fix: return value on temp kernel

src/factory/TempKernel.sol

@@ -176,9 +176,29 @@ contract TempKernel is EIP712, IAccount {
         if (address(validator) != address(0)) {
             validator.enable(getStorage().validatorData);
         }
-
-        (bool success, bytes memory ret) = _newImplementation.delegatecall(msg.data);
-        require(success, string(ret));
+
+        assembly {
+            // Copy msg.data. We take full control of memory in this inline assembly
+            // block because it will not return to Solidity code. We overwrite the
+            // Solidity scratch pad at memory position 0.
+            calldatacopy(0, 0, calldatasize())
+
+            // Call the implementation.
+            // out and outsize are 0 because we don't know the size yet.
+            let result := delegatecall(gas(), _newImplementation, 0, calldatasize(), 0, 0)
+
+            // Copy the returned data.
+            returndatacopy(0, 0, returndatasize())
+
+            switch result
+            // delegatecall returns 0 on error.
+            case 0 {
+                revert(0, returndatasize())
+            }
+            default {
+                return(0, returndatasize())
+            }
+        }
     }
 
     // WARTNING: this function is NOT VIEW
@@ -223,6 +243,8 @@ contract TempKernel is EIP712, IAccount {
             ret := ptr
             success := result
         }
-        require(success, string(ret));
+        if(!success) {
+            revert(string(ret));
+        }
     }
 }

src/test/TestERC721.sol

@@ -9,4 +9,8 @@ contract TestERC721 is ERC721 {
     function mint(address _to, uint256 _id) external {
         _mint(_to, _id);
     }
+
+    function safeMint(address _to, uint256 _id) external {
+        _safeMint(_to, _id);
+    }
 }

test/foundry/Kernel.test.sol

@@ -2,13 +2,13 @@
 pragma solidity ^0.8.0;
 
 import "src/factory/KernelFactory.sol";
-import "src/factory/TempKernel.sol";
 import "src/factory/ECDSAKernelFactory.sol";
 import "src/Kernel.sol";
 import "src/validator/ECDSAValidator.sol";
 import "src/factory/EIP1967Proxy.sol";
 // test artifacts
 import "src/test/TestValidator.sol";
+import "src/test/TestERC721.sol";
 // test utils
 import "forge-std/Test.sol";
 import {ERC4337Utils} from "./ERC4337Utils.sol";
@@ -63,6 +63,13 @@ contract KernelTest is Test {
         assertEq(storage_.owner, owner);
     }
 
+    function test_erc721_receive() external {
+        Kernel kernel2 = Kernel(payable(address(ecdsaFactory.createAccount(owner, 1))));
+        TestERC721 nft = new TestERC721();
+        nft.safeMint(address(kernel2), 1);
+        assertEq(nft.ownerOf(1), address(kernel2));
+    }
+
     function test_validate_signature() external {
         Kernel kernel2 = Kernel(payable(address(ecdsaFactory.createAccount(owner, 1))));
         bytes32 hash = keccak256(abi.encodePacked("hello world"));