diff --git a/MVVM/Main.ps1 b/MVVM/Main.ps1
new file mode 100644
index 0000000..aae76a7
--- /dev/null
+++ b/MVVM/Main.ps1
@@ -0,0 +1,77 @@
+#Requires -Version 5.1
+Set-StrictMode -Version Latest
+
+Add-Type -AssemblyName PresentationFramework
+Add-Type -AssemblyName PresentationCore
+Add-Type -AssemblyName WindowsBase
+Add-Type -AssemblyName Microsoft.Win32
+
+$root = $PSScriptRoot
+
+# ---- Laden in Reihenfolge: Base -> Models -> Services -> ViewModels ----
+. "$root\ViewModels\BaseViewModel.ps1"   # Add-Type fuer ObservableBase + RelayCommand
+. "$root\Models\AddonModel.ps1"
+. "$root\Models\PolicyCheckModel.ps1"
+. "$root\Services\FirefoxService.ps1"
+. "$root\Services\RegistryService.ps1"
+. "$root\Services\PolicyService.ps1"
+. "$root\ViewModels\DeployViewModel.ps1"
+. "$root\ViewModels\DiagnosticViewModel.ps1"
+. "$root\ViewModels\MainViewModel.ps1"
+
+# ---- XAML laden ----
+[xml]$xaml = Get-Content "$root\Views\MainWindow.xaml"
+
+# x:Class entfernen (nicht benoetigt in PowerShell)
+$xaml.Window.RemoveAttribute("x:Class")
+
+$reader = [System.Xml.XmlNodeReader]::new($xaml)
+$window = [System.Windows.Markup.XamlReader]::Load($reader)
+
+# ---- ViewModel binden ----
+$vm = [MainViewModel]::new()
+$window.DataContext = $vm
+
+# ---- Code-Behind fuer einfache Hilfsfunktionen ----
+$addonGrid = $window.FindName("AddonGrid")
+
+$window.Add_SelectAll_Click = {
+    foreach ($a in $vm.Deploy.Addons) { $a.IsSelected = $true }
+}
+$window.Add_SelectNone_Click = {
+    foreach ($a in $vm.Deploy.Addons) { $a.IsSelected = $false }
+}
+
+# Click-Handler fuer Buttons die keinen Command haben (SelectAll/None)
+$window.FindName("AddonGrid") | Out-Null
+$window | Add-Member -MemberType ScriptMethod -Name "SelectAll_Click" -Force -Value {
+    foreach ($a in $vm.Deploy.Addons) { $a.IsSelected = $true }
+}
+$window | Add-Member -MemberType ScriptMethod -Name "SelectNone_Click" -Force -Value {
+    foreach ($a in $vm.Deploy.Addons) { $a.IsSelected = $false }
+}
+
+# Button-Referenzen fuer SelectAll/None direkt verdrahten
+$window.AddHandler(
+    [System.Windows.Controls.Button]::ClickEvent,
+    [System.Windows.RoutedEventHandler]{
+        param($sender, $e)
+        switch ($sender.Content) {
+            "Alle auswaehlen" { foreach ($a in $vm.Deploy.Addons) { $a.IsSelected = $true } }
+            "Keine"           { foreach ($a in $vm.Deploy.Addons) { $a.IsSelected = $false } }
+        }
+    }
+)
+
+# ---- Diagnose beim Tab-Wechsel automatisch ausfuehren ----
+$tabControl = $window.Content.Children | Where-Object { $_ -is [System.Windows.Controls.TabControl] }
+if ($tabControl) {
+    $tabControl.Add_SelectionChanged({
+        if ($tabControl.SelectedIndex -eq 1) {
+            $vm.Diagnostic.RunCheckCommand.Execute($null)
+        }
+    })
+}
+
+# ---- Fenster anzeigen ----
+$window.ShowDialog() | Out-Null