Complete regional raster exploration

docs/API_CONTRACTS.md

@@ -257,6 +257,17 @@ in degrees. Area geometry is an exact mask, not only a bounding box.
 The response always lists `water_depth_m` and `water_volume_m3` under
 `unsupported_metrics`. Drainage is not calculated by this endpoint.
 
+### POST `/api/v1/projects/{project_id}/datasets/raster/terrain/select`
+
+Runs the same exact terrain calculation over every persisted municipal DHMV
+partition intersecting one bounded EPSG:4326 rectangle. The request adds the
+governed `product_key` (`dtm_1m` or `dsm_1m`) to the ordinary selection bbox
+and optional Area id. The backend mosaics only the intersecting windows in
+EPSG:31370, enforces the existing 12-million-cell limit and calculates global
+cell statistics. The canonical response includes `dataset_ids` and
+`partition_count`; percentiles are calculated from the combined cells and are
+not averages of municipal summaries.
+
 ### GET `/api/v1/projects/{project_id}/datasets/{dataset_id}/raster/terrain/image`
 
 Returns a browser-safe PNG colour relief for the persisted governed DHMV
@@ -316,6 +327,16 @@ it is explicitly not concurrent flood storage, permanent waterbody content,
 current water level or bathymetry. These unsupported metrics remain listed in
 the response.
 
+### POST `/api/v1/projects/{project_id}/datasets/raster/flood-hazard/select`
+
+Runs exact bounded analysis over the persisted municipal VMM partitions for
+one governed `product_key`. Only partitions intersecting the selection are
+opened, the normalized metre grids are combined at their common 5 m analysis
+resolution and the global area/depth metrics are calculated from the combined
+cells. The canonical response includes every contributing Dataset id in
+`dataset_ids` plus `partition_count`. The existing flood-volume and bathymetry
+prohibitions are unchanged.
+
 ### GET `/api/v1/projects/{project_id}/datasets/{dataset_id}/raster/flood-hazard/image`
 
 Returns a constrained transparent PNG for a persisted governed VMM flood-depth