Offline podcast episodes, Continue reading on Home, switch to turn off online lookups

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaC9HmtHMdRP8dAbN4wAKj

public/sw.js

@@ -1,5 +1,5 @@
 // App-shell cache only; Seafile/API traffic always goes to the network.
-const CACHE = 'hub-v48';
+const CACHE = 'hub-v49';
 const SHARE = 'hub-share'; // files shared into the app from other apps, held until the person picks a folder
 const SHELL = ['/icon.svg', '/manifest.webmanifest', '/icons/icon-192.png', '/icons/apple-touch-icon.png'];
 
@@ -22,6 +22,16 @@ self.addEventListener('activate', e => {
   e.waitUntil(caches.keys().then(ks => Promise.all(ks.filter(k => k !== CACHE).map(k => caches.delete(k)))));
   self.clients.claim();
 });
+// Podcast episodes saved on this device (see offline.js): answer from them, including the byte ranges an audio player asks for; otherwise use the network as normal.
+async function offlineAudio(req) {
+  const hit = await (await caches.open('hub-offline')).match(req.url);
+  if (!hit) return fetch(req);
+  const blob = await hit.blob(), size = blob.size, type = hit.headers.get('content-type') || 'audio/mpeg', m = /^bytes=(\d*)-(\d*)$/.exec(req.headers.get('range') || '');
+  if (!m) return new Response(blob, { status: 200, headers: { 'content-type': type, 'content-length': size, 'accept-ranges': 'bytes' } });
+  let a = m[1] === '' ? Math.max(0, size - +m[2]) : +m[1], b = m[1] === '' || m[2] === '' ? size - 1 : Math.min(+m[2], size - 1);
+  if (a > b || a >= size) return new Response(null, { status: 416, headers: { 'content-range': 'bytes */' + size } });
+  return new Response(blob.slice(a, b + 1), { status: 206, headers: { 'content-type': type, 'content-length': b - a + 1, 'content-range': `bytes ${a}-${b}/${size}`, 'accept-ranges': 'bytes' } });
+}
 // Share target: other apps send files here (POST); keep them and open the app, which asks where to put them.
 async function takeShare(request) {
   try {
@@ -35,6 +45,7 @@ async function takeShare(request) {
 self.addEventListener('fetch', e => {
   const u = new URL(e.request.url);
   if (e.request.method === 'POST' && u.origin === location.origin && u.pathname === '/share-target') return e.respondWith(takeShare(e.request));
+  if (e.request.method === 'GET' && u.origin === location.origin && /^\/api\/podcast\/podcasts\/[^/]+\/file$/.test(u.pathname)) return e.respondWith(offlineAudio(e.request));
   if (e.request.method !== 'GET' || u.origin !== location.origin || u.pathname.startsWith('/sf/') || u.pathname.startsWith('/plex/') || u.pathname.startsWith('/api/')) return;
   e.respondWith(fetch(e.request).then(r => {
     if (r.ok) { const copy = r.clone(); caches.open(CACHE).then(c => c.put(e.request, copy)); }