feat: Formulare-Menü mit Elternbrief-Einstieg + Arbeitsblatt-Personalisierung (Nutzer-Feedback)

Neue Menü-Kategorie "Formulare" in der Menüleiste: "Elternbrief erzeugen..." öffnet
jetzt einen Schüler-Picker statt nur aus der Schülerdetailansicht erreichbar zu sein,
"Arbeitsblatt personalisieren..." ist aktiv, sobald eine einzelne Lerngruppe geöffnet
ist, und erzeugt aus einer in TemplateDesigner gebauten .lavorlage-Vorlage ein PDF je
aktivem Gruppenmitglied - über eine von den Elternbrief-Vorlagen getrennte
WorksheetTemplateStore-Bibliothek.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

LehrerApp.Desktop/AppBootstrapper.cs

@@ -123,6 +123,7 @@ public static class AppBootstrapper
         services.AddSingleton<ITemplateLoader, TemplateLoader>();
         services.AddSingleton<ITemplateRenderer, QuestTemplateRenderer>();
         services.AddSingleton(_ => new TemplateStore(appData));
+        services.AddSingleton(_ => new WorksheetTemplateStore(new TemplateStore(appData, subfolder: "worksheet-template-packages")));
 
         // ── Datensicherheit (13.3) ───────────────────────────────────────────
         // Backup läuft vor dem Öffnen der Datenbank, rein dateibasiert (unabhängig von

LehrerApp.Desktop/Services/LetterDialogs.cs

@@ -0,0 +1,28 @@
+using Avalonia.Controls;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Desktop.ViewModels.Students;
+using LehrerApp.Desktop.Views.Students;
+using LehrerApp.Templating;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LehrerApp.Desktop.Services;
+
+/// <summary>Öffnet den bestehenden Elternbrief-Dialog für einen Schüler, egal ob der Aufruf aus
+/// der Schülerdetailansicht (Student schon im DataContext) oder aus dem Formulare-Menü (Student
+/// erst per Picker gewählt) kommt.</summary>
+public static class LetterDialogs
+{
+    public static async Task ShowCreateLetterDialogAsync(Window owner, Student student)
+    {
+        var vm = new CreateLetterDialogViewModel(student,
+            App.Services.GetRequiredService<TemplateStore>(),
+            App.Services.GetRequiredService<ITemplateRenderer>(),
+            App.Services.GetRequiredService<IGroupMembershipRepository>(),
+            App.Services.GetRequiredService<IGroupRepository>());
+        var dialog = new CreateLetterDialog { DataContext = vm };
+        var path = await dialog.ShowDialog<string?>(owner);
+        if (!string.IsNullOrEmpty(path) && File.Exists(path))
+            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(path) { UseShellExecute = true });
+    }
+}

LehrerApp.Desktop/ViewModels/Groups/PersonalizeWorksheetDialogViewModel.cs

@@ -0,0 +1,86 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Desktop.Services;
+using LehrerApp.Desktop.ViewModels.Students;
+using LehrerApp.Templating;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels.Groups;
+
+/// <summary>Erzeugt aus einer in TemplateDesigner gebauten Arbeitsblatt-.lavorlage-Vorlage ein
+/// personalisiertes PDF je aktivem Mitglied der aktuell geöffneten Lerngruppe. Nutzt bewusst
+/// dieselbe Platzhalter-/Rendering-Infrastruktur wie der Elternbrief-Dialog
+/// (<see cref="LetterPlaceholderBuilder"/>, <see cref="ITemplateRenderer"/>), aber eine getrennte
+/// <see cref="WorksheetTemplateStore"/>-Vorlagenbibliothek.</summary>
+public partial class PersonalizeWorksheetDialogViewModel : ObservableObject
+{
+    private readonly LearningGroup _group;
+    private readonly WorksheetTemplateStore _templates;
+    private readonly ITemplateRenderer _renderer;
+
+    [ObservableProperty] private LetterTemplateChoice? _selectedTemplate;
+    [ObservableProperty] private string _statusMessage = "";
+
+    public string GroupName => $"{_group.Name} · {_group.SchoolYear}";
+    public ObservableCollection<LetterTemplateChoice> Templates { get; } = [];
+    public ObservableCollection<WorksheetStudentChoice> Students { get; } = [];
+    public ObservableCollection<WorksheetGenerationResult> Results { get; } = [];
+    public bool HasNoTemplates => Templates.Count == 0;
+    public bool HasResults => Results.Count > 0;
+
+    public PersonalizeWorksheetDialogViewModel(LearningGroup group, IReadOnlyList<Guid> studentIds,
+        IStudentRepository students, WorksheetTemplateStore templates, ITemplateRenderer renderer)
+    {
+        _group = group; _templates = templates; _renderer = renderer;
+        foreach (var template in templates.Store.GetTemplates()) Templates.Add(new(template));
+        SelectedTemplate = Templates.FirstOrDefault();
+        foreach (var id in studentIds)
+            if (students.GetById(id) is { } student) Students.Add(new(student));
+    }
+
+    public void Generate(string outputFolder)
+    {
+        Results.Clear();
+        if (SelectedTemplate is null) return;
+        LoadedTemplate loaded;
+        try { loaded = _templates.Store.Load(SelectedTemplate.Model); }
+        catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException)
+        { StatusMessage = $"Vorlage ist ungültig: {ex.Message}"; return; }
+
+        Directory.CreateDirectory(outputFolder);
+        foreach (var choice in Students.Where(x => x.IsIncluded))
+        {
+            var student = choice.Model;
+            try
+            {
+                var values = LetterPlaceholderBuilder.BuildStandardValues(student, contact: null, _group,
+                    DateOnly.FromDateTime(DateTime.Now), "", "");
+                var pdf = _renderer.RenderToPdf(loaded, new LetterDataProvider(values));
+                var fileName = SanitizeFileName($"{SelectedTemplate.Name}_{student.LastName}_{student.FirstName}.pdf");
+                File.WriteAllBytes(Path.Combine(outputFolder, fileName), pdf);
+                Results.Add(new(student.FullName, true, ""));
+            }
+            catch (Exception ex) when (ex is IOException or InvalidDataException or UnauthorizedAccessException or TemplateValidationException)
+            { Results.Add(new(student.FullName, false, ex.Message)); }
+        }
+        OnPropertyChanged(nameof(HasResults));
+        StatusMessage = $"{Results.Count(x => x.Success)} von {Results.Count} Arbeitsblättern erzeugt.";
+    }
+
+    private static string SanitizeFileName(string value)
+    { foreach (var character in Path.GetInvalidFileNameChars()) value = value.Replace(character, '_'); return value; }
+}
+
+public partial class WorksheetStudentChoice(Student model) : ObservableObject
+{
+    public Student Model { get; } = model;
+    public string FullName => Model.FullName;
+    [ObservableProperty] private bool _isIncluded = true;
+}
+
+public sealed record WorksheetGenerationResult(string StudentName, bool Success, string ErrorMessage)
+{
+    public string Icon => Success ? "✓" : "⚠";
+    public string Color => Success ? "SeaGreen" : "#D97706";
+}

LehrerApp.Desktop/ViewModels/MainWindowViewModel.cs

@@ -12,6 +12,7 @@ using LehrerApp.Desktop.ViewModels.Students;
 using LehrerApp.Desktop.ViewModels.Workload;
 using Microsoft.Extensions.DependencyInjection;
 using System.Collections.ObjectModel;
+using System.ComponentModel;
 
 namespace LehrerApp.Desktop.ViewModels;
 
@@ -38,6 +39,9 @@ public partial class MainWindowViewModel : ObservableObject
     public bool IsClassTeacherActive => ActiveNavItem == NavItem.ClassTeacher;
     public bool IsSettingsActive  => ActiveNavItem == NavItem.Settings;
 
+    public GroupDetailViewModel? CurrentGroupDetail => CurrentPage as GroupDetailViewModel;
+    public bool CanPersonalizeWorksheet => CurrentGroupDetail?.Group is not null;
+
     public MainWindowViewModel(IServiceProvider services,
         DashboardViewModel dashboard, SchoolYearService sy,
         SyncStatusViewModel syncStatus, NotificationService notifications, AppLockViewModel appLock,
@@ -103,6 +107,25 @@ public partial class MainWindowViewModel : ObservableObject
         }
     }
 
+    // GroupDetailViewModel.Group wird erst nach dem Wechsel von CurrentPage per LoadGroup gesetzt
+    // (siehe Kommentar in NavigateToGroupDetail) - ohne dieses Abonnement bliebe
+    // CanPersonalizeWorksheet bis zum nächsten Seitenwechsel auf dem alten Stand.
+    private GroupDetailViewModel? _observedGroupDetail;
+
+    partial void OnCurrentPageChanged(ObservableObject? value)
+    {
+        if (_observedGroupDetail is not null) _observedGroupDetail.PropertyChanged -= OnGroupDetailPropertyChanged;
+        _observedGroupDetail = value as GroupDetailViewModel;
+        if (_observedGroupDetail is not null) _observedGroupDetail.PropertyChanged += OnGroupDetailPropertyChanged;
+        OnPropertyChanged(nameof(CurrentGroupDetail));
+        OnPropertyChanged(nameof(CanPersonalizeWorksheet));
+    }
+
+    private void OnGroupDetailPropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(GroupDetailViewModel.Group)) OnPropertyChanged(nameof(CanPersonalizeWorksheet));
+    }
+
     partial void OnActiveNavItemChanged(NavItem value)
     {
         OnPropertyChanged(nameof(IsDashboardActive));

LehrerApp.Desktop/ViewModels/Settings/SettingsViewModel.WorksheetTemplates.cs

@@ -0,0 +1,60 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Templating;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels.Settings;
+
+public partial class SettingsViewModel
+{
+    [ObservableProperty] private string _worksheetTemplateStatus = "";
+    public ObservableCollection<LetterTemplateListItem> WorksheetTemplateList { get; } = [];
+
+    private void LoadWorksheetTemplates()
+    {
+        WorksheetTemplateList.Clear();
+        foreach (var template in _worksheetTemplates.Store.GetTemplates()) WorksheetTemplateList.Add(CreateWorksheetItem(template));
+    }
+
+    public void ImportWorksheetTemplate(string path)
+    {
+        WorksheetTemplateStatus = "";
+        try
+        {
+            var template = _worksheetTemplates.Store.Import(path);
+            LoadWorksheetTemplates();
+            WorksheetTemplateStatus = $"„{template.Name}“ wurde geprüft und lokal importiert.";
+        }
+        catch (Exception ex) when (ex is IOException or InvalidDataException or UnauthorizedAccessException or TemplateValidationException)
+        { WorksheetTemplateStatus = $"Import fehlgeschlagen: {ex.Message}"; }
+    }
+
+    [RelayCommand]
+    private void ValidateWorksheetTemplate(LetterTemplateListItem? item)
+    {
+        if (item is null) return;
+        try
+        {
+            var refreshed = CreateWorksheetItem(item.Model);
+            var index = WorksheetTemplateList.IndexOf(item);
+            if (index >= 0) WorksheetTemplateList[index] = refreshed;
+            WorksheetTemplateStatus = $"„{item.Name}“ ist gültig (Schema {refreshed.SchemaVersion}).";
+        }
+        catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException)
+        { WorksheetTemplateStatus = $"„{item.Name}“ ist ungültig: {ex.Message}"; }
+    }
+
+    [RelayCommand]
+    private void DeleteWorksheetTemplate(LetterTemplateListItem? item)
+    {
+        if (item is null) return;
+        _worksheetTemplates.Store.Delete(item.Id); WorksheetTemplateList.Remove(item); WorksheetTemplateStatus = "Vorlage gelöscht.";
+    }
+
+    private LetterTemplateListItem CreateWorksheetItem(InstalledTemplate template)
+    {
+        var loaded = _worksheetTemplates.Store.Load(template);
+        return new(template, loaded.Manifest.SchemaVersion, loaded.Manifest.Placeholders.Count(x => !x.IsConstant),
+            loaded.Manifest.Placeholders.Count(x => !x.IsConstant && x.Required));
+    }
+}

LehrerApp.Desktop/ViewModels/Settings/SettingsViewModel.cs

@@ -62,6 +62,7 @@ public partial class SettingsViewModel : ObservableObject
     private readonly IStudentRepository _students;
     private readonly IShorthandCodeRepository _shorthandCodes;
     private readonly TemplateStore _letterTemplates;
+    private readonly WorksheetTemplateStore _worksheetTemplates;
 
     [ObservableProperty] private int _activeTabIndex;
 
@@ -102,6 +103,7 @@ public partial class SettingsViewModel : ObservableObject
         IShorthandCodeRepository shorthandCodes, ISchoolHolidayRepository schoolHolidays,
         SchoolCalendarSettingsService calendarSettings, PeriodScheduleService periodSchedule,
         ISupervisionDutyRepository supervisionDuties, TemplateStore letterTemplates,
+        WorksheetTemplateStore worksheetTemplates,
         AiSettingsService aiSettings, AiPlanningService aiPlanning, McpSettingsService mcpSettings,
         Services.Mcp.McpClientRegistrationService mcpRegistration,
         WebUntisSettingsService untisSettings,
@@ -139,6 +141,7 @@ public partial class SettingsViewModel : ObservableObject
         _periodSchedule = periodSchedule;
         _supervisionDuties = supervisionDuties;
         _letterTemplates = letterTemplates;
+        _worksheetTemplates = worksheetTemplates;
         _aiSettings = aiSettings;
         _aiPlanning = aiPlanning;
         _mcpSettings = mcpSettings;
@@ -169,6 +172,7 @@ public partial class SettingsViewModel : ObservableObject
         LoadPeriodTimes();
         LoadSupervisionDuties();
         LoadLetterTemplates();
+        LoadWorksheetTemplates();
         LoadAiSettings();
         LoadMcpSettings();
         LoadMcpRegistrationStatus();

LehrerApp.Desktop/ViewModels/Students/StudentPickerDialogViewModel.cs

@@ -0,0 +1,48 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Desktop.ViewModels.Groups;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels.Students;
+
+/// <summary>Einfacher "einen Schüler wählen"-Dialog für Einstiegspunkte ohne bereits geöffneten
+/// Schüler (z.B. das Formulare-Menü) - anders als <see cref="Groups.AddStudentToGroupDialogViewModel"/>
+/// ohne Gruppenbezug/Mitgliedschaftszeitraum, einfach alle Schüler durchsuchbar.</summary>
+public partial class StudentPickerDialogViewModel : ObservableObject
+{
+    private readonly IStudentRepository _students;
+
+    [ObservableProperty] private string _searchText = "";
+    [ObservableProperty] private StudentPickerItem? _selectedStudent;
+    [ObservableProperty] private string _validationMessage = "";
+
+    public ObservableCollection<StudentPickerItem> Students { get; } = [];
+    public Student? Result { get; private set; }
+
+    public StudentPickerDialogViewModel(IStudentRepository students)
+    {
+        _students = students;
+        LoadStudents();
+    }
+
+    partial void OnSearchTextChanged(string value) => LoadStudents();
+
+    private void LoadStudents()
+    {
+        var matches = _students.GetAll()
+            .Where(s => string.IsNullOrWhiteSpace(SearchText) ||
+                        s.FullName.Contains(SearchText, StringComparison.OrdinalIgnoreCase))
+            .OrderBy(s => s.FullName, StringComparer.CurrentCultureIgnoreCase);
+        Students.Clear();
+        foreach (var student in matches) Students.Add(new StudentPickerItem(student));
+    }
+
+    [RelayCommand]
+    private void Select()
+    {
+        if (SelectedStudent is null) { ValidationMessage = "Bitte einen Schüler auswählen."; return; }
+        Result = _students.GetById(SelectedStudent.Id);
+    }
+}

LehrerApp.Desktop/Views/Groups/PersonalizeWorksheetDialog.axaml

@@ -0,0 +1,62 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Groups"
+        x:Class="LehrerApp.Desktop.Views.Groups.PersonalizeWorksheetDialog"
+        x:DataType="vm:PersonalizeWorksheetDialogViewModel"
+        Title="Arbeitsblatt personalisieren"
+        Width="460" Height="620"
+        CanResize="False" WindowStartupLocation="CenterOwner">
+
+  <Grid RowDefinitions="Auto,Auto,*,Auto,Auto" Margin="24">
+
+    <StackPanel Grid.Row="0" Spacing="4" Margin="0,0,0,14">
+      <TextBlock Text="Arbeitsblatt personalisieren" Classes="dialogtitle"/>
+      <TextBlock Text="{Binding GroupName}" FontSize="12" Opacity="0.65"/>
+    </StackPanel>
+
+    <StackPanel Grid.Row="1" Spacing="10" Margin="0,0,0,14">
+      <TextBlock Text="Vorlage" FontSize="12" FontWeight="SemiBold" Opacity="0.7"/>
+      <ComboBox ItemsSource="{Binding Templates}" SelectedItem="{Binding SelectedTemplate}"
+                HorizontalAlignment="Stretch" DisplayMemberBinding="{Binding Name}"/>
+      <TextBlock Text="Noch keine Arbeitsblatt-Vorlage importiert — in den Einstellungen unter „Briefvorlagen“ eine .lavorlage-Datei aus dem Vorlagen-Designer hinzufügen."
+                 Classes="emptyhint" TextWrapping="Wrap"
+                 IsVisible="{Binding HasNoTemplates}"/>
+    </StackPanel>
+
+    <ScrollViewer Grid.Row="2">
+      <StackPanel Spacing="4">
+        <TextBlock Text="Für diese Schüler erzeugen" FontSize="12" FontWeight="SemiBold" Opacity="0.7" Margin="0,0,0,4"/>
+        <ItemsControl ItemsSource="{Binding Students}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:WorksheetStudentChoice">
+              <CheckBox Content="{Binding FullName}" IsChecked="{Binding IsIncluded}" Margin="0,3"/>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+
+        <ItemsControl ItemsSource="{Binding Results}" Margin="0,10,0,0" IsVisible="{Binding HasResults}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:WorksheetGenerationResult">
+              <Grid ColumnDefinitions="20,*" Margin="0,2">
+                <TextBlock Grid.Column="0" Text="{Binding Icon}" Foreground="{Binding Color}"/>
+                <TextBlock Grid.Column="1" FontSize="12">
+                  <Run Text="{Binding StudentName}"/><Run Text=" "/><Run Text="{Binding ErrorMessage}" Foreground="#D97706"/>
+                </TextBlock>
+              </Grid>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+      </StackPanel>
+    </ScrollViewer>
+
+    <TextBlock Grid.Row="3" Text="{Binding StatusMessage}" FontSize="12" Margin="0,10,0,0" TextWrapping="Wrap"
+               IsVisible="{Binding StatusMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+    <Grid Grid.Row="4" ColumnDefinitions="*,8,*" Margin="0,16,0,0">
+      <Button Grid.Column="0" Content="Schließen" HorizontalAlignment="Stretch" Click="OnClose"/>
+      <Button Grid.Column="2" Content="Erzeugen…" HorizontalAlignment="Stretch" Click="OnGenerate"
+              IsEnabled="{Binding !HasNoTemplates}"/>
+    </Grid>
+
+  </Grid>
+</Window>

LehrerApp.Desktop/Views/Groups/PersonalizeWorksheetDialog.axaml.cs

@@ -0,0 +1,25 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Platform.Storage;
+using LehrerApp.Desktop.ViewModels.Groups;
+
+namespace LehrerApp.Desktop.Views.Groups;
+
+public partial class PersonalizeWorksheetDialog : Window
+{
+    public PersonalizeWorksheetDialog() => InitializeComponent();
+
+    private async void OnGenerate(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is not PersonalizeWorksheetDialogViewModel vm) return;
+        var folders = await StorageProvider.OpenFolderPickerAsync(new FolderPickerOpenOptions
+        {
+            Title = "Zielordner für die personalisierten Arbeitsblätter wählen",
+            AllowMultiple = false,
+        });
+        if (folders.Count == 0) return;
+        vm.Generate(folders[0].Path.LocalPath);
+    }
+
+    private void OnClose(object? sender, RoutedEventArgs e) => Close();
+}

LehrerApp.Desktop/Views/MainWindow.axaml

@@ -40,6 +40,12 @@
         <MenuItem Header="Klassenbuchabgleich…" Click="OnCompareUntisKlassenbuch"/>
         <MenuItem Header="Hausaufgabenabgleich…" Click="OnCompareUntisHausaufgaben"/>
       </MenuItem>
+      <MenuItem Header="Formulare">
+        <MenuItem Header="Elternbrief erzeugen…" Click="OnCreateParentLetter"/>
+        <MenuItem Header="Arbeitsblatt personalisieren…" Click="OnPersonalizeWorksheet"
+                  IsEnabled="{Binding CanPersonalizeWorksheet}"
+                  ToolTip.Tip="Nur verfügbar, während eine einzelne Lerngruppe geöffnet ist"/>
+      </MenuItem>
     </Menu>
   <DrawerPage x:Name="RootDrawer"
               DrawerLength="220"

LehrerApp.Desktop/Views/MainWindow.axaml.cs

@@ -1,10 +1,17 @@
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Threading;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
 using LehrerApp.Desktop.Services;
 using LehrerApp.Desktop.ViewModels;
+using LehrerApp.Desktop.ViewModels.Groups;
+using LehrerApp.Desktop.ViewModels.Students;
+using LehrerApp.Desktop.Views.Groups;
+using LehrerApp.Desktop.Views.Students;
 using LehrerApp.Desktop.Views.UntisHub;
 using LehrerApp.Sync;
+using LehrerApp.Templating;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace LehrerApp.Desktop.Views;
@@ -45,6 +52,25 @@ public partial class MainWindow : Window
         await UntisHubActions.RunHausaufgabenAsync(this, App.Services.GetRequiredService<UntisHubService>());
     }
 
+    private async void OnCreateParentLetter(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
+    {
+        var picker = new StudentPickerDialog
+        { DataContext = new StudentPickerDialogViewModel(App.Services.GetRequiredService<IStudentRepository>()) };
+        if (await picker.ShowDialog<Student?>(this) is { } student)
+            await LetterDialogs.ShowCreateLetterDialogAsync(this, student);
+    }
+
+    private async void OnPersonalizeWorksheet(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
+    {
+        if (DataContext is not MainWindowViewModel { CurrentGroupDetail.Group: { } group } vm) return;
+        var studentIds = vm.CurrentGroupDetail!.Students.Select(s => s.Id).ToList();
+        var dialogVm = new PersonalizeWorksheetDialogViewModel(group, studentIds,
+            App.Services.GetRequiredService<IStudentRepository>(),
+            App.Services.GetRequiredService<WorksheetTemplateStore>(),
+            App.Services.GetRequiredService<ITemplateRenderer>());
+        await new PersonalizeWorksheetDialog { DataContext = dialogVm }.ShowDialog(this);
+    }
+
     private void OnWindowKeyDown(object? sender, KeyEventArgs e)
     {
         if (DataContext is not MainWindowViewModel vm) return;

LehrerApp.Desktop/Views/Settings/SettingsView.axaml

@@ -393,6 +393,66 @@
             <Separator/>
             <TextBlock Text="Vorlagen werden mit dem separaten LehrerApp Vorlagen-Designer erstellt. Designer und Hauptapp verwenden exakt dieselbe QuestPDF-Renderingbibliothek."
                        FontSize="12" Opacity="0.65" TextWrapping="Wrap"/>
+
+            <Separator Margin="0,8"/>
+            <TextBlock Text="Arbeitsblatt-Vorlagen" FontSize="15" FontWeight="SemiBold"/>
+            <TextBlock Text="Eigene Vorlagenbibliothek für „Arbeitsblatt personalisieren…“ im Formulare-Menü — getrennt von den Elternbrief-Vorlagen oben, damit sich beide Listen nicht vermischen."
+                       FontSize="12" Opacity="0.65" TextWrapping="Wrap"/>
+
+            <Grid ColumnDefinitions="Auto,*" ColumnSpacing="12">
+              <Button Grid.Column="0" Content="＋ .lavorlage importieren" Click="OnImportWorksheetTemplateClick"/>
+              <TextBlock Grid.Column="1" Text="{Binding WorksheetTemplateStatus}" FontSize="12"
+                         VerticalAlignment="Center" TextWrapping="Wrap"
+                         IsVisible="{Binding WorksheetTemplateStatus, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+            </Grid>
+
+            <TextBlock Text="Noch keine Arbeitsblatt-Vorlage importiert." Classes="emptyhint"
+                       IsVisible="{Binding !WorksheetTemplateList.Count}"/>
+
+            <ItemsControl ItemsSource="{Binding WorksheetTemplateList}">
+              <ItemsControl.ItemTemplate>
+                <DataTemplate DataType="vm:LetterTemplateListItem">
+                  <Border BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+                          BorderThickness="1" CornerRadius="7" Padding="14,12" Margin="0,0,0,9">
+                    <StackPanel Spacing="8">
+                      <Grid ColumnDefinitions="*,Auto,Auto,Auto">
+                        <StackPanel Grid.Column="0">
+                          <TextBlock Text="{Binding Name}" FontWeight="SemiBold" FontSize="14"/>
+                          <TextBlock FontSize="11" Opacity="0.55">
+                            <Run Text="{Binding PackageFileName}"/><Run Text=" · "/>
+                            <Run Text="{Binding ValidationSummary}"/>
+                          </TextBlock>
+                        </StackPanel>
+                        <Button Grid.Column="1" Content="Öffnen" FontSize="12" Padding="10,4"
+                                Margin="8,0,0,0" Tag="{Binding}" Click="OnOpenWorksheetTemplateClick"/>
+                        <Button Grid.Column="2" Content="Neu prüfen" FontSize="12" Padding="10,4"
+                                Margin="8,0,0,0"
+                                Command="{Binding $parent[ItemsControl].((vm:SettingsViewModel)DataContext).ValidateWorksheetTemplateCommand}"
+                                CommandParameter="{Binding}"/>
+                        <Button Grid.Column="3" Content="Löschen" FontSize="12" Padding="10,4"
+                                Margin="8,0,0,0"
+                                Command="{Binding $parent[ItemsControl].((vm:SettingsViewModel)DataContext).DeleteWorksheetTemplateCommand}"
+                                CommandParameter="{Binding}"/>
+                      </Grid>
+
+                      <ItemsControl ItemsSource="{Binding Issues}" IsVisible="{Binding HasIssues}">
+                        <ItemsControl.ItemTemplate>
+                          <DataTemplate DataType="vm:LetterTemplateIssueItem">
+                            <Grid ColumnDefinitions="24,*" Margin="0,2">
+                              <TextBlock Grid.Column="0" Text="{Binding Icon}" Foreground="{Binding Color}"/>
+                              <TextBlock Grid.Column="1" Text="{Binding Message}" Foreground="{Binding Color}"
+                                         FontSize="12" TextWrapping="Wrap"/>
+                            </Grid>
+                          </DataTemplate>
+                        </ItemsControl.ItemTemplate>
+                      </ItemsControl>
+                      <TextBlock Text="✓ Vorlage ohne Auffälligkeiten" Foreground="SeaGreen" FontSize="12"
+                                 IsVisible="{Binding HasNoIssues}"/>
+                    </StackPanel>
+                  </Border>
+                </DataTemplate>
+              </ItemsControl.ItemTemplate>
+            </ItemsControl>
           </StackPanel>
         </ScrollViewer>
       </ContentPage>

LehrerApp.Desktop/Views/Settings/SettingsView.axaml.cs

@@ -277,4 +277,26 @@ public partial class SettingsView : UserControl
         if (!File.Exists(path)) return;
         System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(path) { UseShellExecute = true });
     }
+
+    private async void OnImportWorksheetTemplateClick(object? sender, RoutedEventArgs e)
+    {
+        var topLevel = TopLevel.GetTopLevel(this);
+        if (topLevel is null || DataContext is not SettingsViewModel vm) return;
+
+        var files = await topLevel.StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions
+        {
+            Title = "LehrerApp-Arbeitsblattvorlage importieren",
+            AllowMultiple = false,
+            FileTypeFilter = [new FilePickerFileType("LehrerApp-Vorlagen") { Patterns = ["*.lavorlage"] }],
+        });
+        if (files.Count > 0) vm.ImportWorksheetTemplate(files[0].Path.LocalPath);
+    }
+
+    private void OnOpenWorksheetTemplateClick(object? sender, RoutedEventArgs e)
+    {
+        if (sender is not Button { Tag: LetterTemplateListItem item }) return;
+        var path = item.Model.PackagePath;
+        if (!File.Exists(path)) return;
+        System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(path) { UseShellExecute = true });
+    }
 }

LehrerApp.Desktop/Views/Students/StudentDetailView.axaml.cs

@@ -8,7 +8,6 @@ using LehrerApp.Desktop.Services;
 using LehrerApp.Desktop.ViewModels.Students;
 using LehrerApp.Desktop.Views.Shared;
 using Microsoft.Extensions.DependencyInjection;
-using LehrerApp.Templating;
 
 namespace LehrerApp.Desktop.Views.Students;
 
@@ -56,16 +55,7 @@ public partial class StudentDetailView : UserControl
     {
         var owner = TopLevel.GetTopLevel(this) as Window;
         if (owner is null || DataContext is not StudentDetailViewModel { Student: { } student }) return;
-
-        var vm = new CreateLetterDialogViewModel(student,
-            App.Services.GetRequiredService<TemplateStore>(),
-            App.Services.GetRequiredService<ITemplateRenderer>(),
-            App.Services.GetRequiredService<IGroupMembershipRepository>(),
-            App.Services.GetRequiredService<IGroupRepository>());
-        var dialog = new CreateLetterDialog { DataContext = vm };
-        var path = await dialog.ShowDialog<string?>(owner);
-        if (!string.IsNullOrEmpty(path) && File.Exists(path))
-            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(path) { UseShellExecute = true });
+        await LetterDialogs.ShowCreateLetterDialogAsync(owner, student);
     }
 
     private void ShowAddressViewer(ContactItem contact)

LehrerApp.Desktop/Views/Students/StudentPickerDialog.axaml

@@ -0,0 +1,41 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Students"
+        xmlns:vmg="clr-namespace:LehrerApp.Desktop.ViewModels.Groups"
+        x:Class="LehrerApp.Desktop.Views.Students.StudentPickerDialog"
+        x:DataType="vm:StudentPickerDialogViewModel"
+        Title="Schüler wählen"
+        Width="380" Height="480"
+        CanResize="False" WindowStartupLocation="CenterOwner">
+
+  <Grid RowDefinitions="Auto,*,Auto" Margin="24">
+
+    <StackPanel Grid.Row="0" Spacing="12" Margin="0,0,0,12">
+      <TextBlock Text="Schüler wählen" Classes="dialogtitle"/>
+      <TextBox Text="{Binding SearchText}"
+               PlaceholderText="Schüler suchen …"
+               x:Name="SearchBox"/>
+    </StackPanel>
+
+    <ListBox Grid.Row="1"
+             ItemsSource="{Binding Students}"
+             SelectedItem="{Binding SelectedStudent}"
+             BorderThickness="1">
+      <ListBox.ItemTemplate>
+        <DataTemplate x:DataType="vmg:StudentPickerItem">
+          <TextBlock Text="{Binding FullName}" Padding="4,2"/>
+        </DataTemplate>
+      </ListBox.ItemTemplate>
+    </ListBox>
+
+    <StackPanel Grid.Row="2" Spacing="12" Margin="0,16,0,0">
+      <TextBlock Text="{Binding ValidationMessage}" Foreground="Red" FontSize="12"
+                 IsVisible="{Binding ValidationMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+      <Grid ColumnDefinitions="*,8,*">
+        <Button Grid.Column="0" Content="Abbrechen" HorizontalAlignment="Stretch" Click="OnCancel"/>
+        <Button Grid.Column="2" Content="Weiter" HorizontalAlignment="Stretch" Click="OnSave"/>
+      </Grid>
+    </StackPanel>
+
+  </Grid>
+</Window>

LehrerApp.Desktop/Views/Students/StudentPickerDialog.axaml.cs

@@ -0,0 +1,25 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using LehrerApp.Desktop.ViewModels.Students;
+
+namespace LehrerApp.Desktop.Views.Students;
+
+public partial class StudentPickerDialog : Window
+{
+    public StudentPickerDialog() => InitializeComponent();
+
+    protected override void OnOpened(EventArgs e)
+    {
+        base.OnOpened(e);
+        this.FindControl<TextBox>("SearchBox")?.Focus();
+    }
+
+    private void OnSave(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is not StudentPickerDialogViewModel vm) return;
+        vm.SelectCommand.Execute(null);
+        if (vm.Result is not null) Close(vm.Result);
+    }
+
+    private void OnCancel(object? sender, RoutedEventArgs e) => Close(null);
+}