Made Jarvis more mobile friendly

server/web/static/service-worker.js

@@ -0,0 +1,36 @@
+const CACHE = 'jarvis-v1';
+const SHELL = [
+  '/static/style.css',
+  '/static/app.js',
+  '/static/icon.png',
+  '/static/logo.png',
+];
+
+self.addEventListener('install', e => {
+  e.waitUntil(
+    caches.open(CACHE).then(c => c.addAll(SHELL)).then(() => self.skipWaiting())
+  );
+});
+
+self.addEventListener('activate', e => {
+  e.waitUntil(
+    caches.keys()
+      .then(keys => Promise.all(keys.filter(k => k !== CACHE).map(k => caches.delete(k))))
+      .then(() => self.clients.claim())
+  );
+});
+
+self.addEventListener('fetch', e => {
+  const url = new URL(e.request.url);
+  if (url.pathname.startsWith('/static/')) {
+    // Cache-first for static assets
+    e.respondWith(
+      caches.match(e.request).then(r => r || fetch(e.request))
+    );
+  } else {
+    // Network-first for everything else (pages, API)
+    e.respondWith(
+      fetch(e.request).catch(() => caches.match(e.request))
+    );
+  }
+});