fix: resolve WebSocket crashes from websockets 16.0 incompatibility (#97)

The /ws redirect handler crashed with AttributeError because websockets
16.0 removed the legacy transfer_data_task attribute. The /swarm/live
endpoint could also error on early client disconnects during accept.

Co-authored-by: Alexander Payne <apayne@MM.local>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/dashboard/app.py

@@ -545,9 +545,17 @@ async def ws_redirect(websocket: WebSocket):
     an endpoint.  Stale browser tabs retry forever, spamming 403 errors.
     Accept the connection and immediately close with a policy-violation
     code so the client stops retrying.
+
+    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()
-    await websocket.close(code=1008, reason="Use /swarm/live instead")
+    try:
+        await websocket.close(code=1008, reason="Use /swarm/live instead")
+    except AttributeError:
+        # websockets >= 16.0 — close via raw ASGI message
+        await websocket.send({"type": "websocket.close", "code": 1008})
 
 
 @app.get("/", response_class=HTMLResponse)

src/dashboard/routes/swarm.py

@@ -409,7 +409,11 @@ def submit_bid(bid: BidRequest):
 @router.websocket("/live")
 async def swarm_live(websocket: WebSocket):
     """WebSocket endpoint for live swarm event streaming."""
-    await ws_manager.connect(websocket)
+    try:
+        await ws_manager.connect(websocket)
+    except Exception as exc:
+        logger.warning("WebSocket accept failed: %s", exc)
+        return
     try:
         while True:
             data = await websocket.receive_text()