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",