Fusion+ Aptos Extension

🚀 True Gasless Cross-Chain Swaps between Ethereum and Aptos using the Fusion+ protocol.

✨ Users pay ZERO gas fees - Just sign transactions, resolver covers all gas costs!

Quick Start Testing Guide

1. Install All Dependencies

# From root directory
npm install

# Install backend dependencies
cd backend/order-engine && npm install && cd ../..
cd backend/resolver && npm install && cd ../..

# Install frontend dependencies  
cd frontend && npm install && cd ..

# Install contract dependencies
cd contracts/ethereum && npm install && cd ../..

2. Run Tests

Test Smart Contracts

# Test Ethereum contracts
cd contracts/ethereum
npx hardhat test

# Test Aptos contracts
cd contracts/aptos
aptos move test --named-addresses fusion_plus=0xCAFE

Test Order Engine

cd backend/order-engine
npm test

3. Run the System Locally

You'll need 3 terminal windows:

Terminal 1 - Order Engine Backend:

cd backend/order-engine
npm run dev
# Should see: "Order engine server running on port 3001"

Terminal 2 - Frontend:

cd frontend
npm start
# Opens http://localhost:3000

Terminal 3 - Test the API:

# Create a test order
curl -X POST http://localhost:3001/api/orders \
  -H "Content-Type: application/json" \
  -d '{
    "fromChain": "ETHEREUM",
    "toChain": "APTOS",
    "fromToken": "0x0000000000000000000000000000000000000000",
    "toToken": "0x0000000000000000000000000000000000000000",
    "fromAmount": "1000000000000000",
    "minToAmount": "100000000",
    "maker": "0x742d35Cc6634C0532925a3b844Bc9e7595f00000",
    "receiver": "0x742d35Cc6634C0532925a3b844Bc9e7595f00000",
    "deadline": 1999999999,
    "nonce": "123456",
    "partialFillAllowed": false,
    "signature": "0x00"
  }'

# Get all orders
curl http://localhost:3001/api/orders

# Get specific order (replace ORDER_ID)
curl http://localhost:3001/api/orders/ORDER_ID

4. Test with UI

1. Open http://localhost:3000
2. Connect MetaMask (Sepolia testnet)
3. Connect Petra wallet (Aptos testnet)
4. Create a swap order
5. Monitor order status in the Order History section

5. Try Gasless WETH → APT Swaps

🚀 Experience true gasless swaps:

1. Get WETH: Wrap some ETH to WETH on Sepolia
2. One-Time Setup: Approve WETH to gasless escrow (pays gas once)
3. Gasless Forever: All future swaps are gasless!
   • Select WETH → APT
   • Sign meta-transaction (no gas)
   • Receive APT automatically
4. Monitor Progress: Watch real-time swap execution with zero fees

Architecture Overview

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│                 │     │                 │     │                 │
│  Ethereum       │     │  Order Engine   │     │     Aptos       │
│  Escrow         │◄────┤  (Off-chain)    ├────►│    Escrow       │
│  Contract       │     │                 │     │    Module       │
│                 │     └────────┬────────┘     │                 │
└─────────────────┘              │              └─────────────────┘
                                 │
                        ┌────────▼────────┐
                        │                 │
                        │    Resolver     │
                        │   (Relayer)     │
                        │                 │
                        └─────────────────┘

Key Features

🌟 Gasless WETH to APT Swaps

• Zero Gas Fees: Users pay no gas after one-time WETH approval
• Meta-Transactions: EIP-712 signatures enable gasless WETH transfers
• Production Ready: Deployed and tested on Sepolia + Aptos Testnet

🔒 Atomic Security

• Hashlock/Timelock: Cryptographic guarantees for cross-chain safety
• Trustless: No custody risk, funds locked in smart contracts
• Resolver Incentives: Safety deposits ensure completion

🔄 Cross-Chain Support

• WETH → APT: Gasless swaps using meta-transactions
• APT → WETH: Sponsored transactions on Aptos
• Bidirectional: Full support for both swap directions

⚡ User Experience

• One-Click Approval: Approve WETH once, swap forever gaslessly
• Real-Time Updates: Live swap progress with asset flow tracking
• Auto-Complete: Resolver handles all on-chain execution

Contract Addresses (Testnet)

Ethereum (Sepolia)

• Regular Escrow: 0x5Ea57C2Fb5f054E9bdBdb3449135f823439E1338
• Gasless Escrow: 0x4868C055E894f6C774960a175aD11Dec26f8475f ✨
• WETH Token: 0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14

Aptos (Testnet)

• Escrow Module: 0x9835a69eb93fd4d86c975429a511ed3b2900becbcbb4258f7da57cc253ab9fca

Technical Documentation

📚 Detailed Guides:

• Gasless WETH Swaps - Complete technical implementation
• Deployment Summary - Contract deployment details
• Testing Scripts - Utilities for testing gasless functionality

🔧 Smart Contracts:

• FusionPlusGaslessEscrow.sol - Gasless escrow with meta-transactions
• Aptos Escrow Module - Cross-chain escrow on Aptos

Development Mode

The system includes development mode signatures that bypass full validation for testing. In production, proper signature validation must be implemented.

Troubleshooting

General Issues

1. CORS errors: Ensure backend is running before frontend
2. Connection issues: Check you're on correct networks (Sepolia/Aptos Testnet)
3. Order creation fails: Check browser console for detailed errors
4. WebSocket not connecting: Verify order engine is running on port 3001

Gasless Swap Issues

5. "Gasless swaps require WETH approval": Approve WETH to gasless escrow contract first
6. Meta-transaction fails: Check WETH balance and allowance using debug scripts
7. Escrow not found: Ensure Aptos escrow module is deployed correctly
8. Signature errors: Confirm MetaMask is connected and on Sepolia testnet

Debug Commands

# Check WETH approval status
node scripts/check-weth-approval-gasless.js

# Test gasless functionality  
node scripts/test-gasless-weth.js

# Decode failed transactions
node scripts/decode-gasless-tx.js