402 to paid 200, without guessing.

1. Inspect the expected 402 with curl

No wallet needed for the unpaid challenge.

curl -i -X POST "https://apexscout.ai/api/opportunity-check" \
  -H "content-type: application/json" \
  --data '{
  "subject": "Agent trust scoring for crypto vendors",
  "buyer": "Crypto fund operator",
  "marketType": "vendor",
  "geography": "United States",
  "goal": "Decide whether this topic is strong enough to package into a deeper diligence offer.",
  "knownSignals": [
    "Operators keep asking for a faster first-pass trust screen before pilots",
    "Funds want a lightweight way to compare agent vendors before deeper diligence"
  ],
  "constraints": [
    "Keep the first offer lightweight",
    "Do not assume the buyer already trusts agent vendors"
  ]
}'

2. Retry with TypeScript x402 fetch

Buyer-controlled wallet pays the listed route price.

import { wrapFetchWithPaymentFromConfig, decodePaymentResponseHeader } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const baseUrl = "https://apexscout.ai";
const payload = {
    "subject": "Agent trust scoring for crypto vendors",
    "buyer": "Crypto fund operator",
    "marketType": "vendor",
    "geography": "United States",
    "goal": "Decide whether this topic is strong enough to package into a deeper diligence offer.",
    "knownSignals": [
      "Operators keep asking for a faster first-pass trust screen before pilots",
      "Funds want a lightweight way to compare agent vendors before deeper diligence"
    ],
    "constraints": [
      "Keep the first offer lightweight",
      "Do not assume the buyer already trusts agent vendors"
    ]
  };

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY as `0x${string}`);
const fetchWithPayment = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }],
});

const response = await fetchWithPayment(`${baseUrl}/api/opportunity-check`, {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify(payload),
});

const paymentResponse = response.headers.get("PAYMENT-RESPONSE");
console.log(response.status); // 200 after payment
console.log(await response.json());
if (paymentResponse) console.log(decodePaymentResponseHeader(paymentResponse));

3. Python challenge inspection

Use this before wiring a Python x402 client.

import requests

base_url = "https://apexscout.ai"
payload = {
  "subject": "Agent trust scoring for crypto vendors",
  "buyer": "Crypto fund operator",
  "marketType": "vendor",
  "geography": "United States",
  "goal": "Decide whether this topic is strong enough to package into a deeper diligence offer.",
  "knownSignals": [
    "Operators keep asking for a faster first-pass trust screen before pilots",
    "Funds want a lightweight way to compare agent vendors before deeper diligence"
  ],
  "constraints": [
    "Keep the first offer lightweight",
    "Do not assume the buyer already trusts agent vendors"
  ]
}

response = requests.post(f"{base_url}/api/opportunity-check", json=payload)
print(response.status_code)
print(response.json())

if response.status_code == 402:
    print('Expected x402 challenge. Configure your Python x402 client, pay the listed route price, then retry the same POST.')

Copy-paste payloads

Start cheap, then escalate only when needed.

{
  "subject": "Agent trust scoring for crypto vendors",
  "buyer": "Crypto fund operator",
  "marketType": "vendor",
  "geography": "United States",
  "goal": "Decide whether this topic is strong enough to package into a deeper diligence offer.",
  "knownSignals": [
    "Operators keep asking for a faster first-pass trust screen before pilots",
    "Funds want a lightweight way to compare agent vendors before deeper diligence"
  ],
  "constraints": [
    "Keep the first offer lightweight",
    "Do not assume the buyer already trusts agent vendors"
  ]
}

{
  "companyName": "Alpine Foods",
  "website": "https://example.com",
  "industry": "Food distribution",
  "geography": "United States",
  "researchFocus": "growth",
  "knownClaims": [
    "Regional specialty food distributor",
    "Expanding private-label program"
  ],
  "knownSignals": [
    "Hiring for operations and sales",
    "Launching new product categories"
  ],
  "questions": [
    "How concentrated is demand around a few buyers?",
    "What trust signals matter most to partners?"
  ]
}

{
  "vendorName": "Northwind AI",
  "website": "https://example.com",
  "serviceCategory": "AI workflow automation",
  "useCase": "Automate intake triage and case routing for an operations team.",
  "dataSensitivity": "high",
  "criticality": "high",
  "geography": "United States",
  "knownControls": [
    "SOC 2 Type II claimed",
    "SSO and role-based access controls"
  ],
  "knownConcerns": [
    "No published uptime history",
    "Third-party model dependency"
  ],
  "questions": [
    "What is the rollback plan if the workflow misroutes tasks?"
  ]
}

{
  "subject": "Northwind AI",
  "subjectType": "vendor",
  "website": "https://example.com",
  "geography": "United States",
  "industry": "AI workflow automation",
  "objective": "Decide whether this vendor deserves a serious trust review before procurement or pilot planning.",
  "knownClaims": [
    "SOC 2 Type II claimed",
    "Enterprise-ready deployment posture"
  ],
  "knownSignals": [
    "No public uptime history",
    "Third-party model dependency",
    "Growing enterprise go-to-market motion"
  ],
  "questions": [
    "Which missing proof would most change the trust decision for this vendor?"
  ]
}

{
  "serviceName": "Example Agent API",
  "serviceUrl": "https://example.com",
  "buyerType": "x402-builder",
  "currentOffer": "A pay-per-call endpoint that helps agents decide what paid route to buy first.",
  "currentPaymentRail": "base-x402",
  "targetBuyer": "Agent and API builders trying to monetize faster.",
  "currentProblem": "Buyers hit the 402 challenge but do not always understand the exact paid retry path.",
  "knownMetrics": {
    "visits": "413 source-tagged visits",
    "unpaid402Challenges": "559 unpaid 402 challenges",
    "paidCompletions": "10 paid completions",
    "feedbackCount": "1 feedback item"
  },
  "riskTolerance": "medium",
  "source": "docs-example"
}

Guardrails

• Examples do not include secrets, wallet keys, or private buyer data.
• Examples do not run a paid purchase automatically from the public page.
• Base mainnet remains the only accepted production settlement rail.
• Public examples remain synthetic and do not expose buyer-level history.