sw.js

// Root-scope service worker for the agrun.js landing page.
// Sub-apps (/long-task-lab/, /example/) have their own runtimes — this SW
// ignores those paths so it never interferes with their request handling.

const CACHE_NAME = 'agrun-landing-shell-v1';

const SHELL_ASSETS = [
  '/',
  '/index.html',
  '/offline.html',
  '/manifest.webmanifest',
  '/icons/icon.svg',
  '/icons/maskable-icon.svg',
  '/icons/favicon.svg',
];

const IGNORED_PREFIXES = [
  '/long-task-lab/',
  '/example/',
  '/agrun_docs/',
  '/scripts/',
];

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

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

self.addEventListener('fetch', (event) => {
  const request = event.request;
  if (request.method !== 'GET') return;

  const url = new URL(request.url);
  if (url.origin !== self.location.origin) return;
  if (IGNORED_PREFIXES.some((prefix) => url.pathname.startsWith(prefix))) return;

  if (request.mode === 'navigate') {
    event.respondWith(networkFirstNavigation(request));
    return;
  }

  event.respondWith(staleWhileRevalidate(request));
});

self.addEventListener('message', (event) => {
  if (event.data === 'SKIP_WAITING') self.skipWaiting();
});

async function networkFirstNavigation(request) {
  try {
    const response = await fetch(request);
    if (response && response.ok) {
      const cache = await caches.open(CACHE_NAME);
      cache.put('/', response.clone());
    }
    return response;
  } catch {
    const cached = await caches.match(request)
      || await caches.match('/')
      || await caches.match('/index.html');
    return cached || caches.match('/offline.html');
  }
}

async function staleWhileRevalidate(request) {
  const cached = await caches.match(request);
  const networkFetch = fetch(request).then(async (response) => {
    if (response && response.ok && response.type === 'basic') {
      const cache = await caches.open(CACHE_NAME);
      cache.put(request, response.clone());
    }
    return response;
  }).catch(() => cached);
  return cached || networkFetch || new Response('', { status: 504, statusText: 'Offline' });
}