sw.js

const CACHE_NAME = 'celnav-v20';
const FONT_CACHE = 'celnav-fonts-v1';

const SHELL_ASSETS = [
  './',
  'index.html',
  'almanac.html',
  'manifest.json',
  'icon.svg',
  'icon-180.png',
  'icon-192.png',
  'icon-512.png',
  'coastline.js',
  'https://unpkg.com/leaflet@1.9.4/dist/leaflet.css',
  'https://unpkg.com/leaflet@1.9.4/dist/leaflet.js',
  'https://fonts.googleapis.com/css2?family=Cinzel:wght@400;600&family=Share+Tech+Mono&family=Crimson+Pro:ital,wght@0,300;0,400;1,300&display=swap',
  'https://fonts.googleapis.com/css2?family=STIX+Two+Text:ital,wght@0,400;0,700;1,400&family=Share+Tech+Mono&display=swap',
];

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

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

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

  // Skip non-GET requests
  if (e.request.method !== 'GET') return;

  // Skip chrome-extension and /api/ requests
  if (url.protocol === 'chrome-extension:') return;
  if (url.pathname.startsWith('/api/')) return;

  // Google Fonts (fonts.googleapis.com and fonts.gstatic.com) — cache-first, they're immutable
  if (url.hostname === 'fonts.googleapis.com' || url.hostname === 'fonts.gstatic.com') {
    e.respondWith(
      caches.open(FONT_CACHE).then(cache =>
        cache.match(e.request).then(cached => {
          if (cached) return cached;
          return fetch(e.request).then(response => {
            if (response && response.status === 200) {
              cache.put(e.request, response.clone());
            }
            return response;
          });
        })
      )
    );
    return;
  }

  // Same-origin requests — network-first, fall back to cache, then cached "/"
  if (url.origin === self.location.origin) {
    e.respondWith(
      fetch(e.request)
        .then(response => {
          if (response && response.status === 200) {
            const clone = response.clone();
            caches.open(CACHE_NAME).then(cache => cache.put(e.request, clone));
          }
          return response;
        })
        .catch(() =>
          caches.match(e.request).then(cached => cached || caches.match('./'))
        )
    );
    return;
  }

  // Other third-party (e.g. Leaflet CDN) — cache-first with network fallback
  e.respondWith(
    caches.match(e.request).then(cached => {
      if (cached) return cached;
      return fetch(e.request).then(response => {
        if (response && response.status === 200) {
          const clone = response.clone();
          caches.open(CACHE_NAME).then(cache => cache.put(e.request, clone));
        }
        return response;
      });
    })
  );
});