feat: add Windows title bar theme synchronization

lib/app_widget.dart

@@ -14,6 +14,7 @@ import 'package:kazumi/bean/dialog/dialog_helper.dart';
 import 'package:kazumi/bean/settings/theme_provider.dart';
 import 'package:provider/provider.dart';
 import 'package:kazumi/utils/constants.dart';
+import 'package:flutter/services.dart';
 
 class AppWidget extends StatefulWidget {
   const AppWidget({super.key});
@@ -36,6 +37,15 @@ class _AppWidgetState extends State<AppWidget>
     setPreventClose();
     WidgetsBinding.instance.addObserver(this);
     super.initState();
+
+    // Sync Windows title bar theme on startup and when theme changes
+    if (Platform.isWindows) {
+      final themeProvider = Provider.of<ThemeProvider>(context, listen: false);
+      _syncTitleBarTheme(themeProvider);
+      themeProvider.addListener(() {
+        if (mounted) _syncTitleBarTheme(themeProvider);
+      });
+    }
   }
 
   void setPreventClose() async {
@@ -167,15 +177,24 @@ class _AppWidgetState extends State<AppWidget>
   @override
   Future<void> didChangePlatformBrightness() async {
     super.didChangePlatformBrightness();
-    final ThemeProvider themeProvider = Provider.of<ThemeProvider>(context, listen: false);
-    KazumiLogger().i("Platform brightness changed, themeMode: ${themeProvider.themeMode}");
+    if (Platform.isWindows) {
+      final themeProvider = Provider.of<ThemeProvider>(context, listen: false);
+      _syncTitleBarTheme(themeProvider);
+    }
+  }
 
-    // Only update title bar theme when following system
-    // If user has forced a specific theme, keep title bar consistent with app content
-    if (themeProvider.themeMode == ThemeMode.system && Platform.isWindows) {
-      final brightness = WidgetsBinding.instance.platformDispatcher.platformBrightness;
-      KazumiLogger().i("Updating title bar brightness: $brightness");
-      await windowManager.setBrightness(brightness);
+  /// Sync Windows title bar theme with app theme using native DwmSetWindowAttribute.
+  /// This bypasses the window_manager plugin's registry check to force dark/light
+  /// title bar regardless of system-wide theme setting.
+  Future<void> _syncTitleBarTheme(ThemeProvider themeProvider) async {
+    final bool isDark = themeProvider.isEffectiveDark();
+    try {
+      await const MethodChannel('com.predidit.kazumi/titlebar')
+          .invokeMethod('setImmersiveDarkMode', {'enable': isDark});
+    } catch (_) {
+      // Fallback to window_manager plugin if native channel fails
+      await windowManager.setBrightness(
+          isDark ? Brightness.dark : Brightness.light);
     }
   }
 
@@ -231,9 +250,9 @@ class _AppWidgetState extends State<AppWidget>
       themeProvider.setThemeMode(ThemeMode.system, notify: false);
     }
 
-    // Set Windows title bar theme based on app theme
+    // Sync Windows title bar theme after theme mode is set
     if (Platform.isWindows) {
-      windowManager.setBrightness(themeProvider.isEffectiveDark() ? Brightness.dark : Brightness.light);
+      _syncTitleBarTheme(themeProvider);
     }
 
     themeProvider.setFontFamily(useSystemFont, notify: false);

lib/pages/settings/theme_settings_page.dart

@@ -13,7 +13,6 @@ import 'package:kazumi/bean/settings/color_type.dart';
 import 'package:kazumi/utils/utils.dart';
 import 'package:card_settings_ui/card_settings_ui.dart';
 import 'package:provider/provider.dart';
-import 'package:window_manager/window_manager.dart';
 
 class ThemeSettingsPage extends StatefulWidget {
   const ThemeSettingsPage({super.key});
@@ -123,11 +122,6 @@ class _ThemeSettingsPageState extends State<ThemeSettingsPage> {
     setState(() {
       defaultThemeMode = theme;
     });
-
-    // Update Windows title bar theme
-    if (Platform.isWindows) {
-      await windowManager.setBrightness(themeProvider.isEffectiveDark() ? Brightness.dark : Brightness.light);
-    }
   }
 
   void updateOledEnhance() {

windows/runner/flutter_window.cpp

@@ -8,6 +8,11 @@
 #include <flutter/standard_method_codec.h>
 #include <flutter/plugin_registrar_windows.h>
 #include <windows.h>
+#include <dwmapi.h>
+
+#ifndef DWMWA_USE_IMMERSIVE_DARK_MODE
+#define DWMWA_USE_IMMERSIVE_DARK_MODE 20
+#endif
 
 #include "flutter/generated_plugin_registrant.h"
 
@@ -54,6 +59,9 @@ bool FlutterWindow::OnCreate() {
   // Register Shortcut MethodChannel
   RegisterShortcutChannel();
 
+  // Register TitleBar Theme MethodChannel
+  RegisterTitleBarThemeChannel();
+
   return true;
 }
 
@@ -176,3 +184,29 @@ void FlutterWindow::RegisterShortcutChannel() {
     }
   });
 }
+
+// TitleBar Theme MethodChannel setup
+void FlutterWindow::RegisterTitleBarThemeChannel() {
+  auto channel = std::make_unique<flutter::MethodChannel<flutter::EncodableValue>>(
+      flutter_controller_->engine()->messenger(), "com.predidit.kazumi/titlebar",
+      &flutter::StandardMethodCodec::GetInstance());
+
+  channel->SetMethodCallHandler([this](const auto& call, auto result) {
+    if (call.method_name() == "setImmersiveDarkMode") {
+      const auto* arguments = std::get_if<flutter::EncodableMap>(call.arguments());
+      if (arguments) {
+        auto it = arguments->find(flutter::EncodableValue("enable"));
+        if (it != arguments->end()) {
+          BOOL dark_mode = std::get<bool>(it->second) ? TRUE : FALSE;
+          DwmSetWindowAttribute(GetHandle(), DWMWA_USE_IMMERSIVE_DARK_MODE,
+                                &dark_mode, sizeof(dark_mode));
+          result->Success();
+          return;
+        }
+      }
+      result->Error("InvalidArguments", "Missing 'enable' argument");
+    } else {
+      result->NotImplemented();
+    }
+  });
+}

windows/runner/flutter_window.h

@@ -37,6 +37,9 @@ class FlutterWindow : public Win32Window {
 
   // Register Shortcut MethodChannel
   void RegisterShortcutChannel();
+
+  // Register TitleBar Theme MethodChannel
+  void RegisterTitleBarThemeChannel();
 };
 
 #endif  // RUNNER_FLUTTER_WINDOW_H_