8.3Multi-Stage Performance Pipeline

For mature teams, performance validation should be a multi-stage process:

# .github/workflows/performance-gates.yml
name: Performance Gates
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  # Stage 1: Build-time checks (fast, every PR)
  build-time-budget:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci && npm run build

      - name: Check bundle sizes
        run: npx bundlesize --config bundlesize.config.json

      - name: Check for new dependencies > 50KB
        run: |
          npx webpack-bundle-analyzer dist/stats.json \
            --mode json --no-open -r bundle-report.json
          node scripts/check-large-deps.js bundle-report.json

  # Stage 2: Lighthouse audit (medium speed, every PR)
  lighthouse-audit:
    needs: build-time-budget
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci && npm run build

      - name: Start local server
        run: npm run serve &
        env:
          PORT: 3000

      - name: Wait for server
        run: npx wait-on http://localhost:3000 --timeout 30000

      - name: Run Lighthouse CI
        uses: treosh/lighthouse-ci-action@v11
        with:
          urls: |
            http://localhost:3000/
            http://localhost:3000/products/1
          configPath: ./lighthouserc.json

  # Stage 3: API performance (on merge to main only)
  api-performance:
    if: github.event_name == 'push'
    needs: [build-time-budget, lighthouse-audit]
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Run k6 API performance tests
        uses: grafana/k6-action@v0.4.0
        with:
          filename: tests/performance/api-budget.js
          flags: --out json=k6-results.json
        env:
          K6_TARGET_URL: ${{ secrets.STAGING_URL }}

      - name: Validate k6 thresholds
        run: |
          # k6 exits non-zero if thresholds fail
          echo "k6 thresholds validated successfully"

      - name: Upload results
        uses: actions/upload-artifact@v4
        with:
          name: k6-api-budget-results
          path: k6-results.json