labeler.yml

name: PR Labeler

# Auto-labels pull requests based on changed file paths.
# Type labels (bug, enhancement, etc.) are applied by the separate
# "Label by PR title" job below, derived from the Conventional Commit title.
# "status: waiting triage" is applied to newly opened PRs from contributors —
# maintainer-authored PRs (OWNER / MEMBER) are skipped.
#
# Uses pull_request_target so labeling works for fork PRs.
# The base repo token is used; PR code is never checked out.

on:
  pull_request_target:
    types: [opened, synchronize, reopened, edited]

permissions:
  contents: read
  pull-requests: write
  issues: write

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  paths:
    name: Label by changed files
    runs-on: ubuntu-latest
    steps:
      - uses: actions/labeler@v6
        with:
          repo-token: ${{ secrets.GITHUB_TOKEN }}
          configuration-path: .github/labeler.yml
          # Additive only — never strip labels. With sync-labels: true the path
          # job removed any label not in labeler.yml, which raced the title job
          # below and silently deleted its type labels (Bug/enhancement/chore) on
          # synchronize/edit. Labels are only ever added now; removing them is a
          # maintainer's call, not the bot's.
          sync-labels: false

  type:
    name: Label by PR title
    runs-on: ubuntu-latest
    # The type label comes from the title, which only changes on open/edit —
    # skip synchronize (new commits) so we don't re-run for nothing.
    if: github.event.action != 'synchronize'
    steps:
      - name: Map Conventional Commit type to label
        uses: actions/github-script@v9
        with:
          script: |
            const title = context.payload.pull_request.title || '';
            const match = title.match(/^(\w+)(?:\([^)]*\))?!?:/);
            if (!match) return;

            const map = {
              feat:     'enhancement',
              fix:      'Bug',
              docs:     'documentation',
              perf:     'performance',
              refactor: 'refactor',
              test:     'tests',
              build:    'dependencies',
              ci:       'area: ci',
              chore:    'chore',
              style:    'chore',
              revert:   'Bug',
            };

            const label = map[match[1].toLowerCase()];
            if (label) {
              await github.rest.issues.addLabels({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.payload.pull_request.number,
                labels: [label],
              });
            }

            if (/^(\w+)(?:\([^)]*\))?!:/.test(title)) {
              await github.rest.issues.addLabels({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.payload.pull_request.number,
                labels: ['scope: breaking'],
              });
            }

  triage:
    name: Mark new PRs for triage
    runs-on: ubuntu-latest
    # Skip PRs opened by a repo owner or org member — already triaged.
    if: >-
      github.event.action == 'opened' &&
      github.event.pull_request.author_association != 'OWNER' &&
      github.event.pull_request.author_association != 'MEMBER'
    steps:
      - uses: actions/github-script@v9
        with:
          script: |
            await github.rest.issues.addLabels({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.payload.pull_request.number,
              labels: ['status: waiting triage'],
            });