Proof of agreement

Every payment a connector handles carries one proof: the hash of the record the buyer and the seller agreed to. This page defines the terms the rest of the documentation uses.

The Agentic Transaction Record (ATR)Copy Anchor Link

The Agentic Transaction Record (ATR) is the agreement's record: one JSON document the seller serves at an https link. Its bytes are written once, in a fixed order:

1. atrVersion, the format marker;
2. id, a per-transaction identifier;
3. the binding's slot, which ties the record to this payment (on x402, the x402 slot records every option the challenge offers, exactly as issued, and the request it answers);
4. the parties' slots, each written as the exact bytes received.

Here is the ATR the seller door stores for vector CV1: 506 bytes, shown as they are.

{"atrVersion":"1","id":"6f1c2b0e-8d4a-4c3b-9e2f-1a7d5c9b3e50","x402":{"accepts":[{"scheme":"exact","network":"eip155:84532","amount":"10000","asset":"0x036CbD53842c5426634e7929541eC2318f3dCF7e","payTo":"0x209693Bc6afc0C5328bA36FaF03C514EF312287C","maxTimeoutSeconds":60,"extra":{"name":"USDC","version":"2"}}],"request":{"method":"GET","path":"/v1/report","query":"","bodyDigest":"0xe3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"}},"terms":"Pay 10000 base units of USDC for one report."}

The seller door does not require, supply or read any party content. What goes into content is the parties' choice: terms, a checkout, a signed quote, a credential. The door carries it as given.

The ATR hash (H)Copy Anchor Link

The ATR hash (H) is SHA-256 over the ATR's exact bytes, written 0x and 64 lowercase hex digits. The bytes are never canonicalised or re-serialised: the hash is over the bytes written, and the buyer hashes the bytes it fetches.

import { createHash } from "node:crypto";
import { VECTORS } from "@integraledger/agentic-connectors";

const stored = VECTORS["CV1"]!.steps[0]!.stored!;
const h = `0x${createHash("sha256").update(stored.bytes, "utf8").digest("hex")}`;
console.log(Buffer.byteLength(stored.bytes, "utf8"), h);
console.log(h === stored.sha256);

506 0x3c2394624c8c9a61ebaf7d8750a6f9ac21bf73e6369b7c0b64c83e34509cc3d3
true

The Legal Context Protocol (LCP)Copy Anchor Link

The Legal Context Protocol (LCP) is the pattern these packages serve: the payment carries H, so paying is agreeing to that exact record. Whatever the protocol and rail, the pattern is the same:

1. The seller assembles the ATR, stores it where the buyer can fetch it, and puts H and the link in the payment request.
2. The buyer fetches the ATR, hashes the bytes it received, and compares the result with H before it signs anything.
3. The buyer's payment carries H, in the field the protocol or rail provides.
4. The seller checks that the payment carries the H it issued for this request.

Pairings and bindingsCopy Anchor Link

A pairing is a payment protocol, scheme and rail combination, such as x402/exact/eip155/eip3009. The seller door accepts every pairing @integraledger/lcp registers; the pairings reference lists them.

A binding is how H rides in a pairing's payment: the field its specification defines. On x402/exact/eip155/eip3009, H is the EIP-3009 authorization's nonce, which the payer signs and which lands on chain in the token contract's AuthorizationUsed event. On a card payment, nothing the buyer signs carries H, and the record says so.

Each pairing has a pattern: how it carries H, and what a record of it proves. The door returns the pattern with every record, so a record never claims more than its pairing shows.

The buyer gateCopy Anchor Link

The buyer gate is the buyer-side check that compares the served bytes with H before anything is signed. A buyer whose gate finds a mismatch, or cannot fetch the ATR, does not pay. That is why the seller door writes the ATR to the seller's storage before issue answers: a storage failure means no challenge goes out. The buyer's side lives in integra-agentic-terms.

Delivery, not storageCopy Anchor Link

The ATR lives in the seller's storage, at the link issue returns. The buyer keeps its own copy. The door keeps hashes and the few facts its check needs, and holds the bytes only while assembling them.