sw.js

const CACHE = 'bookshelf-v8';

const PRECACHE = [
  '/viewer.html',
  '/publications/the-next-frontier.md',
  '/publications/agent-event-loop.md',
  '/publications/the-verification-trap.md',
  '/logo-v2.png',
  '/books/',
  '/books/index.html',
  '/static/marked.min.js',
  '/static/highlight/highlight.min.js',
  '/static/highlight/github-dark.min.css',
  '/static/mermaid.min.js',
  '/static/fonts/fonts.css',
  '/static/fonts/Outfit-300.ttf',
  '/static/fonts/Outfit-400.ttf',
  '/static/fonts/Outfit-500.ttf',
  '/static/fonts/Outfit-600.ttf',
  '/static/fonts/Outfit-700.ttf',
  '/static/fonts/JetBrainsMono-400.ttf',
  '/static/fonts/JetBrainsMono-500.ttf',
  '/static/fonts/JetBrainsMono-600.ttf'
];

// Install: pre-cache all assets
self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE).then(cache =>
      cache.addAll(PRECACHE)
    ).then(() => self.skipWaiting())
  );
});

// Activate: clean old caches, take control immediately
self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(keys =>
      Promise.all(
        keys.filter(k => k !== CACHE).map(k => caches.delete(k))
      )
    ).then(() => self.clients.claim())
  );
});

// Fetch: cache-first for all self-hosted assets (no external deps)
self.addEventListener('fetch', event => {
  const url = new URL(event.request.url);

  // Only handle GET requests
  if (event.request.method !== 'GET') return;

  // Skip non-http(s) protocols
  if (!url.protocol.startsWith('http')) return;

  // For our own domain — cache-first with stale-while-revalidate
  if (url.origin === self.location.origin) {
    event.respondWith(cacheFirst(event.request));
    return;
  }

  // Everything else — network only
});

async function cacheFirst(request) {
  const cached = await caches.match(request);
  if (cached) {
    // Stale-while-revalidate: serve cached, update in background
    fetch(request).then(response => {
      if (response.ok) {
        caches.open(CACHE).then(cache => cache.put(request, response));
      }
    }).catch(() => {});
    return cached;
  }
  try {
    const response = await fetch(request);
    if (response.ok) {
      const clone = response.clone();
      caches.open(CACHE).then(cache => cache.put(request, clone));
    }
    return response;
  } catch (err) {
    return new Response('Offline', { status: 503 });
  }
}