kin: BATON-ARCH-009-frontend_dev

frontend/sw.js

@@ -0,0 +1,60 @@
+'use strict';
+
+const CACHE_NAME = 'baton-v1';
+
+// App shell assets to precache
+const APP_SHELL = [
+  '/',
+  '/index.html',
+  '/app.js',
+  '/style.css',
+  '/manifest.json',
+  '/icons/icon-192.png',
+  '/icons/icon-512.png',
+];
+
+// Install: precache app shell + skipWaiting so new SW activates immediately
+self.addEventListener('install', (event) => {
+  self.skipWaiting();
+  event.waitUntil(
+    caches.open(CACHE_NAME).then((cache) => cache.addAll(APP_SHELL))
+  );
+});
+
+// Activate: delete stale caches + claim open clients (decision: skipWaiting + clients.claim)
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches
+      .keys()
+      .then((keys) =>
+        Promise.all(
+          keys.filter((k) => k !== CACHE_NAME).map((k) => caches.delete(k))
+        )
+      )
+      .then(() => self.clients.claim())
+  );
+});
+
+// Fetch: cache-first for app shell; API calls pass through to network
+self.addEventListener('fetch', (event) => {
+  if (event.request.method !== 'GET') return;
+
+  const url = new URL(event.request.url);
+
+  // Never intercept API calls — they must always reach the server
+  if (url.pathname.startsWith('/api/')) return;
+
+  event.respondWith(
+    caches.match(event.request).then((cached) => {
+      if (cached) return cached;
+
+      return fetch(event.request).then((response) => {
+        if (response && response.status === 200) {
+          const clone = response.clone();
+          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, clone));
+        }
+        return response;
+      });
+    })
+  );
+});