pre-commit.md

Pre-commit hooks

A local gate that runs ruff and ty before each commit, so CI (templates.md) rarely fails on something a hook would have caught. pre-commit is installed as a global tool (see MAC.md), not a project dependency.

Wire it up (once per clone):

pre-commit install            # install the git hook
pre-commit run --all-files    # run against the whole repo the first time

.pre-commit-config.yaml:

repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.0          # keep in sync with the ruff version in pyproject.toml
    hooks:
      - id: ruff-check
        args: [--fix]
      - id: ruff-format

  - repo: local
    hooks:
      - id: ty
        name: ty
        entry: uv run ty check
        language: system
        types: [python]
        pass_filenames: false

  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v5.0.0
    hooks:
      - id: trailing-whitespace
      - id: end-of-file-fixer
      - id: check-yaml
      - id: check-toml
      - id: check-added-large-files
      - id: check-merge-conflict

Rules:

• Pin every rev: and bump deliberately — same stance as deps (pyproject.md) and the pinned setup-uv in CI (templates.md). pre-commit autoupdate bumps them all at once; review the diff.
• Keep the ruff-pre-commit rev in sync with the ruff dev dependency so the hook and CI apply identical rules. A mismatch means "passes locally, fails in CI."
• ty runs as a local system hook (uv run ty check), not a mirrored repo, because it must execute in your project venv where your deps and their type information live. pass_filenames: false because ty checks the whole project, not just the staged files.
• The hook is a fast gate, not the enforcer. It can be skipped (git commit -n), so CI (templates.md) stays the source of truth. Run the same tools in both and don't let them drift.