Federate official Belgium data sources

docs/API_CONTRACTS.md

@@ -2264,13 +2264,21 @@ return an empty, honest result. No provider request occurs during analysis.
 Future provider output continues to use DatasetService and, for vectors,
 VectorFeatureService. Arbitrary service URLs, browser-side fetches, insecure
 TLS bypasses and startup downloads remain forbidden.
-## Governed official nature and soil acquisition
+## Governed regional official-vector acquisition
 
 ### GET `/api/v1/projects/{project_id}/datasets/official-vector/products`
 
 Returns the fixed official vector registry in the canonical `{ "data": ... }`
-envelope. The allowlist contains `bwk_natura2000_2025` and `dov_soil_types`;
-arbitrary collection names or URLs are never accepted.
+envelope. Every item includes its theme, geometry contract, authority,
+licence/attribution, provider-native collection, query mode and
+`coverage_zones`. The fixed allowlist contains:
+
+- Flanders: `bwk_natura2000_2025` and `dov_soil_types`;
+- Wallonia: `spw_picc_buildings`, `spw_picc_roads`,
+  `spw_picc_waterways` and `spw_picc_water_surfaces`;
+- Brussels: `urbis_buildings` and `urbis_cadastral_parcels`.
+
+Arbitrary collection names or URLs are never accepted.
 
 ### POST `/api/v1/projects/{project_id}/datasets/official-vector/acquire`
 
@@ -2293,16 +2301,29 @@ Request:
 
 The synchronous `vector.official.acquire` Job validates the metric request
 size, intersects `bbox` with the persisted Area, retrieves every bounded page,
-clips polygon geometry in EPSG:31370 and persists EPSG:4326 features through
-`DatasetService`. A repeated exact request can reuse the 24-hour cache.
-Provider errors, unstable or incomplete WFS pagination and safety-limit violations
-fail without persisting a truncated Dataset.
+clips source geometry in the provider-native metric CRS and persists
+EPSG:4326 features through `DatasetService`. A repeated exact request can
+reuse the 24-hour cache. Provider errors, unstable/incomplete pagination and
+safety-limit violations fail without persisting a truncated Dataset.
+
+Walloon and Brussels products additionally require a persisted exact regional
+coverage Area (`Wallonia` or `Brussels-Capital Region`). SPW/PICC uses stable
+`OBJECTID` ArcGIS REST paging; UrbIS uses WFS 2.0 paging ordered by
+`INSPIRE_ID`. A caller cannot make a Flemish product cover Wallonia, or merge
+different regional authorities into one Dataset.
 
 `bwk_natura2000_2025` preserves BWK `EVAL`, `EENH*`, `HAB*` and `PHAB*`
 semantics. `dov_soil_types` preserves mapped soil, texture, drainage, profile
 and substrate classes and is dated as the 1949-1971 survey period. Neither
 contract accepts a caller-supplied endpoint.
 
+PICC building footprints, road axes and hydrographic axes/surfaces retain
+their source identifiers and report source-appropriate counts, footprint/
+surface hectares or line kilometres. UrbIS building footprints and cadastral
+parcels remain separate products with their own Paradigm/FPS Finance licence
+notes. These products do not claim semantic parity with GRB and do not expose
+water volume.
+
 ## Governed Landgebruik Vlaanderen forest and agriculture
 
 The existing