fix: 完成5项核心BUG修复，提升应用稳定性

- 修复显示器选择器拒绝同步后回退索引错误
- 修复定时调度启动时Gamma前置状态未保存问题
- 修复非轻量模式下Gamma重复应用问题
- 修复轻量模式退出后UI状态未刷新问题
- 修复per-display模式下Gamma开关状态不更新问题

Author: SummerRay160

LumiShift/BackgroundService.cs

@@ -61,6 +61,8 @@ internal MonitorManager MonitorManager
         internal bool IsExiting => _exiting;
         internal bool ScheduleManualOverride => _scheduleManualOverride;
         private bool _lightweightMode;
+        private bool _displayChangedInLightweight;
+        private bool _scheduleChangedInLightweight;
         private Timer _lightweightGcTimer;
 
         private Form1 MainForm
@@ -132,6 +134,12 @@ public BackgroundService()
             {
                 _scheduleTimer.Start();
                 ScheduleTimer_Tick(null, null);
+                _preScheduleGammaEnabled = Settings.GammaEnabled;
+                _preScheduleGammaRScale = Settings.GammaRScale;
+                _preScheduleGammaGScale = Settings.GammaGScale;
+                _preScheduleGammaBScale = Settings.GammaBScale;
+                _preScheduleGammaValue = Settings.GammaValue;
+                _preScheduleMasterBrightness = Settings.MasterBrightness;
             }
 
             ApplyGammaToSystem();
@@ -833,13 +841,14 @@ internal void ScheduleTimer_Tick(object sender, EventArgs e)
                     return;
                 }
 
-                ApplyGammaToSystem();
                 if (_lightweightMode)
                 {
                     _lastScheduleMode = targetMode;
+                    _scheduleChangedInLightweight = true;
                     ApplyScheduleMonitorPresets(targetSegment);
                     return;
                 }
+
                 SettingsStore.SaveSettings(Settings);
                 UpdateTrayMenu();
                 _lastScheduleMode = targetMode;
@@ -1100,13 +1109,15 @@ private void HandleDisplayChange()
         {
             if (_monitorManager == null) return;
 
-            var removedIds = _monitorManager.RefreshMonitors();
-            CleanupStaleSettings(removedIds);
             if (_lightweightMode)
             {
+                _displayChangedInLightweight = true;
                 _trayMenuNeedsRebuild = true;
                 return;
             }
+
+            var removedIds = _monitorManager.RefreshMonitors();
+            CleanupStaleSettings(removedIds);
             if (!Form1IsOpen())
             {
                 if (_trayMenuOpen)
@@ -1196,19 +1207,32 @@ public void ShowMainWindow()
             if (_lightweightMode)
             {
                 _lightweightMode = false;
+                var displayChanged = _displayChangedInLightweight;
+                _displayChangedInLightweight = false;
                 _lightweightGcTimer?.Stop();
                 _lightweightGcTimer?.Dispose();
                 _lightweightGcTimer = null;
                 _microGcTimer?.Stop();
                 _microGcTimer?.Dispose();
                 _microGcTimer = null;
                 if (_monitorManager != null)
-                    _monitorManager.ExitLightweightMode();
+                {
+                    if (displayChanged)
+                        _monitorManager.RefreshMonitors();
+                    else
+                        _monitorManager.ExitLightweightMode();
+                }
                 if (_scheduleTimer != null)
                     _scheduleTimer.Interval = ScheduleTimerIntervalNormal;
                 if (_messageWindow == null)
                     _messageWindow = new MessageWindow(this);
+                _healthCheckTimer?.Start();
                 GcHelper.CollectFull();
+                if (_scheduleChangedInLightweight)
+                {
+                    _scheduleChangedInLightweight = false;
+                    ScheduleStateChanged?.Invoke();
+                }
             }
 
             MainForm = new Form1(this);
@@ -1227,13 +1251,15 @@ internal void EnterAppLightweightMode()
         {
             if (_lightweightMode) return;
             _lightweightMode = true;
+            _scheduleChangedInLightweight = false;
             Form1.CleanupStaticFields();
             Controls.GdiCache.Clear();
             GammaController.TrimCache();
             _parsedSegments = null;
             _parsedSegmentsHash = 0;
             _messageWindow?.Dispose();
             _messageWindow = null;
+            _healthCheckTimer?.Stop();
             if (_monitorManager != null)
                 _monitorManager.EnterLightweightMode();
             if (_scheduleTimer != null)

LumiShift/Form1.Designer.cs

@@ -81,6 +81,7 @@ public partial class Form1 : Form
         private bool _isPopulatingComboBox;
         private bool _isUpdatingSchedule;
         private string _currentPresetName;
+        private int _previousMonitorSelectedIndex;
         private Timer _initTimer;
 
         private static Icon LoadAppIcon()
@@ -1094,7 +1095,7 @@ private void GammaColorTempSlider_ValueChanged(object sender, EventArgs e)
 
             UpdateGammaLabels();
             UpdateColorTempLabel();
-            _gammaCheckBox.Checked = true;
+            SyncSlidersToSelectedMonitor();
 
             string current = GetCurrentPresetName();
             _currentPresetName = current;
@@ -1332,6 +1333,9 @@ private void MonitorSelectorComboBox_SelectedIndexChanged(object sender, EventAr
         {
             if (_isUpdatingGammaSliders) return;
 
+            int prevIndex = _previousMonitorSelectedIndex;
+            _previousMonitorSelectedIndex = _monitorSelectorComboBox.SelectedIndex;
+
             if (IsGlobalMonitorSelected() && Settings.GammaPerDisplay.Count > 0)
             {
                 bool hasManual = Settings.GammaPerDisplay.Any(kvp => kvp.Value.Source == "manual");
@@ -1346,7 +1350,7 @@ private void MonitorSelectorComboBox_SelectedIndexChanged(object sender, EventAr
                     if (MessageBox.Show(msg, "同步确认", MessageBoxButtons.YesNo, MessageBoxIcon.Question) != DialogResult.Yes)
                     {
                         _isUpdatingGammaSliders = true;
-                        _monitorSelectorComboBox.SelectedIndex = 1;
+                        _monitorSelectorComboBox.SelectedIndex = prevIndex;
                         _isUpdatingGammaSliders = false;
                         return;
                     }
@@ -1506,8 +1510,11 @@ protected override void OnFormClosing(FormClosingEventArgs e)
                 _bgService.OnFormClosing(this);
                 e.Cancel = true;
                 Hide();
-                Dispose();
-                _bgService.EnterAppLightweightMode();
+                BeginInvoke(new Action(() =>
+                {
+                    _bgService.EnterAppLightweightMode();
+                    if (!IsDisposed) Dispose();
+                }));
                 return;
             }
             _formDisposed = true;

LumiShift/Form1.cs

@@ -714,7 +714,10 @@ public void EnterLightweightMode()
                 catch { }
             }
             _allControllers.Clear();
-            _monitors.Clear();
+            foreach (var monitor in _monitors)
+            {
+                monitor.Controller = null;
+            }
         }
 
         public void ExitLightweightMode()