# YearnAaveV3USDTLenderStrategy ## Overview The YearnAaveV3USDTLenderStrategy contract is a strategy that supplies USDT into a Yearn V3 Vault for AAVE v3 lending. It manages conversions between USDCe and USDT through Curve's AtriCrypto zapper and includes safety margins for liquidations. ## Constants ```solidity ICurveAtriCryptoZapper constant zapper = ICurveAtriCryptoZapper(CURVE_AAVE_ATRICRYPTO_ZAPPER_POLYGON); // Curve zapper address public constant usdt = USDT_POLYGON; // USDT address ``` ## Functions ### Initialization Functions #### initialize ```solidity function initialize( IMaxApyVault _vault, address[] calldata _keepers, bytes32 _strategyName, address _strategist, IYVaultV3 _yVault ) public virtual override initializer ``` Initializes the strategy and sets up trading limits. Parameters: * `_vault`: MaxApy vault address * `_keepers`: Array of keeper addresses * `_strategyName`: Name of the strategy * `_strategist`: Strategist address * `_yVault`: Yearn V3 vault address ### Core Functions #### liquidateExact ```solidity function liquidateExact(uint256 amountNeeded) external override checkRoles(VAULT_ROLE) returns (uint256 loss) ``` Withdraws exact amount to vault with loss calculation. Parameters: * `amountNeeded`: Amount to withdraw Returns: * `loss`: Amount of realized loss ### View Functions #### previewLiquidate ```solidity function previewLiquidate(uint256 requestedAmount) public view override returns (uint256 liquidatedAmount) ``` Simulates withdrawal including losses and conversion rates. Parameters: * `requestedAmount`: Amount to withdraw Returns: * `liquidatedAmount`: Expected output amount #### previewLiquidateExact ```solidity function previewLiquidateExact(uint256 liquidatedAmount) public view override returns (uint256 requestedAmount) ``` Calculates input needed with 1% safety margin. Parameters: * `liquidatedAmount`: Desired output amount Returns: * `requestedAmount`: Required input amount #### maxLiquidate ```solidity function maxLiquidate() public view override returns (uint256) ``` Returns maximum withdrawable amount after losses. Returns: * Maximum withdrawable amount #### maxLiquidateExact ```solidity function maxLiquidateExact() public view override returns (uint256) ``` Returns maximum withdrawable amount with safety margin. Returns: * Maximum withdrawable amount before losses ### Internal Core Functions #### \_invest ```solidity function _invest(uint256 amount, uint256 minOutputAfterInvestment) internal override returns (uint256 depositedAmount) ``` Invests assets by: 1. Converting USDCe to USDT through zapper 2. Depositing USDT into Yearn vault Parameters: * `amount`: Amount to invest * `minOutputAfterInvestment`: Minimum expected shares Returns: * `depositedAmount`: Amount of tokens received #### \_divest ```solidity function _divest(uint256 shares) internal override returns (uint256 withdrawn) ``` Withdraws assets by: 1. Redeeming from Yearn vault 2. Converting USDT to USDCe through zapper Parameters: * `shares`: Amount of shares to withdraw Returns: * `withdrawn`: Amount of assets received ### Internal View Functions #### \_shareValue ```solidity function _shareValue(uint256 shares) internal view override returns (uint256 _assets) ``` Calculates underlying value including conversion rate. Parameters: * `shares`: Share amount Returns: * Underlying asset value #### \_sharesForAmount ```solidity function _sharesForAmount(uint256 amount) internal view override returns (uint256 _shares) ``` Calculates shares needed including spot price conversion. Parameters: * `amount`: Asset amount Returns: * Required shares #### \_spotPriceDy ```solidity function _spotPriceDy(uint256 i, uint256 amount) internal view returns (uint256 _spotDy) ``` Calculates spot price conversion without slippage. Parameters: * `i`: Direction (1: USDC->USDT, 2: USDT->USDC) * `amount`: Amount to convert Returns: * Converted amount at spot price --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://devs.maxapy.io/maxapy-erc4626/strategies/polygon-usdc.e/yearn/yearnaavev3usdtlenderstrategy.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.