diff --git a/src/InfiniFrame.Native/InfiniFrame.Native.proj b/src/InfiniFrame.Native/InfiniFrame.Native.proj
index dc3d1fa3..5d5b7fdf 100644
--- a/src/InfiniFrame.Native/InfiniFrame.Native.proj
+++ b/src/InfiniFrame.Native/InfiniFrame.Native.proj
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 
     <!-- Cross-platform Visual Studio placeholder for CMake -->
@@ -19,6 +19,10 @@
         <!-- Fallback -->
         <CMakeArch Condition="'$(CMakeArch)'==''">x64</CMakeArch>
 
+        <!-- macOS arch mapping -->
+        <CMakeOSXArch Condition="'$(CMakeArch)'=='x64'">x86_64</CMakeOSXArch>
+        <CMakeOSXArch Condition="'$(CMakeArch)'=='arm64'">arm64</CMakeOSXArch>
+
         <CMakeBuildDir>build/$(CMakeArch)/$(Configuration)</CMakeBuildDir>
         <CMakeOSDir Condition="'$(IsWindows)'=='true'">windows</CMakeOSDir>
         <CMakeOSDir Condition="'$(IsLinux)'=='true'">linux</CMakeOSDir>
@@ -53,11 +57,11 @@
         <Exec Condition="$(IsWindows)" Command="cmake --build $(CMakeBuildDir) --config $(Configuration) --parallel"/>
 
         <!-- Linux -->
-        <Exec Condition="$(IsLinux)" Command="cmake -B $(CMakeBuildDir) -S . -DCMAKE_OSX_ARCHITECTURES=$(CMakeArch)"/>
+        <Exec Condition="$(IsLinux)" Command="cmake -B $(CMakeBuildDir) -S ."/>
         <Exec Condition="$(IsLinux)" Command="cmake --build $(CMakeBuildDir) --config $(Configuration) --parallel"/>
 
         <!-- macOS -->
-        <Exec Condition="$(IsMac)" Command="cmake -B $(CMakeBuildDir) -S ."/>
+        <Exec Condition="$(IsMac)" Command="cmake -B $(CMakeBuildDir) -S . -DCMAKE_OSX_ARCHITECTURES=$(CMakeOSXArch)"/>
         <Exec Condition="$(IsMac)" Command="cmake --build $(CMakeBuildDir) --config $(Configuration) --parallel"/>
 
         <!-- Copy native binaries -->
diff --git a/src/InfiniFrame.Native/Platform/Linux/Window.cpp b/src/InfiniFrame.Native/Platform/Linux/Window.cpp
index 71e0ff5e..c1932413 100644
--- a/src/InfiniFrame.Native/Platform/Linux/Window.cpp
+++ b/src/InfiniFrame.Native/Platform/Linux/Window.cpp
@@ -537,7 +537,7 @@ void InfiniFrameWindow::GetGrantBrowserPermissions(bool* grant) const {
 }
 
 AutoString InfiniFrameWindow::GetUserAgent() const {
-    return const_cast<AutoString>(m_impl->_userAgent.c_str());
+    return AllocateStringCopy(m_impl->_userAgent);
 }
 
 void InfiniFrameWindow::GetMediaAutoplayEnabled(bool* enabled) const {
@@ -616,7 +616,8 @@ void InfiniFrameWindow::GetMinSize(int* width, int* height) const {
 }
 
 AutoString InfiniFrameWindow::GetTitle() const {
-    return const_cast<AutoString>(gtk_window_get_title(GTK_WINDOW(m_impl->_window)));
+    const char* title = gtk_window_get_title(GTK_WINDOW(m_impl->_window));
+    return g_strdup(title ? title : "");
 }
 
 void InfiniFrameWindow::GetTopmost(bool* topmost) const {
@@ -636,7 +637,7 @@ void InfiniFrameWindow::GetFocused(bool* isFocused) const {
 }
 
 AutoString InfiniFrameWindow::GetIconFileName() const {
-    return const_cast<AutoString>(m_impl->_iconFileName.c_str());
+    return AllocateStringCopy(m_impl->_iconFileName);
 }
 
 // ---------------------------------------------------------------------------------------------------------------------
diff --git a/src/InfiniFrame.Native/Platform/Mac/Window.mm b/src/InfiniFrame.Native/Platform/Mac/Window.mm
index bbb1a452..f07f3ecd 100644
--- a/src/InfiniFrame.Native/Platform/Mac/Window.mm
+++ b/src/InfiniFrame.Native/Platform/Mac/Window.mm
@@ -431,7 +431,7 @@
 
 AutoString InfiniFrameWindow::GetUserAgent() const
 {
-    return const_cast<AutoString>(m_impl->_userAgent.c_str());
+    return AllocateStringCopy(m_impl->_userAgent);
 }
 
 void InfiniFrameWindow::GetMediaAutoplayEnabled(bool* enabled) const
@@ -549,7 +549,7 @@
 
 AutoString InfiniFrameWindow::GetTitle() const
 {
-    return const_cast<AutoString>(m_impl->_windowTitle.c_str());
+    return AllocateStringCopy(m_impl->_windowTitle);
 }
 
 void InfiniFrameWindow::GetTopmost(bool* topmost) const
@@ -566,7 +566,7 @@
 
 AutoString InfiniFrameWindow::GetIconFileName() const
 {
-    return const_cast<AutoString>(m_impl->_iconFileName.c_str());
+    return AllocateStringCopy(m_impl->_iconFileName);
 }
 
 // ---------------------------------------------------------------------------------------------------------------------
diff --git a/src/InfiniFrame.Native/Platform/Windows/DarkMode.cpp b/src/InfiniFrame.Native/Platform/Windows/DarkMode.cpp
index 2a26764b..0dc18ec5 100644
--- a/src/InfiniFrame.Native/Platform/Windows/DarkMode.cpp
+++ b/src/InfiniFrame.Native/Platform/Windows/DarkMode.cpp
@@ -198,10 +198,14 @@ bool IsColorSchemeChange(const LPARAM l_param) noexcept {
         -1,
         TRUE
         ) == CSTR_EQUAL) {
-        RefreshImmersiveColorPolicyState();
+        if (RefreshImmersiveColorPolicyState != nullptr) {
+            RefreshImmersiveColorPolicyState();
+        }
         return_value = true;
     }
 
-    GetIsImmersiveColorUsingHighContrast(IHCM_REFRESH);
+    if (GetIsImmersiveColorUsingHighContrast != nullptr) {
+        GetIsImmersiveColorUsingHighContrast(IHCM_REFRESH);
+    }
     return return_value;
 }
diff --git a/src/InfiniFrame.Native/Platform/Windows/Window.cpp b/src/InfiniFrame.Native/Platform/Windows/Window.cpp
index 62b351d2..0d13c05c 100644
--- a/src/InfiniFrame.Native/Platform/Windows/Window.cpp
+++ b/src/InfiniFrame.Native/Platform/Windows/Window.cpp
@@ -453,14 +453,16 @@ LRESULT CALLBACK WindowProc(const HWND hwnd, const UINT uMsg, const WPARAM wPara
         }
         case WM_ACTIVATE: {
             InfiniFrameWindow * instance = hwndToInfiniFrame[hwnd];
-            if (LOWORD(wParam) == WA_INACTIVE) {
-                instance->InvokeFocusOut();
-            }
-            else {
-                instance->FocusWebView2();
-                instance->InvokeFocusIn();
+            if (instance) {
+                if (LOWORD(wParam) == WA_INACTIVE) {
+                    instance->InvokeFocusOut();
+                }
+                else {
+                    instance->FocusWebView2();
+                    instance->InvokeFocusIn();
 
-                return 0;
+                    return 0;
+                }
             }
             break;
         }
@@ -610,8 +612,11 @@ void InfiniFrameWindow::GetContextMenuEnabled(bool* enabled) const {
         return;
     }
     wil::com_ptr<ICoreWebView2Settings> settings;
-    if (SUCCEEDED(m_impl->_webviewWindow->get_Settings(&settings)) && settings)
-        settings->get_AreDefaultContextMenusEnabled(reinterpret_cast<BOOL*>(enabled));
+    if (SUCCEEDED(m_impl->_webviewWindow->get_Settings(&settings)) && settings) {
+        BOOL boolValue = FALSE;
+        settings->get_AreDefaultContextMenusEnabled(&boolValue);
+        *enabled = (boolValue != FALSE);
+    }
 }
 
 void InfiniFrameWindow::GetZoomEnabled(bool* enabled) const {
@@ -620,8 +625,11 @@ void InfiniFrameWindow::GetZoomEnabled(bool* enabled) const {
         return;
     }
     wil::com_ptr<ICoreWebView2Settings> settings;
-    if (SUCCEEDED(m_impl->_webviewWindow->get_Settings(&settings)) && settings)
-        settings->get_IsZoomControlEnabled(reinterpret_cast<BOOL*>(enabled));
+    if (SUCCEEDED(m_impl->_webviewWindow->get_Settings(&settings)) && settings) {
+        BOOL boolValue = FALSE;
+        settings->get_IsZoomControlEnabled(&boolValue);
+        *enabled = (boolValue != FALSE);
+    }
 }
 
 void InfiniFrameWindow::GetDevToolsEnabled(bool* enabled) const {
@@ -630,8 +638,11 @@ void InfiniFrameWindow::GetDevToolsEnabled(bool* enabled) const {
         return;
     }
     wil::com_ptr<ICoreWebView2Settings> settings;
-    if (SUCCEEDED(m_impl->_webviewWindow->get_Settings(&settings)) && settings)
-        settings->get_AreDevToolsEnabled(reinterpret_cast<BOOL*>(enabled));
+    if (SUCCEEDED(m_impl->_webviewWindow->get_Settings(&settings)) && settings) {
+        BOOL boolValue = FALSE;
+        settings->get_AreDevToolsEnabled(&boolValue);
+        *enabled = (boolValue != FALSE);
+    }
 }
 
 void InfiniFrameWindow::GetFullScreen(bool* fullScreen) const {
@@ -644,7 +655,7 @@ void InfiniFrameWindow::GetGrantBrowserPermissions(bool* grant) const {
 }
 
 AutoString InfiniFrameWindow::GetUserAgent() const {
-    return const_cast<AutoString>(m_impl->_userAgent.c_str());
+    return AllocateStringCopy(m_impl->_userAgent);
 }
 
 void InfiniFrameWindow::GetMediaAutoplayEnabled(bool* enabled) const {
@@ -684,7 +695,7 @@ void InfiniFrameWindow::GetNotificationsEnabled(bool* enabled) const {
 }
 
 AutoString InfiniFrameWindow::GetIconFileName() const {
-    return const_cast<AutoString>(m_impl->_iconFileName.c_str());
+    return AllocateStringCopy(m_impl->_iconFileName);
 }
 
 void InfiniFrameWindow::GetMaximized(bool* isMaximized) const {
@@ -739,7 +750,7 @@ void InfiniFrameWindow::GetMinSize(int* width, int* height) const {
 }
 
 AutoString InfiniFrameWindow::GetTitle() const {
-    return const_cast<AutoString>(m_impl->_windowTitle.c_str());
+    return AllocateStringCopy(m_impl->_windowTitle);
 }
 
 void InfiniFrameWindow::GetTopmost(bool* topmost) const {
diff --git a/src/InfiniFrame.Native/Utils/Common.h b/src/InfiniFrame.Native/Utils/Common.h
index 54987d9c..f01864e5 100644
--- a/src/InfiniFrame.Native/Utils/Common.h
+++ b/src/InfiniFrame.Native/Utils/Common.h
@@ -15,6 +15,7 @@
 #include <optional>
 #include <algorithm>
 #include <system_error>
+#include <cstring>
 
 #ifdef _WIN32
 #include <windows.h>
@@ -152,4 +153,34 @@ template <typename T>
     return std::clamp(value, minVal, maxVal);
 }
 
+#ifdef _WIN32
+inline wchar_t* AllocateStringCopy(const std::wstring& str) {
+    const size_t len = str.length();
+    wchar_t* copy = new wchar_t[len + 1];
+    std::memcpy(copy, str.c_str(), (len + 1) * sizeof(wchar_t));
+    return copy;
+}
+
+#elif __linux__
+inline char* AllocateStringCopy(const std::string& str) {
+    return g_strdup(str.c_str());
+}
+
+#elif __APPLE__
+inline char* AllocateStringCopy(const std::string& str) {
+    const size_t len = str.length();
+    char* copy = static_cast<char*>(malloc(len + 1));
+    std::memcpy(copy, str.c_str(), len + 1);
+    return copy;
+}
+
+#else
+inline char* AllocateStringCopy(const std::string& str) {
+    const size_t len = str.length();
+    char* copy = static_cast<char*>(malloc(len + 1));
+    std::memcpy(copy, str.c_str(), len + 1);
+    return copy;
+}
+#endif
+
 #endif // INFINIFRAME_COMMON_H
diff --git a/src/InfiniFrame.Native/Utils/Event.h b/src/InfiniFrame.Native/Utils/Event.h
index bf6f23d5..3fb427af 100644
--- a/src/InfiniFrame.Native/Utils/Event.h
+++ b/src/InfiniFrame.Native/Utils/Event.h
@@ -85,7 +85,7 @@ class Event {
     private:
         mutable std::shared_mutex m_mutex;
         std::map<Token, Handler> m_handlers;
-        Token m_nextToken = 0;
+        Token m_nextToken = 1;
 };
 
 // ---------------------------------------------------------------------------------------------------------------------
diff --git a/src/InfiniFrame/InfiniFrameWindow.cs b/src/InfiniFrame/InfiniFrameWindow.cs
index e7783613..acdafeed 100644
--- a/src/InfiniFrame/InfiniFrameWindow.cs
+++ b/src/InfiniFrame/InfiniFrameWindow.cs
@@ -449,7 +449,13 @@ public void Close() {
         if (InstanceHandle == IntPtr.Zero) return;
 
         Interlocked.Exchange(ref _shutdownRequested, 1);
-        Invoke(() => InfiniFrameNative.Close(InstanceHandle));
+        Invoke(() => {
+            if (InstanceHandle == IntPtr.Zero) {
+                Logger.LogDebug("Window already closed");
+                return;
+            }
+            InfiniFrameNative.Close(InstanceHandle);
+        });
     }
 
     /// <summary>
@@ -471,7 +477,13 @@ public void SendWebMessage(string message) {
         }
 
         Logger.LogDebug(".SendWebMessage({Message})", message);
-        Invoke(() => InfiniFrameNative.SendWebMessage(InstanceHandle, message));
+        Invoke(() => {
+            if (Volatile.Read(ref _shutdownStarted) != 0 || InstanceHandle == IntPtr.Zero) {
+                Logger.LogDebug("Window closed before SendWebMessage could execute");
+                return;
+            }
+            InfiniFrameNative.SendWebMessage(InstanceHandle, message);
+        });
     }
 
     public Task SendWebMessageAsync(string message, CancellationToken ct = default) {
@@ -503,8 +515,19 @@ internal byte OnWindowClosing() {
     /// <param name="title">The title of the notification</param>
     /// <param name="body">The text of the notification</param>
     public void SendNotification(string title, string body) {
+        if (Volatile.Read(ref _shutdownStarted) != 0 || InstanceHandle == IntPtr.Zero) {
+            Logger.LogDebug("Skipping SendNotification during shutdown");
+            return;
+        }
+
         Logger.LogDebug(".SendNotification({Title}, {Body})", title, body);
-        Invoke(() => InfiniFrameNative.ShowNotification(InstanceHandle, title, body));
+        Invoke(() => {
+            if (Volatile.Read(ref _shutdownStarted) != 0 || InstanceHandle == IntPtr.Zero) {
+                Logger.LogDebug("Window closed before SendNotification could execute");
+                return;
+            }
+            InfiniFrameNative.ShowNotification(InstanceHandle, title, body);
+        });
     }
 
     /// <summary>
@@ -712,8 +735,12 @@ out string? resolvedIconFilePath
                 Invoke(InfiniFrameNative.RegisterMac);
 
             Invoke(() => InstanceHandle = InfiniFrameNative.Constructor(in StartupParameters));
+            
+            FreeCustomSchemeNames();
         }
         catch (Exception ex) when (IsNonFatalException(ex)) {
+            FreeCustomSchemeNames();
+            
             int lastError = 0;
             if (OperatingSystem.IsWindows())
                 lastError = Marshal.GetLastWin32Error();
@@ -726,7 +753,24 @@ out string? resolvedIconFilePath
     }
 
     /// <summary>
-    ///     Show a native open dialog.
+    ///     Frees unmanaged memory allocated for custom scheme names
+    /// </summary>
+    /// <remarks>
+    ///     This method should be called after the native constructor has copied the scheme names.
+    ///     The native side makes its own copies, so the managed side can safely free the memory
+    /// </remarks>
+    private void FreeCustomSchemeNames() {
+        if (StartupParameters.CustomSchemeNames == null) return;
+        
+        foreach (IntPtr ptr in StartupParameters.CustomSchemeNames) {
+            if (ptr != IntPtr.Zero) {
+                Marshal.FreeHGlobal(ptr);
+            }
+        }
+    }
+
+    /// <summary>
+    ///     Show a native open dialog
     /// </summary>
     /// <param name="foldersOnly">Whether files are hidden</param>
     /// <param name="title">Title of the dialog</param>