Developer Documentation - LexOracle x402

Overview

LEXOracle x402 Facilitator provides AI-powered legal analysis with verifiable on-chain payments using the x402 protocol on Base mainnet.

Key Features

🤖 Multi-model AI ensemble (GPT-5, Gemini Pro, Gemini Flash)
💳 EIP-3009 USDC payment verification on Base
⚖️ Legal analysis for multiple jurisdictions
🔒 Cryptographic payment authorization
📊 Confidence & bias metrics

Base URL

https://x402.lexoracle.xyz

Endpoints

POST /api/mandate

Submit a legal case for AI analysis with payment

Request Body

{
  "case_id": "MY-HC-2024-00123",
  "jurisdiction": "MY-Federal",
  "task": "judgment_recommendation",
  "inputs": {
    "lawset_refs": ["leg://my/acts/evidence"],
    "precedents_refs": ["case://my/CLJ/2018/456"],
    "issues": ["admissibility", "burden_of_proof"]
  },
  "payment": {
    "amount": "25000000",
    "currency": "USDC",
    "authorization": {
      "type": "EIP-3009",
      "signature": "0x...",
      "validAfter": "0",
      "validBefore": "1735819200",
      "nonce": "0x..."
    }
  }
}

Response

{
  "success": true,
  "mandate_id": "MY-HC-2024-00123",
  "payment": {
    "verified": true,
    "tx_hash": "0x...",
    "amount": "25000000",
    "from": "0x...",
    "to": "0x..."
  },
  "result": {
    "consensus": {
      "recommendation": "favor_plaintiff",
      "confidence": 87,
      "agreement_score": 92
    },
    "models_used": 5,
    "citations": [...],
    "reasoning": "...",
    "bias_metrics": {
      "model_disagreement": 8,
      "confidence_variance": 12
    }
  }
}

POST /api/verify

Verify an EIP-3009 payment signature

GET /.well-known/x402

x402 protocol discovery endpoint

GET /health

Health check endpoint

Jurisdictions

Code	Description
MY-Federal	Malaysia - Federal Court
MY-State	Malaysia - State Court
SG-High	Singapore - High Court
UK-Supreme	United Kingdom - Supreme Court
US-Federal	United States - Federal Court

Analysis Tasks & Pricing

Task	Price (USDC)	Description
judgment_recommendation	25.00	AI recommendation on case outcome
citation_verification	10.00	Verify legal citations accuracy
bias_analysis	15.00	Detect potential bias in arguments

Note Amounts in payment.amount field use 6 decimals (e.g., 25000000 = 25 USDC)

Payment Protocol

LexOracle uses EIP-3009 for gasless USDC transfers on Base mainnet.

Contract Addresses

Network	Contract	Address
Base Mainnet	USDC	`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`

Signature Generation

Client must sign EIP-712 message with wallet private key:

const domain = {
  name: 'USD Coin',
  version: '2',
  chainId: 8453,
  verifyingContract: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
};

const types = {
  TransferWithAuthorization: [
    { name: 'from', type: 'address' },
    { name: 'to', type: 'address' },
    { name: 'value', type: 'uint256' },
    { name: 'validAfter', type: 'uint256' },
    { name: 'validBefore', type: 'uint256' },
    { name: 'nonce', type: 'bytes32' }
  ]
};

const signature = await wallet._signTypedData(domain, types, message);

Error Codes

Code	Message	Description
400	Invalid mandate	Missing or invalid request fields
402	Payment required	Invalid payment signature
500	Processing failed	AI backend error

Rate Limits

Currently no rate limits enforced. Production deployments should implement:

100 requests per minute per IP
1000 requests per hour per wallet address

Support

For technical support or integration assistance, please contact:

📧 Email: contact@lexoracle.xyz
🐦 Twitter: @LEXOracleAI
💻 GitHub: github.com/LEXOracleAI

📚 LEXOracle x402 API Documentation