Python Conventions

Apply these conventions when working on Python files or projects.

Dispatch

References

Tooling

• Package manager: uv for all Python operations (uv run python ... instead of python, uv add instead of pip install)
• Project config: pyproject.toml with uv add <pkg> (never uv pip install or pip install)
• Type checking: ty (not mypy)
• Linting: ruff check and ruff format
• Testing: uv run pytest
• Task running: uv run <command> for all script execution

Virtual Environments

• Let uv manage virtual environments automatically
• Never manually create or activate .venv directories
• Use uv run to execute within the project environment

Preferred Libraries

When applicable, prefer these libraries over alternatives:

Project Structure

• Use pyproject.toml for all project metadata and dependencies
• Place source code in a package directory matching the project name
• Use uv workspace members for monorepo sub-packages
• Run ruff check and ruff format before committing

Critical Rules

1. Always use uv for package management -- never pip install or pip
2. Use uv add to add dependencies -- never uv pip install
3. Use ty for type checking -- never mypy
4. Run uv run pytest before committing any Python changes
5. Run uv run ruff check to lint before committing
6. Check references/exceptions.md before breaking any convention
7. Prefer libraries from the preferred table over their alternatives

Canonical terms (use these exactly):

• uv -- the required package manager and task runner
• ty -- the required type checker (not mypy)
• ruff -- the required linter and formatter
• pyproject.toml -- the single source of project configuration
• uv run -- prefix for all Python command execution