sw.js

const CACHE = 'bp-trainer-v5';
const ASSETS = [
  './', './index.html', './manifest.json', './icon.svg', './og-image.png',
  './icons/icon-180.png', './icons/icon-192.png', './icons/icon-512.png',
  './icons/icon-maskable-192.png', './icons/icon-maskable-512.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();
});

self.addEventListener('fetch', e => {
  e.respondWith(
    caches.match(e.request).then(cached => cached || fetch(e.request))
  );
});