freezmo/public/sw.js

/**
 * Freezmo service worker (production only).
 *
 * Strategy, deliberately conservative:
 *   - API routes are never cached and never intercepted.
 *   - Navigations: network first, falling back to the cached shell, then /offline.
 *   - /_next/static + icons: stale-while-revalidate (fast, self-healing).
 *   - Everything else: straight to the network.
 *
 * Bumping CACHE_VERSION is how a new deploy invalidates old assets.
 */
const CACHE_VERSION = "freezmo-v5";
const SHELL_CACHE = `${CACHE_VERSION}-shell`;
const ASSET_CACHE = `${CACHE_VERSION}-assets`;

const SHELL_ASSETS = [
  "/",
  "/offline",
  "/manifest.webmanifest",
  "/icons/icon-192.png",
  "/icons/icon-512.png",
  "/icons/apple-touch-icon.png",
];

self.addEventListener("install", (event) => {
  event.waitUntil(
    (async () => {
      const cache = await caches.open(SHELL_CACHE);
      await Promise.allSettled(SHELL_ASSETS.map((url) => cache.add(new Request(url, { cache: "reload" }))));
      await self.skipWaiting();
    })(),
  );
});

self.addEventListener("activate", (event) => {
  event.waitUntil(
    (async () => {
      const names = await caches.keys();
      await Promise.all(
        names.filter((name) => !name.startsWith(CACHE_VERSION)).map((name) => caches.delete(name)),
      );
      await self.clients.claim();
    })(),
  );
});

function isCacheableAsset(url) {
  return (
    url.pathname.startsWith("/_next/static/") ||
    url.pathname.startsWith("/icons/") ||
    url.pathname === "/manifest.webmanifest" ||
    /\.(?:css|js|png|jpg|jpeg|svg|webp|woff2?)$/.test(url.pathname)
  );
}

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;
  // Never touch the API: keys, notes and generated decks must always be live.
  if (url.pathname.startsWith("/api/")) return;

  if (request.mode === "navigate") {
    event.respondWith(
      (async () => {
        try {
          const response = await fetch(request);
          const cache = await caches.open(SHELL_CACHE);
          cache.put("/", response.clone()).catch(() => {});
          return response;
        } catch {
          const cache = await caches.open(SHELL_CACHE);
          return (await cache.match("/")) ?? (await cache.match("/offline")) ?? Response.error();
        }
      })(),
    );
    return;
  }

  if (isCacheableAsset(url)) {
    event.respondWith(
      (async () => {
        const cache = await caches.open(ASSET_CACHE);
        const cached = await cache.match(request);
        const network = fetch(request)
          .then((response) => {
            if (response.ok) cache.put(request, response.clone()).catch(() => {});
            return response;
          })
          .catch(() => cached);
        return cached ?? network;
      })(),
    );
  }
});