Initial

2026-03-29 23:47:31 +02:00
commit 216d5d2280
75 changed files with 5702 additions and 0 deletions
--- a/LehrerApp.Desktop/App.axaml
+++ b/LehrerApp.Desktop/App.axaml
@@ -0,0 +1,18 @@
+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="LehrerApp.Desktop.App"
+             RequestedThemeVariant="Default">
+
+  <Application.Styles>
+    <FluentTheme />
+  </Application.Styles>
+
+  <Application.Resources>
+    <ResourceDictionary>
+      <ResourceDictionary.MergedDictionaries>
+        <ResourceInclude Source="avares://LehrerApp.Desktop/Views/DataTemplates.axaml"/>
+      </ResourceDictionary.MergedDictionaries>
+    </ResourceDictionary>
+  </Application.Resources>
+
+</Application>
--- a/LehrerApp.Desktop/App.axaml.cs
+++ b/LehrerApp.Desktop/App.axaml.cs
@@ -0,0 +1,33 @@
+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Markup.Xaml;
+using LehrerApp.Desktop.ViewModels;
+using LehrerApp.Desktop.Views;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LehrerApp.Desktop;
+
+public class App : Application
+{
+    public static IServiceProvider Services { get; private set; } = null!;
+
+    public override void Initialize()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        Services = AppBootstrapper.BuildServices();
+
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            desktop.MainWindow = new MainWindow
+            {
+                DataContext = Services.GetRequiredService<MainWindowViewModel>(),
+            };
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+}
--- a/LehrerApp.Desktop/AppBootstrapper.cs
+++ b/LehrerApp.Desktop/AppBootstrapper.cs
@@ -0,0 +1,181 @@
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Services;
+using LehrerApp.Data;
+using LehrerApp.Data.Repositories;
+using LehrerApp.Desktop.ViewModels;
+using LehrerApp.Desktop.ViewModels.Groups;
+using LehrerApp.Desktop.ViewModels.Students;
+using LehrerApp.Sync;
+using LehrerApp.Sync.Crypto;
+using LehrerApp.Sync.Models;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LehrerApp.Desktop;
+
+public static class AppBootstrapper
+{
+    public static IServiceProvider BuildServices()
+    {
+        var services = new ServiceCollection();
+
+        // ── Pfade ─────────────────────────────────────────────────────────────
+        var appData = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+            "LehrerApp");
+        Directory.CreateDirectory(appData);
+
+        var dbPath    = Path.Combine(appData, "lehrerapp.db");
+        var queuePath = Path.Combine(appData, "syncqueue.db");
+        var keyPath   = Path.Combine(appData, "sync.key");
+
+        // ── Datenbank ─────────────────────────────────────────────────────────
+        services.AddSingleton(_ => new LiteDbContext(dbPath));
+
+        // ── Repositories ──────────────────────────────────────────────────────
+        services.AddSingleton<IStudentRepository, StudentRepository>();
+        services.AddSingleton<IGroupRepository, GroupRepository>();
+        services.AddSingleton<IEnrollmentRepository, EnrollmentRepository>();
+        services.AddSingleton<IExamRepository, ExamRepository>();
+        services.AddSingleton<IExamResultRepository, ExamResultRepository>();
+        services.AddSingleton<IGradeRepository, GradeRepository>();
+        services.AddSingleton<IUnitRepository, UnitRepository>();
+        services.AddSingleton<ILessonRepository, LessonRepository>();
+        services.AddSingleton<IDocumentationRepository, DocumentationRepository>();
+        services.AddSingleton<IWorkTaskRepository, WorkTaskRepository>();
+        services.AddSingleton<ITimeEntryRepository, TimeEntryRepository>();
+
+        // ── Core Services ─────────────────────────────────────────────────────
+        services.AddSingleton<GradingService>();
+        services.AddSingleton<SchoolYearService>();
+
+        // ── Sync ──────────────────────────────────────────────────────────────
+        services.AddSingleton(_ => new EventQueue(queuePath));
+        services.AddSingleton(sp =>
+            new ConflictResolver(sp.GetRequiredService<EventQueue>()));
+
+        // Schlüssel laden oder neu generieren
+        services.AddSingleton<byte[]>(_ =>
+        {
+            var key = SyncCrypto.LoadKey(keyPath) ?? SyncCrypto.GenerateKey();
+            SyncCrypto.SaveKey(key, keyPath);
+            return key;
+        });
+
+        // EventApplier – wendet gezogene Events auf LiteDB an
+        services.AddSingleton<EventApplier>(sp => new EventApplier(
+            key:          sp.GetRequiredService<byte[]>(),
+            students:     sp.GetRequiredService<IStudentRepository>(),
+            groups:       sp.GetRequiredService<IGroupRepository>(),
+            enrollments:  sp.GetRequiredService<IEnrollmentRepository>(),
+            exams:        sp.GetRequiredService<IExamRepository>(),
+            examResults:  sp.GetRequiredService<IExamResultRepository>(),
+            grades:       sp.GetRequiredService<IGradeRepository>(),
+            units:        sp.GetRequiredService<IUnitRepository>(),
+            lessons:      sp.GetRequiredService<ILessonRepository>(),
+            docs:         sp.GetRequiredService<IDocumentationRepository>(),
+            tasks:        sp.GetRequiredService<IWorkTaskRepository>(),
+            timeEntries:  sp.GetRequiredService<ITimeEntryRepository>()));
+
+        // SyncEngine + ReadableSnapshotService nur wenn Server konfiguriert
+        var serverUrl  = LoadServerUrl(appData);
+        var deviceId   = LoadOrCreateDeviceId(appData);
+
+        services.AddSingleton<SyncEngine?>(sp =>
+        {
+            if (string.IsNullOrEmpty(serverUrl)) return null;
+
+            var http   = BuildHttpClient(serverUrl, appData);
+            var config = new SyncConfig
+            {
+                ServerUrl               = serverUrl,
+                DeviceId                = deviceId,
+                DeviceType              = DeviceType.Desktop,
+                AutoSyncIntervalMinutes = 5,
+            };
+            return new SyncEngine(
+                sp.GetRequiredService<EventQueue>(),
+                sp.GetRequiredService<ConflictResolver>(),
+                http,
+                config);
+        });
+
+        services.AddSingleton<ReadableSnapshotService?>(sp =>
+        {
+            if (string.IsNullOrEmpty(serverUrl)) return null;
+
+            return new ReadableSnapshotService(
+                http:        BuildHttpClient(serverUrl, appData),
+                students:    sp.GetRequiredService<IStudentRepository>(),
+                groups:      sp.GetRequiredService<IGroupRepository>(),
+                enrollments: sp.GetRequiredService<IEnrollmentRepository>(),
+                exams:       sp.GetRequiredService<IExamRepository>(),
+                examResults: sp.GetRequiredService<IExamResultRepository>(),
+                grades:      sp.GetRequiredService<IGradeRepository>(),
+                units:       sp.GetRequiredService<IUnitRepository>(),
+                lessons:     sp.GetRequiredService<ILessonRepository>(),
+                tasks:       sp.GetRequiredService<IWorkTaskRepository>(),
+                schoolYear:  sp.GetRequiredService<SchoolYearService>(),
+                deviceId:    deviceId);
+        });
+
+        services.AddSingleton<SnapshotService?>(sp =>
+        {
+            if (string.IsNullOrEmpty(serverUrl)) return null;
+
+            return new SnapshotService(
+                http:       BuildHttpClient(serverUrl, appData),
+                db:         sp.GetRequiredService<LiteDbContext>(),
+                syncKey:    sp.GetRequiredService<byte[]>(),
+                deviceType: DeviceType.Desktop,
+                dbPath:     dbPath,
+                keyPath:    keyPath);
+        });
+
+        // ── ViewModels ────────────────────────────────────────────────────────
+        services.AddSingleton<MainWindowViewModel>();
+        services.AddSingleton<DashboardViewModel>();
+        services.AddTransient<GroupListViewModel>();
+        services.AddTransient<GroupDetailViewModel>();
+        services.AddTransient<StudentListViewModel>();
+        services.AddTransient<StudentDetailViewModel>();
+        services.AddSingleton<SyncStatusViewModel>();
+        services.AddTransient<DevicePairingViewModel>(sp =>
+            new DevicePairingViewModel(
+                sp.GetRequiredService<SnapshotService?>()
+                ?? throw new InvalidOperationException(
+                    "Kein Server konfiguriert.")));
+
+        return services.BuildServiceProvider();
+    }
+
+    // ── Hilfsmethoden ─────────────────────────────────────────────────────────
+
+    private static HttpClient BuildHttpClient(string serverUrl, string appData)
+    {
+        var http = new HttpClient { BaseAddress = new Uri(serverUrl) };
+        var tokenPath = Path.Combine(appData, "auth.token");
+        if (File.Exists(tokenPath))
+        {
+            var token = File.ReadAllText(tokenPath).Trim();
+            http.DefaultRequestHeaders.Authorization =
+                new System.Net.Http.Headers.AuthenticationHeaderValue(
+                    "Bearer", token);
+        }
+        return http;
+    }
+
+    private static string LoadServerUrl(string appData)
+    {
+        var path = Path.Combine(appData, "server.txt");
+        return File.Exists(path) ? File.ReadAllText(path).Trim() : "";
+    }
+
+    private static string LoadOrCreateDeviceId(string appData)
+    {
+        var path = Path.Combine(appData, "device.id");
+        if (File.Exists(path)) return File.ReadAllText(path).Trim();
+        var id = Guid.NewGuid().ToString();
+        File.WriteAllText(path, id);
+        return id;
+    }
+}
--- a/LehrerApp.Desktop/LehrerApp.Desktop.csproj
+++ b/LehrerApp.Desktop/LehrerApp.Desktop.csproj
@@ -0,0 +1,32 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <LangVersion>latest</LangVersion>
+    <BuiltInComInteropSupport>true</BuiltInComInteropSupport>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\LehrerApp.Core\LehrerApp.Core.csproj" />
+    <ProjectReference Include="..\LehrerApp.Data\LehrerApp.Data.csproj" />
+    <ProjectReference Include="..\LehrerApp.Sync\LehrerApp.Sync.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <!-- Avalonia 11.3.x – aktuell stabiler Branch -->
+    <PackageReference Include="Avalonia" />
+    <PackageReference Include="Avalonia.Desktop" />
+    <PackageReference Include="Avalonia.Themes.Fluent" />
+    <PackageReference Include="Avalonia.Fonts.Inter" />
+    <!-- ReactiveUI aus Avalonia 11.3 entfernt – CommunityToolkit.Mvvm reicht -->
+    <PackageReference Include="CommunityToolkit.Mvvm" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <AvaloniaResource Include="Assets\**" />
+  </ItemGroup>
+</Project>
--- a/LehrerApp.Desktop/Program.cs
+++ b/LehrerApp.Desktop/Program.cs
@@ -0,0 +1,16 @@
+using Avalonia;
+
+namespace LehrerApp.Desktop;
+
+class Program
+{
+    [STAThread]
+    public static void Main(string[] args) =>
+        BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+
+    public static AppBuilder BuildAvaloniaApp() =>
+        AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+            .WithInterFont()
+            .LogToTrace();
+}
--- a/LehrerApp.Desktop/ViewModels/DashboardViewModel.cs
+++ b/LehrerApp.Desktop/ViewModels/DashboardViewModel.cs
@@ -0,0 +1,136 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Core.Services;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels;
+
+public partial class DashboardViewModel : ObservableObject
+{
+    private readonly IGroupRepository _groups;
+    private readonly ILessonRepository _lessons;
+    private readonly IWorkTaskRepository _tasks;
+    private readonly SchoolYearService _schoolYearService;
+
+    [ObservableProperty] private string _greeting = "";
+    [ObservableProperty] private string _currentDate = "";
+    [ObservableProperty] private string _currentSchoolYear = "";
+
+    public ObservableCollection<LessonItem> TodaysLessons { get; } = [];
+    public ObservableCollection<TaskItem> OpenTasks { get; } = [];
+    public ObservableCollection<GroupChip> CurrentGroups { get; } = [];
+
+    public DashboardViewModel(
+        IGroupRepository groups,
+        ILessonRepository lessons,
+        IWorkTaskRepository tasks,
+        SchoolYearService schoolYearService)
+    {
+        _groups = groups;
+        _lessons = lessons;
+        _tasks = tasks;
+        _schoolYearService = schoolYearService;
+
+        Load();
+    }
+
+    private void Load()
+    {
+        var now = DateTime.Now;
+        var today = DateOnly.FromDateTime(now);
+
+        CurrentDate = now.ToString("dddd, d. MMMM yyyy",
+            new System.Globalization.CultureInfo("de-DE"));
+        CurrentSchoolYear = _schoolYearService.CurrentSchoolYear();
+        Greeting = now.Hour < 12 ? "Guten Morgen" :
+                   now.Hour < 18 ? "Guten Tag" : "Guten Abend";
+
+        // Heutige Stunden
+        TodaysLessons.Clear();
+        var schoolYear = _schoolYearService.CurrentSchoolYear();
+        var allGroups = _groups.GetBySchoolYear(schoolYear)
+            .ToDictionary(g => g.Id);
+
+        var todayLessons = allGroups.Keys
+            .SelectMany(gid => _lessons.GetByGroupAndDate(gid, today))
+            .OrderBy(l => l.LessonNumber)
+            .ToList();
+
+        foreach (var lesson in todayLessons)
+        {
+            if (!allGroups.TryGetValue(lesson.GroupId, out var group)) continue;
+            TodaysLessons.Add(new LessonItem
+            {
+                GroupName = group.Name,
+                Topic = lesson.Topic,
+                Status = lesson.Status,
+            });
+        }
+
+        // Offene Aufgaben (mit Fälligkeit)
+        OpenTasks.Clear();
+        var openTasks = _tasks.GetByStatus(WorkTaskStatus.Open)
+            .Concat(_tasks.GetByStatus(WorkTaskStatus.InProgress))
+            .OrderBy(t => t.DueDate ?? DateOnly.MaxValue)
+            .Take(5);
+
+        foreach (var task in openTasks)
+        {
+            var isOverdue = task.DueDate.HasValue && task.DueDate < today;
+            var isDueSoon = task.DueDate.HasValue &&
+                            task.DueDate >= today &&
+                            task.DueDate <= today.AddDays(3);
+
+            OpenTasks.Add(new TaskItem
+            {
+                Title = task.Title,
+                DueDate = task.DueDate?.ToString("dd.MM.") ?? "",
+                IsOverdue = isOverdue,
+                IsDueSoon = isDueSoon,
+                Status = task.Status,
+            });
+        }
+
+        // Aktuelle Lerngruppen als Chips
+        CurrentGroups.Clear();
+        foreach (var group in _groups.GetBySchoolYear(schoolYear)
+                     .OrderBy(g => g.Name))
+        {
+            CurrentGroups.Add(new GroupChip
+            {
+                GroupId = group.Id,
+                Name = group.Name,
+                Subject = group.Subject ?? "",
+            });
+        }
+    }
+
+    [RelayCommand]
+    private void Refresh() => Load();
+}
+
+// Anzeigemodelle für Dashboard-Widgets
+public class LessonItem
+{
+    public string GroupName { get; set; } = "";
+    public string Topic { get; set; } = "";
+    public LessonStatus Status { get; set; }
+}
+
+public class TaskItem
+{
+    public string Title { get; set; } = "";
+    public string DueDate { get; set; } = "";
+    public bool IsOverdue { get; set; }
+    public bool IsDueSoon { get; set; }
+    public WorkTaskStatus Status { get; set; }
+}
+
+public class GroupChip
+{
+    public Guid GroupId { get; set; }
+    public string Name { get; set; } = "";
+    public string Subject { get; set; } = "";
+}
--- a/LehrerApp.Desktop/ViewModels/DevicePairingViewModel.cs
+++ b/LehrerApp.Desktop/ViewModels/DevicePairingViewModel.cs
@@ -0,0 +1,158 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Data;
+using LehrerApp.Sync;
+using LehrerApp.Sync.Models;
+
+namespace LehrerApp.Desktop.ViewModels;
+
+/// <summary>
+/// Steuert den Dialog zum Einrichten eines neuen Geräts.
+///
+/// Zwei Modi:
+///   Sender  → "Neues Gerät hinzufügen" – erzeugt Snapshot und zeigt Code
+///   Empfänger → "Mit bestehendem Account verbinden" – Code eingeben, Restore
+/// </summary>
+public partial class DevicePairingViewModel : ObservableObject
+{
+    private readonly SnapshotService _snapshotService;
+
+    // ── Gemeinsamer State ─────────────────────────────────────────────────────
+
+    [ObservableProperty] private PairingMode _mode = PairingMode.SelectMode;
+    [ObservableProperty] private bool _isBusy;
+    [ObservableProperty] private string _statusMessage = "";
+    [ObservableProperty] private int _progressPercent;
+    [ObservableProperty] private bool _isError;
+    [ObservableProperty] private bool _isComplete;
+
+    // ── Sender-State ─────────────────────────────────────────────────────────
+
+    [ObservableProperty] private string _generatedCode = "";
+    [ObservableProperty] private DateTime _codeExpiresAt;
+    [ObservableProperty] private string _codeExpiresText = "";
+
+    // ── Empfänger-State ───────────────────────────────────────────────────────
+
+    [ObservableProperty] private string _inputCode = "";
+
+    public DevicePairingViewModel(SnapshotService snapshotService)
+    {
+        _snapshotService = snapshotService;
+        _snapshotService.ProgressChanged += OnProgress;
+    }
+
+    // ── Navigation zwischen Modi ──────────────────────────────────────────────
+
+    [RelayCommand]
+    private void SelectSender() => Mode = PairingMode.Sender;
+
+    [RelayCommand]
+    private void SelectReceiver() => Mode = PairingMode.Receiver;
+
+    [RelayCommand]
+    private void Back()
+    {
+        Mode = PairingMode.SelectMode;
+        Reset();
+    }
+
+    // ── Sender: Snapshot erstellen ────────────────────────────────────────────
+
+    [RelayCommand(CanExecute = nameof(CanCreateSnapshot))]
+    private async Task CreateSnapshotAsync()
+    {
+        IsBusy = true;
+        IsError = false;
+        IsComplete = false;
+
+        try
+        {
+            var result = await _snapshotService.CreateAndUploadAsync();
+
+            GeneratedCode   = result.Code;
+            CodeExpiresAt   = result.ExpiresAt;
+            CodeExpiresText = $"Gültig bis {result.ExpiresAt:HH:mm} Uhr " +
+                              $"({result.ExpiresAt:dd.MM.yyyy})";
+            Mode            = PairingMode.SenderShowCode;
+        }
+        catch (Exception ex)
+        {
+            IsError        = true;
+            StatusMessage  = $"Fehler: {ex.Message}";
+        }
+        finally
+        {
+            IsBusy = false;
+        }
+    }
+
+    private bool CanCreateSnapshot() => !IsBusy;
+
+    // ── Empfänger: Snapshot wiederherstellen ──────────────────────────────────
+
+    [RelayCommand(CanExecute = nameof(CanRestore))]
+    private async Task RestoreAsync(string targetDbPath)
+    {
+        IsBusy = true;
+        IsError = false;
+        IsComplete = false;
+
+        try
+        {
+            // Schlüssel wird aus dem Code extrahiert und lokal gespeichert
+            // → App-Neustart lädt ihn automatisch
+            await _snapshotService.RestoreFromCodeAsync(
+                InputCode.Trim(), targetDbPath);
+
+            IsComplete    = true;
+            StatusMessage = "Erfolgreich! Bitte die App neu starten.";
+            Mode          = PairingMode.ReceiverDone;
+        }
+        catch (SnapshotNotFoundException ex)
+        {
+            IsError       = true;
+            StatusMessage = ex.Message;
+        }
+        catch (Exception ex)
+        {
+            IsError       = true;
+            StatusMessage = $"Fehler beim Wiederherstellen: {ex.Message}";
+        }
+        finally
+        {
+            IsBusy = false;
+        }
+    }
+
+    private bool CanRestore() =>
+        !IsBusy && InputCode.Trim().Length >= 5;
+
+    // ── Hilfsmethoden ─────────────────────────────────────────────────────────
+
+    private void OnProgress(SnapshotProgress progress)
+    {
+        StatusMessage   = progress.Message;
+        ProgressPercent = progress.PercentComplete;
+    }
+
+    private void Reset()
+    {
+        StatusMessage   = "";
+        ProgressPercent = 0;
+        IsError         = false;
+        IsComplete      = false;
+        GeneratedCode   = "";
+        InputCode       = "";
+        IsBusy          = false;
+    }
+}
+
+public enum PairingMode
+{
+    SelectMode,       // Startbildschirm: Sender oder Empfänger wählen
+    Sender,           // Sender bereit, Snapshot erstellen
+    SenderShowCode,   // Code wird angezeigt
+    Receiver,         // Code-Eingabe
+    ReceiverDone,     // Erfolgreich wiederhergestellt
+}
--- a/LehrerApp.Desktop/ViewModels/Groups/AddGroupDialogViewModel.cs
+++ b/LehrerApp.Desktop/ViewModels/Groups/AddGroupDialogViewModel.cs
@@ -0,0 +1,90 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Core.Services;
+
+namespace LehrerApp.Desktop.ViewModels.Groups;
+
+public partial class AddGroupDialogViewModel : ObservableObject
+{
+    private readonly IGroupRepository _groups;
+    private readonly SchoolYearService _schoolYearService;
+
+    [ObservableProperty] private string _name = "";
+    [ObservableProperty] private string _subject = "";
+    [ObservableProperty] private GroupType _type = GroupType.Course;
+    [ObservableProperty] private int _gradeLevel = 10;
+    [ObservableProperty] private GradingSystem _gradingSystem = GradingSystem.Grades1To6;
+    [ObservableProperty] private int? _hoursPerWeek;
+    [ObservableProperty] private string _selectedSchoolYear = "";
+    [ObservableProperty] private string _validationMessage = "";
+
+    public List<string> SchoolYears { get; }
+    public List<GroupTypeItem> GroupTypes { get; } =
+    [
+        new(GroupType.Course, "Fachkurs"),
+        new(GroupType.Class, "Klassenverband"),
+    ];
+    public List<GradingSystemItem> GradingSystems { get; } =
+    [
+        new(GradingSystem.Grades1To6, "Noten 1–6 (Sek I)"),
+        new(GradingSystem.Points0To15, "Punkte 0–15 (Oberstufe)"),
+    ];
+
+    // Wird vom Dialog aufgerufen wenn OK geklickt wurde
+    public LearningGroup? Result { get; private set; }
+
+    public AddGroupDialogViewModel(
+        IGroupRepository groups,
+        SchoolYearService schoolYearService)
+    {
+        _groups = groups;
+        _schoolYearService = schoolYearService;
+        SchoolYears = schoolYearService.RecentSchoolYears(3);
+        SelectedSchoolYear = schoolYearService.CurrentSchoolYear();
+
+        // Automatisch Notensystem vorschlagen wenn Klassenstufe sich ändert
+        PropertyChanged += (_, e) =>
+        {
+            if (e.PropertyName == nameof(GradeLevel))
+                GradingSystem = GradeLevel >= 11
+                    ? GradingSystem.Points0To15
+                    : GradingSystem.Grades1To6;
+        };
+    }
+
+    [RelayCommand]
+    private bool Save()
+    {
+        // Validierung
+        if (string.IsNullOrWhiteSpace(Name))
+        {
+            ValidationMessage = "Bitte einen Namen eingeben.";
+            return false;
+        }
+        if (GradeLevel is < 1 or > 13)
+        {
+            ValidationMessage = "Klassenstufe muss zwischen 1 und 13 liegen.";
+            return false;
+        }
+
+        Result = new LearningGroup
+        {
+            Name = Name.Trim(),
+            Subject = string.IsNullOrWhiteSpace(Subject) ? null : Subject.Trim(),
+            Type = Type,
+            GradeLevel = GradeLevel,
+            GradingSystem = GradingSystem,
+            SchoolYear = SelectedSchoolYear,
+            HoursPerWeek = HoursPerWeek,
+        };
+
+        _groups.Save(Result);
+        ValidationMessage = "";
+        return true;
+    }
+}
+
+public record GroupTypeItem(GroupType Value, string Label);
+public record GradingSystemItem(GradingSystem Value, string Label);
--- a/LehrerApp.Desktop/ViewModels/Groups/GroupViewModels.cs
+++ b/LehrerApp.Desktop/ViewModels/Groups/GroupViewModels.cs
@@ -0,0 +1,208 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Core.Services;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels.Groups;
+
+// ── Gruppenliste ──────────────────────────────────────────────────────────────
+
+public partial class GroupListViewModel : ObservableObject
+{
+    private readonly IGroupRepository _groups;
+    private readonly SchoolYearService _schoolYearService;
+
+    [ObservableProperty] private string _selectedSchoolYear = "";
+    [ObservableProperty] private string _searchText = "";
+    [ObservableProperty] private GroupListItem? _selectedGroup;
+
+    public ObservableCollection<string> SchoolYears { get; } = [];
+    public ObservableCollection<GroupListItem> Groups { get; } = [];
+
+    public GroupListViewModel(
+        IGroupRepository groups,
+        SchoolYearService schoolYearService)
+    {
+        _groups = groups;
+        _schoolYearService = schoolYearService;
+
+        foreach (var y in schoolYearService.RecentSchoolYears())
+            SchoolYears.Add(y);
+
+        SelectedSchoolYear = schoolYearService.CurrentSchoolYear();
+        LoadGroups();
+    }
+
+    partial void OnSelectedSchoolYearChanged(string value) => LoadGroups();
+    partial void OnSearchTextChanged(string value) => LoadGroups();
+
+    private void LoadGroups()
+    {
+        Groups.Clear();
+        var all = _groups.GetBySchoolYear(SelectedSchoolYear);
+
+        var filtered = string.IsNullOrWhiteSpace(SearchText)
+            ? all
+            : all.Where(g =>
+                g.Name.Contains(SearchText, StringComparison.OrdinalIgnoreCase) ||
+                (g.Subject?.Contains(SearchText, StringComparison.OrdinalIgnoreCase) ?? false));
+
+        foreach (var g in filtered)
+            Groups.Add(new GroupListItem(g));
+    }
+
+    [RelayCommand]
+    private void AddGroup()
+    {
+        // TODO: Dialog öffnen
+    }
+
+    [RelayCommand]
+    private void Refresh() => LoadGroups();
+}
+
+public class GroupListItem
+{
+    public Guid Id { get; }
+    public string Name { get; }
+    public string Subject { get; }
+    public string SchoolYear { get; }
+    public int GradeLevel { get; }
+    public string TypeLabel { get; }
+    public string GradingLabel { get; }
+
+    public GroupListItem(LearningGroup g)
+    {
+        Id = g.Id;
+        Name = g.Name;
+        Subject = g.Subject ?? "";
+        SchoolYear = g.SchoolYear;
+        GradeLevel = g.GradeLevel;
+        TypeLabel = g.Type == GroupType.Class ? "Klasse" : "Kurs";
+        GradingLabel = g.GradingSystem == GradingSystem.Grades1To6
+            ? "Noten 1–6"
+            : "Punkte 0–15";
+    }
+}
+
+// ── Gruppendetail (Tab-Navigation) ────────────────────────────────────────────
+
+public partial class GroupDetailViewModel : ObservableObject
+{
+    private readonly IGroupRepository _groups;
+    private readonly IStudentRepository _students;
+    private readonly IEnrollmentRepository _enrollments;
+    private readonly IExamRepository _exams;
+    private readonly SchoolYearService _schoolYearService;
+
+    [ObservableProperty] private LearningGroup? _group;
+    [ObservableProperty] private string _groupTitle = "";
+    [ObservableProperty] private int _studentCount;
+    [ObservableProperty] private GroupTab _activeTab = GroupTab.Overview;
+
+    // Sub-ViewModels für Tabs – lazy geladen
+    public ObservableCollection<StudentSummary> Students { get; } = [];
+    public ObservableCollection<ExamSummary> Exams { get; } = [];
+
+    public GroupDetailViewModel(
+        IGroupRepository groups,
+        IStudentRepository students,
+        IEnrollmentRepository enrollments,
+        IExamRepository exams,
+        SchoolYearService schoolYearService)
+    {
+        _groups = groups;
+        _students = students;
+        _enrollments = enrollments;
+        _exams = exams;
+        _schoolYearService = schoolYearService;
+    }
+
+    public void LoadGroup(Guid groupId)
+    {
+        Group = _groups.GetById(groupId);
+        if (Group is null) return;
+
+        GroupTitle = $"{Group.Name} · {Group.SchoolYear}";
+        LoadStudents();
+        LoadExams();
+    }
+
+    [RelayCommand]
+    private void SwitchTab(GroupTab tab)
+    {
+        ActiveTab = tab;
+    }
+
+    private void LoadStudents()
+    {
+        if (Group is null) return;
+        Students.Clear();
+
+        var enrolled = _students.GetByGroup(Group.Id, Group.SchoolYear);
+        StudentCount = enrolled.Count;
+
+        foreach (var s in enrolled)
+            Students.Add(new StudentSummary(s));
+    }
+
+    private void LoadExams()
+    {
+        if (Group is null) return;
+        Exams.Clear();
+
+        foreach (var e in _exams.GetByGroup(Group.Id))
+            Exams.Add(new ExamSummary(e));
+    }
+
+    [RelayCommand]
+    private void AddStudent()
+    {
+        // TODO: Schüler-Auswahl-Dialog
+    }
+
+    [RelayCommand]
+    private void AddExam()
+    {
+        // TODO: Klausur-Erstellen-Dialog
+    }
+}
+
+public enum GroupTab { Overview, Students, Exams, Grades, Planner, Documentation }
+
+public class StudentSummary
+{
+    public Guid Id { get; }
+    public string FullName { get; }
+
+    public StudentSummary(Core.Models.Student s)
+    {
+        Id = s.Id;
+        FullName = s.FullName;
+    }
+}
+
+public class ExamSummary
+{
+    public Guid Id { get; }
+    public string Title { get; }
+    public string Date { get; }
+    public string Status { get; }
+
+    public ExamSummary(Core.Models.Exam e)
+    {
+        Id = e.Id;
+        Title = e.Title;
+        Date = e.Date.ToString("dd.MM.yyyy");
+        Status = e.Status switch
+        {
+            ExamStatus.Planned   => "Geplant",
+            ExamStatus.Conducted => "Durchgeführt",
+            ExamStatus.Graded    => "Korrigiert",
+            ExamStatus.Returned  => "Zurückgegeben",
+            _ => "",
+        };
+    }
+}
--- a/LehrerApp.Desktop/ViewModels/MainWindowViewModel.cs
+++ b/LehrerApp.Desktop/ViewModels/MainWindowViewModel.cs
@@ -0,0 +1,87 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Services;
+using LehrerApp.Desktop.ViewModels.Groups;
+using LehrerApp.Desktop.ViewModels.Students;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LehrerApp.Desktop.ViewModels;
+
+public partial class MainWindowViewModel : ObservableObject
+{
+    private readonly IServiceProvider _services;
+
+    [ObservableProperty]
+    private ObservableObject? _currentPage;
+
+    [ObservableProperty]
+    private NavItem _activeNavItem = NavItem.Dashboard;
+
+    // ── Fehlende Property die im MainWindow.axaml referenziert wird ───────────
+    [ObservableProperty]
+    private string _currentSchoolYear = "";
+
+    public MainWindowViewModel(
+        IServiceProvider services,
+        DashboardViewModel dashboard,
+        SchoolYearService schoolYearService)
+    {
+        _services = services;
+        CurrentPage = dashboard;
+        CurrentSchoolYear = schoolYearService.CurrentSchoolYear();
+    }
+
+    // ── Navigation ────────────────────────────────────────────────────────────
+
+    [RelayCommand]
+    private void NavigateTo(NavItem item)
+    {
+        ActiveNavItem = item;
+        CurrentPage = item switch
+        {
+            NavItem.Dashboard  => _services.GetRequiredService<DashboardViewModel>(),
+            NavItem.Groups     => _services.GetRequiredService<GroupListViewModel>(),
+            NavItem.Students   => _services.GetRequiredService<StudentListViewModel>(),
+            NavItem.Exams      => CreatePlaceholder("Klausuren"),
+            NavItem.Planner    => CreatePlaceholder("Unterrichtsplanung"),
+            NavItem.Workload   => CreatePlaceholder("Arbeitszeit"),
+            NavItem.Settings   => CreatePlaceholder("Einstellungen"),
+            _ => CurrentPage,
+        };
+    }
+
+    public void NavigateToGroup(Guid groupId)
+    {
+        ActiveNavItem = NavItem.Groups;
+        var vm = _services.GetRequiredService<GroupDetailViewModel>();
+        vm.LoadGroup(groupId);
+        CurrentPage = vm;
+    }
+
+    public void NavigateToStudent(Guid studentId)
+    {
+        ActiveNavItem = NavItem.Students;
+        var vm = _services.GetRequiredService<StudentDetailViewModel>();
+        vm.LoadStudent(studentId);
+        CurrentPage = vm;
+    }
+
+    private static PlaceholderViewModel CreatePlaceholder(string title) =>
+        new() { Title = title };
+}
+
+public enum NavItem
+{
+    Dashboard,
+    Groups,
+    Students,
+    Exams,
+    Planner,
+    Workload,
+    Settings,
+}
+
+public partial class PlaceholderViewModel : ObservableObject
+{
+    [ObservableProperty] private string _title = "";
+}
--- a/LehrerApp.Desktop/ViewModels/Students/StudentViewModels.cs
+++ b/LehrerApp.Desktop/ViewModels/Students/StudentViewModels.cs
@@ -0,0 +1,223 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels.Students;
+
+// ── Schülerliste ──────────────────────────────────────────────────────────────
+
+public partial class StudentListViewModel : ObservableObject
+{
+    private readonly IStudentRepository _students;
+
+    [ObservableProperty] private string _searchText = "";
+    [ObservableProperty] private bool _showInactive;
+    [ObservableProperty] private StudentListItem? _selectedStudent;
+
+    public ObservableCollection<StudentListItem> Students { get; } = [];
+
+    public StudentListViewModel(IStudentRepository students)
+    {
+        _students = students;
+        LoadStudents();
+    }
+
+    partial void OnSearchTextChanged(string value) => LoadStudents();
+    partial void OnShowInactiveChanged(bool value) => LoadStudents();
+
+    private void LoadStudents()
+    {
+        Students.Clear();
+        var all = _students.GetAll(includeInactive: ShowInactive);
+
+        var filtered = string.IsNullOrWhiteSpace(SearchText)
+            ? all
+            : all.Where(s =>
+                s.LastName.Contains(SearchText, StringComparison.OrdinalIgnoreCase) ||
+                s.FirstName.Contains(SearchText, StringComparison.OrdinalIgnoreCase));
+
+        foreach (var s in filtered)
+            Students.Add(new StudentListItem(s));
+    }
+
+    [RelayCommand]
+    private void AddStudent()
+    {
+        // TODO: Neuer-Schüler-Dialog
+    }
+
+    [RelayCommand]
+    private void Refresh() => LoadStudents();
+}
+
+public class StudentListItem
+{
+    public Guid Id { get; }
+    public string FullName { get; }
+    public string DateOfBirth { get; }
+    public bool IsActive { get; }
+
+    public StudentListItem(Student s)
+    {
+        Id = s.Id;
+        FullName = s.FullName;
+        DateOfBirth = s.DateOfBirth?.ToString("dd.MM.yyyy") ?? "";
+        IsActive = s.IsActive;
+    }
+}
+
+// ── Schülerdetail ─────────────────────────────────────────────────────────────
+
+public partial class StudentDetailViewModel : ObservableObject
+{
+    private readonly IStudentRepository _students;
+    private readonly IEnrollmentRepository _enrollments;
+    private readonly IGroupRepository _groups;
+    private readonly IGradeRepository _grades;
+    private readonly IDocumentationRepository _docs;
+
+    [ObservableProperty] private Student? _student;
+    [ObservableProperty] private string _studentTitle = "";
+    [ObservableProperty] private StudentTab _activeTab = StudentTab.Overview;
+    [ObservableProperty] private bool _isEditing;
+
+    // Bearbeitbare Felder
+    [ObservableProperty] private string _editFirstName = "";
+    [ObservableProperty] private string _editLastName = "";
+    [ObservableProperty] private string _editNotes = "";
+
+    public ObservableCollection<EnrollmentEntry> Enrollments { get; } = [];
+    public ObservableCollection<GradeEntry> Grades { get; } = [];
+    public ObservableCollection<DocEntry> Documentation { get; } = [];
+
+    public StudentDetailViewModel(
+        IStudentRepository students,
+        IEnrollmentRepository enrollments,
+        IGroupRepository groups,
+        IGradeRepository grades,
+        IDocumentationRepository docs)
+    {
+        _students = students;
+        _enrollments = enrollments;
+        _groups = groups;
+        _grades = grades;
+        _docs = docs;
+    }
+
+    public void LoadStudent(Guid studentId)
+    {
+        Student = _students.GetById(studentId);
+        if (Student is null) return;
+
+        StudentTitle = Student.FullName;
+        EditFirstName = Student.FirstName;
+        EditLastName = Student.LastName;
+        EditNotes = Student.Notes ?? "";
+
+        LoadEnrollments();
+        LoadDocs();
+    }
+
+    [RelayCommand]
+    private void SwitchTab(StudentTab tab) => ActiveTab = tab;
+
+    [RelayCommand]
+    private void StartEdit() => IsEditing = true;
+
+    [RelayCommand]
+    private void CancelEdit()
+    {
+        if (Student is null) return;
+        EditFirstName = Student.FirstName;
+        EditLastName = Student.LastName;
+        EditNotes = Student.Notes ?? "";
+        IsEditing = false;
+    }
+
+    [RelayCommand]
+    private void SaveEdit()
+    {
+        if (Student is null) return;
+        Student.FirstName = EditFirstName;
+        Student.LastName = EditLastName;
+        Student.Notes = string.IsNullOrWhiteSpace(EditNotes) ? null : EditNotes;
+        _students.Save(Student);
+        StudentTitle = Student.FullName;
+        IsEditing = false;
+    }
+
+    private void LoadEnrollments()
+    {
+        if (Student is null) return;
+        Enrollments.Clear();
+
+        var enrollments = _enrollments.GetByStudent(Student.Id);
+        var groupIds = enrollments.Select(e => e.GroupId).Distinct();
+        var groupMap = groupIds
+            .Select(id => _groups.GetById(id))
+            .Where(g => g is not null)
+            .ToDictionary(g => g!.Id);
+
+        foreach (var e in enrollments.OrderByDescending(e => e.SchoolYear))
+        {
+            if (!groupMap.TryGetValue(e.GroupId, out var group)) continue;
+            Enrollments.Add(new EnrollmentEntry
+            {
+                SchoolYear = e.SchoolYear,
+                GroupName = group.Name,
+                Subject = group.Subject ?? "",
+            });
+        }
+    }
+
+    private void LoadDocs()
+    {
+        if (Student is null) return;
+        Documentation.Clear();
+
+        foreach (var doc in _docs.GetByStudent(Student.Id))
+        {
+            Documentation.Add(new DocEntry
+            {
+                Date = doc.Date.ToString("dd.MM.yyyy"),
+                Title = doc.Title,
+                TypeLabel = doc.Type switch
+                {
+                    DocumentationType.Conversation => "Gespräch",
+                    DocumentationType.Incident     => "Vorkommnis",
+                    DocumentationType.SupportPlan  => "Förderplan",
+                    DocumentationType.Absence      => "Fehlzeit",
+                    _ => "",
+                },
+                IsConfidential = doc.IsConfidential,
+            });
+        }
+    }
+}
+
+public enum StudentTab { Overview, Grades, Documentation }
+
+public class EnrollmentEntry
+{
+    public string SchoolYear { get; set; } = "";
+    public string GroupName { get; set; } = "";
+    public string Subject { get; set; } = "";
+}
+
+public class GradeEntry
+{
+    public string Date { get; set; } = "";
+    public string Value { get; set; } = "";
+    public string Category { get; set; } = "";
+    public string GroupName { get; set; } = "";
+}
+
+public class DocEntry
+{
+    public string Date { get; set; } = "";
+    public string Title { get; set; } = "";
+    public string TypeLabel { get; set; } = "";
+    public bool IsConfidential { get; set; }
+}
--- a/LehrerApp.Desktop/ViewModels/SyncStatusViewModel.cs
+++ b/LehrerApp.Desktop/ViewModels/SyncStatusViewModel.cs
@@ -0,0 +1,63 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Sync;
+using LehrerApp.Sync.Models;
+
+namespace LehrerApp.Desktop.ViewModels;
+
+public partial class SyncStatusViewModel : ObservableObject
+{
+    private readonly SyncEngine? _engine;
+
+    [ObservableProperty] private string _statusText = "Kein Server konfiguriert";
+    [ObservableProperty] private string _lastSyncText = "";
+    [ObservableProperty] private int _pendingCount;
+    [ObservableProperty] private int _conflictCount;
+    [ObservableProperty] private bool _isSyncing;
+    [ObservableProperty] private bool _hasConflicts;
+    [ObservableProperty] private bool _isServerConfigured;
+
+    public SyncStatusViewModel(SyncEngine? engine)
+    {
+        _engine = engine;
+        IsServerConfigured = engine is not null;
+
+        if (_engine is not null)
+        {
+            _engine.StatusChanged += OnStatusChanged;
+            OnStatusChanged(_engine.Status);
+        }
+    }
+
+    private void OnStatusChanged(SyncStatus status)
+    {
+        IsSyncing    = status.State == SyncState.Syncing;
+        HasConflicts = status.ConflictCount > 0;
+        PendingCount = status.PendingEvents;
+        ConflictCount = status.ConflictCount;
+
+        StatusText = status.State switch
+        {
+            SyncState.Idle    => PendingCount > 0
+                                    ? $"{PendingCount} ausstehend"
+                                    : "Synchronisiert",
+            SyncState.Syncing => "Synchronisiere...",
+            SyncState.Offline => "Offline",
+            SyncState.Error   => $"Fehler: {status.ErrorMessage}",
+            _ => "",
+        };
+
+        LastSyncText = status.LastSyncAt.HasValue
+            ? $"Zuletzt: {status.LastSyncAt:HH:mm}"
+            : "Noch nie synchronisiert";
+    }
+
+    [RelayCommand(CanExecute = nameof(CanSyncNow))]
+    private async Task SyncNow()
+    {
+        if (_engine is null) return;
+        await _engine.SyncNowAsync(isAutomatic: false);
+    }
+
+    private bool CanSyncNow() => _engine is not null && !IsSyncing;
+}
--- a/LehrerApp.Desktop/Views/DashboardView.axaml
+++ b/LehrerApp.Desktop/Views/DashboardView.axaml
@@ -0,0 +1,115 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+             x:Class="LehrerApp.Desktop.Views.DashboardView"
+             x:DataType="vm:DashboardViewModel">
+
+  <ScrollViewer Padding="24">
+    <StackPanel Spacing="20">
+
+      <!-- Header -->
+      <StackPanel>
+        <TextBlock Text="{Binding Greeting}" FontSize="14" Opacity="0.6" />
+        <TextBlock Text="{Binding CurrentDate}" FontSize="24" FontWeight="SemiBold" />
+      </StackPanel>
+
+      <Grid ColumnDefinitions="*,*" RowDefinitions="Auto,Auto" >
+
+        <!-- Heutige Stunden -->
+        <Border Grid.Column="0" Grid.Row="0"
+                Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+                CornerRadius="8" Padding="16" Margin="0,0,8,8">
+          <StackPanel>
+            <TextBlock Text="HEUTE" FontSize="11" FontWeight="Bold"
+                       Opacity="0.5" Margin="0,0,0,12"/>
+            <ItemsControl ItemsSource="{Binding TodaysLessons}">
+              <ItemsControl.ItemTemplate>
+                <DataTemplate DataType="vm:LessonItem">
+                  <Border Padding="0,6" BorderThickness="0,0,0,1"
+                          BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}">
+                    <Grid ColumnDefinitions="Auto,*">
+                      <Border Grid.Column="0" Width="4" CornerRadius="2"
+                              Background="{DynamicResource SystemAccentColor}"
+                              Margin="0,0,10,0"/>
+                      <StackPanel Grid.Column="1">
+                        <TextBlock Text="{Binding GroupName}"
+                                   FontWeight="SemiBold" FontSize="13"/>
+                        <TextBlock Text="{Binding Topic}"
+                                   FontSize="12" Opacity="0.7"
+                                   TextTrimming="CharacterEllipsis"/>
+                      </StackPanel>
+                    </Grid>
+                  </Border>
+                </DataTemplate>
+              </ItemsControl.ItemTemplate>
+            </ItemsControl>
+            <TextBlock Text="Keine Stunden heute" FontSize="13" Opacity="0.5"
+                       IsVisible="{Binding !TodaysLessons.Count}"/>
+          </StackPanel>
+        </Border>
+
+        <!-- Offene Aufgaben -->
+        <Border Grid.Column="1" Grid.Row="0"
+                Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+                CornerRadius="8" Padding="16" Margin="8,0,0,8">
+          <StackPanel>
+            <TextBlock Text="OFFENE AUFGABEN" FontSize="11" FontWeight="Bold"
+                       Opacity="0.5" Margin="0,0,0,12"/>
+            <ItemsControl ItemsSource="{Binding OpenTasks}">
+              <ItemsControl.ItemTemplate>
+                <DataTemplate DataType="vm:TaskItem">
+                  <Grid ColumnDefinitions="*,Auto" Margin="0,4">
+                    <StackPanel Grid.Column="0">
+                      <TextBlock Text="{Binding Title}"
+                                 FontSize="13" TextTrimming="CharacterEllipsis"/>
+                    </StackPanel>
+                    <TextBlock Grid.Column="1" Text="{Binding DueDate}"
+                               FontSize="12" Opacity="0.6" Margin="8,0,0,0"/>
+                  </Grid>
+                </DataTemplate>
+              </ItemsControl.ItemTemplate>
+            </ItemsControl>
+            <TextBlock Text="Keine offenen Aufgaben" FontSize="13" Opacity="0.5"
+                       IsVisible="{Binding !OpenTasks.Count}"/>
+          </StackPanel>
+        </Border>
+
+        <!-- Meine Lerngruppen -->
+        <Border Grid.Column="0" Grid.Row="1" Grid.ColumnSpan="2"
+                Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+                CornerRadius="8" Padding="16">
+          <StackPanel>
+            <TextBlock Text="MEINE LERNGRUPPEN" FontSize="11" FontWeight="Bold"
+                       Opacity="0.5" Margin="0,0,0,12"/>
+            <ItemsControl ItemsSource="{Binding CurrentGroups}">
+              <ItemsControl.ItemsPanel>
+                <ItemsPanelTemplate>
+                  <WrapPanel Orientation="Horizontal"/>
+                </ItemsPanelTemplate>
+              </ItemsControl.ItemsPanel>
+              <ItemsControl.ItemTemplate>
+                <DataTemplate DataType="vm:GroupChip">
+                  <Border Background="{DynamicResource SystemAccentColorLight2}"
+                          CornerRadius="6" Padding="12,6" Margin="0,0,8,8">
+                    <StackPanel>
+                      <TextBlock Text="{Binding Name}"
+                                 FontWeight="SemiBold" FontSize="13"/>
+                      <TextBlock Text="{Binding Subject}"
+                                 FontSize="11" Opacity="0.7"
+                                 IsVisible="{Binding Subject, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+                    </StackPanel>
+                  </Border>
+                </DataTemplate>
+              </ItemsControl.ItemTemplate>
+            </ItemsControl>
+            <TextBlock Text="Noch keine Lerngruppen für dieses Schuljahr"
+                       FontSize="13" Opacity="0.5"
+                       IsVisible="{Binding !CurrentGroups.Count}"/>
+          </StackPanel>
+        </Border>
+
+      </Grid>
+    </StackPanel>
+  </ScrollViewer>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/DataTemplates.axaml
+++ b/LehrerApp.Desktop/Views/DataTemplates.axaml
@@ -0,0 +1,38 @@
+<ResourceDictionary xmlns="https://github.com/avaloniaui"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+                    xmlns:vmg="clr-namespace:LehrerApp.Desktop.ViewModels.Groups"
+                    xmlns:vms="clr-namespace:LehrerApp.Desktop.ViewModels.Students"
+                    xmlns:vg="clr-namespace:LehrerApp.Desktop.Views.Groups"
+                    xmlns:vs="clr-namespace:LehrerApp.Desktop.Views.Students"
+                    xmlns:v="clr-namespace:LehrerApp.Desktop.Views">
+
+  <!-- Dashboard -->
+  <DataTemplate DataType="vm:DashboardViewModel">
+    <v:DashboardView/>
+  </DataTemplate>
+
+  <!-- Platzhalter -->
+  <DataTemplate DataType="vm:PlaceholderViewModel">
+    <v:PlaceholderView/>
+  </DataTemplate>
+
+  <!-- Gruppen -->
+  <DataTemplate DataType="vmg:GroupListViewModel">
+    <vg:GroupListView/>
+  </DataTemplate>
+
+  <DataTemplate DataType="vmg:GroupDetailViewModel">
+    <vg:GroupDetailView/>
+  </DataTemplate>
+
+  <!-- Schüler -->
+  <DataTemplate DataType="vms:StudentListViewModel">
+    <vs:StudentListView/>
+  </DataTemplate>
+
+  <DataTemplate DataType="vms:StudentDetailViewModel">
+    <vs:StudentDetailView/>
+  </DataTemplate>
+
+</ResourceDictionary>
--- a/LehrerApp.Desktop/Views/DevicePairingDialog.axaml
+++ b/LehrerApp.Desktop/Views/DevicePairingDialog.axaml
@@ -0,0 +1,185 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+        x:Class="LehrerApp.Desktop.Views.DevicePairingDialog"
+        x:DataType="vm:DevicePairingViewModel"
+        Title="Gerät einrichten"
+        Width="480" Height="420"
+        CanResize="False"
+        WindowStartupLocation="CenterOwner">
+
+  <Grid Margin="28">
+
+    <!-- ── Modus: Auswahl ──────────────────────────────────────────────────── -->
+    <StackPanel Spacing="16"
+                IsVisible="{Binding Mode,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:PairingMode.SelectMode}}">
+
+      <TextBlock Text="Gerät einrichten"
+                 FontSize="20" FontWeight="SemiBold"/>
+      <TextBlock TextWrapping="Wrap" Opacity="0.7">
+        Möchtest du ein neues Gerät mit deinem bestehenden Datenbestand
+        verbinden, oder dieses Gerät als erstes Gerät einrichten?
+      </TextBlock>
+
+      <Button Content="Daten auf dieses Gerät übertragen"
+              HorizontalAlignment="Stretch"
+              Command="{Binding SelectReceiverCommand}"
+              Padding="12,10"/>
+
+      <Button Content="Von diesem Gerät Daten übertragen"
+              HorizontalAlignment="Stretch"
+              Command="{Binding SelectSenderCommand}"
+              Padding="12,10"/>
+
+    </StackPanel>
+
+    <!-- ── Modus: Sender ───────────────────────────────────────────────────── -->
+    <StackPanel Spacing="16"
+                IsVisible="{Binding Mode,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:PairingMode.Sender}}">
+
+      <TextBlock Text="Daten übertragen"
+                 FontSize="20" FontWeight="SemiBold"/>
+      <TextBlock TextWrapping="Wrap" Opacity="0.7">
+        Es wird ein verschlüsselter Snapshot deiner lokalen Datenbank erstellt
+        und kurzzeitig auf dem Server hinterlegt. Du erhältst einen Einmal-Code
+        der 24 Stunden gültig ist.
+      </TextBlock>
+
+      <!-- Fortschritt -->
+      <ProgressBar Value="{Binding ProgressPercent}"
+                   Maximum="100" Height="6" CornerRadius="3"
+                   IsVisible="{Binding IsBusy}"/>
+      <TextBlock Text="{Binding StatusMessage}"
+                 FontSize="12" Opacity="0.7"
+                 IsVisible="{Binding IsBusy}"/>
+
+      <!-- Fehler -->
+      <Border Background="#22FF0000" CornerRadius="6" Padding="12"
+              IsVisible="{Binding IsError}">
+        <TextBlock Text="{Binding StatusMessage}"
+                   TextWrapping="Wrap" Foreground="Red"/>
+      </Border>
+
+      <Grid ColumnDefinitions="*,8,Auto" Margin="0,8,0,0">
+        <Button Grid.Column="0"
+                Content="← Zurück"
+                Command="{Binding BackCommand}"
+                IsEnabled="{Binding !IsBusy}"/>
+        <Button Grid.Column="2"
+                Content="Snapshot erstellen"
+                Command="{Binding CreateSnapshotCommand}"
+                IsEnabled="{Binding !IsBusy}"
+                Padding="16,8"/>
+      </Grid>
+    </StackPanel>
+
+    <!-- ── Modus: Sender zeigt Code ────────────────────────────────────────── -->
+    <StackPanel Spacing="16"
+                IsVisible="{Binding Mode,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:PairingMode.SenderShowCode}}">
+
+      <TextBlock Text="Code bereit" FontSize="20" FontWeight="SemiBold"/>
+      <TextBlock TextWrapping="Wrap" Opacity="0.7">
+        Gib diesen Code auf dem Zielgerät ein. Der Code ist einmalig verwendbar.
+      </TextBlock>
+
+      <!-- Der Code prominent anzeigen -->
+      <Border Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+              CornerRadius="10" Padding="24,20">
+        <StackPanel HorizontalAlignment="Center" Spacing="8">
+          <TextBlock Text="{Binding GeneratedCode}"
+                     FontSize="32" FontWeight="Bold"
+                     FontFamily="Cascadia Code, Consolas, monospace"
+                     HorizontalAlignment="Center"
+                     LetterSpacing="4"/>
+          <TextBlock Text="{Binding CodeExpiresText}"
+                     FontSize="12" Opacity="0.5"
+                     HorizontalAlignment="Center"/>
+        </StackPanel>
+      </Border>
+
+      <TextBlock TextWrapping="Wrap" FontSize="12" Opacity="0.6">
+        Der Code wird nach dem ersten Abruf automatisch ungültig.
+        Der Server speichert nur verschlüsselte Daten – kein Klartext.
+      </TextBlock>
+
+      <Button Content="Fertig" HorizontalAlignment="Right"
+              Click="OnClose" Padding="16,8"/>
+
+    </StackPanel>
+
+    <!-- ── Modus: Empfänger – Code eingeben ────────────────────────────────── -->
+    <StackPanel Spacing="16"
+                IsVisible="{Binding Mode,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:PairingMode.Receiver}}">
+
+      <TextBlock Text="Code eingeben"
+                 FontSize="20" FontWeight="SemiBold"/>
+      <TextBlock TextWrapping="Wrap" Opacity="0.7">
+        Gib den Code ein der auf dem Quellgerät angezeigt wird.
+        Format: WORT-ZZ-WORT (z.B. TIGER-42-BLAU)
+      </TextBlock>
+
+      <TextBox Text="{Binding InputCode}"
+               Watermark="TIGER-42-BLAU"
+               FontSize="20"
+               FontFamily="Cascadia Code, Consolas, monospace"
+               TextAlignment="Center"
+               CharacterCasing="Upper"/>
+
+      <!-- Fortschritt -->
+      <ProgressBar Value="{Binding ProgressPercent}"
+                   Maximum="100" Height="6" CornerRadius="3"
+                   IsVisible="{Binding IsBusy}"/>
+      <TextBlock Text="{Binding StatusMessage}"
+                 FontSize="12" Opacity="0.7"
+                 IsVisible="{Binding IsBusy}"/>
+
+      <!-- Fehler -->
+      <Border Background="#22FF0000" CornerRadius="6" Padding="12"
+              IsVisible="{Binding IsError}">
+        <TextBlock Text="{Binding StatusMessage}"
+                   TextWrapping="Wrap" Foreground="Red"/>
+      </Border>
+
+      <Grid ColumnDefinitions="*,8,Auto">
+        <Button Grid.Column="0" Content="← Zurück"
+                Command="{Binding BackCommand}"
+                IsEnabled="{Binding !IsBusy}"/>
+        <Button Grid.Column="2"
+                Content="Wiederherstellen"
+                Click="OnRestore"
+                IsEnabled="{Binding !IsBusy}"
+                Padding="16,8"/>
+      </Grid>
+    </StackPanel>
+
+    <!-- ── Modus: Empfänger – Fertig ───────────────────────────────────────── -->
+    <StackPanel Spacing="16" HorizontalAlignment="Center"
+                VerticalAlignment="Center"
+                IsVisible="{Binding Mode,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:PairingMode.ReceiverDone}}">
+
+      <TextBlock Text="✓" FontSize="48" HorizontalAlignment="Center"
+                 Foreground="Green"/>
+      <TextBlock Text="Erfolgreich übertragen!"
+                 FontSize="20" FontWeight="SemiBold"
+                 HorizontalAlignment="Center"/>
+      <TextBlock Text="{Binding StatusMessage}"
+                 Opacity="0.7" HorizontalAlignment="Center"
+                 TextWrapping="Wrap" TextAlignment="Center"/>
+      <Button Content="App neu starten"
+              HorizontalAlignment="Center"
+              Click="OnRestartRequested"
+              Padding="16,8" Margin="0,8,0,0"/>
+    </StackPanel>
+
+  </Grid>
+</Window>
--- a/LehrerApp.Desktop/Views/DevicePairingDialog.axaml.cs
+++ b/LehrerApp.Desktop/Views/DevicePairingDialog.axaml.cs
@@ -0,0 +1,34 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using LehrerApp.Desktop.ViewModels;
+
+namespace LehrerApp.Desktop.Views;
+
+public partial class DevicePairingDialog : Window
+{
+    // Wird von außen gesetzt – Pfad zur lokalen DB
+    public string TargetDbPath { get; set; } = "";
+
+    // Signal: App-Neustart nötig
+    public bool RestartRequested { get; private set; }
+
+    public DevicePairingDialog()
+    {
+        InitializeComponent();
+    }
+
+    private void OnClose(object? sender, RoutedEventArgs e) =>
+        Close();
+
+    private async void OnRestore(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is DevicePairingViewModel vm)
+            await vm.RestoreCommand.ExecuteAsync(TargetDbPath);
+    }
+
+    private void OnRestartRequested(object? sender, RoutedEventArgs e)
+    {
+        RestartRequested = true;
+        Close();
+    }
+}
--- a/LehrerApp.Desktop/Views/Groups/AddGroupDialog.axaml
+++ b/LehrerApp.Desktop/Views/Groups/AddGroupDialog.axaml
@@ -0,0 +1,109 @@
+<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.AddGroupDialog"
+        x:DataType="vm:AddGroupDialogViewModel"
+        Title="Neue Lerngruppe"
+        Width="420" Height="480"
+        CanResize="False"
+        WindowStartupLocation="CenterOwner">
+
+  <Grid RowDefinitions="*,Auto" Margin="24">
+
+    <StackPanel Grid.Row="0" Spacing="16">
+
+      <TextBlock Text="Neue Lerngruppe anlegen"
+                 FontSize="18" FontWeight="SemiBold"/>
+
+      <!-- Name -->
+      <StackPanel Spacing="4">
+        <TextBlock Text="Name *" FontSize="12" Opacity="0.7"/>
+        <TextBox Text="{Binding Name}"
+                 Watermark="z.B. 10E, Q1 Chemie, 5a"/>
+      </StackPanel>
+
+      <!-- Fach -->
+      <StackPanel Spacing="4">
+        <TextBlock Text="Fach" FontSize="12" Opacity="0.7"/>
+        <TextBox Text="{Binding Subject}"
+                 Watermark="z.B. Chemie, Mathematik"/>
+      </StackPanel>
+
+      <!-- Typ und Klassenstufe nebeneinander -->
+      <Grid ColumnDefinitions="*,12,*">
+        <StackPanel Grid.Column="0" Spacing="4">
+          <TextBlock Text="Typ" FontSize="12" Opacity="0.7"/>
+          <ComboBox ItemsSource="{Binding GroupTypes}"
+                    SelectedItem="{Binding Type}"
+                    HorizontalAlignment="Stretch">
+            <ComboBox.ItemTemplate>
+              <DataTemplate DataType="vm:GroupTypeItem">
+                <TextBlock Text="{Binding Label}"/>
+              </DataTemplate>
+            </ComboBox.ItemTemplate>
+          </ComboBox>
+        </StackPanel>
+
+        <StackPanel Grid.Column="2" Spacing="4">
+          <TextBlock Text="Klassenstufe *" FontSize="12" Opacity="0.7"/>
+          <NumericUpDown Value="{Binding GradeLevel}"
+                         Minimum="1" Maximum="13"
+                         FormatString="0"/>
+        </StackPanel>
+      </Grid>
+
+      <!-- Notensystem und Schuljahr -->
+      <Grid ColumnDefinitions="*,12,*">
+        <StackPanel Grid.Column="0" Spacing="4">
+          <TextBlock Text="Notensystem" FontSize="12" Opacity="0.7"/>
+          <ComboBox ItemsSource="{Binding GradingSystems}"
+                    SelectedItem="{Binding GradingSystem}"
+                    HorizontalAlignment="Stretch">
+            <ComboBox.ItemTemplate>
+              <DataTemplate DataType="vm:GradingSystemItem">
+                <TextBlock Text="{Binding Label}" TextWrapping="Wrap"/>
+              </DataTemplate>
+            </ComboBox.ItemTemplate>
+          </ComboBox>
+        </StackPanel>
+
+        <StackPanel Grid.Column="2" Spacing="4">
+          <TextBlock Text="Schuljahr" FontSize="12" Opacity="0.7"/>
+          <ComboBox ItemsSource="{Binding SchoolYears}"
+                    SelectedItem="{Binding SelectedSchoolYear}"
+                    HorizontalAlignment="Stretch"/>
+        </StackPanel>
+      </Grid>
+
+      <!-- Wochenstunden -->
+      <StackPanel Spacing="4">
+        <TextBlock Text="Wochenstunden (optional)" FontSize="12" Opacity="0.7"/>
+        <NumericUpDown Value="{Binding HoursPerWeek}"
+                       Minimum="1" Maximum="20"
+                       FormatString="0"
+                       AllowSpin="True"/>
+      </StackPanel>
+
+      <!-- Validierungsfehler -->
+      <TextBlock Text="{Binding ValidationMessage}"
+                 Foreground="Red" FontSize="12"
+                 IsVisible="{Binding ValidationMessage,
+                   Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+    </StackPanel>
+
+    <!-- ── Buttons ──────────────────────────────────────────────────────── -->
+    <Grid Grid.Row="1" ColumnDefinitions="*,8,*" Margin="0,16,0,0">
+      <Button Grid.Column="0"
+              Content="Abbrechen"
+              HorizontalAlignment="Stretch"
+              Click="OnCancel"/>
+      <Button Grid.Column="2"
+              Content="Anlegen"
+              HorizontalAlignment="Stretch"
+              Click="OnSave"/>
+    </Grid>
+
+  </Grid>
+
+</Window>
--- a/LehrerApp.Desktop/Views/Groups/AddGroupDialog.axaml.cs
+++ b/LehrerApp.Desktop/Views/Groups/AddGroupDialog.axaml.cs
@@ -0,0 +1,33 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+
+namespace LehrerApp.Desktop.Views.Groups;
+
+public partial class AddGroupDialog : Window
+{
+    public bool Saved { get; private set; }
+
+    public AddGroupDialog()
+    {
+        InitializeComponent();
+    }
+
+    private void OnSave(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is ViewModels.Groups.AddGroupDialogViewModel vm)
+        {
+            if (vm.SaveCommand.CanExecute(null))
+            {
+                vm.SaveCommand.Execute(null);
+                if (vm.Result is not null)
+                {
+                    Saved = true;
+                    Close(true);
+                }
+            }
+        }
+    }
+
+    private void OnCancel(object? sender, RoutedEventArgs e) =>
+        Close(false);
+}
--- a/LehrerApp.Desktop/Views/Groups/GroupDetailView.axaml
+++ b/LehrerApp.Desktop/Views/Groups/GroupDetailView.axaml
@@ -0,0 +1,129 @@
+<UserControl 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.GroupDetailView"
+             x:DataType="vm:GroupDetailViewModel">
+
+  <Grid RowDefinitions="Auto,Auto,*">
+
+    <!-- ── Header ──────────────────────────────────────────────────────── -->
+    <Border Grid.Row="0" Padding="20,16"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1">
+      <Grid ColumnDefinitions="*,Auto">
+        <StackPanel Grid.Column="0">
+          <TextBlock Text="{Binding GroupTitle}"
+                     FontSize="22" FontWeight="SemiBold"/>
+          <TextBlock FontSize="12" Opacity="0.5">
+            <Run Text="{Binding StudentCount}"/>
+            <Run Text="Schüler"/>
+          </TextBlock>
+        </StackPanel>
+        <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="8">
+          <Button Content="+ Schüler"
+                  Command="{Binding AddStudentCommand}"/>
+          <Button Content="+ Klausur"
+                  Command="{Binding AddExamCommand}"/>
+        </StackPanel>
+      </Grid>
+    </Border>
+
+    <!-- ── Tab-Leiste ──────────────────────────────────────────────────── -->
+    <Border Grid.Row="1"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1"
+            Padding="16,0">
+      <StackPanel Orientation="Horizontal" Spacing="4">
+        <Button Content="Übersicht"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:GroupTab.Overview}"
+                Classes.active="{Binding ActiveTab,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:GroupTab.Overview}}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Schüler"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:GroupTab.Students}"
+                Classes.active="{Binding ActiveTab,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:GroupTab.Students}}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Klausuren"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:GroupTab.Exams}"
+                Classes.active="{Binding ActiveTab,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:GroupTab.Exams}}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Noten"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:GroupTab.Grades}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Planung"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:GroupTab.Planner}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Dokumentation"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:GroupTab.Documentation}"
+                Background="Transparent" Padding="12,8"/>
+      </StackPanel>
+    </Border>
+
+    <!-- ── Tab-Inhalt ──────────────────────────────────────────────────── -->
+    <ScrollViewer Grid.Row="2" Padding="20">
+
+      <!-- Schülerliste -->
+      <DataGrid ItemsSource="{Binding Students}"
+                IsVisible="{Binding ActiveTab,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:GroupTab.Students}}"
+                AutoGenerateColumns="False"
+                IsReadOnly="True"
+                GridLinesVisibility="Horizontal"
+                CanUserReorderColumns="False"
+                CanUserResizeColumns="True">
+        <DataGrid.Columns>
+          <DataGridTextColumn Header="Name"
+                              Binding="{Binding FullName}"
+                              Width="*"/>
+        </DataGrid.Columns>
+      </DataGrid>
+
+      <!-- Klausuren -->
+      <DataGrid ItemsSource="{Binding Exams}"
+                IsVisible="{Binding ActiveTab,
+                  Converter={x:Static ObjectConverters.Equal},
+                  ConverterParameter={x:Static vm:GroupTab.Exams}}"
+                AutoGenerateColumns="False"
+                IsReadOnly="True"
+                GridLinesVisibility="Horizontal"
+                CanUserReorderColumns="False">
+        <DataGrid.Columns>
+          <DataGridTextColumn Header="Datum"
+                              Binding="{Binding Date}"
+                              Width="100"/>
+          <DataGridTextColumn Header="Titel"
+                              Binding="{Binding Title}"
+                              Width="*"/>
+          <DataGridTextColumn Header="Status"
+                              Binding="{Binding Status}"
+                              Width="120"/>
+        </DataGrid.Columns>
+      </DataGrid>
+
+      <!-- Übersicht (Platzhalter) -->
+      <StackPanel IsVisible="{Binding ActiveTab,
+                    Converter={x:Static ObjectConverters.Equal},
+                    ConverterParameter={x:Static vm:GroupTab.Overview}}"
+                  Spacing="12">
+        <TextBlock Text="Übersicht" FontSize="16" FontWeight="SemiBold"/>
+        <TextBlock Text="Hier erscheint eine Zusammenfassung der Lerngruppe."
+                   Opacity="0.5"/>
+      </StackPanel>
+
+    </ScrollViewer>
+
+  </Grid>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/Groups/GroupListView.axaml
+++ b/LehrerApp.Desktop/Views/Groups/GroupListView.axaml
@@ -0,0 +1,100 @@
+<UserControl 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.GroupListView"
+             x:DataType="vm:GroupListViewModel">
+
+  <Grid RowDefinitions="Auto,*">
+
+    <!-- ── Toolbar ─────────────────────────────────────────────────────── -->
+    <Border Grid.Row="0" Padding="20,16"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1">
+      <Grid ColumnDefinitions="*,Auto,Auto">
+
+        <StackPanel Grid.Column="0">
+          <TextBlock Text="Lerngruppen" FontSize="22" FontWeight="SemiBold"/>
+          <TextBlock FontSize="12" Opacity="0.5">
+            <Run Text="{Binding Groups.Count}"/>
+            <Run Text="Gruppen ·"/>
+            <Run Text="{Binding SelectedSchoolYear}"/>
+          </TextBlock>
+        </StackPanel>
+
+        <!-- Schuljahr-Auswahl -->
+        <ComboBox Grid.Column="1"
+                  ItemsSource="{Binding SchoolYears}"
+                  SelectedItem="{Binding SelectedSchoolYear}"
+                  Width="100" Margin="0,0,8,0"
+                  VerticalAlignment="Center"/>
+
+        <!-- Neue Gruppe -->
+        <Button Grid.Column="2"
+                Content="+ Neue Gruppe"
+                Command="{Binding AddGroupCommand}"
+                VerticalAlignment="Center"/>
+      </Grid>
+    </Border>
+
+    <!-- ── Inhalt ──────────────────────────────────────────────────────── -->
+    <Grid Grid.Row="1" ColumnDefinitions="260,*">
+
+      <!-- Suchliste links -->
+      <Border Grid.Column="0"
+              BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+              BorderThickness="0,0,1,0">
+        <DockPanel>
+          <TextBox DockPanel.Dock="Top"
+                   Text="{Binding SearchText}"
+                   Watermark="Suchen…"
+                   Margin="12,8"/>
+          <ListBox ItemsSource="{Binding Groups}"
+                   SelectedItem="{Binding SelectedGroup}">
+            <ListBox.ItemTemplate>
+              <DataTemplate DataType="vm:GroupListItem">
+                <Grid ColumnDefinitions="4,*" Margin="0,4">
+                  <Border Grid.Column="0" Width="4" CornerRadius="2"
+                          Background="{DynamicResource SystemAccentColor}"
+                          Margin="0,0,10,0"/>
+                  <StackPanel Grid.Column="1">
+                    <Grid ColumnDefinitions="*,Auto">
+                      <TextBlock Grid.Column="0"
+                                 Text="{Binding Name}"
+                                 FontWeight="SemiBold" FontSize="13"/>
+                      <TextBlock Grid.Column="1"
+                                 Text="{Binding TypeLabel}"
+                                 FontSize="11" Opacity="0.5"/>
+                    </Grid>
+                    <TextBlock Text="{Binding Subject}"
+                               FontSize="12" Opacity="0.65"
+                               IsVisible="{Binding Subject,
+                                 Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+                    <TextBlock Text="{Binding GradingLabel}"
+                               FontSize="11" Opacity="0.4"/>
+                  </StackPanel>
+                </Grid>
+              </DataTemplate>
+            </ListBox.ItemTemplate>
+          </ListBox>
+        </DockPanel>
+      </Border>
+
+      <!-- Detail rechts – Platzhalter bis Gruppe gewählt -->
+      <Border Grid.Column="1">
+        <StackPanel HorizontalAlignment="Center"
+                    VerticalAlignment="Center"
+                    Spacing="8"
+                    IsVisible="{Binding !SelectedGroup}">
+          <TextBlock Text="Keine Gruppe ausgewählt"
+                     FontSize="16" Opacity="0.4"
+                     HorizontalAlignment="Center"/>
+          <TextBlock Text="Wähle eine Gruppe aus der Liste oder lege eine neue an."
+                     FontSize="12" Opacity="0.3"
+                     HorizontalAlignment="Center"/>
+        </StackPanel>
+      </Border>
+
+    </Grid>
+  </Grid>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/Groups/GroupViews.cs
+++ b/LehrerApp.Desktop/Views/Groups/GroupViews.cs
@@ -0,0 +1,13 @@
+using Avalonia.Controls;
+
+namespace LehrerApp.Desktop.Views.Groups;
+
+public partial class GroupListView : UserControl
+{
+    public GroupListView() => InitializeComponent();
+}
+
+public partial class GroupDetailView : UserControl
+{
+    public GroupDetailView() => InitializeComponent();
+}
--- a/LehrerApp.Desktop/Views/MainWindow.axaml
+++ b/LehrerApp.Desktop/Views/MainWindow.axaml
@@ -0,0 +1,108 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+        xmlns:views="clr-namespace:LehrerApp.Desktop.Views"
+        x:Class="LehrerApp.Desktop.Views.MainWindow"
+        x:DataType="vm:MainWindowViewModel"
+        Title="LehrerApp"
+        Width="1280" Height="800"
+        MinWidth="900" MinHeight="600">
+
+  <Grid ColumnDefinitions="220,*">
+
+    <!-- ── Sidebar ───────────────────────────────────────────────────────── -->
+    <Border Grid.Column="0"
+            Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,1,0">
+
+      <DockPanel>
+
+        <!-- Header -->
+        <Border DockPanel.Dock="Top" Padding="16,20,16,12"
+                BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+                BorderThickness="0,0,0,1">
+          <StackPanel>
+            <TextBlock Text="LehrerApp"
+                       FontSize="20" FontWeight="SemiBold" />
+            <TextBlock Text="{Binding CurrentSchoolYear, FallbackValue=''}"
+                       FontSize="12" Opacity="0.6" Margin="0,2,0,0"/>
+          </StackPanel>
+        </Border>
+
+        <!-- Sync-Status unten -->
+        <Border DockPanel.Dock="Bottom" Padding="12,8"
+                BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+                BorderThickness="0,1,0,0">
+          <views:SyncStatusBar />
+        </Border>
+
+        <!-- Nav-Items -->
+        <StackPanel Margin="8,12">
+          <views:NavButton Icon="&#xE80F;" Label="Dashboard"
+                           Item="Dashboard"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Dashboard}" />
+
+          <TextBlock Text="UNTERRICHT" FontSize="10" FontWeight="Bold"
+                     Opacity="0.4" Margin="8,16,0,4" />
+
+          <views:NavButton Icon="&#xE8F1;" Label="Lerngruppen"
+                           Item="Groups"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Groups}" />
+
+          <views:NavButton Icon="&#xE77B;" Label="Schüler"
+                           Item="Students"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Students}" />
+
+          <views:NavButton Icon="&#xE943;" Label="Klausuren"
+                           Item="Exams"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Exams}" />
+
+          <views:NavButton Icon="&#xE70B;" Label="Planung"
+                           Item="Planner"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Planner}" />
+
+          <TextBlock Text="VERWALTUNG" FontSize="10" FontWeight="Bold"
+                     Opacity="0.4" Margin="8,16,0,4" />
+
+          <views:NavButton Icon="&#xE823;" Label="Arbeitszeit"
+                           Item="Workload"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Workload}" />
+
+          <views:NavButton Icon="&#xE713;" Label="Einstellungen"
+                           Item="Settings"
+                           ActiveItem="{Binding ActiveNavItem}"
+                           Command="{Binding NavigateToCommand}"
+                           CommandParameter="{x:Static vm:NavItem.Settings}" />
+        </StackPanel>
+
+      </DockPanel>
+    </Border>
+
+    <!-- ── Hauptinhalt ───────────────────────────────────────────────────── -->
+    <ContentControl Grid.Column="1"
+                    Content="{Binding CurrentPage}">
+      <ContentControl.DataTemplates>
+        <DataTemplate DataType="vm:DashboardViewModel">
+          <views:DashboardView />
+        </DataTemplate>
+        <DataTemplate DataType="{x:Type vm:PlaceholderViewModel}">
+          <views:PlaceholderView />
+        </DataTemplate>
+      </ContentControl.DataTemplates>
+    </ContentControl>
+
+  </Grid>
+</Window>
--- a/LehrerApp.Desktop/Views/MainWindow.axaml.cs
+++ b/LehrerApp.Desktop/Views/MainWindow.axaml.cs
@@ -0,0 +1,11 @@
+using Avalonia.Controls;
+
+namespace LehrerApp.Desktop.Views;
+
+public partial class MainWindow : Window
+{
+    public MainWindow()
+    {
+        InitializeComponent();
+    }
+}
--- a/LehrerApp.Desktop/Views/NavButton.axaml
+++ b/LehrerApp.Desktop/Views/NavButton.axaml
@@ -0,0 +1,38 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+             x:Class="LehrerApp.Desktop.Views.NavButton">
+
+  <Button Command="{Binding Command, RelativeSource={RelativeSource AncestorType=UserControl}}"
+          CommandParameter="{Binding CommandParameter, RelativeSource={RelativeSource AncestorType=UserControl}}"
+          HorizontalAlignment="Stretch"
+          HorizontalContentAlignment="Left"
+          Padding="10,8"
+          CornerRadius="6"
+          Background="Transparent">
+
+    <Grid ColumnDefinitions="24,*">
+      <TextBlock Grid.Column="0"
+                 Text="{Binding Icon, RelativeSource={RelativeSource AncestorType=UserControl}}"
+                 FontFamily="Segoe MDL2 Assets"
+                 FontSize="14"
+                 VerticalAlignment="Center"
+                 HorizontalAlignment="Center"
+                 Opacity="0.7"/>
+      <TextBlock Grid.Column="1"
+                 Text="{Binding Label, RelativeSource={RelativeSource AncestorType=UserControl}}"
+                 FontSize="13"
+                 VerticalAlignment="Center"
+                 Margin="8,0,0,0"/>
+    </Grid>
+
+    <Button.Styles>
+      <Style Selector="Button:pointerover /template/ ContentPresenter">
+        <Setter Property="Background"
+                Value="{DynamicResource SystemControlBackgroundListLowBrush}"/>
+      </Style>
+    </Button.Styles>
+
+  </Button>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/NavButton.axaml.cs
+++ b/LehrerApp.Desktop/Views/NavButton.axaml.cs
@@ -0,0 +1,69 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Input;
+using System.Windows.Input;
+using LehrerApp.Desktop.ViewModels;
+
+namespace LehrerApp.Desktop.Views;
+
+public partial class NavButton : UserControl
+{
+    public static readonly StyledProperty<string> IconProperty =
+        AvaloniaProperty.Register<NavButton, string>(nameof(Icon), "");
+
+    public static readonly StyledProperty<string> LabelProperty =
+        AvaloniaProperty.Register<NavButton, string>(nameof(Label), "");
+
+    public static readonly StyledProperty<NavItem> ItemProperty =
+        AvaloniaProperty.Register<NavButton, NavItem>(nameof(Item));
+
+    public static readonly StyledProperty<NavItem> ActiveItemProperty =
+        AvaloniaProperty.Register<NavButton, NavItem>(nameof(ActiveItem));
+
+    public static readonly StyledProperty<ICommand?> CommandProperty =
+        AvaloniaProperty.Register<NavButton, ICommand?>(nameof(Command));
+
+    public static readonly StyledProperty<object?> CommandParameterProperty =
+        AvaloniaProperty.Register<NavButton, object?>(nameof(CommandParameter));
+
+    public string Icon
+    {
+        get => GetValue(IconProperty);
+        set => SetValue(IconProperty, value);
+    }
+
+    public string Label
+    {
+        get => GetValue(LabelProperty);
+        set => SetValue(LabelProperty, value);
+    }
+
+    public NavItem Item
+    {
+        get => GetValue(ItemProperty);
+        set => SetValue(ItemProperty, value);
+    }
+
+    public NavItem ActiveItem
+    {
+        get => GetValue(ActiveItemProperty);
+        set => SetValue(ActiveItemProperty, value);
+    }
+
+    public ICommand? Command
+    {
+        get => GetValue(CommandProperty);
+        set => SetValue(CommandProperty, value);
+    }
+
+    public object? CommandParameter
+    {
+        get => GetValue(CommandParameterProperty);
+        set => SetValue(CommandParameterProperty, value);
+    }
+
+    public NavButton()
+    {
+        InitializeComponent();
+    }
+}
--- a/LehrerApp.Desktop/Views/PlaceholderView.axaml
+++ b/LehrerApp.Desktop/Views/PlaceholderView.axaml
@@ -0,0 +1,13 @@
+<!-- PlaceholderView.axaml -->
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+             x:Class="LehrerApp.Desktop.Views.PlaceholderView"
+             x:DataType="vm:PlaceholderViewModel">
+  <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Spacing="8">
+    <TextBlock Text="{Binding Title}" FontSize="24" FontWeight="SemiBold"
+               HorizontalAlignment="Center"/>
+    <TextBlock Text="Wird noch implementiert…" Opacity="0.5"
+               HorizontalAlignment="Center"/>
+  </StackPanel>
+</UserControl>
--- a/LehrerApp.Desktop/Views/Students/StudentDetailView.axaml
+++ b/LehrerApp.Desktop/Views/Students/StudentDetailView.axaml
@@ -0,0 +1,148 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Students"
+             x:Class="LehrerApp.Desktop.Views.Students.StudentDetailView"
+             x:DataType="vm:StudentDetailViewModel">
+
+  <Grid RowDefinitions="Auto,Auto,*">
+
+    <!-- ── Header ──────────────────────────────────────────────────────── -->
+    <Border Grid.Row="0" Padding="20,16"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1">
+      <Grid ColumnDefinitions="*,Auto">
+
+        <!-- Anzeigemodus -->
+        <StackPanel Grid.Column="0"
+                    IsVisible="{Binding !IsEditing}">
+          <TextBlock Text="{Binding StudentTitle}"
+                     FontSize="22" FontWeight="SemiBold"/>
+          <TextBlock Text="{Binding Student.DateOfBirth,
+                       StringFormat='Geb. {0:dd.MM.yyyy}',
+                       FallbackValue=''}"
+                     FontSize="12" Opacity="0.5"/>
+        </StackPanel>
+
+        <!-- Bearbeitungsmodus -->
+        <StackPanel Grid.Column="0" Spacing="6"
+                    IsVisible="{Binding IsEditing}">
+          <Grid ColumnDefinitions="*,8,*">
+            <TextBox Grid.Column="0"
+                     Text="{Binding EditFirstName}"
+                     Watermark="Vorname"/>
+            <TextBox Grid.Column="2"
+                     Text="{Binding EditLastName}"
+                     Watermark="Nachname"/>
+          </Grid>
+          <TextBox Text="{Binding EditNotes}"
+                   Watermark="Interne Notiz (optional)"
+                   AcceptsReturn="True" MaxHeight="80"/>
+        </StackPanel>
+
+        <!-- Aktions-Buttons -->
+        <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="8"
+                    VerticalAlignment="Top">
+          <Button Content="Bearbeiten"
+                  Command="{Binding StartEditCommand}"
+                  IsVisible="{Binding !IsEditing}"/>
+          <Button Content="Speichern"
+                  Command="{Binding SaveEditCommand}"
+                  IsVisible="{Binding IsEditing}"/>
+          <Button Content="Abbrechen"
+                  Command="{Binding CancelEditCommand}"
+                  IsVisible="{Binding IsEditing}"/>
+        </StackPanel>
+      </Grid>
+    </Border>
+
+    <!-- ── Tab-Leiste ──────────────────────────────────────────────────── -->
+    <Border Grid.Row="1"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1" Padding="16,0">
+      <StackPanel Orientation="Horizontal" Spacing="4">
+        <Button Content="Übersicht"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:StudentTab.Overview}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Noten"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:StudentTab.Grades}"
+                Background="Transparent" Padding="12,8"/>
+        <Button Content="Dokumentation"
+                Command="{Binding SwitchTabCommand}"
+                CommandParameter="{x:Static vm:StudentTab.Documentation}"
+                Background="Transparent" Padding="12,8"/>
+      </StackPanel>
+    </Border>
+
+    <!-- ── Tab-Inhalt ──────────────────────────────────────────────────── -->
+    <ScrollViewer Grid.Row="2" Padding="20">
+
+      <!-- Übersicht: Lerngruppen-Verlauf -->
+      <StackPanel IsVisible="{Binding ActiveTab,
+                    Converter={x:Static ObjectConverters.Equal},
+                    ConverterParameter={x:Static vm:StudentTab.Overview}}"
+                  Spacing="16">
+
+        <TextBlock Text="Lerngruppen" FontSize="15" FontWeight="SemiBold"/>
+        <ItemsControl ItemsSource="{Binding Enrollments}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate DataType="vm:EnrollmentEntry">
+              <Border Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+                      CornerRadius="6" Padding="12,8" Margin="0,0,0,6">
+                <Grid ColumnDefinitions="Auto,*,Auto">
+                  <TextBlock Grid.Column="0"
+                             Text="{Binding SchoolYear}"
+                             FontWeight="SemiBold" Width="70"/>
+                  <TextBlock Grid.Column="1"
+                             Text="{Binding GroupName}"
+                             Margin="8,0"/>
+                  <TextBlock Grid.Column="2"
+                             Text="{Binding Subject}"
+                             Opacity="0.5" FontSize="12"/>
+                </Grid>
+              </Border>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+
+        <TextBlock Text="{Binding Student.Notes}"
+                   IsVisible="{Binding Student.Notes,
+                     Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
+                   Opacity="0.7" FontSize="13"
+                   TextWrapping="Wrap"/>
+      </StackPanel>
+
+      <!-- Dokumentation -->
+      <ItemsControl IsVisible="{Binding ActiveTab,
+                      Converter={x:Static ObjectConverters.Equal},
+                      ConverterParameter={x:Static vm:StudentTab.Documentation}}"
+                    ItemsSource="{Binding Documentation}">
+        <ItemsControl.ItemTemplate>
+          <DataTemplate DataType="vm:DocEntry">
+            <Border Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+                    CornerRadius="6" Padding="12,10" Margin="0,0,0,8">
+              <Grid ColumnDefinitions="Auto,*,Auto">
+                <TextBlock Grid.Column="0"
+                           Text="{Binding Date}"
+                           Opacity="0.5" FontSize="12" Width="80"/>
+                <StackPanel Grid.Column="1" Margin="8,0">
+                  <TextBlock Text="{Binding Title}"
+                             FontWeight="SemiBold" FontSize="13"/>
+                  <TextBlock Text="{Binding TypeLabel}"
+                             FontSize="11" Opacity="0.5"/>
+                </StackPanel>
+                <TextBlock Grid.Column="2"
+                           Text="🔒" FontSize="14"
+                           IsVisible="{Binding IsConfidential}"
+                           ToolTip.Tip="Vertraulich"/>
+              </Grid>
+            </Border>
+          </DataTemplate>
+        </ItemsControl.ItemTemplate>
+      </ItemsControl>
+
+    </ScrollViewer>
+  </Grid>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/Students/StudentListView.axaml
+++ b/LehrerApp.Desktop/Views/Students/StudentListView.axaml
@@ -0,0 +1,63 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Students"
+             x:Class="LehrerApp.Desktop.Views.Students.StudentListView"
+             x:DataType="vm:StudentListViewModel">
+
+  <Grid RowDefinitions="Auto,*">
+
+    <!-- ── Toolbar ─────────────────────────────────────────────────────── -->
+    <Border Grid.Row="0" Padding="20,16"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1">
+      <Grid ColumnDefinitions="*,Auto,Auto">
+        <StackPanel Grid.Column="0">
+          <TextBlock Text="Schüler" FontSize="22" FontWeight="SemiBold"/>
+          <TextBlock FontSize="12" Opacity="0.5">
+            <Run Text="{Binding Students.Count}"/>
+            <Run Text="Schüler gesamt"/>
+          </TextBlock>
+        </StackPanel>
+
+        <CheckBox Grid.Column="1"
+                  Content="Inaktive anzeigen"
+                  IsChecked="{Binding ShowInactive}"
+                  VerticalAlignment="Center"
+                  Margin="0,0,12,0"/>
+
+        <Button Grid.Column="2"
+                Content="+ Neuer Schüler"
+                Command="{Binding AddStudentCommand}"
+                VerticalAlignment="Center"/>
+      </Grid>
+    </Border>
+
+    <!-- ── Liste + Suche ───────────────────────────────────────────────── -->
+    <DockPanel Grid.Row="1">
+      <TextBox DockPanel.Dock="Top"
+               Text="{Binding SearchText}"
+               Watermark="Name suchen…"
+               Margin="16,10,16,4"/>
+
+      <DataGrid ItemsSource="{Binding Students}"
+                SelectedItem="{Binding SelectedStudent}"
+                AutoGenerateColumns="False"
+                IsReadOnly="True"
+                GridLinesVisibility="Horizontal"
+                CanUserReorderColumns="False"
+                CanUserResizeColumns="True"
+                Margin="16,4">
+        <DataGrid.Columns>
+          <DataGridTextColumn Header="Name"
+                              Binding="{Binding FullName}"
+                              Width="*"/>
+          <DataGridTextColumn Header="Geburtsdatum"
+                              Binding="{Binding DateOfBirth}"
+                              Width="130"/>
+        </DataGrid.Columns>
+      </DataGrid>
+    </DockPanel>
+
+  </Grid>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/Students/StudentViews.cs
+++ b/LehrerApp.Desktop/Views/Students/StudentViews.cs
@@ -0,0 +1,13 @@
+using Avalonia.Controls;
+
+namespace LehrerApp.Desktop.Views.Students;
+
+public partial class StudentListView : UserControl
+{
+    public StudentListView() => InitializeComponent();
+}
+
+public partial class StudentDetailView : UserControl
+{
+    public StudentDetailView() => InitializeComponent();
+}
--- a/LehrerApp.Desktop/Views/SyncStatusBar.axaml
+++ b/LehrerApp.Desktop/Views/SyncStatusBar.axaml
@@ -0,0 +1,24 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+             x:Class="LehrerApp.Desktop.Views.SyncStatusBar"
+             x:DataType="vm:SyncStatusViewModel">
+
+  <Grid ColumnDefinitions="*,Auto">
+    <StackPanel Grid.Column="0">
+      <TextBlock Text="{Binding StatusText}" FontSize="12"
+                 Opacity="0.7" TextTrimming="CharacterEllipsis"/>
+      <TextBlock Text="{Binding LastSyncText}" FontSize="10"
+                 Opacity="0.4"/>
+    </StackPanel>
+    <Button Grid.Column="1"
+            Command="{Binding SyncNowCommand}"
+            IsVisible="{Binding IsServerConfigured}"
+            ToolTip.Tip="Jetzt synchronisieren"
+            Padding="6,4">
+      <TextBlock Text="↻" FontSize="14"
+                 IsVisible="{Binding !IsSyncing}"/>
+    </Button>
+  </Grid>
+
+</UserControl>
--- a/LehrerApp.Desktop/Views/SyncStatusBar.axaml.cs
+++ b/LehrerApp.Desktop/Views/SyncStatusBar.axaml.cs
@@ -0,0 +1,20 @@
+using Avalonia.Controls;
+using LehrerApp.Desktop.ViewModels;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LehrerApp.Desktop.Views;
+
+public partial class SyncStatusBar : UserControl
+{
+    public SyncStatusBar()
+    {
+        InitializeComponent();
+
+        // DataContext aus DI holen sobald die View geladen ist
+        Loaded += (_, _) =>
+        {
+            if (DataContext is null)
+                DataContext = App.Services.GetRequiredService<SyncStatusViewModel>();
+        };
+    }
+}
--- a/LehrerApp.Desktop/Views/ViewCodeBehind.cs
+++ b/LehrerApp.Desktop/Views/ViewCodeBehind.cs
@@ -0,0 +1,17 @@
+using Avalonia.Controls;
+
+namespace LehrerApp.Desktop.Views;
+
+// Code-behind Stubs für Views ohne eigene .axaml.cs
+// NavButton      → eigene NavButton.axaml.cs
+// SyncStatusBar  → eigene SyncStatusBar.axaml.cs
+
+public partial class DashboardView : UserControl
+{
+    public DashboardView() => InitializeComponent();
+}
+
+public partial class PlaceholderView : UserControl
+{
+    public PlaceholderView() => InitializeComponent();
+}
--- a/LehrerApp.Desktop/app.manifest
+++ b/LehrerApp.Desktop/app.manifest
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity version="1.0.0.0" name="LehrerApp.Desktop"/>
+  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v2">
+    <security>
+      <requestedPrivileges xmlns="urn:schemas-microsoft-com:asm.v3">
+        <requestedExecutionLevel level="asInvoker" uiAccess="false"/>
+      </requestedPrivileges>
+    </security>
+  </trustInfo>
+</assembly>