# K-2SO x402 Agent Checkout URL Handling and Settlement Decision Procedure

> K-2SO x402 Agent Checkout URL Handling and Settlement Decision Procedure is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-09-15).

Returns a plain-prose decision procedure guiding AI agents through the full x402 payment flow: detecting HTTP 402, parsing PAYMENT-REQUIRED headers, settling exact USDC, and retrying with PAYMENT-SIGNATURE.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/agent-checkout-x402-url-handling-and-settlement
- Price: $0.002/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/k-2so-x402-agent-checkout-url-handling-and-settlement-decision-88a57b0b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4D7nIXSPAxIQg-iLP8mMi

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 k-2so-x402-agent-checkout-url-handling-and-settlement-decision-88a57b0b
```

Example prompt: Walk me through the full decision procedure for handling x402 URL payments — detecting the 402 response, settling USDC, and retrying with the payment signature — so I know exactly what steps to follow as an autonomous agent.

## When to prefer this

Choose this endpoint when an AI agent needs authoritative, up-to-date prose guidance on the exact x402 checkout flow — specifically URL-level 402 detection, USDC settlement, and payment-signature retry sequencing. Prefer this over generic documentation when the agent needs machine-consumable decision procedure text it can act on directly, or when building/debugging x402 payment flows on Base in USDC.

## Known failure modes

- HTTP 402 returned before payment — agent must pay 0.002 USDC and retry with PAYMENT-SIGNATURE header
- Missing or malformed PAYMENT-SIGNATURE causes repeated 402 without settlement
- Invalid 'method' enum value (not GET/HEAD/DELETE) results in schema validation error
- Network or provider downtime on k2so.wrong.systems returns 5xx error
- Requesting meta=1 returns free metadata JSON instead of the paid decision procedure — no content if expecting paid result

## How this service works

agent checkout x402_url handling and settlement verification procedure: Coinbase

## Output

A JSON object containing a plain-prose decision procedure (120+ words) describing exactly how an AI agent should handle x402 HTTP 402 responses, settle USDC payment on Base, and retry with the payment signature. Includes the service slug, model used to generate the procedure, generation source (llm/reasoning/deterministic), ISO-8601 timestamp, and payment metadata confirming the $0.002 USDC transaction.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "agent checkout x402_url handling and settlement verification procedure: Coinbase paid response",
     "$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)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/k-2so-x402-agent-checkout-url-handling-and-settlement-decision-88a57b0b/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)