diff --git a/src/dashboard/app.py b/src/dashboard/app.py
index a705c18..cc2d3de 100644
--- a/src/dashboard/app.py
+++ b/src/dashboard/app.py
@@ -410,11 +410,17 @@ app.include_router(cascade_router)
 
 @app.websocket("/ws")
 async def ws_redirect(websocket: WebSocket):
-    """Catch stale /ws connections and close cleanly."""
+    """Catch stale /ws connections and close cleanly.
+
+    websockets 16.0 dropped the legacy ``transfer_data_task`` attribute,
+    so calling ``websocket.close()`` after accept triggers an
+    AttributeError.  Use the raw ASGI send instead.
+    """
     await websocket.accept()
     try:
         await websocket.close(code=1008, reason="Deprecated endpoint")
     except AttributeError:
+        # websockets >= 16.0 — close via raw ASGI message
         await websocket.send({"type": "websocket.close", "code": 1008})