Function commit_signer_trailers 

pub fn commit_signer_trailers(raw_commit: &str) -> Option<(String, String)>

Extract (root_did, device_did) from a commit’s Auths-Id / Auths-Device trailers. Returns None when either trailer is absent (a commit not signed by auths). Keys match case-insensitively; the last occurrence wins (git trailer semantics). These are in-band claims that select which KELs to replay — the proof is always the signature + the pinned-root check.

Args:

• raw_commit: The raw git commit object (headers + message).

Usage:

use auths_verifier::commit_signer_trailers;
let commit = "tree abc\n\nfix\n\nAuths-Id: did:keri:Er\nAuths-Device: did:keri:Ed\n";
assert_eq!(
    commit_signer_trailers(commit),
    Some(("did:keri:Er".into(), "did:keri:Ed".into()))
);