CLAUDE.md

Development Guidelines

This document contains critical information about working with this codebase. Follow these guidelines precisely.

Core Development Rules

1. Package Management

   • ONLY use uv, NEVER pip
   • Installation: uv add package
   • Running tools: uv run tool
   • Upgrading: uv add --dev package --upgrade-package package
   • FORBIDDEN: uv pip install, @latest syntax

2. Code Quality

   • Type hints required for all code
   • Public APIs must have docstrings
   • Functions must be focused and small
   • Follow existing patterns exactly
   • Line length: 120 chars maximum

3. Testing Requirements

   • Framework: uv run --frozen pytest
   • Async testing: use anyio, not asyncio
   • Coverage: test edge cases and errors
   • New features require tests
   • Bug fixes require regression tests

• For commits fixing bugs or adding features based on user reports add:

  git commit --trailer "Reported-by:<name>"

  Where <name> is the name of the user.

• For commits related to a Github issue, add

  git commit --trailer "Github-Issue:#<number>"

• NEVER ever mention a co-authored-by or similar aspects. In particular, never mention the tool used to create the commit message or PR.

Pull Requests

• Create a detailed message of what changed. Focus on the high level description of the problem it tries to solve, and how it is solved. Don't go into the specifics of the code unless it adds clarity.

• Always add jerome3o-anthropic and jspahrsummers as reviewer.

• NEVER ever mention a co-authored-by or similar aspects. In particular, never mention the tool used to create the commit message or PR.

Python Tools

Code Formatting

1. Ruff

   • Format: uv run --frozen ruff format .
   • Check: uv run --frozen ruff check .
   • Fix: uv run --frozen ruff check . --fix
   • Critical issues:
     • Line length (88 chars)
     • Import sorting (I001)
     • Unused imports
   • Line wrapping:
     • Strings: use parentheses
     • Function calls: multi-line with proper indent
     • Imports: split into multiple lines

2. Type Checking

   • Tool: uv run --frozen pyright
   • Requirements:
     • Explicit None checks for Optional
     • Type narrowing for strings
     • Version warnings can be ignored if checks pass

3. Pre-commit

   • Config: .pre-commit-config.yaml
   • Runs: on git commit
   • Tools: Prettier (YAML/JSON), Ruff (Python)
   • Ruff updates:
     • Check PyPI versions
     • Update config rev
     • Commit config first

Error Resolution

1. CI Failures

   • Fix order:
     1. Formatting
     2. Type errors
     3. Linting
   • Type errors:
     • Get full line context
     • Check Optional types
     • Add type narrowing
     • Verify function signatures

2. Common Issues

   • Line length:
     • Break strings with parentheses
     • Multi-line function calls
     • Split imports
   • Types:
     • Add None checks
     • Narrow string types
     • Match existing patterns
   • Pytest:
     • If the tests aren't finding the anyio pytest mark, try adding PYTEST_DISABLE_PLUGIN_AUTOLOAD="" to the start of the pytest run command eg: PYTEST_DISABLE_PLUGIN_AUTOLOAD="" uv run --frozen pytest

3. Best Practices

   • Check git status before commits
   • Run formatters before type checks
   • Keep changes minimal
   • Follow existing patterns
   • Document public APIs
   • Test thoroughly

Exception Handling

• Always use logger.exception() instead of logger.error() when catching exceptions
  • Don't include the exception in the message: logger.exception("Failed") not logger.exception(f"Failed: {e}")
• Catch specific exceptions where possible:
  • File ops: except (OSError, PermissionError):
  • JSON: except json.JSONDecodeError:
  • Network: except (ConnectionError, TimeoutError):
• Only catch Exception for:
  • Top-level handlers that must not crash
  • Cleanup blocks (log at debug level)