good

frontend/src/lib/overlays.ts

@@ -1,4 +1,9 @@
-export const OVERLAY_IDS = ['noise', 'crime-hotspots', 'trees-outside-woodlands'] as const;
+export const OVERLAY_IDS = [
+  'noise',
+  'crime-hotspots',
+  'trees-outside-woodlands',
+  'property-borders',
+] as const;
 
 export type OverlayId = (typeof OVERLAY_IDS)[number];
 
@@ -26,10 +31,17 @@ export const OVERLAYS: OverlayDefinition[] = [
   },
   {
     id: 'trees-outside-woodlands',
-    label: 'Trees',
-    description: 'Trees Outside Woodland canopy polygons',
+    label: 'Trees & woodland',
+    description: 'Tree canopy and woodland polygons',
     detail:
-      'Forest Research Trees Outside Woodland (TOW) v1 canopy polygons covering lone trees and groups of trees outside mapped woodland blocks. Useful for spotting tree-lined streets and green pockets that broader land-use layers miss. Polygon opacity scales with canopy area.',
+      'Forest Research Trees Outside Woodland (TOW) v1 canopy polygons — lone trees and groups of trees — unioned with National Forest Inventory (NFI) woodland blocks (≥0.5 ha) that TOW deliberately excludes. Together they cover both street trees and actual woods. Polygon opacity scales with canopy area.',
+  },
+  {
+    id: 'property-borders',
+    label: 'Property borders',
+    description: 'Individual freehold property/land-parcel boundaries',
+    detail:
+      'HM Land Registry INSPIRE Index Polygons — the position and indicative extent of freehold registered property in England & Wales, drawn as outlines at street level. These are "general boundaries" for guidance only, not the precise legal boundary of a property, and they exclude leasehold-only interests and unregistered land (roughly 85–90% of freehold land is covered). This information is subject to Crown copyright and database rights 2026 and is reproduced with the permission of HM Land Registry. The polygons (including the associated geometry, namely x, y co-ordinates) are subject to Crown copyright and database rights 2026 Ordnance Survey AC0000851063. Licensed under the Open Government Licence v3.0.',
   },
 ];
 
@@ -38,3 +50,18 @@ const OVERLAY_ID_SET = new Set<string>(OVERLAY_IDS);
 export function isOverlayId(value: string): value is OverlayId {
   return OVERLAY_ID_SET.has(value);
 }
+
+/**
+ * Lowest zoom at which each overlay's tiles are generated by the pipeline
+ * (see the `--min-zoom` defaults in pipeline/transform/*_tiles.py). Used as
+ * the tile source's `minzoom` so we don't request tiles that don't exist —
+ * this is a data-availability floor, NOT the visibility limit. The limit at
+ * which overlays (and postcodes) start showing is the shared
+ * POSTCODE_ZOOM_THRESHOLD.
+ */
+export const OVERLAY_MIN_ZOOM: Record<OverlayId, number> = {
+  'crime-hotspots': 12,
+  noise: 12,
+  'property-borders': 12,
+  'trees-outside-woodlands': 12,
+};