# One-time setup
npm install -g @bkey/cli
bkey auth login
bkey auth setup-agent --name "My Agent" --save

# Agent hits any paid API — BKey figures out the rest
bkey proxy GET https://weather-premium.example.com/forecast/SFO

$ bkey proxy GET https://weather-premium.example.com/forecast/SFO
💳 Payment required (x402). Initiating authorization...
✅ Auto-approved. Retrying with payment...
{"city":"SFO","forecast":"sunny","tempF":68}

import { BKey } from '@bkey/sdk';

const bkey = new BKey({
  apiUrl: 'https://api.bkey.id',
  clientId: process.env.BKEY_CLIENT_ID!,
  clientSecret: process.env.BKEY_CLIENT_SECRET!,
});

async function paidFetch(url: string, init?: RequestInit): Promise<Response> {
  let res = await fetch(url, init);
  if (res.status !== 402) return res;

  // Auto-detect: x402 first, then MPP.
  const x402 = res.headers.get('payment-required');
  const mpp = res.headers.get('x-payment-required');

  if (x402) {
    const need = JSON.parse(Buffer.from(x402, 'base64').toString());
    // CAIP-2 network → chain id (e.g. 'eip155:8453' → 8453).
    const parts = String(need.network ?? 'eip155:8453').split(':');
    const chainId = parseInt(parts[parts.length - 1], 10) || 8453;

    const auth = await bkey.authorizeX402Payment({
      amountCents: Math.ceil(Number(need.maxAmountRequired) / 10_000),
      recipientAddress: need.payTo,
      chainId,
      description: need.description,
      resource: need.resource ?? url,
    });

    const signed = auth.status === 'authorized' && auth.authorization
      ? Buffer.from(JSON.stringify(auth.authorization)).toString('base64')
      : (await bkey.pollX402Authorization(auth.authorizationId!)).signedPayload!;

    return fetch(url, {
      ...init,
      headers: { ...init?.headers, 'PAYMENT-SIGNATURE': signed },
    });
  }

  if (mpp) {
    const need = JSON.parse(mpp);
    const auth = await bkey.authorizeMppPayment({
      amountCents: need.amount ?? need.maxAmount,
      currency: need.currency ?? 'USD',
      paymentMethodId: need.paymentMethodId,
      merchantName: need.merchantName,
      description: need.description,
    });

    const sptId = auth.status === 'authorized' && auth.sptId
      ? auth.sptId
      : JSON.parse(
          Buffer.from(
            (await bkey.pollMppAuthorization(auth.authorizationId!)).sptCredential!,
            'base64',
          ).toString(),
        ).sptId;

    // Present the SPT in whatever format the merchant's MPP endpoint expects
    // — most accept it as a JSON body field. See the merchant's MPP docs.
    return fetch(url, {
      ...init,
      method: init?.method ?? 'POST',
      headers: { ...init?.headers, 'Content-Type': 'application/json' },
      body: JSON.stringify({ shared_payment_granted_token: sptId }),
    });
  }

  throw new Error('402 without a payment header we understand');
}

// Now use it like any fetch — agent doesn't know or care about protocols:
const weather = await paidFetch('https://weather-premium.example.com/forecast/SFO');
console.log(await weather.json());

import subprocess, json

# Pure Python — delegate the whole payment loop to the CLI
result = subprocess.run(
    ["bkey", "proxy", "GET", url],
    check=True, capture_output=True, text=True,
)
data = json.loads(result.stdout)

HTTP 402 ─┬─ PAYMENT-REQUIRED header present?  ─────▶ x402 (USDC)
          │
          └─ X-Payment-Required header present? ────▶ MPP (Stripe)

// Check current limits (applies to both protocols)
const { limits } = await bkey.getX402SpendingLimits();

// Wallet address (for x402 on-chain payments)
const wallet = await bkey.getX402Wallet();
console.log(`Wallet: ${wallet.address} (${wallet.asset} on ${wallet.network})`);