fix(map): make area analysis scale-aware

docs/API_CONTRACTS.md

@@ -881,6 +881,24 @@ Rules:
 - `limit` is bounded to `1..1000`. Municipality-scale clients must page spatially by viewport instead of requesting an unbounded municipality FeatureCollection.
 - The Map workspace uses this existing endpoint for vector datasets above 5,000 features. It starts delivery at zoom level 14, debounces `moveend` requests and explicitly reports `truncated=true` as a request to zoom further in. This is a client delivery policy, not a second API or persistence path.
 
+### POST `/api/v1/projects/{project_id}/datasets/vector/partitions/select`
+
+Combines `1..16` bounded vector acquisitions of one governed source product
+into one read-only selection result. The request uses the same `bbox`, optional
+`area_id` and `limit` contract as vector selection plus `dataset_ids`.
+
+The backend rejects mixed projects, non-ready vector datasets and partitions
+whose `source_name` or `product_key` differs. PostGIS calculates area and length
+metrics across all persisted tile geometries. `total_feature_count` is
+deduplicated by provider `source_feature_id` where available so a source object
+crossing a tile edge is not presented as two objects. The response includes
+`partition_count`, `source_name` and the exact `dataset_ids` used.
+
+The Map workbench uses this route only for regional selections up to 50 by 50
+kilometres. Provider calls remain individually bounded below 20 kilometres;
+larger overview selections do not fan out into unbounded high-resolution
+downloads.
+
 ### POST `/api/v1/projects/{project_id}/datasets/{dataset_id}/vector/select/derive`
 
 Persists a bbox selection as a new derived vector dataset and indexes the

docs/CODEX_EXECUTION_LOG.md

@@ -10953,3 +10953,40 @@ Validation:
   themes through acquisition or persisted national data and semantic
   selection metrics;
 - browser verification follows against the deployed commit on port 1202.
+
+## 2026-07-21 - Scale-aware rectangle analysis
+
+Implemented:
+
+- reproduced the reported provider failure with an approximately 11,468 km2
+  cross-region rectangle: twenty high-resolution adapters received one unsafe
+  bbox and returned their governed size limits;
+- added explicit detail, regional and overview selection tiers before any
+  provider acquisition starts;
+- regional selections up to 50 by 50 km now split compatible vector and point
+  sources into at most sixteen 18 km tiles, resolve the authority zone per tile
+  and combine each provider product as one persisted PostGIS result;
+- added a canonical multi-partition vector selection route with project,
+  readiness and source-product consistency guards and source-feature count
+  deduplication;
+- allowed terrain and flood partition analysis to receive an explicit set of
+  freshly acquired Dataset ids, avoiding accidental reuse of overlapping old
+  bounded rasters;
+- kept 5 m raster analysis behind its real pixel budget and 10 m thematic
+  analysis behind its 50 km scale budget;
+- changed overview selections to query only national or already provisioned
+  scale-compatible datasets and explain the scale choice once, instead of
+  presenting one provider error for every unavailable detail source.
+
+Validation:
+
+- backend import/compile and frontend TypeScript passed after the contract
+  change;
+- focused selection-partition, DHMV and VMM tests passed (30 tests);
+- focused frontend scale, tiling and concurrency tests passed (12 tests).
+
+Remaining in this pass:
+
+- run the complete readiness gate, deploy the immutable revision and repeat
+  both the large overview rectangle and a regional partitioned rectangle in
+  the live browser.

docs/TODO.md

@@ -835,3 +835,14 @@ This file now starts with the current implementation status. Older preparation/b
   uncertainty tests exist; never merge TAW, LAT and mDNG implicitly.
 - [ ] Add water volume only when bed and water-surface inputs share a governed
   time, datum and coverage contract.
+
+# Scale-aware map selection
+
+- [x] Prevent country-scale rectangles from fan-out querying every local
+  provider and replace repeated source-limit errors with one overview status.
+- [x] Partition compatible 20-50 km regional vector acquisitions into bounded
+  source requests and combine their persisted PostGIS metrics.
+- [x] Keep terrain, flood and thematic rasters behind explicit pixel and
+  selection-size budgets.
+- [ ] Provision additional national-scale baseline datasets before exposing
+  more overview themes; do not synthesize regional detail at national scale.