mpp

MPP Example

Demonstrates Machine Payment Protocol (MPP) integration with the Tempo Accounts SDK. The browser auto-pays HTTP 402 Payment Required challenges served by a Hono server using the mppx/hono middleware.

MPP support is enabled by default on the Tempo Accounts SDK provider — no extra client-side configuration is required.

Intents

Two intents are demonstrated, both served from a single Hono app powered by mppx/hono:

Endpoint	Intent	Cost	Notes
GET /api/auth	zero-charge	$0	Replay-protected proof of account ownership. No on-chain transaction.
GET /api/fortune	charge	$0.01 / call	One-shot pathUSD transfer, settled on-chain before the response is returned.

Setup

npx gitpick tempoxyz/accounts/examples/mpp
npm i
npm dev

Sign in with a Tempo Wallet account on testnet, then click each intent button to watch the SDK auto-pay the 402 challenge and return the protected payload.

How it works

The worker (worker/index.ts) configures an MPP handler with the tempo() payment method:

import { Hono } from 'hono'
import { Mppx, tempo } from 'mppx/hono'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount('0x...')

const mppx = Mppx.create({
  methods: [tempo({ account, currency: '0x...', feePayer: true, testnet: true })],
  realm: 'mpp',
  secretKey: '...',
})

const app = new Hono()
app.get('/api/fortune', mppx.charge({ amount: '0.01' }), (c) => c.json({ fortune: '...' }))
app.get('/api/auth',    mppx.charge({ amount: '0' }),    (c) => c.json({ ok: true }))

On the client, the standard tempoWallet() connector is enough — the Provider.create({ mpp: true }) default automatically intercepts the 402 responses, signs the payment with the connected account, and retries the original request with the credential attached.

For pull-mode charge credentials, feePayer: true lets the worker co-sign and broadcast the signed payment transaction. Without a fee payer, the worker can verify the credential shape but cannot pay the transaction fee needed to settle the charge on-chain.