[refactor] organize GUI code by responsibility

src/gui/features/input/keyboard_controller.h

@@ -0,0 +1,63 @@
+#ifndef CROSSDESK_GUI_KEYBOARD_CONTROLLER_H_
+#define CROSSDESK_GUI_KEYBOARD_CONTROLLER_H_
+
+#include <cstdint>
+#include <mutex>
+#include <string>
+#include <unordered_map>
+
+#include "device_controller.h"
+
+namespace crossdesk {
+
+class GuiRuntime;
+
+// Synchronizes local and remote keyboard state, including heartbeat recovery
+// for keys whose key-up event was lost during a connection interruption.
+class KeyboardController {
+public:
+  explicit KeyboardController(GuiRuntime &owner);
+
+  int SendKeyCommand(int key_code, bool is_down, uint32_t scan_code = 0,
+                     bool extended = false);
+  void ForceReleasePressedKeys();
+  void SendHeartbeat(bool force);
+  void ApplyRemoteEvent(const std::string &remote_id,
+                        const RemoteAction &remote_action);
+  void ApplyRemoteState(const std::string &remote_id,
+                        const RemoteAction &remote_action);
+  void ReleaseRemotePressedKeys(const std::string &remote_id,
+                                const char *reason);
+  void CheckRemoteTimeouts();
+
+private:
+  struct PressedKey {
+    int key_code = 0;
+    uint32_t scan_code = 0;
+    bool extended = false;
+  };
+
+  struct RemoteState {
+    std::unordered_map<int, PressedKey> pressed_keys;
+    uint32_t last_seq = 0;
+    uint32_t last_seen_tick = 0;
+    bool keyboard_state_seen = false;
+  };
+
+  void TrackPressedKey(int key_code, bool is_down, uint32_t scan_code,
+                       bool extended);
+  bool InjectRemoteKey(int key_code, bool is_down, uint32_t scan_code,
+                       bool extended);
+
+  GuiRuntime &owner_;
+  std::unordered_map<int, PressedKey> pressed_keys_;
+  std::mutex pressed_keys_mutex_;
+  uint32_t state_sequence_ = 0;
+  uint32_t last_heartbeat_tick_ = 0;
+  std::unordered_map<std::string, RemoteState> remote_states_;
+  std::mutex remote_states_mutex_;
+};
+
+} // namespace crossdesk
+
+#endif // CROSSDESK_GUI_KEYBOARD_CONTROLLER_H_