name: parity-main
# The vanilla harnesses on main, a batch of merges at a time (docs/release-flow.md#parity-on-main), on the Mac mini's
# runner. One run at a time: merges that land while a run goes on wait in one pending run (GitHub keeps only the
# newest), which checks every merge since main's last green parity-main (tools/parity_main.py base). On a failure it
# bisects the failing harnesses over those merges and comments on the pull request that broke them. Releases ship
# only a commit whose parity-main passed (tools/release_train.py), so nothing a harness catches reaches players.
on:
  push:
    branches: [main]
  workflow_dispatch:
permissions:
  contents: read
  # The comment on the merge that broke a harness.
  pull-requests: write
  # tools/parity_main.py base reads earlier runs.
  actions: read
concurrency:
  group: parity-main
  cancel-in-progress: false
env:
  # Test runs never reach the telemetry server: no live-count ping, no uploads (docs/telemetry.md).
  HORIZON_TELEMETRY_URL: "off"

jobs:
  parity-main:
    # A Mac mini runner of its own (ludovics-mac-mini-2 holds only this label since 2026-10-26): behind PR parity jobs
    # this run waited 2 h while every merge replaced the pending one, and on the release runner a release then waited
    # behind the next run. PR parity jobs have ludovics-mac-mini and playhorizon. Not playhorizon: its 4 CPUs
    # make a core-crate run several times longer, and a failure here bisects and comments on merges.
    runs-on: [self-hosted, macOS, horizon-parity-main]
    timeout-minutes: 240  # a core-crate batch reruns ~300 harnesses (~60-90 min), a bisect a few rounds of the failures
    steps:
      - uses: actions/checkout@v4
        with:
          ref: ${{ github.sha }}
          fetch-depth: 0
          persist-credentials: false
          # Keeps .local/ (parity state, probe builds, oracle results) and target/ between runs.
          clean: false
      - uses: dtolnay/rust-toolchain@stable
      - name: Tools from the runner
        run: bash tools/ci/runner-env.sh
      - name: Vanilla data, and resources prepared by this preparer
        run: bash tools/ci/vanilla-data.sh
      - name: Main's last green parity-main
        id: base
        env:
          GH_TOKEN: ${{ github.token }}
        run: echo "sha=$(python3 tools/parity_main.py base)" >> "$GITHUB_OUTPUT"
      - name: The harnesses the merges since then can affect
        id: harnesses
        # A failure here is judged by the next step: the run passes when every failed harness passes again at HEAD.
        continue-on-error: true
        env:
          PARITY_HOSTS: ''
          BASE_SHA: ${{ steps.base.outputs.sha }}
        run: |
          echo "Merges since ${BASE_SHA}:"
          git log --first-parent --format='  %h %s' "$BASE_SHA..HEAD"
          python3 tools/parity.py --changed "$BASE_SHA" --timeout 2400
      - name: A flake, or the merge that broke them
        if: steps.harnesses.outcome == 'failure'
        env:
          GH_TOKEN: ${{ github.token }}
          PARITY_HOSTS: ''
          BASE_SHA: ${{ steps.base.outputs.sha }}
        run: |
          rm -rf .local/parity-main-logs && cp -R .local/parity-runner/logs .local/parity-main-logs 2>/dev/null || true
          python3 tools/parity_main.py bisect "$BASE_SHA" --comment
      - name: Logs of the failed harnesses
        if: steps.harnesses.outcome == 'failure'
        uses: actions/upload-artifact@v4
        with:
          name: parity-main-logs
          path: .local/parity-main-logs/
          if-no-files-found: ignore
          retention-days: 7