Expand BWK nature data across Kempen

frontend/README.md

@@ -529,3 +529,13 @@ integral as current, permanent or concurrent water volume.
 - `docs/40-build-launch/SPRINT_1_SCOPE_FREEZE.md`
 - `docs/API_CONTRACTS.md`
 - `docs/REPOSITORY_CONVENTIONS.md`
+
+## Area-aware map layer selection
+
+Map themes can have both a complete regional Dataset and a smaller exact-Area
+snapshot from the same official source. The workbench prefers the Dataset whose
+`area_id` exactly matches the selected Area; when no exact snapshot exists, the
+regional Dataset remains available and the backend clips metrics and map output
+to the selected municipality or drawn rectangle. The Sources workspace reports
+overlapping BWK area snapshots as separate coverages and does not sum their
+feature counts as if they were disjoint observations.

frontend/src/components/datasets/SourceCatalogPanel.tsx

@@ -117,6 +117,10 @@ export function SourceCatalogPanel({ datasets }: SourceCatalogPanelProps): JSX.E
       String(dataset.source_metadata?.['product_key'] ?? 'most_recent') !== 'most_recent',
   )
   const bwkDatasets = ready.filter((dataset) => dataset.source_name === 'inbo_bwk_natura2000')
+  const largestBwkSnapshot = bwkDatasets.reduce<DatasetCreateResponse | null>(
+    (largest, dataset) => !largest || (dataset.feature_count ?? 0) > (largest.feature_count ?? 0) ? dataset : largest,
+    null,
+  )
   const agricultureDatasets = ready.filter((dataset) => dataset.source_name === 'agentschap_landbouw_zeevisserij_agricultural_parcels')
   const buildingsRegisterDatasets = ready.filter(
     (dataset) => dataset.source_name === 'digitaal_vlaanderen_buildings_addresses_register',
@@ -214,7 +218,10 @@ export function SourceCatalogPanel({ datasets }: SourceCatalogPanelProps): JSX.E
           {bwkDatasets.length > 0 ? (
             <article>
               <strong>BWK / Natura 2000</strong>
-              <span>Toestand 2025 · {bwkDatasets.reduce((total, dataset) => total + (dataset.feature_count ?? 0), 0).toLocaleString('nl-BE')} kaartvlakken</span>
+              <span>
+                Toestand 2025 · {bwkDatasets.length} gebiedsdekking{bwkDatasets.length === 1 ? '' : 'en'} ·{' '}
+                {(largestBwkSnapshot?.feature_count ?? 0).toLocaleString('nl-BE')} kaartvlakken in de grootste dekking
+              </span>
               <p>Biologische waardering en habitataandelen blijven afzonderlijke, brongetrouwe metingen met herkomstinformatie.</p>
             </article>
           ) : null}

frontend/src/components/map/MapWorkspace.tsx

@@ -178,6 +178,7 @@ function pickThemeDataset(
   )
   candidates.sort((left, right) => {
     const score = (dataset: DatasetCreateResponse) =>
+      (dataset.area_id && dataset.area_id === selectedAreaId ? 10_000_000 : 0) +
       (dataset.reference_layer_name && theme.tokens.includes(dataset.reference_layer_name.toLowerCase()) ? 1_000_000 : 0) +
       (dataset.source_name === 'grb' ? 100_000 : 0) +
       (dataset.source_name === 'department_omgeving_land_use' ? 90_000 : 0) +