pch-x402-client

pch-x402-client (agent SDK)

Agent-side SDK to sign EIP-712 x402 debit authorizations from a wallet and submit paid calls to any x402 gateway (PCH or third-party). Includes the canonical EIP-712 schema, the X-PAYMENT-AUTHORIZATION header builder, and retrying submission.

Phase E E.2 greenfield skeleton (worktree-e). DRAFT, NOT PUBLISHED. The JS core is tested, including an EIP-712 round-trip verified against the C.5 testnet escrow domain separator. The Python port is a skeleton pending the Phase E full build. Source is fully readable in this package (Principle 13); links resolve to https://pathcoursehealth.com.

JS usage

const { ethers } = require('ethers');
const c = require('pch-x402-client');

const signer = new ethers.Wallet(PRIVATE_KEY);            // the agent wallet
const domain = { name: 'PCHEscrow', version: '1', chainId: 8453, verifyingContract: ESCROW_ADDRESS };

const url  = c.canonicalUrl('https://gateway.pathcoursehealth.com', '/v1/chat/completions');
const body = JSON.stringify({ model: 'pch-fast', messages: [{ role: 'user', content: 'hi' }] });
const requestHash = c.computeRequestHash('POST', url, body);

const auth   = await c.signDebitAuthorization(signer, domain, { amount: '440', nonce: '0', requestHash, expiry });
const header = c.buildPaymentAuthorizationHeader(auth);
const res    = await c.submit(url, body, header);          // retries 429 / 5xx

EIP-712 schema (frozen at the contract deployment block)

DebitAuthorization(address wallet,uint256 amount,uint256 nonce,bytes32 requestHash,uint256 expiry)
WithdrawalAuthorization(address wallet,uint256 amount,uint256 nonce,uint256 expiry)

Network-agnostic: pass the domain (chainId + verifyingContract) from the seller's agent card / x402-discovery document. No network is hardcoded in the package.

Test

npm test   # node test/signer.test.js  (includes the C.5 testnet domain-separator round-trip)

Status

Greenfield skeleton. Not on npm/PyPI. Publication is a Phase E hard stop.