pre-commit.yml

name: Scheduled Pre-Commit Auto-Update

"on":
  schedule:
    # 06:00 UTC on the 1st of every month
    - cron: "0 6 1 * *"
  # Manual trigger from the Actions tab
  workflow_dispatch:

# Serialize scheduled and manual runs: avoids duplicate work and push races
concurrency:
  group: pre-commit-autoupdate
  cancel-in-progress: false

jobs:
  auto-update:
    runs-on: ubuntu-latest
    timeout-minutes: 10

    # Needed for GITHUB_TOKEN to commit and push the updated config
    permissions:
      contents: write

    steps:
      - name: Checkout repository
        uses: actions/checkout@v6
        with:
          # Full history avoids shallow-clone issues on push
          fetch-depth: 0

      - name: Set up latest Python
        uses: actions/setup-python@v6
        with:
          # Floating spec: resolves to the latest stable Python 3 on every run
          python-version: "3.x"

      - name: Install pre-commit
        # No `pip install --upgrade pip`: setup-python already ships a current
        # pip, and the upgrade costs ~15s on every run for no benefit here.
        run: pip install pre-commit

      - name: Cache pip and pre-commit
        # NOTE: setup-python's built-in `cache: pip` is intentionally NOT used:
        # it keys off requirements*.txt files, which this repo doesn't have,
        # so it would silently do nothing. This explicit step actually caches.
        uses: actions/cache@v5
        with:
          path: |
            ~/.cache/pip
            ~/.cache/pre-commit
          key: pre-commit-${{ runner.os }}-${{ hashFiles('.pre-commit-config.yaml') }}
          restore-keys: |
            pre-commit-${{ runner.os }}-

      - name: Run pre-commit autoupdate
        id: autoupdate
        run: |
          pre-commit autoupdate

          # Detect changes (step output, not env var)
          if git diff --quiet -- .pre-commit-config.yaml; then
            echo "changes=false" >> "$GITHUB_OUTPUT"
            echo "No pre-commit updates available."
          else
            echo "changes=true" >> "$GITHUB_OUTPUT"
            echo "Pre-commit updates detected:"
            git diff --stat -- .pre-commit-config.yaml
          fi

      - name: Commit and push updates
        if: steps.autoupdate.outputs.changes == 'true'
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git add .pre-commit-config.yaml
          # Only commit if staged content differs (avoids empty-commit race)
          if git diff --cached --quiet; then
            echo "Nothing staged, skipping commit."
          else
            git commit -m "chore(deps): auto-update pre-commit hooks"
            git push
          fi