sw.js

// Cache-once, serve-forever — no update checks needed
const CACHE = 'advantagedata-v8';

const PRECACHE = [
  './index.html',
  'https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.4.1/chart.umd.min.js',
  'https://cdnjs.cloudflare.com/ajax/libs/PapaParse/5.4.1/papaparse.min.js',
  'https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&display=swap',
];

self.addEventListener('install', e => {
  e.waitUntil(
    caches.open(CACHE).then(cache =>
      Promise.allSettled(PRECACHE.map(url => cache.add(url).catch(() => {})))
    ).then(() => self.skipWaiting())
  );
});

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

// Always serve from cache; only hit network if not cached yet
self.addEventListener('fetch', e => {
  e.respondWith(
    caches.match(e.request).then(cached => {
      if (cached) return cached;
      return fetch(e.request).then(res => {
        if (res.ok && res.type !== 'opaque')
          caches.open(CACHE).then(c => c.put(e.request, res.clone()));
        return res;
      });
    })
  );
});