Function challenge_sign_bytes_with_stream 

pub fn challenge_sign_bytes_with_stream(
    challenge: &[u8],
    ts: i64,
    session_context: &[u8],
    stream_id: &[u8],
    stream_seq: i64,
) -> Vec<u8> 

v1.1 stream-bound challenge signable bytes. Layout: challenge || big-endian uint64(ts) || [session_context] || stream_id || big-endian int64(stream_seq).

session_context may be empty or 32 bytes; stream_id may be empty (no stream binding) or 32 bytes. When stream_id is empty, stream_seq is ignored.