commit-message-check.yml

name: Commit Message Check

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

permissions:
  contents: read

jobs:
  check-pr-title:
    name: pr-title-check
    if: github.event_name == 'pull_request'
    runs-on: ubuntu-latest
    steps:
      - name: Validate PR title against Conventional Commits
        env:
          PR_TITLE: ${{ github.event.pull_request.title }}
        run: |
          set -euo pipefail
          pattern='^(feat|fix|chore|docs|test|refactor|perf|style|build|ci|revert|release)(\([a-z0-9_./-]+\))?!?: .+'
          if [[ ! "$PR_TITLE" =~ $pattern ]]; then
            {
              echo "::error title=PR title invalid::PR title does not match Conventional Commits"
              echo ""
              echo "PR title: $PR_TITLE"
              echo ""
              echo "PRs are squash-merged into main, so the PR title becomes the commit"
              echo "subject on main. It must follow Conventional Commits."
              echo ""
              echo "Required format: <type>(<optional-scope>)<!>: <description>"
              echo ""
              echo "Allowed types: feat, fix, chore, docs, test, refactor, perf, style,"
              echo "               build, ci, revert, release."
              echo ""
              echo "Examples:"
              echo "  feat(api): add idempotency-key header"
              echo "  fix(core): reject on malformed JSON instead of crashing"
              echo "  chore(deps): bump c8 to ^10.1.4"
              echo ""
              echo "How to fix: edit the PR title in the GitHub UI; the workflow"
              echo "will re-run automatically on the 'edited' event."
            } >&2
            exit 1
          fi
          echo "PR title OK: $PR_TITLE"

  check-pr-branch:
    name: branch-name-check
    if: github.event_name == 'pull_request'
    runs-on: ubuntu-latest
    steps:
      - name: Validate PR branch against semantic branch convention
        env:
          HEAD_REF: ${{ github.event.pull_request.head.ref }}
        run: |
          set -euo pipefail
          branch_pattern='^([a-z0-9][a-z0-9._-]*/)?(feat|fix|chore|docs|test|refactor|perf|style|build|ci|revert)/[a-z0-9][a-z0-9._-]*(/[a-z0-9][a-z0-9._-]*)*$'
          release_pattern='^release/v[0-9]+\.[0-9]+\.[0-9]+$'

          case "$HEAD_REF" in
            main|master|develop|dev|trunk|dependabot/*|renovate/*|github-actions/*)
              echo "PR branch OK: $HEAD_REF"
              exit 0
              ;;
          esac

          if [[ "$HEAD_REF" =~ $branch_pattern || "$HEAD_REF" =~ $release_pattern ]]; then
            echo "PR branch OK: $HEAD_REF"
            exit 0
          fi

          {
            echo "::error title=PR branch invalid::PR branch does not match the semantic branch convention"
            echo ""
            echo "PR branch: $HEAD_REF"
            echo ""
            echo "Required branch format:"
            echo "  <type>/<slug>"
            echo "  <namespace>/<type>/<slug>"
            echo "  release/vX.Y.Z"
            echo ""
            echo "Allowed types: feat, fix, chore, docs, test, refactor, perf, style,"
            echo "               build, ci, revert."
            echo ""
            echo "Examples:"
            echo "  feat/semantic-git-hooks"
            echo "  fix/pre-push-range"
            echo "  codex/chore/enforce-git-conventions"
            echo "  release/v1.7.0"
          } >&2
          exit 1

  check-commits:
    name: commit-subjects-check
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          fetch-depth: 0

      - name: Validate commit subjects in range
        env:
          EVENT_NAME: ${{ github.event_name }}
          PR_BASE: ${{ github.event.pull_request.base.sha }}
          PR_HEAD: ${{ github.event.pull_request.head.sha }}
          PUSH_BEFORE: ${{ github.event.before }}
          PUSH_AFTER: ${{ github.event.after }}
        run: |
          set -euo pipefail
          pattern='^(feat|fix|chore|docs|test|refactor|perf|style|build|ci|revert|release)(\([a-z0-9_./-]+\))?!?: .+'

          if [ "$EVENT_NAME" = "pull_request" ]; then
            range="$PR_BASE..$PR_HEAD"
          else
            zero='0000000000000000000000000000000000000000'
            if [ "$PUSH_BEFORE" = "$zero" ]; then
              range="$PUSH_AFTER~1..$PUSH_AFTER"
            else
              range="$PUSH_BEFORE..$PUSH_AFTER"
            fi
          fi

          fail=0
          while IFS= read -r line; do
            sha="${line%% *}"
            subject="${line#* }"
            case "$subject" in
              Merge\ *|Revert\ *|fixup!*|squash!*|amend!*) continue ;;
            esac
            if [[ ! "$subject" =~ $pattern ]]; then
              echo "::error title=Commit ${sha:0:8} invalid::$subject"
              fail=1
            fi
          done < <(git log --format='%H %s' "$range")

          if [ "$fail" -ne 0 ]; then
            {
              echo ""
              echo "One or more commit subjects do not match Conventional Commits."
              echo ""
              echo "Required format: <type>(<optional-scope>)<!>: <description>"
              echo "Allowed types: feat, fix, chore, docs, test, refactor, perf, style,"
              echo "               build, ci, revert, release."
              echo ""
              echo "Examples:"
              echo "  feat(api): add idempotency-key header"
              echo "  fix(core): reject on malformed JSON instead of crashing"
              echo ""
              echo "How to fix on a PR: rewrite the offending commits with"
              echo "    git rebase -i origin/main"
              echo "and change 'pick' to 'reword' on each one. Then force-push the branch."
            } >&2
            exit 1
          fi
          echo "All commit subjects OK."