feat: Fehlzeiten Calender

LehrerApp.Desktop.Tests/ClassTeacherViewModelsTests.cs

@@ -2,6 +2,7 @@ using LehrerApp.Core.Models;
 using LehrerApp.Core.Services;
 using LehrerApp.Desktop.Services;
 using LehrerApp.Desktop.ViewModels.ClassTeacher;
+using LehrerApp.Templating;
 using Xunit;
 
 namespace LehrerApp.Desktop.Tests;
@@ -71,6 +72,61 @@ public sealed class ClassTeacherViewModelsTests
         Assert.False(days[4].HasSignal); // Hausaufgaben bleiben im Widget bewusst ausgeblendet
     }
 
+    [Fact]
+    public void Kompaktkalender_KannAufEinzelnenSchuelerEingeschraenktWerden()
+    {
+        var month = new DateOnly(2026, 9, 1);
+        var absences = new[]
+        {
+            new ClassAbsenceDaySummaryRow(new DateOnly(2026, 9, 3), "Müller Ada", 1, 2, 90,
+                ["Deu"], [1, 2], ["nicht entsch."], ["Absent"], null, null, false),
+            new ClassAbsenceDaySummaryRow(new DateOnly(2026, 9, 4), "Schmidt Ben", 2, 2, 90,
+                ["Mathe"], [1, 2], ["entsch."], ["Absent"], null, null, false),
+        };
+
+        var days = ClassTeacherOverviewViewModel.BuildCompactMonthDays(month, absences, [], month,
+            "Ada Müller");
+
+        Assert.Equal("U", days[2].SignalCode);
+        Assert.False(days[3].HasSignal);
+    }
+
+    [Fact]
+    public void ElternbriefKalender_LiefertPortablenDrawingPlatzhalterFuerSchueler()
+    {
+        var month = new DateOnly(2026, 9, 1);
+        var absences = new[]
+        {
+            new ClassAbsenceDaySummaryRow(new DateOnly(2026, 9, 3), "Müller Ada", 1, 2, 90,
+                ["Deu"], [1, 2], ["nicht entsch."], ["Absent"], null, null, false),
+            new ClassAbsenceDaySummaryRow(new DateOnly(2026, 9, 4), "Schmidt Ben", 2, 2, 90,
+                ["Mathe"], [1, 2], ["entsch."], ["Absent"], null, null, false),
+        };
+
+        var drawing = StudentAttendanceCalendarDrawingBuilder.Build("Ada Müller", month, absences, []);
+
+        Assert.True(drawing.ContentHeight > 0);
+        Assert.Contains(drawing.Commands.OfType<DrawStringEx>(), c => c.Text == "Ada Müller");
+        Assert.Contains(drawing.Commands.OfType<DrawStringEx>(), c => c.Text == "U");
+        Assert.DoesNotContain(drawing.Commands.OfType<DrawStringEx>(), c => c.Text == "E");
+    }
+
+    [Fact]
+    public void ElternbriefKalender_UnterstuetztEinBisDreiMonateUndGroessen()
+    {
+        var start = new DateOnly(2026, 9, 18);
+        var small = StudentAttendanceCalendarDrawingBuilder.Build("Ada Müller",
+            new AttendanceCalendarOptions(start, 3, AttendanceCalendarSize.Small), [], []);
+        var large = StudentAttendanceCalendarDrawingBuilder.Build("Ada Müller",
+            new AttendanceCalendarOptions(start, 3, AttendanceCalendarSize.Large), [], []);
+        var labels = large.Commands.OfType<DrawStringEx>().Select(c => c.Text).ToList();
+
+        Assert.Contains("September 2026", labels);
+        Assert.Contains("Oktober 2026", labels);
+        Assert.Contains("November 2026", labels);
+        Assert.True(large.ContentHeight > small.ContentHeight);
+    }
+
     [Fact]
     public void GroupByStudentAndDay_FasstFehlstundenProSchuelerUndTagZusammen()
     {

LehrerApp.Desktop.Tests/CreateLetterDialogViewModelTests.cs

@@ -1,4 +1,5 @@
 using LehrerApp.Core.Models;
+using LehrerApp.Desktop.Services;
 using LehrerApp.Desktop.ViewModels.Students;
 using LehrerApp.Templating;
 using Xunit;
@@ -54,6 +55,27 @@ public sealed class CreateLetterDialogViewModelTests : IDisposable
         Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
     }
 
+    [Fact]
+    public void AdvancedContent_Anwesenheitskalender_WirdAlsDrawingGerendert()
+    {
+        var store = StoreWithTemplate(new PlaceholderDefinition(
+            StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
+        var drawing = StudentAttendanceCalendarDrawingBuilder.Build("Lena Beispiel", new DateOnly(2026, 9, 1), [], []);
+        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
+            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]), _ => drawing);
+        var output = Path.Combine(_directory, "Kalender.pdf");
+
+        Assert.True(vm.UsesAttendanceCalendar);
+        vm.SetAttendanceCalendarOptions(new AttendanceCalendarOptions(
+            new DateOnly(2026, 8, 19), 3, AttendanceCalendarSize.Large));
+        Assert.True(vm.AttendanceCalendarConfigured);
+        Assert.Contains("August 2026", vm.AttendanceCalendarSummary);
+        Assert.Contains("3 Monate", vm.AttendanceCalendarSummary);
+        Assert.Contains("Groß", vm.AttendanceCalendarSummary);
+        Assert.True(vm.Generate(output));
+        Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
+    }
+
     private CreateLetterDialogViewModel Build(Student student, TemplateStore store) =>
         new(student, store, new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]));
 
@@ -65,8 +87,18 @@ public sealed class CreateLetterDialogViewModelTests : IDisposable
         var y = 20;
         foreach (var definition in definitions)
         {
-            var element = definition.Type == PlaceholderType.Multiline ? "TEXTBOX" : "TEXT";
-            lines.Add(element == "TEXTBOX" ? $"TEXTBOX 20 {y} 170 80 ${definition.Name}" : $"TEXT 20 {y} ${definition.Name}");
+            var element = definition.Type switch
+            {
+                PlaceholderType.Multiline => "TEXTBOX",
+                PlaceholderType.Drawing => "DRAWBOX",
+                _ => "TEXT",
+            };
+            lines.Add(element switch
+            {
+                "TEXTBOX" => $"TEXTBOX 20 {y} 170 80 ${definition.Name}",
+                "DRAWBOX" => $"DRAWBOX 20 {y} 170 80 ${definition.Name}",
+                _ => $"TEXT 20 {y} ${definition.Name}",
+            });
             y += 20;
         }
         TemplatePackage.Create(source, manifest, string.Join('\n', lines), new Dictionary<string, byte[]>());

LehrerApp.Desktop/AppBootstrapper.cs

@@ -229,6 +229,7 @@ public static class AppBootstrapper
         services.AddSingleton<LessonPlanTools>();
         services.AddSingleton<GroupMembershipTools>();
         services.AddSingleton<LetterTemplateTools>();
+        services.AddSingleton<StudentAttendanceCalendarService>();
         services.AddSingleton<CompetencyTools>();
         services.AddSingleton<GroupTools>();
         services.AddSingleton<UntisComparisonTools>();

LehrerApp.Desktop/Services/LetterDialogs.cs

@@ -19,7 +19,8 @@ public static class LetterDialogs
             App.Services.GetRequiredService<TemplateStore>(),
             App.Services.GetRequiredService<ITemplateRenderer>(),
             App.Services.GetRequiredService<IGroupMembershipRepository>(),
-            App.Services.GetRequiredService<IGroupRepository>());
+            App.Services.GetRequiredService<IGroupRepository>(),
+            options => App.Services.GetRequiredService<StudentAttendanceCalendarService>().Build(student, options));
         var dialog = new CreateLetterDialog { DataContext = vm };
         var path = await dialog.ShowDialog<string?>(owner);
         if (!string.IsNullOrEmpty(path) && File.Exists(path))

LehrerApp.Desktop/Services/LetterPlaceholderBuilder.cs

@@ -15,7 +15,7 @@ public static class LetterPlaceholderBuilder
 {
     public static Dictionary<string, PlaceholderValue> BuildStandardValues(
         Student student, Contact? contact, LearningGroup? group, DateOnly date,
-        string letterText, string teacherName)
+        string letterText, string teacherName, DrawingValue? attendanceCalendar = null)
     {
         var cityLine = string.Join(" ", new[] { contact?.PostalCode, contact?.City }.Where(x => !string.IsNullOrWhiteSpace(x)));
         var address = string.Join(Environment.NewLine, new[] { contact?.Name, contact?.Street, cityLine }.Where(x => !string.IsNullOrWhiteSpace(x)));
@@ -29,6 +29,7 @@ public static class LetterPlaceholderBuilder
             ["Contact.Street"] = new TextValue(contact?.Street ?? ""), ["Contact.PostalCode"] = new TextValue(contact?.PostalCode ?? ""),
             ["Contact.City"] = new TextValue(contact?.City ?? ""), ["Letter.Salutation"] = new TextValue(contact?.LetterSalutation ?? ""),
             ["Group.Name"] = new TextValue(group?.Name ?? ""), ["SchoolYear"] = new TextValue(group?.SchoolYear ?? ""),
+            [StudentAttendanceCalendarDrawingBuilder.PlaceholderName] = attendanceCalendar ?? new DrawingValue([], 0),
         };
     }
 
@@ -36,6 +37,7 @@ public static class LetterPlaceholderBuilder
     {
         TextValue x => string.IsNullOrWhiteSpace(x.Value),
         MultilineValue x => string.IsNullOrWhiteSpace(x.Value),
+        DrawingValue x => x.ContentHeight <= 0 || x.Commands.Count == 0,
         _ => false,
     };
 }

LehrerApp.Desktop/Services/Mcp/Tools/LetterTemplateTools.cs

@@ -19,7 +19,8 @@ namespace LehrerApp.Desktop.Services.Mcp.Tools;
 /// tatsächlich nützlichen Fall ab: eine bestehende, vom Nutzer gestaltete Vorlage mit Werten füllen.</summary>
 public class LetterTemplateTools(
     TemplateStore templates, ITemplateLoader loader, ITemplateRenderer renderer,
-    IStudentRepository students, IGroupRepository groups)
+    IStudentRepository students, IGroupRepository groups,
+    StudentAttendanceCalendarService? attendanceCalendars = null)
 {
     [Description("Listet importierte Elternbrief-Vorlagen mit ihren deklarierten Platzhaltern (Name, Typ, Pflichtfeld, konstant).")]
     public List<LetterTemplateDto> ListLetterTemplates()
@@ -73,7 +74,8 @@ public class LetterTemplateTools(
         var group = groupId is { } gid ? groups.GetById(gid) : null;
         var date = letterDate ?? DateOnly.FromDateTime(DateTime.Today);
 
-        var values = LetterPlaceholderBuilder.BuildStandardValues(student, contact, group, date, letterText, teacherName);
+        var values = LetterPlaceholderBuilder.BuildStandardValues(student, contact, group, date, letterText,
+            teacherName, attendanceCalendars?.Build(student, date));
         foreach (var (name, raw) in extraValues ?? [])
         {
             var definition = loaded.Manifest.Placeholders.FirstOrDefault(p => p.Name == name);

LehrerApp.Desktop/Services/StudentAttendanceCalendarDrawingBuilder.cs

@@ -0,0 +1,129 @@
+using System.Globalization;
+using LehrerApp.Core.Interfaces;
+using LehrerApp.Core.Models;
+using LehrerApp.Desktop.ViewModels.ClassTeacher;
+using LehrerApp.Templating;
+
+namespace LehrerApp.Desktop.Services;
+
+public enum AttendanceCalendarSize { Small, Medium, Large }
+
+public sealed record AttendanceCalendarOptions(DateOnly StartMonth, int MonthCount,
+    AttendanceCalendarSize Size = AttendanceCalendarSize.Medium)
+{
+    public DateOnly NormalizedStartMonth => new(StartMonth.Year, StartMonth.Month, 1);
+    public int NormalizedMonthCount => Math.Clamp(MonthCount, 1, 3);
+}
+
+/// <summary>Erzeugt den portablen Advanced-Content-Platzhalter für Elternbriefe aus derselben
+/// priorisierten Monatsansicht, die im Klassenlehrer-Sidebar-Widget verwendet wird.</summary>
+public static class StudentAttendanceCalendarDrawingBuilder
+{
+    public const string PlaceholderName = "Student.AttendanceCalendar";
+
+    public static DrawingValue Build(string studentName, DateOnly month,
+        IReadOnlyList<ClassAbsenceDaySummaryRow> absences,
+        IReadOnlyList<UntisForeignClassRegisterEventDto> registerEntries) =>
+        Build(studentName, new AttendanceCalendarOptions(month, 1), absences, registerEntries);
+
+    public static DrawingValue Build(string studentName, AttendanceCalendarOptions options,
+        IReadOnlyList<ClassAbsenceDaySummaryRow> absences,
+        IReadOnlyList<UntisForeignClassRegisterEventDto> registerEntries)
+    {
+        const float width = 170;
+        var scale = options.Size switch
+        {
+            AttendanceCalendarSize.Small => .7f,
+            AttendanceCalendarSize.Large => 1f,
+            _ => .85f,
+        };
+        var contentWidth = width * scale;
+        var cellWidth = contentWidth / 7;
+        var cellHeight = 10 * scale;
+        var monthGap = 6 * scale;
+        var first = options.NormalizedStartMonth;
+        var monthCount = options.NormalizedMonthCount;
+        var commands = new List<DrawingCommand>
+        {
+            new DrawStringEx(0, 0, 7 * scale, contentWidth, "Anwesenheit",
+                DrawingTextAlignment.AlignLeft, 11 * scale, Color: "#1F2937", Bold: true),
+            new DrawStringEx(0, 7 * scale, 6 * scale, contentWidth, studentName,
+                DrawingTextAlignment.AlignLeft, 8 * scale, Color: "#6B7280"),
+        };
+        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);
+            var days = ClassTeacherOverviewViewModel.BuildCompactMonthDays(current, absences, registerEntries,
+                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,
+                current.ToString("MMMM yyyy", CultureInfo.GetCultureInfo("de-DE")),
+                DrawingTextAlignment.AlignLeft, 9 * scale, Color: "#374151", Bold: true));
+            y += 7 * scale;
+            for (var column = 0; column < 7; column++)
+                commands.Add(new DrawStringEx(column * cellWidth, y, 6 * scale, cellWidth, weekdays[column],
+                    DrawingTextAlignment.AlignCenter, 7 * scale, Color: "#6B7280", Bold: true));
+            y += 7 * scale;
+
+            foreach (var day in days)
+            {
+                var index = offset + day.Date.Day - 1;
+                var column = index % 7;
+                var row = index / 7;
+                var x = column * cellWidth;
+                var cellY = y + row * cellHeight;
+                commands.Add(new DrawRectangle(x + scale, cellY, cellWidth - 2 * scale, cellHeight - scale,
+                    "#D1D5DB", .35f, day.HasSignal ? day.SignalColorHex : "#FFFFFF"));
+                commands.Add(new DrawStringEx(x, cellY + scale, cellHeight - 2 * scale, cellWidth,
+                    day.HasSignal ? day.SignalCode : day.DayNumber, DrawingTextAlignment.AlignCenter, 7 * scale,
+                    Color: day.HasSignal ? "#FFFFFF" : "#374151", Bold: day.HasSignal));
+            }
+            y += weeks * cellHeight + monthGap;
+        }
+
+        commands.Add(new DrawStringEx(0, y, 8 * scale, contentWidth,
+            "U unentschuldigt · A abwesend · V verspätet · E entschuldigt · ! Klassenbuch",
+            DrawingTextAlignment.AlignLeft, 6.5f * scale, Color: "#6B7280"));
+        return new DrawingValue(commands, y + 9 * scale);
+    }
+}
+
+/// <summary>Liest ausschließlich den lokalen WebUntis-Cache. Das Öffnen oder Rendern eines
+/// Elternbriefs löst dadurch keinen unerwarteten Netzwerkabruf aus.</summary>
+public sealed class StudentAttendanceCalendarService(
+    WebUntisSettingsService settings,
+    IUntisAbsenceCacheRepository absenceCache,
+    IUntisClassRegisterCacheRepository registerCache,
+    IUntisStudentRosterCacheRepository rosterCache)
+{
+    public DrawingValue Build(Student student, DateOnly month) =>
+        Build(student, new AttendanceCalendarOptions(month, 1));
+
+    public DrawingValue Build(Student student, AttendanceCalendarOptions options)
+    {
+        var className = settings.HomeroomClassName;
+        if (string.IsNullOrWhiteSpace(className)) return new DrawingValue([], 0);
+
+        var first = options.NormalizedStartMonth;
+        var last = first.AddMonths(options.NormalizedMonthCount).AddDays(-1);
+        var rosterName = rosterCache.GetByClass(className)
+            .FirstOrDefault(r => UntisNameMatching.NamesMatch(r.DisplayName, student.FullName))?.DisplayName
+            ?? student.FullName;
+        var start = first.Year * 10000 + first.Month * 100 + first.Day;
+        var end = last.Year * 10000 + last.Month * 100 + last.Day;
+        var absences = absenceCache.GetByClassAndRange(className, start, end)
+            .Select(e => new UntisClassAbsenceEntryDto(e.StudentName, e.ExternKey, e.ClassName, e.Date,
+                e.AbsentPeriods, e.AbsentMinutes, e.TeacherUsernames, e.Subject, e.AbsenceReason, e.Note,
+                e.EntryId, e.HandledOn, e.Counts, e.ExcuseNote, e.PeriodNumber, e.Status, e.CountsAsFullDay))
+            .ToList();
+        var register = registerCache.GetByClassAndRange(className, start, end)
+            .Select(e => new UntisForeignClassRegisterEventDto(e.ClassName, e.Date, e.Subject, e.StudentName,
+                e.TeacherUsername, e.CategoryName, e.CategoryGroup, e.Text))
+            .ToList();
+        return StudentAttendanceCalendarDrawingBuilder.Build(rosterName, options,
+            ClassAbsenceDaySummaryRow.GroupByStudentAndDay(absences), register);
+    }
+}

LehrerApp.Desktop/ViewModels/ClassTeacher/ClassTeacherOverviewViewModel.cs

@@ -18,6 +18,10 @@ public enum ClassTeacherStatusKind { Ok, Info, Warning, Danger }
 /// Schlagwort gezielt dämpfen kann, siehe <see cref="ClassTeacherRosterRow.MatchDomains"/>.</summary>
 public enum VorgangScoreDomain { Attendance, Lateness, Classbook }
 
+/// <summary>Auswahlbereich des kompakten Monatskalenders. Ein leerer Schülername steht für die
+/// bisherige Klassen-Gesamtansicht.</summary>
+public sealed record ClassTeacherCalendarScope(string? StudentName, string DisplayName);
+
 public sealed record ClassTeacherRosterRow(string StudentName, int? ExternKey, bool HasAbsenceToday,
     string? AbsenceTooltip, bool HasRecentClassRegisterEntry)
 {
@@ -424,6 +428,7 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     public ObservableCollection<ClassTeacherPatternNotice> PatternNotices { get; } = [];
     public ObservableCollection<ClassTeacherOpenExcuseRow> OpenExcuses { get; } = [];
     public ObservableCollection<ClassTeacherCompactCalendarDay> CompactMonthDays { get; } = [];
+    public ObservableCollection<ClassTeacherCalendarScope> CalendarScopes { get; } = [];
 
     [ObservableProperty] private string? _homeroomClassName;
     [ObservableProperty] private int _activeTabIndex;
@@ -453,6 +458,7 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     /// den "Klassenbuch öffnen"-Button gehängt statt in einer eigenen Kennzahlkarte.
     [ObservableProperty] private int _ownDocumentationFollowUpCount;
     [ObservableProperty] private int _ownDocumentationCriticalCount;
+    [ObservableProperty] private ClassTeacherCalendarScope? _selectedCalendarScope;
 
     // Zuletzt per Load() geholte WebUntis-Rohdaten, für RefreshFromLocalDataOnly() - damit ein
     // eingehendes Sync-Ereignis die Ansicht neu aufbauen kann, ohne selbst WebUntis anzufragen.
@@ -501,8 +507,17 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     public double UnexcusedAbsenceFraction => StudentCount == 0 ? 0 : (double)UnexcusedAbsenceCount / StudentCount;
     public string DayOverviewTooltip => $"{PresentCount} anwesend · {LateCount} verspätet · " +
         $"{ExcusedAbsenceCount} entschuldigt · {UnexcusedAbsenceCount} unentschuldigt";
-    public string CompactMonthLabel => DateOnly.FromDateTime(DateTime.Today).ToString("MMMM yyyy",
+    public string CompactMonthLabel
+    {
+        get
+        {
+            var month = DateOnly.FromDateTime(DateTime.Today).ToString("MMMM yyyy",
                 System.Globalization.CultureInfo.GetCultureInfo("de-DE"));
+            return SelectedCalendarScope?.StudentName is { Length: > 0 }
+                ? $"{month} · {SelectedCalendarScope.DisplayName}"
+                : $"{month} · gesamte Klasse";
+        }
+    }
 
     public Func<Task>? OnNavigateToSettings { get; set; }
     public Func<Task>? OnNavigateToWorkload { get; set; }
@@ -534,6 +549,11 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     partial void OnOpenExcuseOverflowCountChanged(int value) => OnPropertyChanged(nameof(HasOpenExcuseOverflow));
     partial void OnOwnDocumentationFollowUpCountChanged(int value) => OnPropertyChanged(nameof(HasOwnDocumentationAlerts));
     partial void OnOwnDocumentationCriticalCountChanged(int value) => OnPropertyChanged(nameof(HasOwnDocumentationAlerts));
+    partial void OnSelectedCalendarScopeChanged(ClassTeacherCalendarScope? value)
+    {
+        OnPropertyChanged(nameof(CompactMonthLabel));
+        if (CalendarScopes.Count > 0) RebuildCompactMonthFromCachedData();
+    }
     partial void OnSearchTextChanged(string value) => ApplyRosterFilter();
     partial void OnSelectedRosterFilterChanged(int value)
     {
@@ -548,7 +568,8 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     {
         ActiveTabIndex = 0;
         Roster.Clear(); PrimaryRoster.Clear(); SecondaryRoster.Clear(); TrendDays.Clear(); PatternNotices.Clear();
-        OpenExcuses.Clear(); CompactMonthDays.Clear(); OpenExcuseOverflowCount = 0;
+        OpenExcuses.Clear(); CompactMonthDays.Clear(); CalendarScopes.Clear(); SelectedCalendarScope = null;
+        OpenExcuseOverflowCount = 0;
     }
 
     // Wird beim Navigieren auf diese Seite aufgerufen statt LoadCommand: baut nur den lokalen
@@ -678,6 +699,12 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
                      holidayWeekdaysExcluded, termStart, classRegisterEvents,
                      _patternScoreSettings.Load(), closedVorgaengeByNameKey)) Roster.Add(row);
 
+        CalendarScopes.Add(new ClassTeacherCalendarScope(null, "Gesamte Klasse"));
+        foreach (var student in students.OrderBy(s => s.DisplayName))
+            CalendarScopes.Add(new ClassTeacherCalendarScope(student.DisplayName,
+                ClassTeacherOverviewViewModel.DisplayStudentName(student.DisplayName)));
+        SelectedCalendarScope = CalendarScopes[0];
+
         StudentCount = Roster.Count;
         TodayAlertCount = Roster.Count(r => r.HasAbsenceToday);
         TodayUnexcusedCount = Roster.Count(r => r.IsUnexcused);
@@ -724,7 +751,7 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     private void OpenMonthlyCalendar()
     {
         var today = DateOnly.FromDateTime(DateTime.Today);
-        DetailsTab.StudentFilter = "";
+        DetailsTab.StudentFilter = SelectedCalendarScope?.StudentName ?? "";
         DetailsTab.CalendarMonth = new DateOnly(today.Year, today.Month, 1);
         ActiveTabIndex = 2;
         DetailsTab.ShowCalendarCommand.Execute(null);
@@ -735,15 +762,29 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     {
         CompactMonthDays.Clear();
         foreach (var day in BuildCompactMonthDays(new DateOnly(today.Year, today.Month, 1),
-                     absences, registerEntries, today))
+                     absences, registerEntries, today, SelectedCalendarScope?.StudentName))
             CompactMonthDays.Add(day);
     }
 
+    private void RebuildCompactMonthFromCachedData()
+    {
+        if (_lastAbsences is null || _lastClassRegisterEvents is null) return;
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        BuildCompactMonth(ClassAbsenceDaySummaryRow.GroupByStudentAndDay(_lastAbsences),
+            _lastClassRegisterEvents, today);
+    }
+
     public static IReadOnlyList<ClassTeacherCompactCalendarDay> BuildCompactMonthDays(DateOnly month,
         IReadOnlyList<ClassAbsenceDaySummaryRow> absences,
-        IReadOnlyList<UntisForeignClassRegisterEventDto> registerEntries, DateOnly today)
+        IReadOnlyList<UntisForeignClassRegisterEventDto> registerEntries, DateOnly today,
+        string? studentName = null)
     {
         var first = new DateOnly(month.Year, month.Month, 1);
+        if (!string.IsNullOrWhiteSpace(studentName))
+        {
+            absences = absences.Where(a => UntisNameMatching.NamesMatch(a.StudentName, studentName)).ToList();
+            registerEntries = registerEntries.Where(e => UntisNameMatching.NamesMatch(e.StudentName, studentName)).ToList();
+        }
         var registerRows = registerEntries
             .Select(e => (Entry: e, Valid: TryDate(e.Date, out var date), Date: date))
             .Where(x => x.Valid && x.Date.Year == first.Year && x.Date.Month == first.Month)
@@ -768,6 +809,12 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
         return result;
     }
 
+    internal static string DisplayStudentName(string value)
+    {
+        var parts = value.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+        return parts.Length < 2 ? value : string.Join(" ", parts.Skip(1).Append(parts[0]));
+    }
+
     private static int SignalPriority(ClassTeacherCalendarEventKind kind) => kind switch
     {
         ClassTeacherCalendarEventKind.Unexcused => 0,

LehrerApp.Desktop/ViewModels/Students/AttendanceCalendarConfigurationViewModel.cs

@@ -0,0 +1,35 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using LehrerApp.Desktop.Services;
+
+namespace LehrerApp.Desktop.ViewModels.Students;
+
+public sealed record AttendanceCalendarSizeChoice(AttendanceCalendarSize Value, string DisplayName);
+
+public partial class AttendanceCalendarConfigurationViewModel : ObservableObject
+{
+    [ObservableProperty] private DateTimeOffset? _startMonth;
+    [ObservableProperty] private int _monthCount;
+    [ObservableProperty] private AttendanceCalendarSizeChoice _selectedSize;
+
+    public IReadOnlyList<int> MonthCounts { get; } = [1, 2, 3];
+    public IReadOnlyList<AttendanceCalendarSizeChoice> Sizes { get; } =
+    [
+        new(AttendanceCalendarSize.Small, "Klein"),
+        new(AttendanceCalendarSize.Medium, "Standard"),
+        new(AttendanceCalendarSize.Large, "Groß"),
+    ];
+
+    public AttendanceCalendarConfigurationViewModel(AttendanceCalendarOptions options)
+    {
+        StartMonth = new DateTimeOffset(options.NormalizedStartMonth.ToDateTime(TimeOnly.MinValue));
+        MonthCount = options.NormalizedMonthCount;
+        SelectedSize = Sizes.First(s => s.Value == options.Size);
+    }
+
+    public AttendanceCalendarOptions BuildResult()
+    {
+        var date = DateOnly.FromDateTime((StartMonth ?? DateTimeOffset.Now).LocalDateTime);
+        return new AttendanceCalendarOptions(new DateOnly(date.Year, date.Month, 1), MonthCount,
+            SelectedSize.Value);
+    }
+}

LehrerApp.Desktop/ViewModels/Students/CreateLetterDialogViewModel.cs

@@ -12,6 +12,9 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     private readonly Student _student;
     private readonly TemplateStore _templates;
     private readonly ITemplateRenderer _renderer;
+    private readonly Func<AttendanceCalendarOptions, DrawingValue>? _attendanceCalendarFactory;
+    private AttendanceCalendarOptions _attendanceCalendarOptions = new(
+        new DateOnly(DateTime.Today.Year, DateTime.Today.Month, 1), 1);
 
     [ObservableProperty] private LetterTemplateChoice? _selectedTemplate;
     [ObservableProperty] private LetterContactChoice? _selectedContact;
@@ -21,6 +24,9 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     [ObservableProperty] private string _teacherName = "";
     [ObservableProperty] private string _generationError = "";
     [ObservableProperty] private bool _canGenerate;
+    [ObservableProperty] private bool _usesAttendanceCalendar;
+    [ObservableProperty] private bool _attendanceCalendarConfigured;
+    [ObservableProperty] private string _attendanceCalendarSummary = "1 Monat · Standardgröße";
 
     public string StudentName => _student.FullName;
     public ObservableCollection<LetterTemplateChoice> Templates { get; } = [];
@@ -34,9 +40,11 @@ public partial class CreateLetterDialogViewModel : ObservableObject
         $"{SelectedTemplate?.Name ?? "Elternbrief"}_{_student.LastName}_{_student.FirstName}.pdf");
 
     public CreateLetterDialogViewModel(Student student, TemplateStore templates, ITemplateRenderer renderer,
-        IGroupMembershipRepository memberships, IGroupRepository groups)
+        IGroupMembershipRepository memberships, IGroupRepository groups,
+        Func<AttendanceCalendarOptions, DrawingValue>? attendanceCalendarFactory = null)
     {
         _student = student; _templates = templates; _renderer = renderer;
+        _attendanceCalendarFactory = attendanceCalendarFactory;
         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))
@@ -45,10 +53,21 @@ public partial class CreateLetterDialogViewModel : ObservableObject
         RefreshValidation();
     }
 
-    partial void OnSelectedTemplateChanged(LetterTemplateChoice? value) { OnPropertyChanged(nameof(SuggestedFileName)); RefreshValidation(); }
+    partial void OnSelectedTemplateChanged(LetterTemplateChoice? value)
+    {
+        OnPropertyChanged(nameof(SuggestedFileName));
+        UsesAttendanceCalendar = TemplateUsesAttendanceCalendar(value);
+        AttendanceCalendarConfigured = false;
+        ResetAttendanceCalendarOptions();
+        RefreshValidation();
+    }
     partial void OnSelectedContactChanged(LetterContactChoice? value) => RefreshValidation();
     partial void OnSelectedGroupChanged(LetterGroupChoice? value) => RefreshValidation();
-    partial void OnLetterDateChanged(DateTimeOffset? value) => RefreshValidation();
+    partial void OnLetterDateChanged(DateTimeOffset? value)
+    {
+        if (!AttendanceCalendarConfigured) ResetAttendanceCalendarOptions();
+        RefreshValidation();
+    }
     partial void OnLetterTextChanged(string value) => RefreshValidation();
     partial void OnTeacherNameChanged(string value) => RefreshValidation();
 
@@ -91,7 +110,60 @@ public partial class CreateLetterDialogViewModel : ObservableObject
 
     private IReadOnlyDictionary<string, PlaceholderValue> BuildValues() => LetterPlaceholderBuilder.BuildStandardValues(
         _student, SelectedContact?.Model, SelectedGroup?.Model,
-        DateOnly.FromDateTime((LetterDate ?? DateTimeOffset.Now).LocalDateTime), LetterText, TeacherName);
+        DateOnly.FromDateTime((LetterDate ?? DateTimeOffset.Now).LocalDateTime), LetterText, TeacherName,
+        UsesAttendanceCalendar ? _attendanceCalendarFactory?.Invoke(_attendanceCalendarOptions) : null);
+
+    public AttendanceCalendarOptions GetAttendanceCalendarOptions() => _attendanceCalendarOptions;
+
+    public void SetAttendanceCalendarOptions(AttendanceCalendarOptions options)
+    {
+        _attendanceCalendarOptions = options with { StartMonth = options.NormalizedStartMonth,
+            MonthCount = options.NormalizedMonthCount };
+        AttendanceCalendarConfigured = true;
+        AttendanceCalendarSummary = FormatAttendanceCalendarSummary(_attendanceCalendarOptions);
+        RefreshValidation();
+    }
+
+    private void ResetAttendanceCalendarOptions()
+    {
+        var date = DateOnly.FromDateTime((LetterDate ?? DateTimeOffset.Now).LocalDateTime);
+        _attendanceCalendarOptions = new AttendanceCalendarOptions(new(date.Year, date.Month, 1), 1);
+        AttendanceCalendarSummary = FormatAttendanceCalendarSummary(_attendanceCalendarOptions);
+    }
+
+    private bool TemplateUsesAttendanceCalendar(LetterTemplateChoice? choice)
+    {
+        if (choice is null) return false;
+        try
+        {
+            var loaded = _templates.Load(choice.Model);
+            return UsesPlaceholder(loaded.Layout) ||
+                   (loaded.ContinuationLayout is not null && UsesPlaceholder(loaded.ContinuationLayout));
+        }
+        catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException)
+        {
+            return false;
+        }
+    }
+
+    private static bool UsesPlaceholder(TemplateLayout layout) =>
+        layout.Elements.Concat(layout.PageTemplates.SelectMany(p => p.Elements))
+            .Concat(layout.ContentFlows.SelectMany(f => f.Elements))
+            .Any(e => e is DrawBoxElement { Placeholder: StudentAttendanceCalendarDrawingBuilder.PlaceholderName }
+                   or FlowDrawBoxElement { Placeholder: StudentAttendanceCalendarDrawingBuilder.PlaceholderName });
+
+    private static string FormatAttendanceCalendarSummary(AttendanceCalendarOptions options)
+    {
+        var month = options.NormalizedStartMonth.ToString("MMMM yyyy",
+            System.Globalization.CultureInfo.GetCultureInfo("de-DE"));
+        var size = options.Size switch
+        {
+            AttendanceCalendarSize.Small => "Klein",
+            AttendanceCalendarSize.Large => "Groß",
+            _ => "Standard",
+        };
+        return $"Ab {month} · {options.NormalizedMonthCount} Monat{(options.NormalizedMonthCount == 1 ? "" : "e")} · {size}";
+    }
 
     private static bool IsEmpty(PlaceholderValue value) => LetterPlaceholderBuilder.IsEmpty(value);
     private static string SanitizeFileName(string value)

LehrerApp.Desktop/Views/ClassTeacher/ClassTeacherOverviewView.axaml

@@ -436,6 +436,11 @@
                               Background="Transparent" BorderThickness="0" Padding="6,2"
                               Foreground="{DynamicResource AppAccentTextBrush}"/>
                     </Grid>
+                    <ComboBox ItemsSource="{Binding CalendarScopes}"
+                              SelectedItem="{Binding SelectedCalendarScope, Mode=TwoWay}"
+                              DisplayMemberBinding="{Binding DisplayName}"
+                              HorizontalAlignment="Stretch"
+                              AutomationProperties.Name="Schüler für Monatskalender auswählen"/>
                     <ItemsControl ItemsSource="{Binding CompactMonthDays}" HorizontalAlignment="Center">
                       <ItemsControl.ItemsPanel>
                         <ItemsPanelTemplate><UniformGrid Columns="7"/></ItemsPanelTemplate>

LehrerApp.Desktop/Views/Students/AttendanceCalendarConfigurationDialog.axaml

@@ -0,0 +1,39 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Students"
+        xmlns:conv="clr-namespace:LehrerApp.Desktop.Converters"
+        x:Class="LehrerApp.Desktop.Views.Students.AttendanceCalendarConfigurationDialog"
+        x:DataType="vm:AttendanceCalendarConfigurationViewModel"
+        Title="Anwesenheitskalender konfigurieren" Width="440" Height="360"
+        CanResize="False" WindowStartupLocation="CenterOwner">
+  <Grid RowDefinitions="*,Auto" Margin="24,20">
+    <StackPanel Spacing="16">
+      <TextBlock Text="Anwesenheitskalender" Classes="dialogtitle"/>
+      <TextBlock Text="Diese Angaben steuern den dynamischen Kalender im Elternbrief. Der Starttag wird automatisch auf den ersten Tag des gewählten Monats gesetzt."
+                 FontSize="12" Opacity="0.65" TextWrapping="Wrap"/>
+      <StackPanel Spacing="4">
+        <TextBlock Text="Erster Monat" FontSize="12" Opacity="0.7"/>
+        <CalendarDatePicker SelectedDate="{Binding StartMonth, Converter={x:Static conv:DateTimeOffsetToDateTimeConverter.Instance}}"
+                            HorizontalAlignment="Stretch"/>
+      </StackPanel>
+      <Grid ColumnDefinitions="*,12,*">
+        <StackPanel Spacing="4">
+          <TextBlock Text="Anzahl Monate" FontSize="12" Opacity="0.7"/>
+          <ComboBox ItemsSource="{Binding MonthCounts}" SelectedItem="{Binding MonthCount, Mode=TwoWay}"
+                    HorizontalAlignment="Stretch"/>
+        </StackPanel>
+        <StackPanel Grid.Column="2" Spacing="4">
+          <TextBlock Text="Darstellungsgröße" FontSize="12" Opacity="0.7"/>
+          <ComboBox ItemsSource="{Binding Sizes}" SelectedItem="{Binding SelectedSize, Mode=TwoWay}"
+                    DisplayMemberBinding="{Binding DisplayName}" HorizontalAlignment="Stretch"/>
+        </StackPanel>
+      </Grid>
+      <TextBlock Text="Bei mehreren Monaten wächst der Zeicheninhalt nach unten. Für drei große Monate sollte die Vorlage eine ausreichend hohe DRAWBOX oder eine FLOWDRAWBOX verwenden."
+                 FontSize="11" Opacity="0.55" TextWrapping="Wrap"/>
+    </StackPanel>
+    <Grid Grid.Row="1" ColumnDefinitions="*,10,*" Margin="0,18,0,0">
+      <Button Grid.Column="0" Content="Abbrechen" HorizontalAlignment="Stretch" Click="OnCancel"/>
+      <Button Grid.Column="2" Content="Übernehmen" HorizontalAlignment="Stretch" Click="OnApply"/>
+    </Grid>
+  </Grid>
+</Window>

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

@@ -0,0 +1,12 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+
+namespace LehrerApp.Desktop.Views.Students;
+
+public partial class AttendanceCalendarConfigurationDialog : Window
+{
+    public AttendanceCalendarConfigurationDialog() => InitializeComponent();
+
+    private void OnApply(object? sender, RoutedEventArgs e) => Close(true);
+    private void OnCancel(object? sender, RoutedEventArgs e) => Close(false);
+}

LehrerApp.Desktop/Views/Students/CreateLetterDialog.axaml

@@ -44,6 +44,17 @@
             <CalendarDatePicker SelectedDate="{Binding LetterDate, Converter={x:Static conv:DateTimeOffsetToDateTimeConverter.Instance}}" HorizontalAlignment="Stretch"/>
           </StackPanel>
         </Grid>
+        <Border IsVisible="{Binding UsesAttendanceCalendar}" BorderBrush="{DynamicResource AppCardBorderBrush}"
+                BorderThickness="1" CornerRadius="6" Padding="12">
+          <Grid ColumnDefinitions="*,Auto">
+            <StackPanel Spacing="3">
+              <TextBlock Text="Anwesenheitskalender im Brief" FontWeight="SemiBold"/>
+              <TextBlock Text="{Binding AttendanceCalendarSummary}" FontSize="12" Opacity="0.65"/>
+            </StackPanel>
+            <Button Grid.Column="1" Content="Konfigurieren …" Click="OnConfigureAttendanceCalendar"
+                    VerticalAlignment="Center"/>
+          </Grid>
+        </Border>
         <StackPanel Spacing="4">
           <TextBlock Text="Brieftext" FontSize="12" Opacity="0.7"/>
           <TextBox Text="{Binding LetterText}" AcceptsReturn="True" TextWrapping="Wrap" MinHeight="110"

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

@@ -12,6 +12,8 @@ public partial class CreateLetterDialog : Window
     private async void OnGenerate(object? sender, RoutedEventArgs e)
     {
         if (DataContext is not CreateLetterDialogViewModel vm) return;
+        if (vm.UsesAttendanceCalendar && !vm.AttendanceCalendarConfigured &&
+            !await ConfigureAttendanceCalendar(vm)) return;
         var file = await StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions
         {
             Title = "PDF-Brief speichern",
@@ -23,5 +25,19 @@ public partial class CreateLetterDialog : Window
         Close(file.Path.LocalPath);
     }
 
+    private async void OnConfigureAttendanceCalendar(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is CreateLetterDialogViewModel vm) await ConfigureAttendanceCalendar(vm);
+    }
+
+    private async Task<bool> ConfigureAttendanceCalendar(CreateLetterDialogViewModel vm)
+    {
+        var configVm = new AttendanceCalendarConfigurationViewModel(vm.GetAttendanceCalendarOptions());
+        var dialog = new AttendanceCalendarConfigurationDialog { DataContext = configVm };
+        if (!await dialog.ShowDialog<bool>(this)) return false;
+        vm.SetAttendanceCalendarOptions(configVm.BuildResult());
+        return true;
+    }
+
     private void OnCancel(object? sender, RoutedEventArgs e) => Close(null);
 }

LehrerApp.TemplateDesigner/DesignerViewModel.cs

@@ -61,6 +61,7 @@ public partial class DesignerViewModel : ObservableObject
         new("Anrede", PlaceholderType.Text, true, "Frau Beispiel"),
         new("Brieftext", PlaceholderType.Multiline, true, "hiermit informieren wir Sie über einen wichtigen Termin.\n\nMit freundlichen Grüßen"),
         new("LehrerName", PlaceholderType.Text, true, "M. Mustermann"),
+        new("Student.AttendanceCalendar", PlaceholderType.Drawing, false, ""),
     ];
     public ObservableCollection<DesignerMetadata> MetadataItems { get; } =
     [