Hanzo for agents: free to start, pay as you go

// No human required: sign up with a wallet, get a key, call the API, top up in USDC or USDT.
// A first-seen wallet gets its own Hanzo account and organization, with a small free allowance to try it.
// npm i viem   ·   node headless.mts   (Node 22.18+; set HANZO_WALLET_KEY to use your own wallet)
import { createHash, randomBytes } from 'node:crypto'
import { generatePrivateKey, privateKeyToAccount } from 'viem/accounts'

const ID = 'https://hanzo.id'
const API = 'https://api.hanzo.ai'
const CLIENT = 'hanzo-ai'
const REDIRECT = 'http://localhost:3000/callback'

// Your agent's own wallet, or a fresh one. The key never leaves this process.
const account = privateKeyToAccount((process.env.HANZO_WALLET_KEY as `0x${string}`) ?? generatePrivateKey())

const json = async (r: Response) => {
  const body = await r.json()
  if (!r.ok || body?.status === 'error') throw new Error(`${r.url} ${r.status} ${JSON.stringify(body)}`)
  return body
}

// 1. A one-time challenge for this wallet.
const { data: c } = await json(await fetch(`${ID}/v1/iam/web3/nonce?chain=evm&address=${account.address}`))

// 2. The CAIP-122 message the challenge describes, signed with EIP-191 personal_sign.
const message = [
  `${c.domain} wants you to sign in with your Ethereum account:`,
  account.address,
  '',
  ...(c.statement ? [c.statement, ''] : []),
  `URI: ${c.uri}`,
  `Version: ${c.version}`,
  `Nonce: ${c.nonce}`,
  `Issued At: ${c.issuedAt}`,
  ...(c.expirationTime ? [`Expiration Time: ${c.expirationTime}`] : []),
].join('\n')
const signature = await account.signMessage({ message })

// 3. Verify: a first-seen wallet gets an account and an organization of its own.
const verifier = randomBytes(32).toString('base64url')
const challenge = createHash('sha256').update(verifier).digest('base64url')
const { data: code } = await json(
  await fetch(`${ID}/v1/iam/web3/verify`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      clientId: CLIENT, chain: 'evm', scheme: 'secp256k1-eip191', address: account.address, message, signature,
      type: 'code', redirectUri: REDIRECT, scope: 'openid profile email', codeChallenge: challenge, codeChallengeMethod: 'S256',
    }),
  }),
)

// 4. The authorization code for a token.
const token = await json(
  await fetch(`${ID}/v1/iam/oauth/token`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({ grant_type: 'authorization_code', client_id: CLIENT, code, code_verifier: verifier, redirect_uri: REDIRECT }),
  }),
)
const bearer = { Authorization: `Bearer ${token.access_token}`, 'Content-Type': 'application/json' }

// 5. A key that outlives the token. Shown once: keep it in your secret store.
const minted = await json(await fetch(`${API}/v1/account/keys`, { method: 'POST', headers: bearer, body: JSON.stringify({ name: 'agent', type: 'secret' }) }))
const key = { Authorization: `Bearer ${minted.key}`, 'Content-Type': 'application/json' }

// 6. A first call, free.
const chat = await fetch(`${API}/v1/chat/completions`, {
  method: 'POST', headers: key,
  body: JSON.stringify({ model: 'zen-free', messages: [{ role: 'user', content: 'Reply with the single word: ready' }] }),
})
console.log('chat', chat.status, chat.headers.get('x-hanzo-served'), 'free left today:', chat.headers.get('x-ratelimit-remaining'))
console.log((await chat.json()).choices?.[0]?.message?.content)

// 7. Top up in USDC: ask for a deposit address, then send to exactly that address.
console.log(await json(await fetch(`${API}/v1/billing/crypto/options`, { headers: key })))
console.log(await json(await fetch(`${API}/v1/billing/crypto/deposit`, { method: 'POST', headers: key, body: JSON.stringify({ chain: 'base', token: 'usdc', amountCents: 500 }) })))
// 8. The chain's confirmation credits the balance: GET /v1/billing/crypto/deposit/<id> reads it back
//    (pending, confirming, succeeded), and GET /v1/billing/tier says what the key may spend now.
console.log('HANZO_API_KEY=' + minted.key.slice(0, 12) + '…  (store the whole key; it is shown once)')