mutation-affected.yml

name: Mutation Affected

# PR-side half of the decision-kernel mutation lane (issue #1415).
#
# Graduation, not a flag day: this job runs on every PR that touches a kernel
# module, but `scripts/mutation/run.ts` only exits non-zero once the committed
# baseline reports `gating: true` — earned by two consecutive stable weekly
# sweeps (mutation-weekly.yml). Until then it is a report with the same numbers,
# so the gate's first failing day is not also its first running day.
#
# Cost control: before graduation an affected run is a report nobody acts on, so
# `select` returns an empty matrix and no mutants run — except when the diff
# touches the lane's own tooling, the one case where a pre-graduation run buys
# something (the gate has to be proven before it can bite).
#
# Scope is the AFFECTED modules only, and affectedness is DERIVED from the import
# graph (scripts/mutation/ownership.ts): a kernel source, or any test that reaches
# one. Reaching a kernel is a superset of killing its mutants, so the `select` job
# frequently returns several modules — sharded like the weekly sweep so the PR's
# wall clock is one module, not their sum. The weekly run stays the full sweep.

on:
  pull_request:
    paths:
      # Kernel sources, every src/package test (ownership is derived, so any
      # test may own a kernel — `select` decides, not this filter), and the
      # lane's own tooling. scripts/mutation/workflow.test.ts asserts this
      # covers the registry.
      - 'packages/kernel/src/errors.ts'
      - 'src/daemon/ref-frame.ts'
      - 'src/commands/interaction/runtime/settle.ts'
      - 'src/utils/scroll-edge-state.ts'
      - 'packages/selectors/src/**'
      - 'packages/ad-script/src/internal/target-annotation-serde.ts'
      - 'src/snapshot/snapshot-occlusion.ts'
      - 'src/**/*.test.ts'
      - 'packages/*/src/**/*.test.ts'
      - 'scripts/mutation/**'
      - 'scripts/lib/**'
      - 'stryker.config.json'
      - 'mutation-baselines/**'
      - '.github/workflows/mutation-affected.yml'

permissions:
  contents: read

concurrency:
  group: ci-${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  select:
    name: Select affected kernels
    runs-on: ubuntu-latest
    timeout-minutes: 10
    outputs:
      modules: ${{ steps.select.outputs.result }}
    steps:
      - name: Checkout
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          fetch-depth: 0

      - name: Setup toolchain
        uses: ./.github/actions/setup-node-pnpm

      - name: Ratchet self-test
        uses: ./.github/actions/run-gate
        with: { gate: mutation-model }

      - id: select
        name: Derive the affected shard matrix
        uses: ./.github/actions/run-gate
        with:
          gate: mutation-affected
          args: |
            --list-affected
            --base
            origin/${{ github.event.pull_request.base.ref }}

      # The self-test and the derivation run before any mutant, so a failure here
      # would leave the lane with no envelope at all (#1430).
      - name: Record a failed lane envelope
        if: failure()
        run: |
          pnpm gate mutation --affected --fail-envelope \
            "affected selection failed before any mutant ran (run ${{ github.run_id }})" || true

      - name: Upload selection envelope
        if: failure()
        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
        with:
          name: mutation-affected-select
          path: .tmp/mutation/lane-envelope.json
          if-no-files-found: warn

  mutants:
    name: Mutants (${{ matrix.name }})
    needs: select
    if: needs.select.outputs.modules != '[]'
    runs-on: ubuntu-latest
    timeout-minutes: 30
    strategy:
      fail-fast: false
      matrix:
        include: ${{ fromJSON(needs.select.outputs.modules) }}
    steps:
      - name: Checkout
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2

      - name: Setup toolchain
        uses: ./.github/actions/setup-node-pnpm

      - name: Run mutants for ${{ matrix.name }}
        uses: ./.github/actions/run-gate
        with:
          gate: mutation
          args: |
            --modules
            ${{ matrix.module }}
            ${{ matrix.shard && '--shard' || '' }}
            ${{ matrix.shard || '' }}

      - name: Record a failed shard envelope
        if: failure()
        run: |
          pnpm gate mutation --affected --modules ${{ matrix.module }} --fail-envelope \
            "shard ${{ matrix.name }} failed before producing a report (run ${{ github.run_id }})" || true

      - name: Upload shard report
        if: always()
        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
        with:
          name: mutation-affected-shard-${{ matrix.name }}
          path: |
            .tmp/mutation/mutation.json
            .tmp/mutation/mutation.html
            .tmp/mutation/lane-envelope.json
          if-no-files-found: warn

  ratchet:
    name: Affected decision-kernel mutants
    needs: [select, mutants]
    if: always() && needs.select.result == 'success'
    runs-on: ubuntu-latest
    timeout-minutes: 15
    steps:
      - name: Checkout
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          fetch-depth: 0

      - name: Setup toolchain
        uses: ./.github/actions/setup-node-pnpm

      - name: Download shard reports
        if: needs.select.outputs.modules != '[]'
        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
        with:
          pattern: mutation-affected-shard-*
          path: .tmp/mutation/shards

      # No shards means no affected kernel: run.ts reports "nothing to mutate"
      # and still writes the envelope, so the lane is never silently absent.
      - name: Ratchet the affected modules
        run: |
          if [ -d .tmp/mutation/shards ]; then
            expected=$(echo '${{ needs.select.outputs.modules }}' | jq length)
            pnpm gate mutation-check --report-dir .tmp/mutation/shards --affected \
              --expect-shards "$expected" \
              --base "origin/${{ github.event.pull_request.base.ref }}"
          else
            pnpm gate mutation-affected --base "origin/${{ github.event.pull_request.base.ref }}"
          fi

      - name: Record a failed lane envelope
        if: failure()
        run: |
          pnpm gate mutation --affected --fail-envelope \
            "affected ratchet failed before producing a verdict (run ${{ github.run_id }})" || true

      - name: Upload mutation report
        if: always()
        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
        with:
          name: mutation-affected
          path: |
            .tmp/mutation/shards
            .tmp/mutation/lane-envelope.json
          if-no-files-found: ignore