MosswartOverlord/static/sw.js

// Service worker for MosswartOverlord v2 — caches static assets for instant repeat loads
const CACHE_NAME = 'mo-v2-cache-v1';
const STATIC_ASSETS = [
  '/dereth.png',
  '/dereth_highres.png',
  '/prismatic-taper-icon.png',
  '/icons/0600127E.png',
  '/icons/06000133.png',
  '/icons/06001080.png',
];

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

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

self.addEventListener('fetch', (event) => {
  const url = new URL(event.request.url);

  // Cache icon images on first fetch
  if (url.pathname.startsWith('/icons/') && event.request.method === 'GET') {
    event.respondWith(
      caches.match(event.request).then(cached => {
        if (cached) return cached;
        return fetch(event.request).then(response => {
          if (response.ok) {
            const clone = response.clone();
            caches.open(CACHE_NAME).then(cache => cache.put(event.request, clone));
          }
          return response;
        });
      })
    );
    return;
  }

  // Cache dungeon_tiles.json (large, rarely changes)
  if (url.pathname === '/dungeon_tiles.json') {
    event.respondWith(
      caches.match(event.request).then(cached => {
        if (cached) return cached;
        return fetch(event.request).then(response => {
          if (response.ok) {
            const clone = response.clone();
            caches.open(CACHE_NAME).then(cache => cache.put(event.request, clone));
          }
          return response;
        });
      })
    );
    return;
  }

  // Cache static assets (map images etc)
  if (STATIC_ASSETS.some(a => url.pathname === a)) {
    event.respondWith(
      caches.match(event.request).then(cached => cached || fetch(event.request))
    );
    return;
  }
});