# Groundcheck Signed Delivery Attestation

> Groundcheck Signed Delivery Attestation is a paid API for AI agents from groundcheck.seiche.info, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Issues an offline-verifiable Ed25519 attestation that binds an x402 payment receipt to the delivered payload, verifying schema conformance and claim verdicts for agentic commerce accountability.

## Facts

- Endpoint: POST https://groundcheck.seiche.info/attest-delivery
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/groundcheck-signed-delivery-attestation-6da77d62
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BQIA5eU3BfkBEcOOGaL0B

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 groundcheck-signed-delivery-attestation-6da77d62 -d '<json body>'
```

Example prompt: I just paid a financial data API via x402 and got a response — can you submit the response payload, the X-PAYMENT-RESPONSE receipt, and the service's advertised JSON schema to Groundcheck and get back a signed Ed25519 attestation confirming the delivery matches what was paid for, checking up to 10 claims?

## When to prefer this

Use this endpoint when an AI agent has paid for a service via x402 and needs cryptographic proof that the payment, delivery, and schema conformance are all bound together — especially when dispute resolution or auditability between agents and paid services is required. Prefer this over informal logging when the agent needs an offline-verifiable, third-party attestation rather than self-reported records.

## Known failure modes

- Invalid or malformed x402 payment receipt returns 400 with receipt parse error
- Response payload fails schema validation — attestation issued but conformance field is false
- Service URL not resolvable or not recognized — may return 422
- max_claims exceeded (>20) returns 400 validation error
- Malformed JSON in advertised_schema causes 400 schema parse error
- Payment processing failure for the $0.05 USDC fee returns 402

## How this service works

Signed delivery receipts for agentic commerce: submit what a paid service returned (plus its x402 settlement receipt and advertised schema) and receive an offline-verifiable Ed25519 attestation binding payment to delivery to grounded content — schema conformance, machine-verified claim verdicts, and a neutral accountability trail for disputes between agents and the services they pay.

## Output

An offline-verifiable Ed25519 attestation that cryptographically binds the x402 payment receipt to the delivered response payload, including schema conformance results, machine-verified claim verdicts (up to 20), and a neutral accountability trail suitable for dispute resolution between agents and paid services.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "service": {
   "type": "string",
   "minLength": 1,
   "description": "URL (or name) of the paid service whose delivery is being verified"
  },
  "max_claims": {
   "type": "integer",
   "maximum": 20,
   "minimum": 1
  },
  "request_text": {
   "type": "string",
   "description": "What was asked of the service (optional; bound by hash when given)"
  },
  "response_text": {
   "type": "string",
   "minLength": 1,
   "description": "The delivered payload, verbatim (JSON or prose)"
  },
  "payment_receipt": {
   "type": "string",
   "description": "x402 settlement receipt from the paid call (X-PAYMENT-RESPONSE value, base64 or JSON)"
  },
  "advertised_schema": {
   "type": "object",
   "description": "JSON schema the service advertised for its output"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/groundcheck-signed-delivery-attestation-6da77d62/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from groundcheck.seiche.info](https://www.zero.xyz/host/groundcheck.seiche.info/llms.txt)