# Logos Chirality API – x402 Payment Challenge Auditor

> Logos Chirality API – x402 Payment Challenge Auditor is a paid API for AI agents from api.unland.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Validates and audits an x402 PAYMENT-REQUIRED challenge header against expected payment parameters, returning a detailed compatibility and safety assessment.

## Facts

- Endpoint: POST https://api.unland.dev/v1/x402/challenge-audit
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/logos-chirality-api-x402-payment-challenge-auditor-cc1ccbcd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pqOgyTv9jadaOrMYdXr8Y

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability logos-chirality-api-x402-payment-challenge-auditor-cc1ccbcd -d '<json body>'
```

Example prompt: Before I pay this x402-protected API, check the PAYMENT-REQUIRED header I received and confirm it matches: USDC contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48, recipient 0xYourAddress, amount 20000 atomic units, on the base-mainnet network — is it safe to proceed?

## When to prefer this

Use this endpoint when an AI agent or automated system receives an x402 PAYMENT-REQUIRED response and needs to verify it is safe and expected before authorizing a blockchain payment. It is particularly valuable in agentic pipelines where unattended payment authorization requires cryptographic and parameter-level assurance. Prefer this over manual inspection when you need structured, machine-readable audit results for logging or conditional logic.

## Known failure modes

- Invalid or malformed base64 in paymentRequired field — validation returns valid:false with relevant failed checks
- Address mismatch between expectedPayTo and offer — compatibleOfferFound:false
- Amount mismatch — safeToAttemptPayment:false with failed check details
- Unsupported network or scheme — checks fail with descriptive results
- Missing required fields in request body — likely 400 error or all checks failed
- Expired or structurally corrupt PAYMENT-REQUIRED header — checkCount may be low with all failed

## How this service works

Metered research tools and bounded agent services from Trevor Unland, with explicit public, private, and publication-gated boundaries.

## Output

A JSON object indicating whether the x402 challenge is valid, how many checks were run and how many failed, a summary of available offers, whether a compatible offer was found matching the expected parameters, and a top-level 'safeToAttemptPayment' boolean. Includes a timestamp of when the audit was generated.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "expectedAsset": {
   "type": "string",
   "description": "Expected non-zero EVM token contract address."
  },
  "expectedPayTo": {
   "type": "string",
   "description": "Optional expected non-zero EVM recipient address."
  },
  "expectedAmount": {
   "type": "string",
   "pattern": "^[0-9]+$",
   "maxLength": 78,
   "description": "Expected atomic token amount, not a decimal display price."
  },
  "expectedScheme": {
   "type": "string",
   "default": "exact",
   "maxLength": 40
  },
  "expectedNetwork": {
   "type": "string",
   "maxLength": 100,
   "minLength": 3
  },
  "paymentRequired": {
   "type": "string",
   "maxLength": 16384,
   "minLength": 8,
   "description": "Base64 or base64url PAYMENT-REQUIRED header value."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "valid": false,
  "checks": [],
  "checkCount": 1,
  "generatedAt": "2026-08-12T00:00:00.000Z",
  "offerSummary": [],
  "failedCheckCount": 1,
  "compatibleOfferFound": false,
  "safeToAttemptPayment": false
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/logos-chirality-api-x402-payment-challenge-auditor-cc1ccbcd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.unland.dev](https://www.zero.xyz/host/api.unland.dev/llms.txt)