTextBlockParam`; use plain `TextBlockParam`. The implicit conversion needs the concrete `List<TextBlockParam>` type (array literals won't convert). For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.

```csharp
System = new List<TextBlockParam> {
    new() {
        Text = longSystemPrompt,
        CacheControl = new CacheControlEphemeral(),  // auto-sets Type = "ephemeral"
    },
},
```

Optional `Ttl` on `CacheControlEphemeral`: `new() { Ttl = Ttl.Ttl1h }` or `Ttl.Ttl5m`. `CacheControl` also exists on `Tool.CacheControl` and top-level `MessageCreateParams.CacheControl`.

Verify hits via `response.Usage.CacheCreationInputTokens` / `response.Usage.CacheReadInputTokens`.

---

## Token Counting

```csharp
MessageTokensCount result = await client.Messages.CountTokens(new MessageCountTokensParams {
    Model = Model.ClaudeOpus4_6,
    Messages = [new() { Role = Role.User, Content = "Hello" }],
});
long tokens = result.InputTokens;
```

`MessageCountTokensParams.Tools` uses a different union type (`MessageCountTokensTool`) than `MessageCreateParams.Tools` (`ToolUnion`) — if you're passing tools, the compiler will tell you when it matters.

---

## Structured Output

```csharp
OutputConfig = new OutputConfig {
    Format = new JsonOutputFormat {
        Schema = new Dictionary<string, JsonElement> {
            ["type"] = JsonSerializer.SerializeToElement("object"),
            ["properties"] = JsonSerializer.SerializeToElement(
                new { name = new { type = "string" } }),
            ["required"] = JsonSerializer.SerializeToElement(new[] { "name" }),
        },
    },
},
```

`JsonOutputFormat.Type` is auto-set to `"json_schema"` by the constructor. `Schema` is `required`.

---

## PDF / Document Input

`DocumentBlockParam` takes a `DocumentBlockParamSource` union: `Base64PdfSource` / `UrlPdfSource` / `PlainTextSource` / `ContentBlockSource`. `Base64PdfSource` auto-sets `MediaType = "application/pdf"` and `Type = "base64"`.

```csharp
new MessageParam {
    Role = Role.User,
    Content = new List<ContentBlockParam> {
        new DocumentBlockParam { Source = new Base64PdfSource { Data = base64String } },
        new TextBlockParam { Text = "Summarize this PDF" },
    },
}
```

---

## Server-Side Tools

Web search, bash, text editor, and code execution are built-in server tools. Type names are version-suffixed; constructors auto-set `name`/`type`. All implicit-convert to `ToolUnion`.

```csharp
Tools = [
    new WebSearchTool20260209(),
    new ToolBash20250124(),
    new ToolTextEditor20250728(),
    new CodeExecutionTool20260120(),
],
```

Also available: `WebFetchTool20260209`, `MemoryTool20250818`. `WebSearchTool20260209` optionals: `AllowedDomains`, `BlockedDomains`, `MaxUses`, `UserLocation`.

---

## Files API (Beta)

Files live under `client.Beta.Files` (namespace `Anthropic.Models.Beta.Files`). `BinaryContent` implicit-converts from `Stream` and `byte[]`.

```csharp
using Anthropic.Models.Beta.Files;
using Anthropic.Models.Beta.Messages;

FileMetadata meta = await client.Beta.Files.Upload(
    new FileUploadParams { File = File.OpenRead("doc.pdf") });

// Referencing the uploaded file requires Beta message types:
new BetaRequestDocumentBlock {
    Source = new BetaFileDocumentSource { FileID = meta.ID },
}
```

The non-beta `DocumentBlockParamSource` union has no file-ID variant — file references need `client.Beta.Messages.Create()`.

---

## Tool Runner (Beta)

The C# SDK provides a `BetaToolRunner` for automatic tool execution loops. Define tools with raw JSON schemas, and the runner handles the API call → tool execution → result feedback loop.

```csharp
using Anthropic.Models.Beta.Messages;

// Define tools and create params as shown in the Tool Use section above,
// but using the beta namespace types (BetaToolUnion, etc.)
var runner = client.Beta.Messages.ToolRunner(betaParams);

await foreach (BetaMessage message in runner)
{
    foreach (var block in message.Content)
    {
        if (block.TryPickText(out var text))
        {
            Console.WriteLine(text.Text);
        }
    }
}
```

---

## Stop Details

When `StopReason` is `"refusal"`, the response includes structured `StopDetails`:

```csharp
if (response.StopReason == "refusal" && response.StopDetails is { } details)
{
    Console.WriteLine($"Category: {details.Category}");
    Console.WriteLine($"Explanation: {details.Explanation}");
}
```

---

## Managed Agents (Beta)

The C# SDK supports Managed Agents via `client.Beta.Agents`, `client.Beta.Sessions`, `client.Beta.Environments`, and related namespaces. See `shared/managed-agents-overview.md` for the architecture and `curl/managed-agents.md` for the wire-level reference.

FILE:curl/examples.md
# Claude API — cURL / Raw HTTP

Use these examples when the user needs raw HTTP requests or is working in a language without an official SDK.

## Setup

```bash
export ANTHROPIC_API_KEY="your-api-key"
```

---

## Basic Message Request

```bash
curl https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 16000,
    "messages": [
      {"role": "user", "content": "What is the capital of France?"}
    ]
  }'
```

### Parsing the response

Use `jq` to extract fields from the JSON response. Do not use `grep`/`sed` —
JSON strings can contain any character and regex parsing will break on quotes,
escapes, or multi-line content.

```bash
# Capture the response, then extract fields
response=$(curl -s https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{"model":"claude-opus-4-8","max_tokens":16000,"messages":[{"role":"user","content":"Hello"}]}')

# Print the first text block (-r strips the JSON quotes)
echo "$response" | jq -r '.content[0].text'

# Read usage fields
input_tokens=$(echo "$response" | jq -r '.usage.input_tokens')
output_tokens=$(echo "$response" | jq -r '.usage.output_tokens')

# Read stop reason (for tool-use loops)
stop_reason=$(echo "$response" | jq -r '.stop_reason')

# Extract all text blocks (content is an array; filter to type=="text")
echo "$response" | jq -r '.content[] | select(.type == "text") | .text'
```


---

## Streaming (SSE)

```bash
curl https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 64000,
    "stream": true,
    "messages": [{"role": "user", "content": "Write a haiku"}]
  }'
```

The response is a stream of Server-Sent Events:

```
event: message_start
data: {"type":"message_start","message":{"id":"msg_...","type":"message",...}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Hello"}}

event: content_block_stop
data: {"type":"content_block_stop","index":0}

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn"},"usage":{"output_tokens":12}}

event: message_stop
data: {"type":"message_stop"}
```

---

## Tool Use

```bash
curl https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 16000,
    "tools": [{
      "name": "get_weather",
      "description": "Get current weather for a location",
      "input_schema": {
        "type": "object",
        "properties": {
          "location": {"type": "string", "description": "City name"}
        },
        "required": ["location"]
      }
    }],
    "messages": [{"role": "user", "content": "What is the weather in Paris?"}]
  }'
```

When Claude responds with a `tool_use` block, send the result back:

```bash
curl https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 16000,
    "tools": [{
      "name": "get_weather",
      "description": "Get current weather for a location",
      "input_schema": {
        "type": "object",
        "properties": {
          "location": {"type": "string", "description": "City name"}
        },
        "required": ["location"]
      }
    }],
    "messages": [
      {"role": "user", "content": "What is the weather in Paris?"},
      {"role": "assistant", "content": [
        {"type": "text", "text": "Let me check the weather."},
        {"type": "tool_use", "id": "toolu_abc123", "name": "get_weather", "input": {"location": "Paris"}}
      ]},
      {"role": "user", "content": [
        {"type": "tool_result", "tool_use_id": "toolu_abc123", "content": "72°F and sunny"}
      ]}
    ]
  }'
```

---

## Prompt Caching

Put `cache_control` on the last block of the stable prefix. See `shared/prompt-caching.md` for placement patterns and the silent-invalidator audit checklist.

```bash
curl https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 16000,
    "system": [
      {"type": "text", "text": "<large shared prompt...>", "cache_control": {"type": "ephemeral"}}
    ],
    "messages": [{"role": "user", "content": "Summarize the key points"}]
  }'
```

For 1-hour TTL: `"cache_control": {"type": "ephemeral", "ttl": "1h"}`. Top-level `"cache_control"` on the request body auto-places on the last cacheable block. Verify hits via the response `usage.cache_creation_input_tokens` / `usage.cache_read_input_tokens` fields.

---

## Extended Thinking

> **Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6:** Use adaptive thinking. `budget_tokens` is removed on Fable 5, Opus 4.8, and 4.7 (400 if sent); deprecated on Opus 4.6 and Sonnet 4.6.
> **Older models:** Use `"type": "enabled"` with `"budget_tokens": N` (must be < `max_tokens`, min 1024).

```bash
# Fable 5 / Opus 4.8 / 4.7 / 4.6: adaptive thinking (recommended)
curl https://api.anthropic.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 16000,
    "thinking": {
      "type": "adaptive"
    },
    "output_config": {
      "effort": "high"
    },
    "messages": [{"role": "user", "content": "Solve this step by step..."}]
  }'
```

---

## Required Headers

| Header              | Value              | Description                |
| ------------------- | ------------------ | -------------------------- |
| `Content-Type`      | `application/json` | Required                   |
| `x-api-key`         | Your API key       | Authentication             |
| `anthropic-version` | `2023-06-01`       | API version                |
| `anthropic-beta`    | Beta feature IDs   | Required for beta features |

FILE:curl/managed-agents.md
# Managed Agents — cURL / Raw HTTP

Use these examples when the user needs raw HTTP requests or is working without an SDK.

## Setup

```bash
export ANTHROPIC_API_KEY="your-api-key"

# Common headers
HEADERS=(
  -H "Content-Type: application/json"
  -H "x-api-key: $ANTHROPIC_API_KEY"
  -H "anthropic-version: 2023-06-01"
  -H "anthropic-beta: managed-agents-2026-04-01"
)
```

---

## Create an Environment

```bash
curl -X POST https://api.anthropic.com/v1/environments \
  "HEADERS[@]" \
  -d '{
    "name": "my-dev-env",
    "config": {
      "type": "cloud",
      "networking": { "type": "unrestricted" }
    }
  }'
```

### With restricted networking

```bash
curl -X POST https://api.anthropic.com/v1/environments \
  "HEADERS[@]" \
  -d '{
    "name": "restricted-env",
    "config": {
      "type": "cloud",
      "networking": {
        "type": "limited",
        "allow_package_managers": true,
        "allow_mcp_servers": true,
        "allowed_hosts": ["api.example.com"]
      }
    }
  }'
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** Under `managed-agents-2026-04-01`, `model`/`system`/`tools` are top-level fields on `POST /v1/agents`, not on the session. Always create the agent first — the session only takes `"agent": {"type": "agent", "id": "..."}`.

### Minimal

```bash
# 1. Create the agent
curl -X POST https://api.anthropic.com/v1/agents \
  "HEADERS[@]" \
  -d '{
    "name": "Coding Assistant",
    "model": "claude-opus-4-8",
    "tools": [{ "type": "agent_toolset_20260401" }]
  }'
# → { "id": "agent_abc123", ... }

# 2. Start a session
curl -X POST https://api.anthropic.com/v1/sessions \
  "HEADERS[@]" \
  -d '{
    "agent": { "type": "agent", "id": "agent_abc123", "version": "1772585501101368014" },
    "environment_id": "env_abc123"
  }'
```

### With system prompt, custom tools, and GitHub repo

```bash
# 1. Create the agent
curl -X POST https://api.anthropic.com/v1/agents \
  "HEADERS[@]" \
  -d '{
    "name": "Code Reviewer",
    "model": "claude-opus-4-8",
    "system": "You are a senior code reviewer. Be thorough and constructive.",
    "tools": [
      { "type": "agent_toolset_20260401" },
      {
        "type": "custom",
        "name": "run_linter",
        "description": "Run the project linter on a file",
        "input_schema": {
          "type": "object",
          "properties": {
            "file_path": { "type": "string", "description": "Path to lint" }
          },
          "required": ["file_path"]
        }
      }
    ]
  }'

# 2. Start a session with the repo mounted
curl -X POST https://api.anthropic.com/v1/sessions \
  "HEADERS[@]" \
  -d '{
    "agent": { "type": "agent", "id": "agent_abc123", "version": "1772585501101368014" },
    "environment_id": "env_abc123",
    "title": "Code review session",
    "resources": [
      {
        "type": "github_repository",
        "url": "https://github.com/owner/repo",
        "mount_path": "/workspace/repo",
        "authorization_token": "ghp_...",
        "branch": "feature-branch"
      }
    ]
  }'
```

---

## Send a User Message

```bash
curl -X POST https://api.anthropic.com/v1/sessions/$SESSION_ID/events \
  "HEADERS[@]" \
  -d '{
    "events": [
      {
        "type": "user.message",
        "content": [{ "type": "text", "text": "Review the auth module for security issues" }]
      }
    ]
  }'
```

---

## Stream Events (SSE)

```bash
curl -N https://api.anthropic.com/v1/sessions/$SESSION_ID/events/stream \
  "HEADERS[@]"
```

Response format:

```
event: session.status_running
data: {"type":"session.status_running","id":"sevt_...","processed_at":"..."}

event: agent.message
data: {"type":"agent.message","id":"sevt_...","content":[{"type":"text","text":"I'll review..."}],"processed_at":"..."}

event: session.status_idle
data: {"type":"session.status_idle","id":"sevt_...","processed_at":"..."}
```

---

## Poll Events

```bash
# Get all events
curl https://api.anthropic.com/v1/sessions/$SESSION_ID/events \
  "HEADERS[@]"

# Paginated — get next page of events
curl "https://api.anthropic.com/v1/sessions/$SESSION_ID/events?page=page_abc123" \
  "HEADERS[@]"
```

---

## Provide Custom Tool Result

When the agent calls a custom tool, send the result back:

```bash
curl -X POST https://api.anthropic.com/v1/sessions/$SESSION_ID/events \
  "HEADERS[@]" \
  -d '{
    "events": [
      {
        "type": "user.custom_tool_result",
        "custom_tool_use_id": "sevt_abc123",
        "content": [{ "type": "text", "text": "No linting errors found." }]
      }
    ]
  }'
```

---

## Interrupt a Running Session

```bash
curl -X POST https://api.anthropic.com/v1/sessions/$SESSION_ID/events \
  "HEADERS[@]" \
  -d '{
    "events": [
      {
        "type": "interrupt"
      }
    ]
  }'
```

---

## Get Session Details

```bash
curl https://api.anthropic.com/v1/sessions/$SESSION_ID \
  "HEADERS[@]"
```

---

## List Sessions

```bash
curl https://api.anthropic.com/v1/sessions \
  "HEADERS[@]"
```

---

## Delete a Session

```bash
curl -X DELETE https://api.anthropic.com/v1/sessions/$SESSION_ID \
  "HEADERS[@]"
```

---

## Upload a File

```bash
curl -X POST https://api.anthropic.com/v1/files \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14" \
  -F "file=@path/to/file.txt"
```

---

## List and Download Session Files

List files the agent wrote to `/mnt/session/outputs/` during a session, then download them.

```bash
# List files associated with a session
curl "https://api.anthropic.com/v1/files?scope_id=$SESSION_ID" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14,managed-agents-2026-04-01"

# Download a specific file
curl "https://api.anthropic.com/v1/files/$FILE_ID/content" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14,managed-agents-2026-04-01" \
  -o downloaded_file.txt
```

---

## List Agents

```bash
curl https://api.anthropic.com/v1/agents \
  "HEADERS[@]"
```

---

## MCP Server Integration

```bash
# 1. Agent declares MCP server (no auth here — auth goes in a vault)
curl -X POST https://api.anthropic.com/v1/agents \
  "HEADERS[@]" \
  -d '{
    "name": "MCP Agent",
    "model": "claude-opus-4-8",
    "mcp_servers": [
      { "type": "url", "name": "my-tools", "url": "https://my-mcp-server.example.com/sse" }
    ],
    "tools": [
      { "type": "agent_toolset_20260401" },
      { "type": "mcp_toolset", "mcp_server_name": "my-tools" }
    ]
  }'

# 2. Session attaches vault containing credentials for that MCP server URL
curl -X POST https://api.anthropic.com/v1/sessions \
  "HEADERS[@]" \
  -d '{
    "agent": "agent_abc123",
    "environment_id": "env_abc123",
    "vault_ids": ["vlt_abc123"]
  }'
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

---

## Tool Configuration

```bash
curl -X POST https://api.anthropic.com/v1/agents \
  "HEADERS[@]" \
  -d '{
    "name": "Restricted Agent",
    "model": "claude-opus-4-8",
    "tools": [
      {
        "type": "agent_toolset_20260401",
        "default_config": { "enabled": true },
        "configs": [
          { "name": "bash", "enabled": false }
        ]
      }
    ]
  }'
```

FILE:go/claude-api.md
# Claude API — Go

> **Note:** The Go SDK supports the Claude API and beta tool use with `BetaToolRunner`. Agent SDK is not yet available for Go.

## Installation

```bash
go get github.com/anthropics/anthropic-sdk-go
```

## Client Initialization

```go
import (
    "github.com/anthropics/anthropic-sdk-go"
    "github.com/anthropics/anthropic-sdk-go/option"
)

// Default (uses ANTHROPIC_API_KEY env var)
client := anthropic.NewClient()

// Explicit API key
client := anthropic.NewClient(
    option.WithAPIKey("your-api-key"),
)
```

---

## Model Constants

The Go SDK provides typed model constants: `anthropic.ModelClaudeFable5`, `anthropic.ModelClaudeOpus4_8`, `anthropic.ModelClaudeOpus4_7`, `anthropic.ModelClaudeSonnet4_6`, `anthropic.ModelClaudeHaiku4_5_20251001`. Use `ModelClaudeOpus4_8` unless the user specifies otherwise; if they ask for Fable or the most powerful model, use `anthropic.ModelClaudeFable5` (see `shared/models.md` for the full resolution table).

---

## Basic Message Request

```go
response, err := client.Messages.New(context.Background(), anthropic.MessageNewParams{
    Model:     anthropic.ModelClaudeOpus4_8,
    MaxTokens: 16000,
    Messages: []anthropic.MessageParam{
        anthropic.NewUserMessage(anthropic.NewTextBlock("What is the capital of France?")),
    },
})
if err != nil {
    log.Fatal(err)
}
for _, block := range response.Content {
    switch variant := block.AsAny().(type) {
    case anthropic.TextBlock:
        fmt.Println(variant.Text)
    }
}
```

---

## Streaming

```go
stream := client.Messages.NewStreaming(context.Background(), anthropic.MessageNewParams{
    Model:     anthropic.ModelClaudeOpus4_6,
    MaxTokens: 64000,
    Messages: []anthropic.MessageParam{
        anthropic.NewUserMessage(anthropic.NewTextBlock("Write a haiku")),
    },
})

for stream.Next() {
    event := stream.Current()
    switch eventVariant := event.AsAny().(type) {
    case anthropic.ContentBlockDeltaEvent:
        switch deltaVariant := eventVariant.Delta.AsAny().(type) {
        case anthropic.TextDelta:
            fmt.Print(deltaVariant.Text)
        }
    }
}
if err := stream.Err(); err != nil {
    log.Fatal(err)
}
```

**Accumulating the final message** (there is no `GetFinalMessage()` on the stream):

```go
stream := client.Messages.NewStreaming(ctx, params)
message := anthropic.Message{}
for stream.Next() {
    message.Accumulate(stream.Current())
}
if err := stream.Err(); err != nil { log.Fatal(err) }
// message.Content now has the complete response
```


---

## Tool Use

### Tool Runner (Beta — Recommended)

**Beta:** The Go SDK provides `BetaToolRunner` for automatic tool use loops via the `toolrunner` package.

```go
import (
    "context"
    "fmt"
    "log"

    "github.com/anthropics/anthropic-sdk-go"
    "github.com/anthropics/anthropic-sdk-go/toolrunner"
)

// Define tool input with jsonschema tags for automatic schema generation
type GetWeatherInput struct {
    City string `json:"city" jsonschema:"required,description=The city name"`
}

// Create a tool with automatic schema generation from struct tags
weatherTool, err := toolrunner.NewBetaToolFromJSONSchema(
    "get_weather",
    "Get current weather for a city",
    func(ctx context.Context, input GetWeatherInput) (anthropic.BetaToolResultBlockParamContentUnion, error) {
        return anthropic.BetaToolResultBlockParamContentUnion{
            OfText: &anthropic.BetaTextBlockParam{
                Text: fmt.Sprintf("The weather in %s is sunny, 72°F", input.City),
            },
        }, nil
    },
)
if err != nil {
    log.Fatal(err)
}

// Create a tool runner that handles the conversation loop automatically
runner := client.Beta.Messages.NewToolRunner(
    []anthropic.BetaTool{weatherTool},
    anthropic.BetaToolRunnerParams{
        BetaMessageNewParams: anthropic.BetaMessageNewParams{
            Model:     anthropic.ModelClaudeOpus4_6,
            MaxTokens: 16000,
            Messages: []anthropic.BetaMessageParam{
                anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock("What's the weather in Paris?")),
            },
        },
        MaxIterations: 5,
    },
)

// Run until Claude produces a final response
message, err := runner.RunToCompletion(context.Background())
if err != nil {
    log.Fatal(err)
}

// RunToCompletion returns *BetaMessage; content is []BetaContentBlockUnion.
// Narrow via AsAny() switch — note the Beta-namespace types (BetaTextBlock,
// not TextBlock):
for _, block := range message.Content {
    switch block := block.AsAny().(type) {
    case anthropic.BetaTextBlock:
        fmt.Println(block.Text)
    }
}
```

**Key features of the Go tool runner:**

- Automatic schema generation from Go structs via `jsonschema` tags
- `RunToCompletion()` for simple one-shot usage
- `All()` iterator for processing each message in the conversation
- `NextMessage()` for step-by-step iteration
- Streaming variant via `NewToolRunnerStreaming()` with `AllStreaming()`

### Manual Loop

For fine-grained control over the agentic loop, define tools with `ToolParam`, check `StopReason`, execute tools yourself, and feed `tool_result` blocks back. This is the pattern when you need to intercept, validate, or log tool calls.

Derived from `anthropic-sdk-go/examples/tools/main.go`.

```go
package main

import (
    "context"
    "encoding/json"
    "fmt"
    "log"

    "github.com/anthropics/anthropic-sdk-go"
)

func main() {
    client := anthropic.NewClient()

    // 1. Define tools. ToolParam.InputSchema uses a map, no struct tags needed.
    addTool := anthropic.ToolParam{
        Name:        "add",
        Description: anthropic.String("Add two integers"),
        InputSchema: anthropic.ToolInputSchemaParam{
            Properties: map[string]any{
                "a": map[string]any{"type": "integer"},
                "b": map[string]any{"type": "integer"},
            },
        },
    }
    // ToolParam must be wrapped in ToolUnionParam for the Tools slice
    tools := []anthropic.ToolUnionParam{{OfTool: &addTool}}

    messages := []anthropic.MessageParam{
        anthropic.NewUserMessage(anthropic.NewTextBlock("What is 2 + 3?")),
    }

    for {
        resp, err := client.Messages.New(context.Background(), anthropic.MessageNewParams{
            Model:     anthropic.ModelClaudeSonnet4_6,
            MaxTokens: 16000,
            Messages:  messages,
            Tools:     tools,
        })
        if err != nil {
            log.Fatal(err)
        }

        // 2. Append the assistant response to history BEFORE processing tool calls.
        //    resp.ToParam() converts Message → MessageParam in one call.
        messages = append(messages, resp.ToParam())

        // 3. Walk content blocks. ContentBlockUnion is a flattened struct;
        //    use block.AsAny().(type) to switch on the actual variant.
        toolResults := []anthropic.ContentBlockParamUnion{}
        for _, block := range resp.Content {
            switch variant := block.AsAny().(type) {
            case anthropic.TextBlock:
                fmt.Println(variant.Text)
            case anthropic.ToolUseBlock:
                // 4. Parse the tool input. Use variant.JSON.Input.Raw() to get the
                //    raw JSON — block.Input is json.RawMessage, not the parsed value.
                var in struct {
                    A int `json:"a"`
                    B int `json:"b"`
                }
                if err := json.Unmarshal([]byte(variant.JSON.Input.Raw()), &in); err != nil {
                    log.Fatal(err)
                }
                result := fmt.Sprintf("%d", in.A+in.B)
                // 5. NewToolResultBlock(toolUseID, content, isError) builds the
                //    ContentBlockParamUnion for you. block.ID is the tool_use_id.
                toolResults = append(toolResults,
                    anthropic.NewToolResultBlock(block.ID, result, false))
            }
        }

        // 6. Exit when Claude stops asking for tools
        if resp.StopReason != anthropic.StopReasonToolUse {
            break
        }

        // 7. Tool results go in a user message (variadic: all results in one turn)
        messages = append(messages, anthropic.NewUserMessage(toolResults...))
    }
}
```

**Key API surface:**

| Symbol | Purpose |
|---|---|
| `resp.ToParam()` | Convert `Message` response → `MessageParam` for history |
| `block.AsAny().(type)` | Type-switch on `ContentBlockUnion` variants |
| `variant.JSON.Input.Raw()` | Raw JSON string of tool input (for `json.Unmarshal`) |
| `anthropic.NewToolResultBlock(id, content, isError)` | Build `tool_result` block |
| `anthropic.NewUserMessage(blocks...)` | Wrap tool results as a user turn |
| `anthropic.StopReasonToolUse` | `StopReason` constant to check loop termination |
| `anthropic.ToolUnionParam{OfTool: &t}` | Wrap `ToolParam` in the union for `Tools:` |

---

## Thinking

Enable Claude's internal reasoning by setting `Thinking` in `MessageNewParams`. The response will contain `ThinkingBlock` content before the final `TextBlock`.

**Adaptive thinking is the recommended mode for Claude 4.6+ models.** Claude decides dynamically when and how much to think. Combine with the `effort` parameter for cost-quality control.

Derived from `anthropic-sdk-go/message.go` (`ThinkingConfigParamUnion`, `ThinkingConfigAdaptiveParam`).

```go
// There is no ThinkingConfigParamOfAdaptive helper — construct the union
// struct-literal directly and take the address of the variant.
adaptive := anthropic.ThinkingConfigAdaptiveParam{}
params := anthropic.MessageNewParams{
    Model:     anthropic.ModelClaudeSonnet4_6,
    MaxTokens: 16000,
    Thinking:  anthropic.ThinkingConfigParamUnion{OfAdaptive: &adaptive},
    Messages: []anthropic.MessageParam{
        anthropic.NewUserMessage(anthropic.NewTextBlock("How many r's in strawberry?")),
    },
}

resp, err := client.Messages.New(context.Background(), params)
if err != nil {
    log.Fatal(err)
}

// ThinkingBlock(s) precede TextBlock in content
for _, block := range resp.Content {
    switch b := block.AsAny().(type) {
    case anthropic.ThinkingBlock:
        fmt.Println("[thinking]", b.Thinking)
    case anthropic.TextBlock:
        fmt.Println(b.Text)
    }
}
```

> **Deprecated:** `ThinkingConfigParamOfEnabled(budgetTokens)` (fixed-budget extended thinking) still works on Claude 4.6 but is deprecated. Use adaptive thinking above.

To disable: `anthropic.ThinkingConfigParamUnion{OfDisabled: &anthropic.ThinkingConfigDisabledParam{}}`.

---

## Prompt Caching

`System` is `[]TextBlockParam`; set `CacheControl` on the last block to cache tools + system together. For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.

```go
System: []anthropic.TextBlockParam{{
    Text:         longSystemPrompt,
    CacheControl: anthropic.NewCacheControlEphemeralParam(), // default 5m TTL
}},
```

For 1-hour TTL: `anthropic.CacheControlEphemeralParam{TTL: anthropic.CacheControlEphemeralTTLTTL1h}`. There's also a top-level `CacheControl` on `MessageNewParams` that auto-places on the last cacheable block.

Verify hits via `resp.Usage.CacheCreationInputTokens` / `resp.Usage.CacheReadInputTokens`.

---

## Server-Side Tools

Version-suffixed struct names with `Param` suffix. `Name`/`Type` are `constant.*` types — zero value marshals correctly, so `{}` works. Wrap in `ToolUnionParam` with the matching `Of*` field.

```go
Tools: []anthropic.ToolUnionParam{
    {OfWebSearchTool20260209: &anthropic.WebSearchTool20260209Param{}},
    {OfBashTool20250124: &anthropic.ToolBash20250124Param{}},
    {OfTextEditor20250728: &anthropic.ToolTextEditor20250728Param{}},
    {OfCodeExecutionTool20260120: &anthropic.CodeExecutionTool20260120Param{}},
},
```

Also available: `WebFetchTool20260209Param`, `MemoryTool20250818Param`, `ToolSearchToolBm25_20251119Param`, `ToolSearchToolRegex20251119Param`. For the advisor tool, use `BetaAdvisorTool20260301Param` in the beta namespace.

---

## Stop Details

When `StopReason` is `anthropic.StopReasonRefusal`, the response includes structured `StopDetails`:

```go
if resp.StopReason == anthropic.StopReasonRefusal {
    fmt.Println("Category:", resp.StopDetails.Category)     // "cyber" | "bio" | ""
    fmt.Println("Explanation:", resp.StopDetails.Explanation)
}
```

---

## PDF / Document Input

`NewDocumentBlock` generic helper accepts any source type. `MediaType`/`Type` are auto-set.

```go
b64 := base64.StdEncoding.EncodeToString(pdfBytes)

msg := anthropic.NewUserMessage(
    anthropic.NewDocumentBlock(anthropic.Base64PDFSourceParam{Data: b64}),
    anthropic.NewTextBlock("Summarize this document"),
)
```

Other sources: `URLPDFSourceParam{URL: "https://..."}`, `PlainTextSourceParam{Data: "..."}`.

---

## Files API (Beta)

Under `client.Beta.Files`. Method is **`Upload`** (NOT `New`/`Create`), params struct is `BetaFileUploadParams`. The `File` field takes an `io.Reader`; use `anthropic.File()` to attach a filename + content-type for the multipart encoding.

```go
f, _ := os.Open("./upload_me.txt")
defer f.Close()

meta, err := client.Beta.Files.Upload(ctx, anthropic.BetaFileUploadParams{
    File:  anthropic.File(f, "upload_me.txt", "text/plain"),
    Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaFilesAPI2025_04_14},
})
// meta.ID is the file_id to reference in subsequent message requests
```

Other `Beta.Files` methods: `List`, `Delete`, `Download`, `GetMetadata`.

---

## Context Editing / Compaction (Beta)

Use `Beta.Messages.New` with `ContextManagement` on `BetaMessageNewParams`. There is no `NewBetaAssistantMessage` — use `.ToParam()` for the round-trip.

```go
params := anthropic.BetaMessageNewParams{
    Model:     anthropic.ModelClaudeOpus4_6,  // also supported: ModelClaudeSonnet4_6
    MaxTokens: 16000,
    Betas:     []anthropic.AnthropicBeta{"compact-2026-01-12"},
    ContextManagement: anthropic.BetaContextManagementConfigParam{
        Edits: []anthropic.BetaContextManagementConfigEditUnionParam{
            {OfCompact20260112: &anthropic.BetaCompact20260112EditParam{}},
        },
    },
    Messages: []anthropic.BetaMessageParam{ /* ... */ },
}

resp, err := client.Beta.Messages.New(ctx, params)
if err != nil {
    log.Fatal(err)
}

// Round-trip: append response to history via .ToParam()
params.Messages = append(params.Messages, resp.ToParam())

// Read compaction blocks from the response
for _, block := range resp.Content {
    if c, ok := block.AsAny().(anthropic.BetaCompactionBlock); ok {
        fmt.Println("compaction summary:", c.Content)
    }
}
```

Other edit types: `BetaClearToolUses20250919EditParam`, `BetaClearThinking20251015EditParam`.

FILE:go/managed-agents/README.md
# Managed Agents — Go

> **Bindings not shown here:** This README covers the most common managed-agents flows for Go. If you need a class, method, namespace, field, or behavior that isn't shown, WebFetch the Go SDK repo **or the relevant docs page** from `shared/live-sources.md` rather than guess. Do not extrapolate from cURL shapes or another language's SDK.

> **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `agents.New` and pass it to every subsequent `sessions.New`; do not call `agents.New` in the request path. The Anthropic CLI is one convenient way to create agents and environments from version-controlled YAML — its URL is in `shared/live-sources.md`. The examples below show in-code creation for completeness; in production the create call belongs in setup, not in the request path.

## Installation

```bash
go get github.com/anthropics/anthropic-sdk-go
```

## Client Initialization

```go
import (
    "context"

    "github.com/anthropics/anthropic-sdk-go"
    "github.com/anthropics/anthropic-sdk-go/option"
)

// Default (uses ANTHROPIC_API_KEY env var)
client := anthropic.NewClient()

// Explicit API key
client := anthropic.NewClient(
    option.WithAPIKey("your-api-key"),
)

ctx := context.Background()
```

---

## Create an Environment

```go
environment, err := client.Beta.Environments.New(ctx, anthropic.BetaEnvironmentNewParams{
    Name: "my-dev-env",
    Config: anthropic.BetaCloudConfigParams{
        Networking: anthropic.BetaCloudConfigParamsNetworkingUnion{
            OfUnrestricted: &anthropic.UnrestrictedNetworkParam{},
        },
    },
})
if err != nil {
    panic(err)
}
fmt.Println(environment.ID) // env_...
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** `Model`/`System`/`Tools` live on the agent object, not the session. Always start with `Beta.Agents.New()` — the session only takes `Agent: anthropic.BetaSessionNewParamsAgentUnion{OfString: anthropic.String(agent.ID)}` (or the typed `OfBetaManagedAgentsAgents` variant when you need a specific version).

### Minimal

```go
// 1. Create the agent (reusable, versioned)
agent, err := client.Beta.Agents.New(ctx, anthropic.BetaAgentNewParams{
    Name: "Coding Assistant",
    Model: anthropic.BetaManagedAgentsModelConfigParams{
        ID:   "claude-opus-4-8",
        Type: anthropic.BetaManagedAgentsModelConfigParamsTypeModelConfig,
    },
    System: anthropic.String("You are a helpful coding assistant."),
    Tools: []anthropic.BetaAgentNewParamsToolUnion{{
        OfAgentToolset20260401: &anthropic.BetaManagedAgentsAgentToolset20260401Params{
            Type: anthropic.BetaManagedAgentsAgentToolset20260401ParamsTypeAgentToolset20260401,
        },
    }},
})
if err != nil {
    panic(err)
}

// 2. Start a session
session, err := client.Beta.Sessions.New(ctx, anthropic.BetaSessionNewParams{
    Agent: anthropic.BetaSessionNewParamsAgentUnion{
        OfBetaManagedAgentsAgents: &anthropic.BetaManagedAgentsAgentParams{
            Type:    anthropic.BetaManagedAgentsAgentParamsTypeAgent,
            ID:      agent.ID,
            Version: anthropic.Int(agent.Version),
        },
    },
    EnvironmentID: environment.ID,
    Title:         anthropic.String("Quickstart session"),
})
if err != nil {
    panic(err)
}
fmt.Printf("Session ID: %s, status: %s\n", session.ID, session.Status)
```

### Updating an Agent

Updates create new versions; the agent object is immutable per version.

```go
updatedAgent, err := client.Beta.Agents.Update(ctx, agent.ID, anthropic.BetaAgentUpdateParams{
    Version: agent.Version,
    System:  anthropic.String("You are a helpful coding agent. Always write tests."),
})
if err != nil {
    panic(err)
}
fmt.Printf("New version: %d\n", updatedAgent.Version)

// List all versions
iter := client.Beta.Agents.Versions.ListAutoPaging(ctx, agent.ID, anthropic.BetaAgentVersionListParams{})
for iter.Next() {
    version := iter.Current()
    fmt.Printf("Version %d: %s\n", version.Version, version.UpdatedAt.Format(time.RFC3339))
}
if err := iter.Err(); err != nil {
    panic(err)
}

// Archive the agent
_, err = client.Beta.Agents.Archive(ctx, agent.ID, anthropic.BetaAgentArchiveParams{})
if err != nil {
    panic(err)
}
```

---

## Send a User Message

```go
_, err = client.Beta.Sessions.Events.Send(ctx, session.ID, anthropic.BetaSessionEventSendParams{
    Events: []anthropic.SendEventsParamsUnion{{
        OfUserMessage: &anthropic.BetaManagedAgentsUserMessageEventParams{
            Type: anthropic.BetaManagedAgentsUserMessageEventParamsTypeUserMessage,
            Content: []anthropic.BetaManagedAgentsUserMessageEventParamsContentUnion{{
                OfText: &anthropic.BetaManagedAgentsTextBlockParam{
                    Type: anthropic.BetaManagedAgentsTextBlockTypeText,
                    Text: "Review the auth module",
                },
            }},
        },
    }},
})
if err != nil {
    panic(err)
}
```

> 💡 **Stream-first:** Open the stream *before* (or concurrently with) sending the message. The stream only delivers events that occur after it opens — stream-after-send means early events arrive buffered in one batch. See [Steering Patterns](../../shared/managed-agents-events.md#steering-patterns).

---

## Stream Events (SSE)

```go
// Open the stream first, then send the user message
stream := client.Beta.Sessions.Events.StreamEvents(ctx, session.ID, anthropic.BetaSessionEventStreamParams{})
defer stream.Close()

if _, err := client.Beta.Sessions.Events.Send(ctx, session.ID, anthropic.BetaSessionEventSendParams{
    Events: []anthropic.SendEventsParamsUnion{{
        OfUserMessage: &anthropic.BetaManagedAgentsUserMessageEventParams{
            Type: anthropic.BetaManagedAgentsUserMessageEventParamsTypeUserMessage,
            Content: []anthropic.BetaManagedAgentsUserMessageEventParamsContentUnion{{
                OfText: &anthropic.BetaManagedAgentsTextBlockParam{
                    Type: anthropic.BetaManagedAgentsTextBlockTypeText,
                    Text: "Summarize the repo README",
                },
            }},
        },
    }},
}); err != nil {
    panic(err)
}

events:
for stream.Next() {
    switch event := stream.Current().AsAny().(type) {
    case anthropic.BetaManagedAgentsAgentMessageEvent:
        for _, block := range event.Content {
            fmt.Print(block.Text)
        }
    case anthropic.BetaManagedAgentsAgentToolUseEvent:
        fmt.Printf("\n[Using tool: %s]\n", event.Name)
    case anthropic.BetaManagedAgentsSessionStatusIdleEvent:
        break events
    case anthropic.BetaManagedAgentsSessionErrorEvent:
        fmt.Printf("\n[Error: %s]\n", event.Error.Message)
        break events
    }
}
if err := stream.Err(); err != nil {
    panic(err)
}
```

### Reconnecting and Tailing

When reconnecting mid-session, list past events first to dedupe, then tail live events:

```go
stream := client.Beta.Sessions.Events.StreamEvents(ctx, session.ID, anthropic.BetaSessionEventStreamParams{})
defer stream.Close()

// Stream is open and buffering. List history before tailing live.
seenEventIDs := map[string]struct{}{}
history := client.Beta.Sessions.Events.ListAutoPaging(ctx, session.ID, anthropic.BetaSessionEventListParams{})
for history.Next() {
    seenEventIDs[history.Current().ID] = struct{}{}
}
if err := history.Err(); err != nil {
    panic(err)
}

// Tail live events, skipping anything already seen
tail:
for stream.Next() {
    event := stream.Current()
    if _, seen := seenEventIDs[event.ID]; seen {
        continue
    }
    seenEventIDs[event.ID] = struct{}{}
    switch event := event.AsAny().(type) {
    case anthropic.BetaManagedAgentsAgentMessageEvent:
        for _, block := range event.Content {
            fmt.Print(block.Text)
        }
    case anthropic.BetaManagedAgentsSessionStatusIdleEvent:
        break tail
    }
}
if err := stream.Err(); err != nil {
    panic(err)
}
```

---

## Provide Custom Tool Result

> ℹ️ The Go managed-agents bindings for `user.custom_tool_result` are not yet documented in this skill or in the apps source examples. Refer to `shared/managed-agents-events.md` for the wire format and the `github.com/anthropics/anthropic-sdk-go` repository for the corresponding Go params types.

---

## Poll Events

```go
// Auto-paginating iterator
iter := client.Beta.Sessions.Events.ListAutoPaging(ctx, session.ID, anthropic.BetaSessionEventListParams{})
for iter.Next() {
    event := iter.Current()
    fmt.Printf("%s: %s\n", event.Type, event.ID)
}
if err := iter.Err(); err != nil {
    panic(err)
}
```

---

## Upload a File

```go
csvFile, err := os.Open("data.csv")
if err != nil {
    panic(err)
}
defer csvFile.Close()

file, err := client.Beta.Files.Upload(ctx, anthropic.BetaFileUploadParams{
    File: csvFile,
})
if err != nil {
    panic(err)
}
fmt.Printf("File ID: %s\n", file.ID)

// Mount in a session
session, err := client.Beta.Sessions.New(ctx, anthropic.BetaSessionNewParams{
    Agent: anthropic.BetaSessionNewParamsAgentUnion{
        OfString: anthropic.String(agent.ID),
    },
    EnvironmentID: environment.ID,
    Resources: []anthropic.BetaSessionNewParamsResourceUnion{{
        OfFile: &anthropic.BetaManagedAgentsFileResourceParams{
            Type:      anthropic.BetaManagedAgentsFileResourceParamsTypeFile,
            FileID:    file.ID,
            MountPath: anthropic.String("/workspace/data.csv"),
        },
    }},
})
if err != nil {
    panic(err)
}
```

### Add and Manage Resources on an Existing Session

```go
// Attach an additional file to an open session
resource, err := client.Beta.Sessions.Resources.Add(ctx, session.ID, anthropic.BetaSessionResourceAddParams{
    BetaManagedAgentsFileResourceParams: anthropic.BetaManagedAgentsFileResourceParams{
        Type:   anthropic.BetaManagedAgentsFileResourceParamsTypeFile,
        FileID: file.ID,
    },
})
if err != nil {
    panic(err)
}
fmt.Println(resource.ID) // "sesrsc_01ABC..."

// List resources on the session
listed, err := client.Beta.Sessions.Resources.List(ctx, session.ID, anthropic.BetaSessionResourceListParams{})
if err != nil {
    panic(err)
}
for _, entry := range listed.Data {
    fmt.Println(entry.ID, entry.Type)
}

// Detach a resource
if _, err := client.Beta.Sessions.Resources.Delete(ctx, resource.ID, anthropic.BetaSessionResourceDeleteParams{
    SessionID: session.ID,
}); err != nil {
    panic(err)
}
```

---

## List and Download Session Files

> ℹ️ Listing and downloading files an agent wrote during a session is not yet documented for Go in this skill or in the apps source examples. See `shared/managed-agents-events.md` and the `github.com/anthropics/anthropic-sdk-go` repository for the `Beta.Files.List` and `Beta.Files.Download` Go params types.

---

## Session Management

```go
// List environments
environments, err := client.Beta.Environments.List(ctx, anthropic.BetaEnvironmentListParams{})
if err != nil {
    panic(err)
}

// Retrieve a specific environment
env, err := client.Beta.Environments.Get(ctx, environment.ID, anthropic.BetaEnvironmentGetParams{})
if err != nil {
    panic(err)
}

// Archive an environment (read-only, existing sessions continue)
_, err = client.Beta.Environments.Archive(ctx, environment.ID, anthropic.BetaEnvironmentArchiveParams{})
if err != nil {
    panic(err)
}

// Delete an environment (only if no sessions reference it)
_, err = client.Beta.Environments.Delete(ctx, environment.ID, anthropic.BetaEnvironmentDeleteParams{})
if err != nil {
    panic(err)
}

// Delete a session
_, err = client.Beta.Sessions.Delete(ctx, session.ID, anthropic.BetaSessionDeleteParams{})
if err != nil {
    panic(err)
}
```

---

## MCP Server Integration

```go
// Agent declares MCP server (no auth here — auth goes in a vault)
agent, err := client.Beta.Agents.New(ctx, anthropic.BetaAgentNewParams{
    Name: "GitHub Assistant",
    Model: anthropic.BetaManagedAgentsModelConfigParams{
        ID:   "claude-opus-4-8",
        Type: anthropic.BetaManagedAgentsModelConfigParamsTypeModelConfig,
    },
    MCPServers: []anthropic.BetaManagedAgentsUrlmcpServerParams{{
        Type: anthropic.BetaManagedAgentsUrlmcpServerParamsTypeURL,
        Name: "github",
        URL:  "https://api.githubcopilot.com/mcp/",
    }},
    Tools: []anthropic.BetaAgentNewParamsToolUnion{
        {
            OfAgentToolset20260401: &anthropic.BetaManagedAgentsAgentToolset20260401Params{
                Type: anthropic.BetaManagedAgentsAgentToolset20260401ParamsTypeAgentToolset20260401,
            },
        },
        {
            OfMCPToolset: &anthropic.BetaManagedAgentsMCPToolsetParams{
                Type:          anthropic.BetaManagedAgentsMCPToolsetParamsTypeMCPToolset,
                MCPServerName: "github",
            },
        },
    },
})
if err != nil {
    panic(err)
}

// Session attaches vault(s) containing credentials for those MCP server URLs
session, err := client.Beta.Sessions.New(ctx, anthropic.BetaSessionNewParams{
    Agent: anthropic.BetaSessionNewParamsAgentUnion{
        OfBetaManagedAgentsAgents: &anthropic.BetaManagedAgentsAgentParams{
            Type:    anthropic.BetaManagedAgentsAgentParamsTypeAgent,
            ID:      agent.ID,
            Version: anthropic.Int(agent.Version),
        },
    },
    EnvironmentID: environment.ID,
    VaultIDs:      []string{vault.ID},
})
if err != nil {
    panic(err)
}
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

---

## Vaults

```go
// Create a vault
vault, err := client.Beta.Vaults.New(ctx, anthropic.BetaVaultNewParams{
    DisplayName: "Alice",
    Metadata:    map[string]string{"external_user_id": "usr_abc123"},
})
if err != nil {
    panic(err)
}

// Add an OAuth credential
credential, err := client.Beta.Vaults.Credentials.New(ctx, vault.ID, anthropic.BetaVaultCredentialNewParams{
    DisplayName: anthropic.String("Alice's Slack"),
    Auth: anthropic.BetaVaultCredentialNewParamsAuthUnion{
        OfMCPOAuth: &anthropic.BetaManagedAgentsMCPOAuthCreateParams{
            Type:         anthropic.BetaManagedAgentsMCPOAuthCreateParamsTypeMCPOAuth,
            MCPServerURL: "https://mcp.slack.com/mcp",
            AccessToken:  "xoxp-...",
            ExpiresAt:    anthropic.Time(time.Date(2026, time.April, 15, 0, 0, 0, 0, time.UTC)),
            Refresh: anthropic.BetaManagedAgentsMCPOAuthRefreshParams{
                TokenEndpoint: "https://slack.com/api/oauth.v2.access",
                ClientID:      "1234567890.0987654321",
                Scope:         anthropic.String("channels:read chat:write"),
                RefreshToken:  "xoxe-1-...",
                TokenEndpointAuth: anthropic.BetaManagedAgentsMCPOAuthRefreshParamsTokenEndpointAuthUnion{
                    OfClientSecretPost: &anthropic.BetaManagedAgentsTokenEndpointAuthPostParam{
                        Type:         anthropic.BetaManagedAgentsTokenEndpointAuthPostParamTypeClientSecretPost,
                        ClientSecret: "abc123...",
                    },
                },
            },
        },
    },
})
if err != nil {
    panic(err)
}

// Rotate the credential (e.g., after a token refresh)
_, err = client.Beta.Vaults.Credentials.Update(ctx, credential.ID, anthropic.BetaVaultCredentialUpdateParams{
    VaultID: vault.ID,
    Auth: anthropic.BetaVaultCredentialUpdateParamsAuthUnion{
        OfMCPOAuth: &anthropic.BetaManagedAgentsMCPOAuthUpdateParams{
            Type:        anthropic.BetaManagedAgentsMCPOAuthUpdateParamsTypeMCPOAuth,
            AccessToken: anthropic.String("xoxp-new-..."),
            ExpiresAt:   anthropic.Time(time.Date(2026, time.May, 15, 0, 0, 0, 0, time.UTC)),
            Refresh: anthropic.BetaManagedAgentsMCPOAuthRefreshUpdateParams{
                RefreshToken: anthropic.String("xoxe-1-new-..."),
            },
        },
    },
})
if err != nil {
    panic(err)
}

// Archive a vault
_, err = client.Beta.Vaults.Archive(ctx, vault.ID, anthropic.BetaVaultArchiveParams{})
if err != nil {
    panic(err)
}
```

---

## GitHub Repository Integration

Mount a GitHub repository as a session resource (a vault holds the GitHub MCP credential):

```go
session, err := client.Beta.Sessions.New(ctx, anthropic.BetaSessionNewParams{
    Agent:         anthropic.BetaSessionNewParamsAgentUnion{OfString: anthropic.String(agent.ID)},
    EnvironmentID: environment.ID,
    VaultIDs:      []string{vault.ID},
    Resources: []anthropic.BetaSessionNewParamsResourceUnion{
        {
            OfGitHubRepository: &anthropic.BetaManagedAgentsGitHubRepositoryResourceParams{
                Type:               anthropic.BetaManagedAgentsGitHubRepositoryResourceParamsTypeGitHubRepository,
                URL:                "https://github.com/org/repo",
                MountPath:          anthropic.String("/workspace/repo"),
                AuthorizationToken: "ghp_your_github_token",
            },
        },
    },
})
if err != nil {
    panic(err)
}
```

Multiple repositories on the same session:

```go
resources := []anthropic.BetaSessionNewParamsResourceUnion{
    {
        OfGitHubRepository: &anthropic.BetaManagedAgentsGitHubRepositoryResourceParams{
            Type:               anthropic.BetaManagedAgentsGitHubRepositoryResourceParamsTypeGitHubRepository,
            URL:                "https://github.com/org/frontend",
            MountPath:          anthropic.String("/workspace/frontend"),
            AuthorizationToken: "ghp_your_github_token",
        },
    },
    {
        OfGitHubRepository: &anthropic.BetaManagedAgentsGitHubRepositoryResourceParams{
            Type:               anthropic.BetaManagedAgentsGitHubRepositoryResourceParamsTypeGitHubRepository,
            URL:                "https://github.com/org/backend",
            MountPath:          anthropic.String("/workspace/backend"),
            AuthorizationToken: "ghp_your_github_token",
        },
    },
}
```

Rotating a repository's authorization token:

```go
listed, err := client.Beta.Sessions.Resources.List(ctx, session.ID, anthropic.BetaSessionResourceListParams{})
if err != nil {
    panic(err)
}
repoResourceID := listed.Data[0].ID

_, err = client.Beta.Sessions.Resources.Update(ctx, repoResourceID, anthropic.BetaSessionResourceUpdateParams{
    SessionID:          session.ID,
    AuthorizationToken: "ghp_your_new_github_token",
})
if err != nil {
    panic(err)
}
```

FILE:java/claude-api.md
# Claude API — Java

> **Note:** The Java SDK supports the Claude API and beta tool use with annotated classes. Agent SDK is not yet available for Java.

## Installation

Maven:

```xml
<dependency>
    <groupId>com.anthropic</groupId>
    <artifactId>anthropic-java</artifactId>
    <version>2.34.0</version>
</dependency>
```

Gradle:

```groovy
implementation("com.anthropic:anthropic-java:2.34.0")
```

## Client Initialization

```java
import com.anthropic.client.AnthropicClient;
import com.anthropic.client.okhttp.AnthropicOkHttpClient;

// Default (reads ANTHROPIC_API_KEY from environment)
AnthropicClient client = AnthropicOkHttpClient.fromEnv();

// Explicit API key
AnthropicClient client = AnthropicOkHttpClient.builder()
    .apiKey("your-api-key")
    .build();
```

---

## Basic Message Request

```java
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Message;
import com.anthropic.models.messages.Model;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(16000L)
    .addUserMessage("What is the capital of France?")
    .build();

Message response = client.messages().create(params);
response.content().stream()
    .flatMap(block -> block.text().stream())
    .forEach(textBlock -> System.out.println(textBlock.text()));
```

---

## Streaming

```java
import com.anthropic.core.http.StreamResponse;
import com.anthropic.models.messages.RawMessageStreamEvent;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(64000L)
    .addUserMessage("Write a haiku")
    .build();

try (StreamResponse<RawMessageStreamEvent> streamResponse = client.messages().createStreaming(params)) {
    streamResponse.stream()
        .flatMap(event -> event.contentBlockDelta().stream())
        .flatMap(deltaEvent -> deltaEvent.delta().text().stream())
        .forEach(textDelta -> System.out.print(textDelta.text()));
}
```

---

## Thinking

**Adaptive thinking is the recommended mode for Claude 4.6+ models.** Claude decides dynamically when and how much to think. The builder has a direct `.thinking(ThinkingConfigAdaptive)` overload — no manual union wrapping.

```java
import com.anthropic.models.messages.ContentBlock;
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Model;
import com.anthropic.models.messages.ThinkingConfigAdaptive;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_SONNET_4_6)
    .maxTokens(16000L)
    .thinking(ThinkingConfigAdaptive.builder().build())
    .addUserMessage("Solve this step by step: 27 * 453")
    .build();

for (ContentBlock block : client.messages().create(params).content()) {
    block.thinking().ifPresent(t -> System.out.println("[thinking] " + t.thinking()));
    block.text().ifPresent(t -> System.out.println(t.text()));
}
```

> **Deprecated:** `ThinkingConfigEnabled.builder().budgetTokens(N)` (and the `.enabledThinking(N)` shortcut) still works on Claude 4.6 but is deprecated. Use adaptive thinking above.

`ContentBlock` narrowing: `.thinking()` / `.text()` return `Optional<T>` — use `.ifPresent(...)` or `.stream().flatMap(...)`. Alternative: `isThinking()` / `asThinking()` boolean+unwrap pairs (throws on wrong variant).

---

## Tool Use (Beta)

The Java SDK supports beta tool use with annotated classes. Tool classes implement `Supplier<String>` for automatic execution via `BetaToolRunner`.

### Tool Runner (automatic loop)

```java
import com.anthropic.models.beta.messages.MessageCreateParams;
import com.anthropic.models.beta.messages.BetaMessage;
import com.anthropic.helpers.BetaToolRunner;
import com.fasterxml.jackson.annotation.JsonClassDescription;
import com.fasterxml.jackson.annotation.JsonPropertyDescription;
import java.util.function.Supplier;

@JsonClassDescription("Get the weather in a given location")
static class GetWeather implements Supplier<String> {
    @JsonPropertyDescription("The city and state, e.g. San Francisco, CA")
    public String location;

    @Override
    public String get() {
        return "The weather in " + location + " is sunny and 72°F";
    }
}

BetaToolRunner toolRunner = client.beta().messages().toolRunner(
    MessageCreateParams.builder()
        .model("claude-opus-4-8")
        .maxTokens(16000L)
        .putAdditionalHeader("anthropic-beta", "structured-outputs-2025-11-13")
        .addTool(GetWeather.class)
        .addUserMessage("What's the weather in San Francisco?")
        .build());

for (BetaMessage message : toolRunner) {
    System.out.println(message);
}
```

### Memory Tool

The Java SDK provides `BetaMemoryToolHandler` for implementing the memory tool backend. You supply a handler that manages file storage, and the `BetaToolRunner` handles memory tool calls automatically.

```java
import com.anthropic.helpers.BetaMemoryToolHandler;
import com.anthropic.helpers.BetaToolRunner;
import com.anthropic.models.beta.messages.BetaMemoryTool20250818;
import com.anthropic.models.beta.messages.BetaMessage;
import com.anthropic.models.beta.messages.MessageCreateParams;
import com.anthropic.models.beta.messages.ToolRunnerCreateParams;

// Implement BetaMemoryToolHandler with your storage backend (e.g., filesystem)
BetaMemoryToolHandler memoryHandler = new FileSystemMemoryToolHandler(sandboxRoot);

MessageCreateParams createParams = MessageCreateParams.builder()
    .model("claude-opus-4-8")
    .maxTokens(4096L)
    .addTool(BetaMemoryTool20250818.builder().build())
    .addUserMessage("Remember that my favorite color is blue")
    .build();

BetaToolRunner toolRunner = client.beta().messages().toolRunner(
    ToolRunnerCreateParams.builder()
        .betaMemoryToolHandler(memoryHandler)
        .initialMessageParams(createParams)
        .build());

for (BetaMessage message : toolRunner) {
    System.out.println(message);
}
```

See the [shared memory tool concepts](../shared/tool-use-concepts.md) for more details on the memory tool.

### Non-Beta Tool Declaration (manual JSON schema)

`Tool.InputSchema.Properties` is a freeform `Map<String, JsonValue>` wrapper — build property schemas via `putAdditionalProperty`. `type: "object"` is the default. The builder has a direct `.addTool(Tool)` overload that wraps in `ToolUnion` automatically.

```java
import com.anthropic.core.JsonValue;
import com.anthropic.models.messages.Tool;

Tool tool = Tool.builder()
    .name("get_weather")
    .description("Get the current weather in a given location")
    .inputSchema(Tool.InputSchema.builder()
        .properties(Tool.InputSchema.Properties.builder()
            .putAdditionalProperty("location", JsonValue.from(Map.of("type", "string")))
            .build())
        .required(List.of("location"))
        .build())
    .build();

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_SONNET_4_6)
    .maxTokens(16000L)
    .addTool(tool)
    .addUserMessage("Weather in Paris?")
    .build();
```

For manual tool loops, handle `tool_use` blocks in the response, send `tool_result` back, loop until `stop_reason` is `"end_turn"`. See [shared tool use concepts](../shared/tool-use-concepts.md).

### Building `MessageParam` with Content Blocks (Tool Result Round-Trip)

`MessageParam.Content` is an inner union class (string | list). Use the builder's `.contentOfBlockParams(List<ContentBlockParam>)` alias — there is NO separate `MessageParamContent` class with a static `ofBlockParams`:

```java
import com.anthropic.models.messages.MessageParam;
import com.anthropic.models.messages.ContentBlockParam;
import com.anthropic.models.messages.ToolResultBlockParam;

List<ContentBlockParam> results = List.of(
    ContentBlockParam.ofToolResult(ToolResultBlockParam.builder()
        .toolUseId(toolUseBlock.id())
        .content(yourResultString)
        .build())
);

MessageParam toolResultMsg = MessageParam.builder()
    .role(MessageParam.Role.USER)
    .contentOfBlockParams(results)   // builder alias for Content.ofBlockParams(...)
    .build();
```

---

## Effort Parameter

Effort is nested inside `OutputConfig` — there is NO `.effort()` directly on `MessageCreateParams.Builder`.

```java
import com.anthropic.models.messages.OutputConfig;

.outputConfig(OutputConfig.builder()
    .effort(OutputConfig.Effort.HIGH)  // or LOW, MEDIUM, MAX
    .build())
```

Combine with `Thinking = ThinkingConfigAdaptive` for cost-quality control.

---

## Prompt Caching

System message as a list of `TextBlockParam` with `CacheControlEphemeral`. Use `.systemOfTextBlockParams(...)` — the plain `.system(String)` overload can't carry cache control. For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.

```java
import com.anthropic.models.messages.TextBlockParam;
import com.anthropic.models.messages.CacheControlEphemeral;

.systemOfTextBlockParams(List.of(
    TextBlockParam.builder()
        .text(longSystemPrompt)
        .cacheControl(CacheControlEphemeral.builder()
            .ttl(CacheControlEphemeral.Ttl.TTL_1H)  // optional; also TTL_5M
            .build())
        .build()))
```

There's also a top-level `.cacheControl(CacheControlEphemeral)` on `MessageCreateParams.Builder` and on `Tool.builder()`.

Verify hits via `response.usage().cacheCreationInputTokens()` / `response.usage().cacheReadInputTokens()`.

---

## Token Counting

```java
import com.anthropic.models.messages.MessageCountTokensParams;

long tokens = client.messages().countTokens(
    MessageCountTokensParams.builder()
        .model(Model.CLAUDE_SONNET_4_6)
        .addUserMessage("Hello")
        .build()
).inputTokens();
```

---

## Structured Output

The class-based overload auto-derives the JSON schema from your POJO and gives you a typed `.text()` return — no manual schema, no manual parsing.

```java
import com.anthropic.models.messages.StructuredMessageCreateParams;

record Book(String title, String author) {}
record BookList(List<Book> books) {}

StructuredMessageCreateParams<BookList> params = MessageCreateParams.builder()
    .model(Model.CLAUDE_SONNET_4_6)
    .maxTokens(16000L)
    .outputConfig(BookList.class)  // returns a typed builder
    .addUserMessage("List 3 classic novels")
    .build();

client.messages().create(params).content().stream()
    .flatMap(cb -> cb.text().stream())
    .forEach(typed -> {
        // typed.text() returns BookList, not String
        for (Book b : typed.text().books()) System.out.println(b.title());
    });
```

Supports Jackson annotations: `@JsonPropertyDescription`, `@JsonIgnore`, `@ArraySchema(minItems=...)`. Manual schema path: `OutputConfig.builder().format(JsonOutputFormat.builder().schema(...).build())`.

---

## PDF / Document Input

`DocumentBlockParam` builder has source shortcuts. Wrap in `ContentBlockParam.ofDocument()` and pass via `.addUserMessageOfBlockParams()`.

```java
import com.anthropic.models.messages.DocumentBlockParam;
import com.anthropic.models.messages.ContentBlockParam;
import com.anthropic.models.messages.TextBlockParam;

DocumentBlockParam doc = DocumentBlockParam.builder()
    .base64Source(base64String)  // or .urlSource("https://...") or .textSource("...")
    .title("My Document")        // optional
    .build();

.addUserMessageOfBlockParams(List.of(
    ContentBlockParam.ofDocument(doc),
    ContentBlockParam.ofText(TextBlockParam.builder().text("Summarize this").build())))
```

---

## Server-Side Tools

Version-suffixed types; `name`/`type` auto-set by builder. Direct `.addTool()` overloads exist for every type — no manual `ToolUnion` wrapping.

```java
import com.anthropic.models.messages.WebSearchTool20260209;
import com.anthropic.models.messages.ToolBash20250124;
import com.anthropic.models.messages.ToolTextEditor20250728;
import com.anthropic.models.messages.CodeExecutionTool20260120;

.addTool(WebSearchTool20260209.builder()
    .maxUses(5L)                              // optional
    .allowedDomains(List.of("example.com"))   // optional
    .build())
.addTool(ToolBash20250124.builder().build())
.addTool(ToolTextEditor20250728.builder().build())
.addTool(CodeExecutionTool20260120.builder().build())
```

Also available: `WebFetchTool20260209`, `MemoryTool20250818`, `ToolSearchToolBm25_20251119`. For the advisor tool, use `BetaAdvisorTool20260301` in the beta namespace.

### Beta namespace (MCP, compaction)

For beta-only features use `com.anthropic.models.beta.messages.*` — class names have a `Beta` prefix AND live in the beta package. The beta `MessageCreateParams.Builder` has direct `.addTool(BetaToolBash20250124)` overloads AND `.addMcpServer()`:

```java
import com.anthropic.models.beta.messages.MessageCreateParams;
import com.anthropic.models.beta.messages.BetaToolBash20250124;
import com.anthropic.models.beta.messages.BetaCodeExecutionTool20260120;
import com.anthropic.models.beta.messages.BetaRequestMcpServerUrlDefinition;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(16000L)
    .addBeta("mcp-client-2025-11-20")
    .addTool(BetaToolBash20250124.builder().build())
    .addTool(BetaCodeExecutionTool20260120.builder().build())
    .addMcpServer(BetaRequestMcpServerUrlDefinition.builder()
        .name("my-server")
        .url("https://example.com/mcp")
        .build())
    .addUserMessage("...")
    .build();

client.beta().messages().create(params);
```

`BetaTool*` types are NOT interchangeable with non-beta `Tool*` — pick one namespace per request.

**Reading server-tool blocks in the response:** `ServerToolUseBlock` has `.id()`, `.name()` (enum), and `._input()` returning raw `JsonValue` — there is NO typed `.input()`. For code execution results, unwrap two levels:

```java
for (ContentBlock block : response.content()) {
    block.serverToolUse().ifPresent(stu -> {
        System.out.println("tool: " + stu.name() + " input: " + stu._input());
    });
    block.codeExecutionToolResult().ifPresent(r -> {
        r.content().resultBlock().ifPresent(result -> {
            System.out.println("stdout: " + result.stdout());
            System.out.println("stderr: " + result.stderr());
            System.out.println("exit: " + result.returnCode());
        });
    });
}
```

---

## Stop Details

When `stopReason()` is `"refusal"`, the response includes structured `stopDetails()`:

```java
response.stopDetails().ifPresent(details -> {
    System.out.println("Category: " + details.category());
    System.out.println("Explanation: " + details.explanation());
});
```

---

## Error Type

`AnthropicServiceException` exposes `.errorType()` returning `Optional<ErrorType>` for programmatic error classification:

```java
try {
    client.messages().create(params);
} catch (AnthropicServiceException e) {
    e.errorType().ifPresent(type ->
        System.out.println("Error type: " + type)  // RATE_LIMIT_ERROR, OVERLOADED_ERROR, etc.
    );
}
```

---

## Files API (Beta)

Under `client.beta().files()`. File references in messages need the beta message types (non-beta `DocumentBlockParam.Source` has no file-ID variant).

```java
import com.anthropic.models.beta.files.FileUploadParams;
import com.anthropic.models.beta.files.FileMetadata;
import com.anthropic.models.beta.messages.BetaRequestDocumentBlock;
import java.nio.file.Paths;

FileMetadata meta = client.beta().files().upload(
    FileUploadParams.builder()
        .file(Paths.get("/path/to/doc.pdf"))  // or .file(InputStream) or .file(byte[])
        .build());

// Reference in a beta message:
BetaRequestDocumentBlock doc = BetaRequestDocumentBlock.builder()
    .fileSource(meta.id())
    .build();
```

Other methods: `.list()`, `.delete(String fileId)`, `.download(String fileId)`, `.retrieveMetadata(String fileId)`.

FILE:java/managed-agents/README.md
# Managed Agents — Java

> **Bindings not shown here:** This README covers the most common managed-agents flows for Java. If you need a class, method, namespace, field, or behavior that isn't shown, WebFetch the Java SDK repo **or the relevant docs page** from `shared/live-sources.md` rather than guess. Do not extrapolate from cURL shapes or another language's SDK.

> **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `client.beta().agents().create` and pass it to every subsequent `client.beta().sessions().create`; do not call `agents().create` in the request path. The Anthropic CLI is one convenient way to create agents and environments from version-controlled YAML — its URL is in `shared/live-sources.md`. The examples below show in-code creation for completeness; in production the create call belongs in setup, not in the request path.

## Installation

```xml
<dependency>
    <groupId>com.anthropic</groupId>
    <artifactId>anthropic-java</artifactId>
</dependency>
```

## Client Initialization

```java
import com.anthropic.client.okhttp.AnthropicOkHttpClient;

// Default (uses ANTHROPIC_API_KEY env var)
var client = AnthropicOkHttpClient.fromEnv();
```

---

## Create an Environment

```java
import com.anthropic.models.beta.environments.BetaCloudConfigParams;
import com.anthropic.models.beta.environments.EnvironmentCreateParams;
import com.anthropic.models.beta.environments.UnrestrictedNetwork;

var environment = client.beta().environments().create(EnvironmentCreateParams.builder()
    .name("my-dev-env")
    .config(BetaCloudConfigParams.builder()
        .networking(UnrestrictedNetwork.builder().build())
        .build())
    .build());
System.out.println("Environment ID: " + environment.id()); // env_...
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** Model, system, and tools live on the agent object, not the session. Always start with `client.beta().agents().create()` — the session takes either `.agent(agent.id())` or the typed `BetaManagedAgentsAgentParams.builder()...build()`.

### Minimal

```java
import com.anthropic.models.beta.agents.AgentCreateParams;
import com.anthropic.models.beta.agents.BetaManagedAgentsAgentToolset20260401Params;
import com.anthropic.models.beta.sessions.BetaManagedAgentsAgentParams;
import com.anthropic.models.beta.sessions.SessionCreateParams;

// 1. Create the agent (reusable, versioned)
var agent = client.beta().agents().create(AgentCreateParams.builder()
    .name("Coding Assistant")
    .model("claude-opus-4-8")
    .system("You are a helpful coding assistant.")
    .addTool(BetaManagedAgentsAgentToolset20260401Params.builder()
        .type(BetaManagedAgentsAgentToolset20260401Params.Type.AGENT_TOOLSET_20260401)
        .build())
    .build());

// 2. Start a session
var session = client.beta().sessions().create(SessionCreateParams.builder()
    .agent(BetaManagedAgentsAgentParams.builder()
        .type(BetaManagedAgentsAgentParams.Type.AGENT)
        .id(agent.id())
        .version(agent.version())
        .build())
    .environmentId(environment.id())
    .title("Quickstart session")
    .build());
System.out.println("Session ID: " + session.id());
```

### Updating an Agent

Updates create new versions; the agent object is immutable per version.

```java
import com.anthropic.models.beta.agents.AgentUpdateParams;

var updatedAgent = client.beta().agents().update(agent.id(), AgentUpdateParams.builder()
    .version(agent.version())
    .system("You are a helpful coding agent. Always write tests.")
    .build());
System.out.println("New version: " + updatedAgent.version());

// List all versions
for (var version : client.beta().agents().versions().list(agent.id()).autoPager()) {
    System.out.println("Version " + version.version() + ": " + version.updatedAt());
}

// Archive the agent
var archived = client.beta().agents().archive(agent.id());
System.out.println("Archived at: " + archived.archivedAt().orElseThrow());
```

---

## Send a User Message

```java
import com.anthropic.models.beta.sessions.events.BetaManagedAgentsUserMessageEventParams;
import com.anthropic.models.beta.sessions.events.EventSendParams;

client.beta().sessions().events().send(session.id(), EventSendParams.builder()
    .addEvent(BetaManagedAgentsUserMessageEventParams.builder()
        .type(BetaManagedAgentsUserMessageEventParams.Type.USER_MESSAGE)
        .addTextContent("Review the auth module")
        .build())
    .build());
```

> 💡 **Stream-first:** Open the stream *before* (or concurrently with) sending the message. The stream only delivers events that occur after it opens — stream-after-send means early events arrive buffered in one batch. See [Steering Patterns](../../shared/managed-agents-events.md#steering-patterns).

---

## Stream Events (SSE)

```java
import com.anthropic.models.beta.sessions.events.StreamEvents;

// Open the stream first, then send the user message
try (var stream = client.beta().sessions().events().streamStreaming(session.id())) {
    client.beta().sessions().events().send(session.id(), EventSendParams.builder()
        .addEvent(BetaManagedAgentsUserMessageEventParams.builder()
            .type(BetaManagedAgentsUserMessageEventParams.Type.USER_MESSAGE)
            .addTextContent("Summarize the repo README")
            .build())
        .build());

    for (var event : (Iterable<StreamEvents>) stream.stream()::iterator) {
        if (event.isAgentMessage()) {
            event.asAgentMessage().content().forEach(block -> System.out.print(block.text()));
        } else if (event.isAgentToolUse()) {
            System.out.println("\n[Using tool: " + event.asAgentToolUse().name() + "]");
        } else if (event.isSessionStatusIdle()) {
            break;
        } else if (event.isSessionError()) {
            System.out.println("\n[Error]");
            break;
        }
    }
}
```

### Reconnecting and Tailing

When reconnecting mid-session, list past events first to dedupe, then tail live events. The cross-variant `id` field is read from the raw `_json()` value:

```java
import com.anthropic.core.JsonValue;
import java.util.HashSet;
import java.util.Map;
import java.util.Optional;

try (var stream = client.beta().sessions().events().streamStreaming(session.id())) {
    // Stream is open and buffering. List history before tailing live.
    var seenEventIds = new HashSet<String>();
    for (var past : client.beta().sessions().events().list(session.id()).autoPager()) {
        Optional<Map<String, JsonValue>> obj = past._json().orElseThrow().asObject();
        seenEventIds.add(obj.orElseThrow().get("id").asStringOrThrow());
    }

    // Tail live events, skipping anything already seen
    for (var event : (Iterable<StreamEvents>) stream.stream()::iterator) {
        Optional<Map<String, JsonValue>> obj = event._json().orElseThrow().asObject();
        if (!seenEventIds.add(obj.orElseThrow().get("id").asStringOrThrow())) continue;
        if (event.isAgentMessage()) {
            event.asAgentMessage().content().forEach(block -> System.out.print(block.text()));
        } else if (event.isSessionStatusIdle()) {
            break;
        }
    }
}
```

---

## Provide Custom Tool Result

> ℹ️ The Java managed-agents bindings for `user.custom_tool_result` are not yet documented in this skill or in the apps source examples. Refer to `shared/managed-agents-events.md` for the wire format and the `anthropic-java` repository for the corresponding params types.

---

## Poll Events

```java
for (var event : client.beta().sessions().events().list(session.id()).autoPager()) {
    System.out.println(event.type() + ": " + event);
}
```

---

## Upload a File

```java
import com.anthropic.models.beta.files.FileUploadParams;
import com.anthropic.models.beta.sessions.BetaManagedAgentsFileResourceParams;
import java.nio.file.Path;

var dataCsv = Path.of("data.csv");

var file = client.beta().files().upload(FileUploadParams.builder()
    .file(dataCsv)
    .build());
System.out.println("File ID: " + file.id());

// Mount in a session
var session = client.beta().sessions().create(SessionCreateParams.builder()
    .agent(agent.id())
    .environmentId(environment.id())
    .addResource(BetaManagedAgentsFileResourceParams.builder()
        .type(BetaManagedAgentsFileResourceParams.Type.FILE)
        .fileId(file.id())
        .mountPath("/workspace/data.csv")
        .build())
    .build());
```

### Add and Manage Resources on an Existing Session

```java
import com.anthropic.models.beta.sessions.resources.ResourceAddParams;
import com.anthropic.models.beta.sessions.resources.ResourceDeleteParams;

// Attach an additional file to an open session
var resource = client.beta().sessions().resources().add(session.id(), ResourceAddParams.builder()
    .betaManagedAgentsFileResourceParams(BetaManagedAgentsFileResourceParams.builder()
        .type(BetaManagedAgentsFileResourceParams.Type.FILE)
        .fileId(file.id())
        .build())
    .build());
System.out.println(resource.id()); // "sesrsc_01ABC..."

// List resources on the session — entries are a discriminated union
var listed = client.beta().sessions().resources().list(session.id());
for (var entry : listed.data()) {
    if (entry.isFile()) {
        var fileResource = entry.asFile();
        System.out.println(fileResource.id() + " " + fileResource.type());
    } else if (entry.isGitHubRepository()) {
        var repoResource = entry.asGitHubRepository();
        System.out.println(repoResource.id() + " " + repoResource.type());
    }
}

// Detach a resource
client.beta().sessions().resources().delete(resource.id(), ResourceDeleteParams.builder()
    .sessionId(session.id())
    .build());
```

---

## List and Download Session Files

> ℹ️ Listing and downloading files an agent wrote during a session is not yet documented for Java in this skill or in the apps source examples. See `shared/managed-agents-events.md` and the `anthropic-java` repository for the file list/download bindings.

---

## Session Management

```java
// List environments
var environments = client.beta().environments().list();

// Retrieve a specific environment
var env = client.beta().environments().retrieve(environment.id());

// Archive an environment (read-only, existing sessions continue)
client.beta().environments().archive(environment.id());

// Delete an environment (only if no sessions reference it)
client.beta().environments().delete(environment.id());

// Delete a session
client.beta().sessions().delete(session.id());
```

---

## MCP Server Integration

```java
import com.anthropic.models.beta.agents.BetaManagedAgentsMcpToolsetParams;
import com.anthropic.models.beta.agents.BetaManagedAgentsUrlmcpServerParams;

// Agent declares MCP server (no auth here — auth goes in a vault)
var agent = client.beta().agents().create(AgentCreateParams.builder()
    .name("GitHub Assistant")
    .model("claude-opus-4-8")
    .addMcpServer(BetaManagedAgentsUrlmcpServerParams.builder()
        .type(BetaManagedAgentsUrlmcpServerParams.Type.URL)
        .name("github")
        .url("https://api.githubcopilot.com/mcp/")
        .build())
    .addTool(BetaManagedAgentsAgentToolset20260401Params.builder()
        .type(BetaManagedAgentsAgentToolset20260401Params.Type.AGENT_TOOLSET_20260401)
        .build())
    .addTool(BetaManagedAgentsMcpToolsetParams.builder()
        .type(BetaManagedAgentsMcpToolsetParams.Type.MCP_TOOLSET)
        .mcpServerName("github")
        .build())
    .build());

// Session attaches vault(s) containing credentials for those MCP server URLs
var session = client.beta().sessions().create(SessionCreateParams.builder()
    .agent(BetaManagedAgentsAgentParams.builder()
        .type(BetaManagedAgentsAgentParams.Type.AGENT)
        .id(agent.id())
        .version(agent.version())
        .build())
    .environmentId(environment.id())
    .addVaultId(vault.id())
    .build());
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

---

## Vaults

```java
import com.anthropic.core.JsonValue;
import com.anthropic.models.beta.vaults.VaultCreateParams;
import com.anthropic.models.beta.vaults.credentials.BetaManagedAgentsMcpOAuthCreateParams;
import com.anthropic.models.beta.vaults.credentials.BetaManagedAgentsMcpOAuthRefreshParams;
import com.anthropic.models.beta.vaults.credentials.BetaManagedAgentsMcpOAuthRefreshUpdateParams;
import com.anthropic.models.beta.vaults.credentials.BetaManagedAgentsMcpOAuthUpdateParams;
import com.anthropic.models.beta.vaults.credentials.CredentialCreateParams;
import com.anthropic.models.beta.vaults.credentials.CredentialUpdateParams;
import java.time.OffsetDateTime;

// Create a vault
var vault = client.beta().vaults().create(VaultCreateParams.builder()
    .displayName("Alice")
    .metadata(VaultCreateParams.Metadata.builder()
        .putAdditionalProperty("external_user_id", JsonValue.from("usr_abc123"))
        .build())
    .build());
System.out.println(vault.id()); // "vlt_01ABC..."

// Add an OAuth credential
var credential = client.beta().vaults().credentials().create(vault.id(),
    CredentialCreateParams.builder()
        .displayName("Alice's Slack")
        .auth(BetaManagedAgentsMcpOAuthCreateParams.builder()
            .type(BetaManagedAgentsMcpOAuthCreateParams.Type.MCP_OAUTH)
            .mcpServerUrl("https://mcp.slack.com/mcp")
            .accessToken("xoxp-...")
            .expiresAt(OffsetDateTime.parse("2026-04-15T00:00:00Z"))
            .refresh(BetaManagedAgentsMcpOAuthRefreshParams.builder()
                .tokenEndpoint("https://slack.com/api/oauth.v2.access")
                .clientId("1234567890.0987654321")
                .scope("channels:read chat:write")
                .refreshToken("xoxe-1-...")
                .clientSecretPostTokenEndpointAuth("abc123...")
                .build())
            .build())
        .build());

// Rotate the credential (e.g., after a token refresh)
client.beta().vaults().credentials().update(credential.id(),
    CredentialUpdateParams.builder()
        .vaultId(vault.id())
        .auth(BetaManagedAgentsMcpOAuthUpdateParams.builder()
            .type(BetaManagedAgentsMcpOAuthUpdateParams.Type.MCP_OAUTH)
            .accessToken("xoxp-new-...")
            .expiresAt(OffsetDateTime.parse("2026-05-15T00:00:00Z"))
            .refresh(BetaManagedAgentsMcpOAuthRefreshUpdateParams.builder()
                .refreshToken("xoxe-1-new-...")
                .build())
            .build())
        .build());

// Archive a vault
client.beta().vaults().archive(vault.id());
```

---

## GitHub Repository Integration

Mount a GitHub repository as a session resource (a vault holds the GitHub MCP credential):

```java
import com.anthropic.models.beta.sessions.BetaManagedAgentsGitHubRepositoryResourceParams;

var session = client.beta().sessions().create(SessionCreateParams.builder()
    .agent(agent.id())
    .environmentId(environment.id())
    .addVaultId(vault.id())
    .addResource(BetaManagedAgentsGitHubRepositoryResourceParams.builder()
        .type(BetaManagedAgentsGitHubRepositoryResourceParams.Type.GITHUB_REPOSITORY)
        .url("https://github.com/org/repo")
        .mountPath("/workspace/repo")
        .authorizationToken("ghp_your_github_token")
        .build())
    .build());
```

Multiple repositories on the same session:

```java
import java.util.List;

var resources = List.of(
    BetaManagedAgentsGitHubRepositoryResourceParams.builder()
        .type(BetaManagedAgentsGitHubRepositoryResourceParams.Type.GITHUB_REPOSITORY)
        .url("https://github.com/org/frontend")
        .mountPath("/workspace/frontend")
        .authorizationToken("ghp_your_github_token")
        .build(),
    BetaManagedAgentsGitHubRepositoryResourceParams.builder()
        .type(BetaManagedAgentsGitHubRepositoryResourceParams.Type.GITHUB_REPOSITORY)
        .url("https://github.com/org/backend")
        .mountPath("/workspace/backend")
        .authorizationToken("ghp_your_github_token")
        .build());
```

Rotating a repository's authorization token:

```java
import com.anthropic.models.beta.sessions.resources.ResourceUpdateParams;

var listed = client.beta().sessions().resources().list(session.id());
var repoResourceId = listed.data().get(0).asGitHubRepository().id();

client.beta().sessions().resources().update(repoResourceId, ResourceUpdateParams.builder()
    .sessionId(session.id())
    .authorizationToken("ghp_your_new_github_token")
    .build());
```

FILE:php/claude-api.md
# Claude API — PHP

> **Note:** The PHP SDK is the official Anthropic SDK for PHP. A beta tool runner is available via `$client->beta->messages->toolRunner()`. Structured output helpers are supported via `StructuredOutputModel` classes. Agent SDK is not available. Bedrock, Vertex AI, and Foundry clients are supported.

## Installation

```bash
composer require "anthropic-ai/sdk"
```

## Client Initialization

```php
use Anthropic\Client;

// Using API key from environment variable
$client = new Client(apiKey: getenv("ANTHROPIC_API_KEY"));
```

### Amazon Bedrock

```php
use Anthropic\Bedrock;

// Constructor is private — use the static factory. Reads AWS credentials from env.
$client = Bedrock\Client::fromEnvironment(region: 'us-east-1');
```

### Google Vertex AI

```php
use Anthropic\Vertex;

// Constructor is private. Parameter is `location`, not `region`.
$client = Vertex\Client::fromEnvironment(
    location: 'us-east5',
    projectId: 'my-project-id',
);
```

### Anthropic Foundry

```php
use Anthropic\Foundry;

// Constructor is private. baseUrl or resource is required.
$client = Foundry\Client::withCredentials(
    authToken: getenv('ANTHROPIC_FOUNDRY_AUTH_TOKEN'),
    baseUrl: 'https://<resource>.services.ai.azure.com/anthropic',
);
```

---

## Basic Message Request

```php
$message = $client->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    messages: [
        ['role' => 'user', 'content' => 'What is the capital of France?'],
    ],
);

// content is an array of polymorphic blocks (TextBlock, ToolUseBlock,
// ThinkingBlock). Accessing ->text on content[0] without checking the block
// type will throw if the first block is not a TextBlock (e.g., when extended
// thinking is enabled and a ThinkingBlock comes first). Always guard:
foreach ($message->content as $block) {
    if ($block->type === 'text') {
        echo $block->text;
    }
}
```

If you only want the first text block:

```php
foreach ($message->content as $block) {
    if ($block->type === 'text') {
        echo $block->text;
        break;
    }
}
```

---

## Streaming

> **Requires SDK v0.5.0+.** v0.4.0 and earlier used a single `$params` array; calling with named parameters throws `Unknown named parameter $model`. Upgrade: `composer require "anthropic-ai/sdk:^0.7"`

```php
use Anthropic\Messages\RawContentBlockDeltaEvent;
use Anthropic\Messages\TextDelta;

$stream = $client->messages->createStream(
    model: 'claude-opus-4-8',
    maxTokens: 64000,
    messages: [
        ['role' => 'user', 'content' => 'Write a haiku'],
    ],
);

foreach ($stream as $event) {
    if ($event instanceof RawContentBlockDeltaEvent && $event->delta instanceof TextDelta) {
        echo $event->delta->text;
    }
}
```

---

## Tool Use

### Tool Runner (Beta)

**Beta:** The PHP SDK provides a tool runner via `$client->beta->messages->toolRunner()`. Define tools with `BetaRunnableTool` — a definition array plus a `run` closure:

```php
use Anthropic\Lib\Tools\BetaRunnableTool;

$weatherTool = new BetaRunnableTool(
    definition: [
        'name' => 'get_weather',
        'description' => 'Get the current weather for a location.',
        'input_schema' => [
            'type' => 'object',
            'properties' => [
                'location' => ['type' => 'string', 'description' => 'City and state'],
            ],
            'required' => ['location'],
        ],
    ],
    run: function (array $input): string {
        return "The weather in {$input['location']} is sunny and 72°F.";
    },
);

$runner = $client->beta->messages->toolRunner(
    maxTokens: 16000,
    messages: [['role' => 'user', 'content' => 'What is the weather in Paris?']],
    model: 'claude-opus-4-8',
    tools: [$weatherTool],
);

foreach ($runner as $message) {
    foreach ($message->content as $block) {
        if ($block->type === 'text') {
            echo $block->text;
        }
    }
}
```

### Manual Loop

Tools are passed as arrays. **The SDK uses camelCase keys** (`inputSchema`, `toolUseID`, `stopReason`) and auto-maps to the API's snake_case on the wire — since v0.5.0. See [shared tool use concepts](../shared/tool-use-concepts.md) for the loop pattern.

```php
use Anthropic\Messages\ToolUseBlock;

$tools = [
    [
        'name' => 'get_weather',
        'description' => 'Get the current weather in a given location',
        'inputSchema' => [  // camelCase, not input_schema
            'type' => 'object',
            'properties' => [
                'location' => ['type' => 'string', 'description' => 'City and state'],
            ],
            'required' => ['location'],
        ],
    ],
];

$messages = [['role' => 'user', 'content' => 'What is the weather in SF?']];

$response = $client->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    tools: $tools,
    messages: $messages,
);

while ($response->stopReason === 'tool_use') {  // camelCase property
    $toolResults = [];
    foreach ($response->content as $block) {
        if ($block instanceof ToolUseBlock) {
            // $block->name  : string               — tool name to dispatch on
            // $block->input : array<string,mixed>  — parsed JSON input
            // $block->id    : string               — pass back as toolUseID
            $result = executeYourTool($block->name, $block->input);
            $toolResults[] = [
                'type' => 'tool_result',
                'toolUseID' => $block->id,  // camelCase, not tool_use_id
                'content' => $result,
            ];
        }
    }

    // Append assistant turn + user turn with tool results
    $messages[] = ['role' => 'assistant', 'content' => $response->content];
    $messages[] = ['role' => 'user', 'content' => $toolResults];

    $response = $client->messages->create(
        model: 'claude-opus-4-8',
        maxTokens: 16000,
        tools: $tools,
        messages: $messages,
    );
}

// Final text response
foreach ($response->content as $block) {
    if ($block->type === 'text') {
        echo $block->text;
    }
}
```

`$block->type === 'tool_use'` also works; `instanceof ToolUseBlock` narrows for PHPStan.


---

## Extended Thinking

**Adaptive thinking is the recommended mode for Claude 4.6+ models.** Claude decides dynamically when and how much to think.

```php
use Anthropic\Messages\ThinkingBlock;

$message = $client->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    thinking: ['type' => 'adaptive'],
    messages: [
        ['role' => 'user', 'content' => 'Solve: 27 * 453'],
    ],
);

// ThinkingBlock(s) precede TextBlock in content
foreach ($message->content as $block) {
    if ($block instanceof ThinkingBlock) {
        echo "Thinking:\n{$block->thinking}\n\n";
        // $block->signature is an opaque string — preserve verbatim if
        // passing thinking blocks back in multi-turn conversations
    } elseif ($block->type === 'text') {
        echo "Answer: {$block->text}\n";
    }
}
```

> **Deprecated:** `['type' => 'enabled', 'budgetTokens' => N]` (fixed-budget extended thinking) still works on Claude 4.6 but is deprecated. Use adaptive thinking above.

`$block->type === 'thinking'` also works for the check; `instanceof` narrows for PHPStan.

---

## Prompt Caching

`system:` takes an array of text blocks; set `cacheControl` on the last block. Array-shape syntax (camelCase keys) is idiomatic. For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.

```php
$message = $client->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    system: [
        ['type' => 'text', 'text' => $longSystemPrompt, 'cacheControl' => ['type' => 'ephemeral']],
    ],
    messages: [['role' => 'user', 'content' => 'Summarize the key points']],
);
```

For 1-hour TTL: `'cacheControl' => ['type' => 'ephemeral', 'ttl' => '1h']`. There's also a top-level `cacheControl:` on `messages->create(...)` that auto-places on the last cacheable block.

Verify hits via `$message->usage->cacheCreationInputTokens` / `$message->usage->cacheReadInputTokens`.

---

## Structured Outputs

### Using StructuredOutputModel (Recommended)

Define a PHP class implementing `StructuredOutputModel` and pass it as `outputConfig`:

```php
use Anthropic\Lib\Contracts\StructuredOutputModel;
use Anthropic\Lib\Concerns\StructuredOutputModelTrait;
use Anthropic\Lib\Attributes\Constrained;

class Person implements StructuredOutputModel
{
    use StructuredOutputModelTrait;

    #[Constrained(description: 'Full name')]
    public string $name;

    public int $age;

    public ?string $email = null;  // nullable = optional field
}

$message = $client->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    messages: [['role' => 'user', 'content' => 'Generate a profile for Alice, age 30']],
    outputConfig: ['format' => Person::class],
);

$person = $message->parsedOutput();  // Person instance
echo $person->name;
```

Types are inferred from PHP type hints. Use `#[Constrained(description: '...')]` to add descriptions. Nullable properties (`?string`) become optional fields.

### Raw Schema

```php
$message = $client->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    messages: [['role' => 'user', 'content' => 'Extract: John (john@co.com), Enterprise plan']],
    outputConfig: [
        'format' => [
            'type' => 'json_schema',
            'schema' => [
                'type' => 'object',
                'properties' => [
                    'name' => ['type' => 'string'],
                    'email' => ['type' => 'string'],
                    'plan' => ['type' => 'string'],
                ],
                'required' => ['name', 'email', 'plan'],
                'additionalProperties' => false,
            ],
        ],
    ],
);

// First text block contains valid JSON
foreach ($message->content as $block) {
    if ($block->type === 'text') {
        $data = json_decode($block->text, true);
        break;
    }
}
```

---

## Beta Features & Server-Side Tools

**`betas:` is NOT a param on `$client->messages->create()`** — it only exists on the beta namespace. Use it for features that need an explicit opt-in header:

```php
use Anthropic\Beta\Messages\BetaRequestMCPServerURLDefinition;

$response = $client->beta->messages->create(
    model: 'claude-opus-4-8',
    maxTokens: 16000,
    mcpServers: [
        BetaRequestMCPServerURLDefinition::with(
            name: 'my-server',
            url: 'https://example.com/mcp',
        ),
    ],
    betas: ['mcp-client-2025-11-20'],  // only valid on ->beta->messages
    messages: [['role' => 'user', 'content' => 'Use the MCP tools']],
);
```

**Server-side tools** (bash, web_search, text_editor, code_execution) are GA and work on both paths — `Anthropic\Messages\ToolBash20250124` / `WebSearchTool20260209` / `ToolTextEditor20250728` / `CodeExecutionTool20260120` for non-beta, `Anthropic\Beta\Messages\BetaToolBash20250124` / `BetaWebSearchTool20260209` / `BetaToolTextEditor20250728` / `BetaCodeExecutionTool20260120` for beta. No `betas:` header needed for these.

---

## Stop Details

When `stopReason` is `'refusal'`, the response includes structured `stopDetails`:

```php
if ($message->stopReason === 'refusal' && $message->stopDetails !== null) {
    echo "Category: " . $message->stopDetails->category . "\n";     // "cyber" | "bio" | null
    echo "Explanation: " . $message->stopDetails->explanation . "\n";
}
```

---

## Error Type

`APIStatusException` exposes a `->type` property for programmatic error classification:

```php
try {
    $client->messages->create(...);
} catch (\Anthropic\Core\Exceptions\APIStatusException $e) {
    echo $e->type?->value;  // "rate_limit_error", "overloaded_error", etc.
}
```

FILE:php/managed-agents/README.md
# Managed Agents — PHP

> **Bindings not shown here:** This README covers the most common managed-agents flows for PHP. If you need a class, method, namespace, field, or behavior that isn't shown, WebFetch the PHP SDK repo **or the relevant docs page** from `shared/live-sources.md` rather than guess. Do not extrapolate from cURL shapes or another language's SDK.

> **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `$client->beta->agents->create` and pass it to every subsequent `->sessions->create`; do not call `agents->create` in the request path. The Anthropic CLI is one convenient way to create agents and environments from version-controlled YAML — its URL is in `shared/live-sources.md`. The examples below show in-code creation for completeness; in production the create call belongs in setup, not in the request path.

## Installation

```bash
composer require "anthropic-ai/sdk"
```

## Client Initialization

```php
use Anthropic\Client;

// Default (uses ANTHROPIC_API_KEY env var)
$client = new Client();

// Explicit API key
$client = new Client(apiKey: 'your-api-key');
```

---

## Create an Environment

```php
$environment = $client->beta->environments->create(
    name: 'my-dev-env',
    config: ['type' => 'cloud', 'networking' => ['type' => 'unrestricted']],
);
echo "Environment ID: {$environment->id}\n"; // env_...
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** `model`/`system`/`tools` live on the agent object, not the session. Always start with `$client->beta->agents->create()` — the session takes either `agent: $agent->id` or the typed `BetaManagedAgentsAgentParams::with(type: 'agent', id: $agent->id, version: $agent->version)`.

### Minimal

```php
use Anthropic\Beta\Agents\BetaManagedAgentsAgentToolset20260401Params;

// 1. Create the agent (reusable, versioned)
$agent = $client->beta->agents->create(
    name: 'Coding Assistant',
    model: 'claude-opus-4-8',
    system: 'You are a helpful coding assistant.',
    tools: [
        BetaManagedAgentsAgentToolset20260401Params::with(
            type: 'agent_toolset_20260401',
        ),
    ],
);

// 2. Start a session
$session = $client->beta->sessions->create(
    agent: ['type' => 'agent', 'id' => $agent->id, 'version' => $agent->version],
    environmentID: $environment->id,
    title: 'Quickstart session',
);
echo "Session ID: {$session->id}\n";
```

### Updating an Agent

Updates create new versions; the agent object is immutable per version.

```php
$updatedAgent = $client->beta->agents->update(
    $agent->id,
    version: $agent->version,
    system: 'You are a helpful coding agent. Always write tests.',
);
echo "New version: {$updatedAgent->version}\n";

// List all versions
foreach ($client->beta->agents->versions->list($agent->id)->pagingEachItem() as $version) {
    echo "Version {$version->version}: {$version->updatedAt->format(DateTimeInterface::ATOM)}\n";
}

// Archive the agent
$archived = $client->beta->agents->archive($agent->id);
echo "Archived at: {$archived->archivedAt->format(DateTimeInterface::ATOM)}\n";
```

---

## Send a User Message

```php
$client->beta->sessions->events->send(
    $session->id,
    events: [
        [
            'type' => 'user.message',
            'content' => [['type' => 'text', 'text' => 'Review the auth module']],
        ],
    ],
);
```

> 💡 **Stream-first:** Open the stream *before* (or concurrently with) sending the message. The stream only delivers events that occur after it opens — stream-after-send means early events arrive buffered in one batch. See [Steering Patterns](../../shared/managed-agents-events.md#steering-patterns).

---

## Stream Events (SSE)

> ℹ️ **Streaming transporter:** PHP's default buffered PSR-18 client never returns for the open-ended session event stream. Use a streaming Guzzle transporter for `streamStream()` calls — other calls keep the default client.

```php
$streamingClient = new GuzzleHttp\Client(['stream' => true]);

// Open the stream first, then send the user message
$stream = $client->beta->sessions->events->streamStream(
    $session->id,
    requestOptions: ['transporter' => $streamingClient],
);
$client->beta->sessions->events->send(
    $session->id,
    events: [
        [
            'type' => 'user.message',
            'content' => [['type' => 'text', 'text' => 'Summarize the repo README']],
        ],
    ],
);

foreach ($stream as $event) {
    match ($event->type) {
        'agent.message' => array_walk(
            $event->content,
            static fn($block) => $block->type === 'text' ? print($block->text) : null,
        ),
        'agent.tool_use' => print("\n[Using tool: {$event->name}]\n"),
        'session.error' => printf("\n[Error: %s]", $event->error?->message ?? 'unknown'),
        default => null,
    };
    if ($event->type === 'session.status_idle' || $event->type === 'session.error') {
        break;
    }
}
$stream->close();
```

### Reconnecting and Tailing

When reconnecting mid-session, list past events first to dedupe, then tail live events:

```php
$stream = $client->beta->sessions->events->streamStream(
    $session->id,
    requestOptions: ['transporter' => $streamingClient],
);

// Stream is open and buffering. List history before tailing live.
$seenEventIds = [];
foreach ($client->beta->sessions->events->list($session->id)->pagingEachItem() as $event) {
    $seenEventIds[$event->id] = true;
}

// Tail live events, skipping anything already seen
foreach ($stream as $event) {
    if (isset($seenEventIds[$event->id])) {
        continue;
    }
    $seenEventIds[$event->id] = true;
    match ($event->type) {
        'agent.message' => array_walk(
            $event->content,
            static fn($block) => $block->type === 'text' ? print($block->text) : null,
        ),
        default => null,
    };
    if ($event->type === 'session.status_idle') {
        break;
    }
}
$stream->close();
```

---

## Provide Custom Tool Result

> ℹ️ The PHP managed-agents bindings for `user.custom_tool_result` are not yet documented in this skill or in the apps source examples. Refer to `shared/managed-agents-events.md` for the wire format and the `anthropic-ai/sdk` PHP repository for the corresponding params.

---

## Poll Events

```php
foreach ($client->beta->sessions->events->list($session->id)->pagingEachItem() as $event) {
    echo "{$event->type}: {$event->id}\n";
}
```

---

## Upload a File

> ℹ️ **PHP file upload:** The PHP SDK's beta managed-agents file upload binding is not shown in the apps source examples; the canonical PHP example uses raw cURL against `POST /v1/files`. If your codebase prefers the SDK, WebFetch the `anthropic-ai/sdk` PHP repository for the latest binding before writing code.

```php
use Anthropic\Beta\Sessions\BetaManagedAgentsFileResourceParams;

// Raw cURL upload (canonical example from the apps source)
$csvPath = 'data.csv';
$ch = curl_init('https://api.anthropic.com/v1/files');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => [
        'x-api-key: ' . getenv('ANTHROPIC_API_KEY'),
        'anthropic-version: 2023-06-01',
        'anthropic-beta: files-api-2025-04-14',
    ],
    CURLOPT_POSTFIELDS => ['file' => new CURLFile($csvPath, 'text/csv', 'data.csv')],
]);
$file = json_decode(curl_exec($ch));
echo "File ID: {$file->id}\n";

// Mount in a session
$session = $client->beta->sessions->create(
    agent: $agent->id,
    environmentID: $environment->id,
    resources: [
        BetaManagedAgentsFileResourceParams::with(
            type: 'file',
            fileID: $file->id,
            mountPath: '/workspace/data.csv',
        ),
    ],
);
```

### Add and Manage Resources on an Existing Session

```php
// Attach an additional file to an open session
$resource = $client->beta->sessions->resources->add(
    $session->id,
    type: 'file',
    fileID: $file->id,
);
echo "{$resource->id}\n"; // "sesrsc_01ABC..."

// List resources on the session
$listed = $client->beta->sessions->resources->list($session->id);
foreach ($listed->data as $entry) {
    echo "{$entry->id} {$entry->type}\n";
}

// Detach a resource
$client->beta->sessions->resources->delete($resource->id, sessionID: $session->id);
```

---

## List and Download Session Files

> ℹ️ Listing and downloading files an agent wrote during a session is not yet documented for PHP in this skill or in the apps source examples. See `shared/managed-agents-events.md` and the `anthropic-ai/sdk` PHP repository for the file list/download bindings.

---

## Session Management

```php
// List environments
$environments = $client->beta->environments->list();

// Retrieve a specific environment
$env = $client->beta->environments->retrieve($environment->id);

// Archive an environment (read-only, existing sessions continue)
$client->beta->environments->archive($environment->id);

// Delete an environment (only if no sessions reference it)
$client->beta->environments->delete($environment->id);

// Delete a session
$client->beta->sessions->delete($session->id);
```

---

## MCP Server Integration

```php
use Anthropic\Beta\Agents\BetaManagedAgentsAgentToolset20260401Params;
use Anthropic\Beta\Agents\BetaManagedAgentsMCPToolsetParams;
use Anthropic\Beta\Agents\BetaManagedAgentsUrlmcpServerParams;
use Anthropic\Beta\Sessions\BetaManagedAgentsAgentParams;

// Agent declares MCP server (no auth here — auth goes in a vault)
$agent = $client->beta->agents->create(
    name: 'GitHub Assistant',
    model: 'claude-opus-4-8',
    mcpServers: [
        BetaManagedAgentsUrlmcpServerParams::with(
            type: 'url',
            name: 'github',
            url: 'https://api.githubcopilot.com/mcp/',
        ),
    ],
    tools: [
        BetaManagedAgentsAgentToolset20260401Params::with(type: 'agent_toolset_20260401'),
        BetaManagedAgentsMCPToolsetParams::with(
            type: 'mcp_toolset',
            mcpServerName: 'github',
        ),
    ],
);

// Session attaches vault(s) containing credentials for those MCP server URLs
$session = $client->beta->sessions->create(
    agent: BetaManagedAgentsAgentParams::with(
        type: 'agent',
        id: $agent->id,
        version: $agent->version,
    ),
    environmentID: $environment->id,
    vaultIDs: [$vault->id],
);
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

---

## Vaults

```php
// Create a vault
$vault = $client->beta->vaults->create(
    displayName: 'Alice',
    metadata: ['external_user_id' => 'usr_abc123'],
);
echo $vault->id . "\n"; // "vlt_01ABC..."

// Add an OAuth credential
$credential = $client->beta->vaults->credentials->create(
    vaultID: $vault->id,
    displayName: "Alice's Slack",
    auth: [
        'type' => 'mcp_oauth',
        'mcp_server_url' => 'https://mcp.slack.com/mcp',
        'access_token' => 'xoxp-...',
        'expires_at' => '2026-04-15T00:00:00Z',
        'refresh' => [
            'token_endpoint' => 'https://slack.com/api/oauth.v2.access',
            'client_id' => '1234567890.0987654321',
            'scope' => 'channels:read chat:write',
            'refresh_token' => 'xoxe-1-...',
            'token_endpoint_auth' => [
                'type' => 'client_secret_post',
                'client_secret' => 'abc123...',
            ],
        ],
    ],
);

// Rotate the credential (e.g., after a token refresh)
$client->beta->vaults->credentials->update(
    $credential->id,
    vaultID: $vault->id,
    auth: [
        'type' => 'mcp_oauth',
        'access_token' => 'xoxp-new-...',
        'expires_at' => '2026-05-15T00:00:00Z',
        'refresh' => ['refresh_token' => 'xoxe-1-new-...'],
    ],
);

// Archive a vault
$client->beta->vaults->archive($vault->id);
```

---

## GitHub Repository Integration

Mount a GitHub repository as a session resource (a vault holds the GitHub MCP credential):

```php
$session = $client->beta->sessions->create(
    agent: $agent->id,
    environmentID: $environment->id,
    vaultIDs: [$vault->id],
    resources: [
        [
            'type' => 'github_repository',
            'url' => 'https://github.com/org/repo',
            'mountPath' => '/workspace/repo',
            'authorizationToken' => 'ghp_your_github_token',
        ],
    ],
);
```

Multiple repositories on the same session:

```php
$resources = [
    [
        'type' => 'github_repository',
        'url' => 'https://github.com/org/frontend',
        'mountPath' => '/workspace/frontend',
        'authorizationToken' => 'ghp_your_github_token',
    ],
    [
        'type' => 'github_repository',
        'url' => 'https://github.com/org/backend',
        'mountPath' => '/workspace/backend',
        'authorizationToken' => 'ghp_your_github_token',
    ],
];
```

Rotating a repository's authorization token:

```php
$listed = $client->beta->sessions->resources->list($session->id);
$repoResourceId = $listed->data[0]->id;

$client->beta->sessions->resources->update(
    $repoResourceId,
    sessionID: $session->id,
    authorizationToken: 'ghp_your_new_github_token',
);
```

FILE:python/claude-api/batches.md
# Message Batches API — Python

The Batches API (`POST /v1/messages/batches`) processes Messages API requests asynchronously at 50% of standard prices.

## Key Facts

- Up to 100,000 requests or 256 MB per batch
- Most batches complete within 1 hour; maximum 24 hours
- Results available for 29 days after creation
- 50% cost reduction on all token usage
- All Messages API features supported (vision, tools, caching, etc.)

---

## Create a Batch

```python
import anthropic
from anthropic.types.message_create_params import MessageCreateParamsNonStreaming
from anthropic.types.messages.batch_create_params import Request

client = anthropic.Anthropic()

message_batch = client.messages.batches.create(
    requests=[
        Request(
            custom_id="request-1",
            params=MessageCreateParamsNonStreaming(
                model="claude-opus-4-8",
                max_tokens=16000,
                messages=[{"role": "user", "content": "Summarize climate change impacts"}]
            )
        ),
        Request(
            custom_id="request-2",
            params=MessageCreateParamsNonStreaming(
                model="claude-opus-4-8",
                max_tokens=16000,
                messages=[{"role": "user", "content": "Explain quantum computing basics"}]
            )
        ),
    ]
)

print(f"Batch ID: {message_batch.id}")
print(f"Status: {message_batch.processing_status}")
```

---

## Poll for Completion

```python
import time

while True:
    batch = client.messages.batches.retrieve(message_batch.id)
    if batch.processing_status == "ended":
        break
    print(f"Status: {batch.processing_status}, processing: {batch.request_counts.processing}")
    time.sleep(60)

print("Batch complete!")
print(f"Succeeded: {batch.request_counts.succeeded}")
print(f"Errored: {batch.request_counts.errored}")
```

---

## Retrieve Results

> **Note:** Examples below use `match/case` syntax, requiring Python 3.10+. For earlier versions, use `if/elif` chains instead.

```python
for result in client.messages.batches.results(message_batch.id):
    match result.result.type:
        case "succeeded":
            msg = result.result.message
            text = next((b.text for b in msg.content if b.type == "text"), "")
            print(f"[{result.custom_id}] {text[:100]}")
        case "errored":
            if result.result.error.type == "invalid_request":
                print(f"[{result.custom_id}] Validation error - fix request and retry")
            else:
                print(f"[{result.custom_id}] Server error - safe to retry")
        case "canceled":
            print(f"[{result.custom_id}] Canceled")
        case "expired":
            print(f"[{result.custom_id}] Expired - resubmit")
```

---

## Cancel a Batch

```python
cancelled = client.messages.batches.cancel(message_batch.id)
print(f"Status: {cancelled.processing_status}")  # "canceling"
```

---

## List Batches (auto-pagination)

Iterating the return value of any `list()` call auto-paginates across all pages — do not index into `.data` if you want the full set:

```python
for batch in client.messages.batches.list(limit=20):
    print(batch.id, batch.processing_status)
```

For manual control, use `first_page.has_next_page()` / `first_page.get_next_page()` / `first_page.next_page_info()`; `first_page.data` holds the current page's items and `first_page.last_id` is the cursor.

---

## Batch with Prompt Caching

```python
shared_system = [
    {"type": "text", "text": "You are a literary analyst."},
    {
        "type": "text",
        "text": large_document_text,  # Shared across all requests
        "cache_control": {"type": "ephemeral"}
    }
]

message_batch = client.messages.batches.create(
    requests=[
        Request(
            custom_id=f"analysis-{i}",
            params=MessageCreateParamsNonStreaming(
                model="claude-opus-4-8",
                max_tokens=16000,
                system=shared_system,
                messages=[{"role": "user", "content": question}]
            )
        )
        for i, question in enumerate(questions)
    ]
)
```

---

## Full End-to-End Example

```python
import anthropic
import time
from anthropic.types.message_create_params import MessageCreateParamsNonStreaming
from anthropic.types.messages.batch_create_params import Request

client = anthropic.Anthropic()

# 1. Prepare requests
items_to_classify = [
    "The product quality is excellent!",
    "Terrible customer service, never again.",
    "It's okay, nothing special.",
]

requests = [
    Request(
        custom_id=f"classify-{i}",
        params=MessageCreateParamsNonStreaming(
            model="claude-haiku-4-5",
            max_tokens=50,
            messages=[{
                "role": "user",
                "content": f"Classify as positive/negative/neutral (one word): {text}"
            }]
        )
    )
    for i, text in enumerate(items_to_classify)
]

# 2. Create batch
batch = client.messages.batches.create(requests=requests)
print(f"Created batch: {batch.id}")

# 3. Wait for completion
while True:
    batch = client.messages.batches.retrieve(batch.id)
    if batch.processing_status == "ended":
        break
    time.sleep(10)

# 4. Collect results
results = {}
for result in client.messages.batches.results(batch.id):
    if result.result.type == "succeeded":
        msg = result.result.message
        results[result.custom_id] = next((b.text for b in msg.content if b.type == "text"), "")

for custom_id, classification in sorted(results.items()):
    print(f"{custom_id}: {classification}")
```

FILE:python/claude-api/files-api.md
# Files API — Python

The Files API uploads files for use in Messages API requests. Reference files via `file_id` in content blocks, avoiding re-uploads across multiple API calls.

**Beta:** Pass `betas=["files-api-2025-04-14"]` in your API calls (the SDK sets the required header automatically).

## Key Facts

- Maximum file size: 500 MB
- Total storage: 100 GB per organization
- Files persist until deleted
- File operations (upload, list, delete) are free; content used in messages is billed as input tokens
- Not available on Amazon Bedrock or Google Vertex AI

---

## Upload a File

The `file` argument accepts a `(filename, content, content_type)` tuple, a `pathlib.Path` (or any `PathLike` — read for you, async-safe with `AsyncAnthropic`), or an open binary file object.

```python
import anthropic
from pathlib import Path

client = anthropic.Anthropic()

uploaded = client.beta.files.upload(
    file=("report.pdf", open("report.pdf", "rb"), "application/pdf"),
)
# or: client.beta.files.upload(file=Path("report.pdf"))
print(f"File ID: {uploaded.id}")
print(f"Size: {uploaded.size_bytes} bytes")
```

---

## Use a File in Messages

### PDF / Text Document

```python
response = client.beta.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": [
            {"type": "text", "text": "Summarize the key findings in this report."},
            {
                "type": "document",
                "source": {"type": "file", "file_id": uploaded.id},
                "title": "Q4 Report",           # optional
                "citations": {"enabled": True}   # optional, enables citations
            }
        ]
    }],
    betas=["files-api-2025-04-14"],
)
for block in response.content:
    if block.type == "text":
        print(block.text)
```

### Image

```python
image_file = client.beta.files.upload(
    file=("photo.png", open("photo.png", "rb"), "image/png"),
)

response = client.beta.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": [
            {"type": "text", "text": "What's in this image?"},
            {
                "type": "image",
                "source": {"type": "file", "file_id": image_file.id}
            }
        ]
    }],
    betas=["files-api-2025-04-14"],
)
```

---

## Manage Files

### List Files

Iterate the list result directly — the SDK auto-paginates across all pages. Only use `.data` if you want the first page only.

```python
for f in client.beta.files.list():
    print(f"{f.id}: {f.filename} ({f.size_bytes} bytes)")
```

### Get File Metadata

```python
file_info = client.beta.files.retrieve_metadata("file_011CNha8iCJcU1wXNR6q4V8w")
print(f"Filename: {file_info.filename}")
print(f"MIME type: {file_info.mime_type}")
```

### Delete a File

```python
client.beta.files.delete("file_011CNha8iCJcU1wXNR6q4V8w")
```

### Download a File

Only files created by the code execution tool or skills can be downloaded (not user-uploaded files).

```python
file_content = client.beta.files.download("file_011CNha8iCJcU1wXNR6q4V8w")
file_content.write_to_file("output.txt")
```

---

## Full End-to-End Example

Upload a document once, ask multiple questions about it:

```python
import anthropic

client = anthropic.Anthropic()

# 1. Upload once
uploaded = client.beta.files.upload(
    file=("contract.pdf", open("contract.pdf", "rb"), "application/pdf"),
)
print(f"Uploaded: {uploaded.id}")

# 2. Ask multiple questions using the same file_id
questions = [
    "What are the key terms and conditions?",
    "What is the termination clause?",
    "Summarize the payment schedule.",
]

for question in questions:
    response = client.beta.messages.create(
        model="claude-opus-4-8",
        max_tokens=16000,
        messages=[{
            "role": "user",
            "content": [
                {"type": "text", "text": question},
                {
                    "type": "document",
                    "source": {"type": "file", "file_id": uploaded.id}
                }
            ]
        }],
        betas=["files-api-2025-04-14"],
    )
    print(f"\nQ: {question}")
    text = next((b.text for b in response.content if b.type == "text"), "")
    print(f"A: {text[:200]}")

# 3. Clean up when done
client.beta.files.delete(uploaded.id)
```

FILE:python/claude-api/README.md
# Claude API — Python

## Installation

```bash
pip install anthropic
```

## Client Initialization

```python
import anthropic

# Default — resolves credentials from the environment:
# ANTHROPIC_API_KEY, or ANTHROPIC_AUTH_TOKEN, or an `ant auth login` profile.
# Prefer this for local dev; don't hardcode a key.
client = anthropic.Anthropic()

# Explicit API key (only when you must inject a specific key)
client = anthropic.Anthropic(api_key="your-api-key")

# Async client
async_client = anthropic.AsyncAnthropic()
```

---

## Client Configuration

### Per-request overrides

Use `with_options()` to override client settings for a single call without mutating the client:

```python
client.with_options(timeout=5.0, max_retries=5).messages.create(
    model="claude-opus-4-8",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}],
)
```

### Timeouts

Default request timeout is 10 minutes. Pass a float (seconds) or an `httpx.Timeout` for granular control. On timeout the SDK raises `anthropic.APITimeoutError` (and retries per `max_retries`).

```python
import httpx

client = anthropic.Anthropic(timeout=20.0)
client = anthropic.Anthropic(
    timeout=httpx.Timeout(60.0, read=5.0, write=10.0, connect=2.0),
)
```

### Retries

The SDK auto-retries connection errors, 408, 409, 429, and ≥500 with exponential backoff (default 2 retries). Set `max_retries` on the client or via `with_options()`; `max_retries=0` disables.

### Async performance (aiohttp backend)

For high-concurrency async workloads, install `anthropic[aiohttp]` and pass `DefaultAioHttpClient` instead of the default httpx backend:

```python
from anthropic import AsyncAnthropic, DefaultAioHttpClient

async with AsyncAnthropic(http_client=DefaultAioHttpClient()) as client:
    ...
```

### Custom HTTP client (proxy, base URL)

Use `DefaultHttpxClient` / `DefaultAsyncHttpxClient` — not raw `httpx.Client` — so the SDK's default timeouts and connection limits are preserved:

```python
from anthropic import Anthropic, DefaultHttpxClient

client = Anthropic(
    base_url="http://my.test.server.example.com:8083",  # or ANTHROPIC_BASE_URL env var
    http_client=DefaultHttpxClient(proxy="http://my.test.proxy.example.com"),
)
```

### Logging

Set `ANTHROPIC_LOG=debug` (or `info`) to enable SDK logging via the standard `logging` module.

---

## Basic Message Request

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[
        {"role": "user", "content": "What is the capital of France?"}
    ]
)
# response.content is a list of content block objects (TextBlock, ThinkingBlock,
# ToolUseBlock, ...). Check .type before accessing .text.
for block in response.content:
    if block.type == "text":
        print(block.text)
```

---

## System Prompts

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    system="You are a helpful coding assistant. Always provide examples in Python.",
    messages=[{"role": "user", "content": "How do I read a JSON file?"}]
)
```

### Mid-conversation system messages (beta, model-gated)

For operator instructions that arrive mid-conversation (mode switches, injected state), append `{"role": "system", ...}` to `messages` instead of editing top-level `system` — this preserves the cached prefix and carries operator authority. Must follow a user message; cannot be `messages[0]`. Unsupported models return a 400 (`role 'system' is not supported on this model`). See `shared/prompt-caching.md` for when to use this vs. top-level `system`.

```python
response = client.messages.create(
    model=MODEL_ID,  # must support mid-conversation system messages
    max_tokens=16000,
    system=[{"type": "text", "text": STABLE_SYSTEM, "cache_control": {"type": "ephemeral"}}],
    messages=history + [
        {"role": "user", "content": user_message},
        {"role": "system", "content": "Terse mode enabled — keep responses under 40 words."},
    ],
    extra_headers={"anthropic-beta": "mid-conversation-system-2026-04-07"},
)
```

---

## Vision (Images)

### Base64

```python
import base64

with open("image.png", "rb") as f:
    image_data = base64.standard_b64encode(f.read()).decode("utf-8")

response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": [
            {
                "type": "image",
                "source": {
                    "type": "base64",
                    "media_type": "image/png",
                    "data": image_data
                }
            },
            {"type": "text", "text": "What's in this image?"}
        ]
    }]
)
```

### URL

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": [
            {
                "type": "image",
                "source": {
                    "type": "url",
                    "url": "https://example.com/image.png"
                }
            },
            {"type": "text", "text": "Describe this image"}
        ]
    }]
)
```

---

## Prompt Caching

Cache large context to reduce costs (up to 90% savings). **Caching is a prefix match** — any byte change anywhere in the prefix invalidates everything after it. For placement patterns, architectural guidance (frozen system prompt, deterministic tool order, where to put volatile content), and the silent-invalidator audit checklist, read `shared/prompt-caching.md`.

### Automatic Caching (Recommended)

Use top-level `cache_control` to automatically cache the last cacheable block in the request — no need to annotate individual content blocks:

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    cache_control={"type": "ephemeral"},  # auto-caches the last cacheable block
    system="You are an expert on this large document...",
    messages=[{"role": "user", "content": "Summarize the key points"}]
)
```

### Manual Cache Control

For fine-grained control, add `cache_control` to specific content blocks:

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    system=[{
        "type": "text",
        "text": "You are an expert on this large document...",
        "cache_control": {"type": "ephemeral"}  # default TTL is 5 minutes
    }],
    messages=[{"role": "user", "content": "Summarize the key points"}]
)

# With explicit TTL (time-to-live)
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    system=[{
        "type": "text",
        "text": "You are an expert on this large document...",
        "cache_control": {"type": "ephemeral", "ttl": "1h"}  # 1 hour TTL
    }],
    messages=[{"role": "user", "content": "Summarize the key points"}]
)
```

### Verifying Cache Hits

```python
print(response.usage.cache_creation_input_tokens)  # tokens written to cache (~1.25x cost)
print(response.usage.cache_read_input_tokens)      # tokens served from cache (~0.1x cost)
print(response.usage.input_tokens)                 # uncached tokens (full cost)
```

If `cache_read_input_tokens` is zero across repeated identical-prefix requests, a silent invalidator is at work — `datetime.now()` or a UUID in the system prompt, unsorted `json.dumps()`, or a varying tool set. See `shared/prompt-caching.md` for the full audit table.

---

## Extended Thinking

> **Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6:** Use adaptive thinking. `budget_tokens` is removed on Fable 5, Opus 4.8, and 4.7 (400 if sent); deprecated on Opus 4.6 and Sonnet 4.6.
> **Older models:** Use `thinking: {type: "enabled", budget_tokens: N}` (must be < `max_tokens`, min 1024).

```python
# Fable 5 / Opus 4.8 / 4.7 / 4.6: adaptive thinking (recommended)
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    thinking={"type": "adaptive"},
    output_config={"effort": "high"},  # low | medium | high | max
    messages=[{"role": "user", "content": "Solve this step by step..."}]
)

# Access thinking and response
for block in response.content:
    if block.type == "thinking":
        print(f"Thinking: {block.thinking}")
    elif block.type == "text":
        print(f"Response: {block.text}")
```

---

## Error Handling

```python
import anthropic

try:
    response = client.messages.create(...)
except anthropic.BadRequestError as e:
    print(f"Bad request: {e.message}")
except anthropic.AuthenticationError:
    print("Invalid API key")
except anthropic.PermissionDeniedError:
    print("API key lacks required permissions")
except anthropic.NotFoundError:
    print("Invalid model or endpoint")
except anthropic.RateLimitError as e:
    retry_after = int(e.response.headers.get("retry-after", "60"))
    print(f"Rate limited. Retry after {retry_after}s.")
except anthropic.APIStatusError as e:
    if e.status_code >= 500:
        print(f"Server error ({e.status_code}). Retry later.")
    else:
        print(f"API error: {e.message}")
except anthropic.APIConnectionError:
    print("Network error. Check internet connection.")
```

---

## Response Helpers

Every response object exposes `_request_id` (populated from the `request-id` header) — log it when reporting failures to Anthropic. Despite the underscore prefix, this property is public.

```python
message = client.messages.create(...)
print(message._request_id)       # req_018EeWyXxfu5pfWkrYcMdjWG
print(message.to_json())          # serialize the Pydantic model
print(message.to_dict())          # plain dict
```

To access raw headers or other response metadata, use `.with_raw_response`:

```python
raw = client.messages.with_raw_response.create(
    model="claude-opus-4-8",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}],
)
print(raw.headers.get("request-id"))
message = raw.parse()  # the Message object messages.create() would have returned
```

---

## Multi-Turn Conversations

The API is stateless — send the full conversation history each time.

```python
class ConversationManager:
    """Manage multi-turn conversations with the Claude API."""

    def __init__(self, client: anthropic.Anthropic, model: str, system: str = None):
        self.client = client
        self.model = model
        self.system = system
        self.messages = []

    def send(self, user_message: str, **kwargs) -> str:
        """Send a message and get a response."""
        self.messages.append({"role": "user", "content": user_message})

        response = self.client.messages.create(
            model=self.model,
            max_tokens=kwargs.get("max_tokens", 16000),
            system=self.system,
            messages=self.messages,
            **kwargs
        )

        assistant_message = next(
            (b.text for b in response.content if b.type == "text"), ""
        )
        self.messages.append({"role": "assistant", "content": assistant_message})

        return assistant_message

# Usage
conversation = ConversationManager(
    client=anthropic.Anthropic(),
    model="claude-opus-4-8",
    system="You are a helpful assistant."
)

response1 = conversation.send("My name is Alice.")
response2 = conversation.send("What's my name?")  # Claude remembers "Alice"
```

**Rules:**

- Consecutive same-role messages are allowed — the API combines them into a single turn
- First message must be `user`
- `role: "system"` messages are allowed mid-conversation under the `mid-conversation-system-2026-04-07` beta on supporting models — see § Mid-conversation system messages above

---

### Compaction (long conversations)

> **Beta, Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6.** When conversations approach the 200K context window, compaction automatically summarizes earlier context server-side. The API returns a `compaction` block; you must pass it back on subsequent requests — append `response.content`, not just the text.

```python
import anthropic

client = anthropic.Anthropic()
messages = []

def chat(user_message: str) -> str:
    messages.append({"role": "user", "content": user_message})

    response = client.beta.messages.create(
        betas=["compact-2026-01-12"],
        model="claude-opus-4-8",
        max_tokens=16000,
        messages=messages,
        context_management={
            "edits": [{"type": "compact_20260112"}]
        }
    )

    # Append full content — compaction blocks must be preserved
    messages.append({"role": "assistant", "content": response.content})

    return next(block.text for block in response.content if block.type == "text")

# Compaction triggers automatically when context grows large
print(chat("Help me build a Python web scraper"))
print(chat("Add support for JavaScript-rendered pages"))
print(chat("Now add rate limiting and error handling"))
```

---

## Stop Reasons

The `stop_reason` field in the response indicates why the model stopped generating:

| Value | Meaning |
|-------|---------|
| `end_turn` | Claude finished its response naturally |
| `max_tokens` | Hit the `max_tokens` limit — increase it or use streaming |
| `stop_sequence` | Hit a custom stop sequence |
| `tool_use` | Claude wants to call a tool — execute it and continue |
| `pause_turn` | Model paused and can be resumed (agentic flows) |
| `refusal` | Claude refused for safety reasons — check `stop_details` |

### Structured Stop Details

When `stop_reason` is `"refusal"`, the response includes a `stop_details` object with structured information about the refusal:

```python
if response.stop_reason == "refusal" and response.stop_details:
    print(f"Category: {response.stop_details.category}")   # "cyber" | "bio" | None
    print(f"Explanation: {response.stop_details.explanation}")
```

---

## Cost Optimization Strategies

### 1. Use Prompt Caching for Repeated Context

```python
# Automatic caching (simplest — caches the last cacheable block)
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    cache_control={"type": "ephemeral"},
    system=large_document_text,  # e.g., 50KB of context
    messages=[{"role": "user", "content": "Summarize the key points"}]
)

# First request: full cost
# Subsequent requests: ~90% cheaper for cached portion
```

### 2. Choose the Right Model

```python
# Default to Opus for most tasks
response = client.messages.create(
    model="claude-opus-4-8",  # $5.00/$25.00 per 1M tokens
    max_tokens=16000,
    messages=[{"role": "user", "content": "Explain quantum computing"}]
)

# Use Sonnet for high-volume production workloads
standard_response = client.messages.create(
    model="claude-sonnet-4-6",  # $3.00/$15.00 per 1M tokens
    max_tokens=16000,
    messages=[{"role": "user", "content": "Summarize this document"}]
)

# Use Haiku only for simple, speed-critical tasks
simple_response = client.messages.create(
    model="claude-haiku-4-5",  # $1.00/$5.00 per 1M tokens
    max_tokens=256,
    messages=[{"role": "user", "content": "Classify this as positive or negative"}]
)
```

### 3. Use Token Counting Before Requests

```python
count_response = client.messages.count_tokens(
    model="claude-opus-4-8",
    messages=messages,
    system=system
)

estimated_input_cost = count_response.input_tokens * 0.000005  # $5/1M tokens
print(f"Estimated input cost: .4f")
```

---

## Retry with Exponential Backoff

> **Note:** The Anthropic SDK automatically retries rate limit (429) and server errors (5xx) with exponential backoff. You can configure this with `max_retries` (default: 2). Only implement custom retry logic if you need behavior beyond what the SDK provides.

```python
import time
import random
import anthropic

def call_with_retry(
    client: anthropic.Anthropic,
    max_retries: int = 5,
    base_delay: float = 1.0,
    max_delay: float = 60.0,
    **kwargs
):
    """Call the API with exponential backoff retry."""
    last_exception = None

    for attempt in range(max_retries):
        try:
            return client.messages.create(**kwargs)
        except anthropic.RateLimitError as e:
            last_exception = e
        except anthropic.APIStatusError as e:
            if e.status_code >= 500:
                last_exception = e
            else:
                raise  # Client errors (4xx except 429) should not be retried

        delay = min(base_delay * (2 ** attempt) + random.uniform(0, 1), max_delay)
        print(f"Retry {attempt + 1}/{max_retries} after {delay:.1f}s")
        time.sleep(delay)

    raise last_exception
```

FILE:python/claude-api/streaming.md
# Streaming — Python

## Quick Start

```python
with client.messages.stream(
    model="claude-opus-4-8",
    max_tokens=64000,
    messages=[{"role": "user", "content": "Write a story"}]
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)
```

### Async

```python
async with async_client.messages.stream(
    model="claude-opus-4-8",
    max_tokens=64000,
    messages=[{"role": "user", "content": "Write a story"}]
) as stream:
    async for text in stream.text_stream:
        print(text, end="", flush=True)
```

### Low-level: `stream=True`

`messages.stream()` (above) is the recommended helper — it accumulates state and exposes `text_stream` / `get_final_message()`. If you only need the raw event iterator and want lower memory use, pass `stream=True` to `messages.create()` instead:

```python
for event in client.messages.create(
    model="claude-opus-4-8",
    max_tokens=64000,
    messages=[{"role": "user", "content": "Write a story"}],
    stream=True,
):
    print(event.type)
```

No final-message accumulation is done for you in this form.

---

## Handling Different Content Types

Claude may return text, thinking blocks, or tool use. Handle each appropriately:

> **Fable 5 / Opus 4.8 / Opus 4.7 / Opus 4.6:** Use `thinking: {type: "adaptive"}`. On older models, use `thinking: {type: "enabled", budget_tokens: N}` instead.

```python
with client.messages.stream(
    model="claude-opus-4-8",
    max_tokens=64000,
    thinking={"type": "adaptive"},
    messages=[{"role": "user", "content": "Analyze this problem"}]
) as stream:
    for event in stream:
        if event.type == "content_block_start":
            if event.content_block.type == "thinking":
                print("\n[Thinking...]")
            elif event.content_block.type == "text":
                print("\n[Response:]")

        elif event.type == "content_block_delta":
            if event.delta.type == "thinking_delta":
                print(event.delta.thinking, end="", flush=True)
            elif event.delta.type == "text_delta":
                print(event.delta.text, end="", flush=True)
```

---

## Streaming with Tool Use

The Python tool runner currently returns complete messages. Use streaming for individual API calls within a manual loop if you need per-token streaming with tools:

```python
with client.messages.stream(
    model="claude-opus-4-8",
    max_tokens=64000,
    tools=tools,
    messages=messages
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)

    response = stream.get_final_message()
    # Continue with tool execution if response.stop_reason == "tool_use"
```

---

## Getting the Final Message

```python
with client.messages.stream(
    model="claude-opus-4-8",
    max_tokens=64000,
    messages=[{"role": "user", "content": "Hello"}]
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)

    # Get full message after streaming
    final_message = stream.get_final_message()
    print(f"\n\nTokens used: {final_message.usage.output_tokens}")
```

---

## Streaming with Progress Updates

```python
def stream_with_progress(client, **kwargs):
    """Stream a response with progress updates."""
    total_tokens = 0
    content_parts = []

    with client.messages.stream(**kwargs) as stream:
        for event in stream:
            if event.type == "content_block_delta":
                if event.delta.type == "text_delta":
                    text = event.delta.text
                    content_parts.append(text)
                    print(text, end="", flush=True)

            elif event.type == "message_delta":
                if event.usage and event.usage.output_tokens is not None:
                    total_tokens = event.usage.output_tokens

        final_message = stream.get_final_message()

    print(f"\n\n[Tokens used: {total_tokens}]")
    return "".join(content_parts)
```

---

## Error Handling in Streams

```python
try:
    with client.messages.stream(
        model="claude-opus-4-8",
        max_tokens=64000,
        messages=[{"role": "user", "content": "Write a story"}]
    ) as stream:
        for text in stream.text_stream:
            print(text, end="", flush=True)
except anthropic.APIConnectionError:
    print("\nConnection lost. Please retry.")
except anthropic.RateLimitError:
    print("\nRate limited. Please wait and retry.")
except anthropic.APIStatusError as e:
    print(f"\nAPI error: {e.status_code}")
```

---

## Stream Event Types

| Event Type            | Description                 | When it fires                     |
| --------------------- | --------------------------- | --------------------------------- |
| `message_start`       | Contains message metadata   | Once at the beginning             |
| `content_block_start` | New content block beginning | When a text/tool_use block starts |
| `content_block_delta` | Incremental content update  | For each token/chunk              |
| `content_block_stop`  | Content block complete      | When a block finishes             |
| `message_delta`       | Message-level updates       | Contains `stop_reason`, usage     |
| `message_stop`        | Message complete            | Once at the end                   |

## Best Practices

1. **Always flush output** — Use `flush=True` to show tokens immediately
2. **Handle partial responses** — If the stream is interrupted, you may have incomplete content
3. **Track token usage** — The `message_delta` event contains usage information
4. **Use timeouts** — Set appropriate timeouts for your application
5. **Default to streaming** — Use `.get_final_message()` to get the complete response even when streaming, giving you timeout protection without needing to handle individual events
6. **Large `max_tokens` without streaming raises `ValueError`** — The SDK refuses non-streaming requests it estimates will exceed ~10 minutes (idle connections drop). Pass `stream=True` / use `messages.stream()`, or explicitly override `timeout`, to suppress the guard.

FILE:python/claude-api/tool-use.md
# Tool Use — Python

For conceptual overview (tool definitions, tool choice, tips), see [shared/tool-use-concepts.md](../../shared/tool-use-concepts.md).

## Tool Runner (Recommended)

**Beta:** The tool runner is in beta in the Python SDK.

Use the `@beta_tool` decorator to define tools as typed functions, then pass them to `client.beta.messages.tool_runner()`:

```python
import anthropic
from anthropic import beta_tool

client = anthropic.Anthropic()

@beta_tool
def get_weather(location: str, unit: str = "celsius") -> str:
    """Get current weather for a location.

    Args:
        location: City and state, e.g., San Francisco, CA.
        unit: Temperature unit, either "celsius" or "fahrenheit".
    """
    # Your implementation here
    return f"72°F and sunny in {location}"

# The tool runner handles the agentic loop automatically
runner = client.beta.messages.tool_runner(
    model="claude-opus-4-8",
    max_tokens=16000,
    tools=[get_weather],
    messages=[{"role": "user", "content": "What's the weather in Paris?"}],
)

# Each iteration yields a BetaMessage; iteration stops when Claude is done
for message in runner:
    print(message)
```

For async usage, use `@beta_async_tool` with `async def` functions.

**Key benefits of the tool runner:**

- No manual loop — the SDK handles calling tools and feeding results back
- Type-safe tool inputs via decorators
- Tool schemas are generated automatically from function signatures
- Iteration stops automatically when Claude has no more tool calls

---

## MCP Tool Conversion Helpers

**Beta.** Convert [MCP (Model Context Protocol)](https://modelcontextprotocol.io/) tools, prompts, and resources to Anthropic API types for use with the tool runner. Requires `pip install anthropic[mcp]` (Python 3.10+).

> **Note:** The Claude API also supports an `mcp_servers` parameter that lets Claude connect directly to remote MCP servers. Use these helpers instead when you need local MCP servers, prompts, resources, or more control over the MCP connection.

### MCP Tools with Tool Runner

```python
from anthropic import AsyncAnthropic
from anthropic.lib.tools.mcp import async_mcp_tool
from mcp import ClientSession
from mcp.client.stdio import stdio_client, StdioServerParameters

client = AsyncAnthropic()

async with stdio_client(StdioServerParameters(command="mcp-server")) as (read, write):
    async with ClientSession(read, write) as mcp_client:
        await mcp_client.initialize()

        tools_result = await mcp_client.list_tools()
        # tool_runner is sync — returns the runner, not a coroutine
        runner = client.beta.messages.tool_runner(
            model="claude-opus-4-8",
            max_tokens=16000,
            messages=[{"role": "user", "content": "Use the available tools"}],
            tools=[async_mcp_tool(t, mcp_client) for t in tools_result.tools],
        )
        async for message in runner:
            print(message)
```

For sync usage, use `mcp_tool` instead of `async_mcp_tool`.

### MCP Prompts

```python
from anthropic.lib.tools.mcp import mcp_message

prompt = await mcp_client.get_prompt(name="my-prompt")
response = await client.beta.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[mcp_message(m) for m in prompt.messages],
)
```

### MCP Resources as Content

```python
from anthropic.lib.tools.mcp import mcp_resource_to_content

resource = await mcp_client.read_resource(uri="file:///path/to/doc.txt")
response = await client.beta.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": [
            mcp_resource_to_content(resource),
            {"type": "text", "text": "Summarize this document"},
        ],
    }],
)
```

### Upload MCP Resources as Files

```python
from anthropic.lib.tools.mcp import mcp_resource_to_file

resource = await mcp_client.read_resource(uri="file:///path/to/data.json")
uploaded = await client.beta.files.upload(file=mcp_resource_to_file(resource))
```

Conversion functions raise `UnsupportedMCPValueError` if an MCP value cannot be converted (e.g., unsupported content types like audio, unsupported MIME types).

---

## Manual Agentic Loop

Use this when you need fine-grained control over the loop (e.g., custom logging, conditional tool execution, human-in-the-loop approval):

```python
import anthropic

client = anthropic.Anthropic()
tools = [...]  # Your tool definitions
messages = [{"role": "user", "content": user_input}]

# Agentic loop: keep going until Claude stops calling tools
while True:
    response = client.messages.create(
        model="claude-opus-4-8",
        max_tokens=16000,
        tools=tools,
        messages=messages
    )

    # If Claude is done (no more tool calls), break
    if response.stop_reason == "end_turn":
        break

    # Server-side tool hit iteration limit; re-send to continue
    if response.stop_reason == "pause_turn":
        messages = [
            {"role": "user", "content": user_input},
            {"role": "assistant", "content": response.content},
        ]
        continue

    # Extract tool use blocks from the response
    tool_use_blocks = [b for b in response.content if b.type == "tool_use"]

    # Append assistant's response (including tool_use blocks)
    messages.append({"role": "assistant", "content": response.content})

    # Execute each tool and collect results
    tool_results = []
    for tool in tool_use_blocks:
        result = execute_tool(tool.name, tool.input)  # Your implementation
        tool_results.append({
            "type": "tool_result",
            "tool_use_id": tool.id,  # Must match the tool_use block's id
            "content": result
        })

    # Append tool results as a user message
    messages.append({"role": "user", "content": tool_results})

# Final response text
final_text = next(b.text for b in response.content if b.type == "text")
```

---

## Handling Tool Results

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    tools=tools,
    messages=[{"role": "user", "content": "What's the weather in Paris?"}]
)

for block in response.content:
    if block.type == "tool_use":
        tool_name = block.name
        tool_input = block.input
        tool_use_id = block.id

        result = execute_tool(tool_name, tool_input)

        followup = client.messages.create(
            model="claude-opus-4-8",
            max_tokens=16000,
            tools=tools,
            messages=[
                {"role": "user", "content": "What's the weather in Paris?"},
                {"role": "assistant", "content": response.content},
                {
                    "role": "user",
                    "content": [{
                        "type": "tool_result",
                        "tool_use_id": tool_use_id,
                        "content": result
                    }]
                }
            ]
        )
```

---

## Multiple Tool Calls

```python
tool_results = []

for block in response.content:
    if block.type == "tool_use":
        result = execute_tool(block.name, block.input)
        tool_results.append({
            "type": "tool_result",
            "tool_use_id": block.id,
            "content": result
        })

# Send all results back at once
if tool_results:
    followup = client.messages.create(
        model="claude-opus-4-8",
        max_tokens=16000,
        tools=tools,
        messages=[
            *previous_messages,
            {"role": "assistant", "content": response.content},
            {"role": "user", "content": tool_results}
        ]
    )
```

---

## Error Handling in Tool Results

```python
tool_result = {
    "type": "tool_result",
    "tool_use_id": tool_use_id,
    "content": "Error: Location 'xyz' not found. Please provide a valid city name.",
    "is_error": True
}
```

---

## Tool Choice

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    tools=tools,
    tool_choice={"type": "tool", "name": "get_weather"},  # Force specific tool
    messages=[{"role": "user", "content": "What's the weather in Paris?"}]
)
```

---

## Code Execution

### Basic Usage

```python
import anthropic

client = anthropic.Anthropic()

response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": "Calculate the mean and standard deviation of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"
    }],
    tools=[{
        "type": "code_execution_20260120",
        "name": "code_execution"
    }]
)

for block in response.content:
    if block.type == "text":
        print(block.text)
    elif block.type == "bash_code_execution_tool_result":
        print(f"stdout: {block.content.stdout}")
```

### Upload Files for Analysis

```python
# 1. Upload a file
uploaded = client.beta.files.upload(file=open("sales_data.csv", "rb"))

# 2. Pass to code execution via container_upload block
# Code execution is GA; Files API is still beta (pass via extra_headers)
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    extra_headers={"anthropic-beta": "files-api-2025-04-14"},
    messages=[{
        "role": "user",
        "content": [
            {"type": "text", "text": "Analyze this sales data. Show trends and create a visualization."},
            {"type": "container_upload", "file_id": uploaded.id}
        ]
    }],
    tools=[{"type": "code_execution_20260120", "name": "code_execution"}]
)
```

### Retrieve Generated Files

```python
import os

OUTPUT_DIR = "./claude_outputs"
os.makedirs(OUTPUT_DIR, exist_ok=True)

for block in response.content:
    if block.type == "bash_code_execution_tool_result":
        result = block.content
        if result.type == "bash_code_execution_result" and result.content:
            for file_ref in result.content:
                if file_ref.type == "bash_code_execution_output":
                    metadata = client.beta.files.retrieve_metadata(file_ref.file_id)
                    file_content = client.beta.files.download(file_ref.file_id)
                    # Use basename to prevent path traversal; validate result
                    safe_name = os.path.basename(metadata.filename)
                    if not safe_name or safe_name in (".", ".."):
                        print(f"Skipping invalid filename: {metadata.filename}")
                        continue
                    output_path = os.path.join(OUTPUT_DIR, safe_name)
                    file_content.write_to_file(output_path)
                    print(f"Saved: {output_path}")
```

### Container Reuse

```python
# First request: set up environment
response1 = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{"role": "user", "content": "Install tabulate and create data.json with sample data"}],
    tools=[{"type": "code_execution_20260120", "name": "code_execution"}]
)

# Get container ID from response
container_id = response1.container.id

# Second request: reuse the same container
response2 = client.messages.create(
    container=container_id,
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{"role": "user", "content": "Read data.json and display as a formatted table"}],
    tools=[{"type": "code_execution_20260120", "name": "code_execution"}]
)
```

### Response Structure

```python
for block in response.content:
    if block.type == "text":
        print(block.text)  # Claude's explanation
    elif block.type == "server_tool_use":
        print(f"Running: {block.name} - {block.input}")  # What Claude is doing
    elif block.type == "bash_code_execution_tool_result":
        result = block.content
        if result.type == "bash_code_execution_result":
            if result.return_code == 0:
                print(f"Output: {result.stdout}")
            else:
                print(f"Error: {result.stderr}")
        else:
            print(f"Tool error: {result.error_code}")
    elif block.type == "text_editor_code_execution_tool_result":
        print(f"File operation: {block.content}")
```

---

## Memory Tool

### Basic Usage

```python
import anthropic

client = anthropic.Anthropic()

response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{"role": "user", "content": "Remember that my preferred language is Python."}],
    tools=[{"type": "memory_20250818", "name": "memory"}],
)
```

### SDK Memory Helper

Subclass `BetaAbstractMemoryTool`:

```python
from anthropic.lib.tools import BetaAbstractMemoryTool

class MyMemoryTool(BetaAbstractMemoryTool):
    def view(self, command): ...
    def create(self, command): ...
    def str_replace(self, command): ...
    def insert(self, command): ...
    def delete(self, command): ...
    def rename(self, command): ...

memory = MyMemoryTool()

# Use with tool runner
runner = client.beta.messages.tool_runner(
    model="claude-opus-4-8",
    max_tokens=16000,
    tools=[memory],
    messages=[{"role": "user", "content": "Remember my preferences"}],
)

for message in runner:
    print(message)
```

For full implementation examples, use WebFetch:

- `https://github.com/anthropics/anthropic-sdk-python/blob/main/examples/memory/basic.py`

---

## Structured Outputs

### JSON Outputs (Pydantic — Recommended)

```python
from pydantic import BaseModel
from typing import List
import anthropic

class ContactInfo(BaseModel):
    name: str
    email: str
    plan: str
    interests: List[str]
    demo_requested: bool

client = anthropic.Anthropic()

response = client.messages.parse(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": "Extract: Jane Doe (jane@co.com) wants Enterprise, interested in API and SDKs, wants a demo."
    }],
    output_format=ContactInfo,
)

# response.parsed_output is a validated ContactInfo instance
contact = response.parsed_output
print(contact.name)           # "Jane Doe"
print(contact.interests)      # ["API", "SDKs"]
```

### Raw Schema

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{
        "role": "user",
        "content": "Extract info: John Smith (john@example.com) wants the Enterprise plan."
    }],
    output_config={
        "format": {
            "type": "json_schema",
            "schema": {
                "type": "object",
                "properties": {
                    "name": {"type": "string"},
                    "email": {"type": "string"},
                    "plan": {"type": "string"},
                    "demo_requested": {"type": "boolean"}
                },
                "required": ["name", "email", "plan", "demo_requested"],
                "additionalProperties": False
            }
        }
    }
)

import json
# output_config.format guarantees the first block is text with valid JSON
text = next(b.text for b in response.content if b.type == "text")
data = json.loads(text)
```

### Strict Tool Use

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{"role": "user", "content": "Book a flight to Tokyo for 2 passengers on March 15"}],
    tools=[{
        "name": "book_flight",
        "description": "Book a flight to a destination",
        "strict": True,
        "input_schema": {
            "type": "object",
            "properties": {
                "destination": {"type": "string"},
                "date": {"type": "string", "format": "date"},
                "passengers": {"type": "integer", "enum": [1, 2, 3, 4, 5, 6, 7, 8]}
            },
            "required": ["destination", "date", "passengers"],
            "additionalProperties": False
        }
    }]
)
```

### Using Both Together

```python
response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=16000,
    messages=[{"role": "user", "content": "Plan a trip to Paris next month"}],
    output_config={
        "format": {
            "type": "json_schema",
            "schema": {
                "type": "object",
                "properties": {
                    "summary": {"type": "string"},
                    "next_steps": {"type": "array", "items": {"type": "string"}}
                },
                "required": ["summary", "next_steps"],
                "additionalProperties": False
            }
        }
    },
    tools=[{
        "name": "search_flights",
        "description": "Search for available flights",
        "strict": True,
        "input_schema": {
            "type": "object",
            "properties": {
                "destination": {"type": "string"},
                "date": {"type": "string", "format": "date"}
            },
            "required": ["destination", "date"],
            "additionalProperties": False
        }
    }]
)
```

FILE:python/managed-agents/README.md
# Managed Agents — Python

> **Bindings not shown here:** This README covers the most common managed-agents flows for Python. If you need a class, method, namespace, field, or behavior that isn't shown, WebFetch the Python SDK repo **or the relevant docs page** from `shared/live-sources.md` rather than guess. Do not extrapolate from cURL shapes or another language's SDK.

> **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `agents.create` and pass it to every subsequent `sessions.create`; do not call `agents.create` in the request path. The Anthropic CLI is one convenient way to create agents and environments from version-controlled YAML — its URL is in `shared/live-sources.md`. The examples below show in-code creation for completeness; in production the create call belongs in setup, not in the request path.

## Installation

```bash
pip install anthropic
```

## Client Initialization

```python
import anthropic

# Default — resolves credentials from the environment:
# ANTHROPIC_API_KEY, or ANTHROPIC_AUTH_TOKEN, or an `ant auth login` profile.
# Prefer this for local dev; don't hardcode a key.
client = anthropic.Anthropic()

# Explicit API key (only when you must inject a specific key)
client = anthropic.Anthropic(api_key="your-api-key")
```

---

## Create an Environment

```python
environment = client.beta.environments.create(
    name="my-dev-env",
    config={
        "type": "cloud",
        "networking": {"type": "unrestricted"},
    },
)
print(environment.id)  # env_...
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** `model`/`system`/`tools` live on the agent object, not the session. Always start with `agents.create()` — the session only takes `agent={"type": "agent", "id": agent.id}`.

### Minimal

```python
# 1. Create the agent (reusable, versioned)
agent = client.beta.agents.create(
    name="Coding Assistant",
    model="claude-opus-4-8",
    tools=[{"type": "agent_toolset_20260401", "default_config": {"enabled": True}}],
)

# 2. Start a session
session = client.beta.sessions.create(
    agent={"type": "agent", "id": agent.id, "version": agent.version},
    environment_id=environment.id,
)
print(session.id, session.status)
```

### With system prompt and custom tools

```python
import os

agent = client.beta.agents.create(
    name="Code Reviewer",
    model="claude-opus-4-8",
    system="You are a senior code reviewer.",
    tools=[
        {"type": "agent_toolset_20260401"},
        {
            "type": "custom",
            "name": "run_tests",
            "description": "Run the test suite",
            "input_schema": {
                "type": "object",
                "properties": {
                    "test_path": {"type": "string", "description": "Path to test file"}
                },
                "required": ["test_path"],
            },
        },
    ],
)

session = client.beta.sessions.create(
    agent={"type": "agent", "id": agent.id, "version": agent.version},
    environment_id=environment.id,
    title="Code review session",
    resources=[
        {
            "type": "github_repository",
            "url": "https://github.com/owner/repo",
            "mount_path": "/workspace/repo",
            "authorization_token": os.environ["GITHUB_TOKEN"],
            "branch": "main",
        }
    ],
)
```

---

## Send a User Message

```python
client.beta.sessions.events.send(
    session_id=session.id,
    events=[
        {
            "type": "user.message",
            "content": [{"type": "text", "text": "Review the auth module"}],
        }
    ],
)
```

> 💡 **Stream-first:** Open the stream *before* (or concurrently with) sending the message. The stream only delivers events that occur after it opens — stream-after-send means early events arrive buffered in one batch. See [Steering Patterns](../../shared/managed-agents-events.md#steering-patterns).

---

## Stream Events (SSE)

```python
import json

# Stream-first: open stream, then send while stream is live
with client.beta.sessions.events.stream(
    session_id=session.id,
) as stream:
    client.beta.sessions.events.send(
        session_id=session.id,
        events=[{"type": "user.message", "content": [{"type": "text", "text": "..."}]}],
    )
    for event in stream:
        ...  # process events

# Standalone stream iteration:
with client.beta.sessions.events.stream(
    session_id=session.id,
) as stream:
    for event in stream:
        if event.type == "agent.message":
            for block in event.content:
                if block.type == "text":
                    print(block.text, end="", flush=True)
        elif event.type == "agent.custom_tool_use":
            # Custom tool invocation — session is now idle
            print(f"\nCustom tool call: {event.name}")
            print(f"Input: {json.dumps(event.input)}")
            # Send result back (see below)
        elif event.type == "session.status_idle":
            print("\n--- Agent idle ---")
        elif event.type == "session.status_terminated":
            print("\n--- Session terminated ---")
            break
```

---

## Provide Custom Tool Result

```python
client.beta.sessions.events.send(
    session_id=session.id,
    events=[
        {
            "type": "user.custom_tool_result",
            "custom_tool_use_id": "sevt_abc123",
            "content": [{"type": "text", "text": "All 42 tests passed."}],
        }
    ],
)
```

---

## Poll Events

```python
events = client.beta.sessions.events.list(
    session_id=session.id,
)
for event in events.data:
    print(f"{event.type}: {event.id}")
```

> ⚠️ **Prefer the SDK over raw `requests`/`httpx`.** If you hand-roll a poll loop, don't assume `timeout=(5, 60)` or `httpx.Timeout(120)` caps total call duration — both are **per-chunk** read timeouts (reset on every byte), so a trickling response can block forever. For a hard wall-clock deadline, track `time.monotonic()` at the loop level and bail explicitly, or wrap with `asyncio.wait_for()`. See [Receiving Events](../../shared/managed-agents-events.md#receiving-events).

---

## Full Streaming Loop with Custom Tools

```python
import json


def run_custom_tool(tool_name: str, tool_input: dict) -> str:
    """Execute a custom tool and return the result."""
    if tool_name == "run_tests":
        # Your tool implementation here
        return "All tests passed."
    return f"Unknown tool: {tool_name}"


def run_session(client, session_id: str):
    """Stream events and handle custom tool calls."""
    while True:
        with client.beta.sessions.events.stream(
            session_id=session_id,
        ) as stream:
            tool_calls = []
            for event in stream:
                if event.type == "agent.message":
                    for block in event.content:
                        if block.type == "text":
                            print(block.text, end="", flush=True)
                elif event.type == "agent.custom_tool_use":
                    tool_calls.append(event)
                elif event.type == "session.status_idle":
                    break
                elif event.type == "session.status_terminated":
                    return

        if not tool_calls:
            break

        # Process custom tool calls
        results = []
        for call in tool_calls:
            result = run_custom_tool(call.name, call.input)
            results.append({
                "type": "user.custom_tool_result",
                "custom_tool_use_id": call.id,
                "content": [{"type": "text", "text": result}],
            })

        client.beta.sessions.events.send(
            session_id=session_id,
            events=results,
        )
```

---

## Upload a File

```python
with open("data.csv", "rb") as f:
    file = client.beta.files.upload(
        file=f,
    )

# Use in a session
session = client.beta.sessions.create(
    agent={"type": "agent", "id": agent.id, "version": agent.version},
    environment_id=environment.id,
    resources=[{"type": "file", "file_id": file.id, "mount_path": "/workspace/data.csv"}],
)
```

---

## List and Download Session Files

List files the agent wrote to `/mnt/session/outputs/` during a session, then download them.

```python
# List files associated with a session
files = client.beta.files.list(
    scope_id=session.id,
    betas=["managed-agents-2026-04-01"],
)
for f in files.data:
    print(f.filename, f.size_bytes)
    # Download each file and save to disk
    file_content = client.beta.files.download(f.id)
    file_content.write_to_file(f.filename)
```

> 💡 There's a brief indexing lag (~1–3s) between `session.status_idle` and output files appearing in `files.list`. Retry once or twice if the list is empty.

---

## Session Management

```python
# Get session details
session = client.beta.sessions.retrieve(session_id="sesn_011CZxAbc123Def456")
print(session.status, session.usage)

# List sessions
sessions = client.beta.sessions.list()

# Delete a session
client.beta.sessions.delete(session_id="sesn_011CZxAbc123Def456")

# Archive a session
client.beta.sessions.archive(session_id="sesn_011CZxAbc123Def456")
```

---

## MCP Server Integration

```python
# Agent declares MCP server (no auth here — auth goes in a vault)
agent = client.beta.agents.create(
    name="MCP Agent",
    model="claude-opus-4-8",
    mcp_servers=[
        {"type": "url", "name": "my-tools", "url": "https://my-mcp-server.example.com/sse"},
    ],
    tools=[
        {"type": "agent_toolset_20260401", "default_config": {"enabled": True}},
        {"type": "mcp_toolset", "mcp_server_name": "my-tools"},
    ],
)

# Session attaches vault(s) containing credentials for those MCP server URLs
session = client.beta.sessions.create(
    agent=agent.id,
    environment_id=environment.id,
    vault_ids=[vault.id],
)
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

FILE:ruby/claude-api.md
# Claude API — Ruby

> **Note:** The Ruby SDK supports the Claude API. A tool runner is available in beta via `client.beta.messages.tool_runner()`. Agent SDK is not yet available for Ruby.

## Installation

```bash
gem install anthropic
```

## Client Initialization

```ruby
require "anthropic"

# Default (uses ANTHROPIC_API_KEY env var)
client = Anthropic::Client.new

# Explicit API key
client = Anthropic::Client.new(api_key: "your-api-key")
```

---

## Basic Message Request

```ruby
message = client.messages.create(
  model: :"claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    { role: "user", content: "What is the capital of France?" }
  ]
)
# content is an array of polymorphic block objects (TextBlock, ThinkingBlock,
# ToolUseBlock, ...). .type is a Symbol — compare with :text, not "text".
# .text raises NoMethodError on non-TextBlock entries.
message.content.each do |block|
  puts block.text if block.type == :text
end
```

---

## Streaming

```ruby
stream = client.messages.stream(
  model: :"claude-opus-4-8",
  max_tokens: 64000,
  messages: [{ role: "user", content: "Write a haiku" }]
)

stream.text.each { |text| print(text) }
```

---

## Tool Use

The Ruby SDK supports tool use via raw JSON schema definitions and also provides a beta tool runner for automatic tool execution.

### Tool Runner (Beta)

```ruby
class GetWeatherInput < Anthropic::BaseModel
  required :location, String, doc: "City and state, e.g. San Francisco, CA"
end

class GetWeather < Anthropic::BaseTool
  doc "Get the current weather for a location"

  input_schema GetWeatherInput

  def call(input)
    "The weather in #{input.location} is sunny and 72°F."
  end
end

client.beta.messages.tool_runner(
  model: :"claude-opus-4-8",
  max_tokens: 16000,
  tools: [GetWeather.new],
  messages: [{ role: "user", content: "What's the weather in San Francisco?" }]
).each_message do |message|
  puts message.content
end
```

### Manual Loop

See the [shared tool use concepts](../shared/tool-use-concepts.md) for the tool definition format and agentic loop pattern.

---

## Prompt Caching

`system_:` (trailing underscore — avoids shadowing `Kernel#system`) takes an array of text blocks; set `cache_control` on the last block. Plain hashes work via the `OrHash` type alias. For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.

```ruby
message = client.messages.create(
  model: :"claude-opus-4-8",
  max_tokens: 16000,
  system_: [
    { type: "text", text: long_system_prompt, cache_control: { type: "ephemeral" } }
  ],
  messages: [{ role: "user", content: "Summarize the key points" }]
)
```

For 1-hour TTL: `cache_control: { type: "ephemeral", ttl: "1h" }`. There's also a top-level `cache_control:` on `messages.create` that auto-places on the last cacheable block.

Verify hits via `message.usage.cache_creation_input_tokens` / `message.usage.cache_read_input_tokens`.

---

## Stop Details

When `stop_reason` is `:refusal`, the response includes structured `stop_details`:

```ruby
if message.stop_reason == :refusal && message.stop_details
  puts "Category: #{message.stop_details.category}"     # :cyber, :bio, or nil
  puts "Explanation: #{message.stop_details.explanation}"
end
```

---

## Error Type

`APIStatusError` exposes a `.type` field for programmatic error classification:

```ruby
begin
  client.messages.create(...)
rescue Anthropic::APIStatusError => e
  puts e.type  # :rate_limit_error, :overloaded_error, etc.
end
```

FILE:ruby/managed-agents/README.md
# Managed Agents — Ruby

> **Bindings not shown here:** This README covers the most common managed-agents flows for Ruby. If you need a class, method, namespace, field, or behavior that isn't shown, WebFetch the Ruby SDK repo **or the relevant docs page** from `shared/live-sources.md` rather than guess. Do not extrapolate from cURL shapes or another language's SDK.

> **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `client.beta.agents.create` and pass it to every subsequent `client.beta.sessions.create`; do not call `agents.create` in the request path. The Anthropic CLI is one convenient way to create agents and environments from version-controlled YAML — its URL is in `shared/live-sources.md`. The examples below show in-code creation for completeness; in production the create call belongs in setup, not in the request path.

## Installation

```bash
gem install anthropic
```

## Client Initialization

```ruby
require "anthropic"

# Default (uses ANTHROPIC_API_KEY env var)
client = Anthropic::Client.new

# Explicit API key
client = Anthropic::Client.new(api_key: "your-api-key")
```

> ⚠️ **Trailing underscores:** The Ruby SDK uses `system_:` and `send_(` (trailing underscore) to avoid shadowing `Kernel#system` and `Kernel#send`. Use these forms throughout managed-agents code.

---

## Create an Environment

```ruby
environment = client.beta.environments.create(
  name: "my-dev-env",
  config: {
    type: "cloud",
    networking: {type: "unrestricted"}
  }
)
puts "Environment ID: #{environment.id}" # env_...
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** `model`/`system_`/`tools` live on the agent object, not the session. Always start with `client.beta.agents.create()` — the session takes either `agent: agent.id` or the typed hash form `agent: {type: "agent", id: agent.id, version: agent.version}`.

### Minimal

```ruby
# 1. Create the agent (reusable, versioned)
agent = client.beta.agents.create(
  name: "Coding Assistant",
  model: :"claude-opus-4-8",
  system_: "You are a helpful coding assistant.",
  tools: [{type: "agent_toolset_20260401"}]
)

# 2. Start a session
session = client.beta.sessions.create(
  agent: {type: "agent", id: agent.id, version: agent.version},
  environment_id: environment.id,
  title: "Quickstart session"
)
puts "Session ID: #{session.id}"
```

### Updating an Agent

Updates create new versions; the agent object is immutable per version.

```ruby
updated_agent = client.beta.agents.update(
  agent.id,
  version: agent.version,
  system_: "You are a helpful coding agent. Always write tests."
)
puts "New version: #{updated_agent.version}"

# List all versions
client.beta.agents.versions.list(agent.id).auto_paging_each do |version|
  puts "Version #{version.version}: #{version.updated_at.iso8601}"
end

# Archive the agent
archived = client.beta.agents.archive(agent.id)
puts "Archived at: #{archived.archived_at.iso8601}"
```

---

## Send a User Message

```ruby
client.beta.sessions.events.send_(
  session.id,
  events: [{
    type: "user.message",
    content: [{type: "text", text: "Review the auth module"}]
  }]
)
```

> 💡 **Stream-first:** Open the stream *before* (or concurrently with) sending the message. The stream only delivers events that occur after it opens — stream-after-send means early events arrive buffered in one batch. See [Steering Patterns](../../shared/managed-agents-events.md#steering-patterns).

---

## Stream Events (SSE)

```ruby
# Open the stream first, then send the user message
stream = client.beta.sessions.events.stream_events(session.id)

client.beta.sessions.events.send_(
  session.id,
  events: [{
    type: "user.message",
    content: [{type: "text", text: "Summarize the repo README"}]
  }]
)

stream.each do |event|
  case event.type
  in :"agent.message"
    event.content.each { |block| print block.text }
  in :"agent.tool_use"
    puts "\n[Using tool: #{event.name}]"
  in :"session.status_idle"
    break
  in :"session.error"
    puts "\n[Error: #{event.error&.message || "unknown"}]"
    break
  else
    # ignore other event types
  end
end
```

> ℹ️ Event `.type` is a Symbol (compare with `:"agent.message"`, not `"agent.message"`).

### Reconnecting and Tailing

When reconnecting mid-session, list past events first to dedupe, then tail live events:

```ruby
require "set"

stream = client.beta.sessions.events.stream_events(session.id)

# Stream is open and buffering. List history before tailing live.
seen_event_ids = Set.new
client.beta.sessions.events.list(session.id).auto_paging_each { |past| seen_event_ids << past.id }

# Tail live events, skipping anything already seen
stream.each do |event|
  next if seen_event_ids.include?(event.id)
  seen_event_ids << event.id
  case event.type
  in :"agent.message"
    event.content.each { |block| print block.text }
  in :"session.status_idle"
    break
  else
    # ignore other event types
  end
end
```

---

## Provide Custom Tool Result

> ℹ️ The Ruby managed-agents bindings for `user.custom_tool_result` are not yet documented in this skill or in the apps source examples. Refer to `shared/managed-agents-events.md` for the wire format and the `anthropic` Ruby gem repository for the corresponding params.

---

## Poll Events

```ruby
client.beta.sessions.events.list(session.id).auto_paging_each do |event|
  puts "#{event.type}: #{event.id}"
end
```

---

## Upload a File

```ruby
require "pathname"

file = client.beta.files.upload(file: Pathname("data.csv"))
puts "File ID: #{file.id}"

# Mount in a session
session = client.beta.sessions.create(
  agent: agent.id,
  environment_id: environment.id,
  resources: [
    {
      type: "file",
      file_id: file.id,
      mount_path: "/workspace/data.csv"
    }
  ]
)
```

### Add and Manage Resources on an Existing Session

```ruby
# Attach an additional file to an open session
resource = client.beta.sessions.resources.add(
  session.id,
  type: "file",
  file_id: file.id
)
puts resource.id # "sesrsc_01ABC..."

# List resources on the session
listed = client.beta.sessions.resources.list(session.id)
listed.data.each { |entry| puts "#{entry.id} #{entry.type}" }

# Detach a resource
client.beta.sessions.resources.delete(resource.id, session_id: session.id)
```

---

## List and Download Session Files

> ℹ️ Listing and downloading files an agent wrote during a session is not yet documented for Ruby in this skill or in the apps source examples. See `shared/managed-agents-events.md` and the `anthropic` Ruby gem repository for the file list/download bindings.

---

## Session Management

```ruby
# List environments
environments = client.beta.environments.list

# Retrieve a specific environment
env = client.beta.environments.retrieve(environment.id)

# Archive an environment (read-only, existing sessions continue)
client.beta.environments.archive(environment.id)

# Delete an environment (only if no sessions reference it)
client.beta.environments.delete(environment.id)

# Delete a session
client.beta.sessions.delete(session.id)
```

---

## MCP Server Integration

```ruby
# Agent declares MCP server (no auth here — auth goes in a vault)
agent = client.beta.agents.create(
  name: "GitHub Assistant",
  model: :"claude-opus-4-8",
  mcp_servers: [
    {
      type: "url",
      name: "github",
      url: "https://api.githubcopilot.com/mcp/"
    }
  ],
  tools: [
    {type: "agent_toolset_20260401"},
    {type: "mcp_toolset", mcp_server_name: "github"}
  ]
)

# Session attaches vault(s) containing credentials for those MCP server URLs
session = client.beta.sessions.create(
  agent: {type: "agent", id: agent.id, version: agent.version},
  environment_id: environment.id,
  vault_ids: [vault.id]
)
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

---

## Vaults

```ruby
# Create a vault
vault = client.beta.vaults.create(
  display_name: "Alice",
  metadata: {external_user_id: "usr_abc123"}
)
puts vault.id # "vlt_01ABC..."

# Add an OAuth credential
credential = client.beta.vaults.credentials.create(
  vault.id,
  display_name: "Alice's Slack",
  auth: {
    type: "mcp_oauth",
    mcp_server_url: "https://mcp.slack.com/mcp",
    access_token: "xoxp-...",
    expires_at: "2026-04-15T00:00:00Z",
    refresh: {
      token_endpoint: "https://slack.com/api/oauth.v2.access",
      client_id: "1234567890.0987654321",
      scope: "channels:read chat:write",
      refresh_token: "xoxe-1-...",
      token_endpoint_auth: {
        type: "client_secret_post",
        client_secret: "abc123..."
      }
    }
  }
)

# Rotate the credential (e.g., after a token refresh)
client.beta.vaults.credentials.update(
  credential.id,
  vault_id: vault.id,
  auth: {
    type: "mcp_oauth",
    access_token: "xoxp-new-...",
    expires_at: "2026-05-15T00:00:00Z",
    refresh: {refresh_token: "xoxe-1-new-..."}
  }
)

# Archive a vault
client.beta.vaults.archive(vault.id)
```

---

## GitHub Repository Integration

Mount a GitHub repository as a session resource (a vault holds the GitHub MCP credential):

```ruby
session = client.beta.sessions.create(
  agent: agent.id,
  environment_id: environment.id,
  vault_ids: [vault.id],
  resources: [
    {
      type: "github_repository",
      url: "https://github.com/org/repo",
      mount_path: "/workspace/repo",
      authorization_token: "ghp_your_github_token"
    }
  ]
)
```

Multiple repositories on the same session:

```ruby
resources = [
  {
    type: "github_repository",
    url: "https://github.com/org/frontend",
    mount_path: "/workspace/frontend",
    authorization_token: "ghp_your_github_token"
  },
  {
    type: "github_repository",
    url: "https://github.com/org/backend",
    mount_path: "/workspace/backend",
    authorization_token: "ghp_your_github_token"
  }
]
```

Rotating a repository's authorization token:

```ruby
listed = client.beta.sessions.resources.list(session.id)
repo_resource_id = listed.data.first.id

client.beta.sessions.resources.update(
  repo_resource_id,
  session_id: session.id,
  authorization_token: "ghp_your_new_github_token"
)
```

FILE:shared/agent-design.md
# Agent Design Patterns

This file covers decision heuristics for building agents on the Claude API: which primitives to reach for, how to design your tool surface, and how to manage context and cost over long runs. For per-tool mechanics and code examples, see `tool-use-concepts.md` and the language-specific folders.

---

## Model Parameters

| Parameter | When to use it | What to expect |
| --- | --- | --- |
| **Adaptive thinking** (`thinking: {type: "adaptive"}`) | When you want Claude to control when and how much to think. | Claude determines thinking depth per request and automatically interleaves thinking between tool calls. No token budget to tune. |
| **Effort** (`output_config: {effort: ...}`) | When adjusting the tradeoff between thoroughness and token efficiency. | Lower effort → fewer and more-consolidated tool calls, less preamble, terser confirmations. `medium` is often a favorable balance. Use `max` when correctness matters more than cost. |

See `SKILL.md` §Thinking & Effort for model support and parameter details.

---

## Designing Your Tool Surface

### Bash vs. dedicated tools

Claude doesn't know your application's security boundary, approval policy, or UX surface. Claude emits tool calls; your harness handles them. The shape of those tool calls determines what the harness can do.

A **bash tool** gives Claude broad programmatic leverage — it can perform almost any action. But it gives the harness only an opaque command string, the same shape for every action. Promoting an action to a **dedicated tool** gives the harness an action-specific hook with typed arguments it can intercept, gate, render, or audit.

**When to promote an action to a dedicated tool:**

- **Security boundary.** Actions that require gating are natural candidates. Reversibility is a useful criterion: hard-to-reverse actions (external API calls, sending messages, deleting data) can be gated behind user confirmation. A `send_email` tool is easy to gate; `bash -c "curl -X POST ..."` is not.
- **Staleness checks.** A dedicated `edit` tool can reject writes if the file changed since Claude last read it. Bash can't enforce that invariant.
- **Rendering.** Some actions benefit from custom UI. Claude Code promotes question-asking to a tool so it can render as a modal, present options, and block the agent loop until answered.
- **Scheduling.** Read-only tools like `glob` and `grep` can be marked parallel-safe. When the same actions run through bash, the harness can't tell a parallel-safe `grep` from a parallel-unsafe `git push`, so it must serialize.

**Rule of thumb:** Start with bash for breadth. Promote to dedicated tools when you need to gate, render, audit, or parallelize the action.

---

## Anthropic-Provided Tools

| Tool | Side | When to use it | What to expect |
| --- | --- | --- | --- |
| **Bash** | Client | Claude needs to execute shell commands. | Claude emits commands; your harness executes them. Reference implementation provided. |
| **Text editor** | Client | Claude needs to read or edit files. | Claude views, creates, and edits files via your implementation. Reference implementation provided. |
| **Computer use** | Client or Server | Claude needs to interact with GUIs, web apps, or visual interfaces. | Claude takes screenshots and issues mouse/keyboard commands. Can be self-hosted (you run the environment) or Anthropic-hosted. |
| **Code execution** | Server | Claude needs to run code in a sandbox you don't want to manage. | Anthropic-hosted container with built-in file and bash sub-tools. No client-side execution. |
| **Web search / fetch** | Server | Claude needs information past its training cutoff (news, current events, recent docs) or the content of a specific URL. | Claude issues a query or URL; Anthropic executes it and returns results with citations. |
| **Memory** | Client | Claude needs to save context across sessions. | Claude reads/writes a `/memories` directory. You implement the storage backend. |

**Client-side** tools are defined by Anthropic (name, schema, Claude's usage pattern) but executed by your harness. Anthropic provides reference implementations. **Server-side** tools run entirely on Anthropic infrastructure — declare them in `tools` and Claude handles the rest.

---

## Composing Tool Calls: Programmatic Tool Calling

With standard tool use, each tool call is a round trip: Claude calls the tool, the result lands in Claude's context, Claude reasons about it, then calls the next tool. Three sequential actions (read profile → look up orders → check inventory) means three round trips. Each adds latency and tokens, and most of the intermediate data is never needed again.

**Programmatic tool calling (PTC)** lets Claude compose those calls into a script instead. The script runs in the code execution container. When the script calls a tool, the container pauses, the call is executed (client-side or server-side), and the result returns to the running code — not to Claude's context. The script processes it with normal control flow (loops, filters, branches). Only the script's final output returns to Claude.

| When to use it | What to expect |
| --- | --- |
| Many sequential tool calls, or large intermediate results you want filtered before they hit the context window. | Claude writes code that invokes tools as functions. Runs in the code execution container. Token cost scales with final output, not intermediate results. |

---

## Scaling the Tool and Instruction Set

| Feature | When to use it | What to expect |
| --- | --- | --- |
| **Tool search** | Many tools available, but only a few relevant per request. Don't want all schemas in context upfront. | Claude searches the tool set and loads only relevant schemas. Tool definitions are appended, not swapped — preserves cache (see Caching below). |
| **Skills** | Task-specific instructions Claude should load only when relevant. | Each skill is a folder with a `SKILL.md`. The skill's description sits in context by default; Claude reads the full file when the task calls for it. |

Both patterns keep the fixed context small and load detail on demand.

---

## Long-Running Agents: Managing Context

| Pattern | When to use it | What to expect |
| --- | --- | --- |
| **Context editing** | Context grows stale over many turns (old tool results, completed thinking). | Tool results and thinking blocks are cleared based on configurable thresholds. Keeps the transcript lean without summarizing. |
| **Compaction** | Conversation likely to reach or exceed the context window limit. | Earlier context is summarized into a compaction block server-side. See `SKILL.md` §Compaction for the critical `response.content` handling. |
| **Memory** | State must persist across sessions (not just within one conversation). | Claude reads/writes files in a memory directory. Survives process restarts. |

**Choosing between them:** Context editing and compaction operate within a session — editing prunes stale turns, compaction summarizes when you're near the limit. Memory is for cross-session persistence. Many long-running agents use all three.

---

## Caching for Agents

**Read `prompt-caching.md` first.** It covers the prefix-match invariant, breakpoint placement, the silent-invalidator audit, and why changing tools or models mid-session breaks the cache. This section covers only the agent-specific workarounds for those constraints.

| Constraint (from `prompt-caching.md`) | Agent-specific workaround |
| --- | --- |
| Editing the system prompt mid-session invalidates the cache. | Append a `{"role": "system", ...}` message to `messages[]` instead (beta, on supporting models — see `prompt-caching.md` § Mid-conversation system messages). The cached prefix stays intact, and the model treats it as an operator-authority instruction rather than user text. On models that don't support it, fall back to a `<system-reminder>` text block in the user turn. |
| Switching models mid-session invalidates the cache. | Spawn a **subagent** with the cheaper model for the sub-task; keep the main loop on one model. Claude Code's Explore subagents use Haiku this way. |
| Adding/removing tools mid-session invalidates the cache. | Use **tool search** for dynamic discovery — it appends tool schemas rather than swapping them, so the existing prefix is preserved. |

For multi-turn breakpoint placement, use top-level auto-caching — see `prompt-caching.md` §Placement patterns.

---

For live documentation on any of these features, see `live-sources.md`.

FILE:shared/anthropic-cli.md
# Anthropic CLI (`ant`)

The `ant` CLI exposes every Claude API resource as a shell subcommand. Compared to `curl`: request bodies are built from typed flags or piped YAML instead of hand-written JSON, `@path` inlines file contents into any string field, `--transform` extracts fields with a GJSON path (no `jq`), list endpoints auto-paginate (cap total results with `--max-items N`; `--limit` only sets the server page size), and the `beta:` prefix auto-sets the right `anthropic-beta` header.

## When to use the CLI vs the SDK

**CLI for the control plane, SDK for the data plane.** Agents and environments are relatively static resources you define, configure, and debug with `ant` — check the YAML into your repo, apply from CI, inspect from a terminal. Sessions are dynamic and driven by your application through the SDK — create per task, stream events, react to tool calls, integrate into your product. Both hit the same API; the split is about where the call lives, not what's possible.

| | Control plane → `ant` | Data plane → SDK |
|---|---|---|
| Resources | agents, environments, skills, vaults, files | sessions, events |
| Cadence | Once per deploy / ad-hoc | Every task / every turn |
| Lives in | `*.yaml` in your repo + CI + terminal | Application code |
| Typical calls | `create < agent.yaml`, `update --version N`, `list`, `retrieve`, `archive`, `--debug` | `sessions.create()`, `events.stream()`, `events.send()` |

## Install and auth

```sh
# macOS
brew install anthropics/tap/ant
xattr -d com.apple.quarantine "$(brew --prefix)/bin/ant"

# Linux / WSL — pick the release from github.com/anthropics/anthropic-cli/releases
curl -fsSL "https://github.com/anthropics/anthropic-cli/releases/download/vVERSION/ant_VERSION_$(uname -s | tr A-Z a-z)_$(uname -m | sed -e s/x86_64/amd64/ -e s/aarch64/arm64/).tar.gz" \
  | sudo tar -xz -C /usr/local/bin ant

# Or from source (Go 1.22+)
go install github.com/anthropics/anthropic-cli/cmd/ant@latest
```

**Auth** — the CLI resolves credentials the same way the SDKs do (first match wins): explicit flags, then `ANTHROPIC_API_KEY`, then `ANTHROPIC_AUTH_TOKEN`, then the `ANTHROPIC_PROFILE`-selected or active profile, then Workload Identity Federation env vars, then the default profile on disk. Override the host with `ANTHROPIC_BASE_URL` or `--base-url`.

- **API key**: set `ANTHROPIC_API_KEY` in the environment.
- **OAuth profile** (no static key to manage): `ant auth login` opens a browser, exchanges for a short-lived token, and stores a profile under `$ANTHROPIC_CONFIG_DIR` (default `~/.config/anthropic/` on Linux/macOS, `%APPDATA%\Anthropic` on Windows — `configs/<profile>.json` for settings, `credentials/<profile>.json` for tokens). Subsequent `ant` (and SDK) calls pick it up automatically — a bare `Anthropic()` client works after login, but scripts that read `ANTHROPIC_API_KEY` directly do not. Claude Code and the Claude Agent SDK honor the same profile resolution. `ant auth status` shows which credential source and profile won (it reports status only — don't script against its exit code as a health check); `ant auth logout` clears the active profile (`--all` for every profile). On a remote host without a browser, `ant auth login --no-browser` prints the authorize URL and accepts the code back in the terminal.
- **Non-interactive workloads** (CI, servers, containers): interactive login is for development on your own machine — use Workload Identity Federation instead (see the authentication docs via `shared/live-sources.md`).

> **The #1 auth trap:** profiles are only consulted when no API key is set. A stale exported `ANTHROPIC_API_KEY` silently overrides every profile — requests hit whatever org/workspace that key is scoped to. `ant auth status` shows which source won; unset the key (or per-command: `env -u ANTHROPIC_API_KEY ant …`) before relying on a profile. Truly **unset** it — an empty `ANTHROPIC_API_KEY=""` still wins its precedence slot and authenticates with an empty key. The same shadowing applies in reverse to Claude Code: after `ant auth login`, Claude Code may warn about an auth conflict between the profile and its own `/login` credential — keep one (use the profile and `/logout` in Claude Code, or `ant auth logout` to keep Claude Code's own login).

**Named profiles** — an interactive-login token is bound to a single org+workspace, and the API only shows resources belonging to that workspace. If an agent, session, or file you created "disappears", the usual cause is a token scoped to a different workspace than the one that created it (`ant auth status` shows the active workspace). Multi-workspace work means one profile per workspace:

```sh
ant auth login --profile <name>                  # creates the profile if it doesn't exist; org/workspace picker in browser
ant auth login --profile <name> --workspace-id wrkspc_01...   # bind directly, skip the picker
ant profile activate <name>                      # switch the default profile
ant --profile <name> models list                 # one-off; equivalent: ANTHROPIC_PROFILE=<name> ant models list
ant profile list                                 # inspect
ant profile set workspace_id wrkspc_01... --profile <name>    # edit config keys (workspace_id, base_url, organization_id, …)
```

`ant profile set` edits an existing profile's config — it never creates one, and it does **not** rebind already-issued credentials; run `ant auth login` again under that profile to mint a token for the new target. Pointing `ANTHROPIC_PROFILE` at a profile that doesn't exist is an error, not a fall-through. Refresh tokens eventually hard-expire (they don't slide with use) — when a previously working profile starts failing auth, re-run `ant auth login` before debugging anything else.

**Scopes** — a profile's OAuth scope set is requested at login (`--scope`) and persists on the profile (`scope` is also a `profile set` config key; like other config edits, changing it requires a fresh `ant auth login` to take effect). Privileged scopes — e.g. `org:admin` for organization-administration endpoints — are **not** in the default scope set: pass the full set you want explicitly (`ant auth login --profile admin --scope "... org:admin"`), and the server grants a privileged scope only if your role actually has it. Because the scope set rides on every token the profile mints, keep privileged work on a dedicated profile (`admin` vs `default`) and do day-to-day inference on the unprivileged one, switching with `--profile`/`ANTHROPIC_PROFILE`. Check `ant auth login --help` for the current scope list, and `ant auth status` to see what the active token carries.

To hand the active credential to a subprocess or raw-HTTP script:

```sh
# Bare access token — for curl's Authorization header
curl https://api.anthropic.com/v1/messages \
  -H "Authorization: Bearer $(ant auth print-credentials --access-token)" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: oauth-2025-04-20" \
  -H "content-type: application/json" \
  -d '{"model": "claude-opus-4-8", "max_tokens": 1024, "messages": [{"role": "user", "content": "Hello"}]}'

# .env format — sets ANTHROPIC_AUTH_TOKEN (and ANTHROPIC_BASE_URL if the profile has one).
# Output is bare KEY=value (no `export`), so use `set -a` to auto-export for child processes:
set -a; eval "$(ant auth print-credentials --env)"; set +a
python my_script.py   # SDK picks up ANTHROPIC_AUTH_TOKEN
```

OAuth tokens go on `Authorization: Bearer` (not `x-api-key:`) **plus the `anthropic-beta: oauth-2025-04-20` header** — converting a raw curl/httpx script from an API key is a header change, not a key swap. The beta header requirement is endpoint-dependent (some endpoints happen to work without it; `/v1/messages` does not) — always send it so requests don't break when you switch endpoints. The token is short-lived and not auto-refreshed when passed via env var, so re-run `print-credentials` before it expires for long-running scripts (`print-credentials` itself refreshes the token if needed). If both `ANTHROPIC_API_KEY` and `ANTHROPIC_AUTH_TOKEN` are set, the SDKs send both and the API rejects the request — unset `ANTHROPIC_API_KEY` before `eval`ing the `--env` output.

**Foot-gun:** `ant auth print-credentials` with **no flags** prints the entire credentials JSON, not the bare token — putting that in an `Authorization` header yields an empty response or HTTP/2 protocol error. Always use `--access-token` for headers (it always reads the named/active profile; a set `ANTHROPIC_API_KEY` doesn't override credential printing).

## Command structure

```
ant <resource>[:<subresource>] <action> [flags]
```

Beta resources (agents, sessions, environments, deployments, skills, vaults, memory stores) live under `beta:` — the CLI auto-sends the right `anthropic-beta` header, so don't pass it yourself unless overriding with `--beta <header>`. For self-hosted environments, `ant beta:worker poll/run` and `ant beta:environments:work stats/stop` drive and monitor the work queue — see `shared/managed-agents-self-hosted-sandboxes.md`.

```sh
ant models list
ant messages create --model claude-opus-4-8 --max-tokens 1024 --message '{role: user, content: "Hello"}'
ant beta:agents retrieve --agent-id agent_01...
ant beta:sessions:events list --session-id session_01...
```

`ant --help` lists resources; append `--help` to any subcommand for its flags.

## Global flags

| Flag | Purpose |
| --- | --- |
| `--format` | `auto` (default: pretty if TTY, compact if piped), `json`, `jsonl`, `yaml`, `pretty`, `raw`, `explore` (interactive TUI) |
| `--transform` | GJSON path applied to the response (per-item on list endpoints). Not applied when `--format raw`. |
| `-r`, `--raw-output` | If the transformed result is a string, print it without quotes (jq semantics). Pair with `--transform` for scalar capture. |
| `--max-items` | Cap total results returned from auto-paginating list endpoints (distinct from `--limit`, which is the server page size). |
| `--format-error` / `--transform-error` | Same as `--format`/`--transform`, applied to error responses. `-r` does not apply to the error path — use `--format-error yaml` for unquoted error scalars. |
| `--base-url` | Override API host |
| `--debug` | Print full HTTP request + response to stderr (API key redacted) |

## Output — `--transform` + `--format`

`--transform` takes a [GJSON path](https://github.com/tidwall/gjson/blob/master/SYNTAX.md). On list endpoints it runs **per item**, not on the envelope.

```sh
ant beta:agents list --transform '{id,name,model}' --format jsonl
```

**Extract a scalar for shell use:** pair `--transform` with `-r` (`--raw-output` — prints strings unquoted, jq-style):

```sh
AGENT_ID=$(ant beta:agents create --name "My Agent" --model '{id: claude-sonnet-4-6}' \
  --transform id -r)
```

## Input — flags, stdin, `@file`

**Flags** — scalar fields map directly. Structured fields accept relaxed-YAML syntax (unquoted keys) or strict JSON. Repeatable flags build arrays (each `--tool`, `--event`, `--message` appends one element):

```sh
ant beta:agents create \
  --name "Research Agent" \
  --model '{id: claude-opus-4-8}' \
  --tool '{type: agent_toolset_20260401}' \
  --tool '{type: custom, name: search_docs, input_schema: {type: object, properties: {query: {type: string}}}}'
```

**Stdin** — pipe a full JSON or YAML body. Merged with flags; flags win on conflict (for array fields, any flag **replaces** the stdin array entirely — it does not append). Quote the heredoc delimiter (`<<'YAML'`) to disable shell expansion inside the body:

```sh
ant beta:agents create <<'YAML'
name: Research Agent
model: claude-opus-4-8
system: |
  You are a research assistant. Cite sources for every claim.
tools:
  - type: agent_toolset_20260401
YAML
```

**`@file` references** — inline a file's contents into any string-valued field. Inside structured flag values, quote the path. Binary files are auto-base64'd; force with `@file://` (text) or `@data://` (base64). Escape a literal leading `@` as `\@`.

```sh
ant beta:agents create --name "Researcher" --model '{id: claude-sonnet-4-6}' --system @./prompts/researcher.txt

ant messages create --model claude-opus-4-8 --max-tokens 1024 \
  --message '{role: user, content: [
    {type: document, source: {type: base64, media_type: application/pdf, data: "@./scan.pdf"}},
    {type: text, text: "Extract the text from this scanned document."}
  ]}' \
  --transform 'content.0.text' -r
```

Flags that natively take a file path (e.g. `--file` on `beta:files upload`) accept a bare path without `@`.

## Version-controlled Managed Agents resources

This is the recommended flow for defining agents and environments — check the YAML into your repo and sync via `create` (first time) / `update` (thereafter). See `shared/managed-agents-core.md` for the field reference.

```yaml
# summarizer.agent.yaml
name: Summarizer
model: claude-sonnet-4-6
system: |
  You are a helpful assistant that writes concise summaries.
tools:
  - type: agent_toolset_20260401
```

```sh
# Create (once) — capture the ID
AGENT_ID=$(ant beta:agents create < summarizer.agent.yaml --transform id -r)

# Update (CI) — needs ID + current version (optimistic lock)
ant beta:agents update --agent-id "$AGENT_ID" --version 1 < summarizer.agent.yaml
```

Same pattern for environments (`ant beta:environments create|update < env.yaml`), then start a session with both IDs:

```sh
ant beta:sessions create --agent "$AGENT_ID" --environment-id "$ENV_ID" --title "Task"
ant beta:sessions:events send --session-id "$SID" \
  --event '{type: user.message, content: [{type: text, text: "Summarize X"}]}'
ant beta:sessions:events list --session-id "$SID" --transform 'content.0.text' -r
ant beta:sessions:events stream --session-id "$SID"   # live event stream
```

### Interactive session loop (stream-before-send)

`ant beta:sessions:events stream` only delivers events emitted *after* the stream opens — so open it **before** sending the kickoff to avoid missing early events. Use process substitution to hold the stream on a file descriptor, send, then read:

```sh
exec {stream}< <(ant beta:sessions:events stream --session-id "$SID" \
  --transform '{type,text:content.#(type=="text").text,err:error.message}' --format yaml)

ant beta:sessions:events send --session-id "$SID" > /dev/null <<'YAML'
events:
  - type: user.message
    content:
      - type: text
        text: Summarize the repo README
YAML

type=
while IFS= read -r -u "$stream" line; do
  case "$line" in
    type:\ session.status_idle) break ;;
    type:\ session.error)
      IFS= read -r -u "$stream" next || next=
      case "$next" in err:\ *) msg=next#err ;; *) msg=unknown ;; esac
      printf '\n[Error: %s]\n' "$msg"; break ;;
    type:\ *) type=line#type ;;
    text:*)
      [[ $type == agent.message ]] || continue
      val=line#text
      case "$val" in '|-'|'|') ;; *) printf '%s' "$val" ;; esac ;;
    \ \ *)
      if [[ $type == agent.message ]]; then printf '%s\n' "line#"; fi ;;
  esac
done
exec {stream}<&-
```

This works for interactive exploration and demos. For application code that needs to react to `agent.tool_use` / `agent.custom_tool_use` events, reconnect after drops, or dedup against `events.list`, use the SDK — see `shared/managed-agents-client-patterns.md`.

## Scripting patterns

`--transform id -r` on a list endpoint emits one bare ID per line — compose with `xargs`, or use `--max-items N` to bound the result set without piping through `head`:

```sh
FIRST=$(ant beta:agents list --transform id -r --max-items 1)
ant beta:agents:versions list --agent-id "$FIRST" --transform '{version,created_at}' --format jsonl
```

Error shaping mirrors the success path (note: `-r` does not apply to error output — use `--format-error yaml` for an unquoted scalar here):

```sh
ant beta:agents retrieve --agent-id bogus --transform-error error.message --format-error yaml 2>&1
```

Shell completion: `ant @completion {zsh|bash|fish|powershell}`.

For the full, always-current reference (including per-endpoint flags), WebFetch the **Anthropic CLI** URL in `shared/live-sources.md`.

FILE:shared/claude-platform-on-aws.md
# Claude Platform on AWS

**Anthropic-operated** access to the Claude Developer Platform through AWS infrastructure — SigV4 authentication, AWS IAM access control, and AWS Marketplace billing. Because Anthropic operates it, **the API surface matches first-party with same-day parity**: Managed Agents, server-side tools, batches, Files, and every feature in this skill work the same way (**except self-hosted sandboxes** — `config:{type:"self_hosted"}` is not available here; use `cloud`). Model IDs are the bare first-party strings (`claude-opus-4-8`, `claude-sonnet-4-6`) — **no provider prefix**.

> **Not the same as Amazon Bedrock.** Bedrock is partner-operated (AWS runs the service; release schedules vary, feature subset, `anthropic.`-prefixed model IDs). Claude Platform on AWS and Bedrock coexist; pick by whether you need AWS-native IAM/billing with full Anthropic API parity (this page) vs. Bedrock's own ecosystem.

---

## Client & install

| Language | Install | Client |
|---|---|---|
| Python | `pip install -U "anthropic[aws]"` | `from anthropic import AnthropicAWS` → `AnthropicAWS()` |
| TypeScript | `npm install @anthropic-ai/aws-sdk` | `import AnthropicAws from "@anthropic-ai/aws-sdk"` → `new AnthropicAws()` |
| Go | `go get github.com/anthropics/anthropic-sdk-go` | `import anthropicaws "github.com/anthropics/anthropic-sdk-go/aws"` → `anthropicaws.NewClient(ctx, anthropicaws.ClientConfig{})` |
| C# | `dotnet add package Anthropic.Aws` | `new AnthropicAwsClient()` |
| Java | See SDK repo in `shared/live-sources.md` | See SDK repo in `shared/live-sources.md` |
| Ruby | `gem install anthropic aws-sdk-core` | See SDK repo in `shared/live-sources.md` |
| PHP | `composer require anthropic-ai/sdk aws/aws-sdk-php` | See SDK repo in `shared/live-sources.md` |

After construction, **use the client exactly as you would `Anthropic()`** — `client.messages.create(...)`, `client.beta.sessions.*`, etc., with bare model IDs.

```python
from anthropic import AnthropicAWS

client = AnthropicAWS()  # region + workspace_id from env; see below
client.messages.create(
    model="claude-opus-4-8",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}],
)
```

---

## Required configuration

Two values must be available (constructor args or environment) — **there is no default fallback** for either:

| Value | Env var | Notes |
|---|---|---|
| AWS region | `AWS_REGION` | Required. Unlike `AnthropicBedrock`, there is no `us-east-1` fallback. |
| Workspace ID | `ANTHROPIC_AWS_WORKSPACE_ID` | Required. Routes requests to your Claude workspace. |

Endpoint pattern: `https://aws-external-anthropic.{region}.api.aws/v1/...`. Requests are SigV4-signed with service name `aws-external-anthropic`.

## Authentication

The client resolves AWS credentials via the standard precedence chain: explicit constructor args → environment (`AWS_ACCESS_KEY_ID`/`AWS_SECRET_ACCESS_KEY`/`AWS_SESSION_TOKEN`) → shared profile → assumed role / instance metadata.

**Short-term API keys** are also supported for cases where SigV4 isn't practical (e.g., browser, simple scripts). Mint one with the per-language token-generator package; pass it as `api_key` on the client. Lifetime is the **lesser of** the requested duration, the underlying credential's expiry, and **12 hours**. For package names and IAM details, WebFetch the Claude Platform on AWS page in `shared/live-sources.md`.

---

## What to tell users

- Treat it as first-party: every section of this skill applies unchanged. Do **not** apply Bedrock's feature-availability mask.
- Model IDs are bare (`claude-opus-4-8`). Do **not** add an `anthropic.` prefix.
- A missing region or `workspace_id` throws at client-construction time (no request is sent). A **403** means the request reached the server — check for a **wrong** `workspace_id` or a missing IAM action on the principal. See the IAM actions reference in `shared/live-sources.md`.

FILE:shared/error-codes.md
# HTTP Error Codes Reference

This file documents HTTP error codes returned by the Claude API, their common causes, and how to handle them. For language-specific error handling examples, see the `python/` or `typescript/` folders.

## Error Code Summary

| Code | Error Type              | Retryable | Common Cause                         |
| ---- | ----------------------- | --------- | ------------------------------------ |
| 400  | `invalid_request_error` | No        | Invalid request format or parameters |
| 401  | `authentication_error`  | No        | Invalid or missing API key           |
| 403  | `permission_error`      | No        | API key lacks permission             |
| 404  | `not_found_error`       | No        | Invalid endpoint or model ID         |
| 413  | `request_too_large`     | No        | Request exceeds size limits          |
| 429  | `rate_limit_error`      | Yes       | Too many requests                    |
| 500  | `api_error`             | Yes       | Anthropic service issue              |
| 529  | `overloaded_error`      | Yes       | API is temporarily overloaded        |

## Detailed Error Information

### 400 Bad Request

**Causes:**

- Malformed JSON in request body
- Missing required parameters (`model`, `max_tokens`, `messages`)
- Invalid parameter types (e.g., string where integer expected)
- Empty messages array
- Messages not alternating user/assistant

**Example error:**

```json
{
  "type": "error",
  "error": {
    "type": "invalid_request_error",
    "message": "messages: roles must alternate between \"user\" and \"assistant\""
  },
  "request_id": "req_011CSHoEeqs5C35K2UUqR7Fy"
}
```

**Fix:** Validate request structure before sending. Check that:

- `model` is a valid model ID
- `max_tokens` is a positive integer
- `messages` array is non-empty and alternates correctly

---

### 401 Unauthorized

**Causes:**

- Missing `x-api-key` header or `Authorization` header
- Invalid API key format
- Revoked or deleted API key
- OAuth bearer token sent via `x-api-key` instead of `Authorization: Bearer`
- Both `ANTHROPIC_API_KEY` and `ANTHROPIC_AUTH_TOKEN` set — the SDK sends both headers and the API rejects the request

**Fix:** Set `ANTHROPIC_API_KEY`, or run `ant auth login` and leave the client constructor empty. For raw HTTP with an OAuth token, use `Authorization: Bearer <token>` (not `x-api-key:`).

---

### 403 Forbidden

**Causes:**

- API key doesn't have access to the requested model
- Organization-level restrictions
- Attempting to access beta features without beta access

**Fix:** Check your API key permissions in the Console. You may need a different API key or to request access to specific features.

---

### 404 Not Found

**Causes:**

- Typo in model ID (e.g., `claude-sonnet-4.6` instead of `claude-sonnet-4-6`)
- Using deprecated model ID
- Invalid API endpoint

**Fix:** Use exact model IDs from the models documentation. You can use aliases (e.g., `claude-opus-4-8`).

---

### 413 Request Too Large

**Causes:**

- Request body exceeds maximum size
- Too many tokens in input
- Image data too large

**Fix:** Reduce input size — truncate conversation history, compress/resize images, or split large documents into chunks.

---

### 400 Validation Errors

Some 400 errors are specifically related to parameter validation:

- `max_tokens` exceeds model's limit
- Invalid `temperature` value (must be 0.0-1.0)
- `budget_tokens` >= `max_tokens` in extended thinking
- Invalid tool definition schema

**Model-specific 400s on Fable 5 / Opus 4.8 / 4.7:**

- `temperature`, `top_p`, `top_k` are removed — sending any of them returns 400. Delete the parameter; see `shared/model-migration.md` → Per-SDK Syntax Reference.
- `thinking: {type: "enabled", budget_tokens: N}` is removed — sending it returns 400. Use `thinking: {type: "adaptive"}` instead.
- **Fable 5 only:** an explicit `thinking: {type: "disabled"}` returns 400 (it is accepted on Opus 4.8/4.7). Omit the `thinking` param entirely instead.
- **Fable 5 only:** if the organization is set to zero data retention (ZDR) — or any retention below the required 30 days — then **all** Fable 5 requests return `400 invalid_request_error`, even with a perfectly valid payload. Check the org's retention configuration before debugging the request body.

**Common mistake with extended thinking on older models (Opus 4.6 and earlier):**

```
# Wrong: budget_tokens must be < max_tokens
thinking: budget_tokens=10000, max_tokens=1000  → Error!

# Correct
thinking: budget_tokens=10000, max_tokens=16000
```

---

### 429 Rate Limited

**Causes:**

- Exceeded requests per minute (RPM)
- Exceeded tokens per minute (TPM)
- Exceeded tokens per day (TPD)

**Headers to check:**

- `retry-after`: Seconds to wait before retrying
- `x-ratelimit-limit-*`: Your limits
- `x-ratelimit-remaining-*`: Remaining quota

**Fix:** The Anthropic SDKs automatically retry 429 and 5xx errors with exponential backoff (default: `max_retries=2`). For custom retry behavior, see the language-specific error handling examples.

---

### 500 Internal Server Error

**Causes:**

- Temporary Anthropic service issue
- Bug in API processing

**Fix:** Retry with exponential backoff. If persistent, check [status.anthropic.com](https://status.anthropic.com).

---

### 529 Overloaded

**Causes:**

- High API demand
- Service capacity reached

**Fix:** Retry with exponential backoff. Consider using a different model (Haiku is often less loaded), spreading requests over time, or implementing request queuing.

---

## Common Mistakes and Fixes

| Mistake                         | Error            | Fix                                                     |
| ------------------------------- | ---------------- | ------------------------------------------------------- |
| `temperature`/`top_p`/`top_k` on Fable 5 / Opus 4.8 / 4.7 | 400 | Remove the parameter (see `shared/model-migration.md`)  |
| `budget_tokens` on Fable 5 / Opus 4.8 / 4.7 | 400  | Use `thinking: {type: "adaptive"}`                      |
| `thinking: {type: "disabled"}` on Fable 5 | 400    | Omit the `thinking` param entirely (accepted on Opus 4.8/4.7) |
| Org set to ZDR / retention below 30 days (Fable 5) | 400 on every request | Fix the org's data-retention configuration — the payload isn't the problem |
| `budget_tokens` >= `max_tokens` (older models) | 400 | Ensure `budget_tokens` < `max_tokens`                  |
| Typo in model ID                | 404              | Use valid model ID like `claude-opus-4-8`               |
| First message is `assistant`    | 400              | First message must be `user`                            |
| Consecutive same-role messages  | 400              | Alternate `user` and `assistant`                        |
| API key in code                 | 401 (leaked key) | Use environment variable                                |
| Custom retry needs              | 429/5xx          | SDK retries automatically; customize with `max_retries` |

## Typed Exceptions in SDKs

**Always use the SDK's typed exception classes** instead of checking error messages with string matching. Each HTTP error code maps to a specific exception class:

| HTTP Code | TypeScript Class                  | Python Class                      |
| --------- | --------------------------------- | --------------------------------- |
| 400       | `Anthropic.BadRequestError`       | `anthropic.BadRequestError`       |
| 401       | `Anthropic.AuthenticationError`   | `anthropic.AuthenticationError`   |
| 403       | `Anthropic.PermissionDeniedError` | `anthropic.PermissionDeniedError` |
| 404       | `Anthropic.NotFoundError`         | `anthropic.NotFoundError`         |
| 413       | `Anthropic.RequestTooLargeError`  | `anthropic.RequestTooLargeError`  |
| 429       | `Anthropic.RateLimitError`        | `anthropic.RateLimitError`        |
| 500+      | `Anthropic.InternalServerError`   | `anthropic.InternalServerError`   |
| 529       | `Anthropic.OverloadedError`       | `anthropic.OverloadedError`       |
| Any       | `Anthropic.APIError`              | `anthropic.APIError`              |

```typescript
// ✅ Correct: use typed exceptions
try {
  const response = await client.messages.create({...});
} catch (error) {
  if (error instanceof Anthropic.RateLimitError) {
    // Handle rate limiting
  } else if (error instanceof Anthropic.APIError) {
    console.error(`API error error.status:`, error.message);
  }
}

// ❌ Wrong: don't check error messages with string matching
try {
  const response = await client.messages.create({...});
} catch (error) {
  const msg = error instanceof Error ? error.message : String(error);
  if (msg.includes("429") || msg.includes("rate_limit")) { ... }
}
```

All exception classes extend `Anthropic.APIError`, which has a `status` property. Use `instanceof` checks from most specific to least specific (e.g., check `RateLimitError` before `APIError`).

### Error `.type` Field

All `APIStatusError` subclasses now expose a `.type` property (Python: `.type`, TypeScript: `.type`, Java: `.errorType()`, Go: `.Type()`, Ruby: `.type`, PHP: `.type`) that returns the API error type string (e.g., `"invalid_request_error"`, `"authentication_error"`, `"rate_limit_error"`, `"overloaded_error"`). Use this for programmatic error classification when you need finer granularity than the HTTP status code — for example, distinguishing `"billing_error"` from `"permission_error"` (both map to 403).

```python
except anthropic.APIStatusError as e:
    if e.type == "rate_limit_error":
        # handle rate limiting
    elif e.type == "overloaded_error":
        # handle overload
```

FILE:shared/live-sources.md
# Live Documentation Sources

This file contains WebFetch URLs for fetching current information from platform.claude.com and Agent SDK repositories. Use these when users need the latest data that may have changed since the cached content was last updated.

## When to Use WebFetch

- User explicitly asks for "latest" or "current" information
- Cached data seems incorrect
- User asks about features not covered in cached content
- User needs specific API details or examples

## Claude API Documentation URLs

### Models & Pricing

| Topic           | URL                                                                          | Extraction Prompt                                                               |
| --------------- | ---------------------------------------------------------------------------- | ------------------------------------------------------------------------------- |
| Models Overview | `https://platform.claude.com/docs/en/about-claude/models/overview.md`        | "Extract current model IDs, context windows, and pricing for all Claude models" |
| Migration Guide | `https://platform.claude.com/docs/en/about-claude/models/migration-guide.md` | "Extract breaking changes, deprecated parameters, and per-model migration steps when moving to a newer Claude model" |
| Introducing Claude Fable 5 | `https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5.md` | "Extract capabilities, API changes, and availability stages for Claude Fable 5 and Claude Mythos 5" |
| Pricing         | `https://platform.claude.com/docs/en/pricing.md`                             | "Extract current pricing per million tokens for input and output"               |

### Core Features

| Topic             | URL                                                                          | Extraction Prompt                                                                      |
| ----------------- | ---------------------------------------------------------------------------- | -------------------------------------------------------------------------------------- |
| Extended Thinking | `https://platform.claude.com/docs/en/build-with-claude/extended-thinking.md` | "Extract extended thinking parameters, budget_tokens requirements, and usage examples" |
| Adaptive Thinking | `https://platform.claude.com/docs/en/build-with-claude/adaptive-thinking.md` | "Extract adaptive thinking setup, effort levels, and Claude Opus 4.8 usage examples"         |
| Effort Parameter  | `https://platform.claude.com/docs/en/build-with-claude/effort.md`            | "Extract effort levels, cost-quality tradeoffs, and interaction with thinking"        |
| Tool Use          | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview.md`  | "Extract tool definition schema, tool_choice options, and handling tool results"       |
| Streaming         | `https://platform.claude.com/docs/en/build-with-claude/streaming.md`         | "Extract streaming event types, SDK examples, and best practices"                      |
| Prompt Caching    | `https://platform.claude.com/docs/en/build-with-claude/prompt-caching.md`    | "Extract cache_control usage, pricing benefits, and implementation examples"           |

### Media & Files

| Topic       | URL                                                                    | Extraction Prompt                                                 |
| ----------- | ---------------------------------------------------------------------- | ----------------------------------------------------------------- |
| Vision      | `https://platform.claude.com/docs/en/build-with-claude/vision.md`      | "Extract supported image formats, size limits, and code examples" |
| PDF Support | `https://platform.claude.com/docs/en/build-with-claude/pdf-support.md` | "Extract PDF handling capabilities, limits, and examples"         |

### API Operations

| Topic            | URL                                                                         | Extraction Prompt                                                                                       |
| ---------------- | --------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------- |
| Batch Processing | `https://platform.claude.com/docs/en/build-with-claude/batch-processing.md` | "Extract batch API endpoints, request format, and polling for results"                                  |
| Files API        | `https://platform.claude.com/docs/en/build-with-claude/files.md`            | "Extract file upload, download, and referencing in messages, including supported types and beta header" |
| Token Counting   | `https://platform.claude.com/docs/en/build-with-claude/token-counting.md`   | "Extract token counting API usage and examples"                                                         |
| Rate Limits      | `https://platform.claude.com/docs/en/api/rate-limits.md`                    | "Extract current rate limits by tier and model"                                                         |
| Errors           | `https://platform.claude.com/docs/en/api/errors.md`                         | "Extract HTTP error codes, meanings, and retry guidance"                                                |
| Amazon Bedrock   | `https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock.md` | "Extract the AnthropicBedrockMantle client per language, `anthropic.`-prefixed model IDs, auth paths, feature availability, and regions" |
| Claude Platform on AWS | `https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws.md` | "Extract the AnthropicAWS client per language, SigV4 auth, credential precedence, short-term API keys, workspace_id, and region requirements" |
| Claude Platform on AWS — IAM actions | `https://platform.claude.com/docs/en/api/claude-platform-on-aws-iam-actions.md` | "Extract the IAM action names, resource ARNs, and policy examples required for each API capability" |

### Tools

| Topic          | URL                                                                                    | Extraction Prompt                                                                        |
| -------------- | -------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------- |
| Code Execution | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool.md` | "Extract code execution tool setup, file upload, container reuse, and response handling" |
| Computer Use   | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use.md`        | "Extract computer use tool setup, capabilities, and implementation examples"             |
| Bash Tool      | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/bash-tool.md`           | "Extract bash tool schema, reference implementation, and security considerations"        |
| Text Editor    | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/text-editor-tool.md`    | "Extract text editor tool commands, schema, and reference implementation"                |
| Memory Tool    | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/memory-tool.md`         | "Extract memory tool commands, directory structure, and implementation patterns"         |
| Tool Search    | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-search-tool.md`    | "Extract tool search setup, when to use, and cache interaction"                          |
| Programmatic Tool Calling | `https://platform.claude.com/docs/en/agents-and-tools/tool-use/programmatic-tool-calling.md` | "Extract PTC setup, script execution model, and tool invocation from code"    |
| Skills         | `https://platform.claude.com/docs/en/agents-and-tools/skills.md`                       | "Extract skill folder structure, SKILL.md format, and loading behavior"                  |

### Advanced Features

| Topic              | URL                                                                           | Extraction Prompt                                   |
| ------------------ | ----------------------------------------------------------------------------- | --------------------------------------------------- |
| Structured Outputs | `https://platform.claude.com/docs/en/build-with-claude/structured-outputs.md` | "Extract output_config.format usage and schema enforcement"                           |
| Compaction         | `https://platform.claude.com/docs/en/build-with-claude/compaction.md`         | "Extract compaction setup, trigger config, and streaming with compaction"             |
| Context Editing    | `https://platform.claude.com/docs/en/build-with-claude/context-editing.md`    | "Extract context editing thresholds, what gets cleared, and configuration"            |
| Citations          | `https://platform.claude.com/docs/en/build-with-claude/citations.md`          | "Extract citation format and implementation"        |
| Context Windows    | `https://platform.claude.com/docs/en/build-with-claude/context-windows.md`    | "Extract context window sizes and token management" |

### Managed Agents

Use these when a managed-agents binding, behavior, or wire-level detail isn't covered in the cached `shared/managed-agents-*.md` concept files or in `{lang}/managed-agents/README.md`.

| Topic                 | URL                                                                              | Extraction Prompt                                                                               |
| --------------------- | -------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------- |
| Overview              | `https://platform.claude.com/docs/en/managed-agents/overview.md`                 | "Extract the high-level architecture and how agents/sessions/environments/vaults fit together" |
| Quickstart            | `https://platform.claude.com/docs/en/managed-agents/quickstart.md`               | "Extract the minimal end-to-end agent → environment → session → stream code path"              |
| Agent Setup           | `https://platform.claude.com/docs/en/managed-agents/agent-setup.md`              | "Extract agent create/update/list-versions/archive lifecycle and parameters"                   |
| Define Outcomes       | `https://platform.claude.com/docs/en/managed-agents/define-outcomes.md`          | "Extract outcome definitions, evaluation hooks, and success criteria configuration"             |
| Sessions              | `https://platform.claude.com/docs/en/managed-agents/sessions.md`                 | "Extract session lifecycle, status transitions, idle/terminated semantics, and resume rules"    |
| Environments          | `https://platform.claude.com/docs/en/managed-agents/environments.md`             | "Extract environment config (cloud/networking), management endpoints, and reuse model"          |
| Self-Hosted Sandboxes | `https://platform.claude.com/docs/en/managed-agents/self-hosted-sandboxes.md`    | "Extract config:{type:self_hosted}, ANTHROPIC_ENVIRONMENT_KEY, EnvironmentWorker.run/run_one, beta_agent_toolset, ant beta:worker poll/run, webhook-driven wake" |
| Self-Hosted Sandboxes — Security | `https://platform.claude.com/docs/en/managed-agents/self-hosted-sandboxes-security.md` | "Extract what the customer owns (hardening, egress, key custody, trust boundaries) vs what Anthropic cannot do" |
| Events and Streaming  | `https://platform.claude.com/docs/en/managed-agents/events-and-streaming.md`     | "Extract event stream types, stream-first ordering, reconnect/dedupe, and steering patterns"    |
| Tools                 | `https://platform.claude.com/docs/en/managed-agents/tools.md`                    | "Extract built-in toolset, custom tool definitions, and tool result wire format"                |
| Files                 | `https://platform.claude.com/docs/en/managed-agents/files.md`                    | "Extract file upload, mount paths, session resources, and listing/downloading session outputs"  |
| Permission Policies   | `https://platform.claude.com/docs/en/managed-agents/permission-policies.md`      | "Extract permission policy types (allow/deny/confirm) and per-tool config"                     |
| Multi-Agent           | `https://platform.claude.com/docs/en/managed-agents/multi-agent.md`              | "Extract multi-agent composition patterns, sub-agent invocation, and result handoff"            |
| Observability         | `https://platform.claude.com/docs/en/managed-agents/observability.md`            | "Extract logging, tracing, and usage telemetry exposed by managed agents"                       |
| Webhooks              | `https://platform.claude.com/docs/en/managed-agents/webhooks.md`                 | "Extract webhook endpoint registration, HMAC signature verification, supported event types, and delivery semantics" |
| GitHub                | `https://platform.claude.com/docs/en/managed-agents/github.md`                   | "Extract github_repository resource shape, multi-repo mounting, and token rotation"             |
| MCP Connector         | `https://platform.claude.com/docs/en/managed-agents/mcp-connector.md`            | "Extract MCP server declaration on agents and vault-based credential injection at session"     |
| Vaults                | `https://platform.claude.com/docs/en/managed-agents/vaults.md`                   | "Extract vault create, credential add/rotate, OAuth refresh shape, and archive"                 |
| Skills                | `https://platform.claude.com/docs/en/managed-agents/skills.md`                   | "Extract skill packaging and loading model for managed agents"                                  |
| Memory                | `https://platform.claude.com/docs/en/managed-agents/memory.md`                   | "Extract memory resource shape, scoping, and lifecycle"                                         |
| Onboarding            | `https://platform.claude.com/docs/en/managed-agents/onboarding.md`               | "Extract first-run setup, prerequisites, and account/region requirements"                      |
| Cloud Containers      | `https://platform.claude.com/docs/en/managed-agents/cloud-containers.md`         | "Extract cloud container runtime, image config, and network/storage knobs"                     |
| Migration             | `https://platform.claude.com/docs/en/managed-agents/migration.md`                | "Extract migration paths from earlier APIs/preview shapes to GA managed agents"                 |

### Anthropic CLI

The `ant` CLI provides terminal access to the Claude API. Every API resource is exposed as a subcommand. It is one convenient way to create agents, environments, sessions, and other resources from version-controlled YAML, and to inspect responses interactively.

| Topic         | URL                                                     | Extraction Prompt                                                                                  |
| ------------- | ------------------------------------------------------- | -------------------------------------------------------------------------------------------------- |
| Anthropic CLI | `https://platform.claude.com/docs/en/api/sdks/cli.md`   | "Extract CLI install, authentication, command structure, and the beta:agents/environments/sessions commands" |
| Authentication overview | `https://platform.claude.com/docs/en/manage-claude/authentication.md` | "Extract the credential options (API keys, interactive OAuth login, Workload Identity Federation) and when to use each" |
| WIF reference | `https://platform.claude.com/docs/en/manage-claude/wif-reference.md`  | "Extract credential precedence order, the profile configuration file schema, and the configuration directory layout" |

---

## Claude API SDK Repositories

WebFetch these when a binding (class, method, namespace, field) isn't covered in the cached `{lang}/` skill files or in the managed-agents docs above. The SDKs include beta managed-agents support for `/v1/agents`, `/v1/sessions`, `/v1/environments`, and related resources — search the repo for `BetaManagedAgents`, `beta.agents`, `beta.sessions`, or the equivalent namespace for that language.

| SDK        | URL                                                      | Extraction Prompt                                                                                                       |
| ---------- | -------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
| Python     | `https://github.com/anthropics/anthropic-sdk-python`     | "Extract beta managed-agents namespaces, classes, and method signatures (`client.beta.agents`, `client.beta.sessions`)" |
| TypeScript | `https://github.com/anthropics/anthropic-sdk-typescript` | "Extract beta managed-agents namespaces, classes, and method signatures (`client.beta.agents`, `client.beta.sessions`)" |
| Java       | `https://github.com/anthropics/anthropic-sdk-java`       | "Extract beta managed-agents classes, builders, and method signatures (`client.beta().agents()`, `BetaManagedAgents*`)" |
| Go         | `https://github.com/anthropics/anthropic-sdk-go`         | "Extract beta managed-agents types and method signatures (`client.Beta.Agents`, `BetaManagedAgents*` event types)"      |
| Ruby       | `https://github.com/anthropics/anthropic-sdk-ruby`       | "Extract beta managed-agents methods and parameter shapes (`client.beta.agents`, `client.beta.sessions`)"               |
| C#         | `https://github.com/anthropics/anthropic-sdk-csharp`     | "Extract beta managed-agents classes and method signatures (NuGet package, `BetaManagedAgents*` types)"                 |
| PHP        | `https://github.com/anthropics/anthropic-sdk-php`        | "Extract beta managed-agents classes and method signatures (`$client->beta->agents`, `BetaManagedAgents*` params)"      |

Each SDK repo also ships runnable programs under `examples/` — including the refusal-fallback / `fallbacks` examples (client-side middleware registration, fallback state, server-side `fallbacks` param). Fetch those for exact per-language syntax instead of translating another language's example.

---

## Fallback Strategy

If WebFetch fails (network issues, URL changed):

1. Use cached content from the language-specific files (note the cache date)
2. Inform user the data may be outdated
3. Suggest they check platform.claude.com or the GitHub repos directly

FILE:shared/managed-agents-api-reference.md
# Managed Agents — Endpoint Reference

All endpoints require `x-api-key` and `anthropic-version: 2023-06-01` headers. Managed Agents endpoints additionally require the `anthropic-beta` header.

## Beta Headers

```
anthropic-beta: managed-agents-2026-04-01
```

The SDK adds this header automatically for all `client.beta.{agents,environments,sessions,vaults,memory_stores,deployments,deployment_runs}.*` calls. Skills endpoints use `skills-2025-10-02`; Files endpoints use `files-api-2025-04-14`.

---

## SDK Method Reference

All resources are under the `beta` namespace. Python and TypeScript share identical method names.

| Resource | Python / TypeScript (`client.beta.*`) | Go (`client.Beta.*`) |
| --- | --- | --- |
| Agents | `agents.create` / `retrieve` / `update` / `list` / `archive` | `Agents.New` / `Get` / `Update` / `List` / `Archive` |
| Agent Versions | `agents.versions.list` | `Agents.Versions.List` |
| Environments | `environments.create` / `retrieve` / `update` / `list` / `delete` / `archive` | `Environments.New` / `Get` / `Update` / `List` / `Delete` / `Archive` |
| Environment Work (self-hosted) | `environments.work.poller` / `stats` / `stop` | See `shared/managed-agents-self-hosted-sandboxes.md` |
| Sessions | `sessions.create` / `retrieve` / `update` / `list` / `delete` / `archive` | `Sessions.New` / `Get` / `Update` / `List` / `Delete` / `Archive` |
| Session Events | `sessions.events.list` / `send` / `stream` | `Sessions.Events.List` / `Send` / `StreamEvents` |
| Session Threads | `sessions.threads.list` / `retrieve` / `archive`; `sessions.threads.events.list` / `stream` | `Sessions.Threads.List` / `Get` / `Archive`; `Sessions.Threads.Events.List` / `StreamEvents` |
| Session Resources | `sessions.resources.add` / `retrieve` / `update` / `list` / `delete` | `Sessions.Resources.Add` / `Get` / `Update` / `List` / `Delete` |
| Deployments | `deployments.create` / `pause` / `unpause` / `archive` / `run` | Not yet documented — WebFetch the SDK repo (`shared/live-sources.md`) |
| Deployment Runs | `deployment_runs.list` (TS: `deploymentRuns.list`) | Not yet documented — WebFetch the SDK repo (`shared/live-sources.md`) |
| Vaults | `vaults.create` / `retrieve` / `update` / `list` / `delete` / `archive` | `Vaults.New` / `Get` / `Update` / `List` / `Delete` / `Archive` |
| Credentials | `vaults.credentials.create` / `retrieve` / `update` / `list` / `delete` / `archive` / `mcp_oauth_validate` | `Vaults.Credentials.New` / `Get` / `Update` / `List` / `Delete` / `Archive` / `McpOauthValidate` |
| Memory Stores | `memory_stores.create` / `retrieve` / `update` / `list` / `delete` / `archive` | `MemoryStores.New` / `Get` / `Update` / `List` / `Delete` / `Archive` |
| Memories | `memory_stores.memories.create` / `retrieve` / `update` / `list` / `delete` | `MemoryStores.Memories.New` / `Get` / `Update` / `List` / `Delete` |
| Memory Versions | `memory_stores.memory_versions.list` / `retrieve` / `redact` | `MemoryStores.MemoryVersions.List` / `Get` / `Redact` |

**Naming quirks to watch for:**
- Agents and Session Threads have **no delete** — only `archive`. Archive is **permanent**: the agent becomes read-only, new sessions cannot reference it, and there is no unarchive. Confirm with the user before archiving a production agent. Environments, Sessions, Vaults, Credentials, and Memory Stores have both `delete` and `archive`; Session Resources, Files, Skills, and Memories are `delete`-only; Memory Versions have neither — only `redact`.
- Session resources use `add` (not `create`).
- Go's event stream is `StreamEvents` (not `Stream`).
- The self-hosted worker is **not** under `client.beta.*` — it's `EnvironmentWorker` from `anthropic.lib.environments` / `@anthropic-ai/sdk/helpers/beta/environments`; only `environments.work.poller/stats/stop` are client methods.

**Agent shorthand:** `agent` on session create accepts either a bare string (`agent="agent_abc123"` — uses latest version) or the full reference object (`{type: "agent", id: "agent_abc123", version: 123}`).

**Model shorthand:** `model` on agent create accepts either a bare string (`model="claude-opus-4-8"` — uses `standard` speed) or the full config object (`{id: "claude-opus-4-6", speed: "fast"}`). Note: `speed: "fast"` is only supported on Opus 4.6.

---

## Agents

**Step one of every flow.** Sessions require a pre-created agent — there is no inline agent config under `managed-agents-2026-04-01`.

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `GET` | `/v1/agents` | ListAgents | List agents |
| `POST` | `/v1/agents` | CreateAgent | Create a saved agent configuration |
| `GET` | `/v1/agents/{agent_id}` | GetAgent | Get agent details |
| `POST` | `/v1/agents/{agent_id}` | UpdateAgent | Update agent configuration |
| `POST` | `/v1/agents/{agent_id}/archive` | ArchiveAgent | Archive an agent. Makes it **read-only**; existing sessions continue, new sessions cannot reference it. No unarchive — this is the terminal state. |
| `GET` | `/v1/agents/{agent_id}/versions` | ListAgentVersions | List agent versions |

## Sessions

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `GET` | `/v1/sessions` | ListSessions | List sessions (paginated) |
| `POST` | `/v1/sessions` | CreateSession | Create a new session |
| `GET` | `/v1/sessions/{session_id}` | GetSession | Get session details |
| `POST` | `/v1/sessions/{session_id}` | UpdateSession | Update session `metadata`/`title`, or `agent.tools`/`agent.mcp_servers`/`vault_ids` (session-local override; session must be `idle`). See `shared/managed-agents-core.md` → Updating the agent configuration mid-session. |
| `DELETE` | `/v1/sessions/{session_id}` | DeleteSession | Delete a session |
| `POST` | `/v1/sessions/{session_id}/archive` | ArchiveSession | Archive a session |

## Events

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `GET` | `/v1/sessions/{session_id}/events` | ListEvents | List events (polling, paginated) |
| `POST` | `/v1/sessions/{session_id}/events` | SendEvents | Send events (user message, tool result) |
| `GET` | `/v1/sessions/{session_id}/events/stream` | StreamEvents | Stream events via SSE |

## Session Threads

Per-subagent event streams in multiagent sessions. See `shared/managed-agents-multiagent.md`.

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `GET` | `/v1/sessions/{session_id}/threads` | ListThreads | List threads (paginated) |
| `GET` | `/v1/sessions/{session_id}/threads/{thread_id}` | GetThread | Retrieve one thread (carries `agent` snapshot, `status`, `parent_thread_id`, `stats`, `usage`) |
| `POST` | `/v1/sessions/{session_id}/threads/{thread_id}/archive` | ArchiveThread | Archive a thread |
| `GET` | `/v1/sessions/{session_id}/threads/{thread_id}/events` | ListThreadEvents | List past events for one thread (paginated) |
| `GET` | `/v1/sessions/{session_id}/threads/{thread_id}/stream` | StreamThreadEvents | Stream one thread via SSE (SDK: `threads.events.stream`) |

## Session Resources

| Method   | Path                                                    | Operation        | Description                              |
| -------- | ------------------------------------------------------- | ---------------- | ---------------------------------------- |
| `GET` | `/v1/sessions/{session_id}/resources` | ListResources | List resources attached to session |
| `POST` | `/v1/sessions/{session_id}/resources` | AddResource | Attach `file` or `github_repository` resource (SDK method: `add`, not `create`). `memory_store` resources attach at session-create time only. |
| `GET` | `/v1/sessions/{session_id}/resources/{resource_id}` | GetResource | Get a single resource |
| `POST` | `/v1/sessions/{session_id}/resources/{resource_id}` | UpdateResource | Update resource |
| `DELETE` | `/v1/sessions/{session_id}/resources/{resource_id}` | DeleteResource | Remove resource from session |

## Environments

| Method   | Path                                                             | Operation            | Description                         |
| -------- | ---------------------------------------------------------------- | -------------------- | ----------------------------------- |
| `POST`   | `/v1/environments`                                     | CreateEnvironment    | Create environment                  |
| `GET`    | `/v1/environments`                                     | ListEnvironments     | List environments                   |
| `GET`    | `/v1/environments/{environment_id}`                    | GetEnvironment       | Get environment details             |
| `POST`   | `/v1/environments/{environment_id}`                    | UpdateEnvironment    | Update environment                  |
| `DELETE` | `/v1/environments/{environment_id}`                    | DeleteEnvironment    | Delete environment. Returns 204. |
| `POST`   | `/v1/environments/{environment_id}/archive`            | ArchiveEnvironment   | Archive environment. Makes it **read-only**; existing sessions continue, new sessions cannot reference it. No unarchive — this is the terminal state. |
| `GET`    | `/v1/environments/{environment_id}/work/stats`         | WorkQueueStats       | Self-hosted work-queue depth/pending/workers. `x-api-key` auth. See `shared/managed-agents-self-hosted-sandboxes.md`. |
| `POST`   | `/v1/environments/{environment_id}/work/{work_id}/stop` | StopWork            | Self-hosted: stop a claimed work item. `x-api-key` auth. |

For `type: "self_hosted"`, `config` is the bare `{"type": "self_hosted"}` — `networking` and `packages` do not apply.

## Deployments

Scheduled deployments (`depl_` IDs) run an agent on a recurring cron schedule — each firing creates a session. See `shared/managed-agents-scheduled-deployments.md` for the conceptual guide (cron/DST semantics, failure behavior, lifecycle).

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `POST`   | `/v1/deployments`                                | CreateDeployment | Create a scheduled deployment            |
| `POST`   | `/v1/deployments/{deployment_id}/pause`          | PauseDeployment  | Suppress scheduled triggers (reversible; manual runs still allowed) |
| `POST`   | `/v1/deployments/{deployment_id}/unpause`        | UnpauseDeployment | Resume from the next occurrence (no backfill) |
| `POST`   | `/v1/deployments/{deployment_id}/archive`        | ArchiveDeployment | **Terminal** — schedule stops, deployment becomes immutable |
| `POST`   | `/v1/deployments/{deployment_id}/run`            | RunDeployment    | Trigger a manual run immediately (`trigger_context.type: "manual"`); works while paused |

## Deployment Runs

Each trigger attempt (scheduled or manual) writes a `deployment_run` record (`drun_` IDs) carrying either the created `session_id` or an `error.type` (`environment_archived`, `agent_archived`, `vault_not_found`, `session_rate_limited`, `service_unavailable`).

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `GET`    | `/v1/deployment_runs?deployment_id=...`          | ListDeploymentRuns | List runs for a deployment (paginated; filter failures with `has_error=true`) |

## Vaults

Vaults store credentials that Anthropic manages on your behalf — MCP credentials (OAuth with auto-refresh, or static bearer tokens) and `environment_variable` credentials substituted into outbound requests at egress. Attach to sessions via `vault_ids`. See `managed-agents-tools.md` §Vaults for the conceptual guide and credential shapes.

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `POST`   | `/v1/vaults`                                     | CreateVault      | Create a vault                           |
| `GET`    | `/v1/vaults`                                     | ListVaults       | List vaults                              |
| `GET`    | `/v1/vaults/{vault_id}`                          | GetVault         | Get vault details                        |
| `POST`   | `/v1/vaults/{vault_id}`                          | UpdateVault      | Update vault                             |
| `DELETE` | `/v1/vaults/{vault_id}`                          | DeleteVault      | Delete vault                             |
| `POST`   | `/v1/vaults/{vault_id}/archive`                  | ArchiveVault     | Archive vault                            |

## Credentials

Credentials are individual secrets stored inside a vault.

| Method   | Path                                                              | Operation          | Description                  |
| -------- | ----------------------------------------------------------------- | ------------------ | ---------------------------- |
| `POST`   | `/v1/vaults/{vault_id}/credentials`                               | CreateCredential   | Create a credential          |
| `GET`    | `/v1/vaults/{vault_id}/credentials`                               | ListCredentials    | List credentials in vault    |
| `GET`    | `/v1/vaults/{vault_id}/credentials/{credential_id}`               | GetCredential      | Get credential metadata      |
| `POST`   | `/v1/vaults/{vault_id}/credentials/{credential_id}`               | UpdateCredential   | Update credential            |
| `DELETE` | `/v1/vaults/{vault_id}/credentials/{credential_id}`               | DeleteCredential   | Delete credential            |
| `POST`   | `/v1/vaults/{vault_id}/credentials/{credential_id}/archive`       | ArchiveCredential  | Archive credential           |
| `POST`   | `/v1/vaults/{vault_id}/credentials/{credential_id}/mcp_oauth_validate` | McpOauthValidate | Validate an MCP OAuth credential |

## Memory Stores

Workspace-scoped persistent memory that survives across sessions. Attach to a session via a `{"type": "memory_store", "memory_store_id": ...}` entry in `resources[]` (session-create time only). See `shared/managed-agents-memory.md` for the conceptual guide, the FUSE-mount agent interface, preconditions, and versioning.

| Method   | Path                                             | Operation          | Description                              |
| -------- | ------------------------------------------------ | ------------------ | ---------------------------------------- |
| `POST`   | `/v1/memory_stores`                              | CreateMemoryStore  | Create a store (`name`, `description`, `metadata`) |
| `GET`    | `/v1/memory_stores`                              | ListMemoryStores   | List stores (`include_archived`, `created_at_{gte,lte}`) |
| `GET`    | `/v1/memory_stores/{memory_store_id}`            | GetMemoryStore     | Get store details                        |
| `POST`   | `/v1/memory_stores/{memory_store_id}`            | UpdateMemoryStore  | Update store                             |
| `DELETE` | `/v1/memory_stores/{memory_store_id}`            | DeleteMemoryStore  | Delete store                             |
| `POST`   | `/v1/memory_stores/{memory_store_id}/archive`    | ArchiveMemoryStore | Archive store. Makes it **read-only**; existing sessions continue, new sessions cannot reference it. No unarchive. |

## Memories

Individual text documents inside a store (≤ 100KB each). `create` creates at a `path` and returns `409` (`memory_path_conflict_error`, with `conflicting_memory_id`) if the path is occupied; `update` mutates by `mem_...` ID (rename and/or content). Only `update` accepts a `precondition` (`{"type": "content_sha256", "content_sha256": ...}`) — on mismatch returns `409` (`memory_precondition_failed_error`). List endpoints accept `view: "basic"|"full"` (controls whether `content` is populated; `retrieve` defaults to `full`).

| Method   | Path                                                              | Operation      | Description                              |
| -------- | ----------------------------------------------------------------- | -------------- | ---------------------------------------- |
| `GET`    | `/v1/memory_stores/{memory_store_id}/memories`                    | ListMemories   | Returns `Memory \| MemoryPrefix`; filter by `path_prefix`, `depth`, `order_by`/`order` |
| `POST`   | `/v1/memory_stores/{memory_store_id}/memories`                    | CreateMemory   | Create at `path` (SDK: `memories.create`); `409 memory_path_conflict_error` if occupied |
| `GET`    | `/v1/memory_stores/{memory_store_id}/memories/{memory_id}`        | GetMemory      | Read one memory (defaults to `view="full"`) |
| `PATCH`  | `/v1/memory_stores/{memory_store_id}/memories/{memory_id}`        | UpdateMemory   | Change `content`, `path`, or both by ID; optional `precondition` |
| `DELETE` | `/v1/memory_stores/{memory_store_id}/memories/{memory_id}`        | DeleteMemory   | Delete (optional `expected_content_sha256`) |

## Memory Versions

Immutable per-mutation snapshots (`memver_...`) — the audit and rollback surface. `operation` ∈ `created` / `modified` / `deleted`.

| Method   | Path                                                                          | Operation             | Description                              |
| -------- | ----------------------------------------------------------------------------- | --------------------- | ---------------------------------------- |
| `GET`    | `/v1/memory_stores/{memory_store_id}/memory_versions`                         | ListMemoryVersions    | Newest-first; filter by `memory_id`, `operation`, `session_id`, `api_key_id`, `created_at_{gte,lte}` |
| `GET`    | `/v1/memory_stores/{memory_store_id}/memory_versions/{version_id}`            | GetMemoryVersion      | List fields + full `content`             |
| `POST`   | `/v1/memory_stores/{memory_store_id}/memory_versions/{version_id}/redact`     | RedactMemoryVersion   | Clear `content`/`content_sha256`/`content_size_bytes`/`path`; preserve actor + timestamps |

## Files

| Method   | Path                                             | Operation        | Description                              |
| -------- | ------------------------------------------------ | ---------------- | ---------------------------------------- |
| `POST`   | `/v1/files`                            | UploadFile       | Upload a file                            |
| `GET`    | `/v1/files`                            | ListFiles        | List files                               |
| `GET`    | `/v1/files/{file_id}`                  | GetFile          | Get file metadata (SDK method: `retrieve_metadata`) |
| `GET`    | `/v1/files/{file_id}/content`          | DownloadFile     | Download file content                    |
| `DELETE` | `/v1/files/{file_id}`                  | DeleteFile       | Delete a file                            |

## Skills

| Method   | Path                                                            | Operation          | Description                  |
| -------- | --------------------------------------------------------------- | ------------------ | ---------------------------- |
| `POST`   | `/v1/skills`                                          | CreateSkill        | Create a skill               |
| `GET`    | `/v1/skills`                                          | ListSkills         | List skills                  |
| `GET`    | `/v1/skills/{skill_id}`                               | GetSkill           | Get skill details            |
| `DELETE` | `/v1/skills/{skill_id}`                               | DeleteSkill        | Delete a skill               |
| `POST`   | `/v1/skills/{skill_id}/versions`                      | CreateVersion      | Create skill version         |
| `GET`    | `/v1/skills/{skill_id}/versions`                      | ListVersions       | List skill versions          |
| `GET`    | `/v1/skills/{skill_id}/versions/{version}`            | GetVersion         | Get skill version            |
| `DELETE` | `/v1/skills/{skill_id}/versions/{version}`            | DeleteVersion      | Delete skill version         |

---

## Request/Response Schema Quick Reference

### CreateAgent Request Body

**Always start here.** `model`, `system`, `tools`, `mcp_servers`, `skills` are top-level fields on this object — they do NOT go on the session.

```json
{
  "name": "string (required, 1-256 chars)",
  "model": "claude-opus-4-8 (required — bare string, or {id, speed} object)",
  "description": "string (optional, up to 2048 chars)",
  "system": "string (optional, up to 100,000 chars)",
  "tools": [
    { "type": "agent_toolset_20260401" }
  ],
  "skills": [
    { "type": "anthropic", "skill_id": "xlsx" },
    { "type": "custom", "skill_id": "skill_abc123", "version": "1" }
  ],
  "mcp_servers": [
    {
      "type": "url",
      "name": "github",
      "url": "https://api.githubcopilot.com/mcp/"
    }
  ],
  "multiagent": {
    "type": "coordinator",
    "agents": [
      "agent_abc123",
      { "type": "agent", "id": "agent_def456", "version": 4 },
      { "type": "self" }
    ]
  },
  "metadata": {
    "key": "value (max 16 pairs, keys ≤64 chars, values ≤512 chars)"
  }
}
```

> Limits: `tools` max 128, `skills` max 20, `mcp_servers` max 20 (unique names). `multiagent.agents` 1–20 entries (string ID | `{type:"agent",id,version?}` | `{type:"self"}`) — see `shared/managed-agents-multiagent.md`.

### CreateSession Request Body

```json
{
  "agent": "agent_abc123 (required — string shorthand for latest version, or {type: \"agent\", id, version} object)",
  "environment_id": "env_abc123 (required)",
  "title": "string (optional)",
  "resources": [
    {
      "type": "github_repository",
      "url": "https://github.com/owner/repo (required)",
      "authorization_token": "ghp_... (required)",
      "mount_path": "/workspace/repo (optional — defaults to /workspace/<repo-name>)",
      "checkout": { "type": "branch", "name": "main" }
    }
  ],
  "vault_ids": ["vlt_abc123 (optional — vault credentials: MCP auth + environment variables)"],
  "metadata": {
    "key": "value"
  }
}
```

> The `agent` field accepts only a string ID or `{type: "agent", id, version}` — `model`/`system`/`tools` live on the agent, not here.
>
> **`checkout`** accepts `{type: "branch", name: "..."}` or `{type: "commit", sha: "..."}`. Omit for the repo's default branch.

### CreateEnvironment Request Body

```json
{
  "name": "string (required)",
  "description": "string (optional)",
  "config": {
    "type": "cloud | self_hosted",
    "networking": {
      "type": "unrestricted | limited (union — see SDK types)"
    },
    "packages": { }
  },
  "metadata": { "key": "value" }
}
```

### CreateDeployment Request Body

```json
{
  "name": "Weekly compliance scan",
  "agent": "agent_abc123 (required — same shapes as CreateSession)",
  "environment_id": "env_abc123 (required)",
  "initial_events": [
    { "type": "user.message", "content": [{ "type": "text", "text": "Run the weekly compliance scan." }] }
  ],
  "schedule": {
    "type": "cron",
    "expression": "0 20 * * 5",
    "timezone": "America/New_York"
  }
}
```

> Optional session config (`resources`, `vault_ids`, etc.) is supported the same way as on CreateSession. Response includes `status`, `paused_reason`, and `schedule.upcoming_runs_at` (next fire times). See `shared/managed-agents-scheduled-deployments.md`.

### SendEvents Request Body

```json
{
  "events": [
    {
      "type": "user.message",
      "content": [
        {
          "type": "text",
          "text": "Hello"
        }
      ]
    }
  ]
}
```

> `system.message` events (update the system prompt between turns) use the same envelope with `type: "system.message"` — Claude Opus 4.8 only; see `shared/managed-agents-events.md` § Updating the system prompt mid-session.

### Define Outcome Event

```json
{
  "type": "user.define_outcome",
  "description": "Build a DCF model for Costco in .xlsx",
  "rubric": { "type": "file", "file_id": "file_01..." },
  "max_iterations": 5
}
```

> `rubric` is required: `{type: "text", content}` or `{type: "file", file_id}`. `max_iterations` default 3, max 20. Echoed back with `outcome_id` + `processed_at`. See `shared/managed-agents-outcomes.md`.

### Tool Result Event

```json
{
  "type": "user.custom_tool_result",
  "custom_tool_use_id": "sevt_abc123",
  "content": [{ "type": "text", "text": "Result data" }],
  "is_error": false
}
```

---

## Error Handling

Managed Agents endpoints use the standard Anthropic API error format. Errors are returned with an HTTP status code and a JSON body containing `type`, `error`, and `request_id`:

```json
{
  "type": "error",
  "error": {
    "type": "invalid_request_error",
    "message": "Description of what went wrong"
  },
  "request_id": "req_011CRv1W3XQ8XpFikNYG7RnE"
}
```

Include the `request_id` when reporting issues to Anthropic — it lets us trace the request end-to-end. The inner `error.type` is one of the following:

| Status | Error type | Description |
|---|---|---|
| 400 | `invalid_request_error` | The request was malformed or missing required parameters |
| 401 | `authentication_error` | Invalid or missing API key |
| 403 | `permission_error` | The API key doesn't have permission for this operation |
| 404 | `not_found_error` | The requested resource doesn't exist |
| 409 | `invalid_request_error` | The request conflicts with the resource's current state (e.g., sending to an archived session) |
| 413 | `request_too_large` | The request body exceeds the maximum allowed size |
| 429 | `rate_limit_error` | Too many requests — check rate limit headers for retry timing |
| 500 | `api_error` | An internal server error occurred |
| 529 | `overloaded_error` | The service is temporarily overloaded — retry with backoff |

Note that `409 Conflict` carries `error.type: "invalid_request_error"` (there is no separate `conflict_error` type); inspect both the HTTP status and the `message` to distinguish conflicts from other invalid requests.

---

## Rate Limits

Managed Agents endpoints have per-organization request-per-minute (RPM) limits, separate from your [Messages API token limits](https://platform.claude.com/docs/en/api/rate-limits). Model inference inside a session still draws from your organization's standard ITPM/OTPM limits.

| Endpoint group | Scope | RPM | Max concurrent |
|---|---|---|---|
| Create operations (Agents, Sessions, Vaults) | organization | 300 | — |
| All other operations (Agents, Sessions, Vaults) | organization | 600 | — |
| All operations (Environments) | organization | 60 | 5 |

Files and Skills endpoints use the standard tier-based [rate limits](https://platform.claude.com/docs/en/api/rate-limits).

When a limit is exceeded the API returns `429` with a `rate_limit_error` (see [Error Handling](#error-handling) for the response envelope) and a `retry-after` header indicating how many seconds to wait before retrying. The Anthropic SDK reads this header and retries automatically.

FILE:shared/managed-agents-client-patterns.md
# Managed Agents — Common Client Patterns

Patterns you'll write on the client side when driving a Managed Agent session, grounded in working SDK examples.

Code samples are TypeScript — Python and cURL follow the same shape; see `python/managed-agents/README.md` and `curl/managed-agents.md` for equivalents.

---

## 1. Lossless stream reconnect

**Problem:** SSE has no replay. If the connection drops mid-session, a naive reconnect re-opens the stream from "now" and you silently miss every event emitted in between.

**Solution:** on reconnect, fetch the full event history via `events.list()` *before* consuming the live stream, and dedupe on event ID as the live stream catches up.

```ts
const seenEventIds = new Set<string>()
const stream = await client.beta.sessions.events.stream(session.id)

// Stream is now open and buffering server-side. Read history first.
for await (const event of client.beta.sessions.events.list(session.id)) {
  seenEventIds.add(event.id)
  handle(event)
}

// Tail the live stream. Dedupe only gates handle() — terminal checks must run
// even for already-seen events, or a terminal event that was in the history
// response gets skipped by `continue` and the loop never exits.
for await (const event of stream) {
  if (!seenEventIds.has(event.id)) {
    seenEventIds.add(event.id)
    handle(event)
  }
  if (event.type === 'session.status_terminated') break
  if (event.type === 'session.status_idle' && event.stop_reason.type !== 'requires_action') break
}
```

---

## 2. `processed_at` — queued vs processed

Every event on the stream carries `processed_at` (ISO 8601). For client-sent events (`user.message`, `user.interrupt`, `user.tool_confirmation`, `user.custom_tool_result`) it's `null` when the event has been queued but not yet picked up by the agent, and populated once the agent processes it. The same event appears on the stream twice — once with `processed_at: null`, once with a timestamp.

```ts
for await (const event of stream) {
  if (event.type === 'user.message') {
    if (event.processed_at == null) onQueued(event.id)
    else onProcessed(event.id, event.processed_at)
  }
}
```

Use this to drive pending → acknowledged UI state for anything you send. How you map a locally-rendered optimistic message to the server-assigned `event.id` is application-specific (typically via the return value of `events.send()` or FIFO ordering).

---

## 3. Interrupt a running session

Send `user.interrupt` as a normal event. The session keeps running until it reaches a safe boundary, then goes idle.

```ts
await client.beta.sessions.events.send(session.id, {
  events: [{ type: 'user.interrupt' }],
})

// Drain until the session is truly done — see Pattern 5 for the full gate.
for await (const event of stream) {
  if (event.type === 'session.status_terminated') break
  if (
    event.type === 'session.status_idle' &&
    event.stop_reason.type !== 'requires_action'
  ) break
}
```

Reference: `interrupt.ts` — sends the interrupt the moment it sees `span.model_request_start`, drains to idle, then verifies via `sessions.retrieve()`.

---

## 4. `tool_confirmation` round-trip

When the agent has `permission_policy: { type: 'always_ask' }`, any call to that tool fires an `agent.tool_use` event with `evaluated_permission === 'ask'` and the session goes idle waiting for a decision. Respond with `user.tool_confirmation`.

```ts
for await (const event of stream) {
  if (event.type === 'agent.tool_use' && event.evaluated_permission === 'ask') {
    await client.beta.sessions.events.send(session.id, {
      events: [{
        type: 'user.tool_confirmation',
        tool_use_id: event.id,         // not a toolu_ id — use event.id
        result: 'allow',               // or 'deny'
        // deny_message: '...',        // optional, only with result: 'deny'
      }],
    })
  }
}
```

Key points:
- `tool_use_id` is `event.id` (typically `sevt_...`), **not** a `toolu_...` ID.
- `result` is `'allow' | 'deny'`. Use `deny_message` to tell the model *why* you denied — it gets surfaced back to the agent.
- Multiple pending tools: respond once per `agent.tool_use` event with `evaluated_permission === 'ask'`.

Reference: `tool-permissions.ts`.

---

## 5. Correct idle-break gate

Do not break on `session.status_idle` alone. The session goes idle transiently — e.g. between parallel tool executions, while waiting for a `user.tool_confirmation`, or while awaiting a `user.custom_tool_result`. Break when idle with a terminal `stop_reason`, or on `session.status_terminated`.

```ts
for await (const event of stream) {
  handle(event)
  if (event.type === 'session.status_terminated') break
  if (event.type === 'session.status_idle') {
    if (event.stop_reason.type === 'requires_action') continue // waiting on you — handle it
    break // end_turn or retries_exhausted — both terminal
  }
}
```

`stop_reason.type` values on `session.status_idle`:
- `requires_action` — agent is waiting on a client-side event (tool confirmation, custom tool result). Handle it, don't break.
- `retries_exhausted` — terminal failure. Break, then check `sessions.retrieve()` for the error state.
- `end_turn` — normal completion.

---

## 6. Post-idle status-write race

The SSE stream emits `session.status_idle` slightly before the session's queryable status reflects it. Clients that break on idle and immediately call `sessions.delete()` or `sessions.archive()` will intermittently 400 with "cannot delete/archive while running."

Poll before cleanup:

```ts
let s
for (let i = 0; i < 10; i++) {
  s = await client.beta.sessions.retrieve(session.id)
  if (s.status !== 'running') break
  await new Promise(r => setTimeout(r, 200))
}
if (s?.status !== 'running') {
  await client.beta.sessions.archive(session.id)
} // else: still running after 2s — don't archive, let it settle or escalate
```

---

## 7. Stream-first, then send

Always open the stream **before** sending the kickoff event. Otherwise the agent may process the event and emit the first events before your consumer is attached, and you'll miss them.

```ts
const stream = await client.beta.sessions.events.stream(session.id)
await client.beta.sessions.events.send(session.id, {
  events: [{ type: 'user.message', content: [{ type: 'text', text: 'Hello' }] }],
})
for await (const event of stream) { /* ... */ }
```

The `Promise.all([stream, send])` shape works too, but stream-first is simpler and has the same effect — the stream starts buffering the moment it's opened.

---

## 8. File-mount gotchas

**The mounted resource has a different `file_id` than the file you uploaded.** Session creation makes a session-scoped copy.

```ts
const uploaded = await client.beta.files.upload({ file })
// uploaded.id         → the original file
const session = await client.beta.sessions.create({
  /* ... */
  resources: [{ type: 'file', file_id: uploaded.id, mount_path: '/workspace/data.csv' }],
})
// session.resources[0].file_id !== uploaded.id  ← different IDs
```

Delete the original via `files.delete(uploaded.id)`; the session-scoped copy is garbage-collected with the session. `mount_path` must be absolute — see `shared/managed-agents-environments.md`.

---

## 9. Secrets for non-MCP APIs and CLIs — keep them host-side via custom tools

**Problem:** you want the agent to call a third-party API or run a CLI that needs a secret (API key, token, service-account credential), but you can't or don't want to hand the secret to a vault.

**First check:** for cloud environments, the first-class answer is now a vault `environment_variable` credential — the agent's shell sees an opaque placeholder and the real secret is substituted at egress. See `shared/managed-agents-tools.md` → Vaults. Use this pattern instead when that doesn't fit: **self-hosted sandboxes** (env-var credentials not yet supported there), clients that reject the placeholder via local format validation, secrets that must never leave your infrastructure, or calls that need host-side binaries.

**Solution:** move the authenticated call to your side. Declare a custom tool on the agent; when the agent emits `agent.custom_tool_use`, your orchestrator (the process reading the SSE stream) executes the call with its own credentials and responds with `user.custom_tool_result`. The container never sees the key.

```ts
// Agent template: declare the tool, no credentials
tools: [{ type: 'custom', name: 'linear_graphql', input_schema: { /* query, vars */ } }]

// Orchestrator: handle the call with host-side creds
for await (const event of stream) {
  if (event.type === 'agent.custom_tool_use' && event.name === 'linear_graphql') {
    const result = await linear.request(event.input.query, event.input.vars) // host's key
    await client.beta.sessions.events.send(session.id, {
      events: [{ type: 'user.custom_tool_result', tool_use_id: event.id, result }],
    })
  }
}
```

Same shape works for `gh` CLI, local eval scripts, or anything else that needs host-side auth or binaries.

**Security note:** this does not expose a public endpoint. `agent.custom_tool_use` arrives on the SSE stream your orchestrator already holds open with your Anthropic API key, and `user.custom_tool_result` goes back via `events.send()` under the same key. Your orchestrator is a client, not a server — nothing unauthenticated is listening.

**Do not embed API keys in the system prompt or user messages as a workaround.** Prompts and messages are stored in the session's event history, returned by `events.list()`, and included in compaction summaries — a secret placed there is durably persisted and readable via the API for the life of the session.

FILE:shared/managed-agents-core.md
# Managed Agents — Core Concepts

## Architecture

Managed Agents is built around four core concepts:

| Concept | Endpoint | What it is |
|---|---|---|
| **Agent** | `/v1/agents` | A persisted, versioned object defining the agent's capabilities and persona: model, system prompt, tools, MCP servers, skills. **Must be created before starting a session.** See the Agents section below. |
| **Session** | `/v1/sessions` | A stateful interaction with an agent. References a pre-created agent by ID + an environment + initial instructions. Produces an event stream. |
| **Environment** | `/v1/environments` | A template defining the configuration for container provisioning. |
| **Container** | N/A | An isolated compute instance where the agent's **tools** execute (bash, file ops, code). The agent loop does not run here — it runs on Anthropic's orchestration layer and acts on the container via tool calls. |

```
                       ┌─────────────────────────────────────┐
                       │  Anthropic orchestration layer      │
Agent (config) ───────▶│  (agent loop: Claude + tool calls)  │
                       └──────────────┬──────────────────────┘
                                      │ tool calls
                                      ▼
Environment (template) ──▶ Container (tool execution workspace)
                                 │
                         Session ─┤
                                 ├── Resources (files, repos, memory stores — attached at startup)
                                 ├── Vault IDs (MCP credential references)
                                 └── Conversation (event stream in/out)
```

> **Agent creation is a prerequisite.** Sessions reference a pre-created agent by ID — `model`/`system`/`tools` live on the agent object, never on the session. Every flow starts with `POST /v1/agents`.

---

## Session Lifecycle

```
rescheduling → running ↔ idle → terminated
```

| Status         | Description                                                        |
| -------------- | ------------------------------------------------------------------ |
| `idle` | Agent has finished the current task, and is awaiting input. It's either waiting for input to continue working via a `user.message` or blocked awaiting a `user.custom_tool_result` or `user.tool_confirmation`. The `stop_reason` attached contains more information about why the Agent has stopped working. |
| `running` | Session has starting running, and the Agent is actively doing work. |
| `rescheduling` | Session is (re)scheduling after a retryable error has occurred, ready to be picked up by the orchestration system. |
| `terminated` | Session has terminated, entering an irreversible and unusable state.  |

- Events can be sent when the session is `running` or `idle`. Messages are queued and processed in order.
- The agent transitions `idle → running` when it receives a new event, then back to `idle` when done.
- Errors surface as `session.error` events in the stream, not as a status value.

### Built-in session features

- **Context compaction** — if you approach max context, the API automatically condenses session history to keep the interaction going
- **Prompt caching** — historical repeated tokens are cached, reducing processing time and cost
- **Extended thinking** — on by default, returned as `agent.thinking` events

### Session operations

| Operation | Notes |
|---|---|
| List / fetch | Paginated list or single resource by ID |
| Update | Only `title` is updatable |
| Archive | Session becomes **read-only**. Not reversible. |
| Delete | Permanently deletes session, event history, container, and checkpoints. |

These are ops/inspection calls — typically made from a terminal, not application code. From the shell (see `shared/anthropic-cli.md`):

```sh
ant beta:sessions list --transform '{id,title,status,created_at}' --format jsonl
ant beta:sessions retrieve --session-id "$SID"
ant beta:sessions:events stream --session-id "$SID"   # watch events live
ant beta:sessions archive  --session-id "$SID"
ant beta:sessions delete   --session-id "$SID"
```

---

## Sessions

A session is a running agent instance inside an environment.

### Session Object

Key fields returned by the API:

| Field           | Type     | Description                                         |
| --------------- | -------- | --------------------------------------------------- |
| `type` | string | Always `"session"` |
| `id` | string | Unique session ID |
| `title` | string | Human-readable title |
| `status` | string | `idle`, `running`, `rescheduling`, `terminated` |
| `created_at` | string | ISO 8601 timestamp |
| `updated_at` | string | ISO 8601 timestamp |
| `archived_at` | string | ISO 8601 timestamp (nullable) |
| `environment_id` | string | Environment ID |
| `agent` | object | Agent configuration |
| `resources` | array | Attached files, repos, and memory stores |
| `metadata` | object | User-provided key-value pairs (max 8 keys) |
| `usage` | object | Token usage statistics |

### Creating a session

**A session is meaningless without an agent.** Sessions reference a pre-created agent by ID. Create the agent first via `agents.create()`, then reference it:

```ts
// 1. Create the agent (reusable, versioned)
const agent = await client.beta.agents.create(
  {
    name: "Coding Assistant",
    model: "claude-opus-4-8",
    system: "You are a helpful coding agent.",
    tools: [{ type: "agent_toolset_20260401"}],
  },
);

// 2. Start a session that references it
const session = await client.beta.sessions.create(
  {
    agent: agent.id,  // string shorthand → latest version. Or: { type: "agent", id: agent.id, version: agent.version }
    environment_id: environmentId,
    title: "Hello World Session",
  },
);
```

> 💡 **Watch it live in Console.** While developing, print a link so you can click through to the session UI instead of parsing the event stream: `https://platform.claude.com/workspaces/{workspace}/sessions/{session.id}`. Use `default` for the workspace slug unless you created the session in a non-default workspace; the sessions list for your workspace is at `https://platform.claude.com/workspaces/default/sessions`. Include this `print`/`console.log` in code you generate for users who are iterating locally.

**Session creation parameters:**

| Field           | Type     | Required | Description                                    |
| --------------- | -------- | -------- | ---------------------------------------------- |
| `agent`         | string or object | **Yes** | String shorthand `"agent_abc123"` (latest version) or `{type: "agent", id, version}` |
| `environment_id`| string   | **Yes**  | Environment ID                                 |
| `title`         | string   | No       | Human-readable name (appears in logs/dashboards) |
| `resources`     | array    | No       | Files, GitHub repos, or memory stores, attached to the container at startup. Memory stores are session-create-only (not addable via `resources.add()`). |
| `vault_ids`     | array    | No       | Vault IDs (`vlt_*`) — MCP credentials with auto-refresh + `environment_variable` secrets substituted at egress. See `shared/managed-agents-tools.md` → Vaults. |
| `metadata`      | object   | No       | User-provided key-value pairs                  |

**Agent configuration fields** (passed to `agents.create()`, not `sessions.create()`):

| Field         | Type     | Required | Description                                    |
| ------------- | -------- | -------- | ---------------------------------------------- |
| `name`        | string   | **Yes**  | Human-readable name (1-256 chars)              |
| `model`       | string or object | **Yes** | Claude model ID (bare string, or `{id, speed}` object). All Claude 4.5+ models supported. |
| `system`      | string   | No       | System prompt — defines the agent's behavior (up to 100K chars) |
| `tools`       | array    | No       | Encompasses three kinds: (1) pre-built Claude Agent tools (`agent_toolset_20260401`), (2) MCP tools (`mcp_toolset`), and (3) custom client-side tools. Max 128. |
| `mcp_servers` | array    | No       | MCP server connections — standardized third-party capabilities (e.g. GitHub, Asana). Max 20, unique names. See `shared/managed-agents-tools.md` → MCP Servers. |
| `skills`      | array    | No       | Customized "best-practices" context with progressive disclosure. Max 20. See `shared/managed-agents-tools.md` → Skills. |
| `description` | string   | No       | Description of the agent (up to 2048 chars)    |
| `multiagent`  | object   | No       | `{type: "coordinator", agents: [...]}` — roster this agent may delegate to. See `shared/managed-agents-multiagent.md`. |
| `metadata`    | object   | No       | Arbitrary key-value pairs (max 16, keys ≤64 chars, values ≤512 chars) |

---

## Agents

**This is where every Managed Agents flow begins.** The agent object is a persisted, versioned configuration — you create it once, then reference it by ID every time you start a session. No agent → no session.

### Agent Object

The API is **flat** — `model`, `system`, `tools` etc. are top-level fields, not wrapped in an `agent:{}` sub-object.

| Field              | Type     | Required | Description                                        |
| ------------------ | -------- | -------- | -------------------------------------------------- |
| `name`             | string   | Yes      | Human-readable name                                |
| `model`            | string   | Yes      | Claude model ID                                    |
| `system`           | string   | No       | System prompt                                      |
| `tools`            | array    | No       | Agent toolset / MCP toolset / custom tools         |
| `mcp_servers`      | array    | No       | MCP server connections                             |
| `skills`           | array    | No       | Skill references (max 20)                          |
| `description`      | string   | No       | Description of the agent                           |
| `multiagent`       | object   | No       | Coordinator roster — see `shared/managed-agents-multiagent.md` |
| `metadata`         | object   | No       | Arbitrary key-value pairs                          |

### Lifecycle: create once, run many, update in place

The agent is a **persistent resource**, not a per-run parameter. The intended pattern:

```
┌─ setup (once) ─────────┐     ┌─ runtime (every invocation) ─┐
│ agents.create()        │     │ sessions.create(             │
│   → store agent_id     │ ──→ │   agent={type:..., id: ID}   │
│     in config/env/db   │     │ )                            │
└────────────────────────┘     └──────────────────────────────┘
```

**Anti-pattern:** calling `agents.create()` at the top of every script run. This accumulates orphaned agent objects, pays create latency on every invocation, and defeats the versioning model. If you see `agents.create()` in a function that's called per-request or per-cron-tick, that's wrong — hoist it to one-time setup and persist the ID.

> **Recommended — define agents and environments as YAML + apply via the `ant` CLI.** The split is **CLI for the control plane, SDK for the data plane**: agents and environments are relatively static resources you manage with `ant` (version-controlled YAML, applied from CI); sessions are dynamic and driven by your application through the SDK. See `shared/anthropic-cli.md` → *Version-controlled Managed Agents resources* for the `ant beta:agents create < agent.yaml` / `update --version N` flow. The SDK `agents.create()` call shown elsewhere in this doc is the in-code equivalent — use it when you need to provision programmatically, but prefer the YAML flow for anything a human maintains.

### Versioning

Each `POST /v1/agents/{id}` (update) creates a new immutable version (numeric timestamp, e.g. `1772585501101368014`). The agent's history is append-only — you can't edit a past version.

**Why version:**
- **Reproducibility** — pin a session to a known-good config: `{type: "agent", id, version: 3}`
- **Safe iteration** — update the agent without breaking sessions already running on the old version
- **Rollback** — if a new system prompt regresses, pin new sessions back to the prior version while you debug

**`version` is optional.** Omit it (or use the string shorthand `agent="agent_abc123"`) to get the latest version at session-creation time. Pass it explicitly (`{type: "agent", id, version: N}`) to pin for reproducibility.

**Getting the version to pin:** `agents.create()` and `agents.update()` both return `version` in the response. Store it alongside `agent_id`. To fetch the current latest for an existing agent: `GET /v1/agents/{id}` → `.version`.

**When to update vs create new:** Update (`POST /v1/agents/{id}`) when it's conceptually the same agent with tweaked behavior (better prompt, extra tool). Create a new agent when it's a different persona/purpose. Rule of thumb: if you'd give it the same `name`, update.

### Agent Endpoints

| Operation        | Method   | Path                                  |
| ---------------- | -------- | ------------------------------------- |
| Create           | `POST`   | `/v1/agents`                          |
| List             | `GET`    | `/v1/agents`                          |
| Get              | `GET`    | `/v1/agents/{id}`                     |
| Update           | `POST`   | `/v1/agents/{id}`                     |
| Archive          | `POST`   | `/v1/agents/{id}/archive`             |

> ⚠️ **Archive is permanent.** Archiving makes the agent read-only: existing sessions continue to run, but **new sessions cannot reference it**, and there is no unarchive. Since agents have no `delete`, this is the terminal lifecycle state. Never archive a production agent as routine cleanup — confirm with the user first.

### Using an Agent in a Session

Reference the agent by string ID (latest version) or by object with an explicit version:

```python
# String shorthand — uses the agent's latest version
session = client.beta.sessions.create(
    agent=agent.id,
    environment_id=environment_id,
)

# Or pin to a specific version (int)
session = client.beta.sessions.create(
    agent={"type": "agent", "id": agent.id, "version": agent.version},
    environment_id=environment_id,
)
```

### Updating the agent configuration mid-session

`sessions.update()` can change `agent.tools`, `agent.mcp_servers` (including permission policies), and `vault_ids` on an **existing** session. This is a **session-local override** — it does not create a new agent version and does not propagate back to the agent object. The provided arrays are **full replacements**; to append one tool, `GET` the session, modify, and `POST` back. The session must be `idle` — interrupt first if running.

```python
client.beta.sessions.update(
    session.id,
    agent={
        "tools": [
            {"type": "agent_toolset_20260401"},
            {"type": "mcp_toolset", "mcp_server_name": "linear"},
        ],
        "mcp_servers": [{"type": "url", "name": "linear", "url": "https://mcp.linear.app/sse"}],
    },
    vault_ids=["vlt_..."],
)
```


FILE:shared/managed-agents-environments.md
# Managed Agents — Environments & Resources

## Environments

Creating a session requires an `environment_id`. Environments are **reusable configuration templates** for spinning up containers in Anthropic's infrastructure — you might create different environments for different use cases (e.g. data visualization vs web development, with different package sets). Anthropic handles scaling, container lifecycle, and work orchestration.

**Environment names must be unique.** Creating an environment with an existing name returns 409.

### Networking

| Network Policy   | Description                                                   |
| ---------------- | ------------------------------------------------------------- |
| `unrestricted`   | Full egress (except legal blocklist)                          |
| `limited`        | Deny-by-default; opt in via `allowed_hosts` / `allow_package_managers` / `allow_mcp_servers` |

```json
{
  "networking": {
    "type": "limited",
    "allow_package_managers": true,
    "allow_mcp_servers": true,
    "allowed_hosts": ["api.example.com"]
  }
}
```

All three `limited` fields are optional. `allow_package_managers` (default `false`) permits PyPI/npm/etc.; `allow_mcp_servers` (default `false`) permits the agent's configured MCP server endpoints without listing them in `allowed_hosts`.

**MCP caveat:** Under `limited` networking, either set `allow_mcp_servers: true` or add each MCP server domain to `allowed_hosts`. Otherwise the container can't reach them and tools silently fail.

### Creating an environment

The SDK adds `managed-agents-2026-04-01` automatically. TypeScript:

```ts
const env = await client.beta.environments.create({
  name: "my_env",
  config: {
    type: "cloud",
    networking: { type: "unrestricted" },
  },
});
```

### Self-hosted sandboxes

To run tool execution in **your own infrastructure** instead of Anthropic's, set `config: {type: "self_hosted"}` — the agent loop stays on Anthropic's side, but `bash` / file ops / code execute in a container you control via an outbound-polling worker. The `networking` block does not apply (you control egress). Resource mounting (`file`, `github_repository`) and memory stores behave differently — see `shared/managed-agents-self-hosted-sandboxes.md` for the worker, credentials, and cloud-vs-self-hosted comparison.

### Environment CRUD

| Operation        | Method   | Path                                       | Notes |
| ---------------- | -------- | ------------------------------------------ | ----- |
| Create           | `POST`   | `/v1/environments`                         | |
| List             | `GET`    | `/v1/environments`                         | Paginated (`limit`, `after_id`, `before_id`) |
| Get              | `GET`    | `/v1/environments/{id}`                    | |
| Update           | `POST`   | `/v1/environments/{id}`                    | Changes apply only to **new** containers; existing sessions keep their original config |
| Delete           | `DELETE` | `/v1/environments/{id}`                    | Returns 204. |
| Archive          | `POST`   | `/v1/environments/{id}/archive`            | Makes it **read-only**; existing sessions continue, new sessions cannot reference it. No unarchive — terminal state. |

---

## Resources

Attach files, GitHub repositories, and memory stores to a session. **Session creation blocks until all resources are mounted** — the container won't go `running` until every file and repo is in place. Max **999 file resources** per session. Multiple GitHub repositories per session are supported. For `type: "memory_store"` resources (persistent cross-session memory — max 8 per session), see `shared/managed-agents-memory.md`.

### File Uploads (input — host → agent)

Upload a file first via the Files API, then reference by `file_id` + `mount_path`:

```ts
// 1. Upload
const file = await client.beta.files.upload({
  file: fs.createReadStream("data.csv"),
});

// 2. Attach as a session resource
const session = await client.beta.sessions.create({
  agent: agent.id,
  environment_id: envId,
  resources: [
    { type: "file", file_id: file.id, mount_path: "/workspace/data.csv" }
  ],
});
```

**`mount_path` is required** and must be absolute. Parent directories are created automatically. Agent working directory defaults to `/workspace`. Files are mounted read-only — the agent writes modified versions to new paths.

### Session outputs (output — agent → host)

The agent can write files to `/mnt/session/outputs/` during a session. These are automatically captured by the Files API and can be listed and downloaded afterwards:

```ts
// After the turn completes, list output files scoped to this session:
for await (const f of client.beta.files.list({
  scope_id: session.id,
  betas: ["managed-agents-2026-04-01"],
})) {
  console.log(f.filename, f.size_bytes);
  const resp = await client.beta.files.download(f.id);
  const text = await resp.text();
}
```

**Requirements:**
- The `write` tool (or `bash`) must be enabled for the agent to create output files.
- Session-scoped `files.list` / `files.download` captures outputs written to `/mnt/session/outputs/`.
- The filter parameter is **`scope_id`** (REST query param `?scope_id=<session_id>`). The SDK's files resource auto-adds only the `files-api-2025-04-14` header, so pass `betas: ["managed-agents-2026-04-01"]` explicitly (or both headers on raw HTTP) — without it the API may reject `scope_id` as an unknown field. Requires `@anthropic-ai/sdk` ≥ 0.88.0 / `anthropic` (Python) ≥ 0.92.0 — older versions don't type `scope_id`. The `ant` CLI does **not** expose this flag yet; use the SDK or curl.
- Pass the session ID returned by `sessions.create()` verbatim (e.g. `sesn_011CZx...`) — the API validates the prefix.
- There's a brief indexing lag (~1–3s) between `session.status_idle` and output files appearing in `files.list`. Retry once or twice if empty.

> **Fallback when `scope_id` filtering is unavailable** (older SDK, or endpoint returns an error): send a follow-up `user.message` asking the agent to `read` each file under `/mnt/session/outputs/` and return the contents. The agent streams the file bodies back as `agent.message` text. This works for text files only and costs output tokens — use it to unblock, not as the primary path.

This gives you a bidirectional file bridge: upload reference data in, download agent artifacts out.

### GitHub Repositories

Clones a GitHub repository into the session container during initialization, before the agent begins execution. The agent can read, edit, commit, and push via `bash` (`git`). Multiple repositories per session are supported — add one `resources` entry per repo. Repositories are cached, so future sessions that use the same repository start faster.

Repositories are attached for the lifetime of the session — to change which repositories are mounted, create a new session. You **can** rotate a repository's `authorization_token` on a running session via `client.beta.sessions.resources.update(resource_id, {session_id, authorization_token})`; the resource `id` is returned at session creation and by `resources.list()`.

**Fields:**

| Field | Required | Notes |
|---|---|---|
| `type` | ✅ | `"github_repository"` |
| `url` | ✅ | The GitHub repository URL |
| `authorization_token` | ✅ | GitHub Personal Access Token with repository access. **Never echoed in API responses.** |
| `mount_path` | ❌ | Path where the repository will be cloned. Defaults to `/workspace/<repo-name>`. |
| `checkout` | ❌ | `{type: "branch", name: "..."}` or `{type: "commit", sha: "..."}`. Defaults to the repo's default branch. |

**Token permission levels** (fine-grained PATs):
- `Contents: Read` — clone only
- `Contents: Read and write` — push changes and create pull requests

**How auth works:** `authorization_token` is never placed inside the container. `git pull` / `git push` and GitHub REST calls against the attached repository are routed through an Anthropic-side git proxy that injects the token after the request leaves the sandbox. Code running in the container — including anything the agent writes — cannot read or exfiltrate it.

> ‼️ **To generate pull requests** you also need GitHub **MCP server** access — the `github_repository` resource gives filesystem + git access only. See `shared/managed-agents-tools.md` → MCP Servers. The PR workflow is: edit files in the mounted repo → push branch via `bash` (authenticated via the git proxy using `authorization_token`) → create PR via the MCP `create_pull_request` tool (authenticated via the vault).

**TypeScript:**

```ts
// 1. Create the agent — declare GitHub MCP (no auth here)
const agent = await client.beta.agents.create(
  {
    name: 'GitHub Agent',
    model: 'claude-opus-4-8',
    mcp_servers: [
      { type: 'url', name: 'github', url: 'https://api.githubcopilot.com/mcp/' },
    ],
    tools: [
      { type: 'agent_toolset_20260401', default_config: { enabled: true } },
      { type: 'mcp_toolset', mcp_server_name: 'github' },
    ],
  },
);

// 2. Start a session — attach vault for MCP auth + mount the repo
const session = await client.beta.sessions.create({
  agent: agent.id,
  environment_id: envId,
  vault_ids: [vaultId],  // vault contains the GitHub MCP OAuth credential
  resources: [
    {
      type: 'github_repository',
      url: 'https://github.com/owner/repo',
      authorization_token: process.env.GITHUB_TOKEN,  // repo clone token (≠ MCP auth)
      checkout: { type: 'branch', name: 'main' },
    },
  ],
});
```

**Python:**

```python
import os

agent = client.beta.agents.create(
    name="GitHub Agent",
    model="claude-opus-4-8",
    mcp_servers=[{
        "type": "url",
        "name": "github",
        "url": "https://api.githubcopilot.com/mcp/",
    }],
    tools=[
        {"type": "agent_toolset_20260401", "default_config": {"enabled": True}},
        {"type": "mcp_toolset", "mcp_server_name": "github"},
    ],
)

session = client.beta.sessions.create(
    agent=agent.id,
    environment_id=env_id,
    vault_ids=[vault_id],  # vault contains the GitHub MCP OAuth credential
    resources=[{
        "type": "github_repository",
        "url": "https://github.com/owner/repo",
        "authorization_token": os.environ["GITHUB_TOKEN"],  # repo clone token (≠ MCP auth)
        "checkout": {"type": "branch", "name": "main"},
    }],
)
```

---

## Files API

Upload and manage files for use as session resources, and download files the agent wrote to `/mnt/session/outputs/`.

| Operation        | Method   | Path                                  | SDK |
| ---------------- | -------- | ------------------------------------- | --- |
| Upload           | `POST`   | `/v1/files`                           | `client.beta.files.upload({ file })` |
| List             | `GET`    | `/v1/files?scope_id=...`              | `client.beta.files.list({ scope_id, betas: ["managed-agents-2026-04-01"] })` |
| Get Metadata     | `GET`    | `/v1/files/{id}`                      | `client.beta.files.retrieveMetadata(id)` |
| Download         | `GET`    | `/v1/files/{id}/content`              | `client.beta.files.download(id)` → `Response` |
| Delete           | `DELETE` | `/v1/files/{id}`                      | `client.beta.files.delete(id)` |

The `scope_id` filter on List scopes the results to files written to `/mnt/session/outputs/` by that session. Without the filter, you get all files uploaded to your account.

FILE:shared/managed-agents-events.md
# Managed Agents — Events & Steering

## Events

### Sending Events

Send events to a session via `POST /v1/sessions/{id}/events`.

| Event Type                | When to Send                                        |
| ------------------------- | --------------------------------------------------- |
| `user.message`            | Send a user message |
| `user.interrupt`          | Interrupt the agent while it's running |
| `user.tool_confirmation`  | Approve/deny a tool call (when `always_ask` policy) |
| `user.custom_tool_result` | Provide result for a custom tool call |
| `user.define_outcome`     | Start a rubric-graded iterate loop — see `shared/managed-agents-outcomes.md` |
| `system.message`          | Update the agent's system prompt between turns — **Claude Opus 4.8 only**; see § Updating the system prompt mid-session |

#### Updating the system prompt mid-session (`system.message`)

Unlike the `system` field on the agent definition (fixed at session creation), a `system.message` event changes the system prompt **as the session progresses** — a different persona, revised constraints, or runtime-fetched context that should shape behavior going forward:

```python
client.beta.sessions.events.send(
    session.id,
    events=[
        {
            "type": "system.message",
            "content": [
                {"type": "text", "text": "The user's current timezone is America/New_York."},
            ],
        },
    ],
)
```

Constraints:

- **Claude Opus 4.8 only.** If any model configured on the agent does not support mid-conversation system injection, the event is rejected with a `model_does_not_support_mid_conversation_system` validation error.
- **Cannot be sent while the session is idle with `stop_reason: requires_action`** (blocked on `user.custom_tool_result` / `user.tool_confirmation`).
- `content` accepts 1–1000 text items.

### Receiving Events

Three methods:

1. **Streaming (SSE)**: `GET /v1/sessions/{id}/events/stream` — real-time Server-Sent Events. **Long-lived** — the server sends periodic heartbeats to keep the connection alive.
2. **Polling**: `GET /v1/sessions/{id}/events` — paginated event list (query params: `limit` default 1000, `page`). **Returns immediately** — this is a plain paginated GET, not a long-poll.
3. **Webhooks**: Anthropic POSTs session state transitions to your HTTPS endpoint — thin payloads (IDs only), HMAC-signed, Console-registered. See `shared/managed-agents-webhooks.md`.

All received events carry `id`, `type`, and `processed_at` (ISO 8601; `null` if not yet processed by the agent).

> ⚠️ **Robust polling (raw HTTP).** If you bypass the SDK and roll your own poll loop, don't rely on `requests` or `httpx` timeouts as wall-clock caps — they're **per-chunk** read timeouts, reset every time a byte arrives. A trickling response (heartbeats, a wedged chunked-encoding body, a misbehaving proxy) can keep the call blocked indefinitely even with `timeout=(5, 60)` or `httpx.Timeout(120)`. Neither library has a "total wall-clock" timeout built in. For a hard deadline: track `time.monotonic()` at the loop level and break/cancel if a single request exceeds your budget (e.g. via a watchdog thread, or `asyncio.wait_for()` around async httpx). **Prefer the SDK** — `client.beta.sessions.events.stream()` and `client.beta.sessions.events.list()` handle timeout + retry sanely.
>
> If `GET /v1/sessions/{id}/events` (paginated) ever hangs after headers, you've likely hit `GET /v1/sessions/{id}/events` by mistake or a server-side stall — report it; don't treat it as a client-config problem.

### Event Types (Received)

Event types use dot notation, grouped by namespace:

| Event Type | Description |
| --- | --- |
| `agent.message` | Agent text output |
| `agent.thinking` | Extended thinking blocks |
| `agent.tool_use` | Agent used a built-in tool (`agent_toolset_20260401`) |
| `agent.tool_result` | Result from a built-in tool |
| `agent.mcp_tool_use` | Agent used an MCP tool |
| `agent.mcp_tool_result` | Result from an MCP tool |
| `agent.custom_tool_use` | Agent invoked a custom tool — session goes idle, you respond with `user.custom_tool_result` |
| `agent.thread_context_compacted` | Conversation context was compacted |
| `session.status_idle` | Agent has finished the current task, and is awaiting input. It's either waiting for input to continue working via a `user.message` or blocked awaiting a `user.custom_tool_result` or `user.tool_confirmation`. The `stop_reason` attached contains more information about why the Agent has stopped working. |
| `session.status_running` | Session has starting running, and the Agent is actively doing work. |
| `session.status_rescheduled` | Session is (re)scheduling after a retryable error has occurred, ready to be picked up by the orchestration system. |
| `session.status_terminated` | Session has terminated, entering an irreversible and unusable state.  |
| `session.error` | Error occurred during processing |
| `span.model_request_start` | Model inference started |
| `span.model_request_end` | Model inference completed |
| `span.outcome_evaluation_start` / `_ongoing` / `_end` | Grader progress for outcome-oriented sessions — see `shared/managed-agents-outcomes.md` |
| `session.thread_created` | Subagent thread spawned (multiagent) — see `shared/managed-agents-multiagent.md` |
| `session.thread_status_running` / `_idle` / `_rescheduled` / `_terminated` | Subagent thread status transitions (multiagent). `_idle` carries `stop_reason`. |
| `agent.thread_message_sent` / `_received` | Cross-thread message, carries `to_session_thread_id` / `from_session_thread_id` (multiagent) |

The stream also echoes back user-sent events (`user.message`, `user.interrupt`, `user.tool_confirmation`, `user.custom_tool_result`, `user.define_outcome`).

---

## Steering Patterns

Practical patterns for driving a session via the events surface.

### Stream-first ordering

**Open the stream before sending events.** The stream only delivers events that occur *after* it's opened — it does not replay current state or historical events. If you send a message first and open the stream second, early events (including fast status transitions) arrive buffered in a single batch and you lose the ability to react to them in real time.

```ts
// ✅ Correct — stream and send concurrently
const [response] = await Promise.all([
  streamEvents(sessionId),   // opens SSE connection
  sendMessage(sessionId, text),
]);

// ❌ Wrong — events before stream opens arrive as a single buffered batch
await sendMessage(sessionId, text);
const response = await streamEvents(sessionId);
```

**For full history,** use `GET /v1/sessions/{id}/events` (paginated list) — the stream only gives you live events from connection onward.

### Reconnecting after a dropped stream

**The SSE stream has no replay.** If your connection drops (httpx read timeout, network blip) and you reconnect, you only get events emitted *after* reconnection. Any events emitted during the gap are lost from the stream.

**The consolidation pattern:** on every (re)connect, overlap the stream with a history fetch and dedupe by event ID:

```python
def connect_with_consolidation(client, session_id):
    # 1. Open the SSE stream first
    stream = client.beta.sessions.events.stream(session_id=session_id)

    # 2. Fetch history to cover any gap
    history = client.beta.sessions.events.list(
        session_id=session_id,
    )

    # 3. Yield history first, then stream — dedupe by event.id
    seen = set()
    for ev in history.data:
        seen.add(ev.id)
        yield ev
    for ev in stream:
        if ev.id not in seen:
            seen.add(ev.id)
            yield ev
```

### Message queuing

**You don't have to wait for a response before sending the next message.** User events are queued server-side and processed in order. This is useful for chat bridges where the user sends rapid follow-ups:

```ts
// All three go into one session; agent processes them in order
await sendMessage(sessionId, "Summarize the README");
await sendMessage(sessionId, "Actually also check the CONTRIBUTING guide");
await sendMessage(sessionId, "And compare the two");
// Stream once — agent responds to all three as a coherent turn
```

Events can be sent up to the Session at any time. There is no need to wait on a specific session status to enqueue new events via `client.beta.sessions.events.send()`

### Interrupt

An `interrupt` event **jumps the queue** (ahead of any pending user messages) and forces the session into `idle`. Use this for "stop" / "nevermind" / "cancel" commands:

```ts
await client.beta.sessions.events.send(sessionId, {
  events: [{ type: 'interrupt' }],
});
```

The agent stops mid-task. It does not see the interrupt as a message — it just halts. Send a follow-up `user` event to explain what to do instead. If an outcome is active, the interrupt also marks `span.outcome_evaluation_end.result: "interrupted"` (see `shared/managed-agents-outcomes.md`).

> **Note**: Interrupt events may have empty IDs in the current implementation. When troubleshooting, use the `processed_at` timestamp along with surrounding event IDs.

### Event payloads

some events carry useful metadata beyond the status change itself:

`session.status_idle` — includes a `stop_reason` field which elaborates on why the session stopped and what type of further action is required by the user.
```json
{
  "id": "sevt_456",
  "processed_at": "2026-04-07T04:27:43.197Z",
  "stop_reason": {
    "event_ids": [
      "sevt_123"
    ],
    "type": "requires_action"
  },
  "type": "status_idle"
}
```

`span.model_request_end` contains a `model_usage` field for cost tracking and efficiency analysis:

```json
{
  "type": "span.model_request_end",
  "id": "sevt_456",
  "is_error": false,
  "model_request_start_id": "sevt_123",
  "model_usage": {
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 6656,
    "input_tokens": 3571,
    "output_tokens": 727
  },
  "processed_at": "2026-04-07T04:11:32.189Z"
}
```

**`agent.thread_context_compacted`** — emitted when the conversation history was summarized to fit context. Includes `pre_compaction_tokens` so you know how much was squeezed:

```json
{
  "id": "sevt_abc123",
  "processed_at": "2026-03-24T14:05:15.787Z",
  "type": "agent.thread_context_compacted"
}
```

### Archive

When done with a session, archive it to free resources:

```ts
await client.beta.sessions.archive(sessionId);
```

> Archiving a **session** is routine cleanup — sessions are per-run and disposable. **Do not generalize this to agents or environments**: those are persistent, reusable resources, and archiving them is permanent (no unarchive; new sessions cannot reference them). See `shared/managed-agents-overview.md` → Common Pitfalls.



FILE:shared/managed-agents-memory.md
# Managed Agents — Memory Stores

> **Public beta.** Memory stores ship under the `managed-agents-2026-04-01` beta header; the SDK sets it automatically on all `client.beta.memory_stores.*` calls. If `client.beta.memory_stores` is missing, upgrade to the latest SDK release.

Sessions are ephemeral by default — when one ends, anything the agent learned is gone. A **memory store** is a workspace-scoped collection of small text documents that persists across sessions. When a store is attached to a session (via `resources[]`), it is mounted into the container as a filesystem directory; the agent reads and writes it with the ordinary file tools, and a system-prompt note tells it the mount is there.

Every mutation to a memory produces an immutable **memory version** (`memver_...`), giving you an audit trail and point-in-time rollback/redact.

## Object model

| Object | ID prefix | Scope | Notes |
| --- | --- | --- | --- |
| Memory store | `memstore_...` | Workspace | Attach to sessions via `resources[]` |
| Memory | `mem_...` | Store | One text file, addressed by `path` (≤ 100KB each — prefer many small files) |
| Memory version | `memver_...` | Memory | Immutable snapshot per mutation; `operation` ∈ `created` / `modified` / `deleted` |

## Create a store

`description` is passed to the agent so it knows what the store contains — write it for the model, not for humans.

```python
store = client.beta.memory_stores.create(
    name="User Preferences",
    description="Per-user preferences and project context.",
)
print(store.id)  # memstore_01Hx...
```

Other SDKs: TypeScript `client.beta.memoryStores.create({...})`; Go `client.Beta.MemoryStores.New(ctx, ...)`. See `shared/managed-agents-api-reference.md` → SDK Method Reference for the full per-language table.

Stores support `retrieve` / `update` / `list` (with `include_archived`, `created_at_{gte,lte}` filters) / `delete` / **`archive`**. Archive makes the store read-only — existing session attachments continue, new sessions cannot reference it; no unarchive.

### Seed with content (optional)

Pre-load reference material before any session runs. `memories.create` creates a memory at the given `path`; if a memory already exists there the call returns `409` (`memory_path_conflict_error`, with the `conflicting_memory_id`). The store ID is the first positional argument.

```python
client.beta.memory_stores.memories.create(
    store.id,
    path="/formatting_standards.md",
    content="All reports use GAAP formatting. Dates are ISO-8601...",
)
```

## Attach to a session

Memory stores go in the session's `resources[]` array alongside `file` and `github_repository` resources (see `shared/managed-agents-environments.md` → Resources). Memory stores attach at **session create time only** — `sessions.resources.add()` does not accept `memory_store`.

```python
session = client.beta.sessions.create(
    agent=agent.id,
    environment_id=environment.id,
    resources=[
        {
            "type": "memory_store",
            "memory_store_id": store.id,
            "access": "read_write",  # or "read_only"; default is "read_write"
            "instructions": "User preferences and project context. Check before starting any task.",
        }
    ],
)
```

| Field | Required | Notes |
| --- | --- | --- |
| `type` | ✅ | `"memory_store"` |
| `memory_store_id` | ✅ | `memstore_...` |
| `access` | — | `"read_write"` (default) or `"read_only"` — enforced at the filesystem level on the mount |
| `instructions` | — | Session-specific guidance for this store, in addition to the store's `name`/`description`. ≤ 4,096 chars. |

**Max 8 memory stores per session.** Attach multiple when different slices of memory have different owners or lifecycles — e.g. one read-only shared-reference store plus one read-write per-user store, or one store per end-user/team/project sharing a single agent config.

### How the agent sees it (FUSE mount)

Each attached store is mounted in the session container at `/mnt/memory/<store-name>/`. The agent interacts with it using the standard file tools (`bash`, `read`, `write`, `edit`, `glob`, `grep`) — there are no dedicated memory tools. `access: "read_only"` makes the mount read-only at the filesystem level; `"read_write"` allows the agent to create, edit, and delete files under it. A short description of each mount (name, path, `instructions`, access) is automatically injected into the system prompt so the agent knows the store exists without you having to mention it.

Writes the agent makes under the mount are persisted back to the store and produce memory versions just like host-side `memories.update` calls.

## Manage memories directly (host-side)

Use these for review workflows, correcting bad memories, or seeding stores out-of-band.

### List

Returns `Memory | MemoryPrefix` entries — a `MemoryPrefix` (`type: "memory_prefix"`, just a `path`) is a directory-like node when listing hierarchically. Use `path_prefix` to scope (include a trailing slash: `"/notes/"` matches `/notes/a.md` but not `/notes_backup/old.md`) and `depth` to bound the tree walk. `order_by` / `order` sort the result. Pass `view="full"` to include `content` in each item; the default `"basic"` returns metadata only.

```python
for m in client.beta.memory_stores.memories.list(store.id, path_prefix="/"):
    if m.type == "memory":
        print(f"{m.path}  ({m.content_size_bytes} bytes, sha={m.content_sha256[:8]})")
    else:  # "memory_prefix"
        print(f"{m.path}/")
```

### Read

```python
mem = client.beta.memory_stores.memories.retrieve(memory_id, memory_store_id=store.id)
print(mem.content)
```

`retrieve` defaults to `view="full"` (content included); `view` matters mainly on list endpoints.

### Create vs. update

| Operation | Addressed by | Semantics |
| --- | --- | --- |
| `memories.create(store_id, path=..., content=...)` | **Path** | Create at `path`. `409` (`memory_path_conflict_error`, includes `conflicting_memory_id`) if the path is already occupied. |
| `memories.update(mem_id, memory_store_id=..., path=..., content=...)` | **`mem_...` ID** | Mutate existing memory. Change `content`, `path` (rename), or both. Renaming onto an occupied path returns the same `409 memory_path_conflict_error`. |

```python
mem = client.beta.memory_stores.memories.create(
    store.id,
    path="/preferences/formatting.md",
    content="Always use tabs, not spaces.",
)

client.beta.memory_stores.memories.update(
    mem.id,
    memory_store_id=store.id,
    path="/archive/2026_q1_formatting.md",  # rename
)
```

### Optimistic concurrency (precondition on `update`)

`memories.update` accepts a `precondition` so you can read → modify → write back without clobbering a concurrent writer. The only supported type is `content_sha256`. On mismatch the API returns `409` (`memory_precondition_failed_error`) — re-read and retry against fresh state.

```python
client.beta.memory_stores.memories.update(
    mem.id,
    memory_store_id=store.id,
    content="CORRECTED: Always use 2-space indentation.",
    precondition={"type": "content_sha256", "content_sha256": mem.content_sha256},
)
```

### Delete

```python
client.beta.memory_stores.memories.delete(mem.id, memory_store_id=store.id)
```

Pass `expected_content_sha256` for a conditional delete.

## Audit and rollback — memory versions

Every mutation creates an immutable `memver_...` snapshot. Versions accumulate for the lifetime of the parent memory; `memories.retrieve` always returns the current head, the version endpoints give you history.

| Operation that triggers it | `operation` field on the version |
| --- | --- |
| `memories.create` at a new path | `"created"` |
| `memories.update` changing `content`, `path`, or both (or an agent-side write to the mount) | `"modified"` |
| `memories.delete` | `"deleted"` |

Each version also records `created_by` — an actor object with `type` ∈ `session_actor` / `api_actor` / `user_actor` — and, after redaction, `redacted_at` + `redacted_by`.

### List versions

Newest-first, paginated. Filter by `memory_id`, `operation`, `session_id`, `api_key_id`, or `created_at_gte` / `created_at_lte`. Pass `view="full"` to include `content`; default is metadata-only.

```python
for v in client.beta.memory_stores.memory_versions.list(store.id, memory_id=mem.id):
    print(f"{v.id}: {v.operation}")
```

### Retrieve a version

```python
version = client.beta.memory_stores.memory_versions.retrieve(
    version_id, memory_store_id=store.id
)
print(version.content)
```

### Redact a version

Scrubs content from a historical version while preserving the audit trail (actor + timestamps). Clears `content`, `content_sha256`, `content_size_bytes`, and `path`; everything else stays. Use for leaked secrets, PII, or user-deletion requests.

```python
client.beta.memory_stores.memory_versions.redact(version_id, memory_store_id=store.id)
```

## Endpoint reference

See `shared/managed-agents-api-reference.md` → Memory Stores / Memories / Memory Versions for the full HTTP method/path tables. Raw HTTP base path:

```
POST   /v1/memory_stores
POST   /v1/memory_stores/{memory_store_id}/archive
GET    /v1/memory_stores/{memory_store_id}/memories
PATCH  /v1/memory_stores/{memory_store_id}/memories/{memory_id}
GET    /v1/memory_stores/{memory_store_id}/memory_versions
POST   /v1/memory_stores/{memory_store_id}/memory_versions/{version_id}/redact
```

For cURL examples and the CLI (`ant beta:memory-stores ...`), WebFetch the Memory URL in `shared/live-sources.md` → Managed Agents.

FILE:shared/managed-agents-multiagent.md
# Managed Agents — Multiagent Sessions

A coordinator agent can delegate to other agents within one session. All agents **share the container and filesystem**; each runs in its own **thread** — a context-isolated event stream with its own conversation history, model, system prompt, tools, MCP servers, and skills (from that agent's own config). Threads are persistent: the coordinator can send a follow-up to a subagent it called earlier and that subagent retains its prior turns.

The SDK sets the `managed-agents-2026-04-01` beta header automatically on all `client.beta.{agents,sessions}.*` calls; no additional header is required for multiagent.

---

## Declare the roster on the coordinator

`multiagent` is a **top-level field** on `agents.create()` / `agents.update()` — **not** a `tools[]` entry. `agents` lists 1–20 roster entries. Nothing changes on `sessions.create()` — the roster is resolved from the coordinator's config.

```python
orchestrator = client.beta.agents.create(
    name="Engineering Lead",
    model="claude-opus-4-8",
    system="You coordinate engineering work. Delegate code review to the reviewer and test writing to the test agent.",
    tools=[{"type": "agent_toolset_20260401"}],
    multiagent={
        "type": "coordinator",
        "agents": [
            reviewer.id,                                            # bare string — latest version
            {"type": "agent", "id": test_writer.id, "version": 4},  # pinned version
            {"type": "self"},                                       # the coordinator itself
        ],
    },
)

session = client.beta.sessions.create(agent=orchestrator.id, environment_id=env.id)
```

| Roster entry | Shape | Notes |
|---|---|---|
| String shorthand | `"agent_abc123"` | References the latest version of a stored agent. |
| Agent reference | `{type: "agent", id, version?}` | Omit `version` to pin the latest at coordinator save time. |
| Self | `{type: "self"}` | The coordinator can spawn copies of itself. |

Up to **20 unique agents** in the roster; the coordinator may spawn **multiple copies** of each. **One level of delegation only** — depth > 1 is ignored.

---

## Threads

The session-level event stream is the **primary thread** — it shows the coordinator's trace plus a condensed view of subagent activity (thread status transitions and cross-thread messages, not every subagent tool call). Drill into a specific subagent via the per-thread endpoints:

| Operation | HTTP | SDK (`client.beta.sessions.threads.*`) |
|---|---|---|
| List threads | `GET /v1/sessions/{sid}/threads` | `.list(session_id)` |
| Retrieve one | `GET /v1/sessions/{sid}/threads/{tid}` | `.retrieve(thread_id, session_id=...)` |
| Archive | `POST /v1/sessions/{sid}/threads/{tid}/archive` | `.archive(thread_id, session_id=...)` |
| List thread events | `GET /v1/sessions/{sid}/threads/{tid}/events` | `.events.list(thread_id, session_id=...)` |
| Stream thread events | `GET /v1/sessions/{sid}/threads/{tid}/stream` | `.events.stream(thread_id, session_id=...)` |

Each `SessionThread` carries `id`, `status` (`running` | `idle` | `rescheduling` | `terminated`), `agent` (a resolved snapshot of the agent config — `id`, `name`, `model`, `system`, `tools`, `skills`, `mcp_servers`, `version`), `parent_thread_id` (null for the primary thread, which is included in the list), `archived_at`, and optional `stats`/`usage`. **Session status aggregates thread statuses** — if any thread is `running`, `session.status` is `running`. Max **25 concurrent threads**. When draining a per-thread stream, break on `session.thread_status_idle` (and check its `stop_reason` as you would for the session-level idle).

---

## Multiagent events (on the session stream)

| Event | Payload highlights | Meaning |
|---|---|---|
| `session.thread_created` | `session_thread_id`, `agent_name` | A new thread was created. |
| `session.thread_status_running` | `session_thread_id`, `agent_name` | Thread started activity. |
| `session.thread_status_idle` | `session_thread_id`, `agent_name`, **`stop_reason`** | Thread is awaiting input. Inspect `stop_reason` (same shape as `session.status_idle.stop_reason`). |
| `session.thread_status_rescheduled` | `session_thread_id`, `agent_name` | Thread is rescheduling after a retryable error. |
| `session.thread_status_terminated` | `session_thread_id`, `agent_name` | Thread was archived or hit a terminal error. |
| `agent.thread_message_sent` | `to_session_thread_id`, `to_agent_name`, `content` | Coordinator sent a follow-up to another thread. |
| `agent.thread_message_received` | `from_session_thread_id`, `from_agent_name`, `content` | An agent delivered its result to the coordinator. |

---

## Tool permissions and custom tools from subagent threads

When a subagent needs your client (an `always_ask` confirmation, or a custom tool result), the request is **cross-posted to the primary thread** with `session_thread_id` identifying the originating thread — so you only need to watch the session stream. Reply with `user.tool_confirmation` (carrying `tool_use_id`) or `user.custom_tool_result` (carrying `custom_tool_use_id`), and **echo the `session_thread_id` from the originating event** (the SDK param type and docstring expect it). The server also routes by the tool-use ID, so the echo is belt-and-suspenders rather than load-bearing — but include it.

```python
for event_id in stop.event_ids:
    pending = events_by_id[event_id]
    confirmation = {
        "type": "user.tool_confirmation",
        "tool_use_id": event_id,
        "result": "allow",
    }
    if pending.session_thread_id is not None:
        confirmation["session_thread_id"] = pending.session_thread_id
    client.beta.sessions.events.send(session.id, events=[confirmation])
```

The same pattern applies to `user.custom_tool_result`.

---

## Pitfalls

- **Don't put the roster on `sessions.create()` or in `tools[]`.** `multiagent` is a top-level agent field; update the coordinator, then start a session that references it.
- **Don't assume shared context.** Threads share the filesystem but not conversation history or tools. If the coordinator needs a subagent to act on something, it must say so in the delegated message (or write it to disk).
- **Depth > 1 is ignored.** A subagent's own `multiagent` roster (if any) doesn't cascade — only the session's coordinator delegates.

For per-language bindings beyond Python, WebFetch `https://platform.claude.com/docs/en/managed-agents/multi-agent.md` (see `shared/live-sources.md`).

FILE:shared/managed-agents-onboarding.md
# Managed Agents — Onboarding Flow

> **Invoked via `/claude-api managed-agents-onboard`?** You're in the right place. Run the interview below — don't summarize it back to the user, ask the questions.

Use this when a user wants to set up a Managed Agent from scratch: **branch on know-vs-explore → configure the template → set up the session → pre-flight viability check → emit working code.** The pre-flight check (§3) is not optional — a setup missing a tool, credential, or data access it needs will fail mid-run, and the gap is usually visible at setup time.

> Read `shared/managed-agents-core.md` alongside this — it has full detail for each knob. This doc is the interview script, not the reference.

---

Claude Managed Agents is a hosted agent: Anthropic runs the agent loop on its orchestration layer and provisions a sandboxed container per session where the agent's tools execute (or, with a `self_hosted` environment, your own worker runs the tools — see `shared/managed-agents-self-hosted-sandboxes.md`). You supply the agent config and the environment config; the harness — event stream, sandbox orchestration, prompt caching, context compaction, and extended thinking — is handled for you.

**What you supply:**
- **An agent config** — tools, skills, model, system prompt. Reusable and versioned.
- **An environment config** — the sandbox your agent's tools execute in (`cloud`: networking, packages; or `self_hosted`: your own infra). Reusable across agents.

Each run of the agent is a **session**.

---

## 1. Know or explore?

Ask the user:

> Do you already know the agent you want to build, or would you like to explore some common patterns first?

### Explore path — show the patterns

Four shapes, same runtime code path (`sessions.create()` → `sessions.events.send()` → stream). Only the trigger and sink differ.

| Pattern | Trigger | Example |
|---|---|---|
| Event-triggered | Webhook | GitHub PR push → CMA (GitHub tool) → Slack |
| Scheduled | Cron | Daily brief: browser + GitHub + Jira → CMA → Slack |
| Fire-and-forget PR | Human | Slack slash-command → CMA (GitHub tool) → PR passing CI |
| Research + dashboard | Human | Topic → CMA (web search + `frontend-design` skill) → HTML dashboard |

Ask which shape fits, then continue with the Know path using it as the reference.

### Know path — configure template

Three rounds. Batch the questions in each round; don't ask them one at a time.

**Round A — Tools.** Start here; it's the most concrete part. Three types; ask which the user wants (any combination):

| Type | What it is | How to guide |
|---|---|---|
| **Prebuilt Claude Agent tools** (`agent_toolset_20260401`) | Ready-to-use: `bash`, `read`, `write`, `edit`, `glob`, `grep`, `web_fetch`, `web_search`. Enable all at once, or individually via `enabled: true/false`. | Recommend enabling the full toolset. List the 8 tools so the user knows what they're getting. Full detail: `shared/managed-agents-tools.md` → Agent Toolset. |
| **MCP tools** | Third-party integrations (GitHub, Linear, Asana, etc.) via `mcp_toolset`. Credentials live in a vault, not inline. | Ask which services. For each, walk through MCP server URL + vault credentials. Full detail: `shared/managed-agents-tools.md` → MCP Servers + Vaults. |
| **Custom tools** | The user's own app handles these tool calls — agent fires `agent.custom_tool_use`, the app sends a result message back. | Ask for each tool: name, description, input schema. The app code that handles the event is *their* code — don't generate it. Full detail: `shared/managed-agents-tools.md` → Custom Tools. |

**Round B — Skills, files, and repos.** What the agent has on hand when it starts.

*Skills* — two types; both work the same way — Claude auto-uses them when relevant. Max 20 per agent.
- [ ] **Pre-built Agent Skills**: `xlsx`, `docx`, `pptx`, `pdf`. Reference by name.
- [ ] **Custom Skills**: skills uploaded to the user's org via the Skills API. Reference by `skill_id` + optional `version`. If the skill doesn't exist yet, walk the user through `POST /v1/skills` + `POST /v1/skills/{id}/versions` (beta header `skills-2025-10-02`). Full detail: `shared/managed-agents-tools.md` → Skills + Skills API.

*GitHub repositories* — any repos the agent needs on-disk? For each:
- [ ] Repo URL (`https://github.com/org/repo`)
- [ ] `authorization_token` (PAT or GitHub App token scoped to the repo)
- [ ] Optional `mount_path` (defaults to `/workspace/<repo-name>`) and `checkout` (branch or SHA)

Emit as `resources: [{type: "github_repository", url, authorization_token, ...}]`. Full detail: `shared/managed-agents-environments.md` → GitHub Repositories.

> ‼️ **PR creation needs the GitHub MCP server too.** `github_repository` gives filesystem access only — to open PRs, also attach the GitHub MCP server in Round A and credential it via a vault. The workflow is: edit files in the mounted repo → push branch via `bash` → create PR via the MCP `create_pull_request` tool.

*Files* — any local files to seed the session with? For each:
- [ ] Upload via the Files API → persist `file_id`
- [ ] Choose a `mount_path` — absolute, e.g. `/workspace/data.csv` (parents auto-created; files mount read-only)

Emit as `resources: [{type: "file", file_id, mount_path}]`. Max 999 file resources. Agent working directory defaults to `/workspace`. Full detail: `shared/managed-agents-environments.md` → Files API.

**Round C — Identity, success criteria, environment:**
- [ ] Name?
- [ ] Job (one or two sentences — becomes the system prompt)?
- [ ] **What does "done" look like?** Push for concrete, checkable success criteria — not "a good report" but "a CSV with a numeric `price` column per SKU." Explicit criteria give the agent a clear target and let you verify the result; vague ones leave it guessing what "done" means. If they're gradeable, plan to wire an **Outcome** in §2 so the harness grades-and-revises against them. See `shared/managed-agents-outcomes.md`.
- [ ] Networking: unrestricted internet from the container, or lock egress to specific hosts? (If locked, MCP server domains must be in `allowed_hosts` or tools silently fail.)
- [ ] Model? (default `claude-opus-4-8`)

---

## 2. Set up the session

Per-run. Points at the agent + environment, attaches credentials, kicks off.

**Vault credentials** (if the agent declared MCP servers, or the job needs an API key for a CLI/SDK/direct API call):
- [ ] Existing vault, or create one? (`client.beta.vaults.create()` + `vaults.credentials.create()`)

Credentials are write-only. MCP credentials are matched to MCP servers by URL and auto-refreshed; `environment_variable` credentials are substituted into outbound requests at egress (the sandbox sees only a placeholder). See `shared/managed-agents-tools.md` → Vaults.

**Kickoff — pick one:**
- [ ] **Conversational:** a first `user.message` to the agent.
- [ ] **Outcome-graded** (recommended when §Round C produced checkable criteria): send a `user.define_outcome` with a rubric *instead of* a `user.message` — the harness iterates and grades against the rubric until satisfied. Don't send both. See `shared/managed-agents-outcomes.md`.

Session creation blocks until all resources mount. Open the event stream before sending the kickoff. Stream is SSE; break on `session.status_terminated`, or on `session.status_idle` with a terminal `stop_reason` — i.e. anything except `requires_action`, which fires transiently while the session waits on a tool confirmation or custom-tool result (see `shared/managed-agents-client-patterns.md` Pattern 5). Usage lands on `span.model_request_end`. Agent-written artifacts end up in `/mnt/session/outputs/` — download via `files.list({scope_id: session.id, betas: ["managed-agents-2026-04-01"]})`.

**Console escape hatch.** In the runtime block you emit, print the session's Console URL right after `sessions.create()` so the user can watch it in the UI while iterating: `print(f"Watch in Console: https://platform.claude.com/workspaces/default/sessions/{session.id}")` (swap `default` for the user's workspace slug if they named one).

---

## 3. Pre-flight viability check — reconcile the job against the resources

**Do this before emitting any code.** A common, avoidable failure is an under-resourced run: the ask is clear, but the agent is missing a tool, a credential, data access, or the context to act. The agent discovers the gap a few turns in, flails, and gives up — burning the budget to produce nothing. The gap is usually visible at setup time. Catch it here, not after the session fails.

Walk the stated job clause by clause. For each action the agent must take, confirm a resource covers it — and name the gap out loud if one doesn't:

| Gap class | Check | If missing |
|---|---|---|
| **Tool / integration** (most catchable upfront — config is statically inspectable) | Every verb in the job maps to an enabled tool or MCP server. "Triage tickets" → a ticketing MCP server; "open a PR" → GitHub MCP server (a `github_repository` mount alone can't open PRs); "search the web" → `web_search` enabled in the toolset. | Add the tool/MCP server in §Round A, or cut the ask from the job. |
| **Credential / access** | Every MCP server has a vault credential attached (§2). Every external host the job touches is reachable — networking `unrestricted`, or the host is in `allowed_hosts`. | Create/attach the vault; widen `allowed_hosts`. These don't fail until runtime — the smoke-test in §4 is how you surface them cheaply. |
| **Data** | Every file, dataset, or repo the job references is mounted as a `resource` (file, `github_repository`, or memory store). | Upload + mount it in §Round B, or tell the agent where to fetch it from. |
| **Prompt quality / criteria** | The job is specific enough to act on, and "done" is checkable (§Round C). | Tighten the job; wire an Outcome. |

State any unmet gaps to the user and resolve them before generating code. Don't emit a config you already know is under-resourced — an agent can't complete a task it lacks the tools, credentials, or data for.

---

## 4. Emit the code

Go straight from the last interview answer to the code — no preamble about the setup-vs-runtime split, no "the critical thing to internalize…", no lecture about `agents.create()` being one-time. The two-block structure below already shows that; don't narrate it. Generate **two clearly-separated blocks**:

**Block 1 — Setup (run once, store the IDs).** Prefer emitting this as **YAML files + `ant` CLI commands** — agents and environments are version-controlled definitions, and the CLI flow is what users should check into their repo and run from CI. Fall back to SDK code only if the user explicitly wants setup in-language or the `ant` CLI is unavailable.

Emit:
1. `<name>.agent.yaml` with everything from §Round A–C (flat: `name`, `model`, `system`, `tools`, `mcp_servers`, `skills`)
2. `<name>.environment.yaml` with §Round C networking
3. The apply commands:
   ```sh
   AGENT_ID=$(ant beta:agents create < <name>.agent.yaml --transform id -r)
   ENV_ID=$(ant beta:environments create < <name>.environment.yaml --transform id -r)
   # CI sync: ant beta:agents update --agent-id "$AGENT_ID" --version N < <name>.agent.yaml
   ```

See `shared/anthropic-cli.md` for the full CLI reference. If emitting SDK code instead, label it `# ONE-TIME SETUP — run once, save the IDs to config/.env` and call `environments.create()` → `agents.create()`.

**Block 2 — Runtime (run on every invocation).** This is SDK code in the detected language (Python/TS/cURL — see SKILL.md → Language Detection). The runtime path needs to react programmatically to events (tool confirmations, custom tool results, reconnect), which is SDK territory — don't emit shell loops here.
1. Load `env_id` + `agent_id` from config/env
2. `sessions.create(agent=AGENT_ID, environment_id=ENV_ID, resources=[...], vault_ids=[...])` — this blocks until resources mount, so a bad file/repo mount surfaces *here*, before any tokens are spent.
3. **Smoke-test first when the job depends on MCP servers, credentials, or reachable hosts.** Credential and MCP-connectivity failures don't surface at `sessions.create()` — only when the agent first tries to use them. Send one cheap probe turn ("Confirm you can reach <service> and list 1–2 items; don't start the task yet"), check it succeeded, *then* send the real kickoff. A few hundred tokens here beats a runaway session that flails on a missing credential and gives up. Skip for agents with no external dependencies.
4. Open stream, `events.send()` the kickoff (a `user.message`, or a `user.define_outcome` if §2 chose the outcome-graded path), loop until `session.status_terminated` or `session.status_idle && stop_reason.type !== 'requires_action'` (see `shared/managed-agents-client-patterns.md` Pattern 5 for the full gate — do not break on bare `session.status_idle`)

> ⚠️ **Never emit `agents.create()` and `sessions.create()` in the same unguarded block.** That teaches the user to create a new agent on every run — the #1 anti-pattern. If they need a single script, wrap agent creation in `if not os.getenv("AGENT_ID"):`.

Pull exact syntax from `python/managed-agents/README.md`, `typescript/managed-agents/README.md`, or `curl/managed-agents.md`. Don't invent field names.

FILE:shared/managed-agents-outcomes.md
# Managed Agents — Outcomes

An **outcome** elevates a session from *conversation* to *work*: you state what "done" looks like, and the harness runs an iterate → grade → revise loop until the artifact meets the rubric, hits `max_iterations`, or is interrupted. A separate **grader** (independent context window) scores each iteration against your rubric and feeds per-criterion gaps back to the agent.

The SDK sets the `managed-agents-2026-04-01` beta header automatically on all `client.beta.sessions.*` calls; no additional header is required for outcomes.

---

## The `user.define_outcome` event

Outcomes are not a field on `sessions.create()`. You create a normal session, then send a `user.define_outcome` event. The agent starts working on receipt — **do not also send a `user.message`** to kick it off.

```python
session = client.beta.sessions.create(
    agent=AGENT_ID,
    environment_id=ENVIRONMENT_ID,
    title="Financial analysis on Costco",
)

client.beta.sessions.events.send(
    session_id=session.id,
    events=[
        {
            "type": "user.define_outcome",
            "description": "Build a DCF model for Costco in .xlsx",
            "rubric": {"type": "text", "content": RUBRIC_MD},
            # or: "rubric": {"type": "file", "file_id": rubric.id}
            "max_iterations": 5,  # optional; default 3, max 20
        }
    ],
)
```

| Field | Type | Notes |
|---|---|---|
| `type` | `"user.define_outcome"` | |
| `description` | string | The task. This is what the agent works toward — no separate `user.message` needed. |
| `rubric` | `{type: "text", content}` \| `{type: "file", file_id}` | **Required.** Markdown with explicit, independently gradeable criteria. Upload once via `client.beta.files.upload(...)` (beta `files-api-2025-04-14`) to reuse across sessions. |
| `max_iterations` | int | Optional. Default **3**, max **20**. |

The event is echoed back on the stream with a server-assigned `outcome_id` and `processed_at`.

> **Writing rubrics.** Use explicit, gradeable criteria ("CSV has a numeric `price` column"), not vibes ("data looks good") — the grader scores each criterion independently, so vague criteria produce noisy loops. If you don't have a rubric, have Claude analyze a known-good artifact and turn that analysis into one.

---

## Outcome-specific events

These appear on the standard event stream (`sessions.events.stream` / `.list`) alongside the usual `agent.*` / `session.*` events.

| Event | Payload highlights | Meaning |
|---|---|---|
| `span.outcome_evaluation_start` | `outcome_id`, `iteration` (0-indexed) | Grader began scoring iteration *N*. |
| `span.outcome_evaluation_ongoing` | `outcome_id` | Heartbeat while the grader runs. Grader reasoning is opaque — you see *that* it's working, not *what* it's thinking. |
| `span.outcome_evaluation_end` | `outcome_evaluation_start_id`, `outcome_id`, `iteration`, `result`, `explanation`, `usage` | Grader finished one iteration. `result` drives what happens next (table below). |

### `span.outcome_evaluation_end.result`

| `result` | Next |
|---|---|
| `satisfied` | Session → `idle`. Terminal for this outcome. |
| `needs_revision` | Agent starts another iteration. |
| `max_iterations_reached` | No further grader cycles. Agent may run one final revision, then session → `idle`. |
| `failed` | Session → `idle`. Rubric fundamentally doesn't match the task (e.g. description and rubric contradict). |
| `interrupted` | Only emitted if `_start` had already fired before a `user.interrupt` arrived. |

```json
{
  "type": "span.outcome_evaluation_end",
  "id": "sevt_01jkl...",
  "outcome_evaluation_start_id": "sevt_01def...",
  "outcome_id": "outc_01a...",
  "result": "satisfied",
  "explanation": "All 12 criteria met: revenue projections use 5 years of historical data, ...",
  "iteration": 0,
  "usage": { "input_tokens": 2400, "output_tokens": 350, "cache_creation_input_tokens": 0, "cache_read_input_tokens": 1800 },
  "processed_at": "2026-03-25T14:03:00Z"
}
```

---

## Checking status & retrieving deliverables

**Status** — either watch the stream for `span.outcome_evaluation_end`, or poll the session and read `outcome_evaluations`:

```python
session = client.beta.sessions.retrieve(session.id)
for ev in session.outcome_evaluations:
    print(f"{ev.outcome_id}: {ev.result}")  # outc_01a...: satisfied
```

**Deliverables** — the agent writes to `/mnt/session/outputs/`. Once idle, fetch via the Files API with `scope_id=session.id`. This is the same session-outputs mechanism documented in `shared/managed-agents-environments.md` → Session outputs (including the dual-beta-header requirement on `files.list`).

---

## Interaction rules & pitfalls

- **One outcome at a time.** Chain by sending the next `user.define_outcome` only after the previous one's terminal `span.outcome_evaluation_end` (`satisfied` / `max_iterations_reached` / `failed` / `interrupted`). The session retains history across chained outcomes.
- **Steering is allowed but optional.** You *may* send `user.message` events mid-outcome to nudge direction, but the agent already knows to keep working until terminal — don't send "keep going" prompts.
- **`user.interrupt` pauses the current outcome** — it marks `result: "interrupted"` and leaves the session `idle`, ready for a new outcome or conversational turn.
- **After terminal, the session is reusable** — continue conversationally or define a new outcome.
- **Outcome ≠ session-create field.** Don't put `outcome`, `rubric`, or `description` on `sessions.create()` — outcomes are always sent as a `user.define_outcome` event.
- **Idle-break gate is unchanged.** In your drain loop, keep using `event.type === 'session.status_idle' && event.stop_reason?.type !== 'requires_action'` — do **not** gate on `span.outcome_evaluation_end` alone (on `needs_revision` the session keeps running). See `shared/managed-agents-client-patterns.md` Pattern 5.

For the raw HTTP shapes and per-language SDK bindings beyond Python, WebFetch `https://platform.claude.com/docs/en/managed-agents/define-outcomes.md` (see `shared/live-sources.md`).

FILE:shared/managed-agents-overview.md
# Managed Agents — Overview

Managed Agents provisions a container per session as the agent's workspace. The agent loop runs on Anthropic's orchestration layer; the container is where the agent's *tools* execute — bash commands, file operations, code. You create a persisted **Agent** config (model, system prompt, tools, MCP servers, skills), then start **Sessions** that reference it. The session streams events back to you; you send user messages and tool results in.

## ⚠️ THE MANDATORY FLOW: Agent (once) → Session (every run)

**Why agents are separate objects: versioning.** An agent is a persisted, versioned config — every update creates a new immutable version, and sessions pin to a version at creation time. This lets you iterate on the agent (tweak the prompt, add a tool) without breaking sessions already running, roll back if a change regresses, and A/B test versions side-by-side. None of that works if you `agents.create()` fresh on every run.

Every session references a pre-created `/v1/agents` object. Create the agent once, store the ID, and reuse it across runs.

| Step | Call | Frequency |
|---|---|---|
| 1 | `POST /v1/agents` — `model`, `system`, `tools`, `mcp_servers`, `skills` live here | **ONCE.** Store `agent.id` **and** `agent.version`. |
| 2 | `POST /v1/sessions` — `agent: "agent_abc123"` or `{type: "agent", id, version}` | **Every run.** String shorthand uses latest version. |

If you're about to write `sessions.create()` with `model`, `system`, or `tools` on the session body — **stop**. Those fields live on `agents.create()`. The session takes a *pointer* only.

**When generating code, separate setup from runtime.** `agents.create()` belongs in a setup script (or a guarded `if agent_id is None:` block), not at the top of the hot path. If the user's code calls `agents.create()` on every invocation, they're accumulating orphaned agents and paying the create latency for nothing. The correct shape is: create once → persist the ID (config file, env var, secrets manager) → every run loads the ID and calls `sessions.create()`.

**To change the agent's behavior, use `POST /v1/agents/{id}` — don't create a new one.** Each update bumps the version; running sessions keep their pinned version, new sessions get the latest (or pin explicitly via `{type: "agent", id, version}`). See `shared/managed-agents-core.md` → Agents → Versioning. To change `tools`/`mcp_servers`/`vault_ids` on **one running session** without touching the agent object, use `sessions.update()` — see `shared/managed-agents-core.md` → Updating the agent configuration mid-session.

## Beta Headers

Managed Agents is in beta. The SDK sets required beta headers automatically:

| Beta Header                    | What it enables                                      |
| ------------------------------ | ---------------------------------------------------- |
| `managed-agents-2026-04-01`    | Agents, Environments, Sessions, Events, Session Resources, Session Threads, Outcomes, Multiagent, Vaults, Credentials, Memory Stores, Deployments |
| `skills-2025-10-02`            | Skills API (for managing custom skill definitions)   |
| `files-api-2025-04-14`         | Files API for file uploads                           |

**Which beta header goes where:** The SDK sets `managed-agents-2026-04-01` automatically on `client.beta.{agents,environments,sessions,vaults,memory_stores,deployments,deployment_runs}.*` calls, and `files-api-2025-04-14` / `skills-2025-10-02` automatically on `client.beta.files.*` / `client.beta.skills.*` calls. You do NOT need to add the Skills or Files beta header when calling Managed Agents endpoints. **Exception — session-scoped file listing:** `client.beta.files.list({scope_id: session.id})` is a Files endpoint that takes a Managed Agents parameter, so it needs **both** headers. Pass `betas: ["managed-agents-2026-04-01"]` explicitly on that call (the SDK adds the Files header; you add the Managed Agents one). See `shared/managed-agents-environments.md` → Session outputs.


## Reading Guide

| User wants to...                       | Read these files                                        |
| -------------------------------------- | ------------------------------------------------------- |
| **Get started from scratch / "help me set up an agent"** | `shared/managed-agents-onboarding.md` — guided interview (WHERE→WHO→WHAT→WATCH), then emit code |
| Understand how the API works           | `shared/managed-agents-core.md`                         |
| See the full endpoint reference        | `shared/managed-agents-api-reference.md`                |
| **Create an agent** (required first step) | `shared/managed-agents-core.md` (Agents section) + language file |
| Update/version an agent                | `shared/managed-agents-core.md` (Agents → Versioning) — update, don't re-create |
| Create a session                       | `shared/managed-agents-core.md` + `{lang}/managed-agents/README.md` |
| Configure tools and permissions        | `shared/managed-agents-tools.md`                        |
| Set up MCP servers                     | `shared/managed-agents-tools.md` (MCP Servers section)  |
| Stream events / handle tool_use        | `shared/managed-agents-events.md` + language file       |
| Get notified of session state changes via webhook (no polling) | `shared/managed-agents-webhooks.md` — Console-registered endpoint, HMAC verify, thin payload + fetch |
| Define an outcome / rubric-graded iterate loop | `shared/managed-agents-outcomes.md` — `user.define_outcome` event, grader, `span.outcome_evaluation_*` events |
| Coordinate multiple agents / subagents / threads | `shared/managed-agents-multiagent.md` — `multiagent: {type: "coordinator", agents: [...]}` on the agent, session threads, cross-posted tool confirmations |
| Set up environments                    | `shared/managed-agents-environments.md` + language file |
| Run tool execution in your own infra / VPC (self-hosted sandbox) | `shared/managed-agents-self-hosted-sandboxes.md` — `config:{type:"self_hosted"}`, `ANTHROPIC_ENVIRONMENT_KEY`, `EnvironmentWorker.run()` / `ant beta:worker poll` |
| Upload files / attach repos            | `shared/managed-agents-environments.md` (Resources)     |
| Give agents persistent memory across sessions | `shared/managed-agents-memory.md` — memory stores, `memory_store` session resource, preconditions, versions/redact |
| Define agents/environments as version-controlled YAML; drive the API from the shell | `shared/anthropic-cli.md` — `ant beta:agents create < agent.yaml`, `--transform`, `@file` inlining |
| Store credentials (MCP auth, API keys for CLIs/SDKs) | `shared/managed-agents-tools.md` (Vaults section) — `mcp_oauth` / `static_bearer` / `environment_variable` |
| Call a non-MCP API / CLI that needs a secret | `shared/managed-agents-tools.md` (Vaults section) — `environment_variable` credential, substituted at egress. If that doesn't fit (e.g. self-hosted sandboxes), `shared/managed-agents-client-patterns.md` Pattern 9 keeps the secret host-side via a custom tool |
| Run an agent on a recurring cron schedule | `shared/managed-agents-scheduled-deployments.md` — deployments, deployment runs, pause/auto-pause |

## Common Pitfalls

- **Agent FIRST, then session — NO EXCEPTIONS** — the session's `agent` field accepts **only** a string ID or `{type: "agent", id, version}`. `model`, `system`, `tools`, `mcp_servers`, `skills` are **top-level fields on `POST /v1/agents`**, never on `sessions.create()`. If the user hasn't created an agent, that is step zero of every example.
- **Agent ONCE, not every run** — `agents.create()` is a setup step. Store the returned `agent_id` and reuse it; don't call `agents.create()` at the top of your hot path. If the agent's config needs to change, `POST /v1/agents/{id}` — each update creates a new version, and sessions can pin to a specific version for reproducibility.
- **MCP auth goes through vaults** — the agent's `mcp_servers` array declares `{type, name, url}` only (no auth). Credentials live in vaults (`client.beta.vaults.credentials.create`) and attach to sessions via `vault_ids`. Anthropic auto-refreshes OAuth tokens using the stored refresh token. Vaults also hold `environment_variable` credentials for non-MCP services (CLIs, SDKs, direct API calls) — substituted at egress, never visible in the sandbox.
- **Reconcile resources before the first run** — a session with a clear ask but a missing tool, credential, data mount, or context will discover the gap mid-run, then flail and give up. Before creating the session, check that every action in the task maps to a configured tool/MCP server, every MCP server has a vault credential, and every referenced file/host is mounted/reachable. When helping a user set one up, run the reconciliation in `shared/managed-agents-onboarding.md` → §3 Pre-flight viability check.
- **Stream to get events** — `GET /v1/sessions/{id}/events/stream` is the primary way to receive agent output in real-time.
- **SSE stream has no replay — reconnect with consolidation** — if the stream drops while a `agent.tool_use`, `agent.mcp_tool_use`, or `agent.custom_tool_use` is pending resolution (`user.tool_confirmation` for the first two, `user.custom_tool_result` for the last one), the session deadlocks (client disconnects → session idles → reconnect happens → no client resolution happens). On every (re)connect: open stream with `GET /v1/sessions/{id}/events/stream` , fetch `GET /v1/sessions/{id}/events`, dedupe by event ID, then proceed. See `shared/managed-agents-events.md` → Reconnecting after a dropped stream.
- **Don't trust HTTP-library timeouts as wall-clock caps** — `requests` `timeout=(c, r)` and `httpx.Timeout(n)` are *per-chunk* read timeouts; they reset every byte, so a trickling connection can block indefinitely. For a hard deadline on raw-HTTP polling, track `time.monotonic()` at the loop level and bail explicitly. Prefer the SDK's `sessions.events.stream()` / `session.events.list()` over hand-rolled HTTP. See `shared/managed-agents-events.md` → Receiving Events.
- **Messages queue** — you can send events while the session is `running` or `idle`; they're processed in order. No need to wait for a response before sending the next message.
- **Environment `config.type` is `"cloud"` or `"self_hosted"`** — `cloud` runs the container on Anthropic's infrastructure; `self_hosted` moves tool execution to your own (see `shared/managed-agents-self-hosted-sandboxes.md`).
- **Archive is permanent on every resource** — archiving an agent, environment, session, vault, credential, or memory store makes it read-only with no unarchive. For agents, environments, and memory stores specifically, archived resources cannot be referenced by new sessions (existing sessions continue). Do not call `.archive()` on a production agent, environment, or memory store as cleanup — **always confirm with the user before archiving**.

FILE:shared/managed-agents-scheduled-deployments.md
# Managed Agents — Scheduled Deployments

A **scheduled deployment** runs an agent on a recurring cron schedule — each firing creates a session autonomously. Use it for predictable-cadence work: nightly triage, weekly compliance scans, hourly monitors.

Requires the `managed-agents-2026-04-01` beta header (the SDK sets it automatically for `client.beta.deployments.*` / `client.beta.deployment_runs.*` calls).

## Create a deployment

A deployment bundles everything a session needs (agent, environment, optional files / GitHub / memory stores / vaults) plus a `schedule` and the `initial_events` that kick off each run:

- `agent` and `environment_id` are required — same shapes as `sessions.create` (see `shared/managed-agents-core.md`).
- `initial_events` must contain the starting `user.message`.
- `schedule` takes a cron `expression` and an IANA `timezone`. Minute-level granularity is the maximum.

```bash
curl -fsSL https://api.anthropic.com/v1/deployments \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: managed-agents-2026-04-01" \
  -H "content-type: application/json" \
  -d @- <<EOF
{
  "name": "Weekly compliance scan",
  "agent": "$AGENT_ID",
  "environment_id": "$ENVIRONMENT_ID",
  "initial_events": [
    {"type": "user.message", "content": [{"type": "text", "text": "Run the weekly compliance scan."}]}
  ],
  "schedule": {
    "type": "cron",
    "expression": "0 20 * * 5",
    "timezone": "America/New_York"
  }
}
EOF
```

```python
deployment = client.beta.deployments.create(
    name="Weekly compliance scan",
    agent=agent.id,
    environment_id=environment.id,
    initial_events=[
        {
            "type": "user.message",
            "content": [{"type": "text", "text": "Run the weekly compliance scan."}],
        },
    ],
    schedule={
        "type": "cron",
        "expression": "0 20 * * 5",
        "timezone": "America/New_York",
    },
)
```

The response is a deployment object (`depl_` ID prefix). Check `schedule.upcoming_runs_at` — the next fire times — to confirm the schedule parses the way you intended:

```json
{
  "id": "depl_01xyz",
  "status": "active",
  "paused_reason": null,
  "schedule": {
    "type": "cron",
    "expression": "0 20 * * 5",
    "timezone": "America/New_York",
    "last_run_at": null,
    "upcoming_runs_at": ["2026-05-09T00:00:00Z", "2026-05-16T00:00:00Z", "2026-05-23T00:00:00Z"]
  }
}
```

Deployments may apply up to **10 seconds of jitter** to distribute load. Maximum **1000 scheduled deployments per organization** (contact Anthropic support for more).

### Cron and timezone semantics

- **Expression:** standard POSIX cron (`minute hour day-of-month month day-of-week`).
- **Timezone:** IANA identifier (e.g. `"America/Los_Angeles"`).
- **DST:** literal wall-clock matching — `"0 20 * * *"` in `America/New_York` fires at 8:00 PM local regardless of EST/EDT.

> ⚠️ **DST edge:** wall-clock times that don't exist on a spring-forward day (e.g. 2AM) are **skipped**; times that occur twice on a fall-back day **fire twice**. Schedule outside the 1–3AM local window, or use UTC, when missed or duplicate executions are unacceptable.

## Deployment runs

Every trigger attempt — successful or not — writes a **deployment run** record (`drun_` prefix), so you can audit failures independent of the session lifecycle. A successful run carries the created `session_id`; follow that session via the event stream (`shared/managed-agents-events.md`) or webhooks (`shared/managed-agents-webhooks.md`) as usual. A failed run carries an `error` whose `type` explains why session creation was rejected.

```python
# All runs for a deployment
for run in client.beta.deployment_runs.list(deployment_id=deployment.id):
    print(run.created_at, run.session_id or run.error.type)

# Failures only
for run in client.beta.deployment_runs.list(deployment_id=deployment.id, has_error=True):
    print(run.created_at, run.error.type, run.error.message)
```

```typescript
for await (const run of client.beta.deploymentRuns.list({
  deployment_id: deployment.id,
  has_error: true,
})) {
  console.log(run.created_at, run.error?.type, run.error?.message);
}
```

Raw HTTP: `GET /v1/deployment_runs?deployment_id=...&has_error=true`.

A failed run looks like:

```json
{
  "type": "deployment_run",
  "id": "drun_01abc124",
  "deployment_id": "depl_01xyz",
  "trigger_context": { "type": "schedule", "scheduled_at": "2026-05-09T00:00:00Z" },
  "session_id": null,
  "error": { "type": "environment_archived", "message": "environment `env_01abc` is archived" },
  "agent": { "type": "agent", "id": "agent_01ghi789", "version": 3 },
  "created_at": "2026-05-09T00:00:01Z"
}
```

Error types include `environment_archived`, `agent_archived`, `vault_not_found`, `session_rate_limited`, and `service_unavailable`.

## Lifecycle: pause / unpause / archive

| Operation | SDK | Effect |
|---|---|---|
| Pause | `client.beta.deployments.pause(id)` | Suppresses scheduled triggers go-forward. Sessions already running continue. **Manual runs are still permitted while paused.** Sets `paused_reason: {"type": "manual"}`. |
| Unpause | `client.beta.deployments.unpause(id)` | Resumes from the next scheduled occurrence. **Missed triggers are not backfilled.** Clears `paused_reason`. |
| Archive | `client.beta.deployments.archive(id)` | **Terminal** — the schedule stops and the deployment can no longer be modified. Use pause for anything reversible. |

Raw HTTP: `POST /v1/deployments/{deployment_id}/pause` (likewise `/unpause`, `/archive`).

### Failure behavior

- **Rate-limited:** recorded immediately as a `session_rate_limited` run, **no retry** — the schedule simply tries again at the next occurrence. (Rate limits on API calls *inside* a session are handled by the session itself.)
- **Other failed runs** (e.g. `environment_archived`, `vault_not_found`, `service_unavailable`): the run records the `error.type` — monitor runs and fix the referenced resource, or pause the deployment.
- **Agent archived or deleted:** the deployment is automatically **archived** (terminal) and no further sessions are created.

## Manual runs

`POST /v1/deployments/{deployment_id}/run` (SDK: `client.beta.deployments.run(id)`) creates a session immediately and writes a run with `trigger_context.type: "manual"`. Use it to **test a deployment before committing to the schedule** — and remember it works even while the deployment is paused.

FILE:shared/managed-agents-self-hosted-sandboxes.md
# Managed Agents — Self-Hosted Sandboxes

With `config.type: "self_hosted"`, the **agent loop stays on Anthropic's orchestration layer** but **tool execution moves to infrastructure you control** — bash, file ops, and code run inside your container, so filesystem contents and network egress never leave your environment. Contrast with `config.type: "cloud"`, where Anthropic runs the container. Connectivity is **outbound-only**: your worker long-polls Anthropic's work queue; Anthropic never dials into your network.

## Flow

```
1. Create environment:      config: {type: "self_hosted"}        → env_...
2. Generate environment key (Console, on the environment page)   → sk-ant-oat01-...  as ANTHROPIC_ENVIRONMENT_KEY
3. Run a worker:            EnvironmentWorker.run()  or  ant beta:worker poll
4. Sessions reference       environment_id=env_... exactly as for cloud
```

## Create the environment

```python
client = anthropic.Anthropic()

environment = client.beta.environments.create(
    name="self-hosted", config={"type": "self_hosted"}
)
```

`{"type": "self_hosted"}` is the entire config — there are no pool, capacity, or networking sub-fields; you control those on your side.

## Run a worker — SDK (primary path)

`EnvironmentWorker` wraps the poll → dispatch → tool-execute loop. `.run()` is the always-on loop; `.run_one()` / `.runOne()` handles one work item (for webhook-driven wake).

**Python — always-on:**

```python
import asyncio
import os
from anthropic import AsyncAnthropic
from anthropic.lib.environments import EnvironmentWorker


async def main() -> None:
    environment_key = os.environ["ANTHROPIC_ENVIRONMENT_KEY"]
    environment_id = os.environ["ANTHROPIC_ENVIRONMENT_ID"]
    async with AsyncAnthropic(auth_token=environment_key) as client:
        await EnvironmentWorker(
            client,
            environment_id=environment_id,
            environment_key=environment_key,
            workdir="/workspace",
        ).run()


asyncio.run(main())
```

**TypeScript — always-on:**

```typescript
import Anthropic from "@anthropic-ai/sdk";
import { EnvironmentWorker } from "@anthropic-ai/sdk/helpers/beta/environments";

const environmentKey = process.env.ANTHROPIC_ENVIRONMENT_KEY!;
const environmentId = process.env.ANTHROPIC_ENVIRONMENT_ID!;
const client = new Anthropic({ authToken: environmentKey });
const ctrl = new AbortController();
process.once("SIGTERM", () => ctrl.abort());

await new EnvironmentWorker({
  client,
  environmentId,
  environmentKey,
  workdir: "/workspace",
  signal: ctrl.signal
}).run();
```

**Customizing tools.** `EnvironmentWorker` runs the built-in toolset by default. To add or replace tools, use `AgentToolContext(workdir=, client=, session_id=)` with `beta_agent_toolset(env)` / `betaAgentToolset(env)` and pass the resulting tools to the lower-level `tool_runner()`. Skills attached to the agent are downloaded into `{workdir}/skills/<name>/` before tool calls begin (`AgentToolContext` handles this when given `client` and `session_id`). Downloaded skill files are marked executable automatically by the CLI and SDK; if you implement skills download yourself, you set permissions.

> **Runtime deps:** the SDK helpers require `/bin/bash` at that exact path. The TypeScript SDK additionally requires `unzip`, `tar`, and Node.js 22+. These are resolved at fixed paths and do **not** respect `PATH` overrides.

## Run a worker — `ant` CLI (fixed tools)

The `ant` CLI ships a worker with the fixed built-in toolset (`bash`, `read`, `write`, `edit`, `glob`, `grep`). Install per `shared/anthropic-cli.md`, then:

```sh
export ANTHROPIC_ENVIRONMENT_KEY=sk-ant-oat01-...
ant beta:worker poll --environment-id env_... --workdir /workspace
```

- `--workdir` is the directory tools operate in (default `.`); tool calls are sandboxed to it.
- `--environment-key` overrides the env var.
- `--on-work <script>` runs your script per work item (e.g. to spin a fresh container per session — see Container orchestration below).
- `--unrestricted-paths`, `--max-idle` (default `60s`), `--log-format` — see `ant beta:worker poll --help`.
- Flags fall back to env vars (`ANTHROPIC_ENVIRONMENT_ID`, `ANTHROPIC_ENVIRONMENT_KEY`).
- Exits cleanly on SIGTERM/SIGINT after draining in-flight work.
- **Fixed toolset** — for custom tools, use the SDK worker above.

Inside an `--on-work` container, run `ant beta:worker run --workdir <dir>` as the entrypoint.

## Webhook-driven wake (instead of always-on)

Register a webhook for `session.status_run_started` (see `shared/managed-agents-webhooks.md`), verify the delivery, then drain one work item with `.run_one()`:

```python
import os
import anthropic
from anthropic.lib.environments import EnvironmentWorker

environment_key = os.environ["ANTHROPIC_ENVIRONMENT_KEY"]
environment_id = os.environ["ANTHROPIC_ENVIRONMENT_ID"]
client = anthropic.AsyncAnthropic(
    auth_token=environment_key,
)  # reads ANTHROPIC_WEBHOOK_SIGNING_KEY from env for webhooks.unwrap()


async def handle(raw: bytes, headers: dict[str, str]) -> dict:
    event = client.beta.webhooks.unwrap(raw.decode(), headers=headers)
    if event.data.type != "session.status_run_started":
        return {"status": "ignored"}
    await EnvironmentWorker(
        client,
        environment_id=environment_id,
        environment_key=environment_key,
        workdir="/workspace",
    ).run_one()
    return {"status": "ok"}
```

TypeScript: same shape with `client.beta.webhooks.unwrap(body, {headers})` and `new EnvironmentWorker({...}).runOne()`.

## Container orchestration (mid-level)

`EnvironmentWorker.run()` polls and executes tools in the same process. To run each session in its **own** container, use the mid-level poller in a thin orchestrator — Python `client.beta.environments.work.poller(environment_id=, environment_key=, drain=, block_ms=, reclaim_older_than_ms=, auto_stop=)`; TypeScript `new WorkPoller({client, environmentId, environmentKey, autoStop})` from `@anthropic-ai/sdk/helpers/beta/environments` — and, for each yielded `work` item, start a fresh container with these env vars injected, whose entrypoint runs `ant beta:worker run` or an `EnvironmentWorker(...).run_one()`. `block_ms` is 1–999 (or `None` for non-blocking); `reclaim_older_than_ms` re-claims items leased to a dead worker; `drain` stops once the queue is empty; `auto_stop` posts a stop signal after the iterator exits (set `False` when the launched container owns the stop call). **Go's poller has no `auto_stop` opt-out** — it calls `work.Stop` when the handler returns, so block in the handler until the session completes rather than detaching.

| Env var | Value |
|---|---|
| `ANTHROPIC_SESSION_ID` | `work.data.id` |
| `ANTHROPIC_WORK_ID` | `work.id` |
| `ANTHROPIC_ENVIRONMENT_ID` | `work.environment_id` |
| `ANTHROPIC_ENVIRONMENT_KEY` | pass through |
| `ANTHROPIC_BASE_URL` | pass through |

Skip items where `work.data.type != "session"`.

## Monitoring & control

These are **control-plane** calls — authenticate with `x-api-key` (not the environment key); `managed-agents-2026-04-01` beta header. **Call them from outside the worker host** — setting `ANTHROPIC_API_KEY` on the worker host exposes an organization-scoped credential to agent tool calls.

| SDK (`client.beta.environments.work.*`) | REST | CLI | Returns |
|---|---|---|---|
| `stats(environment_id)` | `GET /v1/environments/{id}/work/stats` | `ant beta:environments:work stats` | `{type:"work_queue_stats", depth, pending, oldest_queued_at, workers_polling}` |
| `stop(work_id, environment_id=)` | `POST /v1/environments/{id}/work/{work_id}/stop` | `ant beta:environments:work stop` | `work.state` |

## What changes vs `cloud`

| Concern | `cloud` | `self_hosted` |
|---|---|---|
| Container lifecycle, hardening, networking | Anthropic | **You** — run non-root, read-only rootfs, drop caps; egress is whatever your VPC/firewall allows |
| `file` / `github_repository` resource mounting | Anthropic mounts into the container | **You** — pass pointers via `sessions.create(metadata={...})` and have your orchestrator fetch/clone before dispatch |
| `memory_store` resources | Supported | **Not yet supported** |
| Vault `environment_variable` credentials | Supported (substituted at Anthropic-managed egress) | **Not yet supported** — egress is yours, so there's nowhere to substitute the secret. Use MCP credentials or a host-side custom tool (`shared/managed-agents-client-patterns.md` Pattern 9) |
| Built-in tools | Via `agent_toolset_20260401` | Supplied by your worker (`EnvironmentWorker` default / `beta_agent_toolset(env)` / `ant` CLI fixed set) |
| Skills download | Automatic | `EnvironmentWorker` / `AgentToolContext` fetch into `{workdir}/skills/` (needs `client` + `session_id`) |
| Claude Platform on AWS | Supported | **Not available** |
| SDK worker helpers | All SDKs | **Python, TypeScript, Go only** (`EnvironmentWorker` / poller not in Java, Ruby, PHP, or C#) — use one of those three or the `ant` CLI |

## Credentials

| Credential | Format | Scope |
|---|---|---|
| `ANTHROPIC_ENVIRONMENT_KEY` | `sk-ant-oat01-...` | One environment's work queue. Generate in Console ("Generate environment key"). Pass as `auth_token=` / `authToken` on the client **and** as `environment_key=` / `environmentKey` on `EnvironmentWorker`. Store in a secrets manager; rotate on exposure. |
| `ANTHROPIC_WEBHOOK_SIGNING_KEY` | `whsec_...` | Webhook signature verification (if using webhook-driven wake). The SDK reads this env var automatically for `client.beta.webhooks.unwrap()`. |

## Security — what you own

Container hardening; egress restriction (there is no default); `ANTHROPIC_ENVIRONMENT_KEY` custody and rotation; one workspace + environment per trust boundary when running untrusted code; least-privilege for the tool process; log retention and redaction. **Anthropic cannot**: fast-revoke a leaked environment key, verify your image or supply chain, sandbox tool execution inside your container, or enforce retention after tool output reaches your infrastructure. See the Self-Hosted Sandboxes Security page in `shared/live-sources.md` for the full checklist.

FILE:shared/managed-agents-tools.md
# Managed Agents — Tools & Skills

## Tools

### Server tools vs client tools

| Type | Who runs it | How it works |
|---|---|---|
| **Prebuilt Claude Agent tools** (`agent_toolset_20260401`) | Anthropic, on the session's container (for `cloud` envs; for `self_hosted`, **your** worker supplies and runs them — see `shared/managed-agents-self-hosted-sandboxes.md`) | File ops, bash, web search, etc. Enable all at once or configure individually with `enabled: true/false`. |
| **MCP tools** (`mcp_toolset`) | Anthropic's orchestration layer | Capabilities exposed by connected MCP servers. Grant access per-server via the toolset. |
| **Custom tools** | **You** — your application handles the call and returns results | Agent emits a `agent.custom_tool_use` event, session goes `idle`, you send back a `user.custom_tool_result` event. |

**Recommendation:** Enable all prebuilt tools via `agent_toolset_20260401`, then disable individually as needed.

**Versioning:** The toolset is a versioned, static resource. When underlying tools change, a new toolset version is created (hence `_20260401`) so you always know exactly what you're getting.

### Agent Toolset

The `agent_toolset_20260401` provides these built-in tools:

| Tool                   | Description                              |
| ---------------------- | ---------------------------------------- |
| `bash` | Execute bash commands in a shell session |
| `read` | Read a file from the local filesystem, including text, images, PDFs, and Jupyter notebooks |
| `write` | Write a file to the local filesystem |
| `edit` | Perform string replacement in a file |
| `glob` | Fast file pattern matching using glob patterns |
| `grep` | Text search using regex patterns |
| `web_fetch` | Fetch content from a URL |
| `web_search` | Search the web for information |

Enable the full toolset:

```json
{
  "tools": [
    { "type": "agent_toolset_20260401" }
  ]
}
```

### Per-Tool Configuration

Override defaults for individual tools. This example enables everything except bash:

```json
{
  "tools": [
    {
      "type": "agent_toolset_20260401",
      "default_config": { "enabled": true },
      "configs": [
        { "name": "bash", "enabled": false }
      ]
    }
  ]
}
```

| Field | Required | Description |
|---|---|---|
| `type` | ✅ | `"agent_toolset_20260401"` |
| `default_config` | ❌ | Applied to all tools. `{ "enabled": bool, "permission_policy": {...} }` |
| `configs` | ❌ | Per-tool overrides: `[{ "name": "...", "enabled": bool, "permission_policy": {...} }]` |

### Permission Policies

Control when server-executed tools (agent toolset + MCP) run automatically vs wait for approval. Does not apply to custom tools.

| Policy | Behavior |
|---|---|
| `always_allow` | Tool executes automatically (default) |
| `always_ask` | Session emits `session.status_idle` and pauses until you send a `tool_confirmation` event |

```json
{
  "type": "agent_toolset_20260401",
  "default_config": {
    "enabled": true,
    "permission_policy": { "type": "always_allow" }
  },
  "configs": [
    { "name": "bash", "permission_policy": { "type": "always_ask" } }
  ]
}
```

**Responding to `always_ask`:** Send a `user.tool_confirmation` event with `tool_use_id` from the triggering `agent_tool_use`/`mcp_tool_use` event:

```json
{ "type": "tool_confirmation", "tool_use_id": "sevt_abc123", "result": "allow" }
{ "type": "tool_confirmation", "tool_use_id": "sevt_def456", "result": "deny", "message": "Read .env.example instead" }
```

The optional `message` on a deny is delivered to the agent so it can adjust its approach.

To enable only specific tools, flip the default off and opt-in per tool:

```json
{
  "tools": [
    {
      "type": "agent_toolset_20260401",
      "default_config": { "enabled": false },
      "configs": [
        { "name": "bash", "enabled": true },
        { "name": "read", "enabled": true }
      ]
    }
  ]
}
```

### Custom Tools (Client-Side)

Custom tools are executed by **your application**, not Anthropic. The flow:

1. Agent decides to use the tool → session emits a `agent.custom_tool_use` event with inputs
2. Session goes `idle` waiting for you
3. Your application executes the tool
4. You send back a `user.custom_tool_result` event with the output
5. Session resumes `running`

No permission policy needed — you're the one executing.

```json
{
  "tools": [
    {
      "type": "custom",
      "name": "get_weather",
      "description": "Fetch current weather for a city.",
      "input_schema": {
        "type": "object",
        "properties": {
          "city": { "type": "string", "description": "City name" }
        },
        "required": ["city"]
      }
    }
  ]
}
```

### MCP Servers

MCP (Model Context Protocol) servers expose standardized third-party capabilities (e.g. Asana, GitHub, Linear). **Configuration is split across agent and vault:**

1. **Agent creation** declares which servers to connect to (`type`, `name`, `url` — no auth). The agent's `mcp_servers` array has no auth field.
2. **Vault** stores the OAuth credentials. Attach via `vault_ids` on session create.

This keeps secrets out of reusable agent definitions. Each vault credential is tied to one MCP server URL; Anthropic matches credentials to servers by URL.

**Agent side — declare servers (no auth):**

| Field | Required | Description |
|---|---|---|
| `type` | ✅ | `"url"` |
| `name` | ✅ | Unique name — referenced by `mcp_toolset.mcp_server_name` |
| `url` | ✅ | The MCP server's endpoint URL (Streamable HTTP transport) |

```json
{
  "mcp_servers": [
    { "type": "url", "name": "linear", "url": "https://mcp.linear.app/mcp" }
  ],
  "tools": [
    { "type": "mcp_toolset", "mcp_server_name": "linear" }
  ]
}
```

**Session side — attach vault:**

```json
{
  "agent": "agent_abc123",
  "environment_id": "env_abc123",
  "vault_ids": ["vlt_abc123"]
}
```

> 💡 **Per-tool enablement (empirical):** `mcp_toolset` has been observed accepting `default_config: {enabled: false}` + `configs: [{name, enabled: true}]` for an allowlist pattern. The API ref shows only the minimal `{type, mcp_server_name}` form.

> 💡 **Changing tools/MCP servers on a running session:** `sessions.update()` can replace `agent.tools`, `agent.mcp_servers`, and `vault_ids` while the session is `idle` — a session-local override that doesn't touch the agent object. See `shared/managed-agents-core.md` → Updating the agent configuration mid-session.

**Large MCP tool outputs.** If an MCP tool returns more than **100K tokens**, the output is automatically offloaded to a file in the sandbox — the agent receives a truncated preview plus the file path and can `read` the full content. No configuration required.

**Invalid vault credentials don't block session creation.** If a vault credential is invalid for a declared MCP server, the session still creates successfully; a `session.error` event describes the MCP auth failure, and auth retries on the next `session.status_idle` → `session.status_running` transition.

> ⚠️ **MCP auth tokens ≠ REST API tokens.** Hosted MCP servers (`mcp.notion.com`, `mcp.linear.app`, etc.) typically require **OAuth bearer tokens**, not the service's native API keys. A Notion `ntn_` integration token authenticates against Notion's REST API but will **not** work as a vault credential for the Notion MCP server. These are different auth systems.

### Vaults — the credential store

**Vaults** store credentials that Anthropic manages on your behalf. Two credential categories:

- **MCP credentials** (`mcp_oauth`, `static_bearer`) — keyed by `mcp_server_url`. When the agent connects to a server at that URL, the token is injected automatically. `mcp_oauth` tokens are auto-refreshed via the standard OAuth 2.0 `refresh_token` grant. This is the only way to authenticate MCP servers.
- **Environment variables** (`environment_variable`) — keyed by `secret_name` (the env var name). The sandbox sees only an **opaque placeholder**; the real secret is substituted into the outbound request **at egress**. Use this for any service that authenticates through an environment variable: CLIs (`aws`, `gcloud`, `stripe`), SDKs, or direct `curl` calls from the `bash` tool.

Secret fields you supply (`token`, `access_token`, `refresh_token`, `client_secret`, `secret_value`) are write-only — never returned in API responses.

#### Credentials and the sandbox

Vaults store credentials; those credentials **never enter the sandbox**. This is a deliberate security boundary — code running in the sandbox (including anything the agent writes) cannot read or exfiltrate a vaulted credential, even under prompt injection. Instead, credentials are injected by Anthropic-side proxies **after** a request leaves the sandbox:

- **MCP tool calls** are routed through an Anthropic-side proxy that fetches the credential from the vault and adds it to the outbound request.
- **Git operations on attached GitHub repositories** (`git pull`, `git push`, GitHub REST calls) are routed through a git proxy that injects the `github_repository` resource's `authorization_token` the same way.
- **Environment-variable credentials** appear in the sandbox as an opaque placeholder; the real value replaces the placeholder at egress, on requests to the credential's allowed hosts only.

**When vault credentials don't fit** (e.g. self-hosted sandboxes — `environment_variable` is not yet supported there), **register a custom tool:** the agent emits `agent.custom_tool_use`, your orchestrator (which already holds the credential) executes the call and returns `user.custom_tool_result` over the same authenticated event stream. No public endpoint is exposed; the sandbox never sees the secret. See `shared/managed-agents-client-patterns.md` → Pattern 9.

**Do not put API keys in the system prompt or user messages as a workaround** — they persist in the session's event history.

> Formerly known internally as TATs (Tool/Tenant Access Tokens).

**Flow:**

1. Create a vault (`client.beta.vaults.create(...)`) — one per tenant/user, or one shared, depending on your model
2. Add credentials to it (`client.beta.vaults.credentials.create(...)`) — MCP credentials are keyed by MCP server URL; environment-variable credentials by `secret_name`
3. Reference the vault on session create via `vault_ids: ["vlt_..."]`
4. Anthropic auto-refreshes OAuth tokens before they expire and substitutes secrets at runtime

**MCP OAuth credential shape**:

```json
{
  "display_name": "Notion (workspace-foo)",
  "auth": {
    "type": "mcp_oauth",
    "mcp_server_url": "https://mcp.notion.com/mcp",
    "access_token": "<current access token>",
    "expires_at": "2026-04-02T14:00:00Z",
    "refresh": {
      "refresh_token": "<refresh token>",
      "client_id": "<your OAuth client_id>",
      "token_endpoint": "https://api.notion.com/v1/oauth/token",
      "token_endpoint_auth": { "type": "none" }
    }
  }
}
```

The `refresh` block is what enables auto-refresh — `token_endpoint` is where Anthropic posts the `refresh_token` grant. `token_endpoint_auth` is a discriminated union:

| `type` | Shape | Use when |
|---|---|---|
| `"none"` | `{type: "none"}` | Public OAuth client (no secret) |
| `"client_secret_basic"` | `{type: "client_secret_basic", client_secret: "..."}` | Confidential client, secret via HTTP Basic auth |
| `"client_secret_post"` | `{type: "client_secret_post", client_secret: "..."}` | Confidential client, secret in request body |

Omit `refresh` entirely if you only have an access token with no refresh capability — it'll work until it expires, then the agent loses access.

> 💡 **Getting an OAuth token.** How you obtain the initial access and refresh tokens depends on the MCP server — consult its documentation. Once you have them, store them in a vault credential using the shape above; Anthropic auto-refreshes via the `refresh.token_endpoint` from there.

**Environment-variable credential shape**:

```json
{
  "display_name": "Twilio API key for sandbox",
  "auth": {
    "type": "environment_variable",
    "secret_name": "TWILIO_API_KEY",
    "secret_value": "sk-your-secret-here",
    "networking": {
      "type": "limited",
      "allowed_hosts": ["api.twilio.com", "*.twilio.com"]
    }
  }
}
```

`networking.allowed_hosts` controls which outbound hosts the secret can be substituted for — `{"type": "limited", "allowed_hosts": [...]}` or `{"type": "unrestricted"}` if you can't enumerate the domains in advance. Limiting is strongly recommended: it prevents the key from ever being sent to unauthorized hosts.

> ⚠️ **Two networking layers, both required.** `networking.allowed_hosts` on the credential controls which requests *use the secret*, not which requests are *allowed*. The agent must also be able to reach the domain at the **environment level** (`unrestricted`, or the host listed in the environment's `allowed_hosts` — see `shared/managed-agents-environments.md`). A domain missing from either layer means the secret-substituted request fails.

> ⚠️ **Client-side validation caveat.** Substitution happens at egress, not inside the sandbox — clients that validate the credential *format* locally before making a network request (e.g. a CLI that checks the key starts with `sk-`) will see the opaque placeholder and may fail at startup. If a client rejects the credential before any network call, that's why.

> 💡 **Scope the key minimally.** The agent can do anything the key allows; a key with broader permissions than the task needs increases the blast radius if the agent behaves unexpectedly.

**Not supported with self-hosted sandboxes** — `environment_variable` credentials require Anthropic-managed egress. See `shared/managed-agents-self-hosted-sandboxes.md`.

**Constraints (all credential types):**

- **Unique key per vault.** `mcp_server_url` (MCP credentials) and `secret_name` (environment-variable credentials) must be unique among active credentials in a vault; duplicates return a 409.
- **Keys are immutable.** Secret values and `display_name` can be updated (rotation); to change `mcp_server_url`, `secret_name`, `token_endpoint`, or `client_id`, archive the credential and create a new one. Archiving purges the secret and frees the key for a replacement.
- **Maximum 20 credentials per vault.**
- Credentials are stored as provided and **not validated until session runtime** — an invalid credential surfaces as an authentication or downstream error during the session, which is emitted but does not block the session from continuing.

**Scoping:** Vaults are workspace-scoped. Anyone with developer+ role in the API workspace can create, read (metadata only — secrets are write-only), and attach vaults. `vault_ids` can be set at session **create** time but not via session update (the SDK docstring says "Not yet supported; requests setting this field are rejected").

---

## Skills

Skills are reusable, filesystem-based resources that provide your agent with domain-specific expertise: workflows, context, and best practices that transform general-purpose agents into specialists. Unlike prompts (conversation-level instructions for one-off tasks), skills load on-demand and eliminate the need to repeatedly provide the same guidance across multiple conversations.

Two types — both work the same way; the agent automatically uses them when relevant to the task at hand:

| Type | What it is |
|---|---|
| **Pre-built Anthropic skills** | Common document tasks (PowerPoint, Excel, Word, PDF). Reference by name (e.g. `xlsx`). |
| **Custom skills** | Skills you've created in your organization via the Skills API. Reference by `skill_id` + optional `version`. |

**Max 20 skills per agent.** Agent creation uses `managed-agents-2026-04-01`; the separate Skills API (for managing custom skill definitions) uses `skills-2025-10-02`.

### Enabling skills on a session

Skills are attached to the **agent** definition via `agents.create()`:

```ts
const agent = await client.beta.agents.create(
  {
    name: "Financial Agent",
    model: "claude-opus-4-8",
    system: "You are a financial analysis agent.",
    skills: [
      { type: "anthropic", skill_id: "xlsx" },
      { type: "custom", skill_id: "skill_abc123", version: "latest" },
    ],
  }
);
```

Python:

```python
agent = client.beta.agents.create(
    name="Financial Agent",
    model="claude-opus-4-8",
    system="You are a financial analysis agent.",
    skills=[
        {"type": "anthropic", "skill_id": "xlsx"},
        {"type": "custom", "skill_id": "skill_abc123", "version": "latest"},
    ]
)
```

**Skill reference fields:**

| Field | Anthropic skill | Custom skill |
|---|---|---|
| `type` | `"anthropic"` | `"custom"` |
| `skill_id` | Skill name (e.g. `"xlsx"`, `"docx"`, `"pptx"`, `"pdf"`) | Skill ID from Skills API (e.g. `"skill_abc123"`) |
| `version` | — | `"latest"` or a specific version number |

### Skills API

| Operation             | Method   | Path                                            |
| --------------------- | -------- | ----------------------------------------------- |
| Create Skill          | `POST`   | `/v1/skills`                                    |
| List Skills           | `GET`    | `/v1/skills`                                    |
| Get Skill             | `GET`    | `/v1/skills/{id}`                               |
| Delete Skill          | `DELETE` | `/v1/skills/{id}`                               |
| Create Version        | `POST`   | `/v1/skills/{id}/versions`                      |
| List Versions         | `GET`    | `/v1/skills/{id}/versions`                      |
| Get Version           | `GET`    | `/v1/skills/{id}/versions/{version}`            |
| Delete Version        | `DELETE` | `/v1/skills/{id}/versions/{version}`            |


FILE:shared/managed-agents-webhooks.md
# Managed Agents — Webhooks

Anthropic can POST to your HTTPS endpoint when a Managed Agents resource changes state — an alternative to holding an SSE stream or polling. Payloads are **thin** (event type + resource IDs only); on receipt, fetch the resource for current state. Every delivery is HMAC-signed.

> **Direction matters.** This page covers *Anthropic → you* notifications about session/vault state. It does **not** cover *third-party → you* webhooks that *trigger* a session (e.g. a GitHub push handler that calls `sessions.create()`) — that's ordinary application code on your side with no Anthropic-specific wire format.

---

## Register an endpoint (Console only)

Console → **Manage → Webhooks**. There is no programmatic endpoint-management API yet. Secret rotation is supported from the same page.

| Field | Constraint |
|---|---|
| URL | HTTPS on port 443, publicly resolvable hostname |
| Event types | Subscribe per `data.type` — you only receive subscribed types (plus test events) |
| Signing secret | `whsec_`-prefixed, 32 bytes, **shown once at creation** — store it |

---

## Verify the signature

Every delivery is HMAC-signed. **Use the SDK's `client.beta.webhooks.unwrap()`** — it verifies the signature, rejects payloads more than ~5 minutes old, and returns the parsed event. It reads the `whsec_` secret from `ANTHROPIC_WEBHOOK_SIGNING_KEY`.

```python
import anthropic
from flask import Flask, request

client = anthropic.Anthropic()  # reads ANTHROPIC_WEBHOOK_SIGNING_KEY from env
app = Flask(__name__)


@app.route("/webhook", methods=["POST"])
def webhook():
    try:
        event = client.beta.webhooks.unwrap(
            request.get_data(as_text=True),
            headers=dict(request.headers),
        )
    except Exception:
        return "invalid signature", 400

    if event.id in seen_event_ids:  # dedupe retries — id is per-event, not per-delivery
        return "", 204
    seen_event_ids.add(event.id)

    match event.data.type:
        case "session.status_idled":
            session = client.beta.sessions.retrieve(event.data.id)
            notify_user(session)
        case "vault_credential.refresh_failed":
            alert_oncall(event.data.id)

    return "", 204
```

Pass the **raw request body** to `unwrap()` — frameworks that re-serialize JSON (Express `.json()`, Flask `.get_json()`) change the bytes and break the MAC. For other languages, look up the `beta.webhooks.unwrap` binding in the SDK repo (`shared/live-sources.md`); don't hand-roll verification.

---

## Payload envelope

```json
{
  "type": "event",
  "id": "event_01ABC...",
  "created_at": "2026-03-18T14:05:22Z",
  "data": {
    "type": "session.status_idled",
    "id": "session_01XYZ...",
    "organization_id": "8a3d2f1e-...",
    "workspace_id": "c7b0e4d9-..."
  }
}
```

Switch on `data.type`, fetch the resource by `data.id`, return any **2xx** to acknowledge. `created_at` is when the *state transition* happened, not when the webhook fired.

---

## Supported `data.type` values

| `data.type` | Fires when |
|---|---|
| `session.status_scheduled` | Session created and ready to accept events |
| `session.status_run_started` | Agent execution kicked off (every transition to `running`) |
| `session.status_idled` | Agent awaiting input (tool approval, custom tool result, or next message) |
| `session.status_terminated` | Session hit a terminal error |
| `session.thread_created` | Multiagent: coordinator opened a new subagent thread |
| `session.thread_idled` | Multiagent: a subagent thread is waiting for input |
| `session.outcome_evaluation_ended` | Outcome grader finished one iteration |
| `vault.archived` | Vault was archived |
| `vault.created` | Vault was created |
| `vault.deleted` | Vault was deleted |
| `vault_credential.archived` | Vault credential was archived |
| `vault_credential.created` | Vault credential was created |
| `vault_credential.deleted` | Vault credential was deleted |
| `vault_credential.refresh_failed` | MCP OAuth vault credential failed to refresh |

> These are **webhook** `data.type` values — a separate namespace from SSE event types (`session.status_idle`, `span.outcome_evaluation_end`, etc. in `shared/managed-agents-events.md`). Don't reuse SSE constants in webhook handlers.

---

## Delivery behavior & pitfalls

- **No ordering guarantee.** `session.status_idled` may arrive before `session.outcome_evaluation_ended` even if the evaluation finished first. Sort by envelope `created_at` if order matters.
- **Retries carry the same `event.id`.** At least one retry on non-2xx. Dedupe on `event.id`.
- **3xx is failure.** Redirects are not followed — update the URL in Console if your endpoint moves.
- **Auto-disable** after ~20 consecutive failed deliveries, or immediately if the hostname resolves to a private IP or returns a redirect. Re-enable manually in Console.
- **Thin payload is intentional.** Don't expect `stop_reason`, `outcome_evaluations`, credential secrets, etc. on the webhook body — fetch the resource.

FILE:shared/model-migration.md
# Model Migration Guide

> **If you arrived via `/claude-api migrate`:** this is the right file. Execute the steps below in order — do not summarize them back to the user. Start with Step 0 (confirm scope) before touching any file.

How to move existing code to newer Claude models. Covers breaking changes, deprecated parameters, and drop-in replacements for retired models.

For the latest, authoritative version (with code samples in every supported language), WebFetch the **Migration Guide** URL from `shared/live-sources.md`. Use this file for the consolidated, skill-resident reference; fall back to the live docs whenever a model launch or breaking change may have shifted the picture.

**This file is large.** Use the section names below to jump (or `Grep` this file for the heading text). Read Step 0 and Step 1 first — they apply to every migration. Then read only the per-target section for the model you are migrating to.

| Section | When you need it |
|---|---|
| Step 0: Confirm the migration scope | Always — before any edits |
| Step 1: Classify each file | Always — decides whether to swap, add-alongside, or skip |
| Per-SDK Syntax Reference | Translate the Python examples in this guide to TypeScript / Go / Ruby / Java / C# / PHP |
| Destination Models / Retired Model Replacements | Picking a target model |
| Breaking Changes by Source Model | Migrating to Opus 4.6 / Sonnet 4.6 |
| Migrating to Opus 4.7 | Migrating to Opus 4.7 (breaking changes, silent defaults, behavioral shifts) |
| Opus 4.7 Migration Checklist | The required vs optional items for 4.7, tagged `[BLOCKS]` / `[TUNE]` |
| Migrating to Opus 4.8 | Migrating to Opus 4.8 (no new breaking changes; mid-session system prompts; behavioral re-tuning) |
| Opus 4.8 Migration Checklist | The required vs optional items for 4.8, tagged `[BLOCKS]` / `[TUNE]` |
| Migrating to Claude Fable 5 | Migrating to Claude Fable 5 or Claude Mythos 5 (always-on protected thinking, new tokenizer, refusal handling, data retention, behavioral shifts + prompting guidance) |
| Claude Fable 5 Migration Checklist | The required vs optional items for Claude Fable 5, tagged `[BLOCKS]` / `[TUNE]` |
| Verify the Migration | After edits — runtime spot-check |

**TL;DR:** Change the model ID string. If you were using `budget_tokens`, switch to `thinking: {type: "adaptive"}`. If you were using assistant prefills, they 400 on both Opus 4.6 and Sonnet 4.6 — switch to one of the prefill replacements (most often `output_config.format`; see the table in Breaking Changes by Source Model). If you're moving from Sonnet 4.5 to Sonnet 4.6, set `effort` explicitly — 4.6 defaults to `high`. Remove the `effort-2025-11-24` and `fine-grained-tool-streaming-2025-05-14` beta headers (GA on 4.6); remove `interleaved-thinking-2025-05-14` once you're on adaptive thinking (keep it only while using the transitional `budget_tokens` escape hatch). Then drop back from `client.beta.messages.create` to `client.messages.create`. Dial back any aggressive "CRITICAL: YOU MUST" tool instructions; 4.6 follows the system prompt much more closely.

---

## Step 0: Confirm the migration scope

**Before any Write, Edit, or MultiEdit call, confirm the scope.** If the user's request does not explicitly name a single file, a specific directory, or an explicit file list, **ask first — do not start editing**. This is non-negotiable: even imperative-sounding requests like "migrate my codebase", "move my project to X", "upgrade to Sonnet 4.6", or bare "migrate to Opus 4.7" leave the scope ambiguous and require a clarifying question. Phrases like "my project", "my code", "my codebase", "the whole thing", "everywhere", or "across the repo" are **ambiguous, not directive** — they tell you *what* to do but not *where*. Ask before doing.

Offer the common scopes explicitly and wait for the answer before touching any file:

1. The entire working directory
2. A specific subdirectory (e.g. `src/`, `app/`, `services/billing/`)
3. A specific file or a list of files

Surface this as a single clarifying question so the user can answer in one turn. **Proceed without asking only when the scope is already unambiguous** — the user named an exact file ("migrate `extract.py` to Sonnet 4.6"), pointed at a specific directory ("migrate everything under `services/billing/` to Opus 4.6"), listed specific files ("update `a.py` and `b.py`"), or already answered the scope question in an earlier turn. If you can answer the question "which files is this change going to touch?" with a precise list from the prompt alone, proceed. If not, ask.

**Worked example.** If the user says *"Move my project to Opus 4.6. I want adaptive thinking everywhere it makes sense."* you do not know whether "my project" means the whole working directory, just `src/`, just the production code, or something else — the `everywhere` makes the intent clear (update every call site *within scope*) but the scope itself is still not defined. Do not start editing. Respond with:

> Before I start editing, can you confirm the scope? I can migrate:
> 1. Every `.py` file in the working directory
> 2. Just the files under `src/` (production code)
> 3. A specific subdirectory or list of files you name
>
> Which one?

Then wait for the answer. The same applies to *"Migrate to Opus 4.7"* and bare *"Help me upgrade to Sonnet 4.6"* — ask before editing.

**Sizing the scope question (large repos).** Before asking, get a per-directory count so the user can pick concretely:

```sh
rg -l "<old-model-id>" --type-not md | cut -d/ -f1 | sort | uniq -c | sort -rn
```

Present the breakdown in your scope question (e.g. *"Found 217 references across 3 directories: api/ (130), api-go/ (62), routing/ (25). Which to migrate?"*). Also confirm `git status` is clean before surveying — unexpected modifications mean a concurrent process; stop and investigate before proceeding.

---

## Step 1: Classify each file

Not every file that contains the old model ID is a **caller** of the API. Before editing, classify each file into one of these buckets — the right action differs:

| # | Bucket | What it looks like | Action |
|---|---|---|---|
| 1 | **Calls the API/SDK** | `client.messages.create(model=…)`, `anthropic.Anthropic()`, request payloads | Swap the model ID **and** apply the breaking-change checklist for the target version (below). |
| 2 | **Defines or serves the model** | Model registries, OpenAPI specs, routing/queue configs, model-policy enums, generated catalogs | The old entry **stays** (the model is still served). Ask whether to (a) add the new model alongside, (b) leave alone, or (c) retire the old model — never blind-replace. **If you can't ask, default to (a): add the new model alongside and flag it** — replacing would de-register a model that's still in production. |
| 3 | **References the ID as an opaque string** | UI fallback constants, capability-gate substring checks, generic test fixtures, label parsers, env defaults | Usually swap the string and verify any parser/regex/substring match handles the new ID — but check the sub-cases below first. |
| 4 | **Suffixed variant ID** | `claude-<model>-<suffix>` like `-fast`, `-1024k`, `-200k`, `[1m]`, dated snapshots | These are deployment/routing identifiers, not the public model ID. **Do not assume a new-model equivalent exists.** Verify in the registry first; if absent, leave the string alone and flag it. |

**Bucket 3 sub-cases — before swapping a string reference, check:**

- **Capability gate** (e.g. `if 'opus-4-6' in model_id:` enables a feature) → **add the new ID alongside**, don't replace. The old model is still served and still has the capability, so replacing would silently disable the feature for any old-model traffic that still flows through. If you know no old-model traffic will hit this gate (single-caller codebase fully migrating), replacing is fine; if unsure, add alongside.
- **Registry-assert test** (e.g. `assert "claude-X" in supported_models`, `test_X_has_N_clusters`) → **add an assertion for the new model alongside; keep the old one.** The old model is still served, so its assertion stays valid — but the registry should also include the new model, so assert that too. Heuristic: if the test references multiple model versions in a list, it's a registry test; if one model in a struct compared only to itself, it's a generic fixture.
- **Frozen / generated snapshot** → **regenerate**, don't hand-edit.
- **Coupled to a definer** (e.g. an integration test that passes model authorization via a shared `conftest` seed list, or asserts on a billing-tier / rate-limit-group enum or a generated SKU/pricing catalog) → **verify the definer has a new-model entry first.** If not, add a seed entry (reusing the nearest existing tier as a placeholder); if you can't confidently do that, ask the user how to populate the definer. **Do not skip the test.** Swapping without populating the definer will make the test fail at runtime.

When migrating tests specifically: breaking parameters (`temperature`, `top_p`, `budget_tokens`) are usually absent — test fixtures rarely set sampling params on placeholder models. The breaking-change scan is still required, but expect mostly clean results.

**Find intentionally-flagged sync points first.** Many codebases tag spots that must change at every model launch with comment markers like `MODEL LAUNCH`, `KEEP IN SYNC`, `@model-update`, or similar. Grep for whatever convention the repo uses *before* the broad model-ID grep — those markers point at the load-bearing changes.

---

## Per-SDK Syntax Reference

Code examples in this guide are Python. **The same fields exist in every official Anthropic SDK** — Stainless generates all 7 from the same OpenAPI spec, so JSON field names map 1:1 with only case-convention differences. Use the rows below to translate the Python examples to the SDK you are migrating.

> **Verify type and method names against the SDK source before writing them into customer code.** WebFetch the relevant repository from the SDK source-code table in `shared/live-sources.md` (one row per SDK) and confirm the exact symbol — particularly for typed SDKs (Go, Java, C#) where union/builder names can differ from the JSON shape. Do not guess type names that aren't in the table below or in `<lang>/claude-api/README.md`.

<!-- The rows below were verified against each SDK's `synced/model-launch-april` branch. -->

### `thinking` — `budget_tokens` → adaptive

| SDK | Before | After |
|---|---|---|
| Python | `thinking={"type": "enabled", "budget_tokens": N}` | `thinking={"type": "adaptive"}` |
| TypeScript | `thinking: { type: 'enabled', budget_tokens: N }` | `thinking: { type: 'adaptive' }` |
| Go | `Thinking: anthropic.ThinkingConfigParamOfEnabled(N)` | `Thinking: anthropic.ThinkingConfigParamUnion{OfAdaptive: &anthropic.ThinkingConfigAdaptiveParam{}}` |
| Ruby | `thinking: { type: "enabled", budget_tokens: N }` | `thinking: { type: "adaptive" }` |
| Java | `.thinking(ThinkingConfigEnabled.builder().budgetTokens(N).build())` | `.thinking(ThinkingConfigAdaptive.builder().build())` |
| C# | `Thinking = new ThinkingConfigEnabled { BudgetTokens = N }` | `Thinking = new ThinkingConfigAdaptive()` |
| PHP | `thinking: ['type' => 'enabled', 'budget_tokens' => N]` | `thinking: ['type' => 'adaptive']` |

### Sampling parameters — `temperature` / `top_p` / `top_k`

(Remove the field entirely on Opus 4.7; on Claude 4.x keep at most one of `temperature` or `top_p`.)

| SDK | Field(s) to remove |
|---|---|
| Python | `temperature=…`, `top_p=…`, `top_k=…` |
| TypeScript | `temperature: …`, `top_p: …`, `top_k: …` |
| Go | `Temperature: anthropic.Float(…)`, `TopP: anthropic.Float(…)`, `TopK: anthropic.Int(…)` |
| Ruby | `temperature: …`, `top_p: …`, `top_k: …` |
| Java | `.temperature(…)`, `.topP(…)`, `.topK(…)` |
| C# | `Temperature = …`, `TopP = …`, `TopK = …` |
| PHP | `temperature: …`, `topP: …`, `topK: …` |

### Prefill replacement — structured outputs via `output_config.format`

| SDK | Remove (last assistant turn) | Add |
|---|---|---|
| Python | `{"role": "assistant", "content": "…"}` | `output_config={"format": {"type": "json_schema", "schema": SCHEMA}}` |
| TypeScript | `{ role: 'assistant', content: '…' }` | `output_config: { format: { type: 'json_schema', schema: SCHEMA } }` |
| Go | trailing `anthropic.MessageParam{Role: "assistant", …}` | `OutputConfig: anthropic.OutputConfigParam{Format: anthropic.JSONOutputFormatParam{…}}` |
| Ruby | `{ role: "assistant", content: "…" }` | `output_config: { format: { type: "json_schema", schema: SCHEMA } }` |
| Java | trailing `Message.builder().role(ASSISTANT)…` | `.outputConfig(OutputConfig.builder().format(JsonOutputFormat.builder()…build()).build())` |
| C# | trailing `new Message { Role = "assistant", … }` | `OutputConfig = new OutputConfig { Format = new JsonOutputFormat { … } }` |
| PHP | trailing `['role' => 'assistant', 'content' => '…']` | `outputConfig: ['format' => ['type' => 'json_schema', 'schema' => $SCHEMA]]` |

### `thinking.display` — opt back into summarized reasoning (Opus 4.7)

| SDK | Add |
|---|---|
| Python | `thinking={"type": "adaptive", "display": "summarized"}` |
| TypeScript | `thinking: { type: 'adaptive', display: 'summarized' }` |
| Go | `Thinking: anthropic.ThinkingConfigParamUnion{OfAdaptive: &anthropic.ThinkingConfigAdaptiveParam{Display: anthropic.ThinkingConfigAdaptiveDisplaySummarized}}` |
| Ruby | `thinking: { type: "adaptive", display: "summarized" }` (or `display_:` when constructing the model class directly) |
| Java | `.thinking(ThinkingConfigAdaptive.builder().display(ThinkingConfigAdaptive.Display.SUMMARIZED).build())` |
| C# | `Thinking = new ThinkingConfigAdaptive { Display = Display.Summarized }` |
| PHP | `thinking: ['type' => 'adaptive', 'display' => 'summarized']` |

For any field not in these tables, the JSON key in the Python example translates directly: `snake_case` for Python/TypeScript/Ruby, `camelCase` named args for PHP, `PascalCase` struct fields for Go/C#, `camelCase` builder methods for Java.

---

## Explain every change you make

Migration edits often look arbitrary to a user who hasn't read the release notes — a removed `temperature`, a deleted prefill, a rewritten system-prompt sentence. **For each edit, tell the user what you changed and why**, tied to the specific API or behavioral change that motivates it. Do this in your summary as you work, not just at the end.

Be especially explicit about **system-prompt edits**. Users are rightly protective of their prompts, and prompt-tuning changes are judgment calls (not hard API requirements). For any prompt edit:

- Quote the before and after text.
- State the behavioral shift that motivates it (e.g. *"Opus 4.7 calibrates response length to task complexity, so I added an explicit length instruction"*, or *"4.6 follows instructions more literally, so 'CRITICAL: YOU MUST use the search tool' will now overtrigger — softened to 'Use the search tool when…'"*).
- Make clear which prompt edits are **optional tuning** (tone, length, subagent guidance) versus which code edits are **required to avoid a 400** (sampling params, `budget_tokens`, prefills). Never present an optional prompt change as mandatory.

If you're applying several prompt-tuning edits at once, offer them as a short list the user can accept or decline item-by-item rather than silently rewriting their system prompt.

---

## Before You Migrate

1. **Confirm the target model ID.** Use only the exact strings from `shared/models.md` — do not append date suffixes to aliases (`claude-opus-4-6`, not `claude-opus-4-6-20251101`). Guessing an ID will 404.
2. **Check which features your code uses** with this checklist:
   - `thinking: {type: "enabled", budget_tokens: N}` → migrate to adaptive thinking on Opus 4.6 / Sonnet 4.6 (still functional but deprecated)
   - Assistant-turn prefills (`messages` ending with `role: "assistant"`) → must change on Opus 4.6 / Sonnet 4.6 (returns 400)
   - `output_format` parameter on `messages.create()` → must change on all models (deprecated API-wide)
   - `max_tokens > ~16000` → must stream on any model (above ~16K risks SDK HTTP timeouts). When streaming, Sonnet 4.6 / Haiku 4.5 cap at 64K and Opus 4.6 caps at 128K
   - Beta headers `effort-2025-11-24`, `fine-grained-tool-streaming-2025-05-14`, `interleaved-thinking-2025-05-14` → GA on 4.6, remove them and switch from `client.beta.messages.create` to `client.messages.create`
   - Moving Sonnet 4.5 → Sonnet 4.6 with no `effort` set → 4.6 defaults to `high`, which may change your latency/cost profile
   - System prompts with `CRITICAL`, `MUST`, `If in doubt, use X` language → likely to overtrigger on 4.6 (see Prompt-Behavior Changes)
   - Coming from 3.x / 4.0 / 4.1: also check sampling params (`temperature` + `top_p`), tool versions (`text_editor_20250728`), `refusal` + `model_context_window_exceeded` stop reasons, trailing-newline tool-param handling
3. **Test on a single request first.** Run one call against the new model, inspect the response, then roll out.

---

## Destination Models (recommended targets)

| If you're on…                         | Migrate to         | Why                                               |
| ------------------------------------- | ------------------ | ------------------------------------------------- |
| Claude Mythos Preview (`claude-mythos-preview`) | `claude-mythos-5` (Project Glasswing successor) or `claude-fable-5` (GA) | Same tokenizer family — mostly a model-ID swap; remove `thinking` config and prefill; see Migrating to Claude Fable 5 |
| Opus 4.7                              | `claude-opus-4-8`  | Most capable Opus-tier model; same API surface as 4.7 (no new breaking changes) — mostly prompt re-tuning; see Migrating to Opus 4.8 |
| Opus 4.6                              | `claude-opus-4-8`  | Apply the Opus 4.7 breaking changes, then the 4.8 re-tuning |
| Opus 4.0 / 4.1 / 4.5 / Opus 3         | `claude-opus-4-8`  | Apply 4.6 → 4.7 → 4.8 in order (adaptive thinking, drop sampling params, then re-tune) |
| Sonnet 4.0 / 4.5 / 3.7 / 3.5          | `claude-sonnet-4-6`| Best speed / intelligence balance; adaptive thinking; 64K output |
| Haiku 3 / 3.5                         | `claude-haiku-4-5` | Fastest and most cost-effective                   |

Default to the latest Opus for the caller's tier unless they explicitly chose otherwise. The Opus migrations layer: if you're on Opus 4.6 or older, apply each version's section in order up to your target (e.g. 4.5 → 4.8 means the 4.6, 4.7, and 4.8 sections in sequence). A 4.7 → 4.8 move has no new breaking changes — see Migrating to Opus 4.8 below.

---

## Retired Model Replacements

These models return 404 — update immediately:

| Retired model                 | Retired       | Drop-in replacement  |
| ----------------------------- | ------------- | -------------------- |
| `claude-3-7-sonnet-20250219`  | Feb 19, 2026  | `claude-sonnet-4-6`  |
| `claude-3-5-haiku-20241022`   | Feb 19, 2026  | `claude-haiku-4-5`   |
| `claude-3-opus-20240229`      | Jan 5, 2026   | `claude-opus-4-8`    |
| `claude-3-5-sonnet-20241022`  | Oct 28, 2025  | `claude-sonnet-4-6`  |
| `claude-3-5-sonnet-20240620`  | Oct 28, 2025  | `claude-sonnet-4-6`  |
| `claude-3-sonnet-20240229`    | Jul 21, 2025  | `claude-sonnet-4-6`  |
| `claude-2.1`, `claude-2.0`    | Jul 21, 2025  | `claude-sonnet-4-6`  |

## Deprecated Models (retiring soon)

| Model                         | Retires       | Replacement          |
| ----------------------------- | ------------- | -------------------- |
| `claude-3-haiku-20240307`     | Apr 19, 2026  | `claude-haiku-4-5`   |
| `claude-opus-4-20250514`      | June 15, 2026 | `claude-opus-4-8`    |
| `claude-sonnet-4-20250514`    | June 15, 2026 | `claude-sonnet-4-6`  |

---

## Breaking Changes by Source Model

### Migrating from Sonnet 4.5 to Sonnet 4.6 (effort default change)

Sonnet 4.5 had no `effort` parameter; Sonnet 4.6 defaults to `high`. If you just switch the model string and do nothing else, you may see noticeably higher latency and token usage. Set `effort` explicitly.

**Recommended starting points:**

| Workload                                          | Start at       | Notes                                                                                                    |
| ------------------------------------------------- | -------------- | -------------------------------------------------------------------------------------------------------- |
| Chat, classification, content generation          | `low`          | With `thinking: {"type": "disabled"}` you'll see similar or better performance vs. Sonnet 4.5 no-thinking |
| Most applications (balanced)                      | `medium`       | The default sweet spot for quality vs. cost                                                              |
| Agentic coding, tool-heavy workflows              | `medium`       | Pair with adaptive thinking and a generous `max_tokens` (up to 64K with streaming — Sonnet 4.6's ceiling) |
| Autonomous multi-step agents, long-horizon loops  | `high`         | Scale down to `medium` if latency/tokens become a concern                                                 |
| Computer-use agents                               | `high` + adaptive | Sonnet 4.6's best computer-use accuracy is on adaptive + high                                          |

For non-thinking chat workloads specifically:

```python
client.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=8192,
    thinking={"type": "disabled"},
    output_config={"effort": "low"},
    messages=[{"role": "user", "content": "..."}],
)
```

**When to use Opus 4.6 instead:** hardest and longest-horizon problems — large code migrations, deep research, extended autonomous work. Sonnet 4.6 wins on fast turnaround and cost efficiency.

### Migrating to Opus 4.6 / Sonnet 4.6 (from any older model)

**1. Manual extended thinking is deprecated — use adaptive thinking.**

`thinking: {type: "enabled", budget_tokens: N}` (manual extended thinking with a fixed token budget) is deprecated on Opus 4.6 and Sonnet 4.6. Replace it with `thinking: {type: "adaptive"}`, which lets Claude decide when and how much to think. Adaptive thinking also enables interleaved thinking automatically (no beta header needed).

```python
# Old (still works on older models, deprecated on 4.6)
response = client.messages.create(
    model="claude-sonnet-4-5",
    max_tokens=16000,
    thinking={"type": "enabled", "budget_tokens": 8000},
    messages=[...]
)

# New (Opus 4.6 / Sonnet 4.6)
response = client.messages.create(
    model="claude-opus-4-6",  # or "claude-sonnet-4-6"
    max_tokens=16000,
    thinking={"type": "adaptive"},
    output_config={"effort": "high"},  # optional: low | medium | high | max
    messages=[...]
)
```

Adaptive thinking is the long-term target, and on internal evaluations it outperforms manual extended thinking. Move when you can.

**Transitional escape hatch:** manual extended thinking is still *functional* on Opus 4.6 and Sonnet 4.6 (deprecated, will be removed in a future release). If you need a hard ceiling while migrating — for example, to bound token spend on a runaway workload before you've tuned `effort` — you can keep `budget_tokens` around alongside an explicit `effort` value, then remove it in a follow-up. `budget_tokens` must be strictly less than `max_tokens`:

```python
# Transitional only — deprecated, plan to remove
client.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=16384,
    thinking={"type": "enabled", "budget_tokens": 8192},  # must be < max_tokens
    output_config={"effort": "medium"},
    messages=[...],
)
```

If the user asks for a "thinking budget" on 4.6, the preferred answer is `effort` — use `low`, `medium`, `high`, or `max` (Opus-tier only — not Sonnet or Haiku) rather than a token count.

**2. Effort parameter (Opus 4.5, Opus 4.6, Sonnet 4.6 only).**

Controls thinking depth and overall token spend. Goes inside `output_config`, not top-level. Default is `high`. `max` is Opus-tier only (Opus 4.6 and later — not Sonnet or Haiku). Errors on Sonnet 4.5 and Haiku 4.5.

```python
output_config={"effort": "medium"}  # often the best cost / quality balance
```

### Migrating to the 4.6 family (Opus 4.6 and Sonnet 4.6)

**3. Assistant-turn prefills return 400 (Opus 4.6 and Sonnet 4.6).**

Prefilled responses on the final assistant turn are no longer supported on either Opus 4.6 or Sonnet 4.6 — both return a 400. Adding assistant messages *elsewhere* in the conversation (e.g., for few-shot examples) still works. Pick the replacement that matches what the prefill was doing:

| Prefill was used for                               | Replacement                                                                                                                               |
| -------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| Forcing JSON / YAML / schema output                | `output_config.format` with a `json_schema` — see example below                                                                           |
| Forcing a classification label                     | Tool with an enum field containing valid labels, or structured outputs                                                                    |
| Skipping preambles (`Here is the summary:\n`)      | System prompt instruction: *"Respond directly without preamble. Do not start with phrases like 'Here is...' or 'Based on...'."*           |
| Steering around bad refusals                       | Usually no longer needed — 4.6 refuses far more appropriately. Plain user-turn prompting is sufficient.                                   |
| Continuing an interrupted response                 | Move continuation into the user turn: *"Your previous response was interrupted and ended with `[last text]`. Continue from there."*     |
| Injecting reminders / context hydration            | Inject into the user turn instead. For complex agent harnesses, expose context via a tool call or during compaction.                      |

```python
# Old (fails on Opus 4.6 / Sonnet 4.6) — prefill forcing JSON shape
messages=[
    {"role": "user", "content": "Extract the name."},
    {"role": "assistant", "content": "{\"name\": \""},
]

# New — structured outputs replace the prefill
response = client.messages.create(
    model="claude-opus-4-6",
    max_tokens=1024,
    output_config={"format": {"type": "json_schema", "schema": {...}}},
    messages=[{"role": "user", "content": "Extract the name."}],
)
```

**4. Stream for `max_tokens > ~16K` (all models); Opus 4.6 alone reaches 128K.**

Non-streaming requests hit SDK HTTP timeouts at high `max_tokens`, regardless of model — stream for anything above ~16K output. The streamable ceiling differs by model: Sonnet 4.6 and Haiku 4.5 cap at 64K, and Opus 4.6 alone goes up to 128K.

```python
with client.messages.stream(model="claude-opus-4-6", max_tokens=64000, ...) as stream:
    message = stream.get_final_message()
```

**5. Tool-call JSON escaping may differ (Opus 4.6 and Sonnet 4.6).**

Both 4.6 models can produce tool call `input` fields with Unicode or forward-slash escaping. Always parse with `json.loads()` / `JSON.parse()` — never raw-string-match the serialized input.

### All models

**6. `output_format` → `output_config.format` (API-wide).**

The old top-level `output_format` parameter on `messages.create()` is deprecated. Use `output_config.format` instead. This is not 4.6-specific — applies to every model.

---

## Beta Headers to Remove on 4.6

Several beta headers that were required on 4.5 are now GA on 4.6 and should be removed. Leaving them in is harmless but misleading; removing them also lets you move from `client.beta.messages.create(...)` back to `client.messages.create(...)`.

| Header                                    | Status on 4.6                                              | Action                                                  |
| ----------------------------------------- | ---------------------------------------------------------- | ------------------------------------------------------- |
| `effort-2025-11-24`                       | Effort parameter is GA                                     | Remove                                                  |
| `fine-grained-tool-streaming-2025-05-14`  | GA                                                         | Remove                                                  |
| `interleaved-thinking-2025-05-14`         | Adaptive thinking enables interleaved thinking automatically | Remove when using adaptive thinking; still functional on Sonnet 4.6 *with* manual extended thinking, but that path is deprecated |
| `token-efficient-tools-2025-02-19`        | Built in to all Claude 4+ models                           | Remove (no effect)                                      |
| `output-128k-2025-02-19`                  | Built in to Claude 4+ models                               | Remove (no effect)                                      |

Once you remove all of these and finish moving to adaptive thinking, you can switch the SDK call site from the beta namespace back to the regular one:

```python
# Before
response = client.beta.messages.create(
    model="claude-opus-4-5",
    betas=["interleaved-thinking-2025-05-14", "effort-2025-11-24"],
    ...
)

# After
response = client.messages.create(
    model="claude-opus-4-6",
    thinking={"type": "adaptive"},
    output_config={"effort": "high"},
    ...
)
```

---

## Additional Changes When Coming from 3.x / 4.0 / 4.1 → 4.6

If you're jumping from Opus 4.1, Sonnet 4, Sonnet 3.7, or an older Claude 3.x model directly to 4.6, apply everything above *plus* the items in this section. Users already on Opus 4.5 / Sonnet 4.5 can skip this.

**1. Sampling parameters: `temperature` OR `top_p`, not both.**

Passing both will error on every Claude 4+ model:

```python
# Old (3.x only — errors on 4+)
client.messages.create(temperature=0.7, top_p=0.9, ...)

# New
client.messages.create(temperature=0.7, ...)  # or top_p, not both
```

**2. Update tool versions.**

Legacy tool versions are not supported on 4+. **Both the `type` and the `name` field change** — `text_editor_20250728` and `str_replace_based_edit_tool` are a pair; updating one without the other 400s. Also remove the `undo_edit` command from your text-editor integration:

| Old                                               | New                                                     |
| ------------------------------------------------- | ------------------------------------------------------- |
| `text_editor_20250124` + `str_replace_editor`     | `text_editor_20250728` + `str_replace_based_edit_tool`  |
| `code_execution_*` (earlier versions)             | `code_execution_20250825`                               |
| `undo_edit` command                               | *(no longer supported — delete call sites)*             |

```python
# Before
tools = [{"type": "text_editor_20250124", "name": "str_replace_editor"}]

# After — BOTH fields change
tools = [{"type": "text_editor_20250728", "name": "str_replace_based_edit_tool"}]
```

**3. Handle the `refusal` stop reason.**

Claude 4+ can return `stop_reason: "refusal"` on the response. If your code only handles `end_turn` / `tool_use` / `max_tokens`, add a branch:

```python
if response.stop_reason == "refusal":
    # Surface the refusal to the user; do not retry with the same prompt
    ...
```

**4. Handle the `model_context_window_exceeded` stop reason (4.5+).**

Distinct from `max_tokens`: it means the model hit the *context window* limit, not the requested output cap. Handle both:

```python
if response.stop_reason == "model_context_window_exceeded":
    # Context window exhausted — compact or split the conversation
    ...
elif response.stop_reason == "max_tokens":
    # Requested output cap hit — retry with higher max_tokens or stream
    ...
```

**5. Trailing newlines preserved in tool call string parameters (4.5+).**

4.5 and 4.6 preserve trailing newlines that older models stripped. If your tool implementations do exact string matching against tool-call `input` values (e.g., `if name == "foo"`), verify they still match when the model sends `"foo\n"`. Normalizing with `.rstrip()` on the receiving side is usually the simplest fix.

**6. Haiku: rate limits reset between generations.**

Haiku 4.5 has its own rate-limit pool separate from Haiku 3 / 3.5. If you're ramping traffic as you migrate, check your tier's Haiku 4.5 limits at [API rate limits](https://platform.claude.com/docs/en/api/rate-limits) — a quota that comfortably served Haiku 3.5 traffic may need a tier bump for the same volume on 4.5.

---

## Prompt-Behavior Changes (Opus 4.5 / 4.6, Sonnet 4.6)

These don't break your code, but prompts that worked on 4.5-and-earlier may over- or under-trigger on 4.6. Tune as needed.

**1. Aggressive instructions cause overtriggering.** Opus 4.5 and 4.6 follow the system prompt much more closely than earlier models. Prompts written to *overcome* the old reluctance are now too aggressive:

| Before (worked on 4.0 / 4.5)                | After (use on 4.6)                        |
| ------------------------------------------- | ----------------------------------------- |
| `CRITICAL: You MUST use this tool when...`  | `Use this tool when...`                   |
| `Default to using [tool]`                   | `Use [tool] when it would improve X`      |
| `If in doubt, use [tool]`                   | *(delete — no longer needed)*             |

If the model is now overtriggering a tool or skill, the fix is almost always to dial back the language, not to add more guardrails.

**2. Overthinking and excessive exploration (Opus 4.6).** At higher `effort` settings, Opus 4.6 explores more before answering. If that burns too many thinking tokens, lower `effort` first (`medium` is often the sweet spot) before adding prose instructions to constrain reasoning.

**3. Overeager subagent spawning (Opus 4.6).** Opus 4.6 has a strong preference for delegating to subagents. If you see it spawning a subagent for something a direct `grep` or `read` would solve, add guidance: *"Use subagents only for parallel or independent workstreams. For single-file reads or sequential operations, work directly."*

**4. Overengineering (Opus 4.5 / 4.6).** Both models may add extra files, abstractions, or defensive error handling beyond what was asked. If you want minimal changes, prompt for it explicitly: *"Only make changes directly requested. Don't add helpers, abstractions, or error handling for scenarios that can't happen."*

**5. LaTeX math output (Opus 4.6).** Opus 4.6 defaults to LaTeX (`\frac{}{}`, `$...$`) for math and technical content. If you need plain text, instruct it explicitly: *"Format all math as plain text — no LaTeX, no `$`, no `\frac{}{}`. Use `/` for division and `^` for exponents."*

**6. Skipped verbal summaries (4.6 family).** The 4.6 models are more concise and may skip the summary paragraph after a tool call, jumping straight to the next action. If you rely on those summaries for visibility, add: *"After completing a task that involves tool use, provide a brief summary of what you did."*

**7. "Think" as a trigger word (Opus 4.5 with thinking disabled).** When `thinking` is off, Opus 4.5 is particularly sensitive to the word *think* and may reason more than you want. Use `consider`, `evaluate`, or `reason through` instead.

---

## Model-ID Rename Quick Reference

| Old string (migration source)  | New string         |
| ------------------------------ | ------------------ |
| `claude-opus-4-7`              | `claude-opus-4-8`  |
| `claude-opus-4-6`              | `claude-opus-4-8`  |
| `claude-opus-4-5`              | `claude-opus-4-8`  |
| `claude-opus-4-1`              | `claude-opus-4-8`  |
| `claude-opus-4-0`              | `claude-opus-4-8`  |
| `claude-mythos-preview`        | `claude-mythos-5` (Project Glasswing) or `claude-fable-5` |
| `claude-sonnet-4-5`            | `claude-sonnet-4-6`|
| `claude-sonnet-4-0`            | `claude-sonnet-4-6`|

Older aliases (`claude-opus-4-7`, `claude-opus-4-6`, `claude-opus-4-5`, `claude-sonnet-4-5`, etc.) are still active and can be pinned if you need time before upgrading — see `shared/models.md` for the full legacy list.

### Amazon Bedrock model IDs

If the code uses the `AnthropicBedrockMantle` client (Python `anthropic[bedrock]`, TypeScript `@anthropic-ai/bedrock-sdk`, Java `BedrockMantleBackend`, Go `bedrock.NewMantleClient`, etc.) or targets `https://bedrock-mantle.{region}.api.aws/anthropic`, it is running on **Claude in Amazon Bedrock**. All breaking changes in this guide apply unchanged there — it serves the same Messages API shape — but model IDs carry an `anthropic.` provider prefix:

| First-party ID | Bedrock ID |
|---|---|
| `claude-opus-4-8` | `anthropic.claude-opus-4-8` |
| `claude-opus-4-7` | `anthropic.claude-opus-4-7` |
| `claude-haiku-4-5` | `anthropic.claude-haiku-4-5` |

When migrating a Bedrock file, apply the same rename-table row as first-party, then keep/add the `anthropic.` prefix. Do **not** generate a first-party `claude-*` ID for a Bedrock client — it will 400.

**Skip for Bedrock:** the `code_execution_*` tool-version checklist item and the **Task Budgets** section — both are first-party-only features (Bedrock does not support server-side Anthropic tools or the `task-budgets-2026-03-13` beta). Everything else in this guide — `effort`, adaptive/extended thinking, `output_config.format`, `thinking.display`, fine-grained tool streaming, token counting — is available on Bedrock.

> **Out of scope:** the legacy Amazon Bedrock integration (`InvokeModel` / `Converse` APIs with ARN-versioned IDs like `anthropic.claude-3-5-sonnet-20241022-v2:0`) uses a different request shape and model-ID format. This guide does not cover it; WebFetch the Bedrock page in `shared/live-sources.md` if the user is migrating between the two Bedrock integrations.

### Claude Platform on AWS

If the code uses `AnthropicAWS` / `AnthropicAws` / `anthropicaws.NewClient` / `AnthropicAwsClient` (or targets `https://aws-external-anthropic.{region}.api.aws`), it is running on **Claude Platform on AWS** — Anthropic-operated, same-day API parity. Model IDs are **bare first-party** strings; apply the rename table above **verbatim** and every breaking-change section in this guide unchanged. There is nothing to skip. Do **not** add an `anthropic.` prefix (that's Amazon Bedrock, a separate offering). See `shared/claude-platform-on-aws.md` for client/auth details.

---

## Migration Checklist

Every item is tagged: **`[BLOCKS]`** items cause a 400 error, infinite loop, silent timeout, or wrong tool selection if missed — apply these as code edits, not as suggestions. **`[TUNE]`** items are quality/cost adjustments.

For each file that calls `messages.create()` / equivalent SDK method:

- [ ] **[BLOCKS]** Update the `model=` string to the new alias
- [ ] **[BLOCKS]** Replace `budget_tokens` with `thinking={"type": "adaptive"}` (deprecated on Opus 4.6 / Sonnet 4.6)
- [ ] **[BLOCKS]** Move `format` from top-level `output_format` into `output_config.format`
- [ ] **[BLOCKS]** Remove any assistant-turn prefills if targeting Opus 4.6 or Sonnet 4.6 (see the prefill replacement table)
- [ ] **[BLOCKS]** Switch to streaming if `max_tokens > ~16000` (otherwise SDK HTTP timeout)
- [ ] **[TUNE]** Verify tool-input handling parses JSON rather than raw-string-matching the serialized input (4.6 may escape Unicode / forward slashes differently; most SDKs already expose `block.input` as a parsed object)
- [ ] **[TUNE]** Set `output_config={"effort": "..."}` explicitly — especially when moving Sonnet 4.5 → Sonnet 4.6 (4.6 defaults to `high`)
- [ ] **[TUNE]** Remove GA beta headers: `effort-2025-11-24`, `fine-grained-tool-streaming-2025-05-14`, `token-efficient-tools-2025-02-19`, `output-128k-2025-02-19`; remove `interleaved-thinking-2025-05-14` once on adaptive thinking
- [ ] **[TUNE]** Switch `client.beta.messages.create(...)` → `client.messages.create(...)` once all betas are removed
- [ ] **[TUNE]** Review system prompt for aggressive tool language (`CRITICAL:`, `MUST`, `If in doubt`) and dial it back

**Extra items when coming from 3.x / 4.0 / 4.1:**
- [ ] **[BLOCKS]** Remove either `temperature` or `top_p` (passing both 400s on Claude 4+)
- [ ] **[BLOCKS]** Update text-editor tool `type` to `text_editor_20250728`
- [ ] **[BLOCKS]** Update text-editor tool `name` to `str_replace_based_edit_tool` — **changing only the `type` and keeping `name: "str_replace_editor"` returns a 400**
- [ ] **[BLOCKS]** Update code-execution tool to `code_execution_20250825`
- [ ] **[BLOCKS]** Delete any `undo_edit` command call sites
- [ ] **[TUNE]** Add handling for `stop_reason == "refusal"`
- [ ] **[TUNE]** Add handling for `stop_reason == "model_context_window_exceeded"` (4.5+)
- [ ] **[TUNE]** Verify tool-param string matching tolerates trailing newlines (preserved on 4.5+)
- [ ] **[TUNE]** If moving to Haiku 4.5: review rate-limit tier (separate pool from Haiku 3.x)

**Verification:**
- [ ] Run one test request and inspect `response.stop_reason`, `response.usage`, and whether tool-use / thinking behavior matches expectations

For cached prompts: the render order and hash inputs did not change, so existing `cache_control` breakpoints keep working. However, **changing the model string invalidates the existing cache** — the first request on the new model will write the cache fresh.

---

## Migrating to Opus 4.7

> **Model ID `claude-opus-4-7` is authoritative as written here.** When the user asks to migrate to Opus 4.7, write `model="claude-opus-4-7"` exactly. Do **not** WebFetch to verify — this guide is the source of truth for migration target IDs. The corresponding entry exists in `shared/models.md`.

Claude Opus 4.7 was Anthropic's most capable model at its launch and is now the previous-generation Opus (Opus 4.8 is current — see Migrating to Opus 4.8 below). It is highly autonomous and performs exceptionally well on long-horizon agentic work, knowledge work, vision tasks, and memory tasks. This section summarizes everything that was new at the 4.7 launch and remains the layered breaking-change path for callers coming from Opus 4.6 or older. It is layered on top of the 4.6 migration above — if the caller is jumping from Opus 4.5 or older, apply the 4.6 changes first, then this section, then the 4.8 section.

**TL;DR for someone already on Opus 4.6:** update the model ID to `claude-opus-4-7`, strip any remaining `budget_tokens` and sampling parameters (both 400 on Opus 4.7), give `max_tokens` extra headroom and re-baseline with `count_tokens()` against the new model, opt back into `thinking.display: "summarized"` if reasoning is surfaced to users, and re-tune `effort` — it matters more on 4.7 than on any prior Opus.

### Breaking changes (will 400 on Opus 4.7)

**Extended thinking removed.**

`thinking: {type: "enabled", budget_tokens: N}` is no longer supported on Claude Opus 4.7 or later models and returns a 400 error. Switch to adaptive thinking (`thinking: {type: "adaptive"}`) and use the effort parameter to control thinking depth. Adaptive thinking is **off by default** on Claude Opus 4.7: requests with no `thinking` field run without thinking, matching Opus 4.6 behavior. Set `thinking: {type: "adaptive"}` explicitly to enable it.

```python
# Before (Opus 4.6)
client.messages.create(
    model="claude-opus-4-6",
    max_tokens=64000,
    thinking={"type": "enabled", "budget_tokens": 32000},
    messages=[{"role": "user", "content": "..."}],
)

# After (Opus 4.7)
client.messages.create(
    model="claude-opus-4-7",
    max_tokens=64000,
    thinking={"type": "adaptive"},
    output_config={"effort": "high"},  # or "max", "xhigh", "medium", "low"
    messages=[{"role": "user", "content": "..."}],
)
```

If the caller wasn't using extended thinking, no change is required — thinking is off by default, or can be set explicitly with `thinking={"type": "disabled"}`.

Delete `budget_tokens` plumbing entirely. For the replacement `effort` value, see **Choosing an effort level on Opus 4.7** below — there is no exact 1:1 mapping from `budget_tokens`.

**Sampling parameters removed.**

The `temperature`, `top_p`, and `top_k` parameters are no longer accepted on Claude Opus 4.7. Requests that include them return a 400 error. Remove these fields from your request payloads. Prompting is the recommended way to guide model behavior on Claude Opus 4.7. If you were using `temperature = 0` for determinism, note that it never guaranteed identical outputs on prior models.

```python
# Before — errors on Opus 4.7
client.messages.create(temperature=0.7, top_p=0.9, ...)

# After
client.messages.create(...)  # no sampling params
```

- **If the intent was determinism** — use `effort: "low"` with a tighter prompt.
- **If the intent was creative variance** — the prompt replacement depends on the use case; **ask the user** how they want variance elicited. If you can't ask, add a use-case-appropriate instruction along the lines of *"choose something off-distribution and interesting"* — e.g. for text generation, *"Vary your phrasing and structure across responses"*; for frontend/design, use the propose-4-directions approach under **Design and frontend coding** below.

### Choosing an effort level on Opus 4.7

`budget_tokens` controlled how much to *think*; `effort` controls how much to think *and* act, so there is no exact 1:1 mapping. **Use `xhigh` for best results in coding and agentic use cases, and a minimum of `high` for most intelligence-sensitive use cases.** Experiment with other levels to further tune token usage and intelligence:

| Level | Use when | Notes |
| --- | --- | --- |
| `max` | Intelligence-demanding tasks worth testing at the ceiling | Can deliver gains in some use cases but may show diminishing returns from increased token usage; can be prone to overthinking |
| `xhigh` | **Most coding and agentic use cases** | The best setting for these; used as the default in Claude Code |
| `high` | Intelligence-sensitive use cases generally | Balances token usage and intelligence; recommended minimum for most intelligence-sensitive work |
| `medium` | Cost-sensitive use cases that need to reduce token usage while trading off intelligence | |
| `low` | Short, scoped tasks and latency-sensitive workloads that are not intelligence-sensitive | |

### Silent default changes (no error, but behavior differs)

**Thinking content omitted by default.**

Thinking blocks still appear in the response stream on Claude Opus 4.7, but their `thinking` field is empty unless you explicitly opt in. This is a silent change from Claude Opus 4.6, where the default was to return summarized thinking text. To restore summarized thinking content on Claude Opus 4.7, set `thinking.display` to `"summarized"`. **The block-field name is unchanged** — it is still `block.thinking` on a `thinking`-type block; do not rename it.

**Detect this:** any code that reads `block.thinking` (or equivalent) from a `thinking`-type block and renders it in a UI, log, or trace. **The fix is the request parameter, not the response handling** — add `display: "summarized"` to the `thinking` parameter:

```python
thinking={"type": "adaptive", "display": "summarized"}  # "display" is new on Opus 4.7; values: "omitted" (default) | "summarized"
```

The default is `"omitted"` on Claude Opus 4.7. If thinking content was never surfaced anywhere, no change needed. If your product streams reasoning to users, the new default appears as a long pause before output begins; set `display: "summarized"` to restore visible progress during thinking.

**Updated token counting.**

Claude Opus 4.7 and Claude Opus 4.6 count tokens differently. The same input text produces a higher token count on Claude Opus 4.7 than on Claude Opus 4.6, and `/v1/messages/count_tokens` will return a different number of tokens for Claude Opus 4.7 than it did for Claude Opus 4.6. The token efficiency of Claude Opus 4.7 can vary by workload shape. Prompting interventions, `task_budget`, and `effort` can help control costs and ensure appropriate token usage. Keep in mind that these controls may trade off model intelligence. **Update your `max_tokens` parameters to give additional headroom, including compaction triggers.** Claude Opus 4.7 provides a 1M context window at standard API pricing with no long-context premium.

What else to check:

- Client-side token estimators (tiktoken-style approximations) calibrated against 4.6
- Cost calculators that multiply tokens by a fixed per-token rate
- Rate-limit retry thresholds keyed to measured token counts

Re-baseline by re-running `client.messages.count_tokens()` against `claude-opus-4-7` on a representative sample of the caller's prompts. Do not apply a blanket multiplier. For cost-sensitive workloads, consider reducing `effort` by one level (e.g. `high` → `medium`). For agentic loops, consider adopting Task Budgets (below).

### New feature: Task Budgets (beta)

Opus 4.7 introduces **task budgets** — tell Claude how many tokens it has for a full agentic loop (thinking + tool calls + final output). The model sees a running countdown and uses it to prioritize work and wrap up gracefully as the budget is consumed.

This is a **suggestion the model is aware of**, not a hard cap. It is distinct from `max_tokens`, which remains the enforced per-response limit and is *not* surfaced to the model. Use `task_budget` when you want the model to self-moderate; use `max_tokens` as a hard ceiling to cap usage.

Requires beta header `task-budgets-2026-03-13`:

```python
client.beta.messages.create(
    betas=["task-budgets-2026-03-13"],
    model="claude-opus-4-7",
    max_tokens=64000,
    thinking={"type": "adaptive"},
    output_config={
        "effort": "high",
        "task_budget": {"type": "tokens", "total": 128000},
    },
    messages=[...],
)
```

Set a generous budget for open-ended agentic tasks and tighten it for latency-sensitive ones. **Minimum `task_budget.total` is 20,000 tokens.** If the budget is too restrictive for the task, the model may complete it less thoroughly, referencing its budget as the constraint. **Do not add `task_budget` during a migration unless you are sure the budget value is right** — if you can run the workload and measure, do so; otherwise ask the user for the value rather than guessing. This is the primary lever for offsetting the token-counting shift on agentic workloads.

### Capability improvements

**High-resolution vision.** Opus 4.7 is the first Claude model with high-resolution image support. Maximum image resolution is **2576 pixels on the long edge** (up from 1568px on Opus 4.6 and prior). This unlocks gains on vision-heavy workloads, especially computer use and screenshot/artifact/document understanding. Coordinates returned by the model now map 1:1 to actual image pixels, so no scale-factor math is needed.

High-res support is **automatic on Opus 4.7** — no beta header, no client-side opt-in required. The model accepts larger inputs and returns pixel-accurate coordinates out of the box.

**Token cost.** Full-resolution images on Opus 4.7 can use up to ~3× more image tokens than on prior models (up to ~4784 tokens per image, vs. the previous ~1,600-token cap). If the extra fidelity isn't needed, downsample client-side before sending to control cost — but **do not add downsampling by default during a migration**. If you're not sure whether the pipeline needs the fidelity, ask the user rather than guessing. Use `count_tokens()` on representative images on Opus 4.7 to re-baseline before reacting to any measured cost shift.

Beyond resolution, Opus 4.7 also improves on low-level perception (pointing, measuring, counting) and natural-image bounding-box localization and detection.

**Knowledge work.** Meaningful gains on tasks where the model visually verifies its own output — `.docx` redlining, `.pptx` editing, and programmatic chart/figure analysis (e.g. pixel-level data transcription via image-processing libraries). If prompts have scaffolding like *"double-check the slide layout before returning"*, try removing it and re-baselining.

**Memory.** Opus 4.7 is better at writing and using file-system-based memory. If an agent maintains a scratchpad, notes file, or structured memory store across turns, that agent should improve at jotting down notes to itself and leveraging its notes in future tasks.

**User-facing progress updates.** Opus 4.7 provides more regular, higher-quality interim updates during long agentic traces. If the system prompt has scaffolding like *"After every 3 tool calls, summarize progress"*, try removing it to avoid excessive user-facing text. If the length or contents of Opus 4.7's updates are not well-calibrated to your use case, explicitly describe what these updates should look like in the prompt and provide examples.

### Real-time cybersecurity safeguards

Requests that involve prohibited or high-risk topics may lead to refusals.

### Fast Mode: not available on Opus 4.7

Opus 4.7 does not have a Fast Mode variant. **Opus 4.6 Fast remains supported**. Only surface this if the caller's code actually uses a Fast Mode model string (e.g. `claude-opus-4-6-fast`); if the word "fast" does not appear in the code, say nothing about Fast Mode.

When you see `model="claude-opus-4-6-fast"` (or similar), **the migration edit is**:

```python
# Opus 4.7 has no Fast Mode — keeping on 4.6 Fast (caller's choice to switch to standard Opus 4.7).
model="claude-opus-4-6-fast",
```

That is: leave the model string **unchanged**, add the comment above it, and tell the user their two options — (a) stay on Opus 4.6 Fast, which remains supported, or (b) move latency-tolerant traffic to standard Opus 4.7 for the intelligence gain. Do **not** rewrite the model string to `claude-opus-4-7` yourself; that silently trades latency for intelligence, which is the caller's decision.

### Behavioral shifts (prompt-tunable)

These don't break anything, but prompts tuned for Opus 4.6 may land differently. Opus 4.7 is more steerable than 4.6, so small prompt nudges usually close the gap.

**More literal instruction following.** Claude Opus 4.7 interprets prompts more literally and explicitly than Claude Opus 4.6, particularly at lower effort levels. It will not silently generalize an instruction from one item to another, and it will not infer requests you didn't make. The upside of this literalism is precision and less thrash. It generally performs better for API use cases with carefully tuned prompts, structured extraction, and pipelines where you want predictable behavior. A prompt and harness review may be especially helpful for migration to Claude Opus 4.7.

**Verbosity calibrates to task complexity.** Opus 4.7 scales response length to how complex it judges the task to be, rather than defaulting to a fixed verbosity — shorter answers on simple lookups, much longer on open-ended analysis. If the product depends on a particular length or style, tune the prompt explicitly. To reduce verbosity:

> *"Provide concise, focused responses. Skip non-essential context, and keep examples minimal."*

If you see specific kinds of over-verbosity (e.g. over-explaining), add instructions targeting those. Positive examples showing the desired level of concision tend to be more effective than negative examples or instructions telling the model what not to do. Do **not** assume existing "be concise" instructions should be removed — test first.

**Tone and writing style.** Opus 4.7 is more direct and opinionated, with less validation-forward phrasing and fewer emoji than Opus 4.6's warmer style. As with any new model, prose style on long-form writing may shift. If the product relies on a specific voice, re-evaluate style prompts against the new baseline. If a warmer or more conversational voice is wanted, specify it:

> *"Use a warm, collaborative tone. Acknowledge the user's framing before answering."*

**`effort` matters more than on any prior Opus.** Opus 4.7 respects `effort` levels more strictly, especially at the low end. At `low` and `medium` it scopes work to what was asked rather than going above and beyond — good for latency and cost, but on moderate tasks at `low` there is some risk of under-thinking.

- If shallow reasoning shows up on complex problems, raise `effort` to `high` or `xhigh` rather than prompting around it.
- If `effort` must stay `low` for latency, add targeted guidance: *"This task involves multi-step reasoning. Think carefully through the problem before responding."*
- **At `xhigh` or `max`, set a large `max_tokens`** so the model has room to think and act across tool calls and subagents. Start at 64K and tune from there. (`xhigh` is a new effort level on Opus 4.7, between `high` and `max`.)

Adaptive-thinking triggering is also steerable. If the model thinks more often than wanted — which can happen with large or complex system prompts — add: *"Thinking adds latency and should only be used when it will meaningfully improve answer quality — typically for problems that require multi-step reasoning. When in doubt, respond directly."*

**Uses tools less often by default.** Opus 4.7 tends to use tools less often than 4.6 and to use reasoning more. This produces better results in most cases, but for products that rely on tools (search/retrieval, function-calling, computer-use steps), it can drop tool-use rate. Two levers:

- **Raise `effort`** — `high` or `xhigh` show substantially more tool usage in agentic search and coding, and are especially useful for knowledge work.
- **Prompt for it** — be explicit in tool descriptions or the system prompt about when and how to use the tool, and encourage the model to err on the side of using it more often:

> *"When the answer depends on information not present in the conversation, you MUST call the `search` tool before answering — do not answer from prior knowledge."*

**Fewer subagents by default.** Opus 4.7 tends to spawn fewer subagents than 4.6. This is steerable — give explicit guidance on when delegation is desirable. For a coding agent, for example:

> *"Do NOT spawn a subagent for work you can complete directly in a single response (e.g. refactoring a function you can already see). Spawn multiple subagents in the same turn when fanning out across items or reading multiple files."*

**Design and frontend coding.** Opus 4.7 has stronger design instincts than 4.6, with a consistent default house style: warm cream/off-white backgrounds (around `#F4F1EA`), serif display type (Georgia, Fraunces, Playfair), italic word-accents, and a terracotta/amber accent. This reads well for editorial, hospitality, and portfolio briefs, but will feel off for dashboards, dev tools, fintech, healthcare, or enterprise apps — and it appears in slide decks as well as web UIs.

The default is persistent. Generic instructions ("don't use cream," "make it clean and minimal") tend to shift the model to a different fixed palette rather than producing variety. Two approaches work reliably:

1. **Specify a concrete alternative.** The model follows explicit specs precisely — give exact hex values, typefaces, and layout constraints.
2. **Have the model propose options before building.** This breaks the default and gives the user control:

   > *"Before building, propose 4 distinct visual directions tailored to this brief (each as: bg hex / accent hex / typeface — one-line rationale). Ask the user to pick one, then implement only that direction."*

If the caller previously relied on `temperature` for design variety, use approach (2) — it produces meaningfully different directions across runs.

Opus 4.7 also requires less frontend-design prompting than previous models to avoid generic "AI slop" aesthetics. Where earlier models needed a lengthy anti-slop snippet, Opus 4.7 generates distinctive, creative frontends with a much shorter nudge. This snippet works well alongside the variety approaches above:

> *"NEVER use generic AI-generated aesthetics like overused font families (Inter, Roboto, Arial, system fonts), cliched color schemes (particularly purple gradients on white or dark backgrounds), predictable layouts and component patterns, and cookie-cutter design that lacks context-specific character. Use unique fonts, cohesive colors and themes, and animations for effects and micro-interactions."*

**Interactive coding products.** Opus 4.7's token usage and behavior can differ between autonomous, asynchronous coding agents with a single user turn and interactive, synchronous coding agents with multiple user turns. Specifically, it tends to use more tokens in interactive settings, primarily because it reasons more after user turns. This can improve long-horizon coherence, instruction following, and coding capabilities in long interactive coding sessions, but also comes with more token usage. To maximize both performance and token efficiency in coding products, use `effort: "xhigh"` or `"high"`, add autonomous features (like an auto mode), and reduce the number of human interactions required from users.

When limiting required user interactions, specify the task, intent, and relevant constraints upfront in the first human turn. Well-specified, clear, and accurate task descriptions upfront help maximize autonomy and intelligence while minimizing extra token usage after user turns — because Opus 4.7 is more autonomous than prior models, this usage pattern helps to maximize performance. In contrast, ambiguous or underspecified prompts conveyed progressively over multiple user turns tend to reduce token efficiency and sometimes performance.

**Code review.** Opus 4.7 is meaningfully better at finding bugs than prior models, with both higher recall and precision. However, if a code-review harness was tuned for an earlier model, it may initially show *lower* recall — this is likely a harness effect, not a capability regression. When a review prompt says "only report high-severity issues," "be conservative," or "don't nitpick," Opus 4.7 follows that instruction more faithfully than earlier models did: it investigates just as thoroughly, identifies the bugs, and then declines to report findings it judges to be below the stated bar. Precision rises, but measured recall can fall even though underlying bug-finding has improved.

Recommended prompt language:

> *"Report every issue you find, including ones you are uncertain about or consider low-severity. Do not filter for importance or confidence at this stage — a separate verification step will do that. Your goal here is coverage: it is better to surface a finding that later gets filtered out than to silently drop a bug. For each finding, include your confidence level and an estimated severity so a downstream filter can rank them."*

This can be used without an actual second step, but moving confidence filtering out of the finding step often helps. If the harness has a separate verification/dedup/ranking stage, tell the model explicitly that its job at the finding stage is coverage, not filtering. If single-pass self-filtering is wanted, be concrete about the bar rather than using qualitative terms like "important" — e.g. *"report any bugs that could cause incorrect behavior, a test failure, or a misleading result; only omit nits like pure style or naming preferences."* Iterate on prompts against a subset of evals to validate recall or F1 gains.

**Computer use.** Computer use works across resolutions up to the new 2576px / 3.75MP maximum. Sending images at **1080p** provides a good balance of performance and cost. For particularly cost-sensitive workloads, **720p** or **1366×768** are lower-cost options with strong performance. Test to find the ideal settings for the use case; experimenting with `effort` can also help tune behavior.

---

## Opus 4.7 Migration Checklist

Every item is tagged: **`[BLOCKS]`** items cause a 400 error, infinite loop, silent truncation, or empty output if missed — apply these as code edits, not as suggestions. **`[TUNE]`** items are quality/cost adjustments — surface them to the user as recommendations.

`[BLOCKS]` items prefixed with **"If…"** or **"At…"** are conditional. Before working through the list, **scan the file** for the conditions: does it surface thinking text to a UI/log? Does it set `output_config.effort` to `"x-high"` or `"max"`? Is it a security workload? Is it a multi-turn agentic loop? Apply only the items whose condition matches.

- [ ] **[BLOCKS]** Replace `thinking: {type: "enabled", budget_tokens: N}` with `thinking: {type: "adaptive"}` + `output_config.effort`; delete `budget_tokens` plumbing entirely
- [ ] **[BLOCKS]** Strip `temperature`, `top_p`, `top_k` from request construction
- [ ] **[BLOCKS]** If thinking content is surfaced to users or stored in logs: add `thinking.display: "summarized"` (otherwise the rendered text is empty)
- [ ] **[BLOCKS]** At `output_config.effort` of `xhigh` or `max`: set `max_tokens` ≥ 64000 (otherwise output truncates mid-thought)
- [ ] **[TUNE]** Give `max_tokens` and compaction triggers extra headroom; re-run `count_tokens()` against `claude-opus-4-7` on representative prompts to re-baseline (no blanket multiplier)
- [ ] **[TUNE]** Re-baseline cost and rate-limit dashboards *before* reacting to measured shifts
- [ ] **[TUNE]** Re-evaluate `effort` per route — use `xhigh` for coding/agentic and a minimum of `high` for most intelligence-sensitive work; it matters more on 4.7 than any prior Opus
- [ ] **[TUNE]** Multi-turn agentic loops: adopt the API-native Task Budgets (`output_config.task_budget`, beta `task-budgets-2026-03-13`, minimum 20k tokens) — this is for capping *cumulative* spend across a loop; per-turn depth is `effort`
- [ ] **[TUNE]** Check for ambiguous or underspecified instructions that relied on 4.6 generalizing intent, and update them to be clearer or more precise — 4.7 follows them literally
- [ ] **[TUNE]** Tool-use workloads: add explicit when/how-to-use guidance to tool descriptions (4.7 reaches for tools less often)
- [ ] **[TUNE]** Verbosity: test existing length instructions before changing them — 4.7 calibrates length to task complexity, so tune for the desired output rather than assuming a direction
- [ ] **[TUNE]** Remove forced-progress-update scaffolding (*"after every N tool calls…"*)
- [ ] **[TUNE]** Remove knowledge-work verification scaffolding (*"double-check the slide layout…"*) and re-baseline
- [ ] **[TUNE]** Add tone instruction if a warmer / more conversational voice is needed; re-evaluate style prompts on writing-heavy routes
- [ ] **[TUNE]** Subagent tool present: add explicit spawn / don't-spawn guidance
- [ ] **[TUNE]** Frontend/design output: specify a concrete palette/typeface, or have the model propose 4 visual directions before building (the default cream/serif house style is persistent)
- [ ] **[TUNE]** Interactive coding products: use `effort: "xhigh"` or `"high"`, add autonomous features (e.g. an auto mode) to reduce human interactions, and specify task/intent/constraints upfront in the first turn
- [ ] **[TUNE]** Code-review harnesses: remove or loosen "only report high-severity" / "be conservative" filters and have the model report every finding with confidence + severity; move filtering to a downstream step (4.7 follows severity filters more literally, which can depress measured recall)
- [ ] **[TUNE]** Vision-heavy pipelines (screenshots, charts, document understanding): leave images at native resolution up to 2576px long edge for the accuracy gain; remove any scale-factor math from coordinate handling (coords are now 1:1 with pixels). No beta header / opt-in needed — high-res is automatic on Opus 4.7.
- [ ] **[TUNE]** Computer-use pipelines: send screenshots at 1080p for a good performance/cost balance (720p or 1366×768 for cost-sensitive workloads); experiment with `effort` to tune behavior
- [ ] **[TUNE]** Cost-sensitive image pipelines: full-res images on 4.7 use up to ~4784 tokens vs ~1,600 on prior models (~3×). Downsampling client-side before upload avoids the increase, but **do not downsample by default** — if you're unsure whether fidelity is needed, ask the user. Re-baseline with `count_tokens()` on representative images before reacting to cost shifts.

---

## Migrating to Opus 4.8

> **Model ID `claude-opus-4-8` is authoritative as written here.** When the user asks to migrate to Opus 4.8, write `model="claude-opus-4-8"` exactly. Do **not** WebFetch to verify — this guide is the source of truth for migration target IDs. The corresponding entry exists in `shared/models.md`.

Claude Opus 4.8 is our most capable Opus-tier model — highly autonomous, with state-of-the-art long-horizon agentic execution, knowledge work, and memory. It is layered on top of the Opus 4.7 migration above. If the caller is jumping from Opus 4.6 or older, apply the 4.6 and 4.7 sections first, then this one.

**No new breaking changes.** Opus 4.8 keeps the same request surface as Opus 4.7. The same calls that already work on 4.7 work unchanged on 4.8 — adaptive thinking only (`thinking: {type: "enabled", budget_tokens: N}` still 400s; use `{type: "adaptive"}`), sampling parameters (`temperature`, `top_p`, `top_k`) still rejected, last-assistant-turn prefills still 400, `thinking.display` still defaults to `"omitted"`, and the `low`/`medium`/`high`/`xhigh`/`max` effort levels, Task Budgets (beta), and high-resolution vision all behave as on 4.7. A 4.7 → 4.8 migration is therefore **the model-ID swap plus prompt re-tuning** — there is no required code edit beyond the model string.

**TL;DR for someone already on Opus 4.7:** swap the model ID to `claude-opus-4-8`. Nothing else is required to avoid an error. Then re-tune prompts for the behavioral shifts: 4.8 narrates *more* than 4.7 (add a silence-default if you want 4.7-like terseness), writes in a warmer, less hedged voice, is more deliberate and asks more often (add autonomy guidance to claw back ask-rate), and is more conservative about reaching for search, subagents, file-based memory, and custom tools (add explicit "when to use this" triggering). For long-horizon agentic work, give the full task specification up front in one well-specified turn and run at high effort.

### No new API breaking changes (inherited from 4.7)

These all carry over from Opus 4.7 unchanged — apply them only if the caller is coming from Opus 4.6 or earlier (see the **Migrating to Opus 4.7** section above for the before/after and the SDK-specific syntax):

- `thinking: {type: "enabled", budget_tokens: N}` → 400. Use `thinking: {type: "adaptive"}` + `output_config.effort`.
- `temperature`, `top_p`, `top_k` → 400. Remove them; steer with prompting.
- Last-assistant-turn prefills → 400. Use `output_config.format` (structured outputs) or a system-prompt instruction.
- `thinking.display` defaults to `"omitted"`; set `"summarized"` if you surface reasoning to users.

If the caller is already on Opus 4.7 and these are clean, there is nothing to change here.

### New API feature: mid-session system prompts

You can deliver trusted instructions partway through a session by placing `{"role": "system", ...}` entries directly in the `messages` array — without editing the top-level system prompt and invalidating your prompt cache. Use it for things the application learns mid-session: the user delivered async context, a mode toggled (auto-approve enabled), files changed on disk, the remaining token budget dropped.

```python
messages=[
    {"role": "user", "content": [{"type": "tool_result", "tool_use_id": "...", "content": "..."}]},
    {"role": "system", "content": "This project's codebase is Go. Write code in Go."},
]
```

Phrase these as **context, not commands**. State the fact and let Claude act on it; avoid override-style language ("ignore what the user said", "regardless of the user's request", "disregard the previous instruction"). Claude is trained to protect users from instructions that appear to work against them, and that protection applies to the system role too. This is a beta (`anthropic-beta: mid-conversation-system-2026-04-07`) and is available from Opus 4.7 onward, not 4.8-exclusive. For cache-placement details and the older-model `<system-reminder>` fallback, see `shared/prompt-caching.md` and `shared/agent-design.md`.

### Capability improvements

**Long-horizon agentic execution.** Opus 4.8 is state-of-the-art at long, autonomous agentic work — complex refactors and overnight coding runs that complete without human correction. To get the most out of it, **give the full task specification up front in a single well-specified initial turn and run at high effort** (`effort: "high"` or `"xhigh"`). Its long-horizon coherence comes partly from reasoning more at each step; combined with a clear up-front goal, that more-intelligent planning often produces more efficient *and* more accurate output than prior frontier models. The "clear goal up front" principle maps to two product surfaces: in Claude Code, `/goal` sets direction for the run; with **Managed Agents (CMA)**, state what "done" looks like via an **Outcome** (`user.define_outcome` with a gradeable rubric — the harness runs an iterate → grade → revise loop), see `shared/managed-agents-outcomes.md`.

**Effort is a dimension to test, not a fixed setting.** On prior models many reached for `xhigh` reflexively to maximize intelligence. Opus 4.8 has a higher intelligence ceiling, so **start at `high` as the default and iterate** rather than defaulting to `xhigh`. Sweep `medium`, `high`, and `xhigh` on your own eval set and weigh the intelligence ↔ latency ↔ cost tradeoff per route — the relationship isn't monotonic: higher effort up front often *reduces* turn count and total cost on agentic work, while for some tasks `medium` delivers equally good results in less time. Reserve `max` for extremely hard, latency-insensitive cases. The per-level effort table in the **Migrating to Opus 4.7** section above applies unchanged on 4.8.

**Writing voice and clarity.** Testers consistently describe 4.8's prose as clearer, warmer, and less hedged than prior models, with fewer measurable AI vocal tics — especially at higher effort, where it approaches expert-level prose and structure. This is roughly the **opposite** direction from the 4.7 shift (4.7 was more clipped, direct, and less validation-forward). If you added style prompts to counter 4.7's terseness or to inject warmth, re-evaluate them against the new baseline before keeping them — they may now overcorrect. 4.8 is also a stronger thought partner: more thoughtful, more willing to push back, and more likely to infer the right answer from context.

**Code review and debugging.** Stronger real-bug finding and clearer explanations than 4.7 — one-shot fixes where 4.7 needed more, and correctly identifying intermittent flakes rather than declaring "fixed" after one clean run. The 4.7 caveat still applies: if a review harness says "only report high-severity issues" or "be conservative", 4.8 follows it literally and measured recall can drop even though underlying bug-finding improved. Tell the model to report everything and filter downstream (or review a second time) — see the **Code review** guidance in the 4.7 section for the recommended prompt.

### Behavioral shifts (prompt-tunable)

None of these break code, but prompts tuned for Opus 4.7 may land differently. 4.8 follows instructions well, so small, explicit nudges close the gap.

**Tool triggering is surface-dependent (search & knowledge).** 4.8's tool-triggering is more surface-dependent than in prior models: with a system prompt present it is high-precision / low-recall — web search triggers slightly more often but runs fewer rounds per trigger, while knowledge-retrieval tools (Drive, project knowledge, connected files) trigger *less* often. It searches when it's confident search is needed and otherwise answers from context, which can lower research depth on tasks that need it. Recover should-search rate with an explicit search-first instruction:

> ```
> <search_first>
> For questions where current information would change the answer (recent events, current roles or prices, version-specific behavior, or anything the user flags as time-sensitive) search before answering rather than answering from memory. For open-ended research requests, begin searching immediately; do not ask a scoping question first unless the request is genuinely ambiguous about what to research.
> </search_first>
> ```

**Under-utilization of subagents, memory, and custom tools.** Separately from search, 4.8 is conservative about reaching for capabilities that need an explicit "decide to use this" step — file-based memory, subagent delegation, custom tools. It won't reach for complex or expensive capabilities unless reasonably sure they're needed. This is steerable since 4.8 follows instructions well — say *when* each capability applies, not just that it exists:

> *"Before any task longer than a few turns, check your memory file for relevant prior context and write new findings to it as you go. When a task fans out across independent items (many files to read, many tests to run, many candidates to check), delegate to subagents rather than iterating serially."*

The same lever works at the **tool-description** level, not just the system prompt: prescriptive descriptions that state *when* to call a tool (e.g. "Call this when the user asks about current prices or recent events") give meaningful lift on 4.8 over descriptions that only state what the tool does. Make the trigger condition part of each capability's own `description`.

**More user-facing narration.** 4.8 narrates more than 4.7 — more text between tool calls in long tool-calling sessions, and longer, more detailed end-of-task wrap-ups by default. If you previously added scaffolding to force interim status ("after every 3 tool calls, summarize progress"), **remove it** — 4.8 does this on its own. If the narration is too verbose for a coding agent, an explicit silence-default makes it behave like 4.7 with no loss of quality:

> *"Default to silence between tool calls. Only write text when you find something, change direction, or hit a blocker — one sentence each. Do not narrate routine actions ('Now I'll...', 'Let me check...', 'Looking at...'). When done: one or two sentences on the outcome. Do not recap every file or test — the user has been following along."*

For knowledge-work deliverables (reports, analysis readouts), verbosity responds very well to instructions in user preferences or the user turn — expose a verbosity preference rather than hard-coding a length.

**More deliberate — asks more often.** 4.8 is more deliberate than prior Opus models. On minor decisions it would previously just make (a variable name, a default value, which of two equivalent approaches), it tends to pause and ask, and it often closes a completed task with "Want me to also…?" rather than doing the obvious next step or stopping cleanly. This is preferred for high-stakes or unfamiliar codebases, but bugs users when uncalibrated. Grant autonomy on the small stuff while keeping caution where it matters (in Claude Code testing this cut ask-rate by ~12 percentage points with no increase in over-reach):

> *"For minor choices (naming, formatting, default values, which approach among equivalents), pick a reasonable option and note it rather than asking. For scope changes or destructive actions, still ask first."*

**Verbose reasoning when thinking is disabled.** With `thinking: {type: "disabled"}`, 4.8 occasionally writes longer explanations of its reasoning into the visible response, which reads as verbose when the user wants a fast, quick answer. The simplest fix is to leave adaptive thinking on — set `thinking: {type: "adaptive"}` (the recommended setting; it adjusts how much to think per task). Note adaptive is **not** on when the field is omitted — like Opus 4.7, a request with no `thinking` field runs without thinking, so set it explicitly. If you need thinking off for latency or cost, scope it in the system prompt:

> *"Respond only with your final answer. Do not include exploratory reasoning, intermediate drafts, diffs you considered but rejected, or meta-commentary about your process."*

### Opus 4.8 Migration Checklist

Every item is tagged: **`[BLOCKS]`** items cause a 400 error if missed; **`[TUNE]`** items are quality/cost adjustments — surface them to the user as recommendations.

For a caller **already on Opus 4.7**, only the first item is required; everything else is `[TUNE]`. The conditional `[BLOCKS]` item applies only when coming from Opus 4.6 or earlier.

- [ ] **[BLOCKS]** Update the `model=` string to `claude-opus-4-8`
- [ ] **[BLOCKS]** *(only if coming from Opus 4.6 or earlier)* Apply the **Migrating to Opus 4.7** breaking changes first — `budget_tokens` → adaptive thinking, strip `temperature`/`top_p`/`top_k`, remove last-assistant-turn prefills. These already 400 on 4.7 and continue to 400 on 4.8.
- [ ] **[TUNE]** Long-horizon / agentic work: put the full task spec in one well-specified first turn and run at `high` or `xhigh` effort (Claude Code: `/goal`; Managed Agents: an Outcome with a gradeable rubric)
- [ ] **[TUNE]** Effort: sweep `medium` / `high` / `xhigh` on your eval set and pick per route by the intelligence ↔ latency ↔ cost tradeoff (default `high`, `xhigh` for coding/agentic)
- [ ] **[TUNE]** Research depth & tool use: add a search-first instruction; add explicit triggering guidance for subagents, file-based memory, and custom tools (4.8 under-reaches for these by default) — in the system prompt *and* in each tool's own `description` (prescriptive "call this when…" descriptions give measurable lift)
- [ ] **[TUNE]** Narration: remove forced-progress scaffolding (*"after every N tool calls…"*); add a silence-default if a coding agent is too chatty
- [ ] **[TUNE]** Autonomy: add small-decisions-don't-ask guidance to cut ask-rate, while keeping caution on scope changes / destructive actions
- [ ] **[TUNE]** Writing voice: re-evaluate style prompts added to counter 4.7's directness — 4.8 is warmer and less hedged by default; re-baseline before keeping them
- [ ] **[TUNE]** Code-review harnesses: keep the report-everything-filter-downstream pattern (4.8 follows "only high-severity" / "be conservative" filters literally, which can depress measured recall)
- [ ] **[TUNE]** Thinking-disabled paths: add a final-answer-only instruction if reasoning leaks into the visible response
- [ ] **[TUNE]** Consider mid-session system messages (`role:"system"` in `messages`, beta `mid-conversation-system-2026-04-07`) for context the app learns mid-session, instead of rebuilding the top-level system prompt and invalidating the cache

---

## Migrating to Claude Fable 5

> **Model IDs `claude-fable-5` and `claude-mythos-5` are authoritative as written here.** When the user asks to migrate to Claude Fable 5, write `model="claude-fable-5"` exactly; a Mythos Preview migrator in Project Glasswing writes `model="claude-mythos-5"` (everyone else: `claude-fable-5`). Do **not** WebFetch to verify — this guide is the source of truth for migration target IDs. The corresponding entries exist in `shared/models.md`.

Claude Fable 5 is Anthropic's most capable widely released model — for the most demanding reasoning and long-horizon agentic work. **Claude Mythos 5** (`claude-mythos-5`) offers the same capabilities, pricing, and API behavior through Project Glasswing (participation is the only way to access it), and succeeds the invitation-only **Claude Mythos Preview** (`claude-mythos-preview`). Everything in this section applies to both models — only the ID differs. Mythos Preview migrators in Project Glasswing target `claude-mythos-5`; everyone else targets `claude-fable-5`. 1M token context window by default (the maximum is also the default), up to 128K output tokens per request.

**Migrate to Claude Fable 5 only when the user explicitly chose it.** It is not the default Opus upgrade path — pricing is above Opus-tier and the new tokenizer changes cost baselines. For "upgrade to the latest model" requests, the target remains `claude-opus-4-8`.

### Breaking changes (vs Opus-tier and Mythos Preview)

1. **Thinking is always on — remove all `thinking` configuration.** Adaptive thinking applies automatically whenever the `thinking` parameter is unset (an explicit `{type: "adaptive"}` is also accepted). Any other configuration is rejected: `thinking: {type: "disabled"}` and `{type: "enabled", budget_tokens: N}` both return a 400. `budget_tokens` has no replacement — the `output_config.effort` parameter is a separate output-level control, not a thinking budget.

   ```python
   # Before (Mythos Preview / older models)
   client.messages.create(
       model="claude-mythos-preview",
       max_tokens=16000,
       thinking={"type": "enabled", "budget_tokens": 10000},
       messages=[...],
   )

   # After (Claude Fable 5) — no thinking field at all
   client.messages.create(
       model="claude-fable-5",
       max_tokens=16000,
       output_config={"effort": "high"},
       messages=[...],
   )
   ```

2. **Assistant prefill is not supported.** Replace last-assistant-turn prefills with structured outputs (`output_config.format`) or system prompt instructions — same replacement patterns as the 4.6-family prefill removal above. (One exception: the fallback-credit prefill claim — the server accepts the echoed assistant message when redeeming a credit; see the refusal section below.)

3. **Interleaved scratchpad is not supported** (Mythos Preview migrators only). Inter-tool reasoning is returned in thinking blocks instead, which adaptive thinking produces automatically between tool calls.

### Protected thinking — always encrypted, model-specific

Claude Fable 5's `protected_thinking` policy protects the **raw chain of thought** — it is never exposed in responses. What you receive are **regular `thinking` blocks**, not encrypted blobs or `redacted_thinking`: `display: "summarized"` returns a readable summary of the reasoning, and with `"omitted"` — the default, same as Opus 4.8/4.7 — responses still include `thinking` blocks but the `thinking` field is an empty string. `display` controls visibility only; thinking happens and is billed the same under every setting. What's stricter on Claude Fable 5 is **replay**: pass thinking blocks back to the API **unchanged** when continuing a conversation on the same model (the standard multi-turn pattern; dropping or editing them breaks the turn).

When continuing on the same model, pass each thinking block back **exactly as received — including blocks whose `thinking` text is empty**. The API rejects blocks whose content has been *modified*, not blocks you have read; displaying the summary is fine, editing or reconstructing blocks is not.

Thinking blocks are tied to the model that produced them, but cross-model replay is forgiving: other models **silently ignore** them rather than rejecting the request (early-access builds returned `invalid_request_error`; that was reverted before launch). Ignored blocks still bill input tokens, though — so when switching models for good, e.g. after a classifier refusal, strip `thinking`/`redacted_thinking` blocks from prior assistant turns to avoid paying for dead weight. Two exceptions: fallback-credit retries must echo the refused body **unchanged**, and `fallback` blocks from a mid-output fallback stay where they appeared.

Related: a request that tries to elicit the model's internal reasoning *in the response text* can be refused with `stop_details.category: "reasoning_extraction"` — applications needing reasoning visibility should read the summarized `thinking` blocks instead of prompting for reasoning.

### New tokenizer — re-baseline tokens and cost

Claude Fable 5 uses a new tokenizer. The same content tokenizes to **roughly 30% more tokens** than on Opus-tier and older models (varies by content and workload shape). Billing is per token, so an unchanged workload can cost more after migration even before the per-token price difference.

- Coming **from `claude-mythos-preview`**: token counts are roughly unchanged (same tokenizer family).
- Coming **from Opus/Sonnet/Haiku**: do not reuse token counts, context-window budgets, or `max_tokens` settings measured on the old model.

The token counting endpoint returns counts under **both** tokenizers when you pass `model: "claude-fable-5"` — `input_tokens` (new tokenizer, what you're billed) plus `input_tokens_prior_tokenizer` (the same request under the prior-generation tokenizer) — so you can measure the delta on your own prompts before switching.

### `refusal` stop reason — handle before reading content

Claude Fable 5 runs safety classifiers on incoming requests, targeting research biology and most cybersecurity content (Claude Fable 5 is not intended for those domains); benign adjacent work — security tooling, life-sciences tasks — can occasionally trigger false positives, which is why the fallback patterns below matter even for legitimate workloads. (Most Claude consumer surfaces ship with built-in Opus 4.8 fallbacks; API callers configure their own.) A declined request returns a **successful HTTP 200** with `stop_reason: "refusal"`, plus a `stop_details` object with the policy category (`"cyber"`, `"bio"`, `"reasoning_extraction"`, or `null` — treat `null` as a permanent valid state). **Branch on `stop_reason`, never on `stop_details`** — `stop_details` is informational and can be `null` even on a refusal, and `explanation` is not guaranteed present. Note that classifier blocks and ordinary model refusals (the model itself declining) both surface as `stop_reason: "refusal"`; `stop_details.category` tells you which class you're handling, and therefore whether retrying on a fallback model is the right response. The classifier can fire **before any output** (empty `content` array; not billed at all — no input or output tokens, no rate-limit consumption) or **mid-stream** after partial output (already-streamed output is billed at normal rates — discard the partial output rather than treating it as complete). Code that reads `response.content[0]` unconditionally will break — check `stop_reason` first:

```python
response = client.messages.create(model="claude-fable-5", max_tokens=1024, messages=[...])
if response.stop_reason == "refusal":
    # classifiers declined; content is empty (pre-output) or partial (mid-stream)
    handle_refusal()
else:
    print(response.content[0].text)
```

Three ways to retry a refused request on another model, in order of preference:

**1. Server-side `fallbacks` parameter (beta: Claude API and Claude Platform on AWS) — preferred.** One round trip, a plain client, no client-side logic. Name substitute models (the only supported fallback target at launch is `claude-opus-4-8`, expansion expected); on a policy decline the API runs the next model on the same request and returns its answer, with credit-style repricing applied automatically. A `stop_reason: "refusal"` on the final response means the whole chain refused.

```python
response = client.beta.messages.create(
    model="claude-fable-5",
    max_tokens=1024,
    betas=["server-side-fallback-2026-06-01"],
    fallbacks=[{"model": "claude-opus-4-8"}],
    messages=[{"role": "user", "content": "Hello, Claude"}],
)

# Switch points: one fallback block per model that ran and declined this turn
for block in response.content:
    if block.type == "fallback":
        print(f"{block.from_.model} declined; {block.to.model} continued")

# Served-by signal: covers every fallback-served turn, INCLUDING sticky turns
# (sticky-served turns carry no fallback block — nothing declined this turn)
iterations = getattr(response.usage, "iterations", None) or []
if any(entry.type == "fallback_message" for entry in iterations):
    print(f"Served by {response.model}")
```

Key semantics:

- **Header must be exactly `server-side-fallback-2026-06-01`** — other `server-side-fallback-*` values reject the `fallbacks` param with a 400. The current header carries the *earliest* date of the series (`-2026-06-09` and `-2026-06-02` were earlier previews) — do not "correct" it to a newer-looking date. Rejected on the Batches API; not available on Bedrock/Vertex (use pattern 2 there — the SDK middleware). Entries may override `max_tokens` per hop (bounding that attempt's own output independently of the top-level `max_tokens`); `thinking`, `output_config`, and `speed` overrides are rolling out (`speed` additionally requires its beta) — until your requests accept them, include only `model` and `max_tokens` in each entry. Entries must be distinct and must be in the requested model's `allowed_fallback_models` (visible on `/v1/models` under the beta). The request *with an entry's overrides merged in* must be valid as a direct request to that entry's model.
- **Triggers on policy declines only** — rate limits, overloads, and server errors on the requested model are returned as-is, never falling back.
- **Reading the response:** a `fallback` content block (`{"type": "fallback", "from": {"model": ...}, "to": {"model": ...}}`) marks each switch point in `content`; the served-by signal is a `fallback_message` entry in `usage.iterations` (don't rely on the block — sticky-served turns have none). Top-level `model` names the model that produced the message.
- **Billing:** `usage.iterations` is the per-attempt source of truth; top-level `usage` covers only the attempt that produced the returned message. Declined-before-output attempts are reported but not billed; fallback attempts bill at the fallback model's rates. Each attempt claims the rate limits of the model that ran it — if the fallback model is rate-limited or overloaded, the refusal is returned instead with `stop_details.recommended_model` naming the canonical model ID to retry directly (populated only when the request included `fallbacks` and the attempt couldn't be made) — size fallback-model limits for expected refusal volume.
- **Sticky routing:** once a conversation falls back, later non-streaming requests with `fallbacks` are served directly by the fallback model for ~1 hour (best-effort; org-scoped content-hash record, not message content; not recorded for ZDR orgs). Handle the requested model being tried again at any time.
- **Echoing fallback turns back:** after a mid-output fallback, omit `thinking`, `redacted_thinking`, and `tool_use` blocks — plus any `server_tool_use` block without its matching `server_tool_result`, and any other unrecognized model-internal block type — that appear *before* the final `fallback` block; text blocks, paired server-tool blocks, and everything after the boundary echo normally. The `fallback` block itself is an ignored audit marker (keep or drop). Streaming: the retry happens on the same stream and already-received content is never invalidated — a pre-output block is seamless (`message_start` names the fallback model; the `fallback` block arrives as an ordinary `content_block_start`, first in `content` — there is no special SSE event type; note `message_start` arrives only after the declined attempt, so time-to-first-byte includes it), and a mid-stream block keeps the partial, marks the boundary with the block, and continues — only the partial's `text` blocks are passed to the fallback model as continuation context (other block types stay in `content` but aren't part of it). Sticky routing is **not consulted on streaming requests** in the initial release, so on streams the `fallback` block check is the complete signal; non-streaming mid-output declines omit the declined partial entirely.

**2. SDK client-side middleware — for providers without server-side fallbacks (Bedrock, Vertex).** Register it on the client and every `client.beta.messages` request (streaming included) retries refusals automatically, splicing the fallback model's events onto the open stream in the same wire shape as pattern 1 (a `fallback` content block at each boundary, per-hop `usage.iterations`). It is also a beta surface: the middleware sends the `fallback-credit-2026-06-01` header by default so retries are repriced via credit tokens (override with its `betas` option). `BetaFallbackState` pins follow-up turns to the model that accepted (the client-side analog of sticky routing) — reuse one state object per conversation:

```python
from anthropic import Anthropic, BetaFallbackState, BetaRefusalFallbackMiddleware

client = Anthropic(middleware=[BetaRefusalFallbackMiddleware([{"model": "claude-opus-4-8"}])])
state = BetaFallbackState()  # pins follow-ups to the model that accepted
with state:
    response = client.beta.messages.create(model="claude-fable-5", max_tokens=1024, messages=messages)
```

Create **one state per conversation** — it is the pinning scope; sharing one across conversations pins unrelated threads together, and a conversation without a state is never pinned. Per-language naming (from the GA SDK examples — don't improvise):

- **TypeScript**: `betaRefusalFallbackMiddleware([...])` in the client's `middleware` array; pass `{ fallbackState: state }` (a `BetaFallbackState`) as a request option.
- **Go**: `option.WithMiddleware(betafallback.BetaRefusalFallbackMiddleware([]anthropic.BetaFallbackParam{{Model: ...}}))` (package `lib/betafallback`); state via `betafallback.WithBetaFallbackState(&betafallback.BetaFallbackState{})` passed as a request option. Server-side equivalents: `Fallbacks: []anthropic.BetaFallbackParam{...}` + `anthropic.AnthropicBetaServerSideFallback2026_06_01`.
- **C#**: it's a *handler* — `new AnthropicClient { Handlers = [new BetaRefusalFallbackHandler { Fallbacks = [new(Model.ClaudeOpus4_8)] }] }` (namespace `Anthropic.Helpers`); state via `BetaFallbackState.Create()` scoped per call with `using (fallbackState.Use()) { ... }`. Server-side equivalents: `Fallbacks = [new(Model.ClaudeOpus4_8)]` + `AnthropicBeta.ServerSideFallback2026_06_01`.

For languages not listed (Java, Ruby, PHP) — or for a full runnable program in any language — each public SDK repo ships a fallbacks example under `examples/` (e.g. `examples/fallbacks.py`, `examples/refusal-fallback/`): WebFetch the repo from `shared/live-sources.md` § SDK Repositories rather than improvising the binding.

**3. Hand-rolled retry + fallback credit (raw HTTP, or SDKs without the middleware).** Detect the refusal via `stop_reason` and re-send the conversation as-is on a model with broader availability such as `claude-opus-4-8` (Claude Fable 5's protected thinking blocks are silently ignored by other models — no stripping required); keep using the fallback model for subsequent turns. **Fallback credit** (beta: Claude API, Bedrock, Vertex) makes those retries cheaper. Prompt caches are per-model, so a plain retry pays cold cache-writes on the new model. With the `fallback-credit-2026-06-01` beta header (send it on both the original request and the retry), a refusal's `stop_details` carries `fallback_credit_token` (opaque; `null` when unavailable) and `fallback_has_prefill_claim`. Echo the token as the top-level `fallback_credit_token` request parameter on the retry (typed in the GA SDKs; on a pre-GA SDK pass it via `extra_body`) and the previously-cached span bills at cache-read rates — the retry costs what it would have if the conversation had been on that model all along. Rules: the retry body must match the refused request **exactly** in every prompt-shaping field (`system`, `messages`, `tools`, `tool_choice`, `thinking` — do **not** strip thinking blocks when redeeming a credit — the server handles them); the retry model must be in the refused model's `allowed_fallback_models`; the token expires in 5 minutes; Batches results carry no tokens. If `fallback_has_prefill_claim` is `true`, append one assistant message echoing the refused response's `content` — the retry model continues from where the refused model stopped (and completed server-tool work isn't re-run). When echoing, strip trailing whitespace from a final `text` block (the prefill validator rejects it; the credit match tolerates that edit), after omitting any unpaired `tool_use` blocks. On a 400, fall back to the unchanged body with the token; on a 400 naming `fallback_credit_token`, retry without it (credit forfeited).

**Migrating code built on the v1 preview.** If the code you're editing carries any of these markers, it targets the discontinued early-access surface — migrate it to the v2 shapes above, and ship the header and parameter changes together (the v1 parameter shape under the v2 header is a 400):

| v1 marker (replace) | v2 |
|---|---|
| `server-side-fallback-2026-06-09` / `-2026-06-02` header | `server-side-fallback-2026-06-01` |
| `fallback: {model, on_partial}` single object | `fallbacks: [{model, ...}]` array (1–3); `on_partial` no longer exists — partial-output behavior is fixed (streams keep the partial; non-streaming omits it). Unknown keys in an entry are a 400 |
| Top-level `response.fallback` object (`from_model`, `reason`) | Never emitted — read `fallback` content blocks (switch points, no `reason` field) and `usage.iterations` (served-by) |
| `event: fallback` SSE with discard indices | No dedicated event; streamed content is never invalidated — the switch arrives as an ordinary `content_block_start`/`stop` pair of type `fallback` |
| `fallback_primary` / `fallback_retry` iteration types | Blocked attempts are plain `message` entries; the serving attempt is `fallback_message` |
| `reason: "sticky"` | No reason field — sticky turns carry no block; detect via `fallback_message` in `usage.iterations` + `response.model` |
| `recommended_model` meaning "primary served the refusal" | Now populated only when the fallback attempt *couldn't run* (rate-limited/overloaded) — its presence means a direct retry on that model may succeed, not that it refused too |

### Data retention requirement

Claude Fable 5 requires **30-day data retention** and is not available under zero data retention. Requests from an organization whose data-retention configuration doesn't meet the requirement return `400 invalid_request_error` — if a migration suddenly 400s with no obvious request problem, check the org's retention configuration before debugging the payload. On Amazon Bedrock, Google Vertex AI, and Microsoft Foundry, data-retention requirements are set by each platform.

### What carries over unchanged

Same Messages API and tool-use patterns as Opus-tier and Mythos Preview. Supported at launch: `output_config.effort` (`low`/`medium`/`high`/`xhigh`/`max`), Task Budgets (beta, `task-budgets-2026-03-13` header), compaction (beta, `compact-2026-01-12` header), the memory tool, tool-call clearing via context editing, and high-resolution vision (no downscaling cap, as on Opus 4.7+).

### Behavioral shifts (prompt-tunable)

None of these are API-breaking, but they're where migrated workloads feel different. Claude Fable 5's biggest gains are on work *above* what prior models could do (long-horizon autonomous runs, first-shot implementations of well-specified systems, end-to-end enterprise deliverables — financial analysis, spreadsheets, slides, docs — code review/debugging and repository-history search, vision on dense or degraded images — it's explicitly trained to use bash and crop tools on flipped/blurry/noisy inputs — navigating ambiguity, parallel sub-agent delegation and collaboration — it reliably sustains ongoing communications with long-running sub-agents and peer agents; note bug-finding gains exclude security-focused analysis, where the cyber classifiers apply) — don't evaluate it only on workloads older models already handled.

**Longer turns by default — the biggest structural shift.** Individual requests on hard tasks can run many minutes at higher effort (a 15-minute single request is normal when the task involves gathering context, building, and self-verifying). Before migrating, plan timeouts, streaming, and user-facing progress indicators; structure work so callers check in on runs asynchronously rather than blocking inside one request. On ambiguous tasks Claude Fable 5 may need a small nudge to avoid overplanning:

> When you have enough information to act, act. Do not re-derive facts already established in the conversation, re-litigate a decision the user has already made, or narrate options you will not pursue in user-facing messages. If you are weighing a choice, give a recommendation, not an exhaustive survey. This does not apply to thinking blocks.

**Consider all effort levels.** `output_config.effort` is the primary intelligence/latency/cost control. Recommended defaults: `high` for most tasks, `xhigh` for the most capability-sensitive workloads, `medium`/`low` for routine work. Lower effort settings — including `low` — still perform very well on Claude Fable 5, often exceeding the `xhigh` or even `max` performance of previous models. Reduce effort if a task completes correctly but takes longer than necessary, or for a quicker interactive working style. At higher effort on routine work, Claude Fable 5 can gather context and deliberate beyond what the task needs (the flip side: higher effort buys excellent verification behavior and the most rigorous outputs). To prevent unrequested tidying or refactoring at higher effort:

> Don't add features, refactor, or introduce abstractions beyond what the task requires. A bug fix doesn't need surrounding cleanup and a one-shot operation usually doesn't need a helper. Don't design for hypothetical future requirements - do the simplest thing that works well. Avoid premature abstraction. Avoid half-finished implementations either. Don't add error handling, fallbacks, or validation for scenarios that cannot happen. Trust internal code and framework guarantees. Only validate at system boundaries (user input, external APIs). Don't use feature flags or backwards-compatibility shims when you can just change the code.

**Instruction following is strong — use it.** Claude Fable 5 is very responsive to explicit communication-style sections in system prompts; invest in them rather than fighting output style downstream. Un-steered — especially at higher effort — it can elaborate beyond what the task needs: heavily-structured PR descriptions, sections on alternatives that weren't chosen, comments narrating what the next line does. You don't need to enumerate these behaviors by name; a brief instruction is just as effective:

> Lead with the outcome. Your first sentence after finishing should answer "what happened" or "what did you find" — the thing the user would ask for if they said "just give me the TLDR." Supporting detail and reasoning come after. Being readable and being concise are different things, and readability matters more. The way to keep output short is to be selective about what you include (drop details that don't change what the reader would do next), not to compress the writing into fragments, abbreviations, arrow chains like A → B → fails, or jargon.

**Ground progress claims on long runs.** Require progress claims to be audited against tool results — in testing this nearly eliminated fabricated status reports on tasks designed to elicit them:

> Before reporting progress, audit each claim against a tool result from this session. Only report work you can point to evidence for; if something is not yet verified, say so explicitly. Report outcomes faithfully: if tests fail, say so with the output; if a step was skipped, say that; when something is done and verified, state it plainly without hedging.

**State boundaries explicitly.** Claude Fable 5 sometimes takes unrequested-but-adjacent actions (e.g. composing an email straight to drafts, creating backup git branches). Define what it should *not* do:

> When the user is describing a problem, asking a question, or thinking out loud rather than requesting a change, the deliverable is your assessment. Report your findings and stop. Don't apply a fix until they ask for one. Before running a command that changes system state — restarts, deletes, config edits — check that the evidence actually supports that specific action. A signal that pattern-matches to a known failure may have a different cause.

**Let it delegate — asynchronously.** Parallel sub-agents are dependable on Claude Fable 5 — instead of suppressing delegation (a common prior-model guardrail), use sub-agents frequently and give explicit guidance on *when* delegation is desirable. Sub-agents that communicate **asynchronously** with the orchestrator outperform spawn-and-block: long-lived agents keep their context instead of re-establishing it per subtask (cache-read savings), the orchestrator isn't bottlenecked on the slowest sub-agent, and context persists across subtasks.

> Delegate independent subtasks to sub-agents and keep working while they run. Intervene if a sub-agent goes off track or is missing relevant context.

**Give it a memory surface.** Claude Fable 5 performs notably better when it can write learnings somewhere for future reference — even a plain `.md` file. Tell it where, tell it to consult that file in future sessions, and give it a format:

> Store one lesson per file with a one-line summary at the top. Record corrections and confirmed approaches alike, including why they mattered. Don't save what the repo or chat history already records; update an existing note rather than creating a duplicate; delete notes that turn out to be wrong.

**Rare: early stopping.** Deep into long sessions it can occasionally end a turn with a text-only statement of intent ("I'll now run X") without the tool call, or ask permission it doesn't need. A "continue" recovers it interactively; for autonomous pipelines add a system reminder:

> You are operating autonomously. The user is not watching in real time and cannot answer questions mid-task, so asking 'Want me to…?' or 'Shall I…?' will block the work. For reversible actions that follow from the original request, proceed without asking. Offering follow-ups after the task is done is fine; asking permission after already discussing with the user before doing the work is not. Before ending your turn, check your last paragraph. If it is a plan, an analysis, a question, a list of next steps, or a promise about work you have not done ('I'll…', 'let me know when…'), do that work now with tool calls. End your turn only when the task is complete or you are blocked on input only the user can provide.

**Rare: context anxiety.** In very long sessions it can worry about running out of context — suggesting a new session or trimming its own work — most often when the harness surfaces a remaining-token countdown. Avoid showing explicit context-budget counts; if you must:

> You have ample context remaining. Do not stop, summarize, or suggest a new session on account of context limits – continue the work.

**Give the reason, not just the request.** Claude Fable 5 performs better when it understands the intent behind a request — it connects the task to relevant information rather than inferring intent on its own. This matters most for long-running agents juggling context from disparate workstreams:

> I'm working on [the larger task] for [who it's for]. They need [what the output enables]. With that in mind: [request].

**Readability in long agentic sessions.** Deep into extended conversations (many tool calls, large working context) Claude Fable 5 can produce text users find hard to follow — dense arrow-chain shorthand, implementation-level detail, references to thinking the user never saw. A communication-style addendum strongly mitigates this; adapt:

> Terse shorthand is fine between tool calls (that's you thinking out loud, and brevity there is good). Your final summary is different: it's for a reader who didn't see any of that. If you've been working for a while without the user watching - overnight, across many tool calls, since they last spoke - your final message is their first look at any of it. Write it as a re-grounding, not a continuation of your working thread: the outcome first, then the one or two things you need from them, each explained as if new. The vocabulary you built up while working is yours, not theirs; leave it behind unless you re-introduce it. When you write the summary at the end, drop the working shorthand. Write complete sentences. Spell out terms instead of abbreviating them. Don't use arrow chains, hyphen-stacked compounds, or labels you made up earlier — the reader doesn't have the context to decode them. When you mention files, commits, flags, or other identifiers, give each one its own plain-language clause saying what it is or what changed — never pack several into one parenthesized run or slash-separated list. Open with the outcome: one sentence on what happened or what you found. Then the supporting detail. If you have to choose between short and clear, choose clear.

### Long-running agent recommendations

- **Make self-verification explicit.** For long-running builds, instruct it to establish and run its own checking harness on a cadence ("Establish a method for checking your own work as you build; run it every [interval], verifying against the specification with sub-agents"). Separate fresh-context verifier sub-agents tend to outperform self-critique.
- **De-prescribe migrated prompts and skills.** Prompts and skills written for prior models are often too prescriptive for Claude Fable 5 and *reduce* output quality. After migrating, A/B the workload with older step-by-step scaffolding removed — prefer stating the goal and constraints over enumerating the steps. Claude Fable 5 is also good at updating skills on the fly from what it learns mid-task — let it.
- **Start at the top of your difficulty range.** The teams with the best early-access outcomes gave it their hardest unsolved problems first — have it scope the problem, ask questions, then execute.
- **Add a `send_to_user` tool for verbatim mid-task delivery.** When an asynchronous agent must deliver something the user sees *exactly as written* mid-run (a deliverable, a progress update with specific numbers, a direct answer), give it a client-side tool whose input you render directly in the UI — tool inputs are never summarized, so content arrives intact. Return a simple acknowledgement as the tool result:

```json
{
  "name": "send_to_user",
  "description": "Display a message directly to the user. Use this for progress updates, partial results, or content the user must see exactly as written before the task finishes.",
  "input_schema": {
    "type": "object",
    "properties": {
      "message": { "type": "string", "description": "The content to display to the user." }
    },
    "required": ["message"]
  }
}
```

For agents that only narrate routine progress, default summaries are typically adequate without this tool.

### Claude Fable 5 Migration Checklist

- [ ] **[BLOCKS]** Update the `model=` string to `claude-fable-5` (`claude-mythos-5` for Mythos Preview migrators in Project Glasswing)
- [ ] **[BLOCKS]** Remove `thinking: {type: "disabled"}` (errors on Claude Fable 5)
- [ ] **[BLOCKS]** Replace assistant prefill with structured outputs or system prompt instructions
- [ ] **[BLOCKS]** Confirm the org meets the 30-day data-retention requirement (ZDR orgs get `400 invalid_request_error` on every request)
- [ ] **[BLOCKS]** Remove all other `thinking` configuration (`{type: "enabled", budget_tokens: N}` returns a 400, same as on Opus 4.7/4.8); control depth with `output_config.effort` instead
- [ ] **[TUNE]** Re-baseline token counts, context budgets, `max_tokens`, and cost — ~30% more tokens vs Opus-tier (roughly unchanged from Mythos Preview); use `count_tokens` with `model: "claude-fable-5"` to measure
- [ ] **[TUNE]** Add `stop_reason == "refusal"` handling before reading `response.content` (pre-output: empty + unbilled; mid-stream: partial output billed — discard); pick a retry strategy — client-side (replay history as-is; other models ignore Fable's thinking blocks), fallback credit (`fallback-credit-2026-06-01`, exact body), or server-side `fallbacks` (`server-side-fallback-2026-06-01`, Claude API and Claude Platform on AWS)
- [ ] **[TUNE]** If you surfaced thinking text to users, plan for protected (encrypted) thinking — pass blocks back unchanged on the same model, never render or cross-model them
- [ ] **[TUNE]** Plan for minutes-long turns: timeouts, streaming, async check-ins, progress UX (see Behavior changes above)
- [ ] **[TUNE]** Run an effort sweep including low/medium for routine workloads; add the no-tidying instruction if higher effort produces unrequested refactors
- [ ] **[TUNE]** A/B with prior-model scaffolding removed — over-prescriptive prompts/skills reduce Claude Fable 5 output quality

---

## Verify the Migration

After updating, spot-check that the new model is actually being used. Replace `YOUR_TARGET_MODEL` with the model string you migrated to (e.g. `claude-fable-5`, `claude-opus-4-8`, `claude-opus-4-7`, `claude-sonnet-4-6`, `claude-haiku-4-5`) and keep the assertion prefix in sync:

```python
YOUR_TARGET_MODEL = "claude-opus-4-8"  # or "claude-opus-4-7", "claude-sonnet-4-6", "claude-haiku-4-5"
response = client.messages.create(model=YOUR_TARGET_MODEL, max_tokens=64, messages=[...])
assert response.model.startswith(YOUR_TARGET_MODEL), response.model
```

For rate-limit headroom changes, pricing, or capability deltas (vision, structured outputs, effort support), query the Models API:

```python
m = client.models.retrieve(YOUR_TARGET_MODEL)
m.max_input_tokens, m.max_tokens
m.capabilities["effort"]["max"]["supported"]
```

See `shared/models.md` for the full capability lookup pattern.

FILE:shared/models.md
# Claude Model Catalog

**Only use exact model IDs listed in this file.** Never guess or construct model IDs — incorrect IDs will cause API errors. Use aliases wherever available. For the latest information, WebFetch the Models Overview URL in `shared/live-sources.md`, or query the Models API directly (see Programmatic Model Discovery below).

## Programmatic Model Discovery

For **live** capability data — context window, max output tokens, feature support (thinking, vision, effort, structured outputs, etc.) — query the Models API instead of relying on the cached tables below. Use this when the user asks "what's the context window for X", "does model X support vision/thinking/effort", "which models support feature Y", or wants to select a model by capability at runtime.

```python
m = client.models.retrieve("claude-opus-4-8")
m.id                 # "claude-opus-4-8"
m.display_name       # "Claude Opus 4.8"
m.max_input_tokens   # context window (int)
m.max_tokens         # max output tokens (int)

# capabilities is an untyped nested dict — bracket access, check ["supported"] at the leaf
caps = m.capabilities
caps["image_input"]["supported"]                       # vision
caps["thinking"]["types"]["adaptive"]["supported"]     # adaptive thinking
caps["effort"]["max"]["supported"]                     # effort: max (also low/medium/high)
caps["structured_outputs"]["supported"]
caps["context_management"]["compact_20260112"]["supported"]

# filter across all models — iterate the page object directly (auto-paginates); do NOT use .data
[m for m in client.models.list()
 if m.capabilities["thinking"]["types"]["adaptive"]["supported"]
 and m.max_input_tokens >= 200_000]
```

Top-level fields (`id`, `display_name`, `max_input_tokens`, `max_tokens`) are typed attributes. `capabilities` is a dict — use bracket access, not attribute access. The API returns the full capability tree for every model with `supported: true/false` at each leaf, so bracket chains are safe without `.get()` guards. TypeScript SDK: same method names, also auto-paginates on iteration.

### Raw HTTP

```bash
curl https://api.anthropic.com/v1/models/claude-opus-4-8 \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01"
```

```json
{
  "id": "claude-opus-4-8",
  "display_name": "Claude Opus 4.8",
  "max_input_tokens": 1000000,
  "max_tokens": 128000,
  "capabilities": {
    "image_input": {"supported": true},
    "structured_outputs": {"supported": true},
    "thinking": {"supported": true, "types": {"enabled": {"supported": false}, "adaptive": {"supported": true}}},
    "effort": {"supported": true, "low": {"supported": true}, …, "max": {"supported": true}},
    …
  }
}
```

## Current Models (recommended)

| Friendly Name     | Alias (use this)    | Full ID                       | Context        | Max Output | Status |
|-------------------|---------------------|-------------------------------|----------------|------------|--------|
| Claude Fable 5    | `claude-fable-5`      | —                             | 1M             | 128K       | Active |
| Claude Mythos 5   | `claude-mythos-5`     | —                             | 1M             | 128K       | Active (Project Glasswing only) |
| Claude Opus 4.8   | `claude-opus-4-8`   | —                             | 1M             | 128K       | Active |
| Claude Opus 4.7   | `claude-opus-4-7`   | —                             | 1M             | 128K       | Active |
| Claude Opus 4.6   | `claude-opus-4-6`   | —                             | 1M             | 128K       | Active |
| Claude Sonnet 4.6 | `claude-sonnet-4-6` | -                             | 1M             | 64K        | Active |
| Claude Haiku 4.5  | `claude-haiku-4-5`  | `claude-haiku-4-5-20251001`   | 200K           | 64K        | Active |

### Model Descriptions
- **Claude Fable 5** — Anthropic's most capable widely released model, for the most demanding reasoning and long-horizon agentic work. Same API surface as Opus 4.7/4.8 with one new breaking change: an explicit `thinking: {type: "disabled"}` returns a 400 — omit the `thinking` parameter instead (thinking is always on, returned in protected/encrypted form). New tokenizer (~30% more tokens than Opus-tier for the same content). Safety classifiers may return `stop_reason: "refusal"`. No assistant prefill. Requires 30-day data retention (not available under ZDR). $10/$50 per MTok; 1M context window (default), 128K max output. See `shared/model-migration.md` → Migrating to Claude Fable 5.
- **Claude Mythos 5** — Same capabilities, pricing, limits, and API behavior as Claude Fable 5; only the model ID differs. Available exclusively through Project Glasswing, where it joins (and succeeds) the invitation-only Claude Mythos Preview (`claude-mythos-preview`). Use it only when the org participates in Project Glasswing; otherwise use claude-fable-5.
- **Claude Opus 4.8** — The most capable Opus-tier model — highly autonomous, state-of-the-art on long-horizon agentic work, knowledge work, and memory; clearer, warmer writing. Same API surface as Opus 4.7 (adaptive thinking only; sampling parameters and `budget_tokens` removed). 1M context window at standard API pricing (no long-context premium). See `shared/model-migration.md` → Migrating to Opus 4.8 — a 4.7 → 4.8 move is a model-ID swap plus prompt re-tuning, no new breaking changes.
- **Claude Opus 4.7** — Previous-generation Opus. Highly autonomous; strong on long-horizon agentic work, knowledge work, vision, and memory. Adaptive thinking only; sampling parameters and `budget_tokens` removed. 1M context window. See `shared/model-migration.md` → Migrating to Opus 4.7.
- **Claude Opus 4.6** — Older Opus. Supports adaptive thinking (recommended), 128K max output tokens (requires streaming for large outputs). 1M context window.
- **Claude Sonnet 4.6** — Our best combination of speed and intelligence. Supports adaptive thinking (recommended). 1M context window. 64K max output tokens.
- **Claude Haiku 4.5** — Fastest and most cost-effective model for simple tasks.

## Legacy Models (still active)

| Friendly Name     | Alias (use this)    | Full ID                       | Status |
|-------------------|---------------------|-------------------------------|--------|
| Claude Opus 4.5   | `claude-opus-4-5`   | `claude-opus-4-5-20251101`    | Active |
| Claude Opus 4.1   | `claude-opus-4-1`   | `claude-opus-4-1-20250805`    | Deprecated (retires 2026-08-05 — migrate to `claude-opus-4-8`) |
| Claude Sonnet 4.5 | `claude-sonnet-4-5` | `claude-sonnet-4-5-20250929`  | Active |

## Deprecated Models (retiring soon)

| Friendly Name     | Alias (use this)    | Full ID                       | Status     | Retires      |
|-------------------|---------------------|-------------------------------|------------|--------------|
| Claude Sonnet 4   | `claude-sonnet-4-0` | `claude-sonnet-4-20250514`    | Deprecated | TBD          |
| Claude Opus 4     | `claude-opus-4-0`   | `claude-opus-4-20250514`      | Deprecated | TBD          |
| Claude Haiku 3    | —                   | `claude-3-haiku-20240307`     | Deprecated | Apr 19, 2026 |

## Retired Models (no longer available)

| Friendly Name     | Full ID                       | Retired     |
|-------------------|-------------------------------|-------------|
| Claude Sonnet 3.7 | `claude-3-7-sonnet-20250219`  | Feb 19, 2026 |
| Claude Haiku 3.5  | `claude-3-5-haiku-20241022`   | Feb 19, 2026 |
| Claude Opus 3     | `claude-3-opus-20240229`      | Jan 5, 2026 |
| Claude Sonnet 3.5 | `claude-3-5-sonnet-20241022`  | Oct 28, 2025 |
| Claude Sonnet 3.5 | `claude-3-5-sonnet-20240620`  | Oct 28, 2025 |
| Claude Sonnet 3   | `claude-3-sonnet-20240229`    | Jul 21, 2025 |
| Claude 2.1        | `claude-2.1`                  | Jul 21, 2025 |
| Claude 2.0        | `claude-2.0`                  | Jul 21, 2025 |

## Resolving User Requests

When a user asks for a model by name, use this table to find the correct model ID:

| User says...                              | Use this model ID              |
|-------------------------------------------|--------------------------------|
| "fable", "most capable model"             | `claude-fable-5`                 |
| "most powerful"                           | `claude-fable-5`                 |
| "mythos", "mythos 5"                      | `claude-mythos-5` (Project Glasswing participants only; otherwise use `claude-fable-5`) |
| "mythos preview"                          | `claude-mythos-5` (successor to `claude-mythos-preview` — see migration guide) |
| "opus"                                    | `claude-opus-4-8`              |
| "opus 4.8"                                | `claude-opus-4-8`              |
| "opus 4.7"                                | `claude-opus-4-7`              |
| "opus 4.6"                                | `claude-opus-4-6`              |
| "opus 4.5"                                | `claude-opus-4-5`              |
| "opus 4.1"                                | `claude-opus-4-1` (deprecated, retires 2026-08-05 — suggest `claude-opus-4-8`) |
| "opus 4", "opus 4.0"                      | `claude-opus-4-0` (deprecated — suggest `claude-opus-4-8`) |
| "sonnet", "balanced"                      | `claude-sonnet-4-6`            |
| "sonnet 4.6"                              | `claude-sonnet-4-6`            |
| "sonnet 4.5"                              | `claude-sonnet-4-5`            |
| "sonnet 4", "sonnet 4.0"                  | `claude-sonnet-4-0` (deprecated — suggest `claude-sonnet-4-6`) |
| "sonnet 3.7"                              | Retired — suggest `claude-sonnet-4-6` |
| "sonnet 3.5"                              | Retired — suggest `claude-sonnet-4-6` |
| "haiku", "fast", "cheap"                  | `claude-haiku-4-5`             |
| "haiku 4.5"                               | `claude-haiku-4-5`             |
| "haiku 3.5"                               | Retired — suggest `claude-haiku-4-5` |
| "haiku 3"                                 | Deprecated — suggest `claude-haiku-4-5` |

FILE:shared/prompt-caching.md
# Prompt Caching — Design & Optimization

This file covers how to design prompt-building code for effective caching. For language-specific syntax, see the `## Prompt Caching` section in each language's README or single-file doc.

## The one invariant everything follows from

**Prompt caching is a prefix match. Any change anywhere in the prefix invalidates everything after it.**

The cache key is derived from the exact bytes of the rendered prompt up to each `cache_control` breakpoint. A single byte difference at position N — a timestamp, a reordered JSON key, a different tool in the list — invalidates the cache for all breakpoints at positions ≥ N.

Render order is: `tools` → `system` → `messages`. A breakpoint on the last system block caches both tools and system together.

Design the prompt-building path around this constraint. Get the ordering right and most caching works for free. Get it wrong and no amount of `cache_control` markers will help.

---

## Workflow for optimizing existing code

When asked to add or optimize caching:

1. **Trace the prompt assembly path.** Find where `system`, `tools`, and `messages` are constructed. Identify every input that flows into them.
2. **Classify each input by stability:**
   - Never changes → belongs early in the prompt, before any breakpoint
   - Changes per-session → belongs after the global prefix, cache per-session
   - Changes per-turn → belongs at the end, after the last breakpoint
   - Changes per-request (timestamps, UUIDs, random IDs) → **eliminate or move to the very end**
3. **Check rendered order matches stability order.** Stable content must physically precede volatile content. If a timestamp is interpolated into the system prompt header, everything after it is uncacheable regardless of markers.
4. **Place breakpoints at stability boundaries.** See placement patterns below.
5. **Audit for silent invalidators.** See anti-patterns table.

---

## Placement patterns

### Large system prompt shared across many requests

Put a breakpoint on the last system text block. If there are tools, they render before system — the marker on the last system block caches tools + system together.

```json
"system": [
  {"type": "text", "text": "<large shared prompt>", "cache_control": {"type": "ephemeral"}}
]
```

### Multi-turn conversations

Put a breakpoint on the last content block of the most-recently-appended turn. Each subsequent request reuses the entire prior conversation prefix. Earlier breakpoints remain valid read points, so hits accrue incrementally as the conversation grows.

```json
// Last content block of the last user turn
messages[-1].content[-1].cache_control = {"type": "ephemeral"}
```

### Shared prefix, varying suffix

Many requests share a large fixed preamble (few-shot examples, retrieved docs, instructions) but differ in the final question. Put the breakpoint at the end of the **shared** portion, not at the end of the whole prompt — otherwise every request writes a distinct cache entry and nothing is ever read.

```json
"messages": [{"role": "user", "content": [
  {"type": "text", "text": "<shared context>", "cache_control": {"type": "ephemeral"}},
  {"type": "text", "text": "<varying question>"}  // no marker — differs every time
]}]
```

### Mid-conversation system messages

**Beta, model-gated.** When an operator instruction arrives mid-conversation — a mode switch, updated context, dynamically injected state — send it as `{"role": "system", "content": "..."}` appended to `messages[]`, rather than editing top-level `system`. Editing top-level `system` changes the prefix ahead of the entire conversation history, so every cached turn is re-processed uncached; a `role: "system"` message sits after the history and leaves the cached prefix intact.

```json
// Top-level system stays byte-identical; new instruction goes after the cached history
"system": [{"type": "text", "text": "<stable core>", "cache_control": {"type": "ephemeral"}}],
"messages": [
  ...history,
  {"role": "user", "content": "..."},
  {"role": "system", "content": "Terse mode enabled — keep responses under 40 words."}
]
```

This is also the prompt-injection-safe replacement for embedding operator instructions as text inside a user turn (the `<system-reminder>` pattern): both have the same caching profile, but `role: "system"` is the non-spoofable operator channel, whereas text inside user/tool content can be forged by anything that writes to user-visible input.

Requires `anthropic-beta: mid-conversation-system-2026-04-07`. Must follow a `role: "user"` message (or an assistant message ending in a server tool result); cannot be `messages[0]` — use top-level `system` for the initial prompt. Content is text-only. Model-gated — unsupported models return a 400 (`BadRequestError`: `role 'system' is not supported on this model`); catch that error and fall back to putting the instruction in a user-turn `<system-reminder>` block.

### Prompts that change from the beginning every time

Don't cache. If the first 1K tokens differ per request, there is no reusable prefix. Adding `cache_control` only pays the cache-write premium with zero reads. Leave it off.

---

## Architectural guidance

These are the decisions that matter more than marker placement. Fix these first.

**Keep the system prompt frozen.** Don't interpolate "current date: X", "mode: Y", "user name: Z" into the system prompt — those sit at the front of the prefix and invalidate everything downstream. Inject dynamic context later in `messages` instead — as a `{"role": "system", ...}` message where supported (see § Mid-conversation system messages above), or as text in a user message otherwise. A message at turn 5 invalidates nothing before turn 5.

**Don't change tools or model mid-conversation.** Tools render at position 0; adding, removing, or reordering a tool invalidates the entire cache. Same for switching models (caches are model-scoped). If you need "modes", don't swap the tool set — give Claude a tool that records the mode transition, or pass the mode as message content. Serialize tools deterministically (sort by name).

**Fork operations must reuse the parent's exact prefix.** Side computations (summarization, compaction, sub-agents) often spin up a separate API call. If the fork rebuilds `system` / `tools` / `model` with any difference, it misses the parent's cache entirely. Copy the parent's `system`, `tools`, and `model` verbatim, then append fork-specific content at the end.

---

## Silent invalidators

When reviewing code, grep for these inside anything that feeds the prompt prefix:

| Pattern | Why it breaks caching |
|---|---|
| `datetime.now()` / `Date.now()` / `time.time()` in system prompt | Prefix changes every request |
| `uuid4()` / `crypto.randomUUID()` / request IDs early in content | Same — every request is unique |
| `json.dumps(d)` without `sort_keys=True` / iterating a `set` | Non-deterministic serialization → prefix bytes differ |
| f-string interpolating session/user ID into system prompt | Per-user prefix; no cross-user sharing |
| Conditional system sections (`if flag: system += ...`) | Every flag combination is a distinct prefix |
| `tools=build_tools(user)` where set varies per user | Tools render at position 0; nothing caches across users |

Fix by moving the dynamic piece after the last breakpoint, making it deterministic, or deleting it if it's not load-bearing.

---

## API reference

```json
"cache_control": {"type": "ephemeral"}              // 5-minute TTL (default)
"cache_control": {"type": "ephemeral", "ttl": "1h"} // 1-hour TTL
```

- Max **4** `cache_control` breakpoints per request.
- Goes on any content block: system text blocks, tool definitions, message content blocks (`text`, `image`, `tool_use`, `tool_result`, `document`).
- Top-level `cache_control` on `messages.create()` auto-places on the last cacheable block — simplest option when you don't need fine-grained placement.
- Minimum cacheable prefix is model-dependent. Shorter prefixes silently won't cache even with a marker — no error, just `cache_creation_input_tokens: 0`:

| Model | Minimum |
|---|---:|
| Opus 4.8, Opus 4.7, Opus 4.6, Opus 4.5, Haiku 4.5 | 4096 tokens |
| Fable 5, Sonnet 4.6, Haiku 3.5, Haiku 3 | 2048 tokens |
| Sonnet 4.5, Sonnet 4.1, Sonnet 4, Sonnet 3.7 | 1024 tokens |

A 3K-token prompt caches on Sonnet 4.5 and Fable 5 but silently won't on Opus 4.8.

**Economics:** Cache reads cost ~0.1× base input price. Cache writes cost **1.25× for 5-minute TTL, 2× for 1-hour TTL**. Break-even depends on TTL: with 5-minute TTL, two requests break even (1.25× + 0.1× = 1.35× vs 2× uncached); with 1-hour TTL, you need at least three requests (2× + 0.2× = 2.2× vs 3× uncached). The 1-hour TTL keeps entries alive across gaps in bursty traffic, but the doubled write cost means it needs more reads to pay off.

---

## Verifying cache hits

The response `usage` object reports cache activity:

| Field | Meaning |
|---|---|
| `cache_creation_input_tokens` | Tokens written to cache this request (you paid the ~1.25× write premium) |
| `cache_read_input_tokens` | Tokens served from cache this request (you paid ~0.1×) |
| `input_tokens` | Tokens processed at full price (not cached) |

If `cache_read_input_tokens` is zero across repeated requests with identical prefixes, a silent invalidator is at work — diff the rendered prompt bytes between two requests to find it.

**`input_tokens` is the uncached remainder only.** Total prompt size = `input_tokens + cache_creation_input_tokens + cache_read_input_tokens`. If your agent ran for hours but `input_tokens` shows 4K, the rest was served from cache — check the sum, not the single field.

Language-specific access: `response.usage.cache_read_input_tokens` (Python/TS/Ruby), `$message->usage->cacheReadInputTokens` (PHP), `resp.Usage.CacheReadInputTokens` (Go/C#), `.usage().cacheReadInputTokens()` (Java).

---

## Invalidation hierarchy

Not every parameter change invalidates everything. The API has three cache tiers, and changes only invalidate their own tier and below:

| Change | Tools cache | System cache | Messages cache |
|---|:---:|:---:|:---:|
| Tool definitions (add/remove/reorder) | ❌ | ❌ | ❌ |
| Model switch | ❌ | ❌ | ❌ |
| `speed`, web-search, citations toggle | ✅ | ❌ | ❌ |
| System prompt content | ✅ | ❌ | ❌ |
| `tool_choice`, images, `thinking` enable/disable | ✅ | ✅ | ❌ |
| Message content | ✅ | ✅ | ❌ |

Implication: you can change `tool_choice` per-request or toggle `thinking` without losing the tools+system cache. Don't over-worry about these — only tool-definition and model changes force a full rebuild.

---

## 20-block lookback window

Each breakpoint walks backward **at most 20 content blocks** to find a prior cache entry. If a single turn adds more than 20 blocks (common in agentic loops with many tool_use/tool_result pairs), the next request's breakpoint won't find the previous cache and silently misses.

Fix: place an intermediate breakpoint every ~15 blocks in long turns, or put the marker on a block that's within 20 of the previous turn's last cached block.

---

## Concurrent-request timing

A cache entry becomes readable only after the first response **begins streaming**. N parallel requests with identical prefixes all pay full price — none can read what the others are still writing.

For fan-out patterns: send 1 request, await the first streamed token (not the full response), then fire the remaining N−1. They'll read the cache the first one just wrote.

## Pre-warming the cache

To eliminate the cache-miss latency on the *first* real request, send a **`max_tokens: 0`** request at startup (or on an interval). The API runs prefill — writing the cache at your `cache_control` breakpoint — and returns immediately with `content: []`, `stop_reason: "max_tokens"`, and a populated `usage` block (zero output tokens billed; normal cache-write charge on `cache_creation_input_tokens`).

**When to pre-warm** — pre-warming trades a cache-write charge *now* for lower TTFT on the *next* real request. It's worth it when all three hold: (a) first-request latency is user-visible (chat/voice/interactive — not background jobs), (b) the shared prefix is large enough that a cold write is noticeably slow, and (c) there's a moment *before* traffic to fire it — app startup, worker boot, post-deploy, start of a scheduled window.

| Skip pre-warming when… | Because |
|---|---|
| Traffic is continuous (requests ≤ TTL apart) | The first real request warms the cache and every subsequent one hits it; a separate warm call is a pure extra write |
| The prefix is small or below the cacheable minimum | The cold-write penalty is negligible |
| The prefix varies per request/user | Nothing shared to pre-warm |
| You'd pre-warm many distinct prefixes speculatively | Each is a ~1.25× write; cost can exceed the latency you save |

**Scheduled re-warms:** only needed when traffic has gaps longer than the TTL. If real requests arrive more often than every 5 minutes, they keep the cache warm on their own — don't add an interval re-warm. For bursty traffic with long idle gaps, either re-warm just under the TTL or switch to `ttl: "1h"` and re-warm less often.

```python
client.messages.create(
    model="claude-opus-4-8",
    max_tokens=0,
    system=[{
        "type": "text",
        "text": SYSTEM_PROMPT,
        "cache_control": {"type": "ephemeral"},
    }],
    messages=[{"role": "user", "content": "warmup"}],
)
```

**Breakpoint placement:** put `cache_control` on the **last block shared with the real request** (the system prompt or tool definitions) — **not** on the placeholder user message, and **not** via top-level automatic caching (which would key the cache to the placeholder). The placeholder can be any non-whitespace string; it's read during prefill but never answered.

**Rejected combinations:** `max_tokens: 0` is an `invalid_request_error` with `stream: true`, `thinking.type: "enabled"`, `output_config.format`, `tool_choice` of `{"type":"tool"}` or `{"type":"any"}`, or inside a Message Batches request.

**TTL still applies** — re-warm at least every 5 minutes for the default cache, or use the 1-hour TTL. This replaces the older `max_tokens: 1` workaround (no single-token reply to discard, no output tokens billed, intent is unambiguous).

FILE:shared/token-counting.md
# Token Counting

Use the `count_tokens` endpoint (`POST /v1/messages/count_tokens`) for accurate
token counts against Claude models. Token counts are **model-specific** — pass
the same model ID you'll use for inference.

**Do not use `tiktoken`.** It's OpenAI's tokenizer. It undercounts Claude
tokens by ~15–20% on typical text, and by much more on code or non-English
input. Any estimate from `tiktoken`, `gpt-tokenizer`, or similar is wrong for
Claude.

## Count a file or string

```python
from anthropic import Anthropic

client = Anthropic()
resp = client.messages.count_tokens(
    model="claude-opus-4-8",
    messages=[{"role": "user", "content": open("CLAUDE.md").read()}],
)
print(resp.input_tokens)
```

TypeScript: `await client.messages.countTokens({model, messages})` →
`.input_tokens`. See `{lang}/claude-api/README.md` for other SDKs.

## CLI

```sh
ant messages count-tokens --model claude-opus-4-8 \
  --message '{role: user, content: "@./CLAUDE.md"}' \
  --transform input_tokens -r
```

## Diffing a file across two versions

The endpoint is stateless — count each version separately and subtract:

```python
from anthropic import Anthropic
import subprocess

client = Anthropic()
def count(text: str) -> int:
    return client.messages.count_tokens(
        model="claude-opus-4-8",
        messages=[{"role": "user", "content": text}],
    ).input_tokens

before = subprocess.check_output(["git", "show", "HEAD:CLAUDE.md"], text=True)
after = open("CLAUDE.md").read()
print(count(after) - count(before))
```

Full docs: see the Token Counting entry in `shared/live-sources.md`.

FILE:shared/tool-use-concepts.md
# Tool Use Concepts

This file covers the conceptual foundations of tool use with the Claude API. For language-specific code examples, see the `python/`, `typescript/`, or other language folders. For decision heuristics on which tools to expose, how to manage context in long-running agents, and caching strategy, see `agent-design.md`.

## User-Defined Tools

### Tool Definition Structure

> **Note:** When using the Tool Runner (beta), tool schemas are generated automatically from your function signatures (Python), Zod schemas (TypeScript), annotated classes (Java), `jsonschema` struct tags (Go), or `BaseTool` subclasses (Ruby). The raw JSON schema format below is for the manual approach — including PHP's `BetaRunnableTool`, which wraps a run closure around a hand-written schema — or SDKs without tool runner support.

Each tool requires a name, description, and JSON Schema for its inputs:

```json
{
  "name": "get_weather",
  "description": "Get current weather for a location",
  "input_schema": {
    "type": "object",
    "properties": {
      "location": {
        "type": "string",
        "description": "City and state, e.g., San Francisco, CA"
      },
      "unit": {
        "type": "string",
        "enum": ["celsius", "fahrenheit"],
        "description": "Temperature unit"
      }
    },
    "required": ["location"]
  }
}
```

**Best practices for tool definitions:**

- Use clear, descriptive names (e.g., `get_weather`, `search_database`, `send_email`)
- Write detailed descriptions — Claude uses these to decide when to use the tool. Be **prescriptive about *when* to call it**, not just what it does (e.g. "Call this when the user asks about current prices or recent events"). On recent Opus models, which reach for tools more conservatively, trigger conditions in the description give measurable lift in should-call rate.
- Include descriptions for each property
- Use `enum` for parameters with a fixed set of values
- Mark truly required parameters in `required`; make others optional with defaults

---

### Tool Choice Options

Control when Claude uses tools:

| Value                             | Behavior                                      |
| --------------------------------- | --------------------------------------------- |
| `{"type": "auto"}`                | Claude decides whether to use tools (default) |
| `{"type": "any"}`                 | Claude must use at least one tool             |
| `{"type": "tool", "name": "..."}` | Claude must use the specified tool            |
| `{"type": "none"}`                | Claude cannot use tools                       |

Any `tool_choice` value can also include `"disable_parallel_tool_use": true` to force Claude to use at most one tool per response. By default, Claude may request multiple tool calls in a single response.

---

### Tool Runner vs Manual Loop

**Tool Runner (Recommended):** The SDK's tool runner handles the agentic loop automatically — it calls the API, detects tool use requests, executes your tool functions, feeds results back to Claude, and repeats until Claude stops calling tools. Available in Python, TypeScript, Java, Go, Ruby, and PHP SDKs (beta). The Python SDK also provides MCP conversion helpers (`anthropic.lib.tools.mcp`) to convert MCP tools, prompts, and resources for use with the tool runner — see `python/claude-api/tool-use.md` for details.

**Manual Agentic Loop:** Use when you need fine-grained control over the loop (e.g., custom logging, conditional tool execution, human-in-the-loop approval). Loop until `stop_reason == "end_turn"`, always append the full `response.content` to preserve tool_use blocks, and ensure each `tool_result` includes the matching `tool_use_id`.

**Stop reasons for server-side tools:** When using server-side tools (code execution, web search, etc.), the API runs a server-side sampling loop. If this loop reaches its default limit of 10 iterations, the response will have `stop_reason: "pause_turn"`. To continue, re-send the user message and assistant response and make another API request — the server will resume where it left off. Do NOT add an extra user message like "Continue." — the API detects the trailing `server_tool_use` block and knows to resume automatically.

```python
# Handle pause_turn in your agentic loop
if response.stop_reason == "pause_turn":
    messages = [
        {"role": "user", "content": user_query},
        {"role": "assistant", "content": response.content},
    ]
    # Make another API request — server resumes automatically
    response = client.messages.create(
        model="claude-opus-4-8", messages=messages, tools=tools
    )
```

Set a `max_continuations` limit (e.g., 5) to prevent infinite loops. For the full guide, see: `https://platform.claude.com/docs/en/build-with-claude/handling-stop-reasons`

> **Security:** The tool runner executes your tool functions automatically whenever Claude requests them. For tools with side effects (sending emails, modifying databases, financial transactions), validate inputs within your tool functions and consider requiring confirmation for destructive operations. Use the manual agentic loop if you need human-in-the-loop approval before each tool execution.

---

### Handling Tool Results

When Claude uses a tool, the response contains a `tool_use` block. You must:

1. Execute the tool with the provided input
2. Send the result back in a `tool_result` message
3. Continue the conversation

**Error handling in tool results:** When a tool execution fails, set `"is_error": true` and provide an informative error message. Claude will typically acknowledge the error and either try a different approach or ask for clarification.

**Multiple tool calls:** Claude can request multiple tools in a single response. Handle them all before continuing — send all results back in a single `user` message.

---

## Server-Side Tools: Code Execution

The code execution tool lets Claude run code in a secure, sandboxed container. Unlike user-defined tools, server-side tools run on Anthropic's infrastructure — you don't execute anything client-side. Just include the tool definition and Claude handles the rest.

### Key Facts

- Runs in an isolated container (1 CPU, 5 GiB RAM, 5 GiB disk)
- No internet access (fully sandboxed)
- Python 3.11 with data science libraries pre-installed
- Containers persist for 30 days and can be reused across requests
- Free when used with web search/web fetch tools; otherwise $0.05/hour after 1,550 free hours/month per organization

### Tool Definition

The tool requires no schema — just declare it in the `tools` array:

```json
{
  "type": "code_execution_20260120",
  "name": "code_execution"
}
```

Claude automatically gains access to `bash_code_execution` (run shell commands) and `text_editor_code_execution` (create/view/edit files).

### Pre-installed Python Libraries

- **Data science**: pandas, numpy, scipy, scikit-learn, statsmodels
- **Visualization**: matplotlib, seaborn
- **File processing**: openpyxl, xlsxwriter, pillow, pypdf, pdfplumber, python-docx, python-pptx
- **Math**: sympy, mpmath
- **Utilities**: tqdm, python-dateutil, pytz, sqlite3

Additional packages can be installed at runtime via `pip install`.

### Supported File Types for Upload

| Type   | Extensions                         |
| ------ | ---------------------------------- |
| Data   | CSV, Excel (.xlsx/.xls), JSON, XML |
| Images | JPEG, PNG, GIF, WebP               |
| Text   | .txt, .md, .py, .js, etc.          |

### Container Reuse

Reuse containers across requests to maintain state (files, installed packages, variables). Extract the `container_id` from the first response and pass it to subsequent requests.

### Response Structure

The response contains interleaved text and tool result blocks:

- `text` — Claude's explanation
- `server_tool_use` — What Claude is doing
- `bash_code_execution_tool_result` — Code execution output (check `return_code` for success/failure)
- `text_editor_code_execution_tool_result` — File operation results

> **Security:** Always sanitize filenames with `os.path.basename()` / `path.basename()` before writing downloaded files to disk to prevent path traversal attacks. Write files to a dedicated output directory.

---

## Server-Side Tools: Web Search and Web Fetch

Web search and web fetch let Claude search the web and retrieve page content. They run server-side — just include the tool definitions and Claude handles queries, fetching, and result processing automatically.

### Tool Definitions

```json
[
  { "type": "web_search_20260209", "name": "web_search" },
  { "type": "web_fetch_20260209", "name": "web_fetch" }
]
```

### Dynamic Filtering (Fable 5 / Opus 4.8 / Opus 4.7 / Opus 4.6 / Sonnet 4.6)

The `web_search_20260209` and `web_fetch_20260209` versions support **dynamic filtering** — Claude writes and executes code to filter search results before they reach the context window, improving accuracy and token efficiency. Dynamic filtering is built into these tool versions and activates automatically; you do not need to separately declare the `code_execution` tool or pass any beta header.

```json
{
  "tools": [
    { "type": "web_search_20260209", "name": "web_search" },
    { "type": "web_fetch_20260209", "name": "web_fetch" }
  ]
}
```

Without dynamic filtering, the previous `web_search_20250305` version is also available.

> **Note:** Only include the standalone `code_execution` tool when your application needs code execution for its own purposes (data analysis, file processing, visualization) independent of web search. Including it alongside `_20260209` web tools creates a second execution environment that can confuse the model.

---

## Server-Side Tools: Programmatic Tool Calling

With standard tool use, each tool call is a round trip: Claude calls, the result enters Claude's context, Claude reasons, then calls the next tool. Chained calls accumulate latency and tokens — most of that intermediate data is never needed again.

Programmatic tool calling lets Claude compose those calls into a script. The script runs in the code execution container; when it invokes a tool, the container pauses, the call executes, and the result returns to the running code (not to Claude's context). The script processes it with normal control flow. Only the final output returns to Claude. Use it when chaining many tool calls or when intermediate results are large and should be filtered before reaching the context window.

For full documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/agents-and-tools/tool-use/programmatic-tool-calling`

---

## Server-Side Tools: Tool Search

The tool search tool lets Claude dynamically discover tools from large libraries without loading all definitions into the context window. Use it when you have many tools but only a few are relevant to any given request. Discovered tool schemas are appended to the request, not swapped in — this preserves the prompt cache (see `agent-design.md` §Caching for Agents).

For full documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-search-tool`

---

## Skills

Skills package task-specific instructions that Claude loads only when relevant. Each skill is a folder containing a `SKILL.md` file. The skill's short description sits in context by default; Claude reads the full file when the current task calls for it. Use skills to keep specialized instructions out of the base system prompt without losing discoverability.

For full documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/agents-and-tools/skills`

---

## Tool Use Examples

You can provide sample tool calls directly in your tool definitions to demonstrate usage patterns and reduce parameter errors. This helps Claude understand how to correctly format tool inputs, especially for tools with complex schemas.

For full documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/agents-and-tools/tool-use/implement-tool-use`

---

## Server-Side Tools: Computer Use

Computer use lets Claude interact with a desktop environment (screenshots, mouse, keyboard). It can be Anthropic-hosted (server-side, like code execution) or self-hosted (you provide the environment and execute actions client-side).

For full documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/agents-and-tools/computer-use/overview`

---

## Context Editing

Context editing clears stale tool results and thinking blocks from the transcript as a long-running agent accumulates turns. Unlike compaction (which summarizes), context editing prunes — the cleared content is removed, not replaced. Use it when old tool outputs are no longer relevant and you want to keep the transcript lean without losing the conversation structure. Thresholds for what to clear are configurable.

For full documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/build-with-claude/context-editing`

---

## Server-Side Tools: Advisor (Beta)

The advisor tool lets Claude consult a secondary model during a conversation. The advisor runs its own API call with a model you specify and returns its analysis to the primary model. Use it when you want a second opinion, specialized expertise, or cross-model verification without managing the orchestration yourself.

### Tool Definition

```json
{
  "type": "advisor_20260301",
  "name": "advisor",
  "model": "claude-sonnet-4-6"
}
```

The `model` parameter is required — it specifies which model the advisor uses for its own inference. Optional fields: `caching`, `max_uses`, `allowed_callers`, `defer_loading`, `strict`.

**Beta header required:** `advisor-tool-2026-03-01`. The SDK sets this automatically when using `client.beta.messages.create()` with advisor tools.

---

## Client-Side Tools: Memory

The memory tool enables Claude to store and retrieve information across conversations through a memory file directory. Claude can create, read, update, and delete files that persist between sessions.

### Key Facts

- Client-side tool — you control storage via your implementation
- Supports commands: `view`, `create`, `str_replace`, `insert`, `delete`, `rename`
- Operates on files in a `/memories` directory
- The Python, TypeScript, and Java SDKs provide helper classes/functions for implementing the memory backend

> **Security:** Never store API keys, passwords, tokens, or other secrets in memory files. Be cautious with personally identifiable information (PII) — check data privacy regulations (GDPR, CCPA) before persisting user data. The reference implementations have no built-in access control; in multi-user systems, implement per-user memory directories and authentication in your tool handlers.

For full implementation examples, use WebFetch:

- Docs: `https://platform.claude.com/docs/en/agents-and-tools/tool-use/memory-tool.md`

---

## Structured Outputs

Structured outputs constrain Claude's responses to follow a specific JSON schema, guaranteeing valid, parseable output. This is not a separate tool — it enhances the Messages API response format and/or tool parameter validation.

Two features are available:

- **JSON outputs** (`output_config.format`): Control Claude's response format
- **Strict tool use** (`strict: true`): Guarantee valid tool parameter schemas

**Supported models:** Claude Fable 5, Claude Opus 4.8, Claude Sonnet 4.6, and Claude Haiku 4.5. Legacy models (Claude Opus 4.5, Claude Opus 4.1) also support structured outputs.

> **Recommended:** Use `client.messages.parse()` which automatically validates responses against your schema. When using `messages.create()` directly, use `output_config: {format: {...}}`. The `output_format` convenience parameter is also accepted by some SDK methods (e.g., `.parse()`), but `output_config.format` is the canonical API-level parameter.

### JSON Schema Limitations

**Supported:**

- Basic types: object, array, string, integer, number, boolean, null
- `enum`, `const`, `anyOf`, `allOf`, `$ref`/`$def`
- String formats: `date-time`, `time`, `date`, `duration`, `email`, `hostname`, `uri`, `ipv4`, `ipv6`, `uuid`
- `additionalProperties: false` (required for all objects)

**Not supported:**

- Recursive schemas
- Numerical constraints (`minimum`, `maximum`, `multipleOf`)
- String constraints (`minLength`, `maxLength`)
- Complex array constraints
- `additionalProperties` set to anything other than `false`

The Python and TypeScript SDKs automatically handle unsupported constraints by removing them from the schema sent to the API and validating them client-side.

### Important Notes

- **First request latency**: New schemas incur a one-time compilation cost. Subsequent requests with the same schema use a 24-hour cache.
- **Refusals**: If Claude refuses for safety reasons (`stop_reason: "refusal"`), the output may not match your schema.
- **Token limits**: If `stop_reason: "max_tokens"`, output may be incomplete. Increase `max_tokens`.
- **Incompatible with**: Citations (returns 400 error), message prefilling.
- **Works with**: Batches API, streaming, token counting, extended thinking.

---

## Tips for Effective Tool Use

1. **Provide detailed descriptions**: Claude relies heavily on descriptions to understand when and how to use tools
2. **Use specific tool names**: `get_current_weather` is better than `weather`
3. **Validate inputs**: Always validate tool inputs before execution
4. **Handle errors gracefully**: Return informative error messages so Claude can adapt
5. **Limit tool count**: Too many tools can confuse the model — keep the set focused
6. **Test tool interactions**: Verify Claude uses tools correctly in various scenarios

For detailed tool use documentation, use WebFetch:

- URL: `https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview`

FILE:typescript/claude-api/batches.md
# Message Batches API — TypeScript

The Batches API (`POST /v1/messages/batches`) processes Messages API requests asynchronously at 50% of standard prices.

## Key Facts

- Up to 100,000 requests or 256 MB per batch
- Most batches complete within 1 hour; maximum 24 hours
- Results available for 29 days after creation
- 50% cost reduction on all token usage
- All Messages API features supported (vision, tools, caching, etc.)

---

## Create a Batch

```typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();

const messageBatch = await client.messages.batches.create({
  requests: [
    {
      custom_id: "request-1",
      params: {
        model: "claude-opus-4-8",
        max_tokens: 16000,
        messages: [
          { role: "user", content: "Summarize climate change impacts" },
        ],
      },
    },
    {
      custom_id: "request-2",
      params: {
        model: "claude-opus-4-8",
        max_tokens: 16000,
        messages: [
          { role: "user", content: "Explain quantum computing basics" },
        ],
      },
    },
  ],
});

console.log(`Batch ID: messageBatch.id`);
console.log(`Status: messageBatch.processing_status`);
```

---

## Poll for Completion

```typescript
let batch;
while (true) {
  batch = await client.messages.batches.retrieve(messageBatch.id);
  if (batch.processing_status === "ended") break;
  console.log(
    `Status: batch.processing_status, processing: batch.request_counts.processing`,
  );
  await new Promise((resolve) => setTimeout(resolve, 60_000));
}

console.log("Batch complete!");
console.log(`Succeeded: batch.request_counts.succeeded`);
console.log(`Errored: batch.request_counts.errored`);
```

---

## Retrieve Results

```typescript
for await (const result of await client.messages.batches.results(
  messageBatch.id,
)) {
  switch (result.result.type) {
    case "succeeded":
      console.log(
        `[result.custom_id] result.result.message.content[0].text.slice(0, 100)`,
      );
      break;
    case "errored":
      if (result.result.error.type === "invalid_request") {
        console.log(`[result.custom_id] Validation error - fix and retry`);
      } else {
        console.log(`[result.custom_id] Server error - safe to retry`);
      }
      break;
    case "expired":
      console.log(`[result.custom_id] Expired - resubmit`);
      break;
  }
}
```

---

## Cancel a Batch

```typescript
const cancelled = await client.messages.batches.cancel(messageBatch.id);
console.log(`Status: cancelled.processing_status`); // "canceling"
```

FILE:typescript/claude-api/files-api.md
# Files API — TypeScript

The Files API uploads files for use in Messages API requests. Reference files via `file_id` in content blocks, avoiding re-uploads across multiple API calls.

**Beta:** Pass `betas: ["files-api-2025-04-14"]` in your API calls (the SDK sets the required header automatically).

## Key Facts

- Maximum file size: 500 MB
- Total storage: 100 GB per organization
- Files persist until deleted
- File operations (upload, list, delete) are free; content used in messages is billed as input tokens
- Not available on Amazon Bedrock or Google Vertex AI

---

## Upload a File

```typescript
import Anthropic, { toFile } from "@anthropic-ai/sdk";
import fs from "fs";

const client = new Anthropic();

const uploaded = await client.beta.files.upload({
  file: await toFile(fs.createReadStream("report.pdf"), undefined, {
    type: "application/pdf",
  }),
  betas: ["files-api-2025-04-14"],
});

console.log(`File ID: uploaded.id`);
console.log(`Size: uploaded.size_bytes bytes`);
```

---

## Use a File in Messages

### PDF / Text Document

```typescript
const response = await client.beta.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: [
        { type: "text", text: "Summarize the key findings in this report." },
        {
          type: "document",
          source: { type: "file", file_id: uploaded.id },
          title: "Q4 Report",
          citations: { enabled: true },
        },
      ],
    },
  ],
  betas: ["files-api-2025-04-14"],
});

console.log(response.content[0].text);
```

---

## Manage Files

### List Files

```typescript
const files = await client.beta.files.list({
  betas: ["files-api-2025-04-14"],
});
for (const f of files.data) {
  console.log(`f.id: f.filename (f.size_bytes bytes)`);
}
```

### Delete a File

```typescript
await client.beta.files.delete("file_011CNha8iCJcU1wXNR6q4V8w", {
  betas: ["files-api-2025-04-14"],
});
```

### Download a File

```typescript
const response = await client.beta.files.download(
  "file_011CNha8iCJcU1wXNR6q4V8w",
  { betas: ["files-api-2025-04-14"] },
);
const content = Buffer.from(await response.arrayBuffer());
await fs.promises.writeFile("output.txt", content);
```

FILE:typescript/claude-api/README.md
# Claude API — TypeScript

## Installation

```bash
npm install @anthropic-ai/sdk
```

## Client Initialization

```typescript
import Anthropic from "@anthropic-ai/sdk";

// Default — resolves credentials from the environment:
// ANTHROPIC_API_KEY, or ANTHROPIC_AUTH_TOKEN, or an `ant auth login` profile.
// Prefer this for local dev; don't hardcode a key.
const client = new Anthropic();

// Explicit API key (only when you must inject a specific key)
const client = new Anthropic({ apiKey: "your-api-key" });
```

---

## Basic Message Request

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [{ role: "user", content: "What is the capital of France?" }],
});
// response.content is ContentBlock[] — a discriminated union. Narrow by .type
// before accessing .text (TypeScript will error on content[0].text without this).
for (const block of response.content) {
  if (block.type === "text") {
    console.log(block.text);
  }
}
```

---

## System Prompts

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  system:
    "You are a helpful coding assistant. Always provide examples in Python.",
  messages: [{ role: "user", content: "How do I read a JSON file?" }],
});
```

### Mid-conversation system messages (beta, model-gated)

For operator instructions that arrive mid-conversation (mode switches, injected state), append `{role: "system", ...}` to `messages` instead of editing top-level `system` — this preserves the cached prefix and carries operator authority. Must follow a user message; cannot be `messages[0]`. Unsupported models return a 400 (`role 'system' is not supported on this model`). See `shared/prompt-caching.md` for when to use this vs. top-level `system`.

```typescript
// SDK types for role:"system" in messages are pending — pass the beta header
// directly until the SDK updates, then switch to client.beta.messages.create
// with betas: ["mid-conversation-system-2026-04-07"].
const response = await client.messages.create(
  {
    model: MODEL_ID, // must support mid-conversation system messages
    max_tokens: 16000,
    system: [
      { type: "text", text: STABLE_SYSTEM, cache_control: { type: "ephemeral" } },
    ],
    messages: [
      ...history,
      { role: "user", content: userMessage },
      // @ts-expect-error — role:"system" pending SDK types
      { role: "system", content: "Terse mode enabled — keep responses under 40 words." },
    ],
  },
  { headers: { "anthropic-beta": "mid-conversation-system-2026-04-07" } },
);
```

---

## Vision (Images)

### URL

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: [
        {
          type: "image",
          source: { type: "url", url: "https://example.com/image.png" },
        },
        { type: "text", text: "Describe this image" },
      ],
    },
  ],
});
```

### Base64

```typescript
import fs from "fs";

const imageData = fs.readFileSync("image.png").toString("base64");

const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: [
        {
          type: "image",
          source: { type: "base64", media_type: "image/png", data: imageData },
        },
        { type: "text", text: "What's in this image?" },
      ],
    },
  ],
});
```

---

## Prompt Caching

**Caching is a prefix match** — any byte change anywhere in the prefix invalidates everything after it. For placement patterns, architectural guidance (frozen system prompt, deterministic tool order, where to put volatile content), and the silent-invalidator audit checklist, read `shared/prompt-caching.md`.

### Automatic Caching (Recommended)

Use top-level `cache_control` to automatically cache the last cacheable block in the request:

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  cache_control: { type: "ephemeral" }, // auto-caches the last cacheable block
  system: "You are an expert on this large document...",
  messages: [{ role: "user", content: "Summarize the key points" }],
});
```

### Manual Cache Control

For fine-grained control, add `cache_control` to specific content blocks:

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  system: [
    {
      type: "text",
      text: "You are an expert on this large document...",
      cache_control: { type: "ephemeral" }, // default TTL is 5 minutes
    },
  ],
  messages: [{ role: "user", content: "Summarize the key points" }],
});

// With explicit TTL (time-to-live)
const response2 = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  system: [
    {
      type: "text",
      text: "You are an expert on this large document...",
      cache_control: { type: "ephemeral", ttl: "1h" }, // 1 hour TTL
    },
  ],
  messages: [{ role: "user", content: "Summarize the key points" }],
});
```

### Verifying Cache Hits

```typescript
console.log(response.usage.cache_creation_input_tokens); // tokens written to cache (~1.25x cost)
console.log(response.usage.cache_read_input_tokens);     // tokens served from cache (~0.1x cost)
console.log(response.usage.input_tokens);                // uncached tokens (full cost)
```

If `cache_read_input_tokens` is zero across repeated identical-prefix requests, a silent invalidator is at work — `Date.now()` or a UUID in the system prompt, non-deterministic key ordering, or a varying tool set. See `shared/prompt-caching.md` for the full audit table.

---

## Extended Thinking

> **Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6:** Use adaptive thinking. `budget_tokens` is removed on Fable 5, Opus 4.8, and 4.7 (400 if sent); deprecated on Opus 4.6 and Sonnet 4.6.
> **Older models:** Use `thinking: {type: "enabled", budget_tokens: N}` (must be < `max_tokens`, min 1024).

```typescript
// Fable 5 / Opus 4.8 / 4.7 / 4.6: adaptive thinking (recommended)
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  thinking: { type: "adaptive" },
  output_config: { effort: "high" }, // low | medium | high | max
  messages: [
    { role: "user", content: "Solve this math problem step by step..." },
  ],
});

for (const block of response.content) {
  if (block.type === "thinking") {
    console.log("Thinking:", block.thinking);
  } else if (block.type === "text") {
    console.log("Response:", block.text);
  }
}
```

---

## Error Handling

Use the SDK's typed exception classes — never check error messages with string matching:

```typescript
import Anthropic from "@anthropic-ai/sdk";

try {
  const response = await client.messages.create({...});
} catch (error) {
  if (error instanceof Anthropic.BadRequestError) {
    console.error("Bad request:", error.message);
  } else if (error instanceof Anthropic.AuthenticationError) {
    console.error("Invalid API key");
  } else if (error instanceof Anthropic.RateLimitError) {
    console.error("Rate limited - retry later");
  } else if (error instanceof Anthropic.APIError) {
    console.error(`API error error.status:`, error.message);
  }
}
```

All classes extend `Anthropic.APIError` with a typed `status` field. Check from most specific to least specific. See [shared/error-codes.md](../../shared/error-codes.md) for the full error code reference.

---

## Multi-Turn Conversations

The API is stateless — send the full conversation history each time. Use `Anthropic.MessageParam[]` to type the messages array:

```typescript
const messages: Anthropic.MessageParam[] = [
  { role: "user", content: "My name is Alice." },
  { role: "assistant", content: "Hello Alice! Nice to meet you." },
  { role: "user", content: "What's my name?" },
];

const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: messages,
});
```

**Rules:**

- Consecutive same-role messages are allowed — the API combines them into a single turn
- First message must be `user`
- Use SDK types (`Anthropic.MessageParam`, `Anthropic.Message`, `Anthropic.Tool`, etc.) for all API data structures — don't redefine equivalent interfaces

---

### Compaction (long conversations)

> **Beta, Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6.** When conversations approach the 200K context window, compaction automatically summarizes earlier context server-side. The API returns a `compaction` block; you must pass it back on subsequent requests — append `response.content`, not just the text.

```typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();
const messages: Anthropic.Beta.BetaMessageParam[] = [];

async function chat(userMessage: string): Promise<string> {
  messages.push({ role: "user", content: userMessage });

  const response = await client.beta.messages.create({
    betas: ["compact-2026-01-12"],
    model: "claude-opus-4-8",
    max_tokens: 16000,
    messages,
    context_management: {
      edits: [{ type: "compact_20260112" }],
    },
  });

  // Append full content — compaction blocks must be preserved
  messages.push({ role: "assistant", content: response.content });

  const textBlock = response.content.find(
    (b): b is Anthropic.Beta.BetaTextBlock => b.type === "text",
  );
  return textBlock?.text ?? "";
}

// Compaction triggers automatically when context grows large
console.log(await chat("Help me build a Python web scraper"));
console.log(await chat("Add support for JavaScript-rendered pages"));
console.log(await chat("Now add rate limiting and error handling"));
```

---

## Stop Reasons

The `stop_reason` field in the response indicates why the model stopped generating:

| Value           | Meaning                                                         |
| --------------- | --------------------------------------------------------------- |
| `end_turn`      | Claude finished its response naturally                          |
| `max_tokens`    | Hit the `max_tokens` limit — increase it or use streaming       |
| `stop_sequence` | Hit a custom stop sequence                                      |
| `tool_use`      | Claude wants to call a tool — execute it and continue           |
| `pause_turn`    | Model paused and can be resumed (agentic flows)                 |
| `refusal`       | Claude refused for safety reasons — check `stop_details`        |

### Structured Stop Details

When `stop_reason` is `"refusal"`, the response includes a `stop_details` object with structured information about the refusal:

```typescript
if (response.stop_reason === "refusal" && response.stop_details) {
  console.log(`Category: response.stop_details.category`); // "cyber" | "bio" | null
  console.log(`Explanation: response.stop_details.explanation`);
}
```

---

## Cost Optimization Strategies

### 1. Use Prompt Caching for Repeated Context

```typescript
// Automatic caching (simplest — caches the last cacheable block)
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  cache_control: { type: "ephemeral" },
  system: largeDocumentText, // e.g., 50KB of context
  messages: [{ role: "user", content: "Summarize the key points" }],
});

// First request: full cost
// Subsequent requests: ~90% cheaper for cached portion
```

### 2. Use Token Counting Before Requests

```typescript
const countResponse = await client.messages.countTokens({
  model: "claude-opus-4-8",
  messages: messages,
  system: system,
});

const estimatedInputCost = countResponse.input_tokens * 0.000005; // $5/1M tokens
console.log(`Estimated input cost: $estimatedInputCost.toFixed(4)`);
```

FILE:typescript/claude-api/streaming.md
# Streaming — TypeScript

## Quick Start

```typescript
const stream = client.messages.stream({
  model: "claude-opus-4-8",
  max_tokens: 64000,
  messages: [{ role: "user", content: "Write a story" }],
});

for await (const event of stream) {
  if (
    event.type === "content_block_delta" &&
    event.delta.type === "text_delta"
  ) {
    process.stdout.write(event.delta.text);
  }
}
```

---

## Handling Different Content Types

> **Fable 5 / Opus 4.8 / Opus 4.7 / Opus 4.6:** Use `thinking: {type: "adaptive"}`. On older models, use `thinking: {type: "enabled", budget_tokens: N}` instead.

```typescript
const stream = client.messages.stream({
  model: "claude-opus-4-8",
  max_tokens: 64000,
  thinking: { type: "adaptive" },
  messages: [{ role: "user", content: "Analyze this problem" }],
});

for await (const event of stream) {
  switch (event.type) {
    case "content_block_start":
      switch (event.content_block.type) {
        case "thinking":
          console.log("\n[Thinking...]");
          break;
        case "text":
          console.log("\n[Response:]");
          break;
      }
      break;
    case "content_block_delta":
      switch (event.delta.type) {
        case "thinking_delta":
          process.stdout.write(event.delta.thinking);
          break;
        case "text_delta":
          process.stdout.write(event.delta.text);
          break;
      }
      break;
  }
}
```

---

## Streaming with Tool Use (Tool Runner)

Use the tool runner with `stream: true`. The outer loop iterates over tool runner iterations (messages), the inner loop processes stream events:

```typescript
import Anthropic from "@anthropic-ai/sdk";
import { betaZodTool } from "@anthropic-ai/sdk/helpers/beta/zod";
import { z } from "zod";

const client = new Anthropic();

const getWeather = betaZodTool({
  name: "get_weather",
  description: "Get current weather for a location",
  inputSchema: z.object({
    location: z.string().describe("City and state, e.g., San Francisco, CA"),
  }),
  run: async ({ location }) => `72°F and sunny in location`,
});

const runner = client.beta.messages.toolRunner({
  model: "claude-opus-4-8",
  max_tokens: 64000,
  tools: [getWeather],
  messages: [
    { role: "user", content: "What's the weather in Paris and London?" },
  ],
  stream: true,
});

// Outer loop: each tool runner iteration
for await (const messageStream of runner) {
  // Inner loop: stream events for this iteration
  for await (const event of messageStream) {
    switch (event.type) {
      case "content_block_delta":
        switch (event.delta.type) {
          case "text_delta":
            process.stdout.write(event.delta.text);
            break;
          case "input_json_delta":
            // Tool input being streamed
            break;
        }
        break;
    }
  }
}
```

---

## Getting the Final Message

```typescript
const stream = client.messages.stream({
  model: "claude-opus-4-8",
  max_tokens: 64000,
  messages: [{ role: "user", content: "Hello" }],
});

for await (const event of stream) {
  // Process events...
}

const finalMessage = await stream.finalMessage();
console.log(`Tokens used: finalMessage.usage.output_tokens`);
```

---

## Stream Event Types

| Event Type            | Description                 | When it fires                     |
| --------------------- | --------------------------- | --------------------------------- |
| `message_start`       | Contains message metadata   | Once at the beginning             |
| `content_block_start` | New content block beginning | When a text/tool_use block starts |
| `content_block_delta` | Incremental content update  | For each token/chunk              |
| `content_block_stop`  | Content block complete      | When a block finishes             |
| `message_delta`       | Message-level updates       | Contains `stop_reason`, usage     |
| `message_stop`        | Message complete            | Once at the end                   |

## Best Practices

1. **Always flush output** — Use `process.stdout.write()` for immediate display
2. **Handle partial responses** — If the stream is interrupted, you may have incomplete content
3. **Track token usage** — The `message_delta` event contains usage information
4. **Use `finalMessage()`** — Get the complete `Anthropic.Message` object even when streaming. Don't wrap `.on()` events in `new Promise()` — `finalMessage()` handles all completion/error/abort states internally
5. **Buffer for web UIs** — Consider buffering a few tokens before rendering to avoid excessive DOM updates
6. **Use `stream.on("text", ...)` for deltas** — The `text` event provides just the delta string, simpler than manually filtering `content_block_delta` events
7. **For agentic loops with streaming** — See the [Streaming Manual Loop](./tool-use.md#streaming-manual-loop) section in tool-use.md for combining `stream()` + `finalMessage()` with a tool-use loop

## Raw SSE Format

If using raw HTTP (not SDKs), the stream returns Server-Sent Events:

```
event: message_start
data: {"type":"message_start","message":{"id":"msg_...","type":"message",...}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Hello"}}

event: content_block_stop
data: {"type":"content_block_stop","index":0}

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn"},"usage":{"output_tokens":12}}

event: message_stop
data: {"type":"message_stop"}
```

FILE:typescript/claude-api/tool-use.md
# Tool Use — TypeScript

For conceptual overview (tool definitions, tool choice, tips), see [shared/tool-use-concepts.md](../../shared/tool-use-concepts.md).

## Tool Runner (Recommended)

**Beta:** The tool runner is in beta in the TypeScript SDK.

Use `betaZodTool` with Zod schemas to define tools with a `run` function, then pass them to `client.beta.messages.toolRunner()`:

```typescript
import Anthropic from "@anthropic-ai/sdk";
import { betaZodTool } from "@anthropic-ai/sdk/helpers/beta/zod";
import { z } from "zod";

const client = new Anthropic();

const getWeather = betaZodTool({
  name: "get_weather",
  description: "Get current weather for a location",
  inputSchema: z.object({
    location: z.string().describe("City and state, e.g., San Francisco, CA"),
    unit: z.enum(["celsius", "fahrenheit"]).optional(),
  }),
  run: async (input) => {
    // Your implementation here
    return `72°F and sunny in input.location`;
  },
});

// The tool runner handles the agentic loop and returns the final message
const finalMessage = await client.beta.messages.toolRunner({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  tools: [getWeather],
  messages: [{ role: "user", content: "What's the weather in Paris?" }],
});

console.log(finalMessage.content);
```

**Key benefits of the tool runner:**

- No manual loop — the SDK handles calling tools and feeding results back
- Type-safe tool inputs via Zod schemas
- Tool schemas are generated automatically from Zod definitions
- Iteration stops automatically when Claude has no more tool calls

---

## Manual Agentic Loop

Use this when you need fine-grained control (custom logging, conditional tool execution, streaming individual iterations, human-in-the-loop approval):

```typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();
const tools: Anthropic.Tool[] = [...]; // Your tool definitions
let messages: Anthropic.MessageParam[] = [{ role: "user", content: userInput }];

while (true) {
  const response = await client.messages.create({
    model: "claude-opus-4-8",
    max_tokens: 16000,
    tools: tools,
    messages: messages,
  });

  if (response.stop_reason === "end_turn") break;

  // Server-side tool hit iteration limit; append assistant turn and re-send to continue
  if (response.stop_reason === "pause_turn") {
    messages.push({ role: "assistant", content: response.content });
    continue;
  }

  const toolUseBlocks = response.content.filter(
    (b): b is Anthropic.ToolUseBlock => b.type === "tool_use",
  );

  messages.push({ role: "assistant", content: response.content });

  const toolResults: Anthropic.ToolResultBlockParam[] = [];
  for (const tool of toolUseBlocks) {
    const result = await executeTool(tool.name, tool.input);
    toolResults.push({
      type: "tool_result",
      tool_use_id: tool.id,
      content: result,
    });
  }

  messages.push({ role: "user", content: toolResults });
}
```

### Streaming Manual Loop

Use `client.messages.stream()` + `finalMessage()` instead of `.create()` when you need streaming within a manual loop. Text deltas are streamed on each iteration; `finalMessage()` collects the complete `Message` so you can inspect `stop_reason` and extract tool-use blocks:

```typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();
const tools: Anthropic.Tool[] = [...];
let messages: Anthropic.MessageParam[] = [{ role: "user", content: userInput }];

while (true) {
  const stream = client.messages.stream({
    model: "claude-opus-4-8",
    max_tokens: 64000,
    tools,
    messages,
  });

  // Stream text deltas on each iteration
  stream.on("text", (delta) => {
    process.stdout.write(delta);
  });

  // finalMessage() resolves with the complete Message — no need to
  // manually wire up .on("message") / .on("error") / .on("abort")
  const message = await stream.finalMessage();

  if (message.stop_reason === "end_turn") break;

  // Server-side tool hit iteration limit; append assistant turn and re-send to continue
  if (message.stop_reason === "pause_turn") {
    messages.push({ role: "assistant", content: message.content });
    continue;
  }

  const toolUseBlocks = message.content.filter(
    (b): b is Anthropic.ToolUseBlock => b.type === "tool_use",
  );

  messages.push({ role: "assistant", content: message.content });

  const toolResults: Anthropic.ToolResultBlockParam[] = [];
  for (const tool of toolUseBlocks) {
    const result = await executeTool(tool.name, tool.input);
    toolResults.push({
      type: "tool_result",
      tool_use_id: tool.id,
      content: result,
    });
  }

  messages.push({ role: "user", content: toolResults });
}
```

> **Important:** Don't wrap `.on()` events in `new Promise()` to collect the final message — use `stream.finalMessage()` instead. The SDK handles all error/abort/completion states internally.

> **Error handling in the loop:** Use the SDK's typed exceptions (e.g., `Anthropic.RateLimitError`, `Anthropic.APIError`) — see [Error Handling](./README.md#error-handling) for examples. Don't check error messages with string matching.

> **SDK types:** Use `Anthropic.MessageParam`, `Anthropic.Tool`, `Anthropic.ToolUseBlock`, `Anthropic.ToolResultBlockParam`, `Anthropic.Message`, etc. for all API-related data structures. Don't redefine equivalent interfaces.

---

## Handling Tool Results

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  tools: tools,
  messages: [{ role: "user", content: "What's the weather in Paris?" }],
});

for (const block of response.content) {
  if (block.type === "tool_use") {
    const result = await executeTool(block.name, block.input);

    const followup = await client.messages.create({
      model: "claude-opus-4-8",
      max_tokens: 16000,
      tools: tools,
      messages: [
        { role: "user", content: "What's the weather in Paris?" },
        { role: "assistant", content: response.content },
        {
          role: "user",
          content: [
            { type: "tool_result", tool_use_id: block.id, content: result },
          ],
        },
      ],
    });
  }
}
```

---

## Tool Choice

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  tools: tools,
  tool_choice: { type: "tool", name: "get_weather" },
  messages: [{ role: "user", content: "What's the weather in Paris?" }],
});
```

---

## Server-Side Tools

Version-suffixed `type` literals; `name` is fixed per interface. Pass plain object literals — the `ToolUnion` type is satisfied structurally. **The `name`/`type` pair must match the interface**: mixing `str_replace_based_edit_tool` (20250728 name) with `text_editor_20250124` (which expects `str_replace_editor`) is a TS2322.

**Don't type-annotate as `Tool[]`** — `Tool` is just the custom-tool variant. Let structural typing infer from the `tools` param, or annotate as `Anthropic.Messages.ToolUnion[]` if you must:

```typescript
// ✓ let inference work — no annotation
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  tools: [
    { type: "text_editor_20250728", name: "str_replace_based_edit_tool" },
    { type: "bash_20250124", name: "bash" },
    { type: "web_search_20260209", name: "web_search" },
    { type: "code_execution_20260120", name: "code_execution" },
  ],
  messages: [{ role: "user", content: "..." }],
});

// ✗ this is a TS2352 — Tool is the CUSTOM tool variant only
// const tools: Anthropic.Tool[] = [{ type: "text_editor_20250728", ... }]
```

| Interface | `name` | `type` |
|---|---|---|
| `ToolTextEditor20250124` | `str_replace_editor` | `text_editor_20250124` |
| `ToolTextEditor20250429` | `str_replace_based_edit_tool` | `text_editor_20250429` |
| `ToolTextEditor20250728` | `str_replace_based_edit_tool` | `text_editor_20250728` |
| `ToolBash20250124` | `bash` | `bash_20250124` |
| `WebSearchTool20260209` | `web_search` | `web_search_20260209` |
| `WebFetchTool20260209` | `web_fetch` | `web_fetch_20260209` |
| `CodeExecutionTool20260120` | `code_execution` | `code_execution_20260120` |

**Don't mix beta and non-beta types**: if you call `client.beta.messages.create()`, the response `content` is `BetaContentBlock[]` — you cannot pass that to a non-beta `ContentBlockParam[]` without narrowing each element.

---


## Code Execution

### Basic Usage

```typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();

const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content:
        "Calculate the mean and standard deviation of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]",
    },
  ],
  tools: [{ type: "code_execution_20260120", name: "code_execution" }],
});
```

### Reading Local Files (ESM note)

`__dirname` doesn't exist in ES modules. For script-relative paths use `import.meta.url`:

```typescript
import { readFileSync } from "fs";
import { fileURLToPath } from "url";
import { dirname, join } from "path";

const __dirname = dirname(fileURLToPath(import.meta.url));
const pdfBytes = readFileSync(join(__dirname, "sample.pdf"));
```

Or use a CWD-relative path if the script runs from a known directory: `readFileSync("./sample.pdf")`.

### Upload Files for Analysis

```typescript
import Anthropic, { toFile } from "@anthropic-ai/sdk";
import { createReadStream } from "fs";

const client = new Anthropic();

// 1. Upload a file
const uploaded = await client.beta.files.upload({
  file: await toFile(createReadStream("sales_data.csv"), undefined, {
    type: "text/csv",
  }),
  betas: ["files-api-2025-04-14"],
});

// 2. Pass to code execution
// Code execution is GA; Files API is still beta (pass via RequestOptions)
const response = await client.messages.create(
  {
    model: "claude-opus-4-8",
    max_tokens: 16000,
    messages: [
      {
        role: "user",
        content: [
          {
            type: "text",
            text: "Analyze this sales data. Show trends and create a visualization.",
          },
          { type: "container_upload", file_id: uploaded.id },
        ],
      },
    ],
    tools: [{ type: "code_execution_20260120", name: "code_execution" }],
  },
  { headers: { "anthropic-beta": "files-api-2025-04-14" } },
);
```

### Retrieve Generated Files

```typescript
import path from "path";
import fs from "fs";

const OUTPUT_DIR = "./claude_outputs";
await fs.promises.mkdir(OUTPUT_DIR, { recursive: true });

for (const block of response.content) {
  if (block.type === "bash_code_execution_tool_result") {
    const result = block.content;
    if (result.type === "bash_code_execution_result" && result.content) {
      for (const fileRef of result.content) {
        if (fileRef.type === "bash_code_execution_output") {
          const metadata = await client.beta.files.retrieveMetadata(
            fileRef.file_id,
          );
          const downloadResponse = await client.beta.files.download(fileRef.file_id);
          const fileBytes = Buffer.from(await downloadResponse.arrayBuffer());
          const safeName = path.basename(metadata.filename);
          if (!safeName || safeName === "." || safeName === "..") {
            console.warn(`Skipping invalid filename: metadata.filename`);
            continue;
          }
          const outputPath = path.join(OUTPUT_DIR, safeName);
          await fs.promises.writeFile(outputPath, fileBytes);
          console.log(`Saved: outputPath`);
        }
      }
    }
  }
}
```

### Container Reuse

```typescript
// First request: set up environment
const response1 = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: "Install tabulate and create data.json with sample user data",
    },
  ],
  tools: [{ type: "code_execution_20260120", name: "code_execution" }],
});

// Reuse container
// container is nullable — set only when using server-side code execution
const containerId = response1.container!.id;

const response2 = await client.messages.create({
  container: containerId,
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: "Read data.json and display as a formatted table",
    },
  ],
  tools: [{ type: "code_execution_20260120", name: "code_execution" }],
});
```

---

## Memory Tool

### Basic Usage

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: "Remember that my preferred language is TypeScript.",
    },
  ],
  tools: [{ type: "memory_20250818", name: "memory" }],
});
```

### SDK Memory Helper

Use `betaMemoryTool` with a `MemoryToolHandlers` implementation:

```typescript
import {
  betaMemoryTool,
  type MemoryToolHandlers,
} from "@anthropic-ai/sdk/helpers/beta/memory";

const handlers: MemoryToolHandlers = {
  async view(command) { ... },
  async create(command) { ... },
  async str_replace(command) { ... },
  async insert(command) { ... },
  async delete(command) { ... },
  async rename(command) { ... },
};

const memory = betaMemoryTool(handlers);

const runner = client.beta.messages.toolRunner({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  tools: [memory],
  messages: [{ role: "user", content: "Remember my preferences" }],
});

for await (const message of runner) {
  console.log(message);
}
```

For full implementation examples, use WebFetch:

- `https://github.com/anthropics/anthropic-sdk-typescript/blob/main/examples/tools-helpers-memory.ts`

---

## Structured Outputs

### JSON Outputs (Zod — Recommended)

```typescript
import Anthropic from "@anthropic-ai/sdk";
import { z } from "zod";
import { zodOutputFormat } from "@anthropic-ai/sdk/helpers/zod";

const ContactInfoSchema = z.object({
  name: z.string(),
  email: z.string(),
  plan: z.string(),
  interests: z.array(z.string()),
  demo_requested: z.boolean(),
});

const client = new Anthropic();

const response = await client.messages.parse({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content:
        "Extract: Jane Doe (jane@co.com) wants Enterprise, interested in API and SDKs, wants a demo.",
    },
  ],
  output_config: {
    format: zodOutputFormat(ContactInfoSchema),
  },
});

// parsed_output is null if parsing failed — assert or guard
console.log(response.parsed_output!.name); // "Jane Doe"
```

### Strict Tool Use

```typescript
const response = await client.messages.create({
  model: "claude-opus-4-8",
  max_tokens: 16000,
  messages: [
    {
      role: "user",
      content: "Book a flight to Tokyo for 2 passengers on March 15",
    },
  ],
  tools: [
    {
      name: "book_flight",
      description: "Book a flight to a destination",
      strict: true,
      input_schema: {
        type: "object",
        properties: {
          destination: { type: "string" },
          date: { type: "string", format: "date" },
          passengers: {
            type: "integer",
            enum: [1, 2, 3, 4, 5, 6, 7, 8],
          },
        },
        required: ["destination", "date", "passengers"],
        additionalProperties: false,
      },
    },
  ],
});
```

FILE:typescript/managed-agents/README.md
# Managed Agents — TypeScript

> **Bindings not shown here:** This README covers the most common managed-agents flows for TypeScript. If you need a class, method, namespace, field, or behavior that isn't shown, WebFetch the TypeScript SDK repo **or the relevant docs page** from `shared/live-sources.md` rather than guess. Do not extrapolate from cURL shapes or another language's SDK.

> **Agents are persistent — create once, reference by ID.** Store the agent ID returned by `agents.create` and pass it to every subsequent `sessions.create`; do not call `agents.create` in the request path. The Anthropic CLI is one convenient way to create agents and environments from version-controlled YAML — its URL is in `shared/live-sources.md`. The examples below show in-code creation for completeness; in production the create call belongs in setup, not in the request path.

## Installation

```bash
npm install @anthropic-ai/sdk
```

## Client Initialization

```typescript
import Anthropic from "@anthropic-ai/sdk";

// Default — resolves credentials from the environment:
// ANTHROPIC_API_KEY, or ANTHROPIC_AUTH_TOKEN, or an `ant auth login` profile.
// Prefer this for local dev; don't hardcode a key.
const client = new Anthropic();

// Explicit API key (only when you must inject a specific key)
const client = new Anthropic({ apiKey: "your-api-key" });
```

---

## Create an Environment

```typescript
const environment = await client.beta.environments.create(
  {
    name: "my-dev-env",
    config: {
      type: "cloud",
      networking: { type: "unrestricted" },
    },
  },
);
console.log(environment.id); // env_...
```

---

## Create an Agent (required first step)

> ⚠️ **There is no inline agent config.** `model`/`system`/`tools` live on the agent object, not the session. Always start with `agents.create()` — the session only takes `agent: { type: "agent", id: agent.id }`.

### Minimal

```typescript
// 1. Create the agent (reusable, versioned)
const agent = await client.beta.agents.create(
  {
    name: "Coding Assistant",
    model: "claude-opus-4-8",
    tools: [{ type: "agent_toolset_20260401", default_config: { enabled: true } }],
  },
);

// 2. Start a session
const session = await client.beta.sessions.create(
  {
    agent: { type: "agent", id: agent.id, version: agent.version },
    environment_id: environment.id,
  },
);
console.log(session.id, session.status);
```

### With system prompt and custom tools

```typescript
const agent = await client.beta.agents.create(
  {
    name: "Code Reviewer",
    model: "claude-opus-4-8",
    system: "You are a senior code reviewer.",
    tools: [
      { type: "agent_toolset_20260401", default_config: { enabled: true } },
      {
        type: "custom",
        name: "run_tests",
        description: "Run the test suite",
        input_schema: {
          type: "object",
          properties: {
            test_path: { type: "string", description: "Path to test file" },
          },
          required: ["test_path"],
        },
      },
    ],
  },
);

const session = await client.beta.sessions.create(
  {
    agent: { type: "agent", id: agent.id, version: agent.version },
    environment_id: environment.id,
    title: "Code review session",
    resources: [
      {
        type: "github_repository",
        url: "https://github.com/owner/repo",
        mount_path: "/workspace/repo",
        authorization_token: process.env.GITHUB_TOKEN,
        branch: "main",
      },
    ],
  },
);
```

---

## Send a User Message

```typescript
await client.beta.sessions.events.send(
  session.id,
  {
    events: [
      {
        type: "user.message",
        content: [{ type: "text", text: "Review the auth module" }],
      },
    ],
  },
);
```

> 💡 **Stream-first:** Open the stream *before* (or concurrently with) sending the message. The stream only delivers events that occur after it opens — stream-after-send means early events arrive buffered in one batch. See [Steering Patterns](../../shared/managed-agents-events.md#steering-patterns).

---

## Stream Events (SSE)

```typescript
// Stream-first: open stream and send concurrently
const [events] = await Promise.all([
  collectStream(session.id),
  client.beta.sessions.events.send(
    session.id,
    { events: [{ type: "user.message", content: [{ type: "text", text: "..." }] }] },
  ),
]);

// Standalone stream iteration:
const stream = await client.beta.sessions.events.stream(
  session.id,
);

for await (const event of stream) {
  switch (event.type) {
    case "agent.message":
      for (const block of event.content) {
        if (block.type === "text") {
          process.stdout.write(block.text);
        }
      }
      break;
    case "agent.custom_tool_use":
      // Custom tool invocation — session is now idle
      console.log(`\nCustom tool call: event.name`);
      console.log(`Input: JSON.stringify(event.input)`);
      break;
    case "session.status_idle":
      console.log("\n--- Agent idle ---");
      break;
    case "session.status_terminated":
      console.log("\n--- Session terminated ---");
      break;
  }
}
```

---

## Provide Custom Tool Result

```typescript
await client.beta.sessions.events.send(
  session.id,
  {
    events: [
      {
        type: "user.custom_tool_result",
        custom_tool_use_id: "sevt_abc123",
        content: [{ type: "text", text: "All 42 tests passed." }],
      },
    ],
  },
);
```

---

## Poll Events

```typescript
const events = await client.beta.sessions.events.list(
  session.id,
);
for (const event of events.data) {
  console.log(`event.type: event.id`);
}
```

---

## Full Streaming Loop with Custom Tools

```typescript
function runCustomTool(toolName: string, toolInput: unknown): string {
  if (toolName === "run_tests") {
    // Your tool implementation here
    return "All tests passed.";
  }
  return `Unknown tool: toolName`;
}

async function runSession(client: Anthropic, sessionId: string) {
  while (true) {
    const stream = await client.beta.sessions.events.stream(
      sessionId,
    );

    const toolCalls: Anthropic.Beta.Sessions.BetaManagedAgentsAgentCustomToolUseEvent[] = [];

    for await (const event of stream) {
      if (event.type === "agent.message") {
        for (const block of event.content) {
          if (block.type === "text") {
            process.stdout.write(block.text);
          }
        }
      } else if (event.type === "agent.custom_tool_use") {
        toolCalls.push(event);
      } else if (event.type === "session.status_idle") {
        break;
      } else if (event.type === "session.status_terminated") {
        return;
      }
    }

    if (toolCalls.length === 0) break;

    // Process custom tool calls
    const results = toolCalls.map((call) => ({
      type: "user.custom_tool_result" as const,
      custom_tool_use_id: call.id,
      content: [{ type: "text" as const, text: runCustomTool(call.name, call.input) }],
    }));

    await client.beta.sessions.events.send(
      sessionId,
      { events: results },
    );
  }
}
```

---

## Upload a File

```typescript
import fs from "fs";

const file = await client.beta.files.upload({
  file: fs.createReadStream("data.csv"),
});

// Use in a session
const session = await client.beta.sessions.create(
  {
    agent: { type: "agent", id: agent.id, version: agent.version },
    environment_id: environment.id,
    resources: [{ type: "file", file_id: file.id, mount_path: "/workspace/data.csv" }],
  },
);
```

---

## List and Download Session Files

List files the agent wrote to `/mnt/session/outputs/` during a session, then download them.

```typescript
import fs from "fs";

// List files associated with a session
const files = await client.beta.files.list({
  scope_id: session.id,
  betas: ["managed-agents-2026-04-01"],
});
for (const f of files.data) {
  console.log(f.filename, f.size_bytes);

  // Download and save to disk
  const resp = await client.beta.files.download(f.id);
  const buffer = Buffer.from(await resp.arrayBuffer());
  fs.writeFileSync(f.filename, buffer);
}
```

> 💡 There's a brief indexing lag (~1–3s) between `session.status_idle` and output files appearing in `files.list`. Retry once or twice if the list is empty.

---

## Session Management

```typescript
// Get session details
const session = await client.beta.sessions.retrieve("sesn_011CZxAbc123Def456");
console.log(session.status, session.usage);

// List sessions
const sessions = await client.beta.sessions.list();

// Delete a session
await client.beta.sessions.delete("sesn_011CZxAbc123Def456");

// Archive a session
await client.beta.sessions.archive("sesn_011CZxAbc123Def456");
```

---

## MCP Server Integration

```typescript
// Agent declares MCP server (no auth here — auth goes in a vault)
const agent = await client.beta.agents.create({
  name: "MCP Agent",
  model: "claude-opus-4-8",
  mcp_servers: [
    { type: "url", name: "my-tools", url: "https://my-mcp-server.example.com/sse" },
  ],
  tools: [
    { type: "agent_toolset_20260401", default_config: { enabled: true } },
    { type: "mcp_toolset", mcp_server_name: "my-tools" },
  ],
});

// Session attaches vault(s) containing credentials for those MCP server URLs
const session = await client.beta.sessions.create({
  agent: agent.id,
  environment_id: environment.id,
  vault_ids: [vault.id],
});
```

See `shared/managed-agents-tools.md` §Vaults for creating vaults and adding credentials.

FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/claude-api
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: canvas-design
description: Create beautiful visual art in .png and .pdf documents using design philosophy. You should use this skill when the user asks to create a poster, piece of art, design, or other static piece. Create original visual designs, never copying existing artists' work to avoid copyright violations.
license: Complete terms in LICENSE.txt
---

These are instructions for creating design philosophies - aesthetic movements that are then EXPRESSED VISUALLY. Output only .md files, .pdf files, and .png files.

Complete this in two steps:
1. Design Philosophy Creation (.md file)
2. Express by creating it on a canvas (.pdf file or .png file)

First, undertake this task:

## DESIGN PHILOSOPHY CREATION

To begin, create a VISUAL PHILOSOPHY (not layouts or templates) that will be interpreted through:
- Form, space, color, composition
- Images, graphics, shapes, patterns
- Minimal text as visual accent

### THE CRITICAL UNDERSTANDING
- What is received: Some subtle input or instructions by the user that should be taken into account, but used as a foundation; it should not constrain creative freedom.
- What is created: A design philosophy/aesthetic movement.
- What happens next: Then, the same version receives the philosophy and EXPRESSES IT VISUALLY - creating artifacts that are 90% visual design, 10% essential text.

Consider this approach:
- Write a manifesto for an art movement
- The next phase involves making the artwork

The philosophy must emphasize: Visual expression. Spatial communication. Artistic interpretation. Minimal words.

### HOW TO GENERATE A VISUAL PHILOSOPHY

**Name the movement** (1-2 words): "Brutalist Joy" / "Chromatic Silence" / "Metabolist Dreams"

**Articulate the philosophy** (4-6 paragraphs - concise but complete):

To capture the VISUAL essence, express how the philosophy manifests through:
- Space and form
- Color and material
- Scale and rhythm
- Composition and balance
- Visual hierarchy

**CRITICAL GUIDELINES:**
- **Avoid redundancy**: Each design aspect should be mentioned once. Avoid repeating points about color theory, spatial relationships, or typographic principles unless adding new depth.
- **Emphasize craftsmanship REPEATEDLY**: The philosophy MUST stress multiple times that the final work should appear as though it took countless hours to create, was labored over with care, and comes from someone at the absolute top of their field. This framing is essential - repeat phrases like "meticulously crafted," "the product of deep expertise," "painstaking attention," "master-level execution."
- **Leave creative space**: Remain specific about the aesthetic direction, but concise enough that the next Claude has room to make interpretive choices also at a extremely high level of craftmanship.

The philosophy must guide the next version to express ideas VISUALLY, not through text. Information lives in design, not paragraphs.

### PHILOSOPHY EXAMPLES

**"Concrete Poetry"**
Philosophy: Communication through monumental form and bold geometry.
Visual expression: Massive color blocks, sculptural typography (huge single words, tiny labels), Brutalist spatial divisions, Polish poster energy meets Le Corbusier. Ideas expressed through visual weight and spatial tension, not explanation. Text as rare, powerful gesture - never paragraphs, only essential words integrated into the visual architecture. Every element placed with the precision of a master craftsman.

**"Chromatic Language"**
Philosophy: Color as the primary information system.
Visual expression: Geometric precision where color zones create meaning. Typography minimal - small sans-serif labels letting chromatic fields communicate. Think Josef Albers' interaction meets data visualization. Information encoded spatially and chromatically. Words only to anchor what color already shows. The result of painstaking chromatic calibration.

**"Analog Meditation"**
Philosophy: Quiet visual contemplation through texture and breathing room.
Visual expression: Paper grain, ink bleeds, vast negative space. Photography and illustration dominate. Typography whispered (small, restrained, serving the visual). Japanese photobook aesthetic. Images breathe across pages. Text appears sparingly - short phrases, never explanatory blocks. Each composition balanced with the care of a meditation practice.

**"Organic Systems"**
Philosophy: Natural clustering and modular growth patterns.
Visual expression: Rounded forms, organic arrangements, color from nature through architecture. Information shown through visual diagrams, spatial relationships, iconography. Text only for key labels floating in space. The composition tells the story through expert spatial orchestration.

**"Geometric Silence"**
Philosophy: Pure order and restraint.
Visual expression: Grid-based precision, bold photography or stark graphics, dramatic negative space. Typography precise but minimal - small essential text, large quiet zones. Swiss formalism meets Brutalist material honesty. Structure communicates, not words. Every alignment the work of countless refinements.

*These are condensed examples. The actual design philosophy should be 4-6 substantial paragraphs.*

### ESSENTIAL PRINCIPLES
- **VISUAL PHILOSOPHY**: Create an aesthetic worldview to be expressed through design
- **MINIMAL TEXT**: Always emphasize that text is sparse, essential-only, integrated as visual element - never lengthy
- **SPATIAL EXPRESSION**: Ideas communicate through space, form, color, composition - not paragraphs
- **ARTISTIC FREEDOM**: The next Claude interprets the philosophy visually - provide creative room
- **PURE DESIGN**: This is about making ART OBJECTS, not documents with decoration
- **EXPERT CRAFTSMANSHIP**: Repeatedly emphasize the final work must look meticulously crafted, labored over with care, the product of countless hours by someone at the top of their field

**The design philosophy should be 4-6 paragraphs long.** Fill it with poetic design philosophy that brings together the core vision. Avoid repeating the same points. Keep the design philosophy generic without mentioning the intention of the art, as if it can be used wherever. Output the design philosophy as a .md file.

---

## DEDUCING THE SUBTLE REFERENCE

**CRITICAL STEP**: Before creating the canvas, identify the subtle conceptual thread from the original request.

**THE ESSENTIAL PRINCIPLE**:
The topic is a **subtle, niche reference embedded within the art itself** - not always literal, always sophisticated. Someone familiar with the subject should feel it intuitively, while others simply experience a masterful abstract composition. The design philosophy provides the aesthetic language. The deduced topic provides the soul - the quiet conceptual DNA woven invisibly into form, color, and composition.

This is **VERY IMPORTANT**: The reference must be refined so it enhances the work's depth without announcing itself. Think like a jazz musician quoting another song - only those who know will catch it, but everyone appreciates the music.

---

## CANVAS CREATION

With both the philosophy and the conceptual framework established, express it on a canvas. Take a moment to gather thoughts and clear the mind. Use the design philosophy created and the instructions below to craft a masterpiece, embodying all aspects of the philosophy with expert craftsmanship.

**IMPORTANT**: For any type of content, even if the user requests something for a movie/game/book, the approach should still be sophisticated. Never lose sight of the idea that this should be art, not something that's cartoony or amateur.

To create museum or magazine quality work, use the design philosophy as the foundation. Create one single page, highly visual, design-forward PDF or PNG output (unless asked for more pages). Generally use repeating patterns and perfect shapes. Treat the abstract philosophical design as if it were a scientific bible, borrowing the visual language of systematic observation—dense accumulation of marks, repeated elements, or layered patterns that build meaning through patient repetition and reward sustained viewing. Add sparse, clinical typography and systematic reference markers that suggest this could be a diagram from an imaginary discipline, treating the invisible subject with the same reverence typically reserved for documenting observable phenomena. Anchor the piece with simple phrase(s) or details positioned subtly, using a limited color palette that feels intentional and cohesive. Embrace the paradox of using analytical visual language to express ideas about human experience: the result should feel like an artifact that proves something ephemeral can be studied, mapped, and understood through careful attention. This is true art. 

**Text as a contextual element**: Text is always minimal and visual-first, but let context guide whether that means whisper-quiet labels or bold typographic gestures. A punk venue poster might have larger, more aggressive type than a minimalist ceramics studio identity. Most of the time, font should be thin. All use of fonts must be design-forward and prioritize visual communication. Regardless of text scale, nothing falls off the page and nothing overlaps. Every element must be contained within the canvas boundaries with proper margins. Check carefully that all text, graphics, and visual elements have breathing room and clear separation. This is non-negotiable for professional execution. **IMPORTANT: Use different fonts if writing text. Search the `./canvas-fonts` directory. Regardless of approach, sophistication is non-negotiable.**

Download and use whatever fonts are needed to make this a reality. Get creative by making the typography actually part of the art itself -- if the art is abstract, bring the font onto the canvas, not typeset digitally.

To push boundaries, follow design instinct/intuition while using the philosophy as a guiding principle. Embrace ultimate design freedom and choice. Push aesthetics and design to the frontier. 

**CRITICAL**: To achieve human-crafted quality (not AI-generated), create work that looks like it took countless hours. Make it appear as though someone at the absolute top of their field labored over every detail with painstaking care. Ensure the composition, spacing, color choices, typography - everything screams expert-level craftsmanship. Double-check that nothing overlaps, formatting is flawless, every detail perfect. Create something that could be shown to people to prove expertise and rank as undeniably impressive.

Output the final result as a single, downloadable .pdf or .png file, alongside the design philosophy used as a .md file.

---

## FINAL STEP

**IMPORTANT**: The user ALREADY said "It isn't perfect enough. It must be pristine, a masterpiece if craftsmanship, as if it were about to be displayed in a museum."

**CRITICAL**: To refine the work, avoid adding more graphics; instead refine what has been created and make it extremely crisp, respecting the design philosophy and the principles of minimalism entirely. Rather than adding a fun filter or refactoring a font, consider how to make the existing composition more cohesive with the art. If the instinct is to call a new function or draw a new shape, STOP and instead ask: "How can I make what's already here more of a piece of art?"

Take a second pass. Go back to the code and refine/polish further to make this a philosophically designed masterpiece.

## MULTI-PAGE OPTION

To create additional pages when requested, create more creative pages along the same lines as the design philosophy but distinctly different as well. Bundle those pages in the same .pdf or many .pngs. Treat the first page as just a single page in a whole coffee table book waiting to be filled. Make the next pages unique twists and memories of the original. Have them almost tell a story in a very tasteful way. Exercise full creative freedom.
FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:canvas-fonts/ArsenalSC-OFL.txt
Copyright 2012 The Arsenal Project Authors (andrij.design@gmail.com)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/ArsenalSC-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/BigShoulders-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/BigShoulders-OFL.txt
Copyright 2019 The Big Shoulders Project Authors (https://github.com/xotypeco/big_shoulders)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/BigShoulders-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Boldonse-OFL.txt
Copyright 2024 The Boldonse Project Authors (https://github.com/googlefonts/boldonse)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Boldonse-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/BricolageGrotesque-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/BricolageGrotesque-OFL.txt
Copyright 2022 The Bricolage Grotesque Project Authors (https://github.com/ateliertriay/bricolage)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/BricolageGrotesque-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/CrimsonPro-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/CrimsonPro-Italic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/CrimsonPro-OFL.txt
Copyright 2018 The Crimson Pro Project Authors (https://github.com/Fonthausen/CrimsonPro)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/CrimsonPro-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/DMMono-OFL.txt
Copyright 2020 The DM Mono Project Authors (https://www.github.com/googlefonts/dm-mono)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/DMMono-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/EricaOne-OFL.txt
Copyright (c) 2011 by LatinoType Limitada (luciano@latinotype.com), 
with Reserved Font Names "Erica One"

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/EricaOne-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/GeistMono-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/GeistMono-OFL.txt
Copyright 2024 The Geist Project Authors (https://github.com/vercel/geist-font.git)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/GeistMono-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Gloock-OFL.txt
Copyright 2022 The Gloock Project Authors (https://github.com/duartp/gloock)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Gloock-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/IBMPlexMono-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/IBMPlexMono-OFL.txt
Copyright © 2017 IBM Corp. with Reserved Font Name "Plex"

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/IBMPlexMono-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/IBMPlexSerif-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/IBMPlexSerif-BoldItalic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/IBMPlexSerif-Italic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/IBMPlexSerif-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/InstrumentSans-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/InstrumentSans-BoldItalic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/InstrumentSans-Italic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/InstrumentSans-OFL.txt
Copyright 2022 The Instrument Sans Project Authors (https://github.com/Instrument/instrument-sans)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/InstrumentSans-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/InstrumentSerif-Italic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/InstrumentSerif-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Italiana-OFL.txt
Copyright (c) 2011, Santiago Orozco (hi@typemade.mx), with Reserved Font Name "Italiana".

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Italiana-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/JetBrainsMono-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/JetBrainsMono-OFL.txt
Copyright 2020 The JetBrains Mono Project Authors (https://github.com/JetBrains/JetBrainsMono)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/JetBrainsMono-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Jura-Light.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Jura-Medium.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Jura-OFL.txt
Copyright 2019 The Jura Project Authors (https://github.com/ossobuffo/jura)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/LibreBaskerville-OFL.txt
Copyright 2012 The Libre Baskerville Project Authors (https://github.com/impallari/Libre-Baskerville) with Reserved Font Name Libre Baskerville.

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/LibreBaskerville-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Lora-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Lora-BoldItalic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Lora-Italic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Lora-OFL.txt
Copyright 2011 The Lora Project Authors (https://github.com/cyrealtype/Lora-Cyrillic), with Reserved Font Name "Lora".

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Lora-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/NationalPark-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/NationalPark-OFL.txt
Copyright 2025 The National Park Project Authors (https://github.com/benhoepner/National-Park)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/NationalPark-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/NothingYouCouldDo-OFL.txt
Copyright (c) 2010, Kimberly Geswein (kimberlygeswein.com)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/NothingYouCouldDo-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Outfit-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Outfit-OFL.txt
Copyright 2021 The Outfit Project Authors (https://github.com/Outfitio/Outfit-Fonts)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Outfit-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/PixelifySans-Medium.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/PixelifySans-OFL.txt
Copyright 2021 The Pixelify Sans Project Authors (https://github.com/eifetx/Pixelify-Sans)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/PoiretOne-OFL.txt
Copyright (c) 2011, Denis Masharov (denis.masharov@gmail.com)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/PoiretOne-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/RedHatMono-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/RedHatMono-OFL.txt
Copyright 2024 The Red Hat Project Authors (https://github.com/RedHatOfficial/RedHatFont)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/RedHatMono-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Silkscreen-OFL.txt
Copyright 2001 The Silkscreen Project Authors (https://github.com/googlefonts/silkscreen)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Silkscreen-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/SmoochSans-Medium.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/SmoochSans-OFL.txt
Copyright 2016 The Smooch Sans Project Authors (https://github.com/googlefonts/smooch-sans)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Tektur-Medium.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/Tektur-OFL.txt
Copyright 2023 The Tektur Project Authors (https://www.github.com/hyvyys/Tektur)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/Tektur-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/WorkSans-Bold.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/WorkSans-BoldItalic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/WorkSans-Italic.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/WorkSans-OFL.txt
Copyright 2019 The Work Sans Project Authors (https://github.com/weiweihuanghuang/Work-Sans)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/WorkSans-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:canvas-fonts/YoungSerif-OFL.txt
Copyright 2023 The Young Serif Project Authors (https://github.com/noirblancrouge/YoungSerif)

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
https://openfontlicense.org


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded, 
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.

FILE:canvas-fonts/YoungSerif-Regular.ttf
[Binary or non-UTF8 file skipped during import]
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/canvas-design
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: brand-guidelines
description: Applies Anthropic's official brand colors and typography to any sort of artifact that may benefit from having Anthropic's look-and-feel. Use it when brand colors or style guidelines, visual formatting, or company design standards apply.
license: Complete terms in LICENSE.txt
---

# Anthropic Brand Styling

## Overview

To access Anthropic's official brand identity and style resources, use this skill.

**Keywords**: branding, corporate identity, visual identity, post-processing, styling, brand colors, typography, Anthropic brand, visual formatting, visual design

## Brand Guidelines

### Colors

**Main Colors:**

- Dark: `#141413` - Primary text and dark backgrounds
- Light: `#faf9f5` - Light backgrounds and text on dark
- Mid Gray: `#b0aea5` - Secondary elements
- Light Gray: `#e8e6dc` - Subtle backgrounds

**Accent Colors:**

- Orange: `#d97757` - Primary accent
- Blue: `#6a9bcc` - Secondary accent
- Green: `#788c5d` - Tertiary accent

### Typography

- **Headings**: Poppins (with Arial fallback)
- **Body Text**: Lora (with Georgia fallback)
- **Note**: Fonts should be pre-installed in your environment for best results

## Features

### Smart Font Application

- Applies Poppins font to headings (24pt and larger)
- Applies Lora font to body text
- Automatically falls back to Arial/Georgia if custom fonts unavailable
- Preserves readability across all systems

### Text Styling

- Headings (24pt+): Poppins font
- Body text: Lora font
- Smart color selection based on background
- Preserves text hierarchy and formatting

### Shape and Accent Colors

- Non-text shapes use accent colors
- Cycles through orange, blue, and green accents
- Maintains visual interest while staying on-brand

## Technical Details

### Font Management

- Uses system-installed Poppins and Lora fonts when available
- Provides automatic fallback to Arial (headings) and Georgia (body)
- No font installation required - works with existing system fonts
- For best results, pre-install Poppins and Lora fonts in your environment

### Color Application

- Uses RGB color values for precise brand matching
- Applied via python-pptx's RGBColor class
- Maintains color fidelity across different systems

FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/brand-guidelines
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

---
name: algorithmic-art
description: Creating algorithmic art using p5.js with seeded randomness and interactive parameter exploration. Use this when users request creating art using code, generative art, algorithmic art, flow fields, or particle systems. Create original algorithmic art rather than copying existing artists' work to avoid copyright violations.
license: Complete terms in LICENSE.txt
---

Algorithmic philosophies are computational aesthetic movements that are then expressed through code. Output .md files (philosophy), .html files (interactive viewer), and .js files (generative algorithms).

This happens in two steps:
1. Algorithmic Philosophy Creation (.md file)
2. Express by creating p5.js generative art (.html + .js files)

First, undertake this task:

## ALGORITHMIC PHILOSOPHY CREATION

To begin, create an ALGORITHMIC PHILOSOPHY (not static images or templates) that will be interpreted through:
- Computational processes, emergent behavior, mathematical beauty
- Seeded randomness, noise fields, organic systems
- Particles, flows, fields, forces
- Parametric variation and controlled chaos

### THE CRITICAL UNDERSTANDING
- What is received: Some subtle input or instructions by the user to take into account, but use as a foundation; it should not constrain creative freedom.
- What is created: An algorithmic philosophy/generative aesthetic movement.
- What happens next: The same version receives the philosophy and EXPRESSES IT IN CODE - creating p5.js sketches that are 90% algorithmic generation, 10% essential parameters.

Consider this approach:
- Write a manifesto for a generative art movement
- The next phase involves writing the algorithm that brings it to life

The philosophy must emphasize: Algorithmic expression. Emergent behavior. Computational beauty. Seeded variation.

### HOW TO GENERATE AN ALGORITHMIC PHILOSOPHY

**Name the movement** (1-2 words): "Organic Turbulence" / "Quantum Harmonics" / "Emergent Stillness"

**Articulate the philosophy** (4-6 paragraphs - concise but complete):

To capture the ALGORITHMIC essence, express how this philosophy manifests through:
- Computational processes and mathematical relationships?
- Noise functions and randomness patterns?
- Particle behaviors and field dynamics?
- Temporal evolution and system states?
- Parametric variation and emergent complexity?

**CRITICAL GUIDELINES:**
- **Avoid redundancy**: Each algorithmic aspect should be mentioned once. Avoid repeating concepts about noise theory, particle dynamics, or mathematical principles unless adding new depth.
- **Emphasize craftsmanship REPEATEDLY**: The philosophy MUST stress multiple times that the final algorithm should appear as though it took countless hours to develop, was refined with care, and comes from someone at the absolute top of their field. This framing is essential - repeat phrases like "meticulously crafted algorithm," "the product of deep computational expertise," "painstaking optimization," "master-level implementation."
- **Leave creative space**: Be specific about the algorithmic direction, but concise enough that the next Claude has room to make interpretive implementation choices at an extremely high level of craftsmanship.

The philosophy must guide the next version to express ideas ALGORITHMICALLY, not through static images. Beauty lives in the process, not the final frame.

### PHILOSOPHY EXAMPLES

**"Organic Turbulence"**
Philosophy: Chaos constrained by natural law, order emerging from disorder.
Algorithmic expression: Flow fields driven by layered Perlin noise. Thousands of particles following vector forces, their trails accumulating into organic density maps. Multiple noise octaves create turbulent regions and calm zones. Color emerges from velocity and density - fast particles burn bright, slow ones fade to shadow. The algorithm runs until equilibrium - a meticulously tuned balance where every parameter was refined through countless iterations by a master of computational aesthetics.

**"Quantum Harmonics"**
Philosophy: Discrete entities exhibiting wave-like interference patterns.
Algorithmic expression: Particles initialized on a grid, each carrying a phase value that evolves through sine waves. When particles are near, their phases interfere - constructive interference creates bright nodes, destructive creates voids. Simple harmonic motion generates complex emergent mandalas. The result of painstaking frequency calibration where every ratio was carefully chosen to produce resonant beauty.

**"Recursive Whispers"**
Philosophy: Self-similarity across scales, infinite depth in finite space.
Algorithmic expression: Branching structures that subdivide recursively. Each branch slightly randomized but constrained by golden ratios. L-systems or recursive subdivision generate tree-like forms that feel both mathematical and organic. Subtle noise perturbations break perfect symmetry. Line weights diminish with each recursion level. Every branching angle the product of deep mathematical exploration.

**"Field Dynamics"**
Philosophy: Invisible forces made visible through their effects on matter.
Algorithmic expression: Vector fields constructed from mathematical functions or noise. Particles born at edges, flowing along field lines, dying when they reach equilibrium or boundaries. Multiple fields can attract, repel, or rotate particles. The visualization shows only the traces - ghost-like evidence of invisible forces. A computational dance meticulously choreographed through force balance.

**"Stochastic Crystallization"**
Philosophy: Random processes crystallizing into ordered structures.
Algorithmic expression: Randomized circle packing or Voronoi tessellation. Start with random points, let them evolve through relaxation algorithms. Cells push apart until equilibrium. Color based on cell size, neighbor count, or distance from center. The organic tiling that emerges feels both random and inevitable. Every seed produces unique crystalline beauty - the mark of a master-level generative algorithm.

*These are condensed examples. The actual algorithmic philosophy should be 4-6 substantial paragraphs.*

### ESSENTIAL PRINCIPLES
- **ALGORITHMIC PHILOSOPHY**: Creating a computational worldview to be expressed through code
- **PROCESS OVER PRODUCT**: Always emphasize that beauty emerges from the algorithm's execution - each run is unique
- **PARAMETRIC EXPRESSION**: Ideas communicate through mathematical relationships, forces, behaviors - not static composition
- **ARTISTIC FREEDOM**: The next Claude interprets the philosophy algorithmically - provide creative implementation room
- **PURE GENERATIVE ART**: This is about making LIVING ALGORITHMS, not static images with randomness
- **EXPERT CRAFTSMANSHIP**: Repeatedly emphasize the final algorithm must feel meticulously crafted, refined through countless iterations, the product of deep expertise by someone at the absolute top of their field in computational aesthetics

**The algorithmic philosophy should be 4-6 paragraphs long.** Fill it with poetic computational philosophy that brings together the intended vision. Avoid repeating the same points. Output this algorithmic philosophy as a .md file.

---

## DEDUCING THE CONCEPTUAL SEED

**CRITICAL STEP**: Before implementing the algorithm, identify the subtle conceptual thread from the original request.

**THE ESSENTIAL PRINCIPLE**:
The concept is a **subtle, niche reference embedded within the algorithm itself** - not always literal, always sophisticated. Someone familiar with the subject should feel it intuitively, while others simply experience a masterful generative composition. The algorithmic philosophy provides the computational language. The deduced concept provides the soul - the quiet conceptual DNA woven invisibly into parameters, behaviors, and emergence patterns.

This is **VERY IMPORTANT**: The reference must be so refined that it enhances the work's depth without announcing itself. Think like a jazz musician quoting another song through algorithmic harmony - only those who know will catch it, but everyone appreciates the generative beauty.

---

## P5.JS IMPLEMENTATION

With the philosophy AND conceptual framework established, express it through code. Pause to gather thoughts before proceeding. Use only the algorithmic philosophy created and the instructions below.

### ⚠️ STEP 0: READ THE TEMPLATE FIRST ⚠️

**CRITICAL: BEFORE writing any HTML:**

1. **Read** `templates/viewer.html` using the Read tool
2. **Study** the exact structure, styling, and Anthropic branding
3. **Use that file as the LITERAL STARTING POINT** - not just inspiration
4. **Keep all FIXED sections exactly as shown** (header, sidebar structure, Anthropic colors/fonts, seed controls, action buttons)
5. **Replace only the VARIABLE sections** marked in the file's comments (algorithm, parameters, UI controls for parameters)

**Avoid:**
- ❌ Creating HTML from scratch
- ❌ Inventing custom styling or color schemes
- ❌ Using system fonts or dark themes
- ❌ Changing the sidebar structure

**Follow these practices:**
- ✅ Copy the template's exact HTML structure
- ✅ Keep Anthropic branding (Poppins/Lora fonts, light colors, gradient backdrop)
- ✅ Maintain the sidebar layout (Seed → Parameters → Colors? → Actions)
- ✅ Replace only the p5.js algorithm and parameter controls

The template is the foundation. Build on it, don't rebuild it.

---

To create gallery-quality computational art that lives and breathes, use the algorithmic philosophy as the foundation.

### TECHNICAL REQUIREMENTS

**Seeded Randomness (Art Blocks Pattern)**:
```javascript
// ALWAYS use a seed for reproducibility
let seed = 12345; // or hash from user input
randomSeed(seed);
noiseSeed(seed);
```

**Parameter Structure - FOLLOW THE PHILOSOPHY**:

To establish parameters that emerge naturally from the algorithmic philosophy, consider: "What qualities of this system can be adjusted?"

```javascript
let params = {
  seed: 12345,  // Always include seed for reproducibility
  // colors
  // Add parameters that control YOUR algorithm:
  // - Quantities (how many?)
  // - Scales (how big? how fast?)
  // - Probabilities (how likely?)
  // - Ratios (what proportions?)
  // - Angles (what direction?)
  // - Thresholds (when does behavior change?)
};
```

**To design effective parameters, focus on the properties the system needs to be tunable rather than thinking in terms of "pattern types".**

**Core Algorithm - EXPRESS THE PHILOSOPHY**:

**CRITICAL**: The algorithmic philosophy should dictate what to build.

To express the philosophy through code, avoid thinking "which pattern should I use?" and instead think "how to express this philosophy through code?"

If the philosophy is about **organic emergence**, consider using:
- Elements that accumulate or grow over time
- Random processes constrained by natural rules
- Feedback loops and interactions

If the philosophy is about **mathematical beauty**, consider using:
- Geometric relationships and ratios
- Trigonometric functions and harmonics
- Precise calculations creating unexpected patterns

If the philosophy is about **controlled chaos**, consider using:
- Random variation within strict boundaries
- Bifurcation and phase transitions
- Order emerging from disorder

**The algorithm flows from the philosophy, not from a menu of options.**

To guide the implementation, let the conceptual essence inform creative and original choices. Build something that expresses the vision for this particular request.

**Canvas Setup**: Standard p5.js structure:
```javascript
function setup() {
  createCanvas(1200, 1200);
  // Initialize your system
}

function draw() {
  // Your generative algorithm
  // Can be static (noLoop) or animated
}
```

### CRAFTSMANSHIP REQUIREMENTS

**CRITICAL**: To achieve mastery, create algorithms that feel like they emerged through countless iterations by a master generative artist. Tune every parameter carefully. Ensure every pattern emerges with purpose. This is NOT random noise - this is CONTROLLED CHAOS refined through deep expertise.

- **Balance**: Complexity without visual noise, order without rigidity
- **Color Harmony**: Thoughtful palettes, not random RGB values
- **Composition**: Even in randomness, maintain visual hierarchy and flow
- **Performance**: Smooth execution, optimized for real-time if animated
- **Reproducibility**: Same seed ALWAYS produces identical output

### OUTPUT FORMAT

Output:
1. **Algorithmic Philosophy** - As markdown or text explaining the generative aesthetic
2. **Single HTML Artifact** - Self-contained interactive generative art built from `templates/viewer.html` (see STEP 0 and next section)

The HTML artifact contains everything: p5.js (from CDN), the algorithm, parameter controls, and UI - all in one file that works immediately in claude.ai artifacts or any browser. Start from the template file, not from scratch.

---

## INTERACTIVE ARTIFACT CREATION

**REMINDER: `templates/viewer.html` should have already been read (see STEP 0). Use that file as the starting point.**

To allow exploration of the generative art, create a single, self-contained HTML artifact. Ensure this artifact works immediately in claude.ai or any browser - no setup required. Embed everything inline.

### CRITICAL: WHAT'S FIXED VS VARIABLE

The `templates/viewer.html` file is the foundation. It contains the exact structure and styling needed.

**FIXED (always include exactly as shown):**
- Layout structure (header, sidebar, main canvas area)
- Anthropic branding (UI colors, fonts, gradients)
- Seed section in sidebar:
  - Seed display
  - Previous/Next buttons
  - Random button
  - Jump to seed input + Go button
- Actions section in sidebar:
  - Regenerate button
  - Reset button

**VARIABLE (customize for each artwork):**
- The entire p5.js algorithm (setup/draw/classes)
- The parameters object (define what the art needs)
- The Parameters section in sidebar:
  - Number of parameter controls
  - Parameter names
  - Min/max/step values for sliders
  - Control types (sliders, inputs, etc.)
- Colors section (optional):
  - Some art needs color pickers
  - Some art might use fixed colors
  - Some art might be monochrome (no color controls needed)
  - Decide based on the art's needs

**Every artwork should have unique parameters and algorithm!** The fixed parts provide consistent UX - everything else expresses the unique vision.

### REQUIRED FEATURES

**1. Parameter Controls**
- Sliders for numeric parameters (particle count, noise scale, speed, etc.)
- Color pickers for palette colors
- Real-time updates when parameters change
- Reset button to restore defaults

**2. Seed Navigation**
- Display current seed number
- "Previous" and "Next" buttons to cycle through seeds
- "Random" button for random seed
- Input field to jump to specific seed
- Generate 100 variations when requested (seeds 1-100)

**3. Single Artifact Structure**
```html
<!DOCTYPE html>
<html>
<head>
  <!-- p5.js from CDN - always available -->
  <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.7.0/p5.min.js"></script>
  <style>
    /* All styling inline - clean, minimal */
    /* Canvas on top, controls below */
  </style>
</head>
<body>
  <div id="canvas-container"></div>
  <div id="controls">
    <!-- All parameter controls -->
  </div>
  <script>
    // ALL p5.js code inline here
    // Parameter objects, classes, functions
    // setup() and draw()
    // UI handlers
    // Everything self-contained
  </script>
</body>
</html>
```

**CRITICAL**: This is a single artifact. No external files, no imports (except p5.js CDN). Everything inline.

**4. Implementation Details - BUILD THE SIDEBAR**

The sidebar structure:

**1. Seed (FIXED)** - Always include exactly as shown:
- Seed display
- Prev/Next/Random/Jump buttons

**2. Parameters (VARIABLE)** - Create controls for the art:
```html
<div class="control-group">
    <label>Parameter Name</label>
    <input type="range" id="param" min="..." max="..." step="..." value="..." oninput="updateParam('param', this.value)">
    <span class="value-display" id="param-value">...</span>
</div>
```
Add as many control-group divs as there are parameters.

**3. Colors (OPTIONAL/VARIABLE)** - Include if the art needs adjustable colors:
- Add color pickers if users should control palette
- Skip this section if the art uses fixed colors
- Skip if the art is monochrome

**4. Actions (FIXED)** - Always include exactly as shown:
- Regenerate button
- Reset button
- Download PNG button

**Requirements**:
- Seed controls must work (prev/next/random/jump/display)
- All parameters must have UI controls
- Regenerate, Reset, Download buttons must work
- Keep Anthropic branding (UI styling, not art colors)

### USING THE ARTIFACT

The HTML artifact works immediately:
1. **In claude.ai**: Displayed as an interactive artifact - runs instantly
2. **As a file**: Save and open in any browser - no server needed
3. **Sharing**: Send the HTML file - it's completely self-contained

---

## VARIATIONS & EXPLORATION

The artifact includes seed navigation by default (prev/next/random buttons), allowing users to explore variations without creating multiple files. If the user wants specific variations highlighted:

- Include seed presets (buttons for "Variation 1: Seed 42", "Variation 2: Seed 127", etc.)
- Add a "Gallery Mode" that shows thumbnails of multiple seeds side-by-side
- All within the same single artifact

This is like creating a series of prints from the same plate - the algorithm is consistent, but each seed reveals different facets of its potential. The interactive nature means users discover their own favorites by exploring the seed space.

---

## THE CREATIVE PROCESS

**User request** → **Algorithmic philosophy** → **Implementation**

Each request is unique. The process involves:

1. **Interpret the user's intent** - What aesthetic is being sought?
2. **Create an algorithmic philosophy** (4-6 paragraphs) describing the computational approach
3. **Implement it in code** - Build the algorithm that expresses this philosophy
4. **Design appropriate parameters** - What should be tunable?
5. **Build matching UI controls** - Sliders/inputs for those parameters

**The constants**:
- Anthropic branding (colors, fonts, layout)
- Seed navigation (always present)
- Self-contained HTML artifact

**Everything else is variable**:
- The algorithm itself
- The parameters
- The UI controls
- The visual outcome

To achieve the best results, trust creativity and let the philosophy guide the implementation.

---

## RESOURCES

This skill includes helpful templates and documentation:

- **templates/viewer.html**: REQUIRED STARTING POINT for all HTML artifacts.
  - This is the foundation - contains the exact structure and Anthropic branding
  - **Keep unchanged**: Layout structure, sidebar organization, Anthropic colors/fonts, seed controls, action buttons
  - **Replace**: The p5.js algorithm, parameter definitions, and UI controls in Parameters section
  - The extensive comments in the file mark exactly what to keep vs replace

- **templates/generator_template.js**: Reference for p5.js best practices and code structure principles.
  - Shows how to organize parameters, use seeded randomness, structure classes
  - NOT a pattern menu - use these principles to build unique algorithms
  - Embed algorithms inline in the HTML artifact (don't create separate .js files)

**Critical reminder**:
- The **template is the STARTING POINT**, not inspiration
- The **algorithm is where to create** something unique
- Don't copy the flow field example - build what the philosophy demands
- But DO keep the exact UI structure and Anthropic branding from the template
FILE:LICENSE.txt

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Anthropic, PBC.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
FILE:templates/generator_template.js
/**
 * ═══════════════════════════════════════════════════════════════════════════
 *                  P5.JS GENERATIVE ART - BEST PRACTICES
 * ═══════════════════════════════════════════════════════════════════════════
 *
 * This file shows STRUCTURE and PRINCIPLES for p5.js generative art.
 * It does NOT prescribe what art you should create.
 *
 * Your algorithmic philosophy should guide what you build.
 * These are just best practices for how to structure your code.
 *
 * ═══════════════════════════════════════════════════════════════════════════
 */

// ============================================================================
// 1. PARAMETER ORGANIZATION
// ============================================================================
// Keep all tunable parameters in one object
// This makes it easy to:
// - Connect to UI controls
// - Reset to defaults
// - Serialize/save configurations

let params = {
    // Define parameters that match YOUR algorithm
    // Examples (customize for your art):
    // - Counts: how many elements (particles, circles, branches, etc.)
    // - Scales: size, speed, spacing
    // - Probabilities: likelihood of events
    // - Angles: rotation, direction
    // - Colors: palette arrays

    seed: 12345,
    // define colorPalette as an array -- choose whatever colors you'd like ['#d97757', '#6a9bcc', '#788c5d', '#b0aea5']
    // Add YOUR parameters here based on your algorithm
};

// ============================================================================
// 2. SEEDED RANDOMNESS (Critical for reproducibility)
// ============================================================================
// ALWAYS use seeded random for Art Blocks-style reproducible output

function initializeSeed(seed) {
    randomSeed(seed);
    noiseSeed(seed);
    // Now all random() and noise() calls will be deterministic
}

// ============================================================================
// 3. P5.JS LIFECYCLE
// ============================================================================

function setup() {
    createCanvas(800, 800);

    // Initialize seed first
    initializeSeed(params.seed);

    // Set up your generative system
    // This is where you initialize:
    // - Arrays of objects
    // - Grid structures
    // - Initial positions
    // - Starting states

    // For static art: call noLoop() at the end of setup
    // For animated art: let draw() keep running
}

function draw() {
    // Option 1: Static generation (runs once, then stops)
    // - Generate everything in setup()
    // - Call noLoop() in setup()
    // - draw() doesn't do much or can be empty

    // Option 2: Animated generation (continuous)
    // - Update your system each frame
    // - Common patterns: particle movement, growth, evolution
    // - Can optionally call noLoop() after N frames

    // Option 3: User-triggered regeneration
    // - Use noLoop() by default
    // - Call redraw() when parameters change
}

// ============================================================================
// 4. CLASS STRUCTURE (When you need objects)
// ============================================================================
// Use classes when your algorithm involves multiple entities
// Examples: particles, agents, cells, nodes, etc.

class Entity {
    constructor() {
        // Initialize entity properties
        // Use random() here - it will be seeded
    }

    update() {
        // Update entity state
        // This might involve:
        // - Physics calculations
        // - Behavioral rules
        // - Interactions with neighbors
    }

    display() {
        // Render the entity
        // Keep rendering logic separate from update logic
    }
}

// ============================================================================
// 5. PERFORMANCE CONSIDERATIONS
// ============================================================================

// For large numbers of elements:
// - Pre-calculate what you can
// - Use simple collision detection (spatial hashing if needed)
// - Limit expensive operations (sqrt, trig) when possible
// - Consider using p5 vectors efficiently

// For smooth animation:
// - Aim for 60fps
// - Profile if things are slow
// - Consider reducing particle counts or simplifying calculations

// ============================================================================
// 6. UTILITY FUNCTIONS
// ============================================================================

// Color utilities
function hexToRgb(hex) {
    const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
    return result ? {
        r: parseInt(result[1], 16),
        g: parseInt(result[2], 16),
        b: parseInt(result[3], 16)
    } : null;
}

function colorFromPalette(index) {
    return params.colorPalette[index % params.colorPalette.length];
}

// Mapping and easing
function mapRange(value, inMin, inMax, outMin, outMax) {
    return outMin + (outMax - outMin) * ((value - inMin) / (inMax - inMin));
}

function easeInOutCubic(t) {
    return t < 0.5 ? 4 * t * t * t : 1 - Math.pow(-2 * t + 2, 3) / 2;
}

// Constrain to bounds
function wrapAround(value, max) {
    if (value < 0) return max;
    if (value > max) return 0;
    return value;
}

// ============================================================================
// 7. PARAMETER UPDATES (Connect to UI)
// ============================================================================

function updateParameter(paramName, value) {
    params[paramName] = value;
    // Decide if you need to regenerate or just update
    // Some params can update in real-time, others need full regeneration
}

function regenerate() {
    // Reinitialize your generative system
    // Useful when parameters change significantly
    initializeSeed(params.seed);
    // Then regenerate your system
}

// ============================================================================
// 8. COMMON P5.JS PATTERNS
// ============================================================================

// Drawing with transparency for trails/fading
function fadeBackground(opacity) {
    fill(250, 249, 245, opacity); // Anthropic light with alpha
    noStroke();
    rect(0, 0, width, height);
}

// Using noise for organic variation
function getNoiseValue(x, y, scale = 0.01) {
    return noise(x * scale, y * scale);
}

// Creating vectors from angles
function vectorFromAngle(angle, magnitude = 1) {
    return createVector(cos(angle), sin(angle)).mult(magnitude);
}

// ============================================================================
// 9. EXPORT FUNCTIONS
// ============================================================================

function exportImage() {
    saveCanvas('generative-art-' + params.seed, 'png');
}

// ============================================================================
// REMEMBER
// ============================================================================
//
// These are TOOLS and PRINCIPLES, not a recipe.
// Your algorithmic philosophy should guide WHAT you create.
// This structure helps you create it WELL.
//
// Focus on:
// - Clean, readable code
// - Parameterized for exploration
// - Seeded for reproducibility
// - Performant execution
//
// The art itself is entirely up to you!
//
// ============================================================================
FILE:templates/viewer.html
<!DOCTYPE html>
<!--
    THIS IS A TEMPLATE THAT SHOULD BE USED EVERY TIME AND MODIFIED.
    WHAT TO KEEP:
    ✓ Overall structure (header, sidebar, main content)
    ✓ Anthropic branding (colors, fonts, layout)
    ✓ Seed navigation section (always include this)
    ✓ Self-contained artifact (everything inline)

    WHAT TO CREATIVELY EDIT:
    ✗ The p5.js algorithm (implement YOUR vision)
    ✗ The parameters (define what YOUR art needs)
    ✗ The UI controls (match YOUR parameters)

    Let your philosophy guide the implementation.
    The world is your oyster - be creative!
-->
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Generative Art Viewer</title>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.7.0/p5.min.js"></script>
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600&family=Lora:wght@400;500&display=swap" rel="stylesheet">
    <style>
        /* Anthropic Brand Colors */
        :root {
            --anthropic-dark: #141413;
            --anthropic-light: #faf9f5;
            --anthropic-mid-gray: #b0aea5;
            --anthropic-light-gray: #e8e6dc;
            --anthropic-orange: #d97757;
            --anthropic-blue: #6a9bcc;
            --anthropic-green: #788c5d;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Poppins', sans-serif;
            background: linear-gradient(135deg, var(--anthropic-light) 0%, #f5f3ee 100%);
            min-height: 100vh;
            color: var(--anthropic-dark);
        }

        .container {
            display: flex;
            min-height: 100vh;
            padding: 20px;
            gap: 20px;
        }

        /* Sidebar */
        .sidebar {
            width: 320px;
            flex-shrink: 0;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            padding: 24px;
            border-radius: 12px;
            box-shadow: 0 10px 30px rgba(20, 20, 19, 0.1);
            overflow-y: auto;
            overflow-x: hidden;
        }

        .sidebar h1 {
            font-family: 'Lora', serif;
            font-size: 24px;
            font-weight: 500;
            color: var(--anthropic-dark);
            margin-bottom: 8px;
        }

        .sidebar .subtitle {
            color: var(--anthropic-mid-gray);
            font-size: 14px;
            margin-bottom: 32px;
            line-height: 1.4;
        }

        /* Control Sections */
        .control-section {
            margin-bottom: 32px;
        }

        .control-section h3 {
            font-size: 16px;
            font-weight: 600;
            color: var(--anthropic-dark);
            margin-bottom: 16px;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .control-section h3::before {
            content: '•';
            color: var(--anthropic-orange);
            font-weight: bold;
        }

        /* Seed Controls */
        .seed-input {
            width: 100%;
            background: var(--anthropic-light);
            padding: 12px;
            border-radius: 8px;
            font-family: 'Courier New', monospace;
            font-size: 14px;
            margin-bottom: 12px;
            border: 1px solid var(--anthropic-light-gray);
            text-align: center;
        }

        .seed-input:focus {
            outline: none;
            border-color: var(--anthropic-orange);
            box-shadow: 0 0 0 2px rgba(217, 119, 87, 0.1);
            background: white;
        }

        .seed-controls {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 8px;
            margin-bottom: 8px;
        }

        .regen-button {
            margin-bottom: 0;
        }

        /* Parameter Controls */
        .control-group {
            margin-bottom: 20px;
        }

        .control-group label {
            display: block;
            font-size: 14px;
            font-weight: 500;
            color: var(--anthropic-dark);
            margin-bottom: 8px;
        }

        .slider-container {
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .slider-container input[type="range"] {
            flex: 1;
            height: 4px;
            background: var(--anthropic-light-gray);
            border-radius: 2px;
            outline: none;
            -webkit-appearance: none;
        }

        .slider-container input[type="range"]::-webkit-slider-thumb {
            -webkit-appearance: none;
            width: 16px;
            height: 16px;
            background: var(--anthropic-orange);
            border-radius: 50%;
            cursor: pointer;
            transition: all 0.2s ease;
        }

        .slider-container input[type="range"]::-webkit-slider-thumb:hover {
            transform: scale(1.1);
            background: #c86641;
        }

        .slider-container input[type="range"]::-moz-range-thumb {
            width: 16px;
            height: 16px;
            background: var(--anthropic-orange);
            border-radius: 50%;
            border: none;
            cursor: pointer;
            transition: all 0.2s ease;
        }

        .value-display {
            font-family: 'Courier New', monospace;
            font-size: 12px;
            color: var(--anthropic-mid-gray);
            min-width: 60px;
            text-align: right;
        }

        /* Color Pickers */
        .color-group {
            margin-bottom: 16px;
        }

        .color-group label {
            display: block;
            font-size: 12px;
            color: var(--anthropic-mid-gray);
            margin-bottom: 4px;
        }

        .color-picker-container {
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .color-picker-container input[type="color"] {
            width: 32px;
            height: 32px;
            border: none;
            border-radius: 6px;
            cursor: pointer;
            background: none;
            padding: 0;
        }

        .color-value {
            font-family: 'Courier New', monospace;
            font-size: 12px;
            color: var(--anthropic-mid-gray);
        }

        /* Buttons */
        .button {
            background: var(--anthropic-orange);
            color: white;
            border: none;
            padding: 10px 16px;
            border-radius: 6px;
            font-size: 14px;
            font-weight: 500;
            cursor: pointer;
            transition: all 0.2s ease;
            width: 100%;
        }

        .button:hover {
            background: #c86641;
            transform: translateY(-1px);
        }

        .button:active {
            transform: translateY(0);
        }

        .button.secondary {
            background: var(--anthropic-blue);
        }

        .button.secondary:hover {
            background: #5a8bb8;
        }

        .button.tertiary {
            background: var(--anthropic-green);
        }

        .button.tertiary:hover {
            background: #6b7b52;
        }

        .button-row {
            display: flex;
            gap: 8px;
        }

        .button-row .button {
            flex: 1;
        }

        /* Canvas Area */
        .canvas-area {
            flex: 1;
            display: flex;
            align-items: center;
            justify-content: center;
            min-width: 0;
        }

        #canvas-container {
            width: 100%;
            max-width: 1000px;
            border-radius: 12px;
            overflow: hidden;
            box-shadow: 0 20px 40px rgba(20, 20, 19, 0.1);
            background: white;
        }

        #canvas-container canvas {
            display: block;
            width: 100% !important;
            height: auto !important;
        }

        /* Loading State */
        .loading {
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 18px;
            color: var(--anthropic-mid-gray);
        }

        /* Responsive - Stack on mobile */
        @media (max-width: 600px) {
            .container {
                flex-direction: column;
            }

            .sidebar {
                width: 100%;
            }

            .canvas-area {
                padding: 20px;
            }
        }
    </style>
</head>
<body>
    <div class="container">
        <!-- Control Sidebar -->
        <div class="sidebar">
            <!-- Headers (CUSTOMIZE THIS FOR YOUR ART) -->
            <h1>TITLE - EDIT</h1>
            <div class="subtitle">SUBHEADER - EDIT</div>

            <!-- Seed Section (ALWAYS KEEP THIS) -->
            <div class="control-section">
                <h3>Seed</h3>
                <input type="number" id="seed-input" class="seed-input" value="12345" onchange="updateSeed()">
                <div class="seed-controls">
                    <button class="button secondary" onclick="previousSeed()">← Prev</button>
                    <button class="button secondary" onclick="nextSeed()">Next →</button>
                </div>
                <button class="button tertiary regen-button" onclick="randomSeedAndUpdate()">↻ Random</button>
            </div>

            <!-- Parameters Section (CUSTOMIZE THIS FOR YOUR ART) -->
            <div class="control-section">
                <h3>Parameters</h3>
                
                <!-- Particle Count -->
                <div class="control-group">
                    <label>Particle Count</label>
                    <div class="slider-container">
                        <input type="range" id="particleCount" min="1000" max="10000" step="500" value="5000" oninput="updateParam('particleCount', this.value)">
                        <span class="value-display" id="particleCount-value">5000</span>
                    </div>
                </div>

                <!-- Flow Speed -->
                <div class="control-group">
                    <label>Flow Speed</label>
                    <div class="slider-container">
                        <input type="range" id="flowSpeed" min="0.1" max="2.0" step="0.1" value="0.5" oninput="updateParam('flowSpeed', this.value)">
                        <span class="value-display" id="flowSpeed-value">0.5</span>
                    </div>
                </div>

                <!-- Noise Scale -->
                <div class="control-group">
                    <label>Noise Scale</label>
                    <div class="slider-container">
                        <input type="range" id="noiseScale" min="0.001" max="0.02" step="0.001" value="0.005" oninput="updateParam('noiseScale', this.value)">
                        <span class="value-display" id="noiseScale-value">0.005</span>
                    </div>
                </div>

                <!-- Trail Length -->
                <div class="control-group">
                    <label>Trail Length</label>
                    <div class="slider-container">
                        <input type="range" id="trailLength" min="2" max="20" step="1" value="8" oninput="updateParam('trailLength', this.value)">
                        <span class="value-display" id="trailLength-value">8</span>
                    </div>
                </div>
            </div>

            <!-- Colors Section (OPTIONAL - CUSTOMIZE OR REMOVE) -->
            <div class="control-section">
                <h3>Colors</h3>
                
                <!-- Color 1 -->
                <div class="color-group">
                    <label>Primary Color</label>
                    <div class="color-picker-container">
                        <input type="color" id="color1" value="#d97757" onchange="updateColor('color1', this.value)">
                        <span class="color-value" id="color1-value">#d97757</span>
                    </div>
                </div>

                <!-- Color 2 -->
                <div class="color-group">
                    <label>Secondary Color</label>
                    <div class="color-picker-container">
                        <input type="color" id="color2" value="#6a9bcc" onchange="updateColor('color2', this.value)">
                        <span class="color-value" id="color2-value">#6a9bcc</span>
                    </div>
                </div>

                <!-- Color 3 -->
                <div class="color-group">
                    <label>Accent Color</label>
                    <div class="color-picker-container">
                        <input type="color" id="color3" value="#788c5d" onchange="updateColor('color3', this.value)">
                        <span class="color-value" id="color3-value">#788c5d</span>
                    </div>
                </div>
            </div>

            <!-- Actions Section (ALWAYS KEEP THIS) -->
            <div class="control-section">
                <h3>Actions</h3>
                <div class="button-row">
                    <button class="button" onclick="resetParameters()">Reset</button>
                </div>
            </div>
        </div>

        <!-- Main Canvas Area -->
        <div class="canvas-area">
            <div id="canvas-container">
                <div class="loading">Initializing generative art...</div>
            </div>
        </div>
    </div>

    <script>
        // ═══════════════════════════════════════════════════════════════════════
        // GENERATIVE ART PARAMETERS - CUSTOMIZE FOR YOUR ALGORITHM
        // ═══════════════════════════════════════════════════════════════════════

        let params = {
            seed: 12345,
            particleCount: 5000,
            flowSpeed: 0.5,
            noiseScale: 0.005,
            trailLength: 8,
            colorPalette: ['#d97757', '#6a9bcc', '#788c5d']
        };

        let defaultParams = {...params}; // Store defaults for reset

        // ═══════════════════════════════════════════════════════════════════════
        // P5.JS GENERATIVE ART ALGORITHM - REPLACE WITH YOUR VISION
        // ═══════════════════════════════════════════════════════════════════════

        let particles = [];
        let flowField = [];
        let cols, rows;
        let scl = 10; // Flow field resolution

        function setup() {
            let canvas = createCanvas(1200, 1200);
            canvas.parent('canvas-container');
            
            initializeSystem();
            
            // Remove loading message
            document.querySelector('.loading').style.display = 'none';
        }

        function initializeSystem() {
            // Seed the randomness for reproducibility
            randomSeed(params.seed);
            noiseSeed(params.seed);

            // Clear particles and recreate
            particles = [];
            
            // Initialize particles
            for (let i = 0; i < params.particleCount; i++) {
                particles.push(new Particle());
            }

            // Calculate flow field dimensions
            cols = floor(width / scl);
            rows = floor(height / scl);
            
            // Generate flow field
            generateFlowField();

            // Clear background
            background(250, 249, 245); // Anthropic light background
        }

        function generateFlowField() {
          // fill this in
        }

        function draw() {
            // fill this in
        }

        // ═══════════════════════════════════════════════════════════════════════
        // PARTICLE SYSTEM - CUSTOMIZE FOR YOUR ALGORITHM
        // ═══════════════════════════════════════════════════════════════════════

        class Particle {
            constructor() {
                // fill this in
            }
            // fill this in
        }

        // ═══════════════════════════════════════════════════════════════════════
        // UI CONTROL HANDLERS - CUSTOMIZE FOR YOUR PARAMETERS
        // ═══════════════════════════════════════════════════════════════════════

        function updateParam(paramName, value) {
            // fill this in
        }

        function updateColor(colorId, value) {
            // fill this in
        }

        // ═══════════════════════════════════════════════════════════════════════
        // SEED CONTROL FUNCTIONS - ALWAYS KEEP THESE
        // ═══════════════════════════════════════════════════════════════════════

        function updateSeedDisplay() {
            document.getElementById('seed-input').value = params.seed;
        }

        function updateSeed() {
            let input = document.getElementById('seed-input');
            let newSeed = parseInt(input.value);
            if (newSeed && newSeed > 0) {
                params.seed = newSeed;
                initializeSystem();
            } else {
                // Reset to current seed if invalid
                updateSeedDisplay();
            }
        }

        function previousSeed() {
            params.seed = Math.max(1, params.seed - 1);
            updateSeedDisplay();
            initializeSystem();
        }

        function nextSeed() {
            params.seed = params.seed + 1;
            updateSeedDisplay();
            initializeSystem();
        }

        function randomSeedAndUpdate() {
            params.seed = Math.floor(Math.random() * 999999) + 1;
            updateSeedDisplay();
            initializeSystem();
        }

        function resetParameters() {
            params = {...defaultParams};
            
            // Update UI elements
            document.getElementById('particleCount').value = params.particleCount;
            document.getElementById('particleCount-value').textContent = params.particleCount;
            document.getElementById('flowSpeed').value = params.flowSpeed;
            document.getElementById('flowSpeed-value').textContent = params.flowSpeed;
            document.getElementById('noiseScale').value = params.noiseScale;
            document.getElementById('noiseScale-value').textContent = params.noiseScale;
            document.getElementById('trailLength').value = params.trailLength;
            document.getElementById('trailLength-value').textContent = params.trailLength;
            
            // Reset colors
            document.getElementById('color1').value = params.colorPalette[0];
            document.getElementById('color1-value').textContent = params.colorPalette[0];
            document.getElementById('color2').value = params.colorPalette[1];
            document.getElementById('color2-value').textContent = params.colorPalette[1];
            document.getElementById('color3').value = params.colorPalette[2];
            document.getElementById('color3-value').textContent = params.colorPalette[2];
            
            updateSeedDisplay();
            initializeSystem();
        }

        // Initialize UI on load
        window.addEventListener('load', function() {
            updateSeedDisplay();
        });
    </script>
</body>
</html>
FILE:_SOURCE_LICENSE.md
Source: https://github.com/anthropics/skills/tree/main/skills/algorithmic-art
License: Apache-2.0
Commercial use: Yes, subject to the license terms and notices.
Imported: 2026-06-19T23:43:14.070Z

Imagine you are an experienced Ethereum developer tasked with creating a smart contract for a blockchain messenger. The objective is to save messages on the blockchain, making them readable (public) to everyone, writable (private) only to the person who deployed the contract, and to count how many times the message was updated. Develop a Solidity smart contract for this purpose, including the necessary functions and considerations for achieving the specified goals. Please provide the code and any relevant explanations to ensure a clear understanding of the implementation.

I want you to act as a linux terminal. I will type commands and you will reply with what the terminal should show. I want you to only reply with the terminal output inside one unique code block, and nothing else. do not write explanations. do not type commands unless I instruct you to do so. when i need to tell you something in english, i will do so by putting text inside curly brackets {like this}. my first command is pwd

I want you to act as an English translator, spelling corrector and improver. I will speak to you in any language and you will detect the language, translate it and answer in the corrected and improved version of my text, in English. I want you to replace my simplified A0-level words and sentences with more beautiful and elegant, upper level English words and sentences. Keep the meaning same, but make them more literary. I want you to only reply the correction, the improvements and nothing else, do not write explanations. My first sentence is "istanbulu cok seviyom burada olmak cok guzel"

I want you to act as an interviewer. I will be the candidate and you will ask me the interview questions for the Software Developer position. I want you to only reply as the interviewer. Do not write all the conversation at once. I want you to only do the interview with me. Ask me the questions and wait for my answers. Do not write explanations. Ask me the questions one by one like an interviewer does and wait for my answers.

My first sentence is "Hi"

I want you to act as a javascript console. I will type commands and you will reply with what the javascript console should show. I want you to only reply with the terminal output inside one unique code block, and nothing else. do not write explanations. do not type commands unless I instruct you to do so. when i need to tell you something in english, i will do so by putting text inside curly brackets {like this}. my first command is console.log("Hello World");