/**
* Hermes WebUI Service Worker
* Minimal PWA service worker — enables "Add to Home Screen".
* No offline caching of API responses (the UI requires a live backend).
* Caches only static shell assets so the app shell loads fast on repeat visits.
*/
// Cache version is injected by the server at request time (routes.py /sw.js handler).
// Bumps automatically whenever the git commit changes — no manual edits needed.
const CACHE_NAME = 'hermes-shell-__CACHE_VERSION__';
// Static assets that form the app shell
const SHELL_ASSETS = [
'./',
'./static/style.css',
'./static/boot.js',
'./static/ui.js',
'./static/messages.js',
'./static/sessions.js',
'./static/panels.js',
'./static/commands.js',
'./static/icons.js',
'./static/i18n.js',
'./static/workspace.js',
'./static/onboarding.js',
'./static/favicon.svg',
'./static/favicon-32.png',
'./manifest.json',
];
// Install: pre-cache the app shell
self.addEventListener('install', (event) => {
event.waitUntil(
caches.open(CACHE_NAME).then((cache) => {
return cache.addAll(SHELL_ASSETS).catch((err) => {
// Non-fatal: if any asset fails, still activate
console.warn('[sw] Shell pre-cache partial failure:', err);
});
})
);
self.skipWaiting();
});
// Activate: clean up old caches
self.addEventListener('activate', (event) => {
event.waitUntil(
caches.keys().then((keys) =>
Promise.all(
keys.filter((k) => k !== CACHE_NAME).map((k) => caches.delete(k))
)
)
);
self.clients.claim();
});
// Fetch strategy:
// - API calls (/api/*, /stream) → always network (never cache)
// - Shell assets → cache-first with network fallback
// - Everything else → network-first, fall back to offline page
self.addEventListener('fetch', (event) => {
const url = new URL(event.request.url);
// Never intercept cross-origin requests
if (url.origin !== self.location.origin) return;
// API and streaming endpoints — always go to network
if (
url.pathname.startsWith('/api/') ||
url.pathname.includes('/stream') ||
url.pathname.startsWith('/health')
) {
return; // let browser handle normally
}
// Shell assets: cache-first
event.respondWith(
caches.match(event.request).then((cached) => {
if (cached) return cached;
return fetch(event.request).then((response) => {
// Cache successful GET responses for shell assets
if (
event.request.method === 'GET' &&
response.status === 200
) {
const clone = response.clone();
caches.open(CACHE_NAME).then((cache) => cache.put(event.request, clone));
}
return response;
}).catch(() => {
// Offline fallback for navigation requests.
// Note: caches.match() returns a Promise (always truthy in a `||` check),
// so we must await/then to unwrap it — otherwise the `new Response(...)`
// branch is dead code and the browser falls back to its default offline page.
if (event.request.mode === 'navigate') {
return caches.match('./').then((cached) => cached || new Response(
'' +
'You are offline
' +
'Hermes requires a server connection. Please check your network and try again.
' +
'',
{ headers: { 'Content-Type': 'text/html' } }
));
}
});
})
);
});