Respond to audit feedback

snapshots/Solver7702DelegateTest.json

@@ -6,6 +6,7 @@
   "approved caller target payload - success - forwards": "31104",
   "approved caller target return data - success - bubbles return data": "24915",
   "approved caller target revert data - reverts - bubbles non-empty data": "25584",
-  "unauthorized caller - success - receives ETH": "21199",
+  "self call no value - success - bypasses auth": "21930",
+  "unauthorized caller - success - receives ETH": "21221",
   "unauthorized caller no value - reverts - unauthorized": "21930"
 }

src/Solver7702Delegate.sol

@@ -43,7 +43,12 @@ contract Solver7702Delegate {
         ) return _callThrough();
 
         // Accept ETH from anyone, even if unauthorized
-        if (msg.value > 0) return;
+        // We do this to preserve the behavior of an EOA address (which doesn't revert when ETH is sent) as much as
+        // reasonably possible. As it is unlikely that a contract will treat a solver address as a contract and
+        // simultaneously send ETH, this should be reasonbly safe.
+        // We also return gracefully on calls to self to prevent compatibility errors with existing solvers that expect
+        // to be able to cancel their transaction by call to self.
+        if (msg.value > 0 || msg.sender == address(this)) return;
         revert Unauthorized(msg.sender);
     }
 
@@ -55,9 +60,10 @@ contract Solver7702Delegate {
         address target = address(bytes20(msg.data[0:20]));
 
         assembly {
-            // Extract calldata in range (target, len(msg.data)).
-            // We take full control of memory in this inline assembly block because it will not return to Solidity code.
-            // This is why we overwrite the Solidity scratch pad at memory position 0.
+            // Extract calldata in range (target, len(msg.data)). For efficiency and simplicity, we overwrite from
+            // memory position 0 (the solidity scratch pad). If `calldatasize()` is larger than 84, the Solidity free
+            // memory pointer and "zero" slot may also be overwritten with arbitrary data.
+            // Since we do not return to Solidity code, this is not a problem.
             calldatacopy(0x00, 20, sub(calldatasize(), 20))
 
             // Call the implementation

test/Solver7702Delegate.t.sol

@@ -121,6 +121,18 @@ contract Solver7702DelegateTest is BaseTest {
         assertEq(returnData, expectedReturnData, "target return data should bubble");
     }
 
+    function test_unit_fallback_success_selfCallDoesNotRevert() public {
+        bytes memory payload = hex"12345678";
+
+        vm.prank(address(delegateContract));
+        (bool success, bytes memory returnData) =
+            address(delegateContract).call(_packedCalldata(fallbackTarget, payload));
+        vm.snapshotGasLastCall("self call no value - success - bypasses auth");
+
+        assertTrue(success, "self call should succeed");
+        assertEq(returnData.length, 0, "self call should return empty response");
+    }
+
     function test_unit_fallback_revertsWith_UnauthorizedCaller() public {
         bytes memory payload = hex"12345678";