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/offline.js

@@ -0,0 +1,16 @@
+'use strict';
+// Save podcast episodes on this device, so they play with no signal. They live in the browser's own storage (a cache the service worker answers from),
+// so they are not synced between devices, and the browser may clear them if the phone runs low on space.
+const OFFLINE = 'hub-offline';
+const offUrl = id => '/api/podcast/podcasts/' + encodeURIComponent(id) + '/file';
+const offHas = async id => { try { return !!(await (await caches.open(OFFLINE)).match(offUrl(id))); } catch { return false; } };
+async function offSave(id, onDone) {
+  if (!('caches' in window)) { toast('This browser cannot save for offline'); return; }
+  toast('Saving…');
+  try {
+    const r = await fetch(offUrl(id), { credentials: 'same-origin' }); if (!r.ok) throw new Error('Could not download (' + r.status + ')');
+    await (await caches.open(OFFLINE)).put(offUrl(id), r); toast('Saved on this device'); if (navigator.storage && navigator.storage.persist) navigator.storage.persist().catch(() => {});
+  } catch (e) { try { await (await caches.open(OFFLINE)).delete(offUrl(id)); } catch {} toast(e.message || 'Could not save'); }
+  if (onDone) onDone();
+}
+async function offRemove(id, onDone) { try { await (await caches.open(OFFLINE)).delete(offUrl(id)); toast('Removed from this device'); } catch {} if (onDone) onDone(); }