Download a verified file from another device over WebRTC

frontend/app.js

@@ -1786,10 +1786,11 @@ const Player = {
       btn.className = 'retry-btn';
       btn.textContent = '↻ Retry';
       btn.addEventListener('click', () => {
-        btn.remove();
+        els.playerPane.querySelectorAll('.retry-btn').forEach((b) => b.remove());
         Player.loadVideo(videoObj, { preferStream, resume, reveal, nocache });
       });
       els.playerPane.appendChild(btn);
+      offerPeerDownload(videoObj);
     }
   },
 
@@ -2465,6 +2466,65 @@ async function renderAvailability(id) {
   el.classList.remove('hidden');
 }
 
+// Fetch a verified copy from another device (docs/p2p-architecture.md flow 6).
+// Download-then-play: on success the file is saved offline like any save.
+async function getFromPeers(videoObj, c, peers, onProgress) {
+  const id = videoObj.id;
+  downloading.add(id);
+  markCardCacheState(id, 'downloading');
+  updateDownloadBadge();
+  try {
+    const res = await window.P2PTransfer.download({ videoId: id, cid: c.cid, size: c.size, peers, onProgress });
+    if (res.ok) {
+      cachedIds.add(id);
+      cacheMutations++;
+      recordDeviceFile(id, { sha256: res.sha256, expectedSha: c.cid, size: res.size });
+      toast(`Saved "${videoObj.title || id}" from another device ✓`);
+    }
+    return res;
+  } finally {
+    downloading.delete(id);
+    markCardCacheState(id, cachedIds.has(id) ? 'cached' : 'none');
+    updateDownloadBadge();
+    renderSidebar();
+  }
+}
+
+// Offered when a video won't load: only if some device holding it is online now.
+async function offerPeerDownload(videoObj) {
+  if (!WEB || !window.P2PTransfer || !window.P2PCore || data.settings.p2pReceive === false) return;
+  const id = videoObj && videoObj.id;
+  if (!id || videoObj.custom || cachedIds.has(id)) return;
+  let payload = null;
+  try {
+    const r = await fetch(`/api/p2p/holders?v=${encodeURIComponent(id)}`);
+    payload = r.ok ? await r.json() : null;
+  } catch { return; }
+  const c = payload && Array.isArray(payload.cids) ? payload.cids[0] : null;
+  const peers = c ? window.P2PCore.pickPeers(payload, c.cid) : [];
+  if (!peers.length || !els.playerPane.querySelector('.retry-btn')) return; // nobody online / user moved on
+  const old = els.playerPane.querySelector('.peer-btn');
+  if (old) old.remove();
+  const btn = document.createElement('button');
+  btn.className = 'retry-btn peer-btn';
+  btn.textContent = `📡 Get it from a device (${peers.length} online)`;
+  btn.addEventListener('click', async () => {
+    btn.disabled = true;
+    const res = await getFromPeers(videoObj, c, peers, (got, total) => {
+      btn.textContent = `📡 ${Math.min(99, Math.round((got / total) * 100))}%…`;
+    });
+    if (res.ok) {
+      els.playerPane.querySelectorAll('.retry-btn').forEach((b) => b.remove());
+      Player.loadVideo(videoObj);
+    } else {
+      btn.disabled = false;
+      btn.textContent = '📡 Try again';
+      toast('⚠ ' + res.error);
+    }
+  });
+  els.playerPane.appendChild(btn);
+}
+
 // Reflect cache state on the now-playing Save button.
 function updateNowPlayingActions() {
   if (!current || !current.meta) return;
@@ -9981,6 +10041,7 @@ async function boot() {
   // Peer-to-peer: report what this device holds (on by default; settings.p2pShare).
   if (WEB && window.P2PClient) {
     window.P2PClient.start({ getSettings: () => data.settings, getProfile: () => (data.profile && data.profile.name) || '' });
+    if (window.P2PTransfer) window.P2PTransfer.start({ canShare: () => data.settings.p2pShare !== false });
   }
   data.playlists.forEach(preloadPlaylist);
   preloadPinnedPlaylists();