Constant MAX_WIRE_BYTES 

pub const MAX_WIRE_BYTES: usize = _; // 1_048_576usize

One message’s bound. A call has no participant limit; a status names each person (64 bytes) and the people whose pictures it shows (64 each), so this carries well over a thousand of them, and a Command::Pictures answer always at least one whole picture of the largest layer (MAX_PICTURE_BYTES in base64).