Constant MAX_CLIENT_MESSAGE_BYTES 

const MAX_CLIENT_MESSAGE_BYTES: usize = _ /* 16_777_226usize */;

The largest message a client may send.

The cap is abuse’s, not a prompt’s. A command carries a session’s whole prompt text, and 16 MiB is the bound the socket has always allowed; the dictation payload’s 16 KiB is a frame size, and applying it to every inbound message tore the connection on a large prompt - with no reply on a prompt, the loss was silent (measured on the dev stack).