Complete regional raster exploration

backend/README.md

@@ -1246,6 +1246,12 @@ and a complete failure summary. Persistence remains inside the canonical
 DHMV acquisition service and Dataset/DatasetVersion/Job flow; the operator
 does not fetch WCS bytes or write raster metadata directly.
 
+The complete live matrix contains 56 ready Datasets and 56 DatasetVersions
+across 28 Areas. On the complete Kempen Area the Map workspace presents those
+partitions as one logical DTM/DSM layer. `POST .../datasets/raster/terrain/select`
+opens only partitions intersecting the drawn rectangle and computes exact
+global cell statistics. It does not create a hidden regional mosaic.
+
 Settings: `DHMV_ENABLED`, `DHMV_WCS_URL`, `DHMV_RESOLUTION_M`,
 `DHMV_MIN_SIDE_M`, `DHMV_MAX_SIDE_M`, `DHMV_MAX_PIXELS`,
 `DHMV_TIMEOUT_SECONDS` and `DHMV_MAX_RESPONSE_MB`.
@@ -1295,6 +1301,12 @@ The full Kempen scope with all products means 28 municipalities times 12
 scenario rasters. This is intentionally explicit operator work, not startup
 work and not a browser-side provider fetch.
 
+The complete live matrix contains 336 ready Datasets and 336 DatasetVersions.
+The regional Map workspace deduplicates them into twelve scenario choices,
+renders all municipality image partitions for the selected scenario and uses
+`POST .../datasets/raster/flood-hazard/select` for exact bounded cross-boundary
+analysis. The same 12-million-cell guard prevents unsafe full-region reads.
+
 Use `--products pluviaal_current_t100`, `--resolution-m 5` or `--force` for an
 explicit subset/refresh. `POST .../raster/flood-hazard/select` returns mapped
 inundated hectares, selection share and local modeled maximum-depth statistics.