Create instant payment links for agents.

import {
  createPayRequest,
  payPayRequestWithCode,
  createPrivateKeySigner,
  generatePaymentCode,
} from '@relai-fi/x402';

const config = { facilitatorUrl: 'https://relai.fi/facilitator' };

// ── Merchant side ──────────────────────────────────────────
const req = await createPayRequest(config, {
  to:          '0xMerchantWallet',
  amount:      5_000_000,       // $5.00 USDC (micro-units)
  network:     'base-sepolia',
  description: 'Order #42',
});
console.log('Invoice code:', req.code); // "SHOP1234"

// ── Buyer side ─────────────────────────────────────────────
// Buyer already has a payment code (generated earlier by an agent)
const result = await payPayRequestWithCode(
  config,
  'SHOP1234',   // merchant's invoice code
  'MYBLIK78',   // buyer's pre-generated payment code
);

console.log('Success:', result.success);
console.log('Explorer:', result.explorerUrl);

// If the code was worth more than the invoice, you get change back:
if (result.changeCode) {
  console.log('Change code:', result.changeCode);
  // Pass this to the buyer — they can use it for the next purchase
}

// Default: change returned as a new payment code (no wallet needed)
const result = await payPayRequestWithCode(config, requestCode, paymentCode);
// result.changeCode = "RESZTA8"  — buyer can use this for the next payment

// Option B: change returned atomically to buyer's wallet (on-chain)
const result2 = await payPayRequestWithCode(config, requestCode, paymentCode, {
  returnChange: 'wallet',
});

// Strict mode: throw if code value ≠ invoice amount exactly
const result3 = await payPayRequestWithCode(config, requestCode, paymentCode, {
  allowOverpayment: false,
});

// GET /facilitator/pay-requests/events
// Content-Type: text/event-stream

const es = new EventSource(
  'https://api.relai.fi/facilitator/pay-requests/events',
  { headers: { 'X-Service-Key': 'sk_live_...' } }
);

es.onmessage = (e) => {
  const { code, status, payTxHash, explorerUrl } = JSON.parse(e.data);
  if (status === 'paid') {
    console.log('Paid!', explorerUrl);
    es.close();
  }
};

curl -X POST https://api.relai.fi/facilitator/pay-requests \
  -H "X-Service-Key: sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "to": "0xYourMerchantWallet",
    "amount": 5.00,
    "network": "base-sepolia",
    "description": "Invoice #42",
    "ttl": 3600
  }'

{
  "code": "MW78SGTW",
  "expiresIn": 3600,
  "payUrl": "https://relai.fi/pay#MW78SGTW"
}