Function upgrade 

pub async fn upgrade(
    ws: WebSocketUpgrade,
    __arg1: State<Arc<TransportState>>,
    __arg2: ConnectInfo<SocketAddr>,
    headers: HeaderMap,
    uri: Uri,
) -> Response

Take the upgrade and give the connection its own task.

Both tungstenite limits are raised to the one inbound cap: the frame limit (16 MiB by default here, exactly the cap) and the message limit (64 MiB by default, lowered to the cap so one message cannot be several frames past what a single frame may be). A frame the cap refuses never reaches super::frame; anything under it does, and a dictation payload a shade too big is refused there with its reason rather than tearing the socket.