commitlint.yml

# Enforce Conventional Commits on every PR to the default branch (and the PR title).
# Reads commitlint.config.mjs at the repo root (extends @commitlint/config-conventional).
# No local install needed — the action bundles commitlint. See CLAUDE.md §3.2.
name: Commitlint

on:
  pull_request:
    branches:
      - develop
      - main
    types: [opened, edited, synchronize, reopened]

concurrency:
  group: ${{ github.ref }}-${{ github.workflow }}
  cancel-in-progress: true

permissions:
  contents: read
  pull-requests: read

jobs:
  commitlint:
    name: Lint commit messages
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      # A main-base PR is a develop -> main release cut: every commit in main..develop
      # was already linted at its own PR, while that commit was still mutable and its
      # author could still fix it. Re-linting the whole inherited range at cut time adds
      # no information and cannot be satisfied (the commits are now immutable, pinned by
      # gitlinks and rev-pinned deps). Lint only what THIS PR introduces: its own commit(s).
      - name: Lint PR commits (release cut — this PR's own commits only)
        if: github.base_ref == 'main'
        uses: wagoid/commitlint-github-action@v6
        with:
          configFile: commitlint.config.mjs
          commitDepth: 1

      - name: Lint PR commits (feature branch — full PR range)
        if: github.base_ref != 'main'
        uses: wagoid/commitlint-github-action@v6
        with:
          configFile: commitlint.config.mjs

      - name: Lint PR title
        if: github.event_name == 'pull_request'
        env:
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          set -euo pipefail
          # Install both @commitlint/cli AND the extended shareable config so the
          # `extends: ['@commitlint/config-conventional']` in commitlint.config.mjs resolves.
          # GitHub's squash merge lands "$PR_TITLE (#$PR_NUMBER)" as the commit subject —
          # lint that exact string, not the title alone, or a title within the length
          # limit can still produce an over-limit commit subject once merged.
          printf '%s (#%s)\n' "$PR_TITLE" "$PR_NUMBER" | npx --yes -p @commitlint/cli -p @commitlint/config-conventional \
            commitlint --config commitlint.config.mjs