feat: stream municipality vectors by viewport

backend/README.md

@@ -907,6 +907,11 @@ returns a canonical-envelope GeoJSON FeatureCollection. It is intended for the
 Map workspace area-extract flow and does not create derived datasets or export
 records by itself.
 
+The same bounded endpoint is the canonical large-layer map delivery path. The
+frontend requests at most 1,000 features for the current viewport and surfaces
+the response `truncated` flag; the backend does not provide or imply an
+unbounded municipality-wide map response.
+
 `POST /api/v1/projects/{project_id}/datasets/{dataset_id}/vector/select/derive`
 uses the same persisted `vector_features` selection but writes the result as a
 new derived vector dataset. The created dataset uses

backend/tests/test_sprint121_real_data_detection_qa_smoke.py

@@ -14,10 +14,13 @@ def test_real_data_detection_qa_smoke_requires_operator_inputs_and_checks_full_c
     assert "bash -n scripts/verify_real_data_detection_qa_workflow.sh" in readiness
     assert "REAL_RASTER_PATH" in script
     assert "REAL_REFERENCE_VECTOR_PATH" in script
+    assert "REAL_PROJECT_ID" in script
+    assert "REAL_DATASET_NAME_PREFIX" in script
     assert "usage()" in script
     assert "/api/v1/projects" in script
     assert "/datasets/upload" in script
     assert "dataset_role=reference" in script
+    assert 'area_upload_args=(-F "area_id=${area_id}")' in script
     assert "reference_layer_name=buildings" in script
     assert "/raster/inspect" in script
     assert "/raster/tile" in script

backend/tests/test_sprint182_viewport_vector_delivery.py

@@ -0,0 +1,48 @@
+from pathlib import Path
+
+import pytest
+from pydantic import ValidationError
+
+from app.schemas.operations import VectorSelectionBBox, VectorSelectionRequest
+
+
+ROOT = Path(__file__).resolve().parents[2]
+
+
+def test_vector_selection_contract_keeps_an_explicit_bounded_limit() -> None:
+    bbox = VectorSelectionBBox(min_x=5.03, min_y=51.15, max_x=5.25, max_y=51.33)
+
+    request = VectorSelectionRequest(bbox=bbox, limit=1000)
+
+    assert request.limit == 1000
+    with pytest.raises(ValidationError):
+        VectorSelectionRequest(bbox=bbox, limit=1001)
+
+
+def test_large_vector_delivery_uses_existing_postgis_bbox_contract() -> None:
+    config = (ROOT / "frontend" / "src" / "config" / "vectorDelivery.ts").read_text(encoding="utf-8")
+    viewport_hook = (ROOT / "frontend" / "src" / "hooks" / "useViewportVectorLayer.ts").read_text(encoding="utf-8")
+    dataset_hook = (ROOT / "frontend" / "src" / "hooks" / "useDatasetWorkflow.ts").read_text(encoding="utf-8")
+
+    assert "VECTOR_VIEWPORT_FEATURE_THRESHOLD = 5_000" in config
+    assert "VECTOR_VIEWPORT_MIN_ZOOM = 14" in config
+    assert "VECTOR_VIEWPORT_FEATURE_LIMIT = 1_000" in config
+    assert "datasetsApi.selectVectorFeatures" in viewport_hook
+    assert "response.truncated" in viewport_hook
+    assert "requestSequence" in viewport_hook
+    assert "summary.feature_count ?? dataset.feature_count" in dataset_hook
+    assert "datasetsApi.getContent" in dataset_hook
+
+
+def test_map_reports_viewport_and_does_not_refit_each_slice() -> None:
+    app = (ROOT / "frontend" / "src" / "App.tsx").read_text(encoding="utf-8")
+    geo_map = (ROOT / "frontend" / "src" / "components" / "GeoMap.tsx").read_text(encoding="utf-8")
+    workspace = (ROOT / "frontend" / "src" / "components" / "map" / "MapWorkspace.tsx").read_text(encoding="utf-8")
+
+    assert "useViewportVectorLayer" in app
+    assert "fitMapDataOnChange={!viewportVectorLayerActive}" in app
+    assert "map.on('moveend', emitViewport)" in geo_map
+    assert "fitDataOnChange" in geo_map
+    assert "onViewportChange" in geo_map
+    assert "Zoom in to level" in (ROOT / "frontend" / "src" / "hooks" / "useViewportVectorLayer.ts").read_text(encoding="utf-8")
+    assert "viewport-vector-status" in workspace