diff --git a/src/backend/backend.js b/src/backend/backend.js
index d839e29..94d658b 100644
--- a/src/backend/backend.js
+++ b/src/backend/backend.js
@@ -3654,11 +3654,27 @@ router
   })
   .get('/karvan/:id', async (ctx) => {
     if (!checkMod(ctx, 'karvanMod')) { ctx.redirect('/modules'); return; }
-    const room = karvanModel.getRoom(ctx.params.id);
+    let room = karvanModel.getRoom(ctx.params.id);
+    if (!room) room = karvanModel.adoptRoom({ id: ctx.params.id }); // unirse por enlace/invitación (espejo local)
     if (!room) { ctx.redirect('/karvan'); return; }
     let selfId = ''; try { selfId = getViewerId(); } catch (e) {}
-    const msgs = karvanModel.listMessages(ctx.params.id, 0) || [];
-    ctx.body = karvanRoomView(room, msgs, { selfId });
+    const msgs = karvanModel.listMessages(room.id, 0) || [];
+    ctx.body = karvanRoomView(room, msgs, { selfId, invite: ctx.query.invite || '' });
+  })
+  .post('/karvan/:id/invite', koaBody(), async (ctx) => {
+    if (!checkMod(ctx, 'karvanMod')) { ctx.status = 403; ctx.body = { error: 'off' }; return; }
+    const id = ctx.params.id;
+    const room = karvanModel.getRoom(id);
+    if (!room) { ctx.redirect('/karvan'); return; }
+    const to = String((ctx.request.body || {}).to || '').trim();
+    if (!/^@[A-Za-z0-9+/=]{20,}\.ed25519$/.test(to)) { ctx.redirect('/karvan/' + id + '?invite=bad'); return; }
+    try {
+      // reutiliza el patrón de invitación por mensaje privado de Oasis (como el módulo industry):
+      // le llega al INBOX del contacto con un enlace a la sala. Sin código SSB nuevo.
+      await pmModel.sendMessage([to], 'KARVAN_INVITE',
+        'You have been invited to an ephemeral Karvan room' + (room.title ? ' ("' + room.title + '")' : '') + ' -> /karvan/' + id);
+      ctx.redirect('/karvan/' + id + '?invite=ok');
+    } catch (e) { ctx.redirect('/karvan/' + id + '?invite=fail'); }
   })
   .post('/karvan/:id/msg', koaBody(), async (ctx) => {
     if (!checkMod(ctx, 'karvanMod')) { ctx.status = 403; ctx.body = { error: 'off' }; return; }
diff --git a/src/client/assets/themes/OasisMobile.css b/src/client/assets/themes/OasisMobile.css
index 21be6b7..e015b8c 100644
--- a/src/client/assets/themes/OasisMobile.css
+++ b/src/client/assets/themes/OasisMobile.css
@@ -1184,6 +1184,14 @@ body { padding-top: 84px; }
 .karvan-compose { display: flex; gap: 8px; margin-top: 10px; }
 .karvan-compose input[type="text"] { flex: 1 1 auto; min-width: 0; padding: 10px 12px;
   background: #161616; border: 1px solid #333; border-radius: 10px; color: #FFD700; }
+/* Fase 2: invitar a un contacto por feed id */
+.karvan-invite { display: flex; gap: 8px; margin-top: 8px; }
+.karvan-invite input[type="text"] { flex: 1 1 auto; min-width: 0; padding: 9px 12px;
+  background: #161616; border: 1px solid #333; border-radius: 10px; color: #FFD700; font-family: monospace; font-size: 12px; }
+.karvan-invite button { flex: 0 0 auto; padding: 9px 14px; border: 1px solid #FFD700; background: #161616; color: #FFD700; border-radius: 10px; cursor: pointer; }
+.karvan-invite-msg { font-size: 12px; margin: 6px 0 0; }
+.karvan-invite-msg.ok { color: #35d07f; }
+.karvan-invite-msg.err { color: #ff8a8a; }
 
 /* --- Karvan videollamada (Fase 1): media P2P sobre el mismo WebRTC del chat --- */
 .karvan-call, .karvan-videos, .karvan-call-bar, .kc-status {
diff --git a/src/models/karvan_model.js b/src/models/karvan_model.js
index baee641..2aa4c74 100644
--- a/src/models/karvan_model.js
+++ b/src/models/karvan_model.js
@@ -72,6 +72,32 @@ module.exports = ({ idleTtlMs = DEFAULT_IDLE_TTL_MS, absTtlMs = DEFAULT_ABS_TTL_
     return publicRoom(room);
   };
 
+  // Fase 2 (invitar): unirse a una sala por su id creando un ESPEJO local (desde un enlace/invitación).
+  // El id es la "capacidad": quien lo tiene puede unirse. Aún NO conecta con la sala del otro nodo
+  // (eso es la señalización cross-device, pendiente); crea la sala local para poder abrir el enlace.
+  const adoptRoom = ({ id, title = "", ttlMinutes } = {}) => {
+    if (!id || typeof id !== "string" || !/^[0-9a-f]{6,64}$/.test(id)) return null;
+    const existing = rooms.get(id);
+    if (existing) return publicRoom(existing);
+    if (rooms.size >= MAX_ROOMS) {
+      const oldest = [...rooms.values()].sort((a, b) => a.createdAt - b.createdAt)[0];
+      if (oldest) destroy(oldest.id);
+    }
+    const createdAt = Date.now();
+    let absMs = absTtlMs;
+    const t = parseInt(ttlMinutes, 10);
+    if (Number.isFinite(t) && t > 0) absMs = Math.min(t * 60000, MAX_ABS_TTL_MS);
+    const room = {
+      id, title: String(title || "").slice(0, 80), createdAt, expiresAt: createdAt + absMs,
+      messages: [], signals: [], members: new Set(), seq: 0, sigSeq: 0, idleTimer: null, absTimer: null,
+    };
+    rooms.set(id, room);
+    room.absTimer = setTimeout(() => destroy(id), absMs);
+    if (room.absTimer.unref) room.absTimer.unref();
+    resetIdle(room);
+    return publicRoom(room);
+  };
+
   const listRooms = () =>
     [...rooms.values()].map(publicRoom).sort((a, b) => b.createdAt - a.createdAt);
 
@@ -138,6 +164,7 @@ module.exports = ({ idleTtlMs = DEFAULT_IDLE_TTL_MS, absTtlMs = DEFAULT_ABS_TTL_
 
   return {
     createRoom,
+    adoptRoom,
     listRooms,
     getRoom,
     postMessage,
diff --git a/src/views/karvan_view.js b/src/views/karvan_view.js
index c63e212..73afd90 100644
--- a/src/views/karvan_view.js
+++ b/src/views/karvan_view.js
@@ -101,7 +101,19 @@ exports.karvanRoomView = (room, messages, params = {}) =>
         input({ type: "hidden", name: "from", value: params.selfId || "" }),
         input({ type: "text", name: "text", id: "karvan-text", placeholder: i18n.karvanSay || "Temporary message…", maxlength: "2000", autocomplete: "off" }),
         button({ type: "submit" }, i18n.karvanSend || "Send")
-      )
+      ),
+      // Fase 2: invitar a un contacto por su feed id → le llega al inbox un enlace a esta sala
+      form({ class: "karvan-invite", method: "POST", action: "/karvan/" + room.id + "/invite" },
+        input({ type: "text", name: "to", placeholder: i18n.karvanInvitePlaceholder || "Invite a contact by @feed-id…", autocomplete: "off", spellcheck: "false" }),
+        button({ type: "submit" }, i18n.karvanInvite || "Invite")
+      ),
+      params.invite === "ok"
+        ? p({ class: "karvan-invite-msg ok" }, i18n.karvanInviteSent || "✓ Invitation sent to their inbox.")
+        : params.invite === "bad"
+        ? p({ class: "karvan-invite-msg err" }, i18n.karvanInviteBad || "✗ That is not a valid @feed-id.")
+        : params.invite === "fail"
+        ? p({ class: "karvan-invite-msg err" }, i18n.karvanInviteFail || "✗ Could not send the invitation.")
+        : ""
     ),
     script({ src: "/js/karvan.js", defer: "defer" })
   );
diff --git a/test/karvan_model.test.js b/test/karvan_model.test.js
index 21f818c..86f033c 100644
--- a/test/karvan_model.test.js
+++ b/test/karvan_model.test.js
@@ -137,6 +137,20 @@ async function test(name, fn) {
     assert.ok(m.getRoom(ids[100]));                      // la última sigue
   });
 
+  await test("adoptRoom: espejo local con id dado, idempotente, rechaza id inválido", () => {
+    const m = makeModel();
+    const id = "abc123def456abc789";
+    const r = m.adoptRoom({ id, title: "espejo" });
+    assert.strictEqual(r.id, id);
+    assert.strictEqual(r.title, "espejo");
+    assert.ok(m.getRoom(id));
+    const again = m.adoptRoom({ id, title: "otro" });       // idempotente
+    assert.strictEqual(again.id, id);
+    assert.strictEqual(m.listRooms().filter((x) => x.id === id).length, 1);
+    assert.strictEqual(m.adoptRoom({ id: "NO-hex!" }), null); // id inválido
+    assert.ok(m.postMessage(id, { from: "a", text: "hola" }), "se puede postear en la adoptada");
+  });
+
   console.log("\n" + passed + " passed, " + failed + " failed");
   process.exit(failed ? 1 : 0);
 })();