Vault Sentinel

Problem Statement

Vault Sentinel is a BTC-backed DeFi vault focused on safety, UX and composable on-chain data. Users deposit Babylon’s BTC vault token (or an equivalent wrapped BTC asset) as collateral and borrow a soft-pegged SentinelUSD stablecoin against it, with transparent health factors, clear LTV limits and battle-tested liquidation rules. The app surfaces risk in a familiar Aave-style interface, showing collateral, debt and health factor, plus an optional Octav-powered analytics tab for portfolio-level metrics and flows. Everything is built for hackathon-speed iteration but with production-style controls: per-user rate limiting, guardian pause, strict collateral thresholds and invariant tests to minimise blow-ups.

Solution

Vault Sentinel is built around a single Solidity vault contract that holds a Babylon BTC-like ERC20 as collateral, mints and burns a custom SentinelUSD ERC20 and enforces LTV, health factor and liquidation bonuses using an on-chain BTC/USD price feed. Contracts are written in Solidity 0.8.20 with Foundry for tests, fuzzing and invariants, plus Scribble annotations for runtime safety checks. The frontend is a mobile-first PWA built with Next.js 14 App Router, React and TypeScript, talking to the vault via ethers v6 and a lightweight wallet hook that supports MetaMask/Rabby, Coinbase Wallet, Phantom EVM and WalletConnect. We added a risk dashboard page that consumes a simple Next.js API route to plug in Octav-style analytics, so judges can see both protocol-level health and simulated portfolio metrics in one place.