sw.js

// Cache the small app shell for offline revisits. Same-origin assets are
// refreshed in the background when connected, preventing stale lessons.
const CACHE = 'agriempower-static-v2';
const ASSETS = [
  './', './index.html', './styles.css', './favicon.svg', './manifest.webmanifest',
  './assets/hero-farm.svg', './assets/icon-192.png', './assets/icon-512.png',
  './src/app.js', './src/data.js', './src/i18n.js', './src/icons.js',
  './src/storage.js', './src/utils.js'
];
self.addEventListener('install', event => {
  event.waitUntil(caches.open(CACHE).then(cache => cache.addAll(ASSETS)).then(() => self.skipWaiting()));
});
self.addEventListener('activate', event => {
  event.waitUntil(caches.keys().then(keys => Promise.all(keys.filter(key => key !== CACHE).map(key => caches.delete(key)))).then(() => self.clients.claim()));
});
self.addEventListener('fetch', event => {
  if (event.request.method !== 'GET') return;
  const requestURL = new URL(event.request.url);
  if (requestURL.origin !== self.location.origin) return;
  if (event.request.mode === 'navigate') {
    event.respondWith(fetch(event.request).then(response => {
      if (response.ok) {
        const copy = response.clone();
        caches.open(CACHE).then(cache => cache.put(event.request, copy));
      }
      return response;
    }).catch(() => caches.match('./index.html')));
    return;
  }
  event.respondWith(caches.match(event.request).then(cached => {
    const update = fetch(event.request).then(response => {
      if (response.ok && response.type === 'basic') {
        const copy = response.clone();
        caches.open(CACHE).then(cache => cache.put(event.request, copy));
      }
      return response;
    }).catch(() => cached);
    return cached || update;
  }));
});