# IntentFence x402 Quote Preflight Verifier

> IntentFence x402 Quote Preflight Verifier is a paid API for AI agents from agentpass-protocol.rmalka06.chatgpt.site, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-16).

Verifies an x402 payment quote before an AI agent pays, checking the Base USDC asset, price, payee, and resource binding for safety.

## Facts

- Endpoint: POST https://agentpass-protocol.rmalka06.chatgpt.site/api/preflight/verified
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/intentfence-x402-quote-preflight-verifier-fa1ca5a0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_9dzkr4gQsJQNU6XKF2ThX

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 intentfence-x402-quote-preflight-verifier-fa1ca5a0 -d '<json body>'
```

Example prompt: Before my agent pays this x402 quote, run an IntentFence preflight check on it — verify the Base USDC asset, confirm the payee address, price, and that the resource URL is correctly bound, and tell me if it's safe to proceed.

## When to prefer this

Use this endpoint whenever an AI agent is about to execute an x402 USDC payment and you want a caller-side safety check before funds are sent. It is especially valuable in automated multi-step agent workflows where the agent cannot manually inspect quotes, or when quotes arrive from untrusted third-party services. Prefer this over blind payment execution whenever the payee, price, or resource binding has not been independently confirmed.

## Known failure modes

- Quote asset is not Base USDC — verification fails with unsafe verdict
- Payee address mismatch between quote and expected recipient
- Resource URL binding does not match the quoted endpoint
- Malformed or missing x402 quote fields cause validation error
- Network or service unavailability returns a 5xx error

## How this service works

Fail-closed, action-bound authorization for AI agents with five-minute ES256 receipts, MCP risk scanning, and x402 payment safety.

## Output

Returns a JSON object with a safety verdict (e.g. 'safe_to_proceed'), a signed JWS Compact receipt with algorithm ES256, a unique request ID, the IntentFence score, and the verification tier (e.g. 'x402-settled').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "action": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string",
     "maxLength": 120,
     "minLength": 1
    },
    "resource": {
     "type": "string",
     "maxLength": 500
    }
   }
  },
  "proofs": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 20
  },
  "subject": {
   "type": "string",
   "maxLength": 200,
   "minLength": 1,
   "description": "Agent or principal identifier."
  },
  "constraints": {
   "type": "object",
   "properties": {
    "currency": {
     "type": "string",
     "maxLength": 12
    },
    "quoted_cost": {
     "type": "number",
     "minimum": 0
    },
    "cost_ceiling": {
     "type": "number",
     "minimum": 0
    },
    "human_approval": {
     "enum": [
      "required",
      "optional",
      "not_required"
     ],
     "type": "string"
    },
    "data_retention_hours": {
     "type": "number",
     "minimum": 0
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "status": "safe_to_proceed",
  "receipt": {
   "format": "JWS Compact",
   "signed": true,
   "algorithm": "ES256"
  },
  "request_id": "7d7fbf44-3c39-4eca-89d6-b44d756c8df1",
  "intentfence": "0.5",
  "verification_tier": "x402-settled"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/intentfence-x402-quote-preflight-verifier-fa1ca5a0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentpass-protocol.rmalka06.chatgpt.site](https://www.zero.xyz/host/agentpass-protocol.rmalka06.chatgpt.site/llms.txt)