Polish dataset catalog role density

docs/CODEX_EXECUTION_LOG.md

@@ -2573,3 +2573,31 @@ Limitations:
 
 Next recommended pass:
 - Continue with Data catalog density polish, especially making selected/reference/candidate dataset roles easier to scan in populated demo projects.
+
+## Sprint 68 Data catalog density polish (2026-06-19)
+
+Changed:
+- Added a compact role summary to the Data catalog for Selected, Reference, Candidate and Source datasets.
+- Added scan-friendly dataset card badges plus source, reference layer and CRS context.
+- Treated non-reference vector/GeoJSON datasets as QA Candidate display roles in the frontend only, preserving persisted `dataset_role` values and API contracts.
+- Added responsive role-summary and role-badge CSS.
+- Added `backend/tests/test_sprint68_dataset_catalog_density.py`.
+- Updated `frontend/README.md`, `docs/TODO.md` and `CHANGELOG.md`.
+
+Tested:
+- Red step: `python -m pytest backend/tests/test_sprint68_dataset_catalog_density.py -q` failed on missing role summary, role badges and responsive CSS.
+- `python -m pytest backend/tests/test_sprint68_dataset_catalog_density.py backend/tests/test_sprint67_map_empty_state_quick_actions.py backend/tests/test_sprint30_workbench_components.py -q` (`10 passed`)
+- `cd frontend && npm run typecheck`
+- `cd frontend && npm run build`
+- Local browser check against `http://127.0.0.1:5175` with live API proxy: Data workspace showed Selected, Reference, Candidate and Source summary cards, with 1 Reference, 1 Candidate and 0 Source in the demo catalog; dataset badges rendered correctly on desktop and mobile, no console warnings/errors and no horizontal overflow.
+- Screenshots captured under `artifacts/sprint68-dataset-catalog-density/`.
+- `bash scripts/run_readiness_check.sh` (`243 passed`)
+
+Open:
+- Run full readiness, redeploy Tower and verify the live Data catalog after deployment.
+
+Limitations:
+- This is a frontend density/readability pass only. It does not change dataset persistence, backend role validation, API contracts, migrations, provider fetching or AI/model behavior.
+
+Next recommended pass:
+- Continue with Data workspace action polish, especially making QA/export affordances clearer once candidate and reference layers are present.

docs/TODO.md

@@ -339,3 +339,4 @@ This file now starts with the current implementation status. Older preparation/b
 - [x] Add export/report handoff polish for artifact readiness, action grouping and export provenance.
 - [x] Polish lightweight HTML project report readability, print styling and handoff sections.
 - [x] Add Map empty-state quick actions for ready vector datasets.
+- [x] Add Data catalog role-density polish for reference/candidate/source scanning.