feat: provision regional Kempen context layers

docs/DATASET_STRATEGY.md

@@ -124,6 +124,28 @@ reference dataset uses `source_name=grb`, `reference_layer_name=buildings`,
 selection aggregation. Existing viewport and bbox selection APIs remain the
 only interactive delivery path.
 
+### Regional GRB context partition policy
+
+Roads, water and parcels reuse the building operator's 28 resumable source
+partitions and one-dataset-per-theme persistence model. Polygon collections
+use maximum intersection area for cross-boundary ownership; line collections
+use maximum intersection length. Exact ties use the lower NIS code. Source
+identities are collection-qualified because the water theme combines `WTZ`,
+`WLAS` and `WGR`.
+
+The user-facing datasets use `source_name=grb`, `dataset_role=reference`,
+`coverage_scope=kempen-transport-region` and respectively
+`reference_layer_name=roads`, `water` or `parcels`. They are current source
+snapshots with immutable observation dates, not temporal series inferred from
+successive operator runs. Feature counts retain source-object semantics and
+must not be relabelled as road length, water area or legal parcel counts.
+
+Only `scripts/provision_regional_grb_context.py` may fetch these bounded
+artifacts. Application startup, map requests and the public provider registry
+remain fetch-free. All combined artifacts enter PostGIS through the existing
+DatasetService/VectorFeatureService boundary and existing bbox/Area selection
+contracts.
+
 ## User-uploaded raster strategy
 V1 must support controlled local datasets because public raster access and model compatibility can be difficult.