The proliferation of autonomous software agents necessitates rigorous frameworks for establishing secure and verifiable agent-to-agent (A2A) interactions, particularly when such agents are instantiated as non-human identities(NHIs). We extend the A2A paradigm [1 , 2] by introducing a cryptographically grounded mechanism for lineage verification, wherein the provenance and evolution of NHIs are anchored in append-only Merkle tree structures modeled after Certificate Transparency (CT) logs. Unlike traditional A2A models that primarily secure point-to-point interactions, our approach enables both agents and external verifiers to cryptographically validate multi-hop provenance, thereby ensuring the integrity of the entire call chain. A federated proof server acts as an auditor across one or more Merkle logs, aggregating inclusion proofs and consistency checks into compact, signed attestations that external parties can verify without access to the full execution trace. In parallel, we augment the A2A agent card to incorporate explicit identity verification primitives, enabling both peer agents and human approvers to authenticate the legitimacy of NHI representations in a standardized manner. Together, these contributions establish a cohesive model that integrates identity attestation, lineage verification, and independent proof auditing, thereby advancing the security posture of inter-agent ecosystems and providing a foundation for robust governance of NHIs in regulated environments such as FedRAMP.