Match a place name across its inflected forms, and forget an empty answer quickly

server/src/nest/maps/maps.helpers.ts

@@ -95,13 +95,29 @@ export function namesOverlap(a: string, b: string): boolean {
         .split(/[^a-z0-9]+/)
         .filter((word) => word.length > 2),
     );
-  const left = words(a);
-  if (left.size === 0) return false;
+  const left = [...words(a)];
+  if (left.length === 0) return false;
+
+  /**
+   * Same word, allowing for an inflected ending.
+   *
+   * Providers localise names, and the two sides of this comparison rarely come
+   * from the same language: searching "Hamburg Airport" returns "Hamburger
+   * Flughafen Helmut Schmidt", and a plain equality test rejects its own
+   * correct answer over the "-er". A short prefix would over-match, so the
+   * shared stem has to carry weight and the endings have to be close.
+   */
+  const sameStem = (x: string, y: string): boolean => {
+    if (x === y) return true;
+    const [short, long] = x.length <= y.length ? [x, y] : [y, x];
+    return short.length >= 4 && long.length - short.length <= 3 && long.startsWith(short);
+  };
 
   let shared = 0;
   for (const word of words(b)) {
-    if (!left.has(word)) continue;
-    if (word.length >= 4) return true;
+    const match = left.find((candidate) => sameStem(candidate, word));
+    if (!match) continue;
+    if (Math.min(match.length, word.length) >= 4) return true;
     if (++shared >= 2) return true;
   }
   return false;

server/src/nest/place-enrichment/place-enrichment.service.ts

@@ -34,6 +34,21 @@ const GOOGLE_CAP = 3;
  */
 const CACHE_KIND = 2;
 const CACHE_TTL_MS = 7 * 24 * 60 * 60 * 1000;
+/**
+ * A week is right for an answer, and far too long for the absence of one.
+ *
+ * Nothing found is usually the provider having a bad minute — a Wikimedia
+ * timeout, a rate limit, a Nominatim hiccup — not a place that genuinely has no
+ * pictures and no article. Storing that under the same TTL means one unlucky
+ * request leaves the column blank for the rest of the week, which is exactly
+ * how a fix can look like no fix at all when it lands.
+ */
+const EMPTY_CACHE_TTL_MS = 10 * 60 * 1000;
+
+/** Whether an answer is worth keeping for a week. */
+function hasAnything(value: CachedEnrichment): boolean {
+  return !!(value.photos.length || value.description || value.facts.length || value.hours || value.rating);
+}
 /**
  * Bumped whenever the shape or the sources change. Without it a release that
  * adds a field or swaps a provider keeps serving the previous week's answers
@@ -593,7 +608,7 @@ export class PlaceEnrichmentService {
         lang ?? '',
         CACHE_KIND,
       );
-      if (!row || Date.now() - row.fetched_at >= CACHE_TTL_MS) return null;
+      if (!row) return null;
       const parsed = JSON.parse(row.payload_json) as CachePayload;
       if (parsed.v !== CACHE_VERSION) return null;
 
@@ -604,13 +619,18 @@ export class PlaceEnrichmentService {
       // of the week for a place that has pictures perfectly available.
       const photos = parsed.photos.filter((photo) => this.photoCache.get(photo.key));
       if (photos.length !== parsed.photos.length) return null;
-      return {
+
+      const value: CachedEnrichment = {
         photos,
         description: parsed.description ?? null,
         facts: parsed.facts ?? [],
         hours: parsed.hours ?? null,
         rating: parsed.rating ?? null,
       };
+      // An answer keeps for a week; the absence of one gets ten minutes.
+      const ttl = hasAnything(value) ? CACHE_TTL_MS : EMPTY_CACHE_TTL_MS;
+      if (Date.now() - row.fetched_at >= ttl) return null;
+      return value;
     } catch {
       return null;
     }

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

@@ -81,6 +81,18 @@ describe('namesOverlap', () => {
     expect(namesOverlap('Café Zürich', 'Cafe Zurich')).toBe(true);
   });
 
+  it('MAPS-162c: matches a name across an inflected ending', () => {
+    // Live case: searching "Hamburg Airport" returns OSM's "Hamburger
+    // Flughafen Helmut Schmidt". Insisting on exact words rejected the correct
+    // answer over an "-er", and the airport came back with nothing at all.
+    expect(namesOverlap('Hamburg Airport', 'Hamburger Flughafen Helmut Schmidt')).toBe(true);
+    expect(namesOverlap('Berlin Hauptbahnhof', 'Berliner Hauptbahnhof')).toBe(true);
+    // Still not a licence to match on a shared opening: the stem has to carry
+    // weight and the endings have to be close.
+    expect(namesOverlap('Bahn Museum', 'Bahnhofsvorplatz Kiosk')).toBe(false);
+    expect(namesOverlap('Alt Museum', 'Altenpflegeheim Nord')).toBe(false);
+  });
+
   it('MAPS-162b: will not match on a single short word', () => {
     // An article, and TREK speaks 23 languages — a stopword list for all of
     // them is its own problem, so weight decides instead.