# Delx Commerce — X402 Challenge Shape Check

> Delx Commerce — X402 Challenge Shape Check is a paid API for AI agents from commerce.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Validates that an X402 payment challenge object has the correct structure and required fields, returning a shape-validity report with field diagnostics.

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/x402-challenge-shape-check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-commerce-x402-challenge-shape-check-db7877ff
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Hha7T1iJUK4uvO6NhgUvK

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-challenge-shape-check-db7877ff -d '<json body>'
```

Example prompt: Can you check whether this x402 challenge object has the right shape and tell me if any required fields are missing? Here's the challenge payload: {"accept":[{"scheme":"exact","network":"base","maxAmountRequired":"1000","resource":"https://example.com/api","description":"","mimeType":"","payTo":"0xABC","maxTimeoutSeconds":60,"asset":"0xUSDC","extra":null}]}.

## When to prefer this

Use this endpoint when you need a fast, cheap ($0.001 USDC), trustless, in-memory shape check on an X402 challenge object with no data retention — especially useful as a preflight step before attempting a live payment flow, or when debugging x402 integration issues. Prefer this over manual JSON schema validation when you need a verifiable, signed evidence receipt (SHA-256 of input) proving the check was performed.

## Known failure modes

- Challenge object exceeds 128 properties limit — rejected with validation error
- Malformed JSON input — returns shape_valid: false with missing_fields populated
- Missing required top-level challenge key — request body rejected
- Network or service unavailability — HTTP 5xx error
- Insufficient USDC balance for x402 payment — HTTP 402 payment required before response

## 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 challenge is shape-valid (shape_valid: true/false), the count of accept entries (accept_count), a list of any missing fields (missing_fields), an overall status ('pass' or 'fail'), and an evidence block containing the SHA-256 hash of the input, a flag confirming no data retention, and the count of external calls made (always 0).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "challenge": {
   "type": "object",
   "description": "Challenge supplied to X402 Challenge Shape Check; used only for this bounded calculation and processed in memory without retention.",
   "maxProperties": 128,
   "additionalProperties": true
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "shape_valid": true,
   "accept_count": 1,
   "missing_fields": []
  },
  "schema": "delx/util-x402-challenge-shape-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "62072ab7fce77c19843d604f1566016ce4dbe3ea291d11d208433c905228eeab",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_challenge_shape_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-x402-challenge-shape-check-db7877ff/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)