# A2A-to-x402 Settlement Identity Continuity Gate

> A2A-to-x402 Settlement Identity Continuity Gate is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-10-21).

Verifies that the agent identity that concluded an A2A negotiation (ERC-8004) is the same identity authorized to settle the outcome via x402 payment.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/agent-stack-interop-binding-a2a-negotiation-outc?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: down
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/a2a-to-x402-settlement-identity-continuity-gate-3bee804c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4soai5LkWfNdMX3trzmtL

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 a2a-to-x402-settlement-identity-continuity-gate-3bee804c
```

Example prompt: Before we settle this A2A negotiation outcome via x402, check whether the ERC-8004 identity that concluded the negotiation — including its issuer attestation and delegation scope — still covers the negotiated deliverable and matches the x402 payer address.

## When to prefer this

Use this endpoint at the exact seam between A2A negotiation completion and x402 payment settlement in any autonomous agent pipeline. It is specifically designed for the ERC-8004 + x402 interop pattern and performs ordered deterministic checks that would otherwise require custom logic. Prefer it over general identity validators when you need to enforce delegation scope continuity across the A2A-to-payment handoff in a single call.

## Known failure modes

- ERC-8004 identity claim missing or malformed from A2A outcome — gate returns ok:false with explanation
- Delegation scope expired or revoked since negotiation — gate blocks settlement
- x402 payer address does not match negotiating identity — identity continuity failure
- Issuer attestation invalid or unverifiable — gate returns error
- Payment not received (x402 402 response) — free metadata available via ?meta=1
- Network or upstream resolver unavailable — service error

## How this service works

Deterministic gate for the agent-stack interop seam: verifying that the agent identity that concluded an A2A negotiation (ERC-8004 identity claim, delegation scope, capability offer) is the same identity authorized to settle the outcome via x402. Ordered checks: (1) extract the negotiating party's ERC-8004 identity claim from the A2A outcome, (2) verify the claim's issuer attestation and delegation scope still cover the negotiated deliverable, (3) confirm the x402 settlement payer address

## Output

Returns a structured result with an ok boolean, a human-readable decision procedure brief for agents, the service slug, model used, ISO-8601 timestamp, and generation source (llm/reasoning/deterministic). Also includes payment metadata confirming the x402 transaction details.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "agent-stack interop: A2A-to-settlement identity continuity gate paid response",
     "$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": "agent-stack-interop-binding-a2a-negotiation-outc",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "agent-stack-interop-binding-a2a-negotiation-outc",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/a2a-to-x402-settlement-identity-continuity-gate-3bee804c/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)