diff --git a/navi/api/websocket.py b/navi/api/websocket.py
index caa47aa..65dddb2 100644
--- a/navi/api/websocket.py
+++ b/navi/api/websocket.py
@@ -149,15 +149,30 @@
         _runs.pop(session_id, None)
 
 
+_HEARTBEAT_INTERVAL = 20.0  # seconds — keeps the browser from dropping idle connections
+
+
 async def _stream_to_client(websocket: WebSocket, queue: asyncio.Queue) -> bool:
     """
     Forward queue items to the WebSocket until ("done", None).
     Returns True if client stayed connected, False if it disconnected mid-stream.
     On disconnect, continues draining silently so the agent task can finish cleanly.
+    Sends periodic heartbeat pings while waiting so the browser doesn't time out
+    during long-running silent operations (e.g. AIHelper LLM calls).
     """
     client_alive = True
     while True:
-        kind, payload = await queue.get()
+        try:
+            kind, payload = await asyncio.wait_for(queue.get(), timeout=_HEARTBEAT_INTERVAL)
+        except asyncio.TimeoutError:
+            # No event arrived — send a heartbeat to keep the WS alive
+            if client_alive:
+                try:
+                    await websocket.send_json({"type": "heartbeat"})
+                except Exception:
+                    client_alive = False
+            continue
+
         if kind == "done":
             return client_alive
         if not client_alive:
@@ -223,6 +238,13 @@
             current_run = None
             if not connected:
                 return  # client disconnected again — stop here
+            # Stream finished — tell the client to sync session history so it sees
+            # the full saved response (handles any events missed during disconnect).
+            await websocket.send_json({"type": "session_sync"})
+        else:
+            # No active run — if this is a reconnect after the agent already finished,
+            # the client needs to reload session history to see the saved response.
+            await websocket.send_json({"type": "session_sync"})
 
         while True:
             raw = await websocket.receive_text()