[feat] add MCP file browsing and cancellable transfers

libs/controller/include/controller_files.h

@@ -0,0 +1,31 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-11-06
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _CONTROLLER_FILES_H_
+#define _CONTROLLER_FILES_H_
+
+#include <functional>
+#include <memory>
+#include <nlohmann/json.hpp>
+#include <string>
+
+namespace crossdesk {
+class ControllerFiles {
+public:
+  using Send = std::function<bool(const char *, const std::string &)>;
+  explicit ControllerFiles(Send send);
+  ~ControllerFiles();
+  nlohmann::json Command(const nlohmann::json &request);
+  void Message(nlohmann::json message);
+  void Receive(const char *data, size_t size, bool acknowledgement);
+  void Tick();
+private:
+  struct State;
+  std::unique_ptr<State> state_;
+};
+} // namespace crossdesk
+
+#endif