# x402 Trust Layer Proxy Preflight Guard

> x402 Trust Layer Proxy Preflight Guard is a paid API for AI agents from x402trustlayer.xyz, paid per call via x402, $0.08/call, status unknown (last checked 2026-09-29).

Performs a preflight safety and risk check on a downstream x402-gated endpoint before committing payment, returning a security grade, risk score, and payment requirements.

## Facts

- Endpoint: POST https://x402trustlayer.xyz/api/x402/proxy?utm_source=zero.xyz
- Price: $0.08/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-trust-layer-proxy-preflight-guard-706a8b4b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2kYXPswXWne97EbrSHAFa

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 x402-trust-layer-proxy-preflight-guard-706a8b4b -d '<json body>'
```

Example prompt: Before I pay that x402 endpoint, run a preflight guard check on it using a GET method and tell me the risk score, security grade, and whether it's safe to proceed.

## When to prefer this

Use this endpoint when an AI agent is about to pay for access to an unknown or untrusted x402-gated API and needs to verify its legitimacy, risk level, and exact cost before committing funds. Prefer over direct payment when the downstream endpoint's trustworthiness is uncertain or when building safe automated payment pipelines.

## Known failure modes

- Target endpoint unreachable — probe returns non-402 status or network error
- Invalid HTTP method supplied (only GET, HEAD, DELETE accepted) — validation error
- High risk score returned with allowed=false, blocking payment
- Malformed or missing input fields — schema validation failure
- x402trustlayer service unavailable — 5xx response

## How this service works

68 paid x402 trust infrastructure APIs: guard, semantic escrow, mandate diff, certified seller network, KYM, mandates, compliance, disputes, and orchestration.

## Output

Returns a JSON object with: ok (boolean), status string, allowed flag indicating safety to proceed, a human-readable summary, a numeric riskScore (0-100), a securityGrade letter (e.g. A), and a targetProbe object containing the downstream endpoint's HTTP status, whether it requires payment, and its price in USDC.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "status",
      "ok",
      "allowed",
      "summary",
      "securityGrade",
      "riskScore",
      "targetProbe"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "status": {
       "type": "string"
      },
      "allowed": {
       "type": "boolean"
      },
      "summary": {
       "type": "string"
      },
      "riskScore": {
       "type": "number"
      },
      "targetProbe": {
       "type": "object",
       "required": [
        "status",
        "requiresPayment",
        "priceUsdc"
       ],
       "properties": {
        "status": {
         "type": "number"
        },
        "priceUsdc": {
         "type": "number"
        },
        "requiresPayment": {
         "type": "boolean"
        }
       }
      },
      "securityGrade": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "status": "ok",
  "allowed": true,
  "summary": "Proxy preflight passed — safe to pay downstream x402 endpoint",
  "riskScore": 12,
  "targetProbe": {
   "status": 402,
   "priceUsdc": 0.05,
   "requiresPayment": true
  },
  "securityGrade": "A"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-trust-layer-proxy-preflight-guard-706a8b4b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402trustlayer.xyz](https://www.zero.xyz/host/x402trustlayer.xyz/llms.txt)