# Delx Commerce X402 Idempotency Check

> Delx Commerce X402 Idempotency Check is a paid API for AI agents from commerce.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Checks whether a payment key and delivery key match, verifying idempotency for X402 pay-per-result transactions without retaining input data.

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/x402-idempotency-check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-commerce-x402-idempotency-check-897044d8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rem0L6JEzY4LEuH8ps-W_

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 delx-commerce-x402-idempotency-check-897044d8 -d '<json body>'
```

Example prompt: Check if payment key 'job-42' and delivery key 'job-42' match for an x402 idempotency check on Delx Commerce — I want to confirm this transaction hasn't been double-processed.

## When to prefer this

Choose this endpoint when you need to cryptographically verify that a payment key and delivery key correspond for an x402 pay-per-result transaction on Delx Commerce, especially when preventing replay attacks or double-processing in an agentic payment workflow. It is the right choice when you need verifiable, in-memory-only key matching with no data retention and an auditable SHA256 evidence trail.

## Known failure modes

- Keys do not match — matched: false returned with status 'fail'
- Missing required fields (payment_key or delivery_key) may result in a validation error
- Malformed input exceeding maxLength of 8192 characters may be rejected
- Network timeout or service unavailability returns no result

## How this service works

Pay-per-result APIs for agents. No signup. Exact price. Verifiable delivery. USDC on Base + Solana via x402.

## Output

Returns a JSON object indicating whether the payment_key and delivery_key match (matched: true/false), echoes both keys, reports the operation status (pass/fail), and provides an evidence block containing a SHA256 hash of the input, confirmation that no data was retained, and the count of external calls made (always 0). The schema version and operation name are also included.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "payment_key": {
   "type": "string",
   "maxLength": 8192,
   "description": "Payment Key supplied to X402 Idempotency Check; used only for this bounded calculation and processed in memory without retention."
  },
  "delivery_key": {
   "type": "string",
   "maxLength": 8192,
   "description": "Delivery Key supplied to X402 Idempotency Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "matched": true,
   "payment_key": "job-42",
   "delivery_key": "job-42"
  },
  "schema": "delx/util-x402-idempotency-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "a9aa562b36a16cb899fdccfd5bcae9beef661bc9955a23c2dab0076b08c36ff5",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_idempotency_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-x402-idempotency-check-897044d8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from commerce.delx.ai](https://www.zero.xyz/host/commerce.delx.ai/llms.txt)