Protocol Landscape

The agentic commerce ecosystem as of March 2026 includes over twenty protocols spanning payments, commerce, identity, and authorization. The Agent Legal Context (ALC) protocol complements all of them by providing the missing legal layer.

Payment Protocols

MPP (Machine Payments Protocol) -- Stripe and Tempo Labs. IETF Internet-Draft. Uses HTTP 402 challenge-response for machine-to-machine payments. Settles on Tempo (stablecoin rail). The opaque field in the 402 challenge and the 32-byte TIP-20 memo field are the natural embedding points for contentHash.

x402 (Payment Protocol) -- Coinbase. Lightweight HTTP 402-based payment for API access. Response headers and payment metadata carry the contentHash.

Commerce Protocols

ACP (Agentic Commerce Protocol) -- Stripe and OpenAI. Apache 2.0, open source. Multi-step checkout lifecycle with Shared Payment Tokens for agent spending authorization. Checkout session metadata carries the contentHash. Terms acceptance can be a pre-completion step.

UCP (Universal Commerce Protocol) -- Google. Cryptographic mandate model where merchants embed transaction terms signed by the agent or user wallet. The closest existing protocol to explicit terms acceptance, but consent is declarative, not enforced. ALC provides the enforcement layer that UCP explicitly declares out-of-scope.

AP2 (Agent Payments Protocol) -- Google. Three-mandate model (cart, intent, payment) with Verifiable Digital Credentials (VDCs). All three mandates can reference contentHash. The multi-party evidence structure maps directly to IntegraRecord parties.

Identity and Authorization Protocols

Visa TAP (Token-Agent-Principal) -- Three-signature model for agent authorization: agent intent, consumer recognition, payment container. PKI-based agent identity. The agent intent signature payload is the natural embedding point for contentHash.

Mastercard Agent Pay -- Agentic Tokens for agent identity, KYA (Know Your Agent) registration, and Verifiable Intent via SD-JWT. Agent registration and token metadata can reference IntegraRecords.

A2A (Agent-to-Agent) -- Google. Agent Cards for agent discovery and task-based interaction. Agent Card extensions carry contentHash and API URL. Task metadata binds specific interactions to terms.

MCP (Model Context Protocol) -- Anthropic. Tool definitions for model-to-service interaction. ALC operations can be exposed as MCP tools, making legal context available to any MCP-compatible model.

How ALC Relates

The Agent Legal Context protocol uses existing extension mechanisms in each protocol. No core specification changes are required. The protocol sits alongside the commerce layer, not inside it:

APPLICATION LAYER
  AI agents, chatbots, autonomous services

COMMERCE PROTOCOL LAYER
  MPP - ACP - UCP - x402 - AP2 - Visa TAP

AGENT LEGAL CONTEXT (ALC) LAYER       <-- here
  Discovery - Terms - Acceptance
  Records - Disputes - Compliance

SETTLEMENT LAYER
  Tempo - Base - Ethereum - Visa

See Integration Details for protocol-by-protocol integration tables, or Gap Analysis for the complete capability matrix.