🛰️ M2MCent SDK — x402 Payment Wrapper for AI Agents

Ultra-lightweight x402 payment interceptor for AI Agents and MCP Servers. Monetize any API in 3 lines of code.

🚀 Quick Start

bash

npm install m2mcent-sdk

typescript

import { X402Handler } from 'm2mcent-sdk';

const x402 = new X402Handler({
  rpcUrl: 'https://mainnet.base.org',
  privateKey: process.env.RELAYER_PRIVATE_KEY!,
  recipient: process.env.TREASURY_ADDRESS!
});

// Protect any Express endpoint with a USDC paywall
app.post('/api/analyze', x402.requirePayment("100000"), (req, res) => {
  res.json({ result: "Premium analysis complete", receipt: req.paymentTx });
});

📐 How It Works

M2MCent implements the x402 Payment Protocol — a machine-native payment standard inspired by HTTP 402:

Agent requests a protected endpoint
Server responds with 402 Payment Required + payment metadata (Base64 encoded)
Agent signs an EIP-712 typed data authorization (gasless for the payer)
Server settles atomically on-chain via the M2MCent Escrow contract
Agent receives the premium response + transaction receipt

Agent ──► API Server ──► 402 + metadata
Agent ◄── signs EIP-712 authorization
Agent ──► API Server + Payment-Signature header
          └──► Escrow.settle() on Base L2
Agent ◄── Premium Response + tx hash

⚙️ Configuration

Parameter	Description	Required
`rpcUrl`	Base Mainnet RPC endpoint	✅
`privateKey`	Relayer wallet private key (for settlement)	✅
`recipient`	Treasury address to receive payments	✅

🔒 Security

Non-custodial: Funds flow directly from payer → treasury via on-chain escrow
Gasless for payers: Uses EIP-3009 transferWithAuthorization (USDC native)
Zero-Leak: No agent data is retained after settlement
Atomic: Payment and service delivery happen in a single request cycle

🌐 Network Details

Parameter	Value
Network	Base Mainnet (Chain ID: 8453)
USDC Contract	`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`
Escrow Contract	`0xf3c3416A843d13C944554A54Ac274BB7fF264BcC`
Settlement	Atomic, sub-second finality

🧩 MCP Server Integration

Perfect for Model Context Protocol servers:

typescript

import express from 'express';
import { X402Handler } from 'm2mcent-sdk';

const app = express();
const x402 = new X402Handler({
  rpcUrl: process.env.BASE_RPC_URL!,
  privateKey: process.env.RELAYER_PRIVATE_KEY!,
  recipient: process.env.TREASURY_ADDRESS!
});

// Any MCP tool endpoint becomes monetizable
app.post('/api/tools/analyze', x402.requirePayment("50000"), async (req, res) => {
  const result = await runMCPTool(req.body);
  res.json({ ...result, paymentTx: req.paymentTx });
});