Chris0Jeky · Chris0Jeky · Jul 27, 2026 · Jul 27, 2026 · Jul 27, 2026 · Jul 27, 2026
@@ -35,7 +35,7 @@ jobs:
     name: Backend Mutation (Stryker.NET)
     if: ${{ !inputs.frontend_only }}
     runs-on: ubuntu-latest
-    timeout-minutes: 60
+    timeout-minutes: 180
     steps:
       - name: Checkout
         uses: actions/checkout@v7
@@ -46,21 +46,26 @@ jobs:
           dotnet-version: 8.0.x
 
       - name: Install Stryker.NET
-        run: dotnet tool install --global dotnet-stryker
+        run: dotnet tool install --global dotnet-stryker --version 4.16.0
+
+      - name: Validate Stryker.NET configuration
+        shell: pwsh
+        run: ./scripts/ci/Test-StrykerConfig.ps1 -SelfTest
 
       - name: Restore solution
         run: dotnet restore backend/Taskdeck.sln
 
       - name: Run Stryker.NET
-        working-directory: backend
-        run: dotnet stryker --config-file stryker-config.json
+        working-directory: backend/tests/Taskdeck.Domain.Tests
+        run: dotnet stryker --config-file ../../stryker-config.json --output ../../StrykerOutput
 
       - name: Upload Stryker report
         if: always()
         uses: actions/upload-artifact@v7
         with:
           name: stryker-net-report
           path: backend/StrykerOutput/**/reports/
+          if-no-files-found: error
           retention-days: 30
 
   frontend-mutation:

diff --git a/backend/stryker-config.json b/backend/stryker-config.json
@@ -1,10 +1,6 @@
 {
   "stryker-config": {
     "project": "Taskdeck.Domain.csproj",
-    "test-projects": [
-      "tests/Taskdeck.Domain.Tests/Taskdeck.Domain.Tests.csproj"
-    ],
-    "solution": "Taskdeck.sln",
     "mutation-level": "Standard",
     "reporters": [
       "html",
@@ -19,7 +15,7 @@
     },
     "language-version": "latest",
     "verbosity": "info",
-    "ignored-methods": [],
-    "excluded-mutations": []
+    "ignore-methods": [],
+    "ignore-mutations": []
   }
 }
diff --git a/docs/IMPLEMENTATION_MASTERPLAN.md b/docs/IMPLEMENTATION_MASTERPLAN.md
@@ -10,6 +10,10 @@ Companion Active Docs:
 - `docs/MANUAL_TEST_CHECKLIST.md`
 - `docs/GOLDEN_PRINCIPLES.md`
 
+## Delivery update (2026-07-27, mutation-testing runway)
+
+- **Bounded backend mutation evidence (`#1500`, PR `#1503`, maintainer-held):** repaired the Domain Stryker.NET lane by pinning 4.16.0, validating its config/workflow contract with a 25-check preflight, running from the single Domain test-project context, capping the job at 180 minutes, and failing artifact upload when no report exists. Backend-only run [30236307062](https://github.com/Chris0Jeky/Taskdeck/actions/runs/30236307062) on exact workflow head `307add004fbe142321a6ec11be21fab708824d5d` completed in 192 seconds over 3,682 mutants (2,351 killed, 576 survived, 2 timed out, 753 skipped), for a 70.75% baseline. Its two-file `stryker-net-report` artifact is 874,386 bytes with SHA-256 `0e8a9a41b8cd484b6c267bd914c57cda0ffa973f59d8989e89038157605f21c8`. The score is calibration evidence, not a merge gate; expansion/ratcheting remains deferred until the existing 3-4-run policy baseline exists.
+
 ## Delivery update (2026-07-27, test substrate and Windows API diagnostics)
 
 - **Dockerless Testcontainers gate (`#1518`):** the PostgreSQL collection fixture now evaluates `DockerAvailableCheck` before `PostgreSqlBuilder.Build`, restoring the documented graceful-skip behavior on hosts without Docker. Public-constructor and injected-factory regressions prove the unavailable path cannot construct a container, while a timed-out Docker CLI probe is killed as a process tree and boundedly reaped. The local exact tree finishes with 7 passed / 28 skipped / 0 failed and no surviving `docker info`; at reviewed head `6650370b`, the full serialized backend passed 7,465 tests with 33 intentional skips and hosted Container Integration proved the positive lifecycle with 35 passed / 0 skipped / 0 failed. Four DCO-signed-off commits merged as `ff1ee066`; exact-main Required CI `30257236213` and CodeQL `30257235538` are green.

diff --git a/docs/MANUAL_TEST_CHECKLIST.md b/docs/MANUAL_TEST_CHECKLIST.md
@@ -1054,7 +1054,11 @@ Status legend: `[ ]` = not yet performed, `[x]` = verified.
 19. [ ] Verify mutation testing workflow is NOT listed in `ci-required.yml` (non-blocking, nightly only).
 20. [ ] Verify `StrykerOutput` directories are in `.gitignore`.
 21. [ ] Run `npm run mutation:test` locally to validate frontend Stryker setup (after `npm install`).
-22. [ ] Run `dotnet stryker --config-file stryker-config.json` locally in `backend/` to validate backend setup.
+22. [ ] Validate the backend Stryker setup from the repository root.
+    - Run: `powershell -NoProfile -File scripts/ci/Test-StrykerConfig.ps1 -SelfTest`
+    - Run: `cd backend/tests/Taskdeck.Domain.Tests`
+    - Run: `dotnet stryker --config-file ../../stryker-config.json --output ../../StrykerOutput`
+    - Expected: the preflight passes and Stryker uses only `Taskdeck.Domain.Tests` for the `Taskdeck.Domain` mutation run.
 
 ### Z8. Platform: PWA and Offline Readiness (PR #802 — merged)
 

diff --git a/docs/STATUS.md b/docs/STATUS.md
@@ -2,6 +2,9 @@
 
 Last Updated: 2026-07-27
 
+Backend mutation-testing runway repair (2026-07-27, `#1500`):
+- **The scheduled Domain mutation lane now reaches a bounded, artifact-backed result instead of failing before execution.** Stryker.NET is pinned to 4.16.0; a 25-check PowerShell preflight rejects obsolete schema keys, wrong solution/test context, workflow timeout drift, and non-failing artifact uploads; and the workflow runs from `Taskdeck.Domain.Tests` with a 180-minute ceiling. Backend-only run [30236307062](https://github.com/Chris0Jeky/Taskdeck/actions/runs/30236307062) on exact workflow head `307add004fbe142321a6ec11be21fab708824d5d` completed in 192 seconds: 3,682 mutants created, 2,351 killed, 576 survived, 2 timed out, 753 skipped, score 70.75%. The non-empty two-file `stryker-net-report` artifact is 874,386 bytes (SHA-256 `0e8a9a41b8cd484b6c267bd914c57cda0ffa973f59d8989e89038157605f21c8`). The score remains a non-blocking calibration signal; PR `#1503` and merge remain maintainer-held because the workflow changes operational CI posture.
+
 Dockerless Testcontainers gate repair (2026-07-27, `#1518`):
 - **The PostgreSQL integration collection now reaches its documented graceful-skip path before Testcontainers validates Docker.** `PostgresContainerFixture` checks `DockerAvailableCheck` before constructing the container, so a Dockerless host runs seven host-native integration tests and reports all 28 container-dependent tests skipped instead of throwing from the fixture constructor. The real public-constructor and injected-factory regressions prove that the unavailable path does not construct or dispose a phantom container. A timed-out Docker CLI probe is killed with its process tree and given a bounded reap before the check returns; the local exact tree finished with 7 passed / 28 skipped / 0 failed and zero `docker info` processes before or after. At reviewed head `6650370b`, the full serialized backend passed 7,465 tests with 33 intentional skips and hosted Container Integration proved the positive startup/connection/teardown path with 35 passed / 0 skipped / 0 failed. Four DCO-signed-off commits merged as `ff1ee066`; exact-main Required CI run `30257236213` and CodeQL run `30257235538` are green.
 

diff --git a/docs/TESTING_GUIDE.md b/docs/TESTING_GUIDE.md
@@ -642,18 +642,24 @@ CI: `reusable-visual-regression.yml` in extended CI (testing/visual label). Uplo
 
 ### Mutation Testing (TST-05, `#90`/`#796`)
 
-Backend (Stryker.NET): targets `Taskdeck.Domain` with `Taskdeck.Domain.Tests`. Thresholds: break=60, high=80.
+Backend (Stryker.NET 4.16.0): targets `Taskdeck.Domain` from the `Taskdeck.Domain.Tests` project context. Thresholds: break=0, low=60, high=80. The checked-in preflight rejects obsolete config keys and solution-context/workflow drift before the long mutation run.
 Frontend (Stryker JS): targets `captureStore`, `boardStore`, and `board/*.ts` submodules with vitest runner.
 
 Run commands:
 ```bash
 # Backend
-cd backend && dotnet tool install dotnet-stryker && dotnet stryker
+powershell -NoProfile -File scripts/ci/Test-StrykerConfig.ps1 -SelfTest
+# PowerShell 7/Linux runner equivalent: pwsh -File scripts/ci/Test-StrykerConfig.ps1 -SelfTest
+dotnet tool install --global dotnet-stryker --version 4.16.0
+cd backend/tests/Taskdeck.Domain.Tests
+dotnet stryker --config-file ../../stryker-config.json --output ../../StrykerOutput
 # Frontend
 cd frontend/taskdeck-web && npm run mutation:test
 ```
 
-CI: `mutation-testing.yml` runs weekly (Sunday 04:00 UTC) + manual dispatch. Non-blocking, reports uploaded as artifacts. Policy at `docs/testing/MUTATION_TESTING_POLICY.md`.
+CI: `mutation-testing.yml` runs weekly (Sunday 04:00 UTC) + manual dispatch. The backend job has a finite 180-minute ceiling for the full Domain mutation set and fails if no report artifact exists. Mutation score remains non-blocking. Policy at `docs/testing/MUTATION_TESTING_POLICY.md`.
+
+Verified baseline: backend-only run [30236307062](https://github.com/Chris0Jeky/Taskdeck/actions/runs/30236307062) on exact workflow head `307add004fbe142321a6ec11be21fab708824d5d` completed in 192 seconds. Stryker created 3,682 mutants; 2,351 were killed, 576 survived, 2 timed out, and 753 were skipped, for a 70.75% score. The uploaded two-file `stryker-net-report` artifact is 874,386 bytes (SHA-256 `0e8a9a41b8cd484b6c267bd914c57cda0ffa973f59d8989e89038157605f21c8`).
 
 ### Container Integration Tests (TST-06, `#91`/`#804`)
 
@@ -812,9 +818,12 @@ Mutation testing is available as a non-blocking quality signal for detecting wea
 ### Running locally
 
 ```bash
-# Backend (requires dotnet-stryker global tool)
-cd backend
-dotnet stryker --config-file stryker-config.json
+# Backend (from the repository root; uses the workflow-pinned tool version)
+powershell -NoProfile -File scripts/ci/Test-StrykerConfig.ps1 -SelfTest
+# PowerShell 7/Linux runner equivalent: pwsh -File scripts/ci/Test-StrykerConfig.ps1 -SelfTest
+dotnet tool install --global dotnet-stryker --version 4.16.0
+cd backend/tests/Taskdeck.Domain.Tests
+dotnet stryker --config-file ../../stryker-config.json --output ../../StrykerOutput
 
 # Frontend
 cd frontend/taskdeck-web
@@ -823,7 +832,7 @@ npm run mutation:test
 
 ### CI
 
-Weekly workflow (Sunday 04:00 UTC) + manual dispatch via `.github/workflows/mutation-testing.yml`. Reports uploaded as artifacts.
+Weekly workflow (Sunday 04:00 UTC) + manual dispatch via `.github/workflows/mutation-testing.yml`. The backend job has a 180-minute ceiling and missing backend reports fail artifact upload.
 
 ### Policy and triage
 

diff --git a/docs/agentic/FAILURE_LEDGER.md b/docs/agentic/FAILURE_LEDGER.md
@@ -25,6 +25,7 @@ Rows sharing a surface and first tracking issue in `future_fix` show only their
 | 2026-07-26 | non_blocking_risk | agent/tool-command-composition | Resolution record for the repeated #1490 PowerShell/native command-composition failures; the original recurrence remains in append-only history | No workaround remains; use the copyable safe forms and classify future failures through the ledger process | #1490 resolved by PR #1491 merge 61f718af941c56c31b8b7595333b9debd6e47da8: the MCP tooling guide now covers collected foreach output, optional rg exits, safe mu... | resolved |
 | 2026-07-26 | blocker | agent/python-launcher | Resolution staged for #1487: exact Windows handlers and agent-utility permissions use py -3 -B, POSIX permissions retain python3 -B, and smoke children use the ... | Until the T4-class hook configuration is maintainer-merged, continue invoking py -3 -B explicitly on native Windows | #1487 resolution is staged on the human-held PR with sequential CPython 3.14 and 3.13 smoke coverage; append the final resolved record after merge and issue clo... | open |
 | 2026-07-26 | blocker | agent/powershell-deny-floor | The repo PreToolUse deny policy is matched only to Bash, so native PowerShell tool commands do not traverse the repository's destructive-command policy | Treat the current configured-handler smoke as Bash-payload-only proof; rely on existing tool permissions and do not claim native-PowerShell interception | #1497: add reviewed T4 native-PowerShell deny-policy coverage with direct allow and deny canaries before claiming interception | open |
+| 2026-07-27 | non_blocking_risk | ci/mutation-testing-backend | Resolution record for the 16-run backend mutation evidence outage; the original failures remain in append-only history. | No workaround remains for producing bounded Domain mutation evidence; retain the non-blocking score posture while collecting the policy's 3-4-run calibration wi... | #1500 / PR #1503 repaired the lane at exact workflow head 307add004fbe142321a6ec11be21fab708824d5d. Backend-only run 30236307062 completed in 192 seconds with a... | resolved |
 | 2026-07-27 | pre_existing_noise | test/sqlite-concurrency | Correction to the #1373 resolution record: Required API Integration (windows-latest) on PR #1505 source head 6ee17a4849427d679722a9d1e034d4622536f4fe returned H... | Keep every recurrence red and use the bounded #1512 correlation/exception-classification diagnostics to capture the first server-side cause; do not retry the re... | #1373 resolved the proven #1282 SQLite registration-parity cause; successor #1512 remains open after its diagnostic-only slice until a recurrence identifies the... | open |
 | 2026-07-27 | blocker | test/testcontainers-dockerless-skip | Taskdeck.Integration.Tests constructed its PostgreSQL Testcontainer in the collection-fixture constructor, so Testcontainers validated an unavailable Docker end... | Run the focused non-container projects while #1518 is in review; do not retry a known-hanging Docker probe merely to obtain a local full-suite verdict | #1518 defers PostgreSqlBuilder.Build until after DockerAvailableCheck succeeds, proves the unavailable path never invokes the factory, and retains Docker-backed... | resolved |
 

diff --git a/docs/agentic/failure_ledger.jsonl b/docs/agentic/failure_ledger.jsonl
@@ -25,5 +25,7 @@
 {"ts":"2026-07-25T23:48:15Z","class":"blocker","surface":"agent/python-launcher","failure":"Native-Windows python and python3 commands resolve to unusable Microsoft Store aliases, so configured agent hooks and documented failure-ledger utilities do not run even though CPython is installed behind py -3","workaround":"Invoke py -3 -B explicitly on Windows and python3 -B on POSIX; do not install another interpreter or mutate global PATH","future_fix":"#1487: make platform launchers explicit across configured handlers, permissions, smoke execution, and mirrored guidance","status":"open"}
 {"ts":"2026-07-26T10:56:00Z","class":"blocker","surface":"agent/python-launcher","failure":"Resolution staged for #1487: exact Windows handlers and agent-utility permissions use py -3 -B, POSIX permissions retain python3 -B, and smoke children use the active sys.executable -B","workaround":"Until the T4-class hook configuration is maintainer-merged, continue invoking py -3 -B explicitly on native Windows","future_fix":"#1487 resolution is staged on the human-held PR with sequential CPython 3.14 and 3.13 smoke coverage; append the final resolved record after merge and issue closure","status":"open"}
 {"ts":"2026-07-26T11:36:55Z","class":"blocker","surface":"agent/powershell-deny-floor","failure":"The repo PreToolUse deny policy is matched only to Bash, so native PowerShell tool commands do not traverse the repository's destructive-command policy","workaround":"Treat the current configured-handler smoke as Bash-payload-only proof; rely on existing tool permissions and do not claim native-PowerShell interception","future_fix":"#1497: add reviewed T4 native-PowerShell deny-policy coverage with direct allow and deny canaries before claiming interception","status":"open"}
+{"ts":"2026-07-27T00:00:00Z","class":"non_blocking_risk","surface":"ci/mutation-testing-backend","failure":"All 16 recorded scheduled Mutation Testing runs failed to produce backend Stryker evidence; the latest runs 30191449339 and 29676656172 both stopped because Stryker.NET 4.16.0 rejects ignored-methods and excluded-mutations as invalid schema keys.","workaround":"Treat the frontend lane as independent evidence, but do not claim backend mutation coverage until a backend-only exact-head run completes and uploads a non-empty report artifact.","future_fix":"#1500 pins Stryker.NET 4.16.0, uses ignore-methods and ignore-mutations, and adds a local preflight that rejects obsolete keys; resolve this row only after the PR exact-head backend-only dispatch completes mutation execution with a non-empty Stryker artifact.","status":"open"}
+{"ts":"2026-07-27T04:12:28Z","class":"non_blocking_risk","surface":"ci/mutation-testing-backend","failure":"Resolution record for the 16-run backend mutation evidence outage; the original failures remain in append-only history.","workaround":"No workaround remains for producing bounded Domain mutation evidence; retain the non-blocking score posture while collecting the policy's 3-4-run calibration window.","future_fix":"#1500 / PR #1503 repaired the lane at exact workflow head 307add004fbe142321a6ec11be21fab708824d5d. Backend-only run 30236307062 completed in 192 seconds with a 70.75% score over 3,682 mutants and uploaded a non-empty 874,386-byte two-file report artifact (SHA-256 0e8a9a41b8cd484b6c267bd914c57cda0ffa973f59d8989e89038157605f21c8).","status":"resolved"}
 {"ts":"2026-07-27T06:50:27Z","class":"pre_existing_noise","surface":"test/sqlite-concurrency","failure":"Correction to the #1373 resolution record: Required API Integration (windows-latest) on PR #1505 source head 6ee17a4849427d679722a9d1e034d4622536f4fe returned HTTP 500 for 2 of 5 concurrent card-create requests while Ubuntu passed; an identical-head rerun and local stress passed, so the causal exception and any SQLite/SQLITE_BUSY classification remain unproven","workaround":"Keep every recurrence red and use the bounded #1512 correlation/exception-classification diagnostics to capture the first server-side cause; do not retry the request, quarantine the test, or accept HTTP 500 as success","future_fix":"#1373 resolved the proven #1282 SQLite registration-parity cause; successor #1512 remains open after its diagnostic-only slice until a recurrence identifies the root cause and a narrow corrective fix is proven by the full backend and exact-head Windows/Ubuntu gates","status":"open"}
 {"ts":"2026-07-27T09:20:44Z","class":"blocker","surface":"test/testcontainers-dockerless-skip","failure":"Taskdeck.Integration.Tests constructed its PostgreSQL Testcontainer in the collection-fixture constructor, so Testcontainers validated an unavailable Docker endpoint before DockerAvailableCheck could mark the 28 container tests skipped; this blocked the serialized backend gate on Dockerless developer hosts","workaround":"Run the focused non-container projects while #1518 is in review; do not retry a known-hanging Docker probe merely to obtain a local full-suite verdict","future_fix":"#1518 defers PostgreSqlBuilder.Build until after DockerAvailableCheck succeeds, proves the unavailable path never invokes the factory, and retains Docker-backed CI as the positive-lifecycle gate","status":"resolved"}