aave-integration

# Aave V3 Integration Patterns ## Core Contracts | Contract | Purpose | |----------|---------| | `Pool` | Entry point for supply, borrow, repay, withdraw, flash loans | | `PoolAddressesProvider` | Registry for Pool and related contracts | | `AToken` | Yield-bearing receipt token (rebasing balance) | | `VariableDebtToken` | Tracks variable-rate debt | | `StableDebtToken` | Tracks stable-rate debt (deprecated in most markets) | | `PriceOracle` | Asset price feed aggregator | ## Supply / Withdraw ```solidity import {IPool} from "@aave/v3-core/contracts/interfaces/IPool.sol"; IPool pool = IPool(addressesProvider.getPool()); // Supply: approve first, then supply IERC20(asset).approve(address(pool), amount); pool.supply(asset, amount, onBehalfOf, referralCode); // Withdraw: burns aTokens, returns underlying pool.withdraw(asset, amount, to); // Use type(uint256).max to withdraw entire balance ``` ## Borrow / Repay ```solidity // Borrow: must have sufficient collateral // interestRateMode: 1 = stable (deprecated), 2 = variable pool.borrow(asset, amount, 2, referralCode, onBehalfOf); // Repay: approve first IERC20(asset).approve(address(pool), amount); pool.repay(asset, amount, 2, onBehalfOf); // Use type(uint256).max to repay full debt ``` ## Flash Loans (0.05% Fee) ```solidity import {IFlashLoanSimpleReceiver} from "@aave/v3-core/contracts/flashloan/base/FlashLoanSimpleReceiver.sol"; contract MyFlashLoan is FlashLoanSimpleReceiver { constructor(IPoolAddressesProvider provider) FlashLoanSimpleReceiver(provider) {} function executeOperation( address asset, uint256 amount, uint256 premium, // 0.05% of amount address initiator, bytes calldata params ) external override returns (bool) { require(msg.sender == address(POOL), "unauthorized"); require(initiator == address(this), "untrusted initiator"); // Your logic here — you have `amount` of `asset` _doArbitrage(asset, amount, params); // Repay: amount + premium uint256 amountOwed = amount + premium; IERC20(asset).approve(address(POOL), amountOwed); return true; } function requestFlashLoan(address asset, uint256 amount) external { POOL.flashLoanSimple(address(this), asset, amount, "", 0); } } ``` ## eMode (Efficiency Mode) eMode allows higher LTV for correlated assets (e.g., stablecoins, ETH/stETH): ```solidity // Set user's eMode category (0 = disabled) pool.setUserEMode(1); // category 1 = stablecoins (typically 97% LTV) // Query eMode config DataTypes.EModeCategory memory config = pool.getEModeCategoryData(1); // config.ltv, config.liquidationThreshold, config.liquidationBonus ``` ## Health Factor Monitoring ```solidity ( uint256 totalCollateralBase, uint256 totalDebtBase, uint256 availableBorrowsBase, uint256 currentLiquidationThreshold, uint256 ltv, uint256 healthFactor ) = pool.getUserAccountData(user); // healthFactor < 1e18 means liquidatable // Monitor and trigger repay/add collateral when healthFactor < 1.1e18 ``` ## Safe Integration Pattern ```solidity contract AaveIntegration { IPool public immutable pool; IPoolAddressesProvider public immutable addressesProvider; constructor(IPoolAddressesProvider _provider) { addressesProvider = _provider; pool = IPool(_provider.getPool()); } function safeSupply(address asset, uint256 amount) external { IERC20(asset).transferFrom(msg.sender, address(this), amount); IERC20(asset).approve(address(pool), amount); pool.supply(asset, amount, address(this), 0); } function safeWithdraw(address asset, uint256 amount, address to) external { pool.withdraw(asset, amount, to); } function getHealthFactor() external view returns (uint256) { (,,,,, uint256 hf) = pool.getUserAccountData(address(this)); return hf; } } ``` ## Risk Parameters to Verify Before integrating any asset on Aave: - **LTV**: Maximum borrowing power of the collateral - **Liquidation Threshold**: Health factor trigger for liquidation - **Liquidation Bonus**: Discount liquidators receive (e.g., 5%) - **Supply Cap**: Maximum total supply allowed - **Borrow Cap**: Maximum total borrow allowed - **Reserve Factor**: % of interest that goes to protocol treasury ## Checklist - [ ] Use `PoolAddressesProvider` to resolve `Pool` address (never hardcode) - [ ] Approve exact amounts before `supply()`/`repay()` - [ ] Handle aToken rebasing — balance changes without transfers - [ ] Check `getUserAccountData()` health factor after state changes - [ ] Validate flash loan initiator is your own contract - [ ] Account for the 0.05% flash loan premium in repayment - [ ] Test against forked mainnet with real Aave deployment - [ ] Verify supply/borrow caps haven't been reached before interacting