@chainpe/sdk

x402 USDC payments + on-chain ERC-8004 reputation for the Avalanche agent economy — in 3 lines.

Give any app or AI agent the ability to discover, pay for, and rate HTTP APIs per request in USDC, settled on Avalanche C-Chain. The provider's facilitator pays the gas, so your wallet only needs USDC.

npm install @chainpe/sdk

Quickstart (the 3 lines)

import { ChainPe } from '@chainpe/sdk'

const cp = new ChainPe({ privateKey: process.env.PRIVATE_KEY!, network: 'avalanche' })
const res = await cp.fetch('https://api.example.com/paid') // auto-pays a 402
const data = await res.json()

cp.fetch is a drop-in fetch: it makes the request, and if the server answers 402 Payment Required, it signs a USDC payment (EIP-3009), retries with the X-PAYMENT header, and returns the final Response.

Discover + pay an agent (ranked by reputation)

const cp = new ChainPe({ privateKey, network: 'avalanche' })

// Ranked: scored services first, highest ⭐ first.
const services = await cp.discover('summarize')

const best = services[0]
const result = await cp.pay(best.endpoint, {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify({ text: '…' }),
  autoFeedback: true // leave on-chain ERC-8004 feedback after paying
})

console.log(result.data)        // parsed response body
console.log(result.payment)     // { amount, recipient, network, txHash }
console.log(result.reputation)  // { agentId, score, txHash } when autoFeedback

API

new ChainPe(options)

| option | default | purpose | |---|---|---| | privateKey | — (required) | EOA key that signs payments + feedback | | network | 'avalanche' | 'avalanche' or 'fuji' | | registryAddress | deployed default (mainnet) | ChainPeRegistry address | | reputationRegistry | deployed default (mainnet) | ERC-8004 Reputation Registry | | maxPerCall | '1' | max USDC to auto-pay for one 402 | | autoFeedback | false | post positive feedback after a paid call | | facilitatorUrl | — | reserved for facilitator-routed flows |

Methods:

• fetch(url, opts?) → Response — drop-in fetch that auto-pays a 402.
• pay(url, opts?) → PaidResult — same, but returns parsed data plus payment and (optional) reputation details.
• discover(query?) → RankedService[] — read the on-chain registry, annotate each service with its ERC-8004 reputation, ranked best-first. query is a search string or { query, tags, maxPrice }.
• getReputation(agentId) → ReputationSummary | null — aggregate score.
• giveFeedback(agentId, score, opts?) → txHash — post 0–100 feedback.
• getAddress() → string — the wallet address.
• balance() → { usdc, avax } — on-chain balances (human units).

Environment overrides

registryAddress / reputationRegistry fall back to CHAINPE_REGISTRY_ADDRESS and ERC8004_REPUTATION_REGISTRY env vars, then the built-in deployed defaults.

Live on Avalanche C-Chain

Works out of the box against the deployed mainnet contracts (see docs/DEPLOYMENTS.md): ChainPeRegistry 0x2a589f1e4e3Cd0A3ee986cec5202aF3760E3170E, ERC-8004 Reputation 0xfe7Df66e6BFbd3A76B68dDF26b9312E6c85a38543. USDC is available on major CEXes and bridges (e.g., Stargate).

Run the example:

CHAINPE_PRIVATE_KEY=0x... npx tsx examples/quickstart.ts

License

MIT