casm-agent

Agent wrapper for automatic x402 payment handling in CASM (Cronos Agentic Service Mesh).

Installation

npm install casm-agent

Quick Start

const { createCASMAgent } = require('casm-agent');

// Create agent with wallet credentials
const agent = createCASMAgent({
  privateKey: '0x...your_private_key',
  walletAddress: '0x...your_wallet',
  onPayment: (payment) => {
    console.log(`Paid ${payment.amount} to ${payment.recipient}`);
  },
});

// Make requests - payments happen automatically!
const response = await agent.fetch('https://api.provider.com/whale-alerts');
const data = await response.json();
console.log(data);

How It Works

1. Agent makes request → Provider returns 402 Payment Required
2. Agent automatically signs EIP-3009 payment → Retries with signature
3. Provider verifies → Returns data
4. Agent never even knows payment happened! 🎉

┌─────────┐      ┌──────────┐      ┌───────────┐
│  Agent  │─────▶│ Provider │─────▶│ x402      │
│         │◀─402─│          │◀─────│ Facilitator│
│         │─sig─▶│          │      │           │
│         │◀─200─│          │      │           │
└─────────┘      └──────────┘      └───────────┘

API Reference

createCASMAgent(options)

Create a payment-enabled agent.

| Option | Type | Required | Description | |--------|------|----------|-------------| | privateKey | string | ✅ | Agent's private key | | walletAddress | string | ✅ | Agent's wallet address | | maxRetries | number | | Max payment attempts (default: 1) | | onPayment | function | | Called after each payment | | onError | function | | Called on payment errors |

agent.fetch(url, options)

Fetch wrapper with automatic 402 handling.

// Works like regular fetch
const response = await agent.fetch('https://api.example.com/data', {
  method: 'GET',
  headers: { 'Content-Type': 'application/json' },
});

agent.getPaymentHistory()

Get array of all payments made.

const history = agent.getPaymentHistory();
// [{ timestamp, url, amount, recipient, nonce }, ...]

agent.getTotalSpent()

Get total amount spent (as BigInt).

const total = agent.getTotalSpent();
console.log(`Total spent: ${total / 1000000n} USDC`);

signPayment(params)

Sign an EIP-3009 authorization directly.

const { signPayment } = require('casm-agent');

const signature = await signPayment({
  privateKey: '0x...',
  from: '0x...sender',
  to: '0x...recipient',
  amount: '50000',
  nonce: 'abc123...',
  deadline: Math.floor(Date.now() / 1000) + 300,
  tokenAddress: '0x...USDC',
  chainId: 338,
});

Integration with AI Agents

// Example with a hypothetical AI agent framework
const agent = createCASMAgent({
  privateKey: process.env.AGENT_PRIVATE_KEY,
  walletAddress: process.env.AGENT_ADDRESS,
});

// AI agent can now use paid APIs transparently
async function getWhaleData() {
  const res = await agent.fetch('https://whale-tracker.casm/api/alerts');
  return res.json();
}

License

MIT