ReQuard

Autonomous MEV-Triggered Liquidation Hook for Uniswap V4

ReQuard is a Uniswap V4 hook that uses Reactive Contracts to autonomously monitor collateralized LP positions and trigger on-chain liquidations the moment a position's health factor drops below a safe threshold — no keeper bots, no manual intervention.

Overview

ReQuard combines:

• Uniswap V4 Hooks - Customizable pool logic for LP position management
• Reactive Network - Event-driven smart contract execution layer
• Minimal Lending Protocol - Custom lending system for LP-backed collateral

Architecture

Contracts

1. ReQuardLending (src/ReQuardLending.sol)

   • Minimal custom lending protocol
   • Tracks LP positions as collateral
   • Manages borrowing and health factors
   • Handles liquidations

2. ReQuardHook (src/ReQuardHook.sol)

   • Uniswap V4 hook implementing IHooks interface
   • Tracks LP positions and their collateral values
   • Emits PositionHealthUpdated events for Reactive Network
   • Executes liquidations by unwinding LP positions

3. ReQuardDestination (src/ReQuardDestination.sol)

   • Receives callbacks from Reactive Network
   • Calls hook's liquidation function
   • Deployed on Base Sepolia

4. ReQuardReactive (src/ReQuardReactive.sol)

   • Reactive Contract deployed on Reactive Network
   • Monitors PositionHealthUpdated events from Base Sepolia
   • Emits Callback events to trigger liquidations
   • Implements correct Reactive Network patterns

Reactive Network Integration (Detailed)

Reactive Network is the automation layer that turns hook-emitted health signals into cross-chain liquidation transactions.

Origin chain signal: ReQuardHook emits health

Whenever a registered collateral LP position changes (via a Uniswap V4 pool action), ReQuardHook.afterModifyPosition(...) updates internal LP state and, if the LP is linked to a lending position, emits:

• PositionHealthUpdated(bytes32 indexed positionId, address indexed owner, uint256 collateralValue, uint256 debtValue, uint256 healthFactor)

Reactive subscription: watch PositionHealthUpdated

On Reactive Network, you create a subscription that monitors ReQuardHook on Base Sepolia for PositionHealthUpdated events. When an event is observed, Reactive Network calls your Reactive contract handler:

• ReQuardReactive.onPositionHealthUpdated(bytes32,address,uint256,uint256,uint256)

Handler decision: emit Callback only when unhealthy

ReQuardReactive compares healthFactor against minHealthFactor:

• If healthFactor >= minHealthFactor: it returns without emitting anything.
• If healthFactor < minHealthFactor: it emits:
  • Callback(destinationChainId, destinationContract, callbackGasLimit, payload)

The emitted callback payload encodes the destination call:

• abi.encodeWithSignature("liquidate(address,bytes32)", address(0), positionId)

The first address argument is reserved for Reactive Network ABI conventions (Reactive Network overwrites it at execution time).

Destination execution: validate Reactive VM, then call the hook

ReQuardDestination receives the callback via:

• liquidate(address rvmAddress, bytes32 positionId)

The destination enforces access control using:

• onlyReactiveVm (it checks msg.sender == reactiveVm)

After validation it calls:

• hook.liquidatePosition(positionId)

Setup instructions

For subscription topic hashes, required handler signature checks, and operational troubleshooting, see REACTIVE_SETUP.md.

Features

• ✅ Autonomous Liquidations - No keeper bots required
• ✅ Real-time Monitoring - Reactive Network monitors positions continuously
• ✅ Uniswap V4 Integration - Proper hook interfaces and LP management
• ✅ Health Factor Tracking - Automatic health calculation and threshold monitoring
• ✅ Fee Redistribution - Liquidation fees redistributed to LPs

Quick Start

Prerequisites

• Foundry installed
• Base Sepolia testnet access
• Reactive Network Lasna Testnet access

Build

forge build

Deploy

1. Configure environment variables used by the scripts (PRIVATE_KEY, and for Reactive deployment DESTINATION_CONTRACT, plus optional overrides for chain ids and thresholds).

2. Deploy contracts on Base Sepolia:

forge script script/Deploy.s.sol:DeployScript --rpc-url $BASE_SEPOLIA_RPC_URL --broadcast --verify

3. Deploy Reactive Contract on Reactive Network Lasna Testnet

4. Configure Reactive Network subscription (see REACTIVE_SETUP.md)

Configuration

Chain IDs:

• Base Sepolia: 84531
• Reactive Network Lasna Testnet: 5318007

Health Factor Threshold:

• Default: 1.2e18 (120%)
• Positions below this threshold are liquidated

Gas Limits:

• Callback Gas Limit: 500000

Project Structure

src/
├── interfaces/
│   └── IUniswapV4Hooks.sol    # Uniswap V4 hook interfaces
├── ReQuardLending.sol          # Minimal lending protocol
├── ReQuardHook.sol             # Uniswap V4 hook
├── ReQuardDestination.sol       # Callback receiver
└── ReQuardReactive.sol         # Reactive Contract

script/
└── Deploy.s.sol                # Deployment script

REACTIVE_SETUP.md               # Reactive Network setup guide
ReQuard-PRD.md                  # Product requirements document

How It Works

1. A pool action triggers ReQuardHook.afterModifyPosition(...) (Uniswap V4 hook callback).
2. If the LP position has been registered as collateral in ReQuardLending, the hook emits PositionHealthUpdated(...).
3. Reactive Network detects the event and calls ReQuardReactive.onPositionHealthUpdated(...).
4. ReQuardReactive checks healthFactor against minHealthFactor.
5. If unhealthy, ReQuardReactive emits Callback(...) with a payload encoding liquidate(address,bytes32) and the positionId.
6. Reactive Network executes the callback on the destination chain by calling ReQuardDestination.liquidate(...).
7. ReQuardDestination verifies the Reactive VM and forwards to ReQuardHook.liquidatePosition(positionId).
8. The hook liquidates via ReQuardLending.liquidatePosition(positionId), unwinds LP liquidity, and accumulates liquidation fees for distribution.

Testing

forge test

This repo includes:

• Unit tests for ReQuardReactive, ReQuardLending, and ReQuardHook.
• An integration test that drives the liquidation flow through ReQuardHook -> ReQuardReactive -> ReQuardDestination -> ReQuardHook -> ReQuardLending.
• Fuzz tests for callback gating, health-factor math, and liquidation branching.

Resources

• Reactive Network Docs
• Reactive Contracts Guide
• Uniswap V4 Documentation
• Demo Repository

License

UNLICENSED