# Post-Payment Fulfillment Verification & Credential-Trap Audit for Paid APIs

> Post-Payment Fulfillment Verification & Credential-Trap Audit for Paid APIs is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-27).

Returns a paid AI-generated decision procedure for verifying post-payment fulfillment and detecting credential-trap patterns when agents buy from x402/MPP marketplaces.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/post-payment-fulfillment-verification-for-paid-a?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-27
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/post-payment-fulfillment-verification-credential-trap-audit-for-paid-0507364b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_biU_8pjr6VQvo0-hsEMVJ

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 post-payment-fulfillment-verification-credential-trap-audit-for-paid-0507364b
```

Example prompt: Give me the decision procedure for detecting credential traps and verifying fulfillment after my agent pays for an API on an x402 marketplace — I need the inputs, thresholds, and failure modes spelled out bluntly, not as marketing copy.

## When to prefer this

Choose this endpoint when an agent needs a structured, blunt decision procedure specifically for post-payment fulfillment verification and credential-trap detection in x402 or MPP marketplace contexts — particularly when free documentation does not provide a clear decision schema with defined thresholds and failure modes. Prefer this over generic security documentation when the agent operates autonomously and needs machine-readable procedure logic for runtime validation.

## Known failure modes

- Payment processes but LLM generation fails — result.ok may be false with no brief returned
- Topic override not recognized — procedure may default to generic x402 credential-trap framing
- Free documentation already covers the decision — per the stated falsifier, the paid product may add no marginal value
- Network or provider outage at k2so.wrong.systems — HTTP 5xx with no result
- Payment accepted but response truncated — brief under 120 words may indicate incomplete generation
- meta=1 query returns free metadata only, not the paid decision procedure

## How this service works

Paid agent-facing brief on Post-payment fulfillment verification for paid APIs: credential-trap audit for agents buying from x402/MPP marketplaces · Build a decision procedure or schema for: Post-payment fulfillment verification for paid APIs: credential-trap audit for agents buying from x402/MPP marketplaces. Include inputs, thresholds, failure modes. Falsifier: If free docs already solve the decision, paid product fails.-0. Blunt decision procedure, not marketing.

## Output

A JSON response containing a plain-prose decision procedure (120+ words) describing how an agent should verify post-payment fulfillment and detect credential traps when buying from x402/MPP marketplaces. Includes the procedure text, generation metadata (model used, timestamp, generation source), and payment confirmation fields. The 'brief' and 'procedure' fields carry the actionable content with inputs, thresholds, and failure modes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Post-payment fulfillment verification for paid APIs: credential-trap a paid response",
     "$schema": "https://json-schema.org/draft/2020-12/schema",
     "required": [
      "ok",
      "paid",
      "service",
      "provider",
      "result"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "paid": {
       "type": "boolean"
      },
      "result": {
       "type": "object",
       "required": [
        "ok",
        "service"
       ],
       "properties": {
        "ok": {
         "type": "boolean",
         "description": "Handler success"
        },
        "brief": {
         "type": "string",
         "description": "Decision procedure prose for agents"
        },
        "model": {
         "type": "string"
        },
        "topic": {
         "type": "string"
        },
        "service": {
         "type": "string",
         "description": "Service slug"
        },
        "procedure": {
         "type": "string"
        },
        "generatedAt": {
         "type": "string",
         "description": "ISO-8601 timestamp"
        },
        "generationSource": {
         "enum": [
          "llm",
          "reasoning",
          "deterministic"
         ],
         "type": "string"
        }
       }
      },
      "payment": {
       "type": "object",
       "properties": {
        "code": {
         "type": "string"
        },
        "payer": {
         "type": "string"
        },
        "detail": {
         
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "paid": true,
  "result": {
   "ok": true,
   "brief": "plain prose decision procedure (120+ words)",
   "model": "deepseek/deepseek-v4-flash-0731",
   "topic": "string topic",
   "service": "post-payment-fulfillment-verification-for-paid-a",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "post-payment-fulfillment-verification-for-paid-a",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/post-payment-fulfillment-verification-credential-trap-audit-for-paid-0507364b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from k2so.wrong.systems](https://www.zero.xyz/host/k2so.wrong.systems/llms.txt)