diff --git a/apps/planner/app/lib/overpass.ts b/apps/planner/app/lib/overpass.ts
new file mode 100644
index 0000000..48b1507
--- /dev/null
+++ b/apps/planner/app/lib/overpass.ts
@@ -0,0 +1,130 @@
+import type { PoiCategory } from "./poi-categories.ts";
+
+const OVERPASS_ENDPOINT = "https://overpass-api.de/api/interpreter";
+
+export interface Poi {
+  id: number;
+  lat: number;
+  lon: number;
+  name?: string;
+  category: string;
+  tags: Record<string, string>;
+}
+
+export interface BBox {
+  south: number;
+  west: number;
+  north: number;
+  east: number;
+}
+
+/**
+ * Build an Overpass QL query combining all enabled categories into a union.
+ */
+export function buildQuery(bbox: BBox, categories: PoiCategory[]): string {
+  const bboxStr = `${bbox.south},${bbox.west},${bbox.north},${bbox.east}`;
+  const unions = categories.map((c) => c.query).join("");
+  return `[out:json][timeout:15][bbox:${bboxStr}];(${unions});out center 200;`;
+}
+
+/**
+ * Parse Overpass JSON response into typed Poi objects.
+ */
+export function parseResponse(
+  data: { elements: Array<{
+    type: string;
+    id: number;
+    lat?: number;
+    lon?: number;
+    center?: { lat: number; lon: number };
+    tags?: Record<string, string>;
+  }> },
+  categories: PoiCategory[],
+): Poi[] {
+  const pois: Poi[] = [];
+
+  for (const el of data.elements) {
+    const lat = el.lat ?? el.center?.lat;
+    const lon = el.lon ?? el.center?.lon;
+    if (lat === undefined || lon === undefined) continue;
+
+    const tags = el.tags ?? {};
+    const category = matchCategory(tags, categories);
+    if (!category) continue;
+
+    pois.push({
+      id: el.id,
+      lat,
+      lon,
+      name: tags.name,
+      category: category.id,
+      tags,
+    });
+  }
+
+  return deduplicateById(pois);
+}
+
+/**
+ * Match an element's tags to the first matching category.
+ */
+function matchCategory(tags: Record<string, string>, categories: PoiCategory[]): PoiCategory | null {
+  for (const cat of categories) {
+    // Parse query fragments like 'nwr["amenity"="drinking_water"];'
+    const fragments = cat.query.split(";").filter(Boolean);
+    for (const frag of fragments) {
+      const match = frag.match(/\["(\w+)"="([^"]+)"\]/);
+      if (match && tags[match[1]!] === match[2]) return cat;
+    }
+  }
+  return null;
+}
+
+/**
+ * Deduplicate POIs by OSM node ID (same node may match multiple queries).
+ */
+export function deduplicateById(pois: Poi[]): Poi[] {
+  const seen = new Set<number>();
+  return pois.filter((poi) => {
+    if (seen.has(poi.id)) return false;
+    seen.add(poi.id);
+    return true;
+  });
+}
+
+/**
+ * Query the Overpass API for POIs within a bounding box.
+ */
+export async function queryPois(
+  bbox: BBox,
+  categories: PoiCategory[],
+  signal?: AbortSignal,
+): Promise<Poi[]> {
+  if (categories.length === 0) return [];
+
+  const query = buildQuery(bbox, categories);
+  const response = await fetch(OVERPASS_ENDPOINT, {
+    method: "POST",
+    headers: { "Content-Type": "application/x-www-form-urlencoded" },
+    body: `data=${encodeURIComponent(query)}`,
+    signal,
+  });
+
+  if (response.status === 429) {
+    throw new OverpassRateLimitError();
+  }
+
+  if (!response.ok) {
+    throw new Error(`Overpass API error: ${response.status}`);
+  }
+
+  const data = await response.json();
+  return parseResponse(data, categories);
+}
+
+export class OverpassRateLimitError extends Error {
+  constructor() {
+    super("Overpass API rate limit exceeded");
+    this.name = "OverpassRateLimitError";
+  }
+}
diff --git a/apps/planner/app/lib/poi-cache.ts b/apps/planner/app/lib/poi-cache.ts
new file mode 100644
index 0000000..2ee7eb2
--- /dev/null
+++ b/apps/planner/app/lib/poi-cache.ts
@@ -0,0 +1,86 @@
+import type { Poi, BBox } from "./overpass.ts";
+
+const CELL_SIZE = 0.1; // degrees
+const TTL = 10 * 60 * 1000; // 10 minutes
+
+interface CacheEntry {
+  pois: Poi[];
+  timestamp: number;
+}
+
+const cache = new Map<string, CacheEntry>();
+
+/**
+ * Quantize a coordinate to the nearest grid cell boundary.
+ */
+export function quantize(value: number): number {
+  return Math.floor(value / CELL_SIZE) * CELL_SIZE;
+}
+
+/**
+ * Generate cache keys for grid cells covering a bounding box.
+ */
+export function getCellKeys(bbox: BBox): string[] {
+  const keys: string[] = [];
+  const minLat = quantize(bbox.south);
+  const maxLat = quantize(bbox.north) + CELL_SIZE;
+  const minLon = quantize(bbox.west);
+  const maxLon = quantize(bbox.east) + CELL_SIZE;
+
+  for (let lat = minLat; lat < maxLat; lat += CELL_SIZE) {
+    for (let lon = minLon; lon < maxLon; lon += CELL_SIZE) {
+      keys.push(`${lat.toFixed(1)},${lon.toFixed(1)}`);
+    }
+  }
+  return keys;
+}
+
+/**
+ * Get cached POIs for a bounding box. Returns null if any cell is missing/expired.
+ */
+export function getCached(bbox: BBox, categoriesKey: string): Poi[] | null {
+  const keys = getCellKeys(bbox);
+  const now = Date.now();
+  const allPois: Poi[] = [];
+
+  for (const cellKey of keys) {
+    const fullKey = `${categoriesKey}:${cellKey}`;
+    const entry = cache.get(fullKey);
+    if (!entry || now - entry.timestamp > TTL) return null;
+    allPois.push(...entry.pois);
+  }
+
+  // Filter to only POIs actually within the requested bbox
+  return allPois.filter(
+    (p) => p.lat >= bbox.south && p.lat <= bbox.north && p.lon >= bbox.west && p.lon <= bbox.east,
+  );
+}
+
+/**
+ * Store POIs in the cache, split by grid cell.
+ */
+export function setCached(bbox: BBox, categoriesKey: string, pois: Poi[]): void {
+  const now = Date.now();
+  const keys = getCellKeys(bbox);
+
+  // Assign each POI to its grid cell
+  const cellPois = new Map<string, Poi[]>();
+  for (const key of keys) cellPois.set(key, []);
+
+  for (const poi of pois) {
+    const cellKey = `${quantize(poi.lat).toFixed(1)},${quantize(poi.lon).toFixed(1)}`;
+    const bucket = cellPois.get(cellKey);
+    if (bucket) bucket.push(poi);
+  }
+
+  for (const [cellKey, cellData] of cellPois) {
+    cache.set(`${categoriesKey}:${cellKey}`, { pois: cellData, timestamp: now });
+  }
+}
+
+/**
+ * Clear all cached data.
+ */
+export function clearCache(): void {
+  cache.clear();
+}
diff --git a/apps/planner/app/lib/poi-categories.ts b/apps/planner/app/lib/poi-categories.ts
new file mode 100644
index 0000000..6f016ad
--- /dev/null
+++ b/apps/planner/app/lib/poi-categories.ts
@@ -0,0 +1,90 @@
+export interface PoiCategory {
+  id: string;
+  name: string;
+  icon: string;
+  color: string;
+  query: string;
+  profiles?: string[];
+}
+
+export const poiCategories: PoiCategory[] = [
+  {
+    id: "drinking_water",
+    name: "poi.drinkingWater",
+    icon: "💧",
+    color: "#2563eb",
+    query: 'nwr["amenity"="drinking_water"];nwr["amenity"="water_point"];',
+  },
+  {
+    id: "shelter",
+    name: "poi.shelter",
+    icon: "🛖",
+    color: "#8B6D3A",
+    query: 'nwr["amenity"="shelter"];nwr["tourism"="wilderness_hut"];',
+    profiles: ["trekking"],
+  },
+  {
+    id: "camping",
+    name: "poi.camping",
+    icon: "⛺",
+    color: "#059669",
+    query: 'nwr["tourism"="camp_site"];nwr["tourism"="caravan_site"];nwr["tourism"="picnic_site"];',
+  },
+  {
+    id: "food",
+    name: "poi.food",
+    icon: "🍽️",
+    color: "#dc2626",
+    query: 'nwr["amenity"="restaurant"];nwr["amenity"="cafe"];nwr["amenity"="fast_food"];nwr["amenity"="pub"];nwr["amenity"="biergarten"];',
+  },
+  {
+    id: "groceries",
+    name: "poi.groceries",
+    icon: "🛒",
+    color: "#f97316",
+    query: 'nwr["shop"="supermarket"];nwr["shop"="convenience"];nwr["shop"="bakery"];',
+  },
+  {
+    id: "bike_infra",
+    name: "poi.bikeInfra",
+    icon: "🔧",
+    color: "#8b5cf6",
+    query: 'nwr["amenity"="bicycle_parking"];nwr["amenity"="bicycle_repair_station"];nwr["amenity"="bicycle_rental"];',
+    profiles: ["fastbike", "safety"],
+  },
+  {
+    id: "accommodation",
+    name: "poi.accommodation",
+    icon: "🏨",
+    color: "#0891b2",
+    query: 'nwr["tourism"="hotel"];nwr["tourism"="hostel"];nwr["tourism"="guest_house"];',
+  },
+  {
+    id: "viewpoints",
+    name: "poi.viewpoints",
+    icon: "👁️",
+    color: "#9333ea",
+    query: 'nwr["tourism"="viewpoint"];',
+    profiles: ["trekking"],
+  },
+  {
+    id: "toilets",
+    name: "poi.toilets",
+    icon: "🚻",
+    color: "#6b7280",
+    query: 'nwr["amenity"="toilets"];',
+  },
+];
+
+export function getCategoriesForProfile(profile: string): string[] {
+  return poiCategories
+    .filter((c) => c.profiles?.includes(profile))
+    .map((c) => c.id);
+}
+
+/** Profile → tile overlay mapping */
+export const profileOverlayDefaults: Record<string, string[]> = {
+  fastbike: ["waymarked-cycling"],
+  safety: ["waymarked-cycling"],
+  trekking: ["waymarked-hiking"],
+};
diff --git a/apps/planner/app/lib/use-pois.ts b/apps/planner/app/lib/use-pois.ts
new file mode 100644
index 0000000..de421b6
--- /dev/null
+++ b/apps/planner/app/lib/use-pois.ts
@@ -0,0 +1,106 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+import { queryPois, OverpassRateLimitError, type Poi, type BBox } from "./overpass.ts";
+import { getCached, setCached } from "./poi-cache.ts";
+import { poiCategories, type PoiCategory } from "./poi-categories.ts";
+
+const MIN_ZOOM = 12;
+const DEBOUNCE_MS = 500;
+const BACKOFF_BASE_MS = 5000;
+const MAX_BACKOFF_MS = 60000;
+
+export type PoiStatus = "idle" | "loading" | "loaded" | "zoom_too_low" | "rate_limited" | "error";
+
+export interface PoiState {
+  pois: Poi[];
+  status: PoiStatus;
+  enabledCategories: string[];
+  setEnabledCategories: (ids: string[]) => void;
+  toggleCategory: (id: string) => void;
+  refresh: (bbox: BBox, zoom: number) => void;
+}
+
+export function usePois(): PoiState {
+  const [pois, setPois] = useState<Poi[]>([]);
+  const [status, setStatus] = useState<PoiStatus>("idle");
+  const [enabledCategories, setEnabledCategories] = useState<string[]>([]);
+  const abortRef = useRef<AbortController | null>(null);
+  const debounceRef = useRef<ReturnType<typeof setTimeout>>(undefined);
+  const backoffRef = useRef(0);
+
+  const toggleCategory = useCallback((id: string) => {
+    setEnabledCategories((prev) =>
+      prev.includes(id) ? prev.filter((c) => c !== id) : [...prev, id],
+    );
+  }, []);
+
+  const refresh = useCallback(
+    (bbox: BBox, zoom: number) => {
+      if (debounceRef.current) clearTimeout(debounceRef.current);
+
+      if (enabledCategories.length === 0) {
+        setPois([]);
+        setStatus("idle");
+        return;
+      }
+
+      if (zoom < MIN_ZOOM) {
+        setPois([]);
+        setStatus("zoom_too_low");
+        return;
+      }
+
+      const categories = poiCategories.filter((c) => enabledCategories.includes(c.id));
+      const categoriesKey = enabledCategories.sort().join(",");
+
+      // Check cache first
+      const cached = getCached(bbox, categoriesKey);
+      if (cached) {
+        setPois(cached);
+        setStatus("loaded");
+        return;
+      }
+
+      debounceRef.current = setTimeout(async () => {
+        // Cancel previous request
+        abortRef.current?.abort();
+        const controller = new AbortController();
+        abortRef.current = controller;
+
+        setStatus("loading");
+
+        try {
+          const result = await queryPois(bbox, categories, controller.signal);
+          if (controller.signal.aborted) return;
+
+          setCached(bbox, categoriesKey, result);
+          setPois(result);
+          setStatus("loaded");
+          backoffRef.current = 0;
+        } catch (err) {
+          if (controller.signal.aborted) return;
+
+          if (err instanceof OverpassRateLimitError) {
+            setStatus("rate_limited");
+            backoffRef.current = Math.min(
+              (backoffRef.current || BACKOFF_BASE_MS) * 2,
+              MAX_BACKOFF_MS,
+            );
+          } else {
+            setStatus("error");
+          }
+        }
+      }, DEBOUNCE_MS);
+    },
+    [enabledCategories],
+  );
+
+  // Cleanup on unmount
+  useEffect(() => {
+    return () => {
+      abortRef.current?.abort();
+      if (debounceRef.current) clearTimeout(debounceRef.current);
+    };
+  }, []);
+
+  return { pois, status, enabledCategories, setEnabledCategories, toggleCategory, refresh };
+}
diff --git a/openspec/changes/osm-overlays/tasks.md b/openspec/changes/osm-overlays/tasks.md
index 16bcb6e..722c4fc 100644
--- a/openspec/changes/osm-overlays/tasks.md
+++ b/openspec/changes/osm-overlays/tasks.md
@@ -13,23 +13,23 @@
 
 ## 3. Overpass Client
 
-- [ ] 3.1 Create `apps/planner/app/lib/overpass.ts` with `queryPois(bbox, categories)` function
-- [ ] 3.2 Build Overpass QL union queries from enabled POI category configs
-- [ ] 3.3 Parse `[out:json]` response into typed `Poi` objects (id, lat, lon, name, category, tags)
-- [ ] 3.4 Deduplicate results by OSM node ID (same node may match multiple tag queries)
+- [x] 3.1 Create `apps/planner/app/lib/overpass.ts` with `queryPois(bbox, categories)` function
+- [x] 3.2 Build Overpass QL union queries from enabled POI category configs
+- [x] 3.3 Parse `[out:json]` response into typed `Poi` objects (id, lat, lon, name, category, tags)
+- [x] 3.4 Deduplicate results by OSM node ID (same node may match multiple tag queries)
 
 ## 4. POI Caching & Rate Limiting
 
-- [ ] 4.1 Implement tile-based cache: quantize viewport to 0.1° grid cells, cache per cell with 10-minute TTL
-- [ ] 4.2 Add 500ms debounce on map `moveend` before triggering Overpass query
-- [ ] 4.3 Use AbortController to cancel in-flight requests when viewport changes
-- [ ] 4.4 Handle 429 responses with exponential backoff and user-visible message
-- [ ] 4.5 Enforce zoom >= 12 threshold — show "Zoom in to see POIs" message below
+- [x] 4.1 Implement tile-based cache: quantize viewport to 0.1° grid cells, cache per cell with 10-minute TTL
+- [x] 4.2 Add 500ms debounce on map `moveend` before triggering Overpass query
+- [x] 4.3 Use AbortController to cancel in-flight requests when viewport changes
+- [x] 4.4 Handle 429 responses with exponential backoff and user-visible message
+- [x] 4.5 Enforce zoom >= 12 threshold — show "Zoom in to see POIs" message below
 
 ## 5. POI Category Configuration
 
-- [ ] 5.1 Define `PoiCategory` type and initial category configs (water, shelter, camping, food, groceries, bike infra, accommodation, viewpoints, toilets)
-- [ ] 5.2 Map each category to Overpass QL tag queries, icon, color, and applicable routing profiles
+- [x] 5.1 Define `PoiCategory` type and initial category configs (water, shelter, camping, food, groceries, bike infra, accommodation, viewpoints, toilets)
+- [x] 5.2 Map each category to Overpass QL tag queries, icon, color, and applicable routing profiles
 
 ## 6. POI Overlay Panel