ci.yml

name: CI

on:
  push:
    branches: [main]
  pull_request:
  workflow_dispatch:
  schedule:
    # Weekly. Chrome stable ships roughly monthly, so this catches a behaviour
    # change within days of release rather than whenever someone next builds.
    - cron: '0 6 * * 1'

jobs:
  typecheck:
    # Its own job, not a step in `test`: it needs no Chrome, so it answers in
    # under a minute instead of after a browser download. The mcp package is
    # bundled by esbuild alone, which strips types without reading them — this
    # is the only thing that type-checks it at all.
    name: typecheck
    runs-on: ubuntu-latest
    timeout-minutes: 10

    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: npm

      - run: npm ci

      # Builds first: mcp imports its siblings by package name, which resolve
      # to their built declarations.
      - run: npm run typecheck

  test:
    name: test (Chrome ${{ matrix.chrome }})
    runs-on: ubuntu-latest
    timeout-minutes: 15
    strategy:
      fail-fast: false
      matrix:
        # The version every claim in the README was measured against. Pinned so
        # a Chrome release cannot silently change what this project asserts.
        chrome: ['151.0.7922.71']

    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: npm

      - run: npm ci

      - name: Install Chrome ${{ matrix.chrome }}
        run: |
          # Prints "chrome@<version> <path>"; the path is the last field.
          OUT=$(npx --yes @puppeteer/browsers install "chrome@${{ matrix.chrome }}")
          echo "$OUT"
          echo "CHROME_PATH=${OUT##* }" >> "$GITHUB_ENV"

      - run: npm run build:all

      - name: Test
        run: npm test

  drift:
    name: drift check (Chrome stable)
    # Separate from `test` on purpose: a Chrome release changing behaviour is
    # something to learn about, not a reason to block an unrelated pull request.
    if: github.event_name == 'schedule' || github.event_name == 'workflow_dispatch'
    runs-on: ubuntu-latest
    timeout-minutes: 15

    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: npm

      - run: npm ci

      - name: Install Chrome stable
        run: |
          OUT=$(npx --yes @puppeteer/browsers install chrome@stable)
          echo "$OUT"
          echo "CHROME_PATH=${OUT##* }" >> "$GITHUB_ENV"
          echo "CHROME_VERSION=$(echo "$OUT" | cut -d' ' -f1)" >> "$GITHUB_ENV"

      - run: npm run build:all

      - name: Test against Chrome stable
        run: npm test

      - name: Explain a failure
        if: failure()
        run: |
          echo "::warning title=Chrome stable drift::${CHROME_VERSION} behaves differently from the pinned build."
          echo "The platform-assumptions test prints what it measured at each worker pause point."
          echo "Injection depends on undocumented behaviour: workers pause before their first line,"
          echo "the beforeScriptExecution breakpoint exists, and codecs are absent at the earlier pause."
          echo "A change there is a heads-up, not necessarily a defect — read the measurement first."