Agent Transaction Protocol (ATP)

ATP defines a cryptographically verifiable directed acyclic graph (DAG) model for agent transactions. ATP enables tamper-evident signed causality and auditable lineage across agentic systems by representing each action as a signed node with one or more parent references, assuming verifier access to issuer public keys and the referenced parent nodes. The protocol is designed to be lightweight, transport-independent, and suitable for environments where accountability, provenance, and verifiable history are required.