verify-before-pay

Before your AI agent releases funds over x402, check the counterparty against AgentRank's settlement-grounded verdict. Drop it into any x402 client's paymentRequirementsSelector so verification runs after the payee is known but before the payment is signed.

The payer-side complement to require-rank (which is the provider side: a service gating its caller).

Why settlement-grounded

A counterfeit agent can fake fluency, a badge, even an on-chain-looking reference. It cannot fake having actually been paid. The verdict here is recomputed from real settled USDC, weighted by payer standing. In a sealed, preregistered experiment, a fake-verifiable counterfeit beat an honest agent 99% of the time without verification; performing the check flipped it, and it held 94% even against an actively lying counterparty. Surface heuristics collapse under mimicry; only verification recovers the truth.

Install & use

import { wrapFetchWithPayment } from "x402-fetch";
import { verifyingSelector } from "verify-before-pay";

// default-on: every payment verifies its counterparty first
const fetchWithPay = wrapFetchWithPayment(
  fetch, wallet, maxValue,
  verifyingSelector({ minScore: 1, onFail: "warn" })   // surface by default; flip to "block" to refuse
);

Or check directly:

import { verifyCounterparty } from "verify-before-pay";
const v = await verifyCounterparty("0xPAYEE..."); // { verified, score, usd, payers, verdict }

Policy (all optional)

| option | default | meaning | |---|---|---| | minScore | 0 | require at least this AgentRank score (0–1000) to pass | | requireVerified | false | require settlement-verified, not just scored | | onFail | "warn" | "warn" (surface + proceed) · "block" (throw) · "allow" (silent) | | failClosed | false | on a lookup error, refuse instead of failing open | | onCheck(results) | — | callback with every verdict, for logging/telemetry | | apiBase | https://api.agentrank.info | verdict source |

Defaults are non-breaking: it always checks and surfaces, never blocks, so installing it can't break a flow. Turn on minScore / requireVerified / onFail:"block" to make it a hard gate. On a verification outage it fails open by default (a verifier outage must not halt your agent).

MIT · by Crest Deployment Systems · https://agentrank.info

Example: classify before paying

See example.mjs — a drop-in payIfTrusted() that classifies the payTo (service / buyer / rail / treasury / dust) and refuses anything that is not a real service, using the free /full counterparty endpoint.

node example.mjs blockrun.ai   # service -> would pay
node example.mjs 0x1111...      # dust    -> would refuse