Private agents.Zero knowledge.

import { createWalletClient, custom, toHex } from 'viem';
import { robinhood } from 'viem/chains';

// 1. The resource answers 402 Payment Required with its price
const offer = await fetch('/api/x402/premium');
const [requirements] = (await offer.json()).accepts;

// 2. Sign an EIP-3009 USDG authorization in the wallet
const wallet = createWalletClient({ chain: robinhood, transport: custom(window.ethereum) });
const [from] = await wallet.requestAddresses();
const authorization = {
  from,
  to: requirements.payTo,
  value: BigInt(requirements.maxAmountRequired),
  validAfter: 0n,
  validBefore: BigInt(Math.floor(Date.now() / 1000) + 120),
  nonce: toHex(crypto.getRandomValues(new Uint8Array(32))),
};
const signature = await wallet.signTypedData({
  account: from,
  domain: { name: 'Global Dollar', version: '1', chainId: 4663, verifyingContract: requirements.asset },
  types: { TransferWithAuthorization },
  primaryType: 'TransferWithAuthorization',
  message: authorization,
});

// 3. Retry with X-PAYMENT; the facilitator settles on Robinhood Chain
const paid = await fetch('/api/x402/premium', { headers: { 'X-PAYMENT': encodePayment(signature, authorization) } });