sw.js

const CACHE = 'keto-v8';

const ASSETS = [
  './',
  './manifest.json',
  './icons/icon-192.png',
  './icons/icon-512.png',
  './icons/icon-512-maskable.png',
];

self.addEventListener('install', e => {
  e.waitUntil(
    caches.open(CACHE).then(c => c.addAll(ASSETS))
  );
  self.skipWaiting();
});

self.addEventListener('activate', e => {
  e.waitUntil(
    caches.keys().then(keys =>
      Promise.all(keys.filter(k => k !== CACHE).map(k => caches.delete(k)))
    )
  );
  self.clients.claim();
});

// Cache-first: serve cached asset, fall back to network.
// On network success, update the cache in the background.
self.addEventListener('fetch', e => {
  if (e.request.method !== 'GET') return;
  e.respondWith(
    caches.match(e.request).then(cached => {
      const networkFetch = fetch(e.request).then(res => {
        if (res && res.status === 200 && res.type !== 'opaque') {
          caches.open(CACHE).then(c => c.put(e.request, res.clone()));
        }
        return res;
      }).catch(() => null);
      return cached || networkFetch;
    })
  );
});