Update

Assets/Scripts/UI/LobbyController.cs

@@ -236,7 +236,13 @@ namespace Hallucinate.UI
                 : null;
 
             bool success = await spawner.StartHost(id, name, pass);
-            if (success) ShowLounge(name);
+            if (success)
+            {
+                ShowLounge(name);
+                // Explicitly push the LobbyController to ensure it's the active UI screen.
+                // This helps prevent unintended navigation away from the lounge.
+                await uiManager.Push<LobbyController>();
+            }
         }
 
         private void UpdateRoomList(List<SessionInfo> sessions)
@@ -319,12 +325,12 @@ namespace Hallucinate.UI
             BasicSpawner.Instance?.StartGame();
         }
 
-        private void OnLeaveLoungeClicked()
+        private async void OnLeaveLoungeClicked()
         {
             var runner = Object.FindFirstObjectByType<NetworkRunner>();
             if (runner != null)
             {
-                runner.Shutdown();
+                await runner.Shutdown();
             }
             if (_playerDataManager != null)
             {
@@ -355,7 +361,7 @@ namespace Hallucinate.UI
                 }
             }
 
-            if (_playerDataManager == null || !_playerDataManager.Object.IsValid) return;
+            if (_playerDataManager == null || _playerDataManager.Object == null || !_playerDataManager.Object.IsValid) return;
 
             PlayerRef hostRef = PlayerRef.None;
             PlayerRef guestRef = PlayerRef.None;

Assets/Scripts/UI/UIManager.cs

@@ -63,6 +63,9 @@ namespace Hallucinate.UI
 
         private const string UI_SCALE_KEY = "UIScale";
 
+        [Header("Development Settings")]
+        [SerializeField] private bool allowMultipleInstances = true;
+
         private void Awake()
         {
             if (Instance != null && Instance != this)
@@ -73,6 +76,19 @@ namespace Hallucinate.UI
             Instance = this;
             DontDestroyOnLoad(gameObject);
 
+            // Single instance guard
+            if (!Application.isEditor && !allowMultipleInstances)
+            {
+                var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
+                var processes = System.Diagnostics.Process.GetProcessesByName(currentProcess.ProcessName);
+                if (processes.Length > 1)
+                {
+                    Debug.LogError("[UIManager] Another instance is already running. Quitting to prevent save conflict.");
+                    Application.Quit();
+                    return;
+                }
+            }
+
             _uiDocument = GetComponent<UIDocument>();
             UnityEngine.Cursor.visible = false;
             
@@ -92,10 +108,10 @@ namespace Hallucinate.UI
         public void SetUIScale(float scale)
         {
             if (_uiDocument == null || _uiDocument.panelSettings == null) return;
-            
+
             // Unity UI Toolkit dùng panelSettings để điều khiển tỉ lệ
-            // Chúng ta thay đổi scale multiplier
-            _uiDocument.panelSettings.scale = scale;
+            // Chúng ta thay đổi scale multiplier. Mặc định 1.0 sẽ tương ứng với visual scale là 1.3
+            _uiDocument.panelSettings.scale = scale * 1.3f;
             PlayerPrefs.SetFloat(UI_SCALE_KEY, scale);
             PlayerPrefs.Save();
         }
@@ -105,7 +121,6 @@ namespace Hallucinate.UI
             float savedScale = PlayerPrefs.GetFloat(UI_SCALE_KEY, 1.0f);
             SetUIScale(savedScale);
         }
-
         private void Start()
         {
             if (_uiDocument == null) _uiDocument = GetComponent<UIDocument>();