feat: Komfort-Features für Unterrichtsplanung, Zeiterfassung und Dashboard

- Neue-Stunde-Dialog: Datum wird beim Anlegen anhand des Stundenplans
  und der letzten Stunde der Einheit vorbelegt statt auf "heute"
  (behebt eine falsch erkannte Doppelstunde, wenn "heute" nicht auf
  den passenden Wochentag fiel).
- Zeiterfassung: Button "Unterrichtszeit heute übernehmen" schlägt
  Start/Ende aus dem heutigen Stundenplan inkl. Puffer davor/danach vor.
- Dashboard: neue Kachel "Ungeplante Stunden" erinnert an Stunden ohne
  Thema für heute/morgen, mit Opt-out je Gruppe ("Benötigt
  Unterrichtsplanung"), Doppelstunden-Erkennung (keine doppelte Meldung
  für die zweite Periode) und Berücksichtigung von Stundenausfall.

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

LehrerApp.Desktop.Tests/DashboardViewModelTests.cs

@@ -26,14 +26,23 @@ public sealed class DashboardViewModelTests
         return new DashboardSettingsService(tempPath);
     }
 
+    private static SchoolCalendarSettingsService NewCalendarSettings()
+    {
+        var tempPath = System.IO.Path.Combine(
+            System.IO.Path.GetTempPath(), $"lehrerapp-schoolcalendar-tests-{Guid.NewGuid():N}");
+        Directory.CreateDirectory(tempPath);
+        return new SchoolCalendarSettingsService(tempPath);
+    }
+
     private static DashboardViewModel BuildVm(LearningGroup group, Lesson lesson,
         FakeTimetableSlots? slots = null, PeriodScheduleService? periodSchedule = null,
         FakeExams? exams = null, FakeResults? results = null, FakeGrades? grades = null,
         FakeReportGrades? reportGrades = null, FakeMemberships? memberships = null,
         FakeWorkTasks? tasks = null, FakeStudents? students = null, FakeDocumentation? documentation = null,
-        DashboardSettingsService? dashboardSettings = null)
+        DashboardSettingsService? dashboardSettings = null, FakeSchoolHolidays? schoolHolidays = null,
+        FakeLessons? lessons = null, FakeSubstitutionEntries? substitutions = null)
     {
-        var lessons = new FakeLessons();
+        lessons ??= new FakeLessons();
         lessons.Add(lesson);
         return new DashboardViewModel(
             new FakeGroups([group]), new FakeSubjects([]), lessons,
@@ -42,7 +51,9 @@ public sealed class DashboardViewModelTests
             tasks ?? new FakeWorkTasks(), new FakeSessions([]), new FakeEntries(),
             students ?? new FakeStudents([]), documentation ?? new FakeDocumentation(),
             slots ?? new FakeTimetableSlots(), periodSchedule ?? NewPeriodSchedule(),
-            new AttendanceBalanceService(), new SchoolYearService(), dashboardSettings ?? NewDashboardSettings());
+            new AttendanceBalanceService(), new SchoolYearService(), dashboardSettings ?? NewDashboardSettings(),
+            schoolHolidays ?? new FakeSchoolHolidays(), new PublicHolidayService(), NewCalendarSettings(),
+            substitutions ?? new FakeSubstitutionEntries());
     }
 
     [Fact]
@@ -227,4 +238,119 @@ public sealed class DashboardViewModelTests
         Assert.False(saved.Single(c => c.Key == "today").IsVisible);
         Assert.True(saved.FindIndex(c => c.Key == "tasks") > 1);
     }
+
+    // ── Ungeplante Stunden (Nutzer-Feedback) ──────────────────────────────────
+
+    [Fact]
+    public void UnplannedLessons_StundeplanSlotOhneLessonMitThema_ErscheintInDerListe()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "9c" };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 1 });
+        // "lesson" liegt bewusst weit in der Vergangenheit, damit sie nicht in den heute/morgen-
+        // Vorgriff fällt und den Test verfälscht.
+        var pastLesson = new Lesson { GroupId = group.Id, Date = today.AddYears(-1), LessonNumber = 1, Topic = "Alt" };
+
+        var vm = BuildVm(group, pastLesson, slots: slots);
+
+        var item = Assert.Single(vm.UnplannedLessons);
+        Assert.Equal(group.Id, item.GroupId);
+        Assert.Equal(1, item.PeriodNumber);
+        Assert.Equal("Heute", item.DateDisplay);
+    }
+
+    [Fact]
+    public void UnplannedLessons_LessonMitThemaVorhanden_ErscheintNicht()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "9c" };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 1 });
+        var lesson = new Lesson { GroupId = group.Id, Date = today, LessonNumber = 1, Topic = "Redoxreaktionen" };
+
+        var vm = BuildVm(group, lesson, slots: slots);
+
+        Assert.Empty(vm.UnplannedLessons);
+    }
+
+    [Fact]
+    public void UnplannedLessons_GruppeOhnePlanungsbedarf_WirdIgnoriert()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "Klassenrat", RequiresLessonPlanning = false };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 1 });
+        var pastLesson = new Lesson { GroupId = group.Id, Date = today.AddYears(-1), LessonNumber = 1, Topic = "Alt" };
+
+        var vm = BuildVm(group, pastLesson, slots: slots);
+
+        Assert.Empty(vm.UnplannedLessons);
+    }
+
+    [Fact]
+    public void UnplannedLessons_Feiertag_WirdUebersprungen()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "9c" };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 1 });
+        var pastLesson = new Lesson { GroupId = group.Id, Date = today.AddYears(-1), LessonNumber = 1, Topic = "Alt" };
+        var schoolHolidays = new FakeSchoolHolidays();
+        schoolHolidays.Add(new SchoolHoliday { Name = "Ferien", StartDate = today, EndDate = today.AddDays(1) });
+
+        var vm = BuildVm(group, pastLesson, slots: slots, schoolHolidays: schoolHolidays);
+
+        Assert.Empty(vm.UnplannedLessons);
+    }
+
+    [Fact]
+    public void UnplannedLessons_DoppelstundeMitThemaAmErstenSlot_ZweiterSlotWirdNichtGemeldet()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "9c" };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 3 });
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 4 });
+        var lesson = new Lesson { GroupId = group.Id, Date = today, LessonNumber = 3, Topic = "Redox" };
+
+        var vm = BuildVm(group, lesson, slots: slots);
+
+        Assert.Empty(vm.UnplannedLessons);
+    }
+
+    [Fact]
+    public void UnplannedLessons_DoppelstundeOhneThema_BeideSlotsWerdenGemeldet()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "9c" };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 3 });
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 4 });
+        var lesson = new Lesson { GroupId = group.Id, Date = today, LessonNumber = 3, Topic = "" };
+
+        var vm = BuildVm(group, lesson, slots: slots);
+
+        Assert.Equal(2, vm.UnplannedLessons.Count);
+        Assert.Contains(vm.UnplannedLessons, i => i.PeriodNumber == 3);
+        Assert.Contains(vm.UnplannedLessons, i => i.PeriodNumber == 4);
+    }
+
+    [Fact]
+    public void UnplannedLessons_StundenausfallEingetragen_WirdNichtGemeldet()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        var group = new LearningGroup { Name = "9c" };
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 5 });
+        slots.Add(new TimetableSlot { GroupId = group.Id, Weekday = today.DayOfWeek, PeriodNumber = 6 });
+        var pastLesson = new Lesson { GroupId = group.Id, Date = today.AddYears(-1), LessonNumber = 5, Topic = "Alt" };
+        var substitutions = new FakeSubstitutionEntries();
+        substitutions.Add(new SubstitutionEntry { Date = today, Kind = SubstitutionKind.Cancelled, PeriodNumber = 5 });
+        substitutions.Add(new SubstitutionEntry { Date = today, Kind = SubstitutionKind.Cancelled, PeriodNumber = 6 });
+
+        var vm = BuildVm(group, pastLesson, slots: slots, substitutions: substitutions);
+
+        Assert.Empty(vm.UnplannedLessons);
+    }
 }

LehrerApp.Desktop.Tests/Fakes.cs

@@ -1,5 +1,6 @@
 using LehrerApp.Core.Interfaces;
 using LehrerApp.Core.Models;
+using LehrerApp.Core.Services;
 using LehrerApp.Desktop.Services;
 using LehrerApp.Sync;
 
@@ -47,6 +48,14 @@ public static class TestSupport
         Directory.CreateDirectory(tempPath);
         return new EventQueue(Path.Combine(tempPath, "queue.db"));
     }
+
+    /// Analog zu <see cref="BuildAiSettingsService"/>, eigenes Temp-Verzeichnis je Aufruf.
+    public static PeriodScheduleService BuildPeriodScheduleService()
+    {
+        var tempPath = Path.Combine(Path.GetTempPath(), $"lehrerapp-periodschedule-tests-{Guid.NewGuid():N}");
+        Directory.CreateDirectory(tempPath);
+        return new PeriodScheduleService(tempPath);
+    }
 }
 
 public class FakeStudents(List<Student> all) : IStudentRepository

LehrerApp.Desktop.Tests/LessonDialogViewModelTests.cs

@@ -388,4 +388,53 @@ public sealed class LessonDialogViewModelTests
 
         Assert.False(vm.HasTimeBudgetInfo);
     }
+
+    // ── Datumsvorschlag für eine neue Stunde (Nutzer-Feedback: Feld stand sonst immer auf
+    // "heute", was die Doppelstunden-Erkennung stillschweigend auf eine Einzelperiode
+    // zurückfallen ließ, wenn heute zufällig nicht der Unterrichtstag ist) ────────────────────
+
+    [Fact]
+    public void NeueStunde_OhneStundenplanEintraege_BleibtBeimHeutigenDatum()
+    {
+        var vm = BuildVm(Guid.NewGuid(), Guid.NewGuid()); // FakeTimetableSlots leer
+
+        Assert.Equal(DateOnly.FromDateTime(DateTime.Today).ToString("dd.MM.yyyy"), vm.DateText);
+    }
+
+    [Fact]
+    public void NeueStunde_LetzteStundeInDerZukunft_SchlaegtNaechstenPassendenWochentagDanachVor()
+    {
+        var unitId = Guid.NewGuid();
+        var groupId = Guid.NewGuid();
+        var futureLessonDate = new DateOnly(2099, 1, 6); // Dienstag
+        var lessons = new FakeLessons();
+        lessons.Add(new Lesson { UnitId = unitId, GroupId = groupId, Date = futureLessonDate, LessonNumber = 3 });
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = DayOfWeek.Tuesday, PeriodNumber = 3 });
+
+        var vm = new LessonDialogViewModel(lessons, new FakeShorthandCodes([]), new FakeAlternativeLessonPaths([]),
+            slots, NewPeriodSchedule(), unitId, groupId, "10c", "Chemie", [], [], null);
+
+        // Nächster Dienstag nach dem 06.01.2099 (einem Dienstag) ist der 13.01.2099.
+        Assert.Equal("13.01.2099", vm.DateText);
+    }
+
+    [Fact]
+    public void NeueStunde_LetzteStundeInDerVergangenheit_SchlaegtNaechstenPassendenWochentagAbHeuteVor()
+    {
+        var unitId = Guid.NewGuid();
+        var groupId = Guid.NewGuid();
+        var lessons = new FakeLessons();
+        lessons.Add(new Lesson { UnitId = unitId, GroupId = groupId, Date = new DateOnly(2000, 1, 1), LessonNumber = 3 });
+        var weekday = DateTime.Today.DayOfWeek; // garantiert am selben oder folgenden Tag erreichbar
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = weekday, PeriodNumber = 3 });
+
+        var vm = new LessonDialogViewModel(lessons, new FakeShorthandCodes([]), new FakeAlternativeLessonPaths([]),
+            slots, NewPeriodSchedule(), unitId, groupId, "10c", "Chemie", [], [], null);
+
+        var suggested = DateOnly.ParseExact(vm.DateText, "dd.MM.yyyy");
+        Assert.True(suggested >= DateOnly.FromDateTime(DateTime.Today));
+        Assert.Equal(weekday, suggested.DayOfWeek);
+    }
 }

LehrerApp.Desktop.Tests/WorkloadViewModelTests.cs

@@ -1,3 +1,4 @@
+using LehrerApp.Core.Interfaces;
 using LehrerApp.Core.Models;
 using LehrerApp.Core.Services;
 using LehrerApp.Desktop.ViewModels.Workload;
@@ -288,14 +289,16 @@ public sealed class AddEditWorkTaskDialogViewModelTests
 
 public sealed class TimeTrackingViewModelTests
 {
+    private static TimeTrackingViewModel BuildVm(ITimeEntryRepository entries, IWorkTaskRepository tasks,
+        FakeTimetableSlots? slots = null) =>
+        new(entries, tasks, slots ?? new FakeTimetableSlots(), TestSupport.BuildPeriodScheduleService());
+
     [Fact]
     public void StartStopTimer_SpeichertZeiteintragMitMindestensEinerMinute()
     {
         var entries = new FakeTimeEntries();
-        var vm = new TimeTrackingViewModel(entries, new FakeWorkTasks())
-        {
-            SelectedTimerCategory = TaskCategoryDisplay.Label(TaskCategory.Correction),
-        };
+        var vm = BuildVm(entries, new FakeWorkTasks());
+        vm.SelectedTimerCategory = TaskCategoryDisplay.Label(TaskCategory.Correction);
 
         vm.StartTimerCommand.Execute(null);
         Assert.True(vm.IsTimerRunning);
@@ -314,7 +317,7 @@ public sealed class TimeTrackingViewModelTests
         var task = new WorkTask { Title = "T", Category = TaskCategory.Meeting };
         var tasks = new FakeWorkTasks();
         tasks.Add(task);
-        var vm = new TimeTrackingViewModel(new FakeTimeEntries(), tasks);
+        var vm = BuildVm(new FakeTimeEntries(), tasks);
 
         vm.SelectedTimerTask = task;
 
@@ -328,7 +331,7 @@ public sealed class TimeTrackingViewModelTests
         entries.Add(new TimeEntry { Category = "X", Date = DateOnly.FromDateTime(DateTime.Today), DurationMinutes = 30 });
         entries.Add(new TimeEntry { Category = "X", Date = DateOnly.FromDateTime(DateTime.Today).AddDays(-30), DurationMinutes = 45 });
 
-        var vm = new TimeTrackingViewModel(entries, new FakeWorkTasks());
+        var vm = BuildVm(entries, new FakeWorkTasks());
 
         Assert.Single(vm.WeekEntries);
         Assert.Equal(30, vm.WeekEntries[0].Model.DurationMinutes);
@@ -343,7 +346,7 @@ public sealed class TimeTrackingViewModelTests
         entries.Add(new TimeEntry { Category = "Korrektur", Date = today, DurationMinutes = 20 });
         entries.Add(new TimeEntry { Category = "Verwaltung", Date = today, DurationMinutes = 10 });
 
-        var vm = new TimeTrackingViewModel(entries, new FakeWorkTasks());
+        var vm = BuildVm(entries, new FakeWorkTasks());
 
         var korrektur = vm.CategorySummaries.Single(s => s.Category == "Korrektur");
         Assert.Equal("50 min", korrektur.MinutesDisplay);
@@ -356,7 +359,7 @@ public sealed class TimeTrackingViewModelTests
     {
         var entries = new FakeTimeEntries();
         entries.Add(new TimeEntry { Category = "X", Date = DateOnly.FromDateTime(DateTime.Today), DurationMinutes = 30 });
-        var vm = new TimeTrackingViewModel(entries, new FakeWorkTasks());
+        var vm = BuildVm(entries, new FakeWorkTasks());
 
         vm.DeleteEntryCommand.Execute(vm.WeekEntries[0]);
 
@@ -367,7 +370,7 @@ public sealed class TimeTrackingViewModelTests
     public async Task AddEntry_RuftOnAddEntryAufUndSpeichertErgebnis()
     {
         var entries = new FakeTimeEntries();
-        var vm = new TimeTrackingViewModel(entries, new FakeWorkTasks());
+        var vm = BuildVm(entries, new FakeWorkTasks());
         vm.OnAddEntry = () => Task.FromResult<TimeEntry?>(
             new TimeEntry { Category = "X", Date = DateOnly.FromDateTime(DateTime.Today), DurationMinutes = 15 });
 
@@ -375,6 +378,64 @@ public sealed class TimeTrackingViewModelTests
 
         Assert.Single(vm.WeekEntries);
     }
+
+    // ── Unterrichtszeit-Vorschlag (Nutzer-Feedback: Zeiterfassung soll bei der Unterrichtszeit
+    // nachfragen statt sie komplett automatisch zu erfassen) ────────────────────────────────────
+
+    [Fact]
+    public void HasTeachingTimeSuggestionToday_OhneStundenplanHeute_IstFalse()
+    {
+        var vm = BuildVm(new FakeTimeEntries(), new FakeWorkTasks()); // leere FakeTimetableSlots
+
+        Assert.False(vm.HasTeachingTimeSuggestionToday);
+    }
+
+    [Fact]
+    public async Task SuggestTeachingTime_SchlaegtBeginnMitPufferVorErsterUndNachLetzterPeriodeVor()
+    {
+        var today = DateTime.Today.DayOfWeek;
+        var slots = new FakeTimetableSlots();
+        slots.Add(new TimetableSlot { Weekday = today, PeriodNumber = 1 });
+        slots.Add(new TimetableSlot { Weekday = today, PeriodNumber = 2 });
+        var periodSchedule = TestSupport.BuildPeriodScheduleService();
+        periodSchedule.SetPeriods([
+            new PeriodTimeEntry { PeriodNumber = 1, Start = new TimeOnly(7, 50), End = new TimeOnly(8, 35) },
+            new PeriodTimeEntry { PeriodNumber = 2, Start = new TimeOnly(8, 35), End = new TimeOnly(9, 20) },
+        ]);
+        var entries = new FakeTimeEntries();
+        var vm = new TimeTrackingViewModel(entries, new FakeWorkTasks(), slots, periodSchedule);
+
+        Assert.True(vm.HasTeachingTimeSuggestionToday);
+
+        (TimeOnly Start, TimeOnly End)? suggested = null;
+        vm.OnSuggestTeachingTime = (start, end) =>
+        {
+            suggested = (start, end);
+            return Task.FromResult<TimeEntry?>(new TimeEntry
+            {
+                Category = "Unterricht", Date = DateOnly.FromDateTime(DateTime.Today),
+                StartTime = start, EndTime = end, DurationMinutes = (int)(end - start).TotalMinutes,
+            });
+        };
+
+        await vm.SuggestTeachingTimeCommand.ExecuteAsync(null);
+
+        Assert.Equal(new TimeOnly(7, 35), suggested!.Value.Start); // 7:50 - 15 Min Puffer
+        Assert.Equal(new TimeOnly(9, 30), suggested.Value.End);    // 9:20 + 10 Min Puffer
+        Assert.Single(entries.GetByDate(DateOnly.FromDateTime(DateTime.Today)));
+    }
+
+    [Fact]
+    public async Task SuggestTeachingTime_OhneStundenplanHeute_TutNichts()
+    {
+        var vm = BuildVm(new FakeTimeEntries(), new FakeWorkTasks());
+        var called = false;
+        vm.OnSuggestTeachingTime = (_, _) => { called = true; return Task.FromResult<TimeEntry?>(null); };
+
+        await vm.SuggestTeachingTimeCommand.ExecuteAsync(null);
+
+        Assert.False(called);
+    }
 }
 
 public sealed class AddTimeEntryDialogViewModelTests