Function lookup_credential_attach 

pub fn lookup_credential_attach<'a, EF, V, LF>(
    token_phase: CredentialAttachTokenPhase<'a, EF, V, LF>,
    presented_identity: PresentedIdentity<'a, EF, V, LF>,
    binding: &BindingState,
    request: &CredentialAttachRequest,
    secret_proof: AttachSecretProof,
) -> CredentialAttachLookupResult<'a, EF>

Applies credential-attach token lookup, tombstone precedence, verifier order, and ordinary live-authority checks.

secret_proof is computed against the live receipt verifier when the phase is CredentialAttachTokenPhase::LiveReceipt, and against the current live member for CredentialAttachTokenPhase::NoMatch. Provenance phases have no verifier and ignore it by construction of their result path.