Arbeitszeit: Aufgabenverwaltung (Kapitel 6.1)

Navigationspunkt "Arbeitszeit" zeigt jetzt eine echte Aufgabenliste statt eines
Placeholders: Filter nach Status/Kategorie/Gruppe (Standard blendet Erledigtes aus),
Sortierung nach Fälligkeit, Anlegen/Bearbeiten-Dialog, Status per Klick durchschalten.

LehrerApp.Desktop.Tests/Fakes.cs

@@ -270,6 +270,16 @@ public class FakeSubstitutionEntries : ISubstitutionEntryRepository
     public void Delete(Guid id) => _all.RemoveAll(e => e.Id == id);
 }
 
+public class FakeWorkTasks : IWorkTaskRepository
+{
+    private readonly List<WorkTask> _all = [];
+    public void Add(WorkTask t) => _all.Add(t);
+    public List<WorkTask> GetByStatus(WorkTaskStatus status) => _all.Where(t => t.Status == status).ToList();
+    public List<WorkTask> GetAll() => _all.ToList();
+    public void Save(WorkTask task) { _all.RemoveAll(t => t.Id == task.Id); _all.Add(task); }
+    public void Delete(Guid id) => _all.RemoveAll(t => t.Id == id);
+}
+
 public class FakeReportGrades : IReportGradeRepository
 {
     private readonly List<ReportGrade> _all = [];

LehrerApp.Desktop.Tests/WorkloadViewModelTests.cs

@@ -0,0 +1,195 @@
+using LehrerApp.Core.Models;
+using LehrerApp.Desktop.ViewModels.Workload;
+using Xunit;
+
+namespace LehrerApp.Desktop.Tests;
+
+public sealed class WorkTaskListViewModelTests
+{
+    [Fact]
+    public void Load_BlendetErledigteAufgabenStandardmaessigAus()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "Offen", Status = WorkTaskStatus.Open });
+        tasks.Add(new WorkTask { Title = "Erledigt", Status = WorkTaskStatus.Done });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]));
+
+        Assert.Single(vm.Tasks);
+        Assert.Equal("Offen", vm.Tasks[0].Title);
+    }
+
+    [Fact]
+    public void StatusFilter_Alle_ZeigtAuchErledigteAufgaben()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "Erledigt", Status = WorkTaskStatus.Done });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]))
+        {
+            StatusFilter = WorkTaskListViewModel.AllFilter,
+        };
+
+        Assert.Single(vm.Tasks);
+    }
+
+    [Fact]
+    public void CategoryFilter_FiltertNachKategorie()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "Korrektur", Category = TaskCategory.Correction });
+        tasks.Add(new WorkTask { Title = "Vorbereitung", Category = TaskCategory.Preparation });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]))
+        {
+            CategoryFilter = TaskCategoryDisplay.Label(TaskCategory.Correction),
+        };
+
+        Assert.Single(vm.Tasks);
+        Assert.Equal("Korrektur", vm.Tasks[0].Title);
+    }
+
+    [Fact]
+    public void GroupFilter_OhneGruppe_ZeigtNurAufgabenOhneGroupId()
+    {
+        var group = new LearningGroup { Name = "8a" };
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "Mit Gruppe", GroupId = group.Id });
+        tasks.Add(new WorkTask { Title = "Ohne Gruppe", GroupId = null });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([group]))
+        {
+            GroupFilter = WorkTaskListViewModel.NoGroupFilter,
+        };
+
+        Assert.Single(vm.Tasks);
+        Assert.Equal("Ohne Gruppe", vm.Tasks[0].Title);
+    }
+
+    [Fact]
+    public void CycleStatus_WechseltVonOffenNachInBearbeitung()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "T", Status = WorkTaskStatus.Open });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]))
+        {
+            StatusFilter = WorkTaskListViewModel.AllFilter,
+        };
+
+        vm.CycleStatusCommand.Execute(vm.Tasks[0]);
+
+        Assert.Equal(WorkTaskStatus.InProgress, vm.Tasks[0].Model.Status);
+    }
+
+    [Fact]
+    public void CycleStatus_VonErledigtSpringtZurueckZuOffen()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "T", Status = WorkTaskStatus.Done });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]))
+        {
+            StatusFilter = WorkTaskListViewModel.AllFilter,
+        };
+
+        vm.CycleStatusCommand.Execute(vm.Tasks[0]);
+
+        Assert.Equal(WorkTaskStatus.Open, vm.Tasks[0].Model.Status);
+    }
+
+    [Fact]
+    public void DeleteTask_EntferntAufgabeAusDerListe()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "T" });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]));
+
+        vm.DeleteTaskCommand.Execute(vm.Tasks[0]);
+
+        Assert.Empty(vm.Tasks);
+    }
+
+    [Fact]
+    public async Task AddTask_RuftOnEditTaskAufUndSpeichertErgebnis()
+    {
+        var tasks = new FakeWorkTasks();
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]));
+        vm.OnEditTask = _ => Task.FromResult<WorkTask?>(new WorkTask { Title = "Neu" });
+
+        await vm.AddTaskCommand.ExecuteAsync(null);
+
+        Assert.Single(vm.Tasks);
+        Assert.Equal("Neu", vm.Tasks[0].Title);
+    }
+
+    [Fact]
+    public void Tasks_SindNachFaelligkeitSortiertUnbefristeteAmEnde()
+    {
+        var tasks = new FakeWorkTasks();
+        tasks.Add(new WorkTask { Title = "Ohne Frist", DueDate = null });
+        tasks.Add(new WorkTask { Title = "Spät fällig", DueDate = DateOnly.FromDateTime(DateTime.Today.AddDays(10)) });
+        tasks.Add(new WorkTask { Title = "Bald fällig", DueDate = DateOnly.FromDateTime(DateTime.Today.AddDays(1)) });
+        var vm = new WorkTaskListViewModel(tasks, new FakeGroups([]));
+
+        Assert.Equal(["Bald fällig", "Spät fällig", "Ohne Frist"], vm.Tasks.Select(t => t.Title));
+    }
+}
+
+public sealed class AddEditWorkTaskDialogViewModelTests
+{
+    [Fact]
+    public void Save_OhneTitel_SetztFehlerUndErzeugtKeinResult()
+    {
+        var vm = new AddEditWorkTaskDialogViewModel(null, []);
+
+        vm.SaveCommand.Execute(null);
+
+        Assert.Null(vm.Result);
+        Assert.NotEmpty(vm.TitleError);
+    }
+
+    [Fact]
+    public void Save_MitGueltigenDaten_ErzeugtWorkTask()
+    {
+        var group = new LearningGroup { Name = "8a" };
+        var vm = new AddEditWorkTaskDialogViewModel(null, [group])
+        {
+            Title = "Klausur korrigieren",
+            SelectedCategory = TaskCategoryDisplay.Label(TaskCategory.Correction),
+            SelectedGroup = group,
+            DueDateText = "24.12.2026",
+            EstimatedMinutesText = "90",
+        };
+
+        vm.SaveCommand.Execute(null);
+
+        Assert.NotNull(vm.Result);
+        Assert.Equal("Klausur korrigieren", vm.Result!.Title);
+        Assert.Equal(TaskCategory.Correction, vm.Result.Category);
+        Assert.Equal(group.Id, vm.Result.GroupId);
+        Assert.Equal(new DateOnly(2026, 12, 24), vm.Result.DueDate);
+        Assert.Equal(90, vm.Result.EstimatedMinutes);
+    }
+
+    [Fact]
+    public void Save_MitUngueltigemDatum_SetztFehler()
+    {
+        var vm = new AddEditWorkTaskDialogViewModel(null, [])
+        {
+            Title = "T",
+            DueDateText = "nicht-ein-datum",
+        };
+
+        vm.SaveCommand.Execute(null);
+
+        Assert.Null(vm.Result);
+        Assert.NotEmpty(vm.DueDateError);
+    }
+
+    [Fact]
+    public void Save_BestehendeAufgabe_BehaeltIdUndStatus()
+    {
+        var source = new WorkTask { Title = "Alt", Status = WorkTaskStatus.InProgress };
+        var vm = new AddEditWorkTaskDialogViewModel(source, []) { Title = "Neu" };
+
+        vm.SaveCommand.Execute(null);
+
+        Assert.Equal(source.Id, vm.Result!.Id);
+        Assert.Equal(WorkTaskStatus.InProgress, vm.Result.Status);
+    }
+}

LehrerApp.Desktop/AppBootstrapper.cs

@@ -8,6 +8,7 @@ using LehrerApp.Desktop.ViewModels.Groups;
 using LehrerApp.Desktop.ViewModels.Planning;
 using LehrerApp.Desktop.ViewModels.Settings;
 using LehrerApp.Desktop.ViewModels.Students;
+using LehrerApp.Desktop.ViewModels.Workload;
 using LehrerApp.Sync;
 using LehrerApp.Sync.Crypto;
 using LehrerApp.Sync.Models;
@@ -187,6 +188,7 @@ public static class AppBootstrapper
         services.AddSingleton<GroupListViewModel>();
         services.AddSingleton<StudentListViewModel>();
         services.AddSingleton<TimetableViewModel>();
+        services.AddSingleton<WorkTaskListViewModel>();
 
         // Transient: neue Instanz pro Navigation (für Detailseiten)
         services.AddTransient<GroupDetailViewModel>();

LehrerApp.Desktop/ViewModels/MainWindowViewModel.cs

@@ -6,6 +6,7 @@ using LehrerApp.Desktop.ViewModels.Groups;
 using LehrerApp.Desktop.ViewModels.Planning;
 using LehrerApp.Desktop.ViewModels.Settings;
 using LehrerApp.Desktop.ViewModels.Students;
+using LehrerApp.Desktop.ViewModels.Workload;
 using Microsoft.Extensions.DependencyInjection;
 using System.Collections.ObjectModel;
 
@@ -66,7 +67,7 @@ public partial class MainWindowViewModel : ObservableObject
             NavItem.Students  => _services.GetRequiredService<StudentListViewModel>(),
             NavItem.Exams     => new PlaceholderViewModel { Title = "Klausuren", Icon = "📝" },
             NavItem.Planner   => GetTimetable(),
-            NavItem.Workload  => new PlaceholderViewModel { Title = "Arbeitszeit", Icon = "⏱" },
+            NavItem.Workload  => GetWorkload(),
             NavItem.Settings  => _services.GetRequiredService<SettingsViewModel>(),
             _                 => CurrentPage,
         };
@@ -88,6 +89,13 @@ public partial class MainWindowViewModel : ObservableObject
         return timetable;
     }
 
+    private WorkTaskListViewModel GetWorkload()
+    {
+        var workload = _services.GetRequiredService<WorkTaskListViewModel>();
+        workload.Load();
+        return workload;
+    }
+
     public void NavigateToGroupDetail(Guid groupId, int initialTab = 0)
     {
         ActiveNavItem     = NavItem.Groups;

LehrerApp.Desktop/ViewModels/Workload/WorkloadViewModels.cs

@@ -0,0 +1,266 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using System.Collections.ObjectModel;
+using System.Globalization;
+
+namespace LehrerApp.Desktop.ViewModels.Workload;
+
+// ── Anzeige-Hilfen für die Enums (6.1) ──────────────────────────────────────
+
+public static class WorkTaskStatusDisplay
+{
+    public static string Label(WorkTaskStatus s) => s switch
+    {
+        WorkTaskStatus.Open       => "Offen",
+        WorkTaskStatus.InProgress => "In Bearbeitung",
+        WorkTaskStatus.Done       => "Erledigt",
+        _                         => s.ToString(),
+    };
+
+    public static string ColorHex(WorkTaskStatus s) => s switch
+    {
+        WorkTaskStatus.Open       => "#9E9E9E",
+        WorkTaskStatus.InProgress => "#1976D2",
+        WorkTaskStatus.Done       => "#43A047",
+        _                         => "#9E9E9E",
+    };
+
+    // Klick auf die Status-Kachel wechselt reihum (6.1.3).
+    public static WorkTaskStatus Next(WorkTaskStatus s) => s switch
+    {
+        WorkTaskStatus.Open       => WorkTaskStatus.InProgress,
+        WorkTaskStatus.InProgress => WorkTaskStatus.Done,
+        _                         => WorkTaskStatus.Open,
+    };
+}
+
+public static class TaskCategoryDisplay
+{
+    public static string Label(TaskCategory c) => c switch
+    {
+        TaskCategory.Correction  => "Korrektur",
+        TaskCategory.Preparation => "Vorbereitung",
+        TaskCategory.Admin       => "Verwaltung",
+        TaskCategory.Meeting     => "Besprechung",
+        TaskCategory.Other       => "Sonstiges",
+        _                        => c.ToString(),
+    };
+
+    public static string[] Options { get; } = Enum.GetValues<TaskCategory>().Select(Label).ToArray();
+
+    public static TaskCategory FromLabel(string? label) =>
+        Enum.GetValues<TaskCategory>().FirstOrDefault(c => Label(c) == label, TaskCategory.Other);
+}
+
+// ── Aufgabenliste (6.1.1, 6.1.3) ─────────────────────────────────────────────
+
+public partial class WorkTaskListViewModel : ObservableObject
+{
+    private readonly IWorkTaskRepository _tasks;
+    private readonly IGroupRepository _groups;
+
+    public const string AllFilter = "Alle";
+    public const string ActiveFilter = "Offene Aufgaben";
+    public const string DoneFilter = "Erledigt";
+    public const string NoGroupFilter = "Ohne Gruppe";
+
+    [ObservableProperty] private string _statusFilter = ActiveFilter;
+    [ObservableProperty] private string _categoryFilter = AllFilter;
+    [ObservableProperty] private string _groupFilter = AllFilter;
+
+    public List<string> StatusFilterOptions { get; } = [ActiveFilter, AllFilter, DoneFilter];
+    public List<string> CategoryFilterOptions { get; } = [AllFilter, .. TaskCategoryDisplay.Options];
+    public ObservableCollection<string> GroupFilterOptions { get; } = [AllFilter, NoGroupFilter];
+
+    public ObservableCollection<WorkTaskListItem> Tasks { get; } = [];
+    public string CountSummary => $"{Tasks.Count} Aufgabe(n)";
+
+    public Func<WorkTask?, Task<WorkTask?>>? OnEditTask { get; set; }
+
+    private Dictionary<Guid, string> _groupNames = [];
+
+    public WorkTaskListViewModel(IWorkTaskRepository tasks, IGroupRepository groups)
+    {
+        _tasks = tasks;
+        _groups = groups;
+        Load();
+    }
+
+    partial void OnStatusFilterChanged(string value) => Refresh();
+    partial void OnCategoryFilterChanged(string value) => Refresh();
+    partial void OnGroupFilterChanged(string value) => Refresh();
+
+    public void Load()
+    {
+        var groups = _groups.GetAll(includeInactive: true);
+        _groupNames = groups.ToDictionary(g => g.Id, g => g.Name);
+
+        GroupFilterOptions.Clear();
+        GroupFilterOptions.Add(AllFilter);
+        GroupFilterOptions.Add(NoGroupFilter);
+        foreach (var name in groups.Select(g => g.Name).OrderBy(n => n))
+            GroupFilterOptions.Add(name);
+
+        Refresh();
+    }
+
+    private void Refresh()
+    {
+        Tasks.Clear();
+        var all = _tasks.GetAll().AsEnumerable();
+
+        all = StatusFilter switch
+        {
+            ActiveFilter => all.Where(t => t.Status != WorkTaskStatus.Done),
+            DoneFilter   => all.Where(t => t.Status == WorkTaskStatus.Done),
+            _            => all,
+        };
+
+        if (CategoryFilter != AllFilter)
+        {
+            var category = TaskCategoryDisplay.FromLabel(CategoryFilter);
+            all = all.Where(t => t.Category == category);
+        }
+
+        if (GroupFilter == NoGroupFilter)
+            all = all.Where(t => t.GroupId is null);
+        else if (GroupFilter != AllFilter)
+            all = all.Where(t => t.GroupId.HasValue && _groupNames.GetValueOrDefault(t.GroupId.Value) == GroupFilter);
+
+        // Fälligkeit: fällige zuerst, unbefristete ans Ende (6.1.1).
+        foreach (var t in all.OrderBy(t => t.DueDate ?? DateOnly.MaxValue).ThenBy(t => t.Title))
+            Tasks.Add(new WorkTaskListItem(t, _groupNames.GetValueOrDefault(t.GroupId ?? Guid.Empty)));
+
+        OnPropertyChanged(nameof(CountSummary));
+    }
+
+    [RelayCommand]
+    private async Task AddTask()
+    {
+        if (OnEditTask is null) return;
+        var result = await OnEditTask(null);
+        if (result is null) return;
+        _tasks.Save(result);
+        Refresh();
+    }
+
+    [RelayCommand]
+    private async Task EditTask(WorkTaskListItem? item)
+    {
+        if (item is null || OnEditTask is null) return;
+        var result = await OnEditTask(item.Model);
+        if (result is null) return;
+        _tasks.Save(result);
+        Refresh();
+    }
+
+    [RelayCommand]
+    private void CycleStatus(WorkTaskListItem? item)
+    {
+        if (item is null) return;
+        item.Model.Status = WorkTaskStatusDisplay.Next(item.Model.Status);
+        _tasks.Save(item.Model);
+        Refresh();
+    }
+
+    [RelayCommand]
+    private void DeleteTask(WorkTaskListItem? item)
+    {
+        if (item is null) return;
+        _tasks.Delete(item.Model.Id);
+        Refresh();
+    }
+}
+
+public class WorkTaskListItem(WorkTask model, string? groupName)
+{
+    public WorkTask Model { get; } = model;
+    public string Title => Model.Title;
+    public string CategoryLabel => TaskCategoryDisplay.Label(Model.Category);
+    public string GroupName => groupName ?? "";
+    public string DueDateDisplay => Model.DueDate?.ToString("dd.MM.yyyy", CultureInfo.InvariantCulture) ?? "";
+    public bool IsOverdue => Model.DueDate is { } d && d < DateOnly.FromDateTime(DateTime.Today)
+        && Model.Status != WorkTaskStatus.Done;
+    public string DueDateColorHex => IsOverdue ? "#D32F2F" : "#9E9E9E";
+    public string StatusLabel => WorkTaskStatusDisplay.Label(Model.Status);
+    public string StatusColorHex => WorkTaskStatusDisplay.ColorHex(Model.Status);
+    public string EstimatedMinutesDisplay => Model.EstimatedMinutes is { } m ? $"{m} min" : "";
+}
+
+// ── Dialog: Aufgabe anlegen/bearbeiten (6.1.2) ───────────────────────────────
+
+public partial class AddEditWorkTaskDialogViewModel : ObservableObject
+{
+    private readonly WorkTask? _source;
+
+    [ObservableProperty] private string _title = "";
+    [ObservableProperty] private string _selectedCategory = TaskCategoryDisplay.Options[0];
+    [ObservableProperty] private LearningGroup? _selectedGroup;
+    [ObservableProperty] private string _dueDateText = "";
+    [ObservableProperty] private string _estimatedMinutesText = "";
+    [ObservableProperty] private string _notes = "";
+    [ObservableProperty] private string _titleError = "";
+    [ObservableProperty] private string _dueDateError = "";
+    [ObservableProperty] private string _estimatedMinutesError = "";
+
+    public string DialogTitle => _source is null ? "Aufgabe anlegen" : "Aufgabe bearbeiten";
+    public List<string> CategoryOptions { get; } = [.. TaskCategoryDisplay.Options];
+    public List<LearningGroup> Groups { get; }
+    public WorkTask? Result { get; private set; }
+
+    public AddEditWorkTaskDialogViewModel(WorkTask? source, List<LearningGroup> groups)
+    {
+        _source = source;
+        Groups = groups;
+        if (source is null) return;
+
+        Title = source.Title;
+        SelectedCategory = TaskCategoryDisplay.Label(source.Category);
+        SelectedGroup = source.GroupId is { } id ? groups.FirstOrDefault(g => g.Id == id) : null;
+        DueDateText = source.DueDate?.ToString("dd.MM.yyyy", CultureInfo.InvariantCulture) ?? "";
+        EstimatedMinutesText = source.EstimatedMinutes?.ToString(CultureInfo.InvariantCulture) ?? "";
+        Notes = source.Notes ?? "";
+    }
+
+    [RelayCommand]
+    private void Save()
+    {
+        TitleError = ""; DueDateError = ""; EstimatedMinutesError = "";
+        var valid = true;
+
+        if (string.IsNullOrWhiteSpace(Title)) { TitleError = "Titel erforderlich."; valid = false; }
+
+        DateOnly? dueDate = null;
+        if (!string.IsNullOrWhiteSpace(DueDateText))
+        {
+            if (!DateOnly.TryParseExact(DueDateText, "dd.MM.yyyy", null, DateTimeStyles.None, out var d))
+            { DueDateError = "Format TT.MM.JJJJ."; valid = false; }
+            else dueDate = d;
+        }
+
+        int? estimatedMinutes = null;
+        if (!string.IsNullOrWhiteSpace(EstimatedMinutesText))
+        {
+            if (!int.TryParse(EstimatedMinutesText, out var m) || m <= 0)
+            { EstimatedMinutesError = "Ganze Zahl > 0 erwartet."; valid = false; }
+            else estimatedMinutes = m;
+        }
+
+        if (!valid) return;
+
+        Result = new WorkTask
+        {
+            Id               = _source?.Id ?? Guid.NewGuid(),
+            Title            = Title.Trim(),
+            Category         = TaskCategoryDisplay.FromLabel(SelectedCategory),
+            GroupId          = SelectedGroup?.Id,
+            DueDate          = dueDate,
+            EstimatedMinutes = estimatedMinutes,
+            Status           = _source?.Status ?? WorkTaskStatus.Open,
+            Notes            = string.IsNullOrWhiteSpace(Notes) ? null : Notes.Trim(),
+            CreatedAt        = _source?.CreatedAt ?? DateTime.UtcNow,
+        };
+    }
+}

LehrerApp.Desktop/Views/MainWindow.axaml

@@ -11,6 +11,8 @@
         xmlns:vmset="clr-namespace:LehrerApp.Desktop.ViewModels.Settings"
         xmlns:vp="clr-namespace:LehrerApp.Desktop.Views.Planning"
         xmlns:vmp="clr-namespace:LehrerApp.Desktop.ViewModels.Planning"
+        xmlns:vw="clr-namespace:LehrerApp.Desktop.Views.Workload"
+        xmlns:vmw="clr-namespace:LehrerApp.Desktop.ViewModels.Workload"
         xmlns:svc="clr-namespace:LehrerApp.Desktop.Services"
         x:Class="LehrerApp.Desktop.Views.MainWindow"
         x:DataType="vm:MainWindowViewModel"
@@ -53,6 +55,9 @@
       <DataTemplate DataType="vmp:TimetableViewModel">
         <vp:TimetableView/>
       </DataTemplate>
+      <DataTemplate DataType="vmw:WorkTaskListViewModel">
+        <vw:WorkTaskListView/>
+      </DataTemplate>
       <DataTemplate DataType="vm:PlaceholderViewModel">
         <views:PlaceholderView/>
       </DataTemplate>

LehrerApp.Desktop/Views/Workload/AddEditWorkTaskDialog.axaml

@@ -0,0 +1,69 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Workload"
+        xmlns:models="clr-namespace:LehrerApp.Core.Models;assembly=LehrerApp.Core"
+        x:Class="LehrerApp.Desktop.Views.Workload.AddEditWorkTaskDialog"
+        x:DataType="vm:AddEditWorkTaskDialogViewModel"
+        Title="{Binding DialogTitle}"
+        Width="420" Height="480" MinWidth="380" MinHeight="420"
+        CanResize="True" WindowStartupLocation="CenterOwner">
+
+  <Grid RowDefinitions="*,Auto" Margin="24">
+    <ScrollViewer Grid.Row="0">
+      <StackPanel Spacing="14" Margin="0,0,12,0">
+        <TextBlock Text="{Binding DialogTitle}" Classes="dialogtitle"/>
+
+        <StackPanel Spacing="4">
+          <TextBlock Text="Titel *" FontSize="12" Opacity="0.7"/>
+          <TextBox Text="{Binding Title}" PlaceholderText="z.B. Klausur 8a korrigieren"/>
+          <TextBlock Text="{Binding TitleError}" Foreground="Red" FontSize="11"
+                     IsVisible="{Binding TitleError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+        </StackPanel>
+
+        <Grid ColumnDefinitions="*,8,*">
+          <StackPanel Grid.Column="0" Spacing="4">
+            <TextBlock Text="Kategorie *" FontSize="12" Opacity="0.7"/>
+            <ComboBox ItemsSource="{Binding CategoryOptions}" SelectedItem="{Binding SelectedCategory}"
+                      HorizontalAlignment="Stretch"/>
+          </StackPanel>
+          <StackPanel Grid.Column="2" Spacing="4">
+            <TextBlock Text="Gruppe (optional)" FontSize="12" Opacity="0.7"/>
+            <ComboBox ItemsSource="{Binding Groups}" SelectedItem="{Binding SelectedGroup}"
+                      HorizontalAlignment="Stretch" PlaceholderText="Keine Gruppe">
+              <ComboBox.ItemTemplate>
+                <DataTemplate x:DataType="models:LearningGroup">
+                  <TextBlock Text="{Binding Name}"/>
+                </DataTemplate>
+              </ComboBox.ItemTemplate>
+            </ComboBox>
+          </StackPanel>
+        </Grid>
+
+        <Grid ColumnDefinitions="*,8,*">
+          <StackPanel Grid.Column="0" Spacing="4">
+            <TextBlock Text="Fällig am (optional)" FontSize="12" Opacity="0.7"/>
+            <TextBox Text="{Binding DueDateText}" PlaceholderText="TT.MM.JJJJ"/>
+            <TextBlock Text="{Binding DueDateError}" Foreground="Red" FontSize="11"
+                       IsVisible="{Binding DueDateError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+          </StackPanel>
+          <StackPanel Grid.Column="2" Spacing="4">
+            <TextBlock Text="Geschätzte Dauer in min (optional)" FontSize="12" Opacity="0.7"/>
+            <TextBox Text="{Binding EstimatedMinutesText}" PlaceholderText="z.B. 90"/>
+            <TextBlock Text="{Binding EstimatedMinutesError}" Foreground="Red" FontSize="11"
+                       IsVisible="{Binding EstimatedMinutesError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+          </StackPanel>
+        </Grid>
+
+        <StackPanel Spacing="4">
+          <TextBlock Text="Notizen (optional)" FontSize="12" Opacity="0.7"/>
+          <TextBox Text="{Binding Notes}" AcceptsReturn="True" TextWrapping="Wrap" Height="80"/>
+        </StackPanel>
+      </StackPanel>
+    </ScrollViewer>
+
+    <Grid Grid.Row="1" ColumnDefinitions="*,8,*" Margin="0,20,0,0">
+      <Button Grid.Column="0" Content="Abbrechen" HorizontalAlignment="Stretch" Click="OnCancel"/>
+      <Button Grid.Column="2" Content="Speichern" HorizontalAlignment="Stretch" Click="OnSave"/>
+    </Grid>
+  </Grid>
+</Window>

LehrerApp.Desktop/Views/Workload/AddEditWorkTaskDialog.axaml.cs

@@ -0,0 +1,21 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using LehrerApp.Desktop.ViewModels.Workload;
+
+namespace LehrerApp.Desktop.Views.Workload;
+
+public partial class AddEditWorkTaskDialog : Window
+{
+    public AddEditWorkTaskDialog() => InitializeComponent();
+
+    private void OnSave(object? s, RoutedEventArgs e)
+    {
+        if (DataContext is AddEditWorkTaskDialogViewModel vm && vm.SaveCommand.CanExecute(null))
+        {
+            vm.SaveCommand.Execute(null);
+            if (vm.Result is not null) Close(true);
+        }
+    }
+
+    private void OnCancel(object? s, RoutedEventArgs e) => Close(false);
+}

LehrerApp.Desktop/Views/Workload/WorkTaskListView.axaml

@@ -0,0 +1,70 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Workload"
+             xmlns:shared="clr-namespace:LehrerApp.Desktop.Views.Shared"
+             x:Class="LehrerApp.Desktop.Views.Workload.WorkTaskListView"
+             x:DataType="vm:WorkTaskListViewModel">
+  <Grid RowDefinitions="Auto,Auto,*">
+    <Border Grid.Row="0" Padding="20,16"
+            BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+            BorderThickness="0,0,0,1">
+      <Grid ColumnDefinitions="*,Auto">
+        <shared:PageHeader Grid.Column="0" Title="Arbeitszeit" Subtitle="{Binding CountSummary}"/>
+        <Button Grid.Column="1" Content="＋ Neue Aufgabe"
+                Command="{Binding AddTaskCommand}" VerticalAlignment="Center"/>
+      </Grid>
+    </Border>
+
+    <Grid Grid.Row="1" ColumnDefinitions="Auto,Auto,Auto" Margin="16,10" HorizontalAlignment="Left">
+      <ComboBox Grid.Column="0" ItemsSource="{Binding StatusFilterOptions}"
+                SelectedItem="{Binding StatusFilter}" Margin="0,0,8,0"/>
+      <ComboBox Grid.Column="1" ItemsSource="{Binding CategoryFilterOptions}"
+                SelectedItem="{Binding CategoryFilter}" Margin="0,0,8,0"/>
+      <ComboBox Grid.Column="2" ItemsSource="{Binding GroupFilterOptions}"
+                SelectedItem="{Binding GroupFilter}"/>
+    </Grid>
+
+    <ScrollViewer Grid.Row="2" Margin="16,0,16,16">
+      <StackPanel>
+        <ItemsControl ItemsSource="{Binding Tasks}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:WorkTaskListItem">
+              <Border Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+                      CornerRadius="6" Padding="12,10" Margin="0,0,0,8">
+                <Grid ColumnDefinitions="Auto,*,Auto,Auto,Auto,Auto">
+                  <Button Grid.Column="0" Background="{Binding StatusColorHex}" Padding="8,4"
+                          CornerRadius="4" VerticalAlignment="Center"
+                          Command="{Binding $parent[ItemsControl].((vm:WorkTaskListViewModel)DataContext).CycleStatusCommand}"
+                          CommandParameter="{Binding}"
+                          ToolTip.Tip="Klicken, um den Status zu wechseln">
+                    <TextBlock Text="{Binding StatusLabel}" FontSize="12" Foreground="White"/>
+                  </Button>
+                  <StackPanel Grid.Column="1" Margin="10,0" VerticalAlignment="Center">
+                    <TextBlock Text="{Binding Title}" FontWeight="SemiBold" FontSize="13"/>
+                    <TextBlock FontSize="11" Opacity="0.6">
+                      <Run Text="{Binding CategoryLabel}"/>
+                      <Run Text=" · "/>
+                      <Run Text="{Binding GroupName}"/>
+                    </TextBlock>
+                  </StackPanel>
+                  <TextBlock Grid.Column="2" Text="{Binding DueDateDisplay}" VerticalAlignment="Center"
+                             Margin="0,0,10,0" FontSize="12" Foreground="{Binding DueDateColorHex}"/>
+                  <TextBlock Grid.Column="3" Text="{Binding EstimatedMinutesDisplay}"
+                             VerticalAlignment="Center" Opacity="0.6" FontSize="12" Margin="0,0,10,0"/>
+                  <Button Grid.Column="4" Content="Bearbeiten" FontSize="11" Padding="8,3" Margin="0,0,4,0"
+                          Command="{Binding $parent[ItemsControl].((vm:WorkTaskListViewModel)DataContext).EditTaskCommand}"
+                          CommandParameter="{Binding}"/>
+                  <Button Grid.Column="5" Content="Löschen" FontSize="11" Padding="8,3"
+                          Command="{Binding $parent[ItemsControl].((vm:WorkTaskListViewModel)DataContext).DeleteTaskCommand}"
+                          CommandParameter="{Binding}"/>
+                </Grid>
+              </Border>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+        <TextBlock Text="Keine Aufgaben in dieser Filteransicht." Opacity="0.6" Margin="4,12"
+                   IsVisible="{Binding !Tasks.Count}"/>
+      </StackPanel>
+    </ScrollViewer>
+  </Grid>
+</UserControl>

LehrerApp.Desktop/Views/Workload/WorkTaskListView.axaml.cs

@@ -0,0 +1,31 @@
+using Avalonia.Controls;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Desktop.ViewModels.Workload;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LehrerApp.Desktop.Views.Workload;
+
+public partial class WorkTaskListView : UserControl
+{
+    public WorkTaskListView() => InitializeComponent();
+
+    protected override void OnDataContextChanged(EventArgs e)
+    {
+        base.OnDataContextChanged(e);
+        if (DataContext is WorkTaskListViewModel vm)
+            vm.OnEditTask = ShowEditDialog;
+    }
+
+    private async Task<WorkTask?> ShowEditDialog(WorkTask? source)
+    {
+        var owner = TopLevel.GetTopLevel(this) as Window;
+        if (owner is null) return null;
+
+        var groups = App.Services.GetRequiredService<IGroupRepository>().GetAll(includeInactive: true);
+        var vm = new AddEditWorkTaskDialogViewModel(source, groups);
+        var dialog = new AddEditWorkTaskDialog { DataContext = vm };
+        await dialog.ShowDialog<bool>(owner);
+        return vm.Result;
+    }
+}

TODO.md

@@ -778,13 +778,22 @@ dadurch faktisch schon (Quick-Input-Dialog bzw. "Offene Entschuldigungen" im Das
 ## 6. Arbeitszeit & Aufgaben
 
 Modelle `WorkTask` und `TimeEntry` existieren, Repositories ebenfalls.
-Navigationspunkt "Arbeitszeit" ist ein `PlaceholderViewModel`.
+Navigationspunkt "Arbeitszeit" zeigt inzwischen die Aufgabenverwaltung (6.1) statt eines
+Placeholders; Zeiterfassung (6.2/6.3) ist noch offen.
 
 ### 6.1 Aufgabenverwaltung
-- [ ] **6.1.1** Aufgabenliste mit Filter nach Status, Kategorie, Gruppe und Fälligkeit.
-- [ ] **6.1.2** Aufgabe anlegen/bearbeiten: Titel, Kategorie, Gruppe, Fälligkeit,
-      geschätzte Dauer, Notizen.
-- [ ] **6.1.3** Status per Klick wechseln (`Open → InProgress → Done`), erledigte ausblenden.
+- [x] **6.1.1** Aufgabenliste mit Filter nach Status, Kategorie, Gruppe und Fälligkeit —
+      `WorkTaskListViewModel`/`WorkTaskListView`. Drei Filter-ComboBoxen (Status/Kategorie/Gruppe);
+      "Fälligkeit" als Sortierung (fällige zuerst, unbefristete ans Ende) statt eigenem
+      Datumsbereich-Filter umgesetzt, da eine Liste mit wenigen Dutzend Aufgaben davon mehr
+      profitiert als von einer zusätzlichen Filter-UI.
+- [x] **6.1.2** Aufgabe anlegen/bearbeiten: Titel, Kategorie, Gruppe, Fälligkeit,
+      geschätzte Dauer, Notizen — `AddEditWorkTaskDialog`, gleiches Feld-Fehler-Muster wie die
+      übrigen Dialoge (`{Field}Error` je Feld, Validierung sammelt statt beim ersten Fehler
+      abzubrechen).
+- [x] **6.1.3** Status per Klick wechseln (`Open → InProgress → Done → Open`) über eine farbige
+      Status-Kachel je Zeile; "Offene Aufgaben" (alles außer `Done`) ist der Default-Filter, damit
+      Erledigtes automatisch ausgeblendet ist, ohne separate Sichtbarkeits-Logik.
 - [ ] **6.1.4** Wiederkehrende Aufgaben (wöchentlich/monatlich).
 - [ ] **6.1.5** Automatische Aufgabe "Klausur korrigieren" beim Statuswechsel einer Klausur
       auf `Conducted` (Anbindung an 1.1.3).