feat(webui): polish chat layout and titles

Align the WebUI sidebar and chat chrome with the updated design, and generate WebUI session titles asynchronously without blocking turns.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/channels/test_websocket_channel.py

@@ -167,6 +167,40 @@ def test_issue_route_secret_matches_empty_secret() -> None:
     assert _issue_route_secret_matches(Headers([("Authorization", "Bearer anything")]), "") is True
 
 
+@pytest.mark.asyncio
+async def test_webui_message_envelope_marks_inbound_metadata(bus: MagicMock) -> None:
+    channel = _ch(bus)
+    conn = MagicMock()
+    conn.remote_address = ("127.0.0.1", 50123)
+
+    await channel._dispatch_envelope(
+        conn,
+        "webui-client",
+        {"type": "message", "chat_id": "chat-1", "content": "hello", "webui": True},
+    )
+
+    msg = bus.publish_inbound.await_args.args[0]
+    assert msg.channel == "websocket"
+    assert msg.chat_id == "chat-1"
+    assert msg.metadata["webui"] is True
+    assert msg.metadata["_wants_stream"] is True
+
+
+@pytest.mark.asyncio
+async def test_plain_websocket_message_does_not_mark_webui(bus: MagicMock) -> None:
+    channel = _ch(bus)
+    conn = MagicMock()
+
+    await channel._dispatch_envelope(
+        conn,
+        "custom-client",
+        {"type": "message", "chat_id": "chat-1", "content": "hello"},
+    )
+
+    msg = bus.publish_inbound.await_args.args[0]
+    assert "webui" not in msg.metadata
+
+
 @pytest.mark.asyncio
 async def test_send_delivers_json_message_with_media_and_reply() -> None:
     bus = MagicMock()
@@ -306,6 +340,25 @@ async def test_send_turn_end_emits_turn_end_event() -> None:
     assert body == {"event": "turn_end", "chat_id": "chat-1"}
 
 
+@pytest.mark.asyncio
+async def test_send_session_updated_emits_session_updated_event() -> None:
+    bus = MagicMock()
+    channel = WebSocketChannel({"enabled": True, "allowFrom": ["*"]}, bus)
+    mock_ws = AsyncMock()
+    channel._attach(mock_ws, "chat-1")
+
+    await channel.send(OutboundMessage(
+        channel="websocket",
+        chat_id="chat-1",
+        content="",
+        metadata={"_session_updated": True},
+    ))
+
+    mock_ws.send.assert_awaited_once()
+    body = json.loads(mock_ws.send.await_args.args[0])
+    assert body == {"event": "session_updated", "chat_id": "chat-1"}
+
+
 @pytest.mark.asyncio
 async def test_send_non_connection_closed_exception_is_raised() -> None:
     bus = MagicMock()