feat: add Wrapped Staked Eth hook

src/base/hooks/BaseTokenWrapperHook.sol

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: MIT
 pragma solidity ^0.8.0;
 
 import {

src/hooks/WETHHook.sol

@@ -13,8 +13,6 @@ contract WETHHook is BaseTokenWrapperHook {
     /// @notice The WETH9 contract
     WETH public immutable weth;
 
-    error WithdrawFailed();
-
     /// @notice Creates a new WETH wrapper hook
     /// @param _manager The Uniswap V4 pool manager
     /// @param _weth The WETH9 contract address

src/hooks/WstETHHook.sol

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import {ERC20} from "solmate/src/tokens/ERC20.sol";
+import {IPoolManager} from "@uniswap/v4-core/src/interfaces/IPoolManager.sol";
+import {Currency, CurrencyLibrary} from "@uniswap/v4-core/src/types/Currency.sol";
+import {BaseTokenWrapperHook} from "../base/hooks/BaseTokenWrapperHook.sol";
+import {IWstETH} from "../interfaces/external/IWstETH.sol";
+
+/// @title Wrapped Staked ETH (wstETH) Hook
+/// @notice Hook for wrapping/unwrapping stETH/wstETH in Uniswap V4 pools
+/// @dev Implements dynamic exchange rate wrapping/unwrapping between stETH and wstETH
+/// @dev wstETH represents stETH with accrued staking rewards, maintaining a dynamic exchange rate
+contract WstETHHook is BaseTokenWrapperHook {
+    /// @notice The wstETH contract used for wrapping/unwrapping operations
+    IWstETH public immutable wstETH;
+
+    /// @notice Creates a new wstETH wrapper hook
+    /// @param _manager The Uniswap V4 pool manager
+    /// @param _wsteth The wstETH contract address
+    /// @dev Initializes with wstETH as wrapper token and stETH as underlying token
+    constructor(IPoolManager _manager, IWstETH _wsteth)
+        BaseTokenWrapperHook(
+            _manager,
+            Currency.wrap(address(_wsteth)), // wrapper token is wsteth
+            Currency.wrap(_wsteth.stETH()) // underlying token is stETH
+        )
+    {
+        wstETH = _wsteth;
+        ERC20(Currency.unwrap(underlyingCurrency)).approve(address(wstETH), type(uint256).max);
+    }
+
+    /// @inheritdoc BaseTokenWrapperHook
+    /// @notice Wraps stETH to wstETH
+    /// @param underlyingAmount Amount of stETH to wrap
+    /// @return Amount of wstETH received
+    function _deposit(uint256 underlyingAmount) internal override returns (uint256) {
+        return wstETH.wrap(underlyingAmount);
+    }
+
+    /// @inheritdoc BaseTokenWrapperHook
+    /// @notice Unwraps wstETH to stETH
+    /// @param wrapperAmount Amount of wstETH to unwrap
+    /// @return Amount of stETH received
+    function _withdraw(uint256 wrapperAmount) internal override returns (uint256) {
+        return wstETH.unwrap(wrapperAmount);
+    }
+
+    /// @inheritdoc BaseTokenWrapperHook
+    /// @notice Calculates how much stETH is needed to receive a specific amount of wstETH
+    /// @param wrappedAmount Desired amount of wstETH
+    /// @return Amount of stETH required
+    /// @dev Uses current stETH/wstETH exchange rate for calculation
+    function _getWrapInputRequired(uint256 wrappedAmount) internal view override returns (uint256) {
+        return wstETH.getStETHByWstETH(wrappedAmount);
+    }
+
+    /// @inheritdoc BaseTokenWrapperHook
+    /// @notice Calculates how much wstETH is needed to receive a specific amount of stETH
+    /// @param underlyingAmount Desired amount of stETH
+    /// @return Amount of wstETH required
+    /// @dev Uses current stETH/wstETH exchange rate for calculation
+    function _getUnwrapInputRequired(uint256 underlyingAmount) internal view override returns (uint256) {
+        return wstETH.getWstETHByStETH(underlyingAmount);
+    }
+
+    /// @notice Required to receive ETH from unwrapping operations
+    /// @dev Needed for protocol integrations that might send ETH to this contract
+    receive() external payable {}
+}

src/interfaces/external/IWstETH.sol

@@ -0,0 +1,15 @@
+// SPDX-FileCopyrightText: 2021 Lido <[email protected]>
+// https://github.com/lidofinance/core/blob/master/contracts/0.6.12/WstETH.sol
+
+// SPDX-License-Identifier: GPL-3.0
+
+/* See contracts/COMPILERS.md */
+pragma solidity ^0.8.0;
+
+interface IWstETH {
+    function wrap(uint256 _stETHAmount) external returns (uint256);
+    function unwrap(uint256 _wstETHAmount) external returns (uint256);
+    function getStETHByWstETH(uint256 _wstETHAmount) external view returns (uint256);
+    function getWstETHByStETH(uint256 _stETHAmount) external view returns (uint256);
+    function stETH() external view returns (address);
+}