fix: Fehlzeitenkalender in Templates

LehrerApp.Desktop.Tests/CreateLetterDialogViewModelTests.cs

@@ -56,7 +56,7 @@ public sealed class CreateLetterDialogViewModelTests : IDisposable
     }
 
     [Fact]
-    public void AdvancedContent_Anwesenheitskalender_WirdAlsDrawingGerendert()
+    public async Task AdvancedContent_Anwesenheitskalender_WirdAlsDrawingGerendert()
     {
         var store = StoreWithTemplate(new PlaceholderDefinition(
             StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
@@ -66,7 +66,7 @@ public sealed class CreateLetterDialogViewModelTests : IDisposable
         var output = Path.Combine(_directory, "Kalender.pdf");
 
         Assert.True(vm.UsesAttendanceCalendar);
-        vm.SetAttendanceCalendarOptions(new AttendanceCalendarOptions(
+        await vm.SetAttendanceCalendarOptionsAsync(new AttendanceCalendarOptions(
             new DateOnly(2026, 8, 19), 3, AttendanceCalendarSize.Large));
         Assert.True(vm.AttendanceCalendarConfigured);
         Assert.Contains("August 2026", vm.AttendanceCalendarSummary);
@@ -76,6 +76,45 @@ public sealed class CreateLetterDialogViewModelTests : IDisposable
         Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
     }
 
+    [Fact]
+    public async Task AttendanceKalenderKonfigurieren_LoestGezieltenDatenAbrufFuerDenZeitraumAus()
+    {
+        var store = StoreWithTemplate(new PlaceholderDefinition(
+            StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
+        AttendanceCalendarOptions? requested = null;
+        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
+            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
+            _ => new DrawingValue([], 0), attendanceDataRefresher: (options, _) =>
+            { requested = options; return Task.CompletedTask; });
+
+        await vm.SetAttendanceCalendarOptionsAsync(new AttendanceCalendarOptions(
+            new DateOnly(2026, 9, 1), 2, AttendanceCalendarSize.Medium));
+
+        Assert.NotNull(requested);
+        Assert.Equal(new DateOnly(2026, 9, 1), requested!.NormalizedStartMonth);
+        Assert.Equal(2, requested.NormalizedMonthCount);
+        Assert.False(vm.IsRefreshingAttendanceData);
+        Assert.Equal("", vm.AttendanceRefreshError);
+    }
+
+    [Fact]
+    public async Task AttendanceKalenderKonfigurieren_ZeigtFehlerBeiFehlgeschlagenemAbrufAnStattZuBlockieren()
+    {
+        var store = StoreWithTemplate(new PlaceholderDefinition(
+            StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
+        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
+            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
+            _ => new DrawingValue([], 0),
+            attendanceDataRefresher: (_, _) => throw new WebUntisIntegrationException("Keine Verbindung."));
+
+        await vm.SetAttendanceCalendarOptionsAsync(new AttendanceCalendarOptions(
+            new DateOnly(2026, 9, 1), 1, AttendanceCalendarSize.Medium));
+
+        Assert.True(vm.AttendanceCalendarConfigured);
+        Assert.Contains("Keine Verbindung.", vm.AttendanceRefreshError);
+        Assert.False(vm.IsRefreshingAttendanceData);
+    }
+
     [Fact]
     public void AdvancedContent_Fehlzeitenliste_AktiviertKonfigurationsschritt()
     {
@@ -116,6 +155,42 @@ public sealed class CreateLetterDialogViewModelTests : IDisposable
         Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
     }
 
+    [Fact]
+    public void StudentName_WirdAutomatischMitVollemNamenBefuellt()
+    {
+        var store = StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true),
+            new PlaceholderDefinition("Datum", PlaceholderType.Date, true),
+            new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline, true),
+            new PlaceholderDefinition("Student.Name", PlaceholderType.Text, true));
+        var vm = Build(StudentWithContact("Sehr geehrte Frau Muster,"), store);
+        vm.LetterText = "Dies ist der Inhalt.";
+
+        Assert.Empty(vm.CustomPlaceholders);
+        Assert.True(vm.CanGenerate);
+        var output = Path.Combine(_directory, "StudentName.pdf");
+        Assert.True(vm.Generate(output));
+    }
+
+    [Fact]
+    public void Anrede_WirdAusKontaktVorbelegtUndBleibtEditierbar()
+    {
+        var store = StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true),
+            new PlaceholderDefinition("Datum", PlaceholderType.Date, true),
+            new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline, true));
+        var vm = Build(StudentWithContact(null), store);
+        vm.LetterText = "Dies ist der Inhalt.";
+
+        Assert.Equal("", vm.Anrede);
+        Assert.False(vm.CanGenerate);
+        Assert.Contains(vm.Issues, i => i.Message.Contains("Anrede", StringComparison.OrdinalIgnoreCase));
+
+        vm.Anrede = "Sehr geehrte Familie Beispiel,";
+        var output = Path.Combine(_directory, "AnredeManuell.pdf");
+
+        Assert.True(vm.CanGenerate);
+        Assert.True(vm.Generate(output));
+    }
+
     private CreateLetterDialogViewModel Build(Student student, TemplateStore store) =>
         new(student, store, new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]));
 

LehrerApp.Desktop/Services/LetterDialogs.cs

@@ -22,10 +22,27 @@ public static class LetterDialogs
             App.Services.GetRequiredService<IGroupRepository>(),
             options => App.Services.GetRequiredService<StudentAttendanceCalendarService>().Build(student, options),
             options => App.Services.GetRequiredService<StudentAttendanceCalendarService>()
-                .BuildAbsenceDayList(student, options));
+                .BuildAbsenceDayList(student, options),
+            RefreshAttendanceDataAsync);
         var dialog = new CreateLetterDialog { DataContext = vm };
         var path = await dialog.ShowDialog<string?>(owner);
         if (!string.IsNullOrEmpty(path) && File.Exists(path))
             System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(path) { UseShellExecute = true });
     }
+
+    /// <summary>Holt genau den im Anwesenheitskalender-Dialog gewählten Zeitraum gezielt per
+    /// WebUntis nach (ausgelöst durch den expliziten "Konfigurieren…"-Klick, kein Hintergrundabruf
+    /// beim bloßen Öffnen des Briefdialogs). Damit sieht <see cref="StudentAttendanceCalendarService"/>
+    /// anschließend frische Daten im lokalen Cache, statt stillschweigend "keine Fehltage" zu
+    /// melden, nur weil die Klassenlehrer-Übersicht für diesen Zeitraum noch nie geöffnet wurde.</summary>
+    private static async Task RefreshAttendanceDataAsync(AttendanceCalendarOptions options, CancellationToken token)
+    {
+        var className = App.Services.GetRequiredService<WebUntisSettingsService>().HomeroomClassName;
+        if (string.IsNullOrWhiteSpace(className)) return;
+        var cache = App.Services.GetRequiredService<UntisReportCacheService>();
+        var start = options.NormalizedStartMonth;
+        var end = start.AddMonths(options.NormalizedMonthCount).AddDays(-1);
+        await cache.GetAbsencesAsync(className, start, end, token: token);
+        await cache.GetClassRegisterEventsAsync(className, start, end, token: token);
+    }
 }

LehrerApp.Desktop/Services/LetterPlaceholderBuilder.cs

@@ -26,6 +26,7 @@ public static class LetterPlaceholderBuilder
             ["Empfaenger"] = new TextValue(contact?.Name ?? ""), ["Anrede"] = new TextValue(contact?.LetterSalutation ?? ""),
             ["Brieftext"] = new MultilineValue(letterText), ["LehrerName"] = new TextValue(teacherName),
             ["Student.FirstName"] = new TextValue(student.FirstName), ["Student.LastName"] = new TextValue(student.LastName),
+            ["Student.Name"] = new TextValue(student.FullName),
             ["Contact.Name"] = new TextValue(contact?.Name ?? ""), ["Contact.Address"] = new MultilineValue(address),
             ["Contact.Street"] = new TextValue(contact?.Street ?? ""), ["Contact.PostalCode"] = new TextValue(contact?.PostalCode ?? ""),
             ["Contact.City"] = new TextValue(contact?.City ?? ""), ["Letter.Salutation"] = new TextValue(contact?.LetterSalutation ?? ""),

LehrerApp.Desktop/Services/StudentAttendanceCalendarDrawingBuilder.cs

@@ -43,15 +43,15 @@ public static class StudentAttendanceCalendarDrawingBuilder
         var monthGap = 6 * scale;
         var first = options.NormalizedStartMonth;
         var monthCount = options.NormalizedMonthCount;
-        var commands = new List<DrawingCommand>
+        var commands = new List<DrawingCommand>();
-        {
+        var y = 0f;
-            new DrawStringEx(0, 0, 7 * scale, contentWidth, "Anwesenheit",
+        commands.Add(new DrawStringEx(0, y, 14 * scale, contentWidth, "Anwesenheit",
-                DrawingTextAlignment.AlignLeft, 11 * scale, Color: "#1F2937", Bold: true),
+            DrawingTextAlignment.AlignLeft, 11 * scale, Color: "#1F2937", Bold: true));
-            new DrawStringEx(0, 7 * scale, 6 * scale, contentWidth, studentName,
+        y += 14 * scale;
-                DrawingTextAlignment.AlignLeft, 8 * scale, Color: "#6B7280"),
+        commands.Add(new DrawStringEx(0, y, 10 * scale, contentWidth, studentName,
-        };
+            DrawingTextAlignment.AlignLeft, 8 * scale, Color: "#6B7280"));
+        y += 10 * scale + 2 * scale;
         var weekdays = new[] { "Mo", "Di", "Mi", "Do", "Fr", "Sa", "So" };
-        var y = 15 * scale;
         for (var monthIndex = 0; monthIndex < monthCount; monthIndex++)
         {
             var current = first.AddMonths(monthIndex);
@@ -59,14 +59,14 @@ public static class StudentAttendanceCalendarDrawingBuilder
                 DateOnly.FromDateTime(DateTime.Today), studentName);
             var offset = ((int)current.DayOfWeek + 6) % 7;
             var weeks = (int)Math.Ceiling((offset + days.Count) / 7d);
-            commands.Add(new DrawStringEx(0, y, 7 * scale, contentWidth,
+            commands.Add(new DrawStringEx(0, y, 11 * scale, contentWidth,
                 current.ToString("MMMM yyyy", CultureInfo.GetCultureInfo("de-DE")),
                 DrawingTextAlignment.AlignLeft, 9 * scale, Color: "#374151", Bold: true));
-            y += 7 * scale;
+            y += 11 * scale;
             for (var column = 0; column < 7; column++)
-                commands.Add(new DrawStringEx(column * cellWidth, y, 6 * scale, cellWidth, weekdays[column],
+                commands.Add(new DrawStringEx(column * cellWidth, y, 9 * scale, cellWidth, weekdays[column],
                     DrawingTextAlignment.AlignCenter, 7 * scale, Color: "#6B7280", Bold: true));
-            y += 7 * scale;
+            y += 9 * scale;
 
             foreach (var day in days)
             {
@@ -115,20 +115,20 @@ public static class StudentAbsenceDayListDrawingBuilder
                         UntisNameMatching.NamesMatch(a.StudentName, studentName))
             .OrderBy(a => a.Date)
             .ToList();
-        var commands = new List<DrawingCommand>
+        var commands = new List<DrawingCommand>();
-        {
+        var y = 0f;
-            new DrawStringEx(0, 0, 7 * scale, contentWidth, "Fehltage",
+        commands.Add(new DrawStringEx(0, y, 14 * scale, contentWidth, "Fehltage",
-                DrawingTextAlignment.AlignLeft, 11 * scale, Color: "#1F2937", Bold: true),
+            DrawingTextAlignment.AlignLeft, 11 * scale, Color: "#1F2937", Bold: true));
-            new DrawStringEx(0, 7 * scale, 6 * scale, contentWidth, studentName,
+        y += 14 * scale;
-                DrawingTextAlignment.AlignLeft, 8 * scale, Color: "#6B7280"),
+        commands.Add(new DrawStringEx(0, y, 10 * scale, contentWidth, studentName,
-        };
+            DrawingTextAlignment.AlignLeft, 8 * scale, Color: "#6B7280"));
-        var y = 16 * scale;
+        y += 10 * scale + 2 * scale;
         commands.Add(new DrawRectangle(0, y, contentWidth, rowHeight, "#CBD5E1", .4f, "#F3F4F6"));
-        commands.Add(new DrawStringEx(2 * scale, y + scale, rowHeight - 2 * scale, 31 * scale, "Datum",
+        commands.Add(new DrawStringEx(2 * scale, y + scale, rowHeight - scale, 31 * scale, "Datum",
             DrawingTextAlignment.AlignLeft, 7.5f * scale, Color: "#374151", Bold: true));
-        commands.Add(new DrawStringEx(36 * scale, y + scale, rowHeight - 2 * scale, 75 * scale, "Umfang",
+        commands.Add(new DrawStringEx(36 * scale, y + scale, rowHeight - scale, 75 * scale, "Umfang",
             DrawingTextAlignment.AlignLeft, 7.5f * scale, Color: "#374151", Bold: true));
-        commands.Add(new DrawStringEx(113 * scale, y + scale, rowHeight - 2 * scale, 55 * scale, "Status",
+        commands.Add(new DrawStringEx(113 * scale, y + scale, rowHeight - scale, 55 * scale, "Status",
             DrawingTextAlignment.AlignLeft, 7.5f * scale, Color: "#374151", Bold: true));
         y += rowHeight;
 
@@ -157,12 +157,12 @@ public static class StudentAbsenceDayListDrawingBuilder
                         : row.FriendlyStatusLabel;
                 var statusColor = row.IsUnexcused ? "#C62828" : "#2E7D32";
                 commands.Add(new DrawRectangle(0, y, contentWidth, rowHeight, "#E5E7EB", .3f, fill));
-                commands.Add(new DrawStringEx(2 * scale, y + scale, rowHeight - 2 * scale, 31 * scale,
+                commands.Add(new DrawStringEx(2 * scale, y + scale, rowHeight - scale, 31 * scale,
                     row.Date.ToString("dd.MM.yyyy"), DrawingTextAlignment.AlignLeft, 7.5f * scale,
                     Color: "#374151"));
-                commands.Add(new DrawStringEx(36 * scale, y + scale, rowHeight - 2 * scale, 75 * scale,
+                commands.Add(new DrawStringEx(36 * scale, y + scale, rowHeight - scale, 75 * scale,
                     extent, DrawingTextAlignment.AlignLeft, 7.5f * scale, Color: "#374151"));
-                commands.Add(new DrawStringEx(113 * scale, y + scale, rowHeight - 2 * scale, 55 * scale,
+                commands.Add(new DrawStringEx(113 * scale, y + scale, rowHeight - scale, 55 * scale,
                     status, DrawingTextAlignment.AlignLeft, 7.5f * scale, Color: statusColor,
                     Bold: row.IsUnexcused));
                 y += rowHeight;

LehrerApp.Desktop/ViewModels/Students/CreateLetterDialogViewModel.cs

@@ -14,6 +14,7 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     private readonly ITemplateRenderer _renderer;
     private readonly Func<AttendanceCalendarOptions, DrawingValue>? _attendanceCalendarFactory;
     private readonly Func<AttendanceCalendarOptions, DrawingValue>? _absenceDayListFactory;
+    private readonly Func<AttendanceCalendarOptions, CancellationToken, Task>? _attendanceDataRefresher;
     private AttendanceCalendarOptions _attendanceCalendarOptions = new(
         new DateOnly(DateTime.Today.Year, DateTime.Today.Month, 1), 1);
 
@@ -21,6 +22,7 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     [ObservableProperty] private LetterContactChoice? _selectedContact;
     [ObservableProperty] private LetterGroupChoice? _selectedGroup;
     [ObservableProperty] private DateTimeOffset? _letterDate = DateTimeOffset.Now;
+    [ObservableProperty] private string _anrede = "";
     [ObservableProperty] private string _letterText = "";
     [ObservableProperty] private string _teacherName = "";
     [ObservableProperty] private string _generationError = "";
@@ -29,6 +31,8 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     [ObservableProperty] private bool _usesAbsenceDayList;
     [ObservableProperty] private bool _attendanceCalendarConfigured;
     [ObservableProperty] private string _attendanceCalendarSummary = "1 Monat · Standardgröße";
+    [ObservableProperty] private bool _isRefreshingAttendanceData;
+    [ObservableProperty] private string _attendanceRefreshError = "";
 
     public string StudentName => _student.FullName;
     public ObservableCollection<LetterTemplateChoice> Templates { get; } = [];
@@ -47,11 +51,13 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     public CreateLetterDialogViewModel(Student student, TemplateStore templates, ITemplateRenderer renderer,
         IGroupMembershipRepository memberships, IGroupRepository groups,
         Func<AttendanceCalendarOptions, DrawingValue>? attendanceCalendarFactory = null,
-        Func<AttendanceCalendarOptions, DrawingValue>? absenceDayListFactory = null)
+        Func<AttendanceCalendarOptions, DrawingValue>? absenceDayListFactory = null,
+        Func<AttendanceCalendarOptions, CancellationToken, Task>? attendanceDataRefresher = null)
     {
         _student = student; _templates = templates; _renderer = renderer;
         _attendanceCalendarFactory = attendanceCalendarFactory;
         _absenceDayListFactory = absenceDayListFactory;
+        _attendanceDataRefresher = attendanceDataRefresher;
         foreach (var template in templates.GetTemplates()) Templates.Add(new(template));
         foreach (var contact in student.Contacts.Where(c => !c.InvalidSince.HasValue).OrderBy(c => c.Name)) Contacts.Add(new(contact));
         foreach (var membership in memberships.GetByStudent(student.Id))
@@ -73,7 +79,12 @@ public partial class CreateLetterDialogViewModel : ObservableObject
         RebuildCustomPlaceholders(value);
         RefreshValidation();
     }
-    partial void OnSelectedContactChanged(LetterContactChoice? value) => RefreshValidation();
+    partial void OnSelectedContactChanged(LetterContactChoice? value)
+    {
+        Anrede = value?.Model.LetterSalutation ?? "";
+        RefreshValidation();
+    }
+    partial void OnAnredeChanged(string value) => RefreshValidation();
     partial void OnSelectedGroupChanged(LetterGroupChoice? value) => RefreshValidation();
     partial void OnLetterDateChanged(DateTimeOffset? value)
     {
@@ -127,6 +138,7 @@ public partial class CreateLetterDialogViewModel : ObservableObject
             DateOnly.FromDateTime((LetterDate ?? DateTimeOffset.Now).LocalDateTime), LetterText, TeacherName,
             UsesAttendanceCalendar ? _attendanceCalendarFactory?.Invoke(_attendanceCalendarOptions) : null,
             UsesAbsenceDayList ? _absenceDayListFactory?.Invoke(_attendanceCalendarOptions) : null);
+        values["Anrede"] = new TextValue(Anrede); values["Letter.Salutation"] = new TextValue(Anrede);
         foreach (var custom in CustomPlaceholders) values[custom.Name] = custom.ToPlaceholderValue();
         return values;
     }
@@ -159,19 +171,28 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     private static readonly HashSet<string> StandardPlaceholderNames = new(StringComparer.Ordinal)
     {
         "Datum", "CurrentDate", "Empfaenger", "Anrede", "Brieftext", "LehrerName",
-        "Student.FirstName", "Student.LastName", "Contact.Name", "Contact.Address", "Contact.Street",
+        "Student.FirstName", "Student.LastName", "Student.Name", "Contact.Name", "Contact.Address", "Contact.Street",
         "Contact.PostalCode", "Contact.City", "Letter.Salutation", "Group.Name", "SchoolYear",
         StudentAttendanceCalendarDrawingBuilder.PlaceholderName, StudentAbsenceDayListDrawingBuilder.PlaceholderName,
     };
 
     public AttendanceCalendarOptions GetAttendanceCalendarOptions() => _attendanceCalendarOptions;
 
-    public void SetAttendanceCalendarOptions(AttendanceCalendarOptions options)
+    public async Task SetAttendanceCalendarOptionsAsync(AttendanceCalendarOptions options, CancellationToken token = default)
     {
         _attendanceCalendarOptions = options with { StartMonth = options.NormalizedStartMonth,
             MonthCount = options.NormalizedMonthCount };
         AttendanceCalendarConfigured = true;
         AttendanceCalendarSummary = FormatAttendanceCalendarSummary(_attendanceCalendarOptions);
+        AttendanceRefreshError = "";
+        if (_attendanceDataRefresher is not null)
+        {
+            IsRefreshingAttendanceData = true;
+            try { await _attendanceDataRefresher(_attendanceCalendarOptions, token); }
+            catch (WebUntisIntegrationException ex)
+            { AttendanceRefreshError = $"WebUntis-Daten konnten nicht aktualisiert werden: {ex.Message}"; }
+            finally { IsRefreshingAttendanceData = false; }
+        }
         RefreshValidation();
     }
 

LehrerApp.Desktop/Views/Students/CreateLetterDialog.axaml

@@ -32,6 +32,10 @@
           <TextBlock Text="Kein aktueller Kontakt vorhanden." Classes="emptyhint"
                      IsVisible="{Binding HasNoContacts}"/>
         </StackPanel>
+        <StackPanel Spacing="4">
+          <TextBlock Text="Anrede *" FontSize="12" Opacity="0.7"/>
+          <TextBox Text="{Binding Anrede}" PlaceholderText="z.B. Sehr geehrte Frau Mustermann,"/>
+        </StackPanel>
         <Grid ColumnDefinitions="*,12,*">
           <StackPanel Grid.Column="0" Spacing="4">
             <TextBlock Text="Lerngruppe" FontSize="12" Opacity="0.7"/>
@@ -46,14 +50,20 @@
         </Grid>
         <Border IsVisible="{Binding UsesAttendanceAdvancedContent}" BorderBrush="{DynamicResource AppCardBorderBrush}"
                 BorderThickness="1" CornerRadius="6" Padding="12">
-          <Grid ColumnDefinitions="*,Auto">
+          <StackPanel Spacing="6">
-            <StackPanel Spacing="3">
+            <Grid ColumnDefinitions="*,Auto">
-              <TextBlock Text="Anwesenheitsdaten im Brief" FontWeight="SemiBold"/>
+              <StackPanel Spacing="3">
-              <TextBlock Text="{Binding AttendanceCalendarSummary}" FontSize="12" Opacity="0.65"/>
+                <TextBlock Text="Anwesenheitsdaten im Brief" FontWeight="SemiBold"/>
-            </StackPanel>
+                <TextBlock Text="{Binding AttendanceCalendarSummary}" FontSize="12" Opacity="0.65"/>
-            <Button Grid.Column="1" Content="Konfigurieren …" Click="OnConfigureAttendanceCalendar"
+              </StackPanel>
-                    VerticalAlignment="Center"/>
+              <Button Grid.Column="1" Content="Konfigurieren …" Click="OnConfigureAttendanceCalendar"
-          </Grid>
+                      IsEnabled="{Binding !IsRefreshingAttendanceData}" VerticalAlignment="Center"/>
+            </Grid>
+            <TextBlock Text="Aktualisiere WebUntis-Daten für den gewählten Zeitraum …" FontSize="12"
+                       Foreground="#6B7280" IsVisible="{Binding IsRefreshingAttendanceData}"/>
+            <TextBlock Text="{Binding AttendanceRefreshError}" FontSize="12" Foreground="#D97706" TextWrapping="Wrap"
+                       IsVisible="{Binding AttendanceRefreshError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+          </StackPanel>
         </Border>
         <StackPanel Spacing="4">
           <TextBlock Text="Brieftext" FontSize="12" Opacity="0.7"/>

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

@@ -35,7 +35,7 @@ public partial class CreateLetterDialog : Window
         var configVm = new AttendanceCalendarConfigurationViewModel(vm.GetAttendanceCalendarOptions());
         var dialog = new AttendanceCalendarConfigurationDialog { DataContext = configVm };
         if (!await dialog.ShowDialog<bool>(this)) return false;
-        vm.SetAttendanceCalendarOptions(configVm.BuildResult());
+        await vm.SetAttendanceCalendarOptionsAsync(configVm.BuildResult());
         return true;
     }