sw.js

// Bump this on every deploy that changes any cached file — the version
// string is the only thing that makes an update actually replace the cache.
const CACHE_NAME = 'game-timer-v4';
const CACHE_FILES = [
  './',
  './index.html',
  './styles.css',
  './app.js',
  './manifest.webmanifest',
  './icons/icon-192.png',
  './icons/icon-512.png'
];

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then((cache) => cache.addAll(CACHE_FILES))
      .then(() => self.skipWaiting())
  );
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((names) =>
      Promise.all(names.filter((n) => n !== CACHE_NAME).map((n) => caches.delete(n)))
    ).then(() => self.clients.claim())
  );
});

// Cache-first: this is a static app, freshness matters far less than working
// offline on a tablet with no network in the middle of a game.
self.addEventListener('fetch', (event) => {
  if (event.request.method !== 'GET') return;
  event.respondWith(
    caches.match(event.request).then((cached) => {
      if (cached) return cached;
      return fetch(event.request).then((response) => {
        if (response && response.ok) {
          const copy = response.clone();
          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, copy));
        }
        return response;
      }).catch(() => cached);
    })
  );
});