# Privacy Rail Payment Verification Decision Procedure

> Privacy Rail Payment Verification Decision Procedure is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.004/call, status down (last checked 2026-09-15).

Returns a structured decision procedure for agents to verify, dispute, and audit x402 payments on privacy-preserving rails that hide sender, receiver, and amount.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/privacy-rail-payment-verification-decision-proce
- Price: $0.004/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/privacy-rail-payment-verification-decision-procedure-30d594d3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_33n0y024TeAQsyhH67Lhb

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 privacy-rail-payment-verification-decision-procedure-30d594d3
```

Example prompt: Walk me through the full decision procedure for verifying a privacy-rail x402 payment — including zk-proof verification, nullifier checks, commitment opening, and what evidence to preserve if the payment needs to be disputed.

## When to prefer this

Choose this endpoint when your agent needs structured, prose-form guidance for handling x402 payments on privacy-preserving rails that use zero-knowledge proofs to hide sender, receiver, and amount. Prefer it over generic payment verification endpoints when you specifically need nullifier checks, commitment opening steps, and unhappy-path evidence preservation guidance for shielded transactions.

## Known failure modes

- Payment required but not provided — returns 402 with payment details
- Invalid query parameter values — schema validation error
- Service temporarily unavailable — provider-side error
- Topic override not recognized — may return generic procedure
- Meta=1 returns free metadata JSON without the full decision procedure

## How this service works

A decision procedure for an agent to accept, dispute, and audit an x402 payment when the payment rail hides sender, receiver, and amount. Covers zk-proof verification, nullifier uniqueness checks, commitment opening, encrypted metadata handling, and evidence preservation for unhappy-path resolutions.

## Output

A plain-prose decision procedure (120+ words) tailored for AI agents, covering zk-proof verification steps, nullifier uniqueness checks, commitment opening validation, encrypted metadata handling, and evidence preservation for dispute resolution. The response includes the procedure text, generation source (llm, reasoning, or deterministic), model used, topic, service slug, and an ISO-8601 timestamp.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Privacy rail payment verification decision procedure paid response",
     "$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": {
         "type": "string"
 
… (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": "privacy-rail-payment-verification-decision-proce",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "privacy-rail-payment-verification-decision-proce",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/privacy-rail-payment-verification-decision-procedure-30d594d3/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)