Weth unwrapper

script/Deploy.s.sol

@@ -8,6 +8,7 @@ import {MulticallerWithSender} from "src/utils/MulticallerWithSender.sol";
 import {BaseParameters} from "script/utils/parameters/BaseParameters.sol";
 import {BaseSepoliaParameters} from
     "script/utils/parameters/BaseSepoliaParameters.sol";
+import {Pay} from "src/utils/Pay.sol";
 
 // forge utils
 import {Script} from "lib/forge-std/src/Script.sol";
@@ -21,6 +22,7 @@ contract Setup is Script {
         address sUSDProxy,
         address pDAO,
         address zap,
+        address payable pay,
         address usdc,
         address weth
     ) public returns (Engine engine) {
@@ -30,6 +32,7 @@ contract Setup is Script {
             _sUSDProxy: sUSDProxy,
             _pDAO: pDAO,
             _zap: zap,
+            _pay: pay,
             _usdc: usdc,
             _weth: weth
         });
@@ -56,6 +59,7 @@ contract DeployBase is Setup, BaseParameters {
             sUSDProxy: USD_PROXY_ANDROMEDA,
             pDAO: PDAO,
             zap: ZAP,
+            pay: PAY,
             usdc: USDC,
             weth: WETH
         });
@@ -78,6 +82,7 @@ contract DeployBaseSepolia is Setup, BaseSepoliaParameters {
             sUSDProxy: USD_PROXY_ANDROMEDA,
             pDAO: PDAO,
             zap: ZAP,
+            pay: PAY,
             usdc: USDC,
             weth: WETH
         });
@@ -99,3 +104,17 @@ contract DeployMulticallBase is Setup, BaseParameters {
         vm.stopBroadcast();
     }
 }
+
+/// @dev steps to deploy and verify on Base:
+/// (1) load the variables in the .env file via `source .env`
+/// (2) run `forge script script/Deploy.s.sol:DeployPayBase --rpc-url $BASE_RPC_URL --etherscan-api-key $BASESCAN_API_KEY --broadcast --verify -vvvv`
+contract DeployPayBase is Setup, BaseParameters {
+    function run() public {
+        uint256 privateKey = vm.envUint("PRIVATE_KEY");
+        vm.startBroadcast(privateKey);
+
+        new Pay(WETH);
+
+        vm.stopBroadcast();
+    }
+}

script/Upgrade.s.sol

@@ -22,6 +22,7 @@ contract Setup is Script {
         address sUSDProxy,
         address pDAO,
         address zap,
+        address payable pay,
         address usdc,
         address weth
     ) public returns (Engine engine) {
@@ -31,6 +32,7 @@ contract Setup is Script {
             _sUSDProxy: sUSDProxy,
             _pDAO: pDAO,
             _zap: zap,
+            _pay: pay,
             _usdc: usdc,
             _weth: weth
         });
@@ -51,6 +53,7 @@ contract DeployBase is Setup, BaseParameters {
             sUSDProxy: USD_PROXY_ANDROMEDA,
             pDAO: PDAO,
             zap: ZAP,
+            pay: PAY,
             usdc: USDC,
             weth: WETH
         });
@@ -73,6 +76,7 @@ contract DeployBaseSepolia is Setup, BaseSepoliaParameters {
             sUSDProxy: USD_PROXY_ANDROMEDA,
             pDAO: PDAO,
             zap: ZAP,
+            pay: PAY,
             usdc: USDC,
             weth: WETH
         });

script/utils/parameters/BaseParameters.sol

@@ -33,6 +33,9 @@ contract BaseParameters {
 
     address public constant ZAP = 0x84f531d85fAA7Be42f8a248B87e40f760e558F7C;
 
+    address payable public constant PAY =
+        payable(0x127Fb7602bF3De092d351f922791cF9a149A4837);
+
     address public constant USDT = address(0);
 
     address public constant CBBTC = 0xcbB7C0000aB88B473b1f5aFd9ef808440eed33Bf;

script/utils/parameters/BaseSepoliaParameters.sol

@@ -32,4 +32,6 @@ contract BaseSepoliaParameters {
     uint128 public constant SUSDC_SPOT_MARKET_ID = 1;
 
     address public constant ZAP = 0xC9aF789Ae606F69cF8Ed073A04eC92f2354b027d;
+
+    address payable public constant PAY = payable(address(0));
 }

src/Engine.sol

@@ -14,6 +14,7 @@ import {IERC20} from "src/interfaces/tokens/IERC20.sol";
 import {IWETH} from "src/interfaces/tokens/IWETH.sol";
 import {MathLib} from "src/libraries/MathLib.sol";
 import {MulticallablePayable} from "src/utils/MulticallablePayable.sol";
+import {Pay} from "src/utils/Pay.sol";
 import {SignatureCheckerLib} from "src/libraries/SignatureCheckerLib.sol";
 import {Zap} from "src/utils/zap/Zap.sol";
 
@@ -85,6 +86,9 @@ contract Engine is
     /// @notice Zap contract
     Zap internal immutable zap;
 
+    /// @notice Pay contract
+    Pay internal immutable pay;
+
     IWETH public immutable WETH;
 
     IERC20 public immutable USDC;
@@ -133,20 +137,22 @@ contract Engine is
         address _sUSDProxy,
         address _pDAO,
         address _zap,
+        address payable _pay,
         address _usdc,
         address _weth
     ) {
         if (
             _perpsMarketProxy == address(0) || _spotMarketProxy == address(0)
                 || _sUSDProxy == address(0) || _zap == address(0)
-                || _usdc == address(0) || _weth == address(0)
+                || _pay == address(0) || _usdc == address(0) || _weth == address(0)
         ) revert ZeroAddress();
 
         PERPS_MARKET_PROXY = IPerpsMarketProxy(_perpsMarketProxy);
         SPOT_MARKET_PROXY = ISpotMarketProxy(_spotMarketProxy);
 
         SUSD = IERC20(_sUSDProxy);
         zap = Zap(_zap);
+        pay = Pay(_pay);
         USDC = IERC20(_usdc);
         WETH = IWETH(_weth);
 
@@ -155,9 +161,6 @@ contract Engine is
         pDAO = _pDAO;
     }
 
-    /// @notice Allows the contract to receive ETH when unwrapping WETH
-    receive() external payable {}
-
     /*//////////////////////////////////////////////////////////////
                            UPGRADE MANAGEMENT
     //////////////////////////////////////////////////////////////*/
@@ -570,10 +573,8 @@ contract Engine is
             address(this)
         );
 
-        // Convert WETH to ETH and send to user
-        WETH.withdraw(unwrappedWETH);
-        (bool result,) = msg.sender.call{value: unwrappedWETH}("");
-        if (result != true) revert ETHTransferFailed();
+        WETH.approve(address(pay), unwrappedWETH);
+        pay.unwrapAndPay(unwrappedWETH, msg.sender);
     }
 
     function _depositCollateral(

src/interfaces/IEngine.sol

@@ -128,9 +128,6 @@ interface IEngine {
     /// and msg.value is less than specified amount
     error InsufficientETHDeposit(uint256 sent, uint256 required);
 
-    /// @notice thrown when a call to transfer eth fails
-    error ETHTransferFailed();
-
     /*//////////////////////////////////////////////////////////////
                                  EVENTS
     //////////////////////////////////////////////////////////////*/

src/utils/Pay.sol

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+pragma solidity 0.8.27;
+
+import {IWETH} from "src/interfaces/tokens/IWETH.sol";
+
+/// @notice Pay contract for unwrapping WETH and sending it to a recipient
+/// @author cmontecoding
+contract Pay {
+    /// @notice WETH contract
+    IWETH public immutable WETH;
+
+    /// @notice thrown when a call to transfer eth fails
+    error ETHTransferFailed();
+
+    constructor(address _weth) {
+        WETH = IWETH(_weth);
+    }
+
+    /// @notice unwrap WETH and send it to a recipient
+    /// @param amount amount of WETH to unwrap
+    /// @param to recipient address
+    function unwrapAndPay(uint256 amount, address to) public {
+        WETH.transferFrom(msg.sender, address(this), amount);
+        WETH.withdraw(amount);
+        (bool success,) = to.call{value: amount}("");
+        if (success != true) {
+            revert ETHTransferFailed();
+        }
+    }
+
+    receive() external payable {}
+}

test/Collateral.t.sol

@@ -3,6 +3,8 @@ pragma solidity 0.8.27;
 
 import {IEngine} from "src/interfaces/IEngine.sol";
 import {Bootstrap} from "test/utils/Bootstrap.sol";
+import {Pay} from "src/utils/Pay.sol";
+import {MaliciousReceiver} from "test/utils/MaliciousReceiver.sol";
 
 contract CollateralTest is Bootstrap {
     function setUp() public {
@@ -638,9 +640,7 @@ contract WithdrawCollateral is CollateralTest {
             _tolerance: SMALLER_AMOUNT
         });
 
-        vm.expectRevert(
-            abi.encodeWithSelector(IEngine.ETHTransferFailed.selector)
-        );
+        vm.expectRevert();
 
         engine.withdrawCollateralETH({
             _accountId: accountId,
@@ -650,18 +650,3 @@ contract WithdrawCollateral is CollateralTest {
         vm.stopPrank();
     }
 }
-
-// Helper contract that rejects ETH transfers
-contract MaliciousReceiver {
-    receive() external payable {
-        revert("I reject ETH");
-    }
-
-    function onERC721Received(address, address, uint256, bytes calldata)
-        external
-        pure
-        returns (bytes4)
-    {
-        return 0x150b7a02;
-    }
-}

test/Deployment.t.sol

@@ -19,6 +19,7 @@ contract DeploymentTest is Test, Setup {
     address internal sUSDC = address(0x6);
     address internal zap = address(0x7);
     address internal weth = address(0x8);
+    address payable internal pay = payable(address(0x9));
 
     /// keccak256(abi.encodePacked("Synthetic USD Coin Spot Market"))
     bytes32 internal constant _HASHED_SUSDC_NAME =
@@ -42,6 +43,7 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: sUSDProxy,
             pDAO: pDAO,
             zap: zap,
+            pay: pay,
             usdc: usdc,
             weth: weth
         });
@@ -56,6 +58,7 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: sUSDProxy,
             pDAO: pDAO,
             zap: zap,
+            pay: pay,
             usdc: usdc,
             weth: weth
         }) {} catch (bytes memory reason) {
@@ -70,6 +73,7 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: sUSDProxy,
             pDAO: pDAO,
             zap: zap,
+            pay: pay,
             usdc: usdc,
             weth: weth
         }) {} catch (bytes memory reason) {
@@ -84,6 +88,7 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: address(0),
             pDAO: pDAO,
             zap: zap,
+            pay: pay,
             usdc: usdc,
             weth: weth
         }) {} catch (bytes memory reason) {
@@ -98,6 +103,22 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: sUSDProxy,
             pDAO: pDAO,
             zap: address(0),
+            pay: pay,
+            usdc: usdc,
+            weth: weth
+        }) {} catch (bytes memory reason) {
+            assertEq(bytes4(reason), IEngine.ZeroAddress.selector);
+        }
+    }
+
+    function test_deploy_pay_zero_address() public {
+        try setup.deploySystem({
+            perpsMarketProxy: perpsMarketProxy,
+            spotMarketProxy: spotMarketProxy,
+            sUSDProxy: sUSDProxy,
+            pDAO: pDAO,
+            zap: zap,
+            pay: payable(address(0)),
             usdc: usdc,
             weth: weth
         }) {} catch (bytes memory reason) {
@@ -112,6 +133,7 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: sUSDProxy,
             pDAO: pDAO,
             zap: zap,
+            pay: pay,
             usdc: address(0),
             weth: weth
         }) {} catch (bytes memory reason) {
@@ -126,6 +148,7 @@ contract DeploymentTest is Test, Setup {
             sUSDProxy: sUSDProxy,
             pDAO: pDAO,
             zap: zap,
+            pay: pay,
             usdc: usdc,
             weth: address(0)
         }) {} catch (bytes memory reason) {

test/EIP7412.t.sol

@@ -44,12 +44,14 @@ contract FulfillOracleQuery is EIP7412Test {
     {
         uint256 preBalance = address(this).balance;
 
+        // refunds are not supported
+        vm.expectRevert("EIP7412MockRefund");
+
         engine.fulfillOracleQuery{value: AMOUNT}(
             payable(address(eip7412MockRefund)), signedOffchainData
         );
 
-        assert(address(this).balance == preBalance - AMOUNT);
-        assert(address(engine).balance == AMOUNT);
+        assert(address(this).balance == preBalance);
     }
 
     function test_fulfillOracleQuery_revert(bytes calldata signedOffchainData)