sw.js

/* OnTrack service worker.
   Scope: makes the app installable and lets the app shell (not user data,
   which lives in localStorage/Supabase, not the cache) load offline after
   the first visit. This does NOT implement push notifications — that
   needs a push subscription + a server to send from, which isn't wired
   up here. See SETUP.md for what real push delivery would require. */

const CACHE_NAME = 'ontrack-shell-v1';
const SHELL_FILES = [
  './',
  './index.html',
  './styles.css',
  './app.js',
  './supabase-config.js',
  './manifest.json',
  './icons/icon-192.png',
  './icons/icon-512.png'
];

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

self.addEventListener('fetch', (event) => {
  if (event.request.method !== 'GET') return;
  // Network-first for the Supabase API and CDN scripts so data is always
  // fresh when online; cache-first for the local app shell so it still
  // loads offline.
  const url = new URL(event.request.url);
  const isShellFile = url.origin === self.location.origin;
  if (!isShellFile) return; // let cross-origin requests (Supabase, CDN) go straight to network

  event.respondWith(
    caches.match(event.request).then((cached) => {
      const network = fetch(event.request).then((response) => {
        if (response && response.ok) {
          const clone = response.clone();
          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, clone));
        }
        return response;
      }).catch(() => cached);
      return cached || network;
    })
  );
});