sw.js

const CACHE_NAME = 'lb-core-v1';

self.addEventListener('install', event => {
    // Skip waiting to activate immediately
    self.skipWaiting();
});

self.addEventListener('activate', event => {
    // Claim clients immediately
    event.waitUntil(self.clients.claim());
});

self.addEventListener('fetch', event => {
    // Only intercept basic HTTP GET requests
    if (event.request.method !== 'GET') return;

    event.respondWith(
        fetch(event.request).then(response => {
            // Ensure response is valid before caching
            if (!response || response.status !== 200 || response.type !== 'basic') {
                return response;
            }

            // Clone the response stream and cache the latest version
            const responseToCache = response.clone();
            caches.open(CACHE_NAME).then(cache => {
                cache.put(event.request, responseToCache);
            });

            return response;
        }).catch(() => {
            // Network failed (offline), fallback to cache
            return caches.match(event.request).then(cachedResponse => {
                if (cachedResponse) {
                    return cachedResponse;
                }
            });
        })
    );
});