x402 Payments

# (a) Initial request with no API key -> 402 with the PAYMENT-REQUIRED header
curl -i -X GET "https://api.webacy.com/addresses/0x742d35Cc6634C0532925a3b844Bc454e4438f44e?chain=eth"

# Response headers include:
#   HTTP/1.1 402 Payment Required
#   PAYMENT-REQUIRED: eyJkZXBvc2l0QWRkcmVzcyI6IjB4Li4uIiwiYW1vdW50IjoiNTAwMDAwIn0=

# (b) Decode the base64 challenge to read the deposit address and amount
echo "eyJkZXBvc2l0QWRkcmVzcyI6IjB4Li4uIiwiYW1vdW50IjoiNTAwMDAwIn0=" | base64 -d
# { "depositAddress": "0x...", "amount": "500000" }

# ...pay the amount in USDC on Base to depositAddress...

# (c) Retry the same request with your signed payment proof
curl -i -X GET "https://api.webacy.com/addresses/0x742d35Cc6634C0532925a3b844Bc454e4438f44e?chain=eth" \
  -H "payment-signature: YOUR_SIGNED_PAYMENT"

# Response now returns the data plus:
#   x-credit-token: <token>
#   x-credit-balance-cu: <remaining CUs>

// Illustrative flow. The pay() step is a placeholder for signing the payment
// with your Base wallet or an x402 client library (see the note below).
const url =
  'https://api.webacy.com/addresses/0x742d35Cc6634C0532925a3b844Bc454e4438f44e?chain=eth';

// (a) Initial request with no API key -> 402 with the PAYMENT-REQUIRED header
let res = await fetch(url);

if (res.status === 402) {
  // (b) Decode the base64 challenge to read the deposit address and amount
  const challenge = JSON.parse(
    atob(res.headers.get('PAYMENT-REQUIRED'))
  );
  console.log(challenge); // { depositAddress: '0x...', amount: '500000' }

  // ...pay challenge.amount in USDC on Base to challenge.depositAddress,
  //    then produce a signed payment proof...
  const paymentSignature = await pay(challenge);

  // (c) Retry the same request with your signed payment proof
  res = await fetch(url, {
    headers: { 'payment-signature': paymentSignature },
  });
}

const data = await res.json();
console.log(res.headers.get('x-credit-token'));      // save this for later requests
console.log(res.headers.get('x-credit-balance-cu')); // remaining balance