Persist QA feature evidence

docs/API_CONTRACTS.md

@@ -988,6 +988,14 @@ Request:
 
 Response is wrapped in the job envelope. On success, `result_json` includes precision, recall, F1, mean IoU, false positives, false negatives and `quality_check_id`.
 
+Sprint 111 also includes feature-level evidence arrays for map/review handoff:
+
+- `match_evidence`: matched candidate/reference feature ids with IoU.
+- `false_positive_evidence`: unmatched candidate feature ids.
+- `false_negative_evidence`: unmatched reference feature ids.
+
+These arrays are derived from the same persisted/source geometries used for IoU matching. They are not separate QA records yet; they are persisted inside `quality_checks.findings_json`.
+
 Sprint 7A persists the QA/QC result as:
 
 - `jobs`: execution state.
@@ -1016,7 +1024,28 @@ Response:
       "status": "ok",
       "score": 0.5,
       "parameters_json": {},
-      "findings_json": {},
+      "findings_json": {
+        "matches": 1,
+        "false_positives": 1,
+        "false_negatives": 1,
+        "match_evidence": [
+          {
+            "candidate_feature_id": "candidate-feature-id",
+            "reference_feature_id": "reference-feature-id",
+            "iou": 0.83
+          }
+        ],
+        "false_positive_evidence": [
+          {
+            "candidate_feature_id": "candidate-extra-id"
+          }
+        ],
+        "false_negative_evidence": [
+          {
+            "reference_feature_id": "reference-missing-id"
+          }
+        ]
+      },
       "metrics": [
         {
           "metric_key": "precision",

docs/CODEX_EXECUTION_LOG.md

@@ -1,3 +1,37 @@
+## Sprint 111 QA feature evidence persistence (2026-06-25)
+
+Changed:
+- Added feature-level evidence extraction to the shared QA IoU matcher.
+- Dataset QA now returns and persists `match_evidence`, `false_positive_evidence` and `false_negative_evidence`.
+- Detection QA and segmentation QA now use the same evidence-aware matcher and persist the same evidence keys in `quality_checks.findings_json`.
+- Extended the QA/QC drilldown with compact matched, false-positive and false-negative feature id lists before the raw findings JSON.
+- Updated `docs/API_CONTRACTS.md`, `frontend/README.md`, `CHANGELOG.md` and `docs/TODO.md`.
+- Added/extended regression coverage in `backend/tests/test_qa_service.py`, `backend/tests/test_sprint7a_persistence_foundation.py` and `backend/tests/test_sprint111_qa_feature_evidence.py`.
+
+Validation:
+- RED: `python -m pytest backend\tests\test_qa_service.py -q` failed before implementation because `QaProviderComparisonResult` had no `match_evidence`.
+- RED: `python -m pytest backend\tests\test_sprint111_qa_feature_evidence.py -q` failed before docs were updated because `docs/API_CONTRACTS.md` did not document the evidence keys.
+- `python -m pytest backend\tests\test_qa_service.py -q` passed: 3 tests.
+- `python -m pytest backend\tests\test_sprint8c_detection_visualization_qa.py backend\tests\test_sprint9_segmentation_foundation.py -q` passed: 18 tests.
+- `python -m pytest backend\tests\test_sprint111_qa_feature_evidence.py -q` passed: 2 tests.
+- `python -m pytest backend\tests\test_qa_service.py backend\tests\test_sprint7a_persistence_foundation.py -q` passed: 10 tests.
+- `python -m compileall backend/app` passed.
+- `cd backend && python -m pytest -q` passed: 352 tests.
+- `cd frontend && npm run typecheck` passed.
+- `cd frontend && npm run build` passed.
+- `cd backend && python -m alembic heads` passed: `202606120900 (head)`.
+- `cd backend && python -m alembic upgrade head --sql` passed.
+- `bash -n scripts/live_migration_smoke.sh` passed.
+- `bash scripts/run_readiness_check.sh` passed.
+
+Limitations:
+- Feature-level evidence is persisted as ids/IoU metadata in `quality_checks.findings_json`; no `quality_check_items` table or first-class evidence geometry table was introduced.
+- Evidence map overlays can now be built from persisted ids, but overlay generation remains future work.
+- No migration, provider fetching, AI dependency, real model behavior or new product domain was added.
+
+Next recommended pass:
+- Add QA evidence overlay generation by resolving persisted evidence ids back to candidate/reference geometries and rendering false positives/false negatives as MapLibre layers.
+
 ## Sprint 110 Map QA evidence drilldown (2026-06-25)
 
 Changed:

docs/TODO.md

@@ -377,3 +377,4 @@ This file now starts with the current implementation status. Older preparation/b
 - [x] Persist map area selections as reusable derived vector datasets indexed into `vector_features`.
 - [x] Add Map workspace QA/QC shortcut for saved derived selection datasets.
 - [x] Add Map workspace QA/QC evidence drilldown handoff for saved selection comparisons.
+- [x] Persist QA/QC feature-level evidence for matches, false positives and false negatives.