YearnUSDTStrategy

Overview

The YearnUSDTStrategy contract is a strategy that supplies USDT into a Yearn V2 Vault to earn yield. It handles conversions between the underlying asset and USDT through Curve's 3pool and includes safety margins for liquidations.

Constants

ICurveTriPool public constant triPool = ICurveTriPool(CURVE_3POOL_POOL_MAINNET);  // Curve's 3pool
address constant usdt = USDT_MAINNET;                                              // USDT token address

Functions

Initialization Functions

initialize

function initialize(
    IMaxApyVault _vault,
    address[] calldata _keepers,
    bytes32 _strategyName,
    address _strategist,
    IYVault _yVault
) public virtual override initializer

Initializes the strategy with required components.

Parameters:

• _vault: MaxApy vault address

• _keepers: Array of keeper addresses

• _strategyName: Name of the strategy

• _strategist: Strategist address

• _yVault: Yearn V2 vault address

View Functions

previewLiquidate

function previewLiquidate(uint256 requestedAmount) public view override returns (uint256 liquidatedAmount)

Simulates withdrawal with 1% safety margin.

Parameters:

• requestedAmount: Amount to withdraw

Returns:

• liquidatedAmount: Expected output amount

previewLiquidateExact

function previewLiquidateExact(uint256 liquidatedAmount) public view virtual override returns (uint256 requestedAmount)

Calculates input needed with 2% buffer.

Parameters:

• liquidatedAmount: Desired output amount

Returns:

• requestedAmount: Required input amount

Internal Core Functions

_invest

function _invest(uint256 amount, uint256 minOutputAfterInvestment) internal override returns (uint256 depositedAmount)

Invests assets by:

1. Swapping underlying to USDT through Curve

2. Depositing USDT into Yearn vault

Parameters:

• amount: Amount to invest

• minOutputAfterInvestment: Minimum expected shares

Returns:

• depositedAmount: Amount of tokens received

_divest

function _divest(uint256 shares) internal override returns (uint256 withdrawn)

Withdraws assets by:

1. Withdrawing USDT from Yearn vault

2. Swapping USDT to underlying through Curve

Parameters:

• shares: Amount of shares to withdraw

Returns:

• withdrawn: Amount of assets received

Internal View Functions

_shareValue

function _shareValue(uint256 shares) internal view override returns (uint256)

Calculates underlying value including Curve conversion.

Parameters:

• shares: Share amount

Returns:

• Underlying value

_sharesForAmount

function _sharesForAmount(uint256 amount) internal view override returns (uint256 shares)

Calculates shares needed including Curve conversion.

Parameters:

• amount: Asset amount

Returns:

• Required shares

Key Features:

• Uses Curve's 3pool for token conversions

• Sets 1M USD maximum trade size

• Sets minimum trade size to 0.01 token units

• Includes safety margins for withdrawals

• Handles conversions between USDT and underlying asset