@xyncpay-org/ap2-typescript-sdk

TypeScript SDK for the Agent Payment Protocol v2 (AP2). Provides mandate construction, SD-JWT-VC credential issuance and verification, constraint evaluation, and OpenID4VP transaction_data binding for autonomous AI agent payment flows.

At a glance

| | | |---|---| | Package | @xyncpay-org/ap2-typescript-sdk | | License | MIT | | Protocol | AP2 (Agent Payment Protocol v2) | | Credential format | SD-JWT-VC with KB-SD-JWT key binding | | Cryptography | @noble/curves (P-256, Ed25519), JOSE for JWK handling | | Node | >= 22 | | Type definitions | Built-in TypeScript declarations |

Installation

npm install @xyncpay-org/ap2-typescript-sdk

Overview

AP2 defines a mandate-based authorization model for agent payments. An agent presents a verifiable mandate (an SD-JWT-VC credential) that encodes spending constraints. The merchant verifies the mandate and the key binding proof before accepting a payment instruction.

This SDK provides:

• Mandate construction -- build and sign SD-JWT-VC payment mandates with configurable selective disclosure
• Mandate verification -- verify issuer signature, holder binding, and constraint satisfaction
• Constraint evaluation -- evaluate AP2 constraint expressions against payment parameters
• OpenID4VP binding -- construct and verify transaction_data objects for presentation flows
• Type definitions -- complete TypeScript types for all AP2 protocol objects

Quick Start

import { buildMandate, verifyMandate } from "@xyncpay-org/ap2-typescript-sdk";

// Build a mandate
const mandate = await buildMandate({
  issuerKey: issuerJwk,
  holderKey: holderPublicJwk,
  claims: {
    spendingCap: "100000000",   // 100 USDC in smallest units
    perTransactionLimit: "10000000",
    currency: "USDC",
    chain: "base",
  },
});

// Verify a presented mandate with key binding
const result = await verifyMandate(mandate, {
  issuerPublicKey: issuerPublicJwk,
  nonce: requestNonce,
});

Architecture

src/
  index.ts           Public API re-exports
  mandate/
    build.ts         SD-JWT-VC mandate construction
    verify.ts        Mandate verification and constraint checking
  constraints/
    evaluate.ts      AP2 constraint expression evaluator
  openid4vp/
    transaction.ts   transaction_data binding for OpenID4VP
  types.ts           AP2 protocol type definitions

See docs/adr/ for architecture decisions.

License

MIT. See LICENSE.