FastMCP
# 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: 88 chars maximum
3. Testing Requirements
- Framework: `uv run pytest`
- Async testing: use anyio, not asyncio
- Coverage: test edge cases and errors
- New features require tests
- Bug fixes require regression tests
4. Version Control
- Commit messages: conventional format (fix:, feat:)
- PR scope: minimal, focused changes
- PR requirements: description, test plan
- Always include issue numbers
- Quote handling:
```bash
git commit -am "\"fix: message\""
gh pr create --title "\"title\"" --body "\"body\""
```
## Code Formatting
1. Ruff
- Format: `uv run ruff format .`
- Check: `uv run ruff check .`
- Fix: `uv run 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 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
3. Best Practices
- Check git status before commits
- Run formatters before type checks
- Keep changes minimal
- Follow existing patterns
- Document public APIs
- Test thoroughly