REAL code-level cause (prod-confirmed, 2 parcels: "Geometry type (Polygon) does
not match column type (MultiPolygon)") of single-contour parcels stuck "fetching"
— complements migrations 129/130 (which fixed the cad_parcels NOT NULL chain).
F1: _save_parcel/_save_quarter now ST_Multi() the geom so single-contour Polygons
fit the MultiPolygon columns (migr 93/58), mirroring the bulk_harvest paths.
F2: _save_building rewritten to the wide cad_buildings schema (migr 92):
quarter_cad_number (was quarter_cad_num → UndefinedColumn), _safe_int(floors)
(range strings → NULL), source='nspd' NOT NULL.
F3: upsert_features wraps each feature in begin_nested() SAVEPOINT so one bad
feature no longer aborts the whole quarter snapshot (backend.md rule; mirrors
grid-walk). New tests/workers/test_nspd_geo.py + savepoint tests. 89 passed.
