perf.yml

name: Performance Tests
on:
  push:
    branches:
      - main
  pull_request:
    paths-ignore:
      - '**.md'

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

jobs:
  perf:
    name: Continuous Integration
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1

      - name: Setup Bun
        uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2.2.0
        with:
          bun-version: "1.3.6"

      - name: Install dependencies
        run: bun install --frozen-lockfile

      - name: Install Playwright browsers
        run: bunx --bun playwright install --with-deps chromium

      - name: Build
        run: bunx --bun turbo run build

      # ── PR: download baseline from main ────────────────────────
      - name: Download baseline from main
        if: github.event_name == 'pull_request'
        id: baseline
        uses: dawidd6/action-download-artifact@b6e2e70617bc3265edd6dab6c906732b2f1ae151 # v21
        with:
          name: perf-baseline
          workflow: perf.yml
          branch: main
          path: apps/host/tests/performance/results
          if_no_artifact_found: warn

      - name: Rename baseline
        if: github.event_name == 'pull_request'
        run: |
          if [ -f apps/host/tests/performance/results/last.json ]; then
            mv apps/host/tests/performance/results/last.json apps/host/tests/performance/results/base.json
            echo "HAVE_BASE=true" >> "$GITHUB_ENV"
          else
            echo "HAVE_BASE=false" >> "$GITHUB_ENV"
            echo "::warning::No baseline found — run will be recorded without comparison"
          fi

      # ── Run perf tests ─────────────────────────────────────────
      # On main: long run (baseline). On PR: shorter run (compare).
      - name: Run perf tests (baseline)
        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
        working-directory: apps/host
        env:
          PERF_RUNS: "20"
          PERF_SAVE_BASE: "1"
          PERF_DOMAIN_A: explore
          PERF_DOMAIN_B: host-playground
        run: bunx --bun playwright test --config=tests/performance/playwright.config.ts tests/performance/cold-start.spec.ts || true

      - name: Run perf tests (PR)
        if: github.event_name == 'pull_request'
        working-directory: apps/host
        env:
          PERF_RUNS: "10"
          PERF_DOMAIN_A: explore
          PERF_DOMAIN_B: host-playground
        run: bunx --bun playwright test --config=tests/performance/playwright.config.ts tests/performance/cold-start.spec.ts || true

      # ── main: upload baseline artifact ─────────────────────────
      - name: Upload baseline artifact
        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
        with:
          name: perf-baseline
          path: apps/host/tests/performance/results/last.json
          retention-days: 90
          overwrite: true

      # ── PR: build comparison report and comment ────────────────
      - name: Generate comparison
        if: github.event_name == 'pull_request' && env.HAVE_BASE == 'true'
        working-directory: apps/host
        run: bun tests/performance/compare.ts --markdown > /tmp/perf-comment.md || true

      - name: Generate standalone report
        if: github.event_name == 'pull_request' && env.HAVE_BASE != 'true'
        run: |
          cat <<'EOF' > /tmp/perf-comment.md
          ## ⚡ Performance Report

          > ⚠️ No baseline found on `main`. This PR's results are recorded but cannot be compared.
          > Merge to `main` to establish a baseline.
          EOF

      - name: Post or update PR comment
        if: github.event_name == 'pull_request'
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          script: |
            const fs = require('fs');
            const body = fs.readFileSync('/tmp/perf-comment.md', 'utf8');
            const marker = '## ⚡ Performance Report';

            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });

            const existing = comments.find(c => c.body?.includes(marker));

            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body,
              });
            }