Persist QA feature evidence

backend/tests/test_qa_service.py

@@ -22,23 +22,30 @@ class FakeSession:
         return None
 
 
+def _feature(feature_id: str, coordinates: list[list[list[float]]]) -> dict:
+    return {
+        "type": "Feature",
+        "id": feature_id,
+        "properties": {"source_feature_id": feature_id},
+        "geometry": {
+            "type": "Polygon",
+            "coordinates": coordinates,
+        },
+    }
+
+
 def _write_dataset(path: Path, coordinates: list[list[list[float]]]) -> None:
     payload = {
         "type": "FeatureCollection",
-        "features": [
-            {
-                "type": "Feature",
-                "properties": {},
-                "geometry": {
-                    "type": "Polygon",
-                    "coordinates": coordinates,
-                },
-            },
-        ],
+        "features": [_feature("feature-1", coordinates)],
     }
     path.write_text(json.dumps(payload), encoding="utf-8")
 
 
+def _write_features(path: Path, features: list[dict]) -> None:
+    path.write_text(json.dumps({"type": "FeatureCollection", "features": features}), encoding="utf-8")
+
+
 def test_qa_compare_candidate_with_reference_returns_metrics(tmp_path) -> None:
     project_id = uuid4()
     candidate_id = uuid4()
@@ -87,6 +94,62 @@ def test_qa_compare_candidate_with_reference_returns_metrics(tmp_path) -> None:
     assert result.f1_score == 1.0
 
 
+def test_qa_compare_candidate_with_reference_returns_feature_level_evidence(tmp_path) -> None:
+    project_id = uuid4()
+    candidate_id = uuid4()
+    reference_id = uuid4()
+    candidate_path = tmp_path / "candidate.geojson"
+    reference_path = tmp_path / "reference.geojson"
+    matched_candidate = [[[4.0, 51.0], [4.1, 51.0], [4.1, 51.1], [4.0, 51.1], [4.0, 51.0]]]
+    matched_reference = [[[4.0, 51.0], [4.1, 51.0], [4.1, 51.1], [4.0, 51.1], [4.0, 51.0]]]
+    false_positive = [[[4.5, 51.5], [4.6, 51.5], [4.6, 51.6], [4.5, 51.6], [4.5, 51.5]]]
+    false_negative = [[[4.8, 51.8], [4.9, 51.8], [4.9, 51.9], [4.8, 51.9], [4.8, 51.8]]]
+    _write_features(candidate_path, [_feature("candidate-match", matched_candidate), _feature("candidate-extra", false_positive)])
+    _write_features(reference_path, [_feature("reference-match", matched_reference), _feature("reference-missing", false_negative)])
+
+    candidate = Dataset(
+        id=candidate_id,
+        project_id=project_id,
+        name="candidate.geojson",
+        dataset_type="vector",
+        source="test",
+        storage_path=str(candidate_path),
+        crs="EPSG:4326",
+        metadata_json={"crs_assumed": False},
+    )
+    reference = Dataset(
+        id=reference_id,
+        project_id=project_id,
+        name="reference.geojson",
+        dataset_type="vector",
+        source="test",
+        storage_path=str(reference_path),
+        crs="EPSG:4326",
+        metadata_json={"crs_assumed": False},
+    )
+
+    result = QaService.compare_candidate_with_reference(
+        db=FakeSession([candidate, reference]),
+        project_id=project_id,
+        candidate_dataset_id=candidate_id,
+        reference_dataset_id=reference_id,
+        iou_threshold=0.5,
+    )
+
+    assert result.matches == 1
+    assert result.false_positives == 1
+    assert result.false_negatives == 1
+    assert result.match_evidence == [
+        {
+            "candidate_feature_id": "candidate-match",
+            "reference_feature_id": "reference-match",
+            "iou": 1.0,
+        }
+    ]
+    assert result.false_positive_evidence == [{"candidate_feature_id": "candidate-extra"}]
+    assert result.false_negative_evidence == [{"reference_feature_id": "reference-missing"}]
+
+
 def test_dataset_reference_metadata_migration_declares_required_columns() -> None:
     migration_path = Path(__file__).parents[1] / "alembic" / "versions" / "202606120001_add_dataset_reference_metadata.py"
     migration_text = migration_path.read_text(encoding="utf-8")