CPython Skills Marketplace

A Claude Code marketplace providing specialized skills for working with the CPython repository - the reference implementation of the Python programming language.

Overview

This marketplace hosts Claude Code plugins with AI-agent skills for CPython development. Currently includes one comprehensive plugin with multiple skills providing deep knowledge about CPython's codebase structure, build system, testing infrastructure, and coding standards.

Upgrading from v0.3.x

If you previously installed cpython-skills, it has been renamed to cpython for cleaner invocation:

/plugin uninstall cpython-skills
/plugin install cpython

Skills are now invoked as cpython:dev, cpython:build, etc. instead of cpython-skills:cpython-*.

Installation

To use these skills in Claude Code within a CPython repository checkout:

1. Add the marketplace:

   /plugin marketplace add gpshead/cpython-skills
   

2. Install the plugin:

   /plugin install cpython
   

3. In your CPython repository, ask Claude:

   write a CLAUDE.local.md that instructs you to load and use all of the cpython plugin skills in this repo.
   

Available Plugins

CPython Skills

Name: cpython Description: Skills for working with the CPython repository - helping with building, testing, and contributing to Python's implementation

This plugin provides four specialized skills with a meta-skill that coordinates loading:

1. dev (Entry Point)

When to use: Starting any CPython development task - fixing bugs, adding features, understanding code

Provides:

• Codebase orientation and source code structure
• Workflow coordination - guides you to load other skills as needed
• Recommended tools (rg, gh, jq)
• Engineering notebook management for PRs and branches
• Scratch space usage

2. build

When to use: Compiling CPython, running tests, verifying changes work, debugging test failures

Includes:

• Build directory setup with ccache support
• Platform-specific configuration (Linux, macOS, Windows)
• Argument Clinic code generation
• Build verification and troubleshooting
• unittest-based testing (not pytest!)
• Using --match for test filtering (not -k!)
• Code coverage collection
• Interactive debugging with tmux

3. style

When to use: Preparing commits, running pre-commit hooks, validating changes

Covers:

• PEP 7 (C code) and PEP 8 (Python code) compliance
• Trailing whitespace and file ending rules
• Type annotation policy (no annotations in Lib/!)
• Pre-commit hooks and patchcheck

4. docs

When to use: Editing documentation in Doc/, adding version markers, creating NEWS entries

Covers:

• Documentation in ReST format in Doc/ tree
• Documentation tooling setup and validation
• Version markers (always use next)
• NEWS file entries for bug fixes and features

Recommended Tools

These tools improve the agentic development experience: rg, gh, jq

Marketplace Structure

cpython-skills/
├── .claude-plugin/
│   └── marketplace.json    # Marketplace manifest
├── plugins/
│   └── cpython-skills/     # CPython skills plugin
│       ├── plugin.json     # Plugin manifest
│       └── skills/         # Individual skills
│           ├── dev/            # Entry point + codebase orientation
│           │   └── SKILL.md
│           ├── build/          # Building and testing
│           │   └── SKILL.md
│           ├── style/          # Code style and validation
│           │   └── SKILL.md
│           └── docs/           # Documentation
│               └── SKILL.md
├── LICENSE
└── README.md               # This file

For Plugin Developers

Adding New Plugins to This Marketplace

To add a new plugin to this marketplace:

1. Create a new directory under plugins/ with your plugin name
2. Add your plugin files (skills, commands, agents, etc.)
3. Create a plugin.json manifest in your plugin directory
4. Update .claude-plugin/marketplace.json to include your plugin entry

Example marketplace.json plugin entry:

{
  "name": "your-plugin-name",
  "source": "./plugins/your-plugin-name",
  "description": "Brief description of what your plugin does"
}

Skills Format

This marketplace follows the Claude Skills specification, making plugins usable by any AI agent that supports this format.

Each skill is a self-contained directory with a SKILL.md file containing:

• YAML frontmatter with name and description
• Markdown content with detailed instructions

Usage Examples

When working with CPython, the AI agent will:

1. Load dev when starting work in the repo - provides orientation and workflow guidance
2. Load build when you need to compile or run tests - the dev skill prompts this
3. Load style when preparing commits - the dev skill prompts this
4. Load docs when updating documentation - the dev skill prompts this

The dev skill acts as a coordinator, explicitly guiding the agent to load specialized skills as your workflow progresses.

Origin

This marketplace was created from the original CPython skills plugin, which was converted from the cpython/CLAUDE.local.md file. The marketplace-based approach provides:

• Modularity: Each skill focuses on a specific domain
• Discoverability: AI agents can find relevant skills based on task descriptions
• Reusability: Skills can be used independently or together
• Extensibility: Easy to add new plugins to the marketplace
• Interoperability: Works with any agent supporting Claude Skills format

License

CC0 1.0 Universal

References

• Claude Code Plugin Marketplaces Documentation
• Claude Code Plugins Documentation
• Claude Code Skills Documentation
• Simon Willison on Claude Skills
• CPython Developer Guide