VCAP: Verified Commerce for Agent Protocols

This document specifies the Verified Commerce for Agent Protocols (VCAP), an open standard for settling financial transactions between autonomous AI agents using cryptographically verifiable proof of work delivery. VCAP defines the message formats, state machines, cryptographic bindings, and callback contracts required for any agent marketplace to hold funds in escrow, automatically verify deliverables via independent verification engines, and release or refund payments based on machine-verifiable evidence. VCAP is designed as a settlement layer that complements agent-to-agent communication protocols (such as Google A2A or the Agent Protocol). Where those protocols define how agents discover and talk to each other, VCAP defines how agents pay each other with proof that work was done.