feat: stream municipality vectors by viewport

docs/CODEX_EXECUTION_LOG.md

@@ -7474,3 +7474,39 @@ Open:
   layering additional municipality-wide reference classes. Then acquire and
   tile georeferenced imagery only for an explicitly selected Mol analysis zone
   and run configured-YOLO plus QA/QC against the persisted GRB reference.
+
+# Sprint 182 - Municipality viewport delivery and bounded AI handoff
+
+## Implementation
+
+- Added `useViewportVectorLayer` with centralized feature threshold, minimum
+  zoom, response limit and debounce policy. Vector datasets above 5,000
+  features now use the existing canonical PostGIS bbox-selection endpoint from
+  zoom level 14 instead of downloading the full stored GeoJSON file.
+- Added MapLibre `moveend` viewport reporting, stale-request protection and
+  disabled automatic fit for viewport slices. AOI changes still frame the map;
+  small vectors and persisted analysis/evidence layers retain their existing
+  complete-layer fit behavior.
+- Added explicit low-zoom, loading, visible/total, truncation and error states.
+  A selected large database layer is no longer presented as an empty or missing
+  layer before the first detail request.
+- Extended the real-data detection/QA workflow with validated existing-project
+  reuse, safe distinct upload filenames and actual Area linkage for the raster
+  and matching reference vector. The workflow still consumes operator-provided
+  files and an existing local model asset; it performs no provider fetch or
+  model download.
+
+## Local validation
+
+- `python -m compileall backend/app` passed.
+- Full backend suite passed: `500` tests.
+- `npm run typecheck` and `npm run build` passed; the production build contains
+  85 transformed modules and preserves the dedicated MapLibre chunk.
+- `bash scripts/run_readiness_check.sh` passed with the 81-route API contract
+  audit, one Alembic head `202606120900`, shell syntax checks and full frontend
+  build.
+- Internal browser validation against the local frontend and live Tower API
+  selected `mol_grb_gbg_buildings.geojson`, showed the zoom-14 PostGIS delivery
+  guard, suppressed the incorrect empty-layer state and loaded an actual
+  viewport slice with `2 visible of 36,941 total features`. No browser warnings
+  or errors were recorded.