agentbase

Base primitives for AI agent infrastructure. Two things in one package:

• Wallet — USDC client for Base, Ethereum, Polygon (balance, allowance, format helpers)
• Gateway — RFC 9421 Ed25519 signature verification middleware for Express and Fastify

Part of the ArisPay agent toolkit.

Install

npm install agentbase

Wallet

import { AgentWallet } from 'agentbase/wallet';

const wallet = new AgentWallet({ chain: 'base' });

const balance = await wallet.getBalance('0xUserAddress');
console.log(wallet.formatUSDC(balance));   // "12.34"

const allowance = await wallet.getAllowance('0xUserAddress', '0xSpenderAddress');

const raw = wallet.parseUSDC('12.34');     // bigint, 6-decimal units

| Chain | USDC contract | |-------|---------------| | ethereum | 0xA0b86991...eB48 | | base | 0x83358...02913 | | polygon | 0x3c499c...c3359 |

Gateway — Express

import express from 'express';
import { agentGateway } from 'agentbase/gateway/express';

const app = express();

app.use(agentGateway({
  getPublicKey: async (keyId) => lookupKey(keyId),
  maxAgeSeconds: 480,
  allowedTags: ['agent-payer-auth'],
}));

app.post('/checkout', (req, res) => {
  res.json({ agent: req.agent });   // populated on verified request
});

Gateway — Fastify

import fastify from 'fastify';
import { agentGatewayHook } from 'agentbase/gateway/fastify';

const app = fastify();

app.addHook('preHandler', agentGatewayHook({
  getPublicKey: async (keyId) => lookupKey(keyId),
  maxAgeSeconds: 480,
}));

Low-level

import { verifyAgentRequest } from 'agentbase';

const result = await verifyAgentRequest({
  authority: 'merchant.com',
  path: '/checkout',
  signatureInput: '...',
  signature: '...',
}, { getPublicKey });

License

MIT