experiment.yaml

name: Next-Gen CI Prototype

on:
  pull_request:
    branches: [ main ]

# 1. CONCURRENCY: Stop burning money on abandoned commits
concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
  cancel-in-progress: true

jobs:
  discover:
    runs-on: ubuntu-latest
    outputs:
      packages: ${{ steps.changes.outputs.all_changed_files }}
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
          
      - name: Detect Changed Packages
        id: changes
        uses: tj-actions/changed-files@v44
        with:
          files: packages/** # Only watch the packages directory
          dir_names: true             # Return folder names, not files
          dir_names_max_depth: 2      # Strip it down to just "google-cloud-storage"
          json: true                  # Output a perfect JSON array for the matrix
          escape_json: false

  # 3. EXECUTION: Native Fan-out Matrix
  unit-test:
    needs: discover
    if: ${{ needs.discover.outputs.packages != '[]' }}
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false # Don't kill the whole matrix if one package fails
      matrix:
        package: ${{ fromJSON(needs.discover.outputs.packages) }}
        # Risk-Tiering: Smoke test on presubmit to save money
        python: ["3.11"] 
    
    steps:
      - uses: actions/checkout@v4

      # 4. THE ENGINE SWAP: Rust-based uv instead of setup-python + pip
      - name: Install uv and Python
        uses: astral-sh/setup-uv@v5
        with:
          python-version: ${{ matrix.python }}
          enable-cache: true
          cache-dependency-glob: "packages/${{ matrix.package }}/setup.py"

      - name: Execute Tests (High-Density)
        run: |
          cd packages/${{ matrix.package }}
          
          # Force Nox to natively use uv instead of the legacy virtualenv module
          export NOX_DEFAULT_VENV_BACKEND=uv
          
          echo "Running targeted tests for ${{ matrix.package }} on Python ${{ matrix.python }}"
          
          # Use uvx to run nox (with the uv plugin injected to guarantee compatibility)
          uvx --with 'nox[uv]' nox -s unit-${{ matrix.python }}