feat: add webchat pwa push subscription support

src/gateway/ui/sw.js

@@ -0,0 +1,92 @@
+const CACHE_NAME = 'flynn-webchat-v1';
+const token = new URL(self.location.href).searchParams.get('token');
+const withToken = (path) => {
+  if (!token) {
+    return path;
+  }
+  const sep = path.includes('?') ? '&' : '?';
+  return `${path}${sep}token=${encodeURIComponent(token)}`;
+};
+const OFFLINE_ASSETS = ['/', '/index.html', '/style.css', '/app.js', '/manifest.webmanifest'].map(withToken);
+
+self.addEventListener('install', (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME)
+      .then((cache) => cache.addAll(OFFLINE_ASSETS))
+      .catch(() => undefined),
+  );
+  self.skipWaiting();
+});
+
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((keys) => Promise.all(
+      keys
+        .filter((key) => key !== CACHE_NAME)
+        .map((key) => caches.delete(key)),
+    )),
+  );
+  self.clients.claim();
+});
+
+self.addEventListener('fetch', (event) => {
+  if (event.request.method !== 'GET') {
+    return;
+  }
+
+  event.respondWith((async () => {
+    const cached = await caches.match(event.request, { ignoreSearch: true });
+    if (cached) {
+      return cached;
+    }
+
+    try {
+      return await fetch(event.request);
+    } catch {
+      const fallback = await caches.match('/index.html', { ignoreSearch: true });
+      return fallback || new Response('Offline', { status: 503 });
+    }
+  })());
+});
+
+self.addEventListener('push', (event) => {
+  let payload = {
+    title: 'Flynn',
+    body: 'You have a new update.',
+  };
+
+  try {
+    const parsed = event.data?.json();
+    if (parsed && typeof parsed === 'object') {
+      payload = {
+        ...payload,
+        ...parsed,
+      };
+    }
+  } catch {
+    const text = event.data?.text();
+    if (text) {
+      payload.body = text;
+    }
+  }
+
+  event.waitUntil(self.registration.showNotification(payload.title, {
+    body: payload.body,
+    tag: payload.tag || 'flynn-webchat',
+    renotify: false,
+    data: payload.data || {},
+  }));
+});
+
+self.addEventListener('notificationclick', (event) => {
+  event.notification.close();
+
+  event.waitUntil((async () => {
+    const clients = await self.clients.matchAll({ type: 'window', includeUncontrolled: true });
+    if (clients.length > 0) {
+      await clients[0].focus();
+      return;
+    }
+    await self.clients.openWindow('/#/chat');
+  })());
+});