sw.js

const CACHE = 'math-haredim-v1';

const PRECACHE = [
  '/',
  '/index.html',
  '/learn/',
  '/learn/index.html',
  '/favicon.svg',
  '/icon-192.png',
  '/icon-512.png',
  '/shared/nav.js',
  '/manifest.json',
];

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

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

// Network-first: try live, fall back to cache
self.addEventListener('fetch', event => {
  if (event.request.method !== 'GET') return;
  const url = new URL(event.request.url);
  // Only handle same-origin requests
  if (url.origin !== location.origin) return;

  event.respondWith(
    fetch(event.request)
      .then(response => {
        if (response.ok) {
          const clone = response.clone();
          caches.open(CACHE).then(cache => cache.put(event.request, clone));
        }
        return response;
      })
      .catch(() =>
        caches.match(event.request).then(r => r || caches.match('/index.html'))
      )
  );
});