@zanii/x402

Bind a Zanii payment receipt to its on-chain settlement. recordPayment proves who paid whom; the rail (x402 / AP2) settles on-chain. This closes the loop: given the settlement tx a receipt references, verify it actually settled to the stated recipient — so a payment proof is trustworthy, not just recorded.

npm install @zanii/x402 @zanii/payments @zanii/sdk

Chain reads are injected, so the core is testable offline; a zero-dependency JSON-RPC fetcher is included for any EVM chain (Base included).

Usage

import { buildX402Payment, verifySettlement, jsonRpcTxFetcher } from '@zanii/x402';

// build + record the payment (money handled correctly by @zanii/payments):
const p = buildX402Payment({ txHash, amount: '49.99', currency: 'USD', to: merchant, chainId: 8453 });
await agent.recordPayment({ rail: p.rail, reference: p.reference, details: p });

// later — verify the settlement actually happened:
const check = await verifySettlement(
  { txHash, to: merchant, minValue: 49_990_000n },  // e.g. 49.99 USDC (6dp)
  jsonRpcTxFetcher('https://mainnet.base.org'),
);
if (check.ok) { /* the receipt's tx settled to the right party */ }

verifySettlement checks the tx exists, succeeded, went to the recipient, optionally came from the sender, and moved at least minValue.

Native vs ERC-20. minValue checks the transaction's native value. For token transfers (e.g. USDC), pass a TxFetcher that reads the ERC-20 Transfer log and maps it onto OnChainTx — recipient/status/existence checks work either way.

Changelog

• 0.1.0 — initial release: verifySettlement, buildX402Payment, jsonRpcTxFetcher.

License

Apache-2.0.