# Multi-rail x402 Payment Audit-Trail Binding Procedure for Agents

> Multi-rail x402 Payment Audit-Trail Binding Procedure for Agents is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Returns a decision procedure brief explaining how agents paying across chains or bridges must bind model run, session key, CCTP transfer domain, and merchant settlement into one verifiable evidence chain.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/multi-rail-x402-payment-audit-trail-binding-proc
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/multi-rail-x402-payment-audit-trail-binding-procedure-for-agents-c2084eb3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HHFMxxe4KtSW6o8oO-Z4e

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 multi-rail-x402-payment-audit-trail-binding-procedure-for-agents-c2084eb3
```

Example prompt: Give me the decision procedure for binding a multi-rail x402 payment audit trail — I need to know how to tie together the model run, session key, CCTP transfer domain, and merchant settlement into one verifiable evidence chain for a cross-chain agent payment.

## When to prefer this

Choose this endpoint when an agent needs authoritative, blunt procedural guidance on how to construct a verifiable audit trail that spans model execution, session key management, CCTP cross-domain transfers, and merchant settlement — specifically for the x402 multi-rail payment context. Prefer this over generic compute-proof or attestation procedures when the gap being addressed is the binding of all four components (model run + session key + CCTP domain + merchant settlement) into a single evidence chain.

## Known failure modes

- Payment not provided or invalid — returns 402 with payment required details
- Invalid method (POST/PUT not accepted) — returns method not allowed
- Topic override malformed — may return generic procedure rather than topic-specific brief
- Service temporarily unavailable — returns error with ok: false
- LLM generation failure — generationSource may fall back to deterministic with reduced detail

## How this service works

Deterministic procedure: an agent that pays across chains or via bridges must bind the model run, session key, transfer domain (CCTP v2 or bridge), and merchant settlement into one verifiable evidence chain. Inputs: model run id, session key, source and destination rail, transfer hash, settlement receipt. Outputs: bound, gap, or unverifiable verdict with the exact missing link. Prevents the failure where payment settled on one chain but the audit trail cannot prove which computation authorized

## Output

A structured paid response containing a prose decision-procedure brief (the 'brief' field) describing step-by-step how to bind model run, session key, CCTP transfer domain, and merchant settlement into a verifiable audit evidence chain; includes service slug, generation source (llm/reasoning/deterministic), ISO-8601 timestamp, and payment metadata confirming the micropayment was processed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Multi-rail x402 payment audit-trail binding procedure for agents paid response",
     "$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"
… (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": "multi-rail-x402-payment-audit-trail-binding-proc",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "multi-rail-x402-payment-audit-trail-binding-proc",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/multi-rail-x402-payment-audit-trail-binding-procedure-for-agents-c2084eb3/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)