# Liquid Logic Audit — USDC Payment Proof on Arc

> Liquid Logic Audit — USDC Payment Proof on Arc is a paid API for AI agents from audit.liquidlogicx.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Given a Base USDC transaction hash, records a tamper-proof settlement receipt on the Arc blockchain and returns a public verify link.

## Facts

- Endpoint: GET https://audit.liquidlogicx.com/api/prove?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/liquid-logic-audit-usdc-payment-proof-on-arc-1d2b4c14
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Rm8kiULvIemoe3kLofnaZ

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 liquid-logic-audit-usdc-payment-proof-on-arc-1d2b4c14
```

Example prompt: I just sent a USDC payment on Base with tx hash 0x4a3b2c1d...e7f6 — can you record a settlement proof on Arc and give me a public verify link I can share?

## When to prefer this

Choose this endpoint when you need a tamper-proof, publicly verifiable on-chain receipt for a USDC payment made on Base — especially for agentic payment flows using x402 protocols where audit trails matter. It is idempotent (safe to call twice), cheap ($0.02 USDC), and only charges when a new proof is actually written to Arc. Prefer it over off-chain logging when you need a public verify URL you can share with third parties as proof of settlement.

## Known failure modes

- 403 Forbidden — paying wallet is neither the sender nor recipient of the USDC transfer in the given tx hash
- Invalid tx hash format — must be 0x followed by 64 hex characters
- Tx hash contains no USDC Transfer event from Base USDC contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
- Payment not made — x402 $0.02 USDC charge failed, proof not recorded
- Network timeout fetching Base mainnet transaction data
- Transaction not yet confirmed on Base mainnet

## How this service works

Payment receipt and settlement proof for x402 and agent payments, by Liquid Logic X. Input: a Base USDC tx hash (optional memo). Output: JSON proof recorded onchain on Arc mainnet (proofId, from/to/amount, Arc tx, refId) plus a public verify link anyone can check. $0.02 USDC on Base, charged only when a proof is returned. Your paying wallet must be the tx sender or recipient. Liquid Logic X also records proofs on Tempo mainnet. Site: https://liquidlogicx.com

## Output

Returns a JSON object containing: proof status ('recorded' for new or 'existing' for already-seen), a refId (keccak256-derived settlement ID on Arc), source transfer details (from/to addresses, USDC amount, Base block timestamp, Base tx hash), Arc anchoring details (chain eip155:5042, contract address, Arc tx hash), optional memo, and a public verifyUrl to share as proof of payment. No Arc write and no charge if the tx was already recorded.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "txHash"
     ],
     "properties": {
      "memo": {
       "type": "string",
       "pattern": "^[\\x20-\\x7E]*$",
       "maxLength": 64,
       "description": "Optional plain-text note stored on-chain with the proof (printable ASCII, max 64 chars). Public."
      },
      "txHash": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{64}$",
       "description": "Base mainnet (eip155:8453) transaction hash of a USDC payment (must contain a Transfer from Base USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913). Your paying wallet must be its from or to."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "proofId",
      "status",
      "source",
      "arc",
      "verifyUrl",
      "recordedAt"
     ],
     "properties": {
      "arc": {
       "type": "object",
       "required": [
        "chain",
        "contract",
        "txHash"
       ],
       "properties": {
        "chain": {
         "type": "string",
         "const": "eip155:5042"
        },
        "txHash": {
         "type": [
          "string",
          "null"
         ],
         "pattern": "^0x[0-9a-fA-F]{64}$",
         "description": "Arc tx that recorded the proof"
        },
        "contract": {
         "type": "string",
         "const": "0x1de52cbc4490a7873ef007e51cb91a5b374facb1"
        }
       }
      },
      "memo": {
       "type": "string"
      },
      "refId": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{64}$",
       "description": "Settlement ID on Arc = keccak256(srcTxHash, payee, amountUSDC)"
      },
      "source": {
       "type": "object",
       "required": [
        "chain",
        "txHash",
        "from",
        "to",
        "amountUsdc",
        "timestamp"
       ],
       "properties": {
        "to": {
         "type": "string",
         "pattern": "^0x[0-9a-fA-F]{40}$"
        },
 
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/liquid-logic-audit-usdc-payment-proof-on-arc-1d2b4c14/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from audit.liquidlogicx.com](https://www.zero.xyz/host/audit.liquidlogicx.com/llms.txt)