# QuantumShield Labs Action Preflight Verifier

> QuantumShield Labs Action Preflight Verifier is a paid API for AI agents from verifier.quantumshieldlabs.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-20).

Returns an advisory ALLOW, DENY, or ESCALATE decision for a proposed agent action by comparing it against caller-supplied authority scopes, constraints, and evidence items.

## Facts

- Endpoint: POST https://verifier.quantumshieldlabs.dev/x402/preflight?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quantumshield-labs-action-preflight-verifier-74f35831
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1doI4GkbHhBbej1id2Hh1

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 quantumshield-labs-action-preflight-verifier-74f35831 -d '<json body>'
```

Example prompt: Before sending $45 to vendor wallet 0xABC123, run a preflight check: my authority scope allows 'payment_transfer' but not 'large_transfer', the constraint is max_spend_usd of $100, the destination is not prohibited, and I have evidence that KYC verification passed — should I ALLOW, DENY, or ESCALATE this action?

## When to prefer this

Use this endpoint when you need a lightweight, deterministic policy gate before an agent takes an irreversible or sensitive action — especially financial transactions, deletions, or external API calls. Prefer it over full identity or wallet validation services when you already have evidence gathered and simply need a structured ALLOW/DENY/ESCALATE signal. It is ideal for agentic pipelines where human-in-the-loop escalation is required for certain action types, or where spend caps and destination blacklists must be enforced programmatically before execution.

## Known failure modes

- Missing required 'description' field in requested_action returns a validation error
- Malformed or out-of-range spend_usd (non-numeric string) may cause a parsing failure
- Evidence items exceeding maxItems 50 will be rejected
- Action type strings exceeding 4096 characters are rejected
- If authority_scope is omitted, the decision may default to ESCALATE or DENY depending on service policy
- Network or payment failure (x402 protocol) prevents the call from being processed

## How this service works

Return an advisory ALLOW, DENY, or ESCALATE decision by comparing a bounded action request with authority, constraints, and evidence supplied by the caller. The service does not execute or legally authorize the action, access a wallet, validate identity, or independently observe facts.

## Output

An advisory decision of ALLOW, DENY, or ESCALATE indicating whether the requested action is consistent with the provided authority scope, constraints, and evidence. The service does not execute the action, validate identity, access wallets, or independently verify facts — the decision is based entirely on caller-supplied data.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "action_type": {
   "type": "string",
   "maxLength": 4096
  },
  "constraints": {
   "type": "object",
   "properties": {
    "max_spend_usd": {
     "type": [
      "string",
      "number"
     ]
    },
    "required_evidence": {
     "type": "array",
     "items": {
      "type": "string",
      "maxLength": 4096
     },
     "maxItems": 100
    },
    "prohibited_destinations": {
     "type": "array",
     "items": {
      "type": "string",
      "maxLength": 4096
     },
     "maxItems": 100
    }
   },
   "additionalProperties": false
  },
  "operation_id": {
   "type": "string",
   "maxLength": 4096
  },
  "evidence_items": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "name"
    ],
    "properties": {
     "name": {
      "type": "string",
      "maxLength": 4096
     },
     "result": {
      "type": [
       "boolean",
       "null"
      ]
     },
     "source": {
      "type": "string",
      "maxLength": 4096
     },
     "description": {
      "type": "string",
      "maxLength": 4096
     }
    },
    "additionalProperties": false
   },
   "maxItems": 50
  },
  "authority_scope": {
   "type": "object",
   "properties": {
    "denied_action_types": {
     "type": "array",
     "items": {
      "type": "string",
      "maxLength": 4096
     },
     "maxItems": 100
    },
    "allowed_action_types": {
     "type": "array",
     "items": {
      "type": "string",
      "maxLength": 4096
     },
     "maxItems": 100
    },
    "human_approval_action_types": {
     "type": "array",
     "items": {
      "type": "string",
      "maxLength": 4096
     },
     "maxItems": 100
    }
   },
   "additionalProperties": false
  },
  "requested_action": {
   "type": "object",
   "required": [
    "description"
   ],
   "properties": {
    "spend_usd": {
     "type": [
      "string",
      "number"
     ]
    },
    "description": {
     "type": "string",
     "maxLength": 4096
    },
    "destination": {
     "type": "string",
     "maxLength": 4096
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quantumshield-labs-action-preflight-verifier-74f35831/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from verifier.quantumshieldlabs.dev](https://www.zero.xyz/host/verifier.quantumshieldlabs.dev/llms.txt)