diff --git a/clients/terminal/render.py b/clients/terminal/render.py
index ecfffcb..2596125 100644
--- a/clients/terminal/render.py
+++ b/clients/terminal/render.py
@@ -25,8 +25,10 @@
 
         if msg_type == "session_sync":
             if self.show_events:
+                sid = msg.get("session_id")
                 profile_id = msg.get("profile_id") or "unknown"
-                self._print(f"[session {msg.get('session_id')[:8]} | profile {profile_id}]", color="bright_black")
+                sid_str = f"{sid[:8]}" if sid else "?"
+                self._print(f"[session {sid_str} | profile {profile_id}]", color="bright_black")
             return
 
         if msg_type == "stream_start":
diff --git a/navi/api/websocket.py b/navi/api/websocket.py
index 01a8fa3..2f84206 100644
--- a/navi/api/websocket.py
+++ b/navi/api/websocket.py
@@ -197,11 +197,19 @@
                 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"})
+            await websocket.send_json({
+                "type": "session_sync",
+                "session_id": session.id,
+                "profile_id": session.profile_id,
+            })
         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"})
+            await websocket.send_json({
+                "type": "session_sync",
+                "session_id": session.id,
+                "profile_id": session.profile_id,
+            })
 
         while True:
             raw = await websocket.receive_text()
diff --git a/tests/clients/test_terminal_ws.py b/tests/clients/test_terminal_ws.py
index 911c1b4..532cb25 100644
--- a/tests/clients/test_terminal_ws.py
+++ b/tests/clients/test_terminal_ws.py
@@ -47,3 +47,25 @@
 
     await asyncio.wait_for(serve(), timeout=10.0)
     assert stop_event.is_set()
+
+
+def test_renderer_session_sync_without_session_id_does_not_crash(capsys) -> None:
+    """Regression: session_sync with no session_id must not crash the renderer.
+
+    The server used to send {"type": "session_sync"} without session_id, which
+    made render.py do None[:8]. The renderer must tolerate a missing id.
+    """
+    renderer = Renderer(show_events=True)
+    renderer.render({"type": "session_sync"})  # no session_id / profile_id
+    out = capsys.readouterr().out
+    assert "[session ? | profile unknown]" in out
+
+
+def test_renderer_session_sync_with_session_id(capsys) -> None:
+    """When session_id/profile_id are present they render in the header."""
+    renderer = Renderer(show_events=True)
+    renderer.render(
+        {"type": "session_sync", "session_id": "abcdef1234567890", "profile_id": "navi_code"}
+    )
+    out = capsys.readouterr().out
+    assert "[session abcdef12 | profile navi_code]" in out