Function pair_transcript 

pub fn pair_transcript(
    role: &[u8],
    proto: u32,
    agent: &str,
    wid: &str,
    did: &str,
    phone_pubkey: &str,
    nonce: &[u8],
) -> Vec<u8> 

Build the enrollment transcript bound to every field that scopes the proof, using FIXED-length (u32_le) length-prefixing so no field boundary is ambiguous (mirrors bridge::envelope::signing_bytes). The token is NOT included — it is the HMAC key in pair_proof, never in the signed bytes.