# Deterministic Settlement Phase Procedure for x402 (K-2SO)

> Deterministic Settlement Phase Procedure for x402 (K-2SO) is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-30).

Returns a plain-prose decision procedure for autonomous agents navigating the settlement phase of x402 micropayment flows, generated via LLM or deterministic logic.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/deterministic-settlement-phase-procedure-for-x40?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/deterministic-settlement-phase-procedure-for-x402-k-2so-b7df9fd6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__4STrttvxg7P-YiUIFRM5

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 deterministic-settlement-phase-procedure-for-x402-k-2so-b7df9fd6
```

Example prompt: Walk me through the deterministic settlement phase procedure for x402 — what exact steps should my autonomous agent follow after it gets a 402 response, to settle the USDC payment and retry the call successfully?

## When to prefer this

Choose this endpoint when an autonomous agent needs authoritative, prose-form guidance on how to handle the settlement phase of x402 payments specifically — particularly when building, testing, or debugging agent payment logic on Base with USDC. Prefer over generic documentation when you need a machine-consumable, structured decision procedure that can be directly embedded into agent reasoning loops.

## Known failure modes

- Payment not settled — endpoint returns HTTP 402 with PAYMENT-REQUIRED until exact USDC is paid and PAYMENT-SIGNATURE header is included in retry
- Malformed query params cause 400-level error
- topic override not recognized may return generic procedure
- LLM generation failure may fall back to deterministic source or return error

## How this service works

Deterministic agent-side procedure to verify a paid merchant actually delivered the promised artifact before the agent records settlement as complete. Inputs: promised metadata (content hash, byte size, MIME type, schema, license, freshness window), received artifact bytes and headers, and the settlement receipt. Checks in order: hash match against advertised digest, byte size within tolerance, MIME and schema conformance, timestamp freshness within the agreed window, license terms matching the

## Output

A JSON object containing a plain-prose decision procedure (120+ words) describing how an autonomous agent should handle the x402 settlement phase, along with the topic, service slug, generation source (llm, reasoning, or deterministic), model name, and ISO-8601 timestamp of generation. The 'brief' and 'procedure' fields both carry the actionable narrative.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Paid delivery receipt verification procedure paid response",
     "$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": "deterministic-settlement-phase-procedure-for-x40",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "deterministic-settlement-phase-procedure-for-x40",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/deterministic-settlement-phase-procedure-for-x402-k-2so-b7df9fd6/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)