Nexus-402

Inspiration

💡 Inspiration

As AI agents make millions of HTTP 402 micro-payments to access APIs, incoming funds sit completely idle in developer wallets earning zero return. Nexus-402 was built to solve this capital inefficiency by seamlessly connecting agentic micro-payments directly to auto-compounding DeFi vaults on Base.

⚙️ What it does

Nexus-402 combines a developer-friendly Python SDK with automated smart contract vaults:

1. HTTP 402 Interceptor: When an AI agent queries an API, our Python middleware catches the request and issues a 402 Payment Required challenge.
2. Gasless Off-Chain Signing: The AI agent signs an off-chain EIP-712 payment authorization with zero ETH gas fees.
3. On-Chain Settlement: Our relayer verifies the signature, settles the $0.01 transaction on Base Sepolia, and delivers the API response.
4. Auto-Compounding Yield: The incoming payment is immediately deposited into our YieldVault.sol contract, earning continuous APY on autopilot.

🛠️ How we built it

• Backend: FastAPI, Python SDK Middleware, Web3.py relayer.
• Frontend: Next.js (App Router), Tailwind CSS, Lucide icons, ethers.js for wallet interaction.
• Smart Contracts: Solidity contracts (MockUSDC, YieldVault) deployed and verified on Base Sepolia.

🌐 Path to Mainnet

While this MVP uses Base Sepolia testnet contracts, our mainnet architecture is designed for live DeFi integration:

• Live DeFi Protocols: Direct integration with Aave V3 and Compound V3 liquidity pools on Base.
• Gas Sponsorship: Coinbase Developer Platform (CDP) Paymaster integration for true gasless agent micro-transactions.

🏆 What's Next for Nexus-402

• Multi-token vault support (USDC, EURC, ETH).
• Dynamic yield routing to automatically chase the highest APY across Base lending markets.

Built With

• aave
• base
• cdp
• next.js
• python
• solidity