feat: UniswapXFiller skeleton

foundry/src/uniswap_x/IReactor.sol

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: BUSL-1.1
+pragma solidity ^0.8.26;
+
+import {SignedOrder} from "./IStructs.sol";
+import {IReactorCallback} from "./IReactorCallback.sol";
+
+/// @notice Interface for order execution reactors
+interface IReactor {
+    /// @notice Execute a single order
+    /// @param order The order definition and valid signature to execute
+    function execute(SignedOrder calldata order) external payable;
+
+    /// @notice Execute a single order using the given callback data
+    /// @param order The order definition and valid signature to execute
+    function executeWithCallback(
+        SignedOrder calldata order,
+        bytes calldata callbackData
+    ) external payable;
+
+    /// @notice Execute the given orders at once
+    /// @param orders The order definitions and valid signatures to execute
+    function executeBatch(SignedOrder[] calldata orders) external payable;
+
+    /// @notice Execute the given orders at once using a callback with the given callback data
+    /// @param orders The order definitions and valid signatures to execute
+    /// @param callbackData The callbackData to pass to the callback
+    function executeBatchWithCallback(
+        SignedOrder[] calldata orders,
+        bytes calldata callbackData
+    ) external payable;
+}