pr-title.yml

name: PR Title

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

permissions:
  contents: read
  pull-requests: read

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

jobs:
  validate-title:
    name: Validate PR title
    runs-on: ubuntu-latest

    steps:
      - name: Validate title format
        uses: actions/github-script@v8
        with:
          script: |
            const title = context.payload.pull_request.title;
            const pattern = /^(feat|fix|docs|refactor|perf|test|build|ci|chore|revert)(\([a-z0-9][a-z0-9-]*\))?: (.+)$/;
            const match = title.match(pattern);

            if (match) {
              const summary = match[3];
              const trimmed = summary.trim();
              const startsLowercase = /^[a-z]/.test(trimmed);
              const hasTrailingPeriod = trimmed.endsWith('.');
              const withinLimit = title.length <= 72;

              if (startsLowercase && !hasTrailingPeriod && withinLimit) {
                core.info(`PR title is valid: "${title}"`);
                return;
              }
            }

            core.setFailed(
              [
                `Invalid PR title: "${title}"`,
                '',
                'Expected format:',
                'type(scope): short summary',
                '',
                'Allowed types:',
                'feat, fix, docs, refactor, perf, test, build, ci, chore, revert',
                '',
                'Examples:',
                '- ci(docs): add next build check for docs changes',
                '- fix(dialog): restore focus after nested close',
                '- docs(installation): clarify pnpm-only docs setup',
                '',
                'Rules:',
                '- scope is optional',
                '- use lowercase type and scope',
                '- summary should start lowercase',
                '- no trailing period',
                '- keep the full title under 72 characters'
              ].join('\n')
            );