fix(maps): localize map POI pin titles to the user's language

server/src/nest/maps/maps.controller.ts

@@ -80,6 +80,7 @@ export class MapsController {
     @Query('west') west?: string,
     @Query('north') north?: string,
     @Query('east') east?: string,
+    @Query('lang') lang?: string,
   ) {
     if (!category) throw new HttpException({ error: 'A category is required' }, 400);
     const bbox = { south: Number(south), west: Number(west), north: Number(north), east: Number(east) };
@@ -87,7 +88,7 @@ export class MapsController {
       throw new HttpException({ error: 'A valid bbox (south, west, north, east) is required' }, 400);
     }
     try {
-      return await this.maps.pois(category, bbox);
+      return await this.maps.pois(category, bbox, lang);
     } catch (err: unknown) {
       throw toHttpException(err, 'POI search error', 500);
     }

server/src/nest/maps/maps.service.ts

@@ -89,7 +89,7 @@ export class MapsService {
   }
 
   // OSM-only POI search by category within a viewport bbox (never calls Google).
-  pois(category: string, bbox: { south: number; west: number; north: number; east: number }) {
-    return searchOverpassPois(category, bbox);
+  pois(category: string, bbox: { south: number; west: number; north: number; east: number }, lang?: string) {
+    return searchOverpassPois(category, bbox, lang);
   }
 }

server/src/services/mapsService.ts

@@ -437,6 +437,7 @@ async function overpassFetch(query: string): Promise<OverpassPoiElement[]> {
 export async function searchOverpassPois(
   category: string,
   bbox: { south: number; west: number; north: number; east: number },
+  lang?: string,
   limit = 60,
 ): Promise<PoiSearchResult> {
   const filters = CATEGORY_OSM_FILTERS[category];
@@ -459,8 +460,15 @@ export async function searchOverpassPois(
     clamped = true;
   }
 
+  // OSM `name:*` tags are keyed by language subtag: prefer the user's language
+  // (the same localization the search/autocomplete path asks the geocoder for)
+  // over the native `name`. `int_name` is OSM's international/romanized name — a
+  // sensible fallback before the native one. Part of the cache key so a cached
+  // area isn't served with another language's titles.
+  const osmLang = toApiLang(lang).split('-')[0].toLowerCase();
+
   // Serve repeat pans/toggles of the same area straight from the cache.
-  const cacheKey = `${category}|${south.toFixed(2)},${west.toFixed(2)},${north.toFixed(2)},${east.toFixed(2)}|${limit}`;
+  const cacheKey = `${category}|${osmLang}|${south.toFixed(2)},${west.toFixed(2)},${north.toFixed(2)},${east.toFixed(2)}|${limit}`;
   const cached = POI_CACHE.get(cacheKey);
   if (cached && Date.now() - cached.at < POI_CACHE_TTL_MS) return cached.value;
   if (cached) POI_CACHE.delete(cacheKey); // expired — drop it before refetching
@@ -482,7 +490,7 @@ export async function searchOverpassPois(
   const pois: OverpassPoi[] = [];
   for (const el of elements) {
     const tags = el.tags || {};
-    const name = tags.name || tags['name:en'] || tags.brand || null;
+    const name = tags[`name:${osmLang}`] || tags['int_name'] || tags.name || tags.brand || null;
     if (!name) continue; // unnamed POIs aren't useful to add to a plan
     const lat = el.lat ?? el.center?.lat;
     const lng = el.lon ?? el.center?.lon;

server/tests/unit/nest/maps.controller.test.ts

@@ -98,11 +98,11 @@ describe('MapsController (parity with the legacy /api/maps route)', () => {
       expect(pois).not.toHaveBeenCalled();
     });
 
-    it('delegates a valid request with a parsed numeric bbox', async () => {
+    it('delegates a valid request with a parsed numeric bbox and forwards lang', async () => {
       const pois = vi.fn().mockResolvedValue({ places: [] });
-      const res = await makeController({ pois }).pois('cafe', '1', '2', '3', '4');
+      const res = await makeController({ pois }).pois('cafe', '1', '2', '3', '4', 'fr');
       expect(res).toEqual({ places: [] });
-      expect(pois).toHaveBeenCalledWith('cafe', { south: 1, west: 2, north: 3, east: 4 });
+      expect(pois).toHaveBeenCalledWith('cafe', { south: 1, west: 2, north: 3, east: 4 }, 'fr');
     });
 
     it('maps a service error, defaulting to 500', async () => {

server/tests/unit/nest/maps.service.test.ts

@@ -109,10 +109,10 @@ describe('MapsService', () => {
       expect(maps.resolveGoogleMapsUrl).toHaveBeenCalledWith('https://maps.app.goo.gl/x');
     });
 
-    it('pois forwards category and bbox through', () => {
+    it('pois forwards category, bbox and lang through', () => {
       const bbox = { south: 1, west: 2, north: 3, east: 4 };
-      svc().pois('cafe', bbox);
-      expect(maps.searchOverpassPois).toHaveBeenCalledWith('cafe', bbox);
+      svc().pois('cafe', bbox, 'de');
+      expect(maps.searchOverpassPois).toHaveBeenCalledWith('cafe', bbox, 'de');
     });
   });
 

server/tests/unit/services/mapsService.test.ts

@@ -583,6 +583,58 @@ describe('fetchOverpassDetails (fetch stubbed)', () => {
   });
 });
 
+// ── searchOverpassPois localized names (#1655) ───────────────────────────────
+
+describe('searchOverpassPois localized names (#1655)', () => {
+  // Elephant and Obelisk in Rome: OSM ships the native name plus localized tags.
+  const tags = {
+    name: 'Obelisco della Minerva',
+    'name:en': 'Elephant and Obelisk',
+    'name:de': 'Minerva-Obelisk',
+    int_name: 'Elephant Obelisk',
+    tourism: 'attraction',
+  };
+  const stubOverpass = (elementTags: Record<string, string>) =>
+    vi.stubGlobal(
+      'fetch',
+      vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({ elements: [{ type: 'node', id: 1, lat: 41.9, lon: 12.48, tags: elementTags }] }),
+      }),
+    );
+  // Distinct bboxes per case so the module-level POI_CACHE (keyed by lang+bbox)
+  // never serves one case's names to another.
+  const bbox = (n: number) => ({ south: 41 + n / 100, west: 12, north: 42 + n / 100, east: 13 });
+
+  it('prefers name:<lang> for the user language over the native name', async () => {
+    stubOverpass(tags);
+    const { searchOverpassPois } = await import('../../../src/services/mapsService');
+    const { pois } = await searchOverpassPois('sights', bbox(1), 'en-US');
+    expect(pois[0].name).toBe('Elephant and Obelisk');
+  });
+
+  it('localizes to a non-English language too', async () => {
+    stubOverpass(tags);
+    const { searchOverpassPois } = await import('../../../src/services/mapsService');
+    const { pois } = await searchOverpassPois('sights', bbox(2), 'de-DE');
+    expect(pois[0].name).toBe('Minerva-Obelisk');
+  });
+
+  it('falls back to int_name when the language tag is absent', async () => {
+    stubOverpass({ name: tags.name, int_name: tags.int_name, tourism: 'attraction' });
+    const { searchOverpassPois } = await import('../../../src/services/mapsService');
+    const { pois } = await searchOverpassPois('sights', bbox(3), 'fr-FR');
+    expect(pois[0].name).toBe('Elephant Obelisk');
+  });
+
+  it('falls back to the native name when no localized tag exists', async () => {
+    stubOverpass({ name: tags.name, tourism: 'attraction' });
+    const { searchOverpassPois } = await import('../../../src/services/mapsService');
+    const { pois } = await searchOverpassPois('sights', bbox(4), 'fr-FR');
+    expect(pois[0].name).toBe('Obelisco della Minerva');
+  });
+});
+
 // ── fetchWikimediaPhoto (fetch stubbed) ───────────────────────────────────────
 
 describe('fetchWikimediaPhoto (fetch stubbed)', () => {