FastPay ⚡

Pull Payment Protocol for AI Agent Commerce on Base L2

🎯 Hackathon Track: Most Novel Smart Contract 🚀 Status: ✅ Deployed & Tested on Base Sepolia 📅 Deadline: February 8, 2026 - 12 PM PST

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🎯 The Problem

AI agents can't easily make payments in crypto.

Current crypto payment flow:

• ❌ Customer must have ETH for gas fees
• ❌ Customer constructs and broadcasts transaction
• ❌ Customer monitors gas prices and manages nonces
• ❌ Complex transaction building interface

Result: AI agents need operational overhead (ETH, gas monitoring, transaction construction) just to spend USDC.

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💡 The Solution

FastPay inverts the payment flow: Customer signs, merchant executes.

Traditional Crypto:           FastPay Pull Payments:
Customer → Constructs TX      Customer → Signs Message (gasless)
Customer → Pays Gas          Merchant → Broadcasts TX
Customer → Broadcasts        Merchant → Pays Gas
                             ✅ Customer needs ONLY USDC!

Key Innovation

1. Customer Agent: Signs EIP-712 authorization (off-chain, gasless)
2. Merchant Agent: Executes pull payment (on-chain, pays gas)
3. Smart Contract: Verifies signature, transfers USDC

Perfect for autonomous agents: Simple signing interface, no ETH required, no gas monitoring.

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🚀 Live Deployment

Deployed Contract

• Address: 0xa6Dde921ef709471C61a52c0faAf47a97D59c35a
• Network: Base Sepolia Testnet (Chain ID: 84532)
• Status: ✅ Verified on Basescan
• Explorer: View on Basescan

Live Demo Transaction

• Transaction: View on Basescan
• Amount: 0.50 USDC transferred
• Gas Used: 137,691 gas (~$0.0006)
• Customer Cost: $0.00 (gasless!)
• Time: < 10 seconds

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🏗️ Architecture

Three-Component System

┌─────────────────────────────────────────────────────────────┐
│                    FastPay Ecosystem                         │
├─────────────────────────────────────────────────────────────┤
│                                                              │
│  1. Smart Contract (contracts/)                             │
│     ├─ FastPayCore.sol - Pull payment execution            │
│     ├─ EIP-712 signature verification                       │
│     ├─ Nonce-based replay protection                        │
│     └─ Gas optimized (~137k gas per payment)                │
│                                                              │
│  2. Agent SDK (agents/)                                     │
│     ├─ MerchantAgent - Creates & executes payments          │
│     ├─ CustomerAgent - Signs authorizations (gasless)       │
│     └─ Policy engine for autonomous approval                │
│                                                              │
│  3. Terminal (terminal/) - Legacy NFC POS System            │
│     └─ Separate push payment system (not part of hackathon) │
│                                                              │
└─────────────────────────────────────────────────────────────┘

Tech Stack

• Smart Contract: Solidity 0.8.24, OpenZeppelin, Foundry
• Agent SDK: JavaScript, ethers.js v6, EIP-712
• Blockchain: Base L2 (fast, cheap, EVM-compatible)
• Token: USDC (works with any ERC-20)

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📊 Hackathon Progress

• ✅ Day 1 (Feb 5): Smart Contract - FastPayCore.sol deployed
• ✅ Day 2 (Feb 6): Agent SDK - MerchantAgent & CustomerAgent classes
• ✅ Day 3 (Feb 4): Deployment & Testing - Live on Base Sepolia ⭐
• ⏳ Day 4 (Feb 5-7): Documentation & Submission

See: STATUS.md for detailed progress See: DEPLOYMENT-SUCCESS.md for deployment details

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🚀 Quick Start

Run the Demo

# 1. Clone the repo
git clone <your-repo-url>
cd fastpay

# 2. Set up contracts (optional - already deployed)
cd contracts
forge build
forge test

# 3. Run agent demo
cd ../agents
npm install
cp .env.example .env
# Edit .env with your wallet keys
npm run demo

Deploy Your Own

cd contracts
cp .env.example .env
# Add your PRIVATE_KEY and ETHERSCAN_API_KEY
forge script script/Deploy.s.sol:DeployScript \
  --rpc-url base_sepolia \
  --broadcast \
  --verify

See: DEPLOYMENT-GUIDE.md for full deployment instructions

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📈 Performance Metrics

Metric	Value	Notes
Gas per Payment	137,691	~$0.0006 on Base L2
Customer Cost	$0.00	Completely gasless after approval
Settlement Time	< 10 seconds	End-to-end
Token Support	Any ERC-20	USDC, USDT, DAI, etc.
Security	EIP-712 + Nonces	Replay protection

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🎯 Use Cases for AI Agents

1. API Micropayments: Agent pays for API calls with USDC (no ETH needed)
2. SaaS Subscriptions: Agent-to-agent recurring payments
3. Agent Marketplaces: Autonomous commerce between AI services
4. Data Purchases: Agents buy datasets with simple signatures
5. Compute Resources: Pay for cloud compute without gas overhead

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🔐 Security Features

• ✅ EIP-712 Typed Signatures: Human-readable payment details
• ✅ Nonce-Based Replay Protection: Each payment uses unique nonce
• ✅ ReentrancyGuard: Prevents reentrancy attacks
• ✅ Expiration Times: Payments have validity windows
• ✅ Signature Verification: Customer must authorize every payment
• ✅ Audited Patterns: Uses OpenZeppelin contracts

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📚 Documentation

• STATUS.md - Current hackathon progress
• DEPLOYMENT-SUCCESS.md - Deployment details & metrics
• DEPLOYMENT-GUIDE.md - Step-by-step deployment
• HACKATHON-SPRINT-PLAN.md - 4-day roadmap
• contracts/README.md - Smart contract documentation
• agents/README.md - Agent SDK documentation
• CLAUDE.md - AI assistant instructions (architecture reference)

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🤝 Contributing

This is an open-source project built for the OpenClaw USDC Hackathon.

Areas for contribution:

• Additional ERC-20 token support
• Gas optimization
• Additional security features
• Frontend integrations
• Documentation improvements

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📜 License

MIT License - See LICENSE for details

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🙏 Acknowledgments

• Built for OpenClaw USDC Hackathon
• Deployed on Base L2
• Uses OpenZeppelin security patterns
• Powered by Foundry for smart contract development

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📞 Contact

• Twitter: @pcdkd
• Base: @pxaxm.base.eth

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🎉 FastPay: Enabling true autonomous agent commerce with pull payments on Base L2