Reject same-year post-mosaic building labels

backend/tests/test_building_label_normalization.py

@@ -134,6 +134,38 @@ def test_normalizer_rejects_features_created_after_dated_imagery(tmp_path: Path)
     assert audit["decision_counts"] == {"accepted": 1, "created_after_imagery_period": 1}
 
 
+def test_normalizer_rejects_same_year_feature_after_annual_mosaic_start(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"))
+    geometry = {
+        "type": "Polygon",
+        "coordinates": [[[4.01, 50.99], [4.02, 50.99], [4.02, 50.98], [4.01, 50.98], [4.01, 50.99]]],
+    }
+    reference_path = tmp_path / "reference.geojson"
+    reference_path.write_text(json.dumps({
+        "type": "FeatureCollection",
+        "features": [{"type": "Feature", "properties": {"BEGINDATUM": "2025-08-18"}, "geometry": geometry}],
+    }), 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="2025-01-01T00:00:00Z",
+        imagery_valid_to="2025-12-31T23:59:59Z",
+        reference_observed_at="2026-07-01T00:00:00Z",
+    )
+
+    assert normalized["features"] == []
+    assert audit["decision_counts"] == {"created_after_imagery_period": 1}
+    assert audit["imagery_feature_creation_cutoff"] == "2025-01-01T00:00:00+00:00"
+
+
 def test_normalizer_merges_only_touching_visible_roof_instances(tmp_path: Path) -> None:
     raster_path = tmp_path / "image.tif"
     with rasterio.open(