--- a/frontend/p2p-client.js
+++ b/frontend/p2p-client.js
@@ -160,7 +160,7 @@
   // Send one saved video to the server so it can hash + validate it and add its
   // cid to the catalog. Uploads the whole file: only on the user's request
   // ("Verify & share") or when the server asks for a copy (plan 018).
-  async function contribute(videoId, { cid = null, title = '', channel = '' } = {}) {
+  async function contribute(videoId, { cid = null, title = '', channel = '', restore = false } = {}) {
     const dev = await ensureDevice();
     const rec = await window.DeviceDB.getFile(videoId);
     const file = window.OPFS.getFileObject ? await window.OPFS.getFileObject(videoId) : null;
@@ -168,7 +168,7 @@
     const h = { 'X-Device': dev.deviceId + '.' + dev.secret };
     const t = await (await fetch('/api/p2p/intake', {
       method: 'POST', headers: { ...h, 'Content-Type': 'application/json' },
-      body: JSON.stringify({ videoId, cid: cid || (rec && rec.cid) || undefined, size: file.size, title, channel }),
+      body: JSON.stringify({ videoId, cid: cid || (rec && rec.cid) || undefined, size: file.size, title, channel, restore }),
     })).json().catch(() => ({ ok: false, error: 'server unreachable' }));
     if (!t.ok || t.known) { if (t.known) changed(); return t; }
     const r = await (await fetch(t.url, { method: 'PUT', headers: h, body: file }))
@@ -280,6 +280,19 @@
     timer = setTimeout(sync, 5000);
   }
 
+  // Plan 018: the server lost its copy and the source is gone — it asks one
+  // holder to send the file back. Only while sharing is on, one at a time,
+  // and only for the exact cid this device holds.
+  let restoring = false;
+  onMessage('upload-request', async (m) => {
+    if (restoring || hooks.getSettings().p2pShare === false) return;
+    const rec = window.DeviceDB ? await window.DeviceDB.getFile(m.videoId) : null;
+    if (!rec || rec.cid !== m.cid) return;
+    restoring = true;
+    try { await contribute(m.videoId, { cid: m.cid, restore: true }); } catch { /* next request retries */ }
+    finally { restoring = false; }
+  });
+
   function start(h) {
     hooks = { ...hooks, ...(h || {}) };
     const idle = window.requestIdleCallback || ((fn) => setTimeout(fn, 1));