Disable afk log-out/always stay logged-in? (3.3.5)

Does the client auto-log send a packet that’s different than regular log-out?

I was reading this and there’s mention of stuff like SMSG_LOGOUT_CANCEL_ACK and CMSG_LOGOUT_REQUEST; maybe if the client sends a afk log-out notice or something to the server, the server can override or send something different (like un-afk player)?