ci(mutation): run mutation testing on main through systemfsoftware's reusable workflow

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
   sfs-deps:
     name: systemfsoftware tarballs from the flake
     runs-on: ubuntu-latest
-    timeout-minutes: 10
+    timeout-minutes: 60
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: cachix/install-nix-action@13d8dd58da0234aa297dedd986986ccb8e7f3e24 # v31.11.1
@@ -47,10 +47,10 @@ jobs:
       actions: read
     uses: systemfsoftware/systemfsoftware/.github/workflows/reusable-checks.yml@732f66a0c85819b2005f9e0930a595bc4de91ee1
     with:
-      lanes: '[{"id": "lint", "name": "lint", "timeout-minutes": 10, "run": "pnpm lint"}, {"id": "typecheck", "name": "typecheck", "timeout-minutes": 10, "run": "pnpm typecheck"}, {"id": "build", "name": "build · attw", "timeout-minutes": 10, "run": "pnpm build && pnpm --filter @systemfsoftware/api-extractor attw"}]'
-      timeout-minutes: 10
+      lanes: '[{"id": "lint", "name": "lint", "timeout-minutes": 60, "run": "pnpm lint"}, {"id": "typecheck", "name": "typecheck", "timeout-minutes": 60, "run": "pnpm typecheck"}, {"id": "build", "name": "build · attw", "timeout-minutes": 60, "run": "pnpm build && pnpm --filter @systemfsoftware/api-extractor attw"}]'
+      timeout-minutes: 60
       max-seconds: 600
-      plan-timeout-minutes: 10
+      plan-timeout-minutes: 60
 
   host-bytes:
     name: Output bytes on ${{ matrix.arch }}
@@ -63,7 +63,7 @@ jobs:
           - arch: arm64
             runner: ubuntu-24.04-arm
     runs-on: ${{ matrix.runner }}
-    timeout-minutes: 10
+    timeout-minutes: 60
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
@@ -88,7 +88,7 @@ jobs:
     name: Same bytes on every host
     needs: host-bytes
     runs-on: ubuntu-latest
-    timeout-minutes: 5
+    timeout-minutes: 60
     steps:
       - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:

.github/workflows/mutation.yml

@@ -0,0 +1,31 @@
+# Cost: at least 25 runner-min/day for the one full run a night; a push to main starts no
+# run, so the 7-day merge rate (5 first-parent commits on main, 2026-10-06T06:00Z to
+# 2026-10-13T06:00Z) does not price it. Each manual dispatch costs one more such run.
+# Per run: 1,469 job-seconds over six jobs, run 38120830653, a floor: Stryker was killed
+# 960 s in with 63 of 1354 mutants done. The proof run's measurement replaces it.
+name: Mutation
+
+on:
+  schedule:
+    - cron: "47 14 * * *"
+  workflow_dispatch:
+
+concurrency:
+  group: mutation-${{ github.run_id }}
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+
+jobs:
+  mutation:
+    if: github.ref == 'refs/heads/main'
+    permissions:
+      contents: read
+      actions: write
+    uses: systemfsoftware/systemfsoftware/.github/workflows/reusable-mutation.yml@02bf9653b1ca2b0a2951baf2743bb3f70d19fc77
+    with:
+      target-seconds: 480
+      max-jobs: 20
+      timeout-minutes: 60
+      report-timeout-minutes: 60

.github/workflows/release.yml

@@ -28,7 +28,7 @@ jobs:
     name: no release off main, so the run concludes success, not skipped
     if: github.ref != 'refs/heads/main'
     runs-on: ubuntu-latest
-    timeout-minutes: 1
+    timeout-minutes: 60
     permissions: {}
     steps:
       - run: echo "Release writes only from refs/heads/main; $GITHUB_REF runs nothing."

AGENTS.md

@@ -21,7 +21,9 @@ verdict. Requirements and decisions: `docs/plans/2026-10-10-1146-feat-effect-api
 - The family lint preset is never overridden locally: no rule set to `off`, ignore
   pattern or disable comment (gate: review of `oxlint.config.ts` and source diffs). A rule
   that forbids correct code is reported upstream as a preset defect.
-- Mutation testing runs on `main` only.
+- Mutation testing runs in CI only, on `main`: nightly, and by manual dispatch on `main`.
+  Never per push or on pull requests (gate: `.github/workflows/mutation.yml`'s triggers
+  and its `refs/heads/main` job condition).
 
 ## Commands
 

README.md

@@ -19,7 +19,7 @@ The design and its requirements live in
 | systemfsoftware and stryker-js-effect packages from the flake (`.sfs-deps`) | in this repository |
 | Lint, typecheck, build and test on systemfsoftware's reusable checks; tsdown, vitest and lint presets | in this repository |
 | Releases: changesets and GitHub Releases through pnpm-release-management | in this repository |
-| Mutation testing on `main` | waits on systemfsoftware's reusable mutation workflow (#710) |
+| Mutation testing on `main` | in this repository: systemfsoftware's reusable mutation workflow at `02bf965` (#735), nightly and by manual dispatch on `main` |
 
 ## The verdict