Persist map selections as derived datasets

docs/API_CONTRACTS.md

@@ -406,6 +406,40 @@ Rules:
 - Results are generated from persisted PostGIS `vector_features`, not from client-side map data.
 - The response is capped by `limit` and returns `truncated=true` when more matching rows exist.
 
+### 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
+selected output into `vector_features`.
+
+Request:
+
+```json
+{
+  "bbox": {
+    "min_x": 5.0,
+    "min_y": 51.0,
+    "max_x": 5.1,
+    "max_y": 51.1,
+    "crs": "EPSG:4326"
+  },
+  "limit": 250,
+  "output_name": "selected-buildings"
+}
+```
+
+Response: `DatasetRead` in the canonical API envelope.
+
+Rules:
+
+- Only vector/GeoJSON datasets are supported.
+- Coordinates are EPSG:4326 longitude/latitude.
+- The new dataset uses `dataset_role="derived"`, `source="operation:selection"`,
+  `source_name="map_selection"` and `derived_from_dataset_id` pointing to the
+  source dataset.
+- The persisted GeoJSON properties retain source provenance as
+  `source_dataset_id` and `source_vector_feature_id`.
+- Empty selections return `VECTOR_OPERATION_EMPTY_RESULT` and do not create a dataset.
+
 ### GET `/api/v1/projects/{project_id}/datasets/{dataset_id}/content`
 
 Returns stored vector dataset content through the canonical API envelope.

docs/CODEX_EXECUTION_LOG.md

@@ -1,3 +1,34 @@
+## Sprint 108 Map selection derived datasets (2026-06-25)
+
+Changed:
+- Added `POST /api/v1/projects/{project_id}/datasets/{dataset_id}/vector/select/derive`.
+- Added `VectorSelectionDeriveRequest` for bbox selection-to-derived-dataset requests.
+- Added `VectorOperationsService.derive_selection_dataset`, which selects persisted PostGIS `vector_features`, writes a derived GeoJSON dataset artifact, stores source provenance and re-indexes the derived features into `vector_features`.
+- Added `Save as dataset` to the Map workspace selection result state with loading/error/latest-dataset feedback.
+- Updated frontend dataset API typing and wiring for selection-derived datasets.
+- Updated `docs/API_CONTRACTS.md`, `backend/README.md`, `frontend/README.md`, `CHANGELOG.md` and `docs/TODO.md`.
+- Added regression coverage in `backend/tests/test_sprint108_map_selection_derived_dataset.py`.
+
+Validation:
+- RED: `python -m pytest backend\tests\test_sprint108_map_selection_derived_dataset.py -q` failed before implementation because the service, route and frontend contracts were absent.
+- `python -m pytest backend\tests\test_sprint108_map_selection_derived_dataset.py -q` passed: 4 tests.
+- `python -m compileall backend/app` passed.
+- `cd backend && python -m pytest -q` passed: 345 tests.
+- `cd frontend && npm run typecheck` passed.
+- `cd frontend && npm run build` passed.
+- `cd backend && python -m alembic heads` passed: `202606120900 (head)`.
+- `cd backend && python -m alembic upgrade head --sql` passed.
+- `bash -n scripts/live_migration_smoke.sh` passed.
+- `bash scripts/run_readiness_check.sh` passed.
+
+Limitations:
+- Selection-derived datasets are bbox-only and use EPSG:4326 coordinates.
+- Empty selections are rejected with `VECTOR_OPERATION_EMPTY_RESULT`.
+- No migrations, live provider fetching, AI dependency, real model behavior or new product domain were added.
+
+Next recommended pass:
+- Run full release validation, deploy to `http://192.168.10.150:1202` and live-smoke `Save as dataset` from the Map workspace.
+
 ## Sprint 107 Map selection export handoff (2026-06-25)
 
 Changed:

docs/TODO.md

@@ -374,3 +374,4 @@ This file now starts with the current implementation status. Older preparation/b
 - [x] Add AI Lab action guardrails so explicit fixture models are not exposed as normal operator runs.
 - [x] Add persisted vector area selection from the Map workspace with bbox extract and GeoJSON download.
 - [x] Persist map area selections as Export Center handoff artifacts.
+- [x] Persist map area selections as reusable derived vector datasets indexed into `vector_features`.