Overview

Production-grade DeFi banking suite — 4 Solidity contracts, Express+Prisma indexer, Next.js frontend. Live at bankchain.vercel.app.

Key Highlights

• 4 contracts: BankToken (ERC20 + permit + pausable), SavingsVault (ERC4626 yield aggregator), LendingPool (over-collateralized, RAY borrow index, 80% LTV, on-chain liquidation), Treasury (OZ TimelockController, 24h delay)
• Hardhat + Solidity 0.8.20 + OpenZeppelin 5.x with optimizer enabled
• 48 Hardhat tests passing — mint, burn, share math, borrow, repay, 100-block interest accrual, liquidation, edge cases
• Deterministic on-chain rules monitor — emits RebalanceProposals when health factor / utilization / pause thresholds cross (no LLM, no API key)
• Express + Prisma + ethers v6 backend with WebSocket event indexer and universal revert-reason decoder
• Next.js 14 frontend with wagmi + viem + RainbowKit, deployed live on Vercel (bankchain.vercel.app)
• ChainGuard (auto-detect wrong chain), LiveStats (TVL/supply from chain), and a deterministic slash-command interface (no NLP)
• Three real protocol bugs caught and fixed by the test suite before deployment: totalBorrows underflow, borrow liquidity check, liquidate empty-position bypass

Tech Stack

Details

Four production-grade Solidity 0.8.20 contracts form the protocol: BankToken (ERC20 with EIP-2612 permit, pausable, burnable), SavingsVault (OZ ERC4626 yield-bearing wrapper with 5% performance fee), LendingPool (over-collateralized lending with Compound-style RAY borrow index, 80% LTV, on-chain liquidation), and Treasury (OZ TimelockController owning every protocol parameter with 24h delay). A deterministic on-chain rules monitor watches LendingPool state, computes utilization, sweeps user health factors, and emits structured RebalanceProposal events when thresholds are crossed — pure rules, no LLM, no API key. Three real bugs caught and fixed during development by the test suite: repay/liquidate totalBorrows underflow, borrow liquidity check, and liquidate empty-position bypass.

Architecture

┌─────────────────┐     ┌─────────────────┐
│  contracts/     │◀────│   backend/      │
│  Lending        │     │  Express+Prisma │
│  Token          │     │  + indexer      │
│  Treasury       │     └────────┬────────┘
│  Vault          │              │
└────────┬────────┘              │
         │                       │
         ▼                       ▼
┌─────────────────┐     ┌─────────────────┐
│  frontend/      │     │  ai-agent/      │
│  Next.js 14     │     │  rules monitor  │
│  + wagmi        │     │  (no LLM)       │
└─────────────────┘     └─────────────────┘