QWED UCP: transaction verification for AI commerce

AI Agent → UCP Checkout → QWED-UCP Guard → Payment Gateway
                              │
                         ✅ Pass → Continue
                         ❌ Fail → Block + Error

┌─────────────────────────────────────────────────────────────────┐
│                    AI Shopping Agent                             │
│                    (Claude, GPT, etc.)                           │
└──────────────────────────┬──────────────────────────────────────┘
                           │
                           │ UCP Checkout Request
                           ▼
┌─────────────────────────────────────────────────────────────────┐
│                    QWED-UCP Middleware                           │
├─────────────────────────────────────────────────────────────────┤
│                                                                  │
│  ┌──────────────┐  ┌──────────────┐  ┌────────────────────────┐ │
│  │ Money Guard  │  │ State Guard  │  │   Line Items Guard     │ │
│  │   ₹+$+¥     │  │  → → → →     │  │   qty × price = total  │ │
│  └──────────────┘  └──────────────┘  └────────────────────────┘ │
│                                                                  │
│  ┌──────────────┐  ┌──────────────┐  ┌────────────────────────┐ │
│  │Discount Guard│  │Currency Guard│  │    Schema Guard        │ │
│  │   10% = 10   │  │  USD/EUR/JPY │  │    JSON Validation     │ │
│  └──────────────┘  └──────────────┘  └────────────────────────┘ │
│                                                                  │
│  ┌──────────────┐  ┌──────────────┐  ┌────────────────────────┐ │
│  │ Refund Guard │  │  Tip Guard   │  │    Fee Guard           │ │
│  │  full/partial│  │  pre/post-tax│  │    service/delivery    │ │
│  └──────────────┘  └──────────────┘  └────────────────────────┘ │
│                                                                  │
│  ┌────────────────────────────────────────────────────────────┐  │
│  │                  Attestation Guard (JWT)                   │  │
│  └────────────────────────────────────────────────────────────┘  │
│                                                                  │
│                     All Guards Pass?                             │
│                    YES ─────┬───── NO                            │
│                             │                                    │
└─────────────────────────────┼────────────────────────────────────┘
                              │
              ┌───────────────┴────────────────┐
              ▼                                ▼
        ┌──────────┐                    ┌──────────────┐
        │ Payment  │                    │ 422 Error    │
        │ Gateway  │                    │ + Details    │
        └──────────┘                    └──────────────┘

pip install qwed-ucp

npm install qwed-ucp-middleware

from qwed_ucp import UCPVerifier

verifier = UCPVerifier()

# Verify a checkout
result = verifier.verify_checkout({
    "currency": "USD",
    "status": "ready_for_complete",
    "line_items": [
        {"id": "roses", "quantity": 2, "item": {"price": 35.00}},
        {"id": "vase", "quantity": 1, "item": {"price": 15.00}}
    ],
    "totals": [
        {"type": "subtotal", "amount": 85.00},  # 2×35 + 1×15 = 85 ✓
        {"type": "discount", "amount": 8.50},   # 10% off
        {"type": "tax", "amount": 6.29},        # 8.2% tax on $76.50
        {"type": "total", "amount": 82.79}      # 85 - 8.50 + 6.29 = 82.79 ✓
    ]
})

if result.verified:
    print("✅ Checkout verified! Safe to proceed to payment.")
else:
    print(f"❌ Verification failed: {result.error}")
    print(f"   Guard: {result.failed_guard}")

from fastapi import FastAPI
from qwed_ucp.middleware.fastapi import QWEDUCPMiddleware

app = FastAPI()

# Add QWED-UCP middleware - automatically verifies all /checkout endpoints
app.add_middleware(QWEDUCPMiddleware)

@app.post("/checkout")
async def checkout(request: CheckoutRequest):
    # If we get here, QWED-UCP already verified the math!
    return {"status": "completed", "order_id": "ORD-123"}

const express = require('express');
const { createQWEDUCPMiddleware } = require('qwed-ucp-middleware');

const app = express();

// Add QWED-UCP middleware
app.use('/checkout', createQWEDUCPMiddleware());

app.post('/checkout', (req, res) => {
    // If we get here, QWED-UCP already verified the math!
    res.json({ status: 'completed', orderId: 'ORD-123' });
});

name: Commerce Audit

on:
  push:
    paths:
      - 'logs/transactions/**'

jobs:
  audit:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      
      - name: Audit Commerce Transactions
        uses: QWED-AI/qwed-ucp@v0.3.0
        with:
          log_path: logs/transactions/
          strict_mode: true

🛡️ QWED-UCP Audit: 3 vulnerabilities blocked

1. ❌ Penny Slicing: tx_001.json - Tax $7.99 should be $8.00
2. ❌ Zombie Return: tx_045.json - Return without original order
3. ❌ Phantom Discount: tx_089.json - 15% discount on non-sale item

Action: BLOCKED (Exit Code 1)

from qwed_ucp import UCPVerifier, MoneyGuard

# Custom tolerance for floating-point errors
verifier = UCPVerifier(
    money_guard=MoneyGuard(tolerance=0.02),  # $0.02 tolerance
    strict_mode=False  # Allow minor schema violations
)