cache emojis with service worker

packages/nicolium/src/service-worker/sw.ts

@@ -326,6 +326,43 @@ const handleNotificationClick = (event: NotificationEvent) => {
   event.waitUntil(reactToNotificationClick);
 };
 
+// --- Asset caching ---
+
+const CACHE_NAME = 'ncd-assets-v1';
+
+/** URL patterns to cache with a cache-first strategy. */
+const CACHEABLE_PATTERNS = [
+  /\/packs\/emoji\/.*\.svg$/, // Built-in emoji SVGs
+  /\/packs\/assets\/.*\.woff2?$/, // Font files
+  /\/packs\/assets\/.*\.css$/, // Stylesheets
+  /\/emoji\/.*\.(png|svg|gif|webp)$/, // Custom instance emojis
+];
+
+const isCacheable = (url: string): boolean =>
+  CACHEABLE_PATTERNS.some((pattern) => pattern.test(url));
+
+/** Cache-first fetch handler for static assets. */
+const handleFetch = (event: FetchEvent) => {
+  const { request } = event;
+
+  if (request.method !== 'GET' || !isCacheable(request.url)) return;
+
+  event.respondWith(
+    caches.match(request).then((cached) => {
+      if (cached) return cached;
+
+      return fetch(request).then((response) => {
+        if (response.ok) {
+          const clone = response.clone();
+          caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));
+        }
+        return response;
+      });
+    }),
+  );
+};
+
 // ServiceWorker event listeners
 self.addEventListener('push', handlePush);
 self.addEventListener('notificationclick', handleNotificationClick);
+self.addEventListener('fetch', handleFetch);