Add fail-closed source class and SAM fallback filters

backend/tests/test_building_label_normalization.py

@@ -166,6 +166,32 @@ def test_normalizer_rejects_same_year_feature_after_annual_mosaic_start(tmp_path
     assert audit["imagery_feature_creation_cutoff"] == "2025-01-01T00:00:00+00:00"
 
 
+def test_normalizer_applies_provider_native_source_class_allowlist(tmp_path: Path) -> None:
+    raster_path = tmp_path / "image.tif"
+    with rasterio.open(
+        raster_path, "w", driver="GTiff", width=100, height=100, count=3,
+        dtype="uint8", crs="EPSG:4326", transform=from_origin(4.0, 51.0, 0.001, 0.001),
+    ) as dataset:
+        dataset.write(np.zeros((3, 100, 100), dtype="uint8"))
+    def feature(feature_id: str, source_type: int, left: float) -> dict:
+        return {
+            "type": "Feature", "id": feature_id, "properties": {"TYPE": source_type},
+            "geometry": {"type": "Polygon", "coordinates": [[[left, 50.99], [left + .01, 50.99], [left + .01, 50.98], [left, 50.98], [left, 50.99]]]},
+        }
+    reference_path = tmp_path / "reference.geojson"
+    reference_path.write_text(json.dumps({"type": "FeatureCollection", "features": [feature("main", 1, 4.01), feature("annex", 2, 4.03)]}), encoding="utf-8")
+
+    normalized, audit = module.normalize(
+        reference_path=reference_path, raster_path=raster_path, source_name="grb",
+        min_label_px=3, imagery_observed_at=None, reference_observed_at=None,
+        allowed_source_classes={"1"},
+    )
+
+    assert [item["id"] for item in normalized["features"]] == ["grb:main"]
+    assert audit["allowed_source_classes"] == ["1"]
+    assert audit["decision_counts"] == {"accepted": 1, "source_class_not_allowed": 1}
+
+
 def test_normalizer_merges_only_touching_visible_roof_instances(tmp_path: Path) -> None:
     raster_path = tmp_path / "image.tif"
     with rasterio.open(