@ironbridgefoundation/gitlawb

An x402 pay-rail SDK that bounds an agent's spend below the LLM and emits a re-verifiable USDC payment receipt.

It builds the HTTP 402 Payment Required descriptor for a paid call and a matching receipt you can re-check. The payment is a single Base-mainnet USDC charge split into two legs:

• dev leg → your own wallet (you pass it in)
• fee leg → the IronBridge treasury Safe (the cost of using the rail; 450 bps by default, set feeBps: 0 for a self-hosted / no-fee rail)

Install

npm install @ironbridgefoundation/gitlawb

Usage

import { charge } from "@ironbridgefoundation/gitlawb";

// Point the payout at YOUR wallet — never an IronBridge address.
const gate = charge({
  price: "0.10",
  receiver: "0xYourWalletAddressHere0000000000000000000",
  label: "lookup",
});

// gate.status === 402
// gate.body.splits === [
//   { leg: "dev",            to: "0xYourWallet…", usdc: "0.095500" },
//   { leg: "ironbridge_fee", to: "0x5Bb0…1680",   usdc: "0.004500", fee_bps: 450 },
// ]

Verify a receipt is internally consistent (splits sum to price, dev leg pays the stated receiver):

import { verifyReceipt } from "@ironbridgefoundation/gitlawb";

const { ok, reasons } = verifyReceipt(gate);
// ok === true

Optional dependency-free Express-style gate:

import { x402Middleware } from "@ironbridgefoundation/gitlawb";

app.get(
  "/paid-route",
  x402Middleware({
    price: "0.10",
    receiver: "0xYourWallet…",
    label: "lookup",
    // verify: async (req) => await yourLaneVerifier(req), // return true once paid
  }),
  handler
);

What it does

• Computes the exact two-leg USDC split (6-decimal strings) the same way the live GITLAWB lane does: dev = price * (1 - feeBps/10000), fee = price * feeBps/10000.
• Builds the 402 descriptor your server returns to require payment.
• Verifies receipt structure and arithmetic so you can re-check that the math is honest.

What it does NOT do

• It holds no private keys and custodies no funds.

• It makes no network calls inside charge() — it only builds the descriptor and verifies receipt math.

• verifyReceipt() checks structure/arithmetic only. It does not and cannot confirm on-chain settlement. To prove a payment actually cleared, re-POST to the live lane with the on-chain tx hash and let the lane verifier read the Base receipt:

  POST https://ironbridge.foundation/api/pay/gitlawb/<your-wallet>/<label>
  X-IB-Payment-Tx: <base-tx-hash>

Constants (exported)

• USDC_ADDRESS — Base USDC 0x8335…2913
• IRONBRIDGE_FEE_RECEIVER — IronBridge treasury Safe 0x5Bb0…1680
• CHAIN_ID — 8453 (Base mainnet)
• DEFAULT_FEE_BPS — 450

License

MIT © 2026 IronBridge — https://ironbridge.foundation