Back navigation and shell improvements.

Wino.Core.Domain/Interfaces/IStatePersistenceService.cs

@@ -28,11 +28,6 @@ public interface IStatePersistanceService : INotifyPropertyChanged
     /// </summary>
     bool IsReaderNarrowed { get; set; }
 
-    /// <summary>
-    /// Should display back button on the shell title bar.
-    /// </summary>
-    bool IsBackButtonVisible { get; }
-
     /// <summary>
     /// Current application mode (Mail or Calendar).
     /// Not persisted to configuration, only kept in memory.
@@ -44,11 +39,6 @@ public interface IStatePersistanceService : INotifyPropertyChanged
     /// </summary>
     bool IsEventDetailsVisible { get; set; }
 
-    /// <summary>
-    /// Whether the current application mode has an active backstack that can be navigated.
-    /// </summary>
-    bool HasCurrentModeBackStack { get; set; }
-
     /// <summary>
     /// Setting: Opened pane length for the navigation view.
     /// </summary>

Wino.Core.Domain/Interfaces/IWinoNavigationService.cs

@@ -13,5 +13,6 @@ public interface INavigationService
 
     Type GetPageType(WinoPage winoPage);
     bool ChangeApplicationMode(WinoApplicationMode mode);
+    bool CanGoBack();
     void GoBack(NavigationTransitionEffect slideEffect = NavigationTransitionEffect.FromRight);
 }

Wino.Core.Domain/Models/Calendar/CalendarRangeTextFormatter.cs

@@ -20,12 +20,20 @@ public sealed class CalendarRangeTextFormatter : ICalendarRangeTextFormatter
             return FormatDate(range.StartDate, culture);
         }
 
+        if (range.SpansSingleMonth)
+        {
+            return $"{FormatDate(range.StartDate, culture)} - {FormatDay(range.EndDate, culture)}";
+        }
+
         return $"{FormatDate(range.StartDate, culture)} - {FormatDate(range.EndDate, culture)}";
     }
 
     private static string FormatDate(DateOnly date, CultureInfo culture)
         => date.ToString(culture.DateTimeFormat.MonthDayPattern, culture);
 
+    private static string FormatDay(DateOnly date, CultureInfo culture)
+        => date.Day.ToString(culture);
+
     private static string FormatMonth(DateOnly date, CultureInfo culture)
         => date.ToString(culture.DateTimeFormat.YearMonthPattern, culture);
 }

Wino.Core.Tests/CalendarRangeTextFormatterTests.cs

@@ -32,7 +32,7 @@ public class CalendarRangeTextFormatterTests
             startDate: new DateOnly(2026, 3, 3),
             endDate: new DateOnly(2026, 3, 10));
 
-        Formatter.Format(range, DateContextProvider).Should().Be("March 3 - March 10");
+        Formatter.Format(range, DateContextProvider).Should().Be("March 3 - 10");
     }
 
     [Fact]

Wino.Mail.WinUI/Services/NavigationService.cs

@@ -219,6 +219,9 @@ public class NavigationService : NavigationServiceBase, INavigationService
     public bool ChangeApplicationMode(WinoApplicationMode mode)
         => ExecuteOnNavigationThread(() => ChangeApplicationModeInternal(mode));
 
+    public bool CanGoBack()
+        => ExecuteOnNavigationThread(CanGoBackInternal);
+
     private bool ChangeApplicationModeInternal(WinoApplicationMode mode, object? activationParameter = null)
     {
         var coreFrame = GetCoreFrameInternal(NavigationReferenceFrame.ShellFrame);
@@ -333,7 +336,6 @@ public class NavigationService : NavigationServiceBase, INavigationService
                     if (innerShellFrame.CanGoBack && lastBackStackEntry?.SourcePageType == pageType)
                     {
                         innerShellFrame.GoBack();
-                        UpdateCurrentModeBackStackState(innerShellFrame);
                         WeakReferenceMessenger.Default.Send(loadCalendarMessage);
                         return true;
                     }
@@ -495,7 +497,7 @@ public class NavigationService : NavigationServiceBase, INavigationService
 
         if (navigationResult)
         {
-            UpdateCurrentModeBackStackState(frame);
+            return true;
         }
 
         return navigationResult;
@@ -522,15 +524,13 @@ public class NavigationService : NavigationServiceBase, INavigationService
         var currentApplicationMode = _statePersistanceService.ApplicationMode;
 
         if (currentApplicationMode == WinoApplicationMode.Settings &&
-            _statePersistanceService.HasCurrentModeBackStack)
+            innerShellFrame?.Content is SettingsPage settingsPage)
+        {
+            if (settingsPage.CanNavigateBack)
             {
                 WeakReferenceMessenger.Default.Send(new BackBreadcrumNavigationRequested(slideEffect));
-            return;
             }
 
-        if (currentApplicationMode == WinoApplicationMode.Settings &&
-            innerShellFrame?.Content is SettingsPage)
-        {
             return;
         }
 
@@ -544,7 +544,6 @@ public class NavigationService : NavigationServiceBase, INavigationService
             if (innerShellFrame?.CanGoBack == true)
             {
                 innerShellFrame.GoBack();
-                UpdateCurrentModeBackStackState(innerShellFrame);
             }
             else if (innerShellFrame != null && innerShellFrame.Content?.GetType() != typeof(CalendarPage))
             {
@@ -560,16 +559,11 @@ public class NavigationService : NavigationServiceBase, INavigationService
             {
                 // Mail mode: Clear selections and dispose rendering frame
                 _statePersistanceService.IsReadingMail = false;
-                _statePersistanceService.HasCurrentModeBackStack = false;
 
                 WeakReferenceMessenger.Default.Send(new ClearMailSelectionsRequested());
                 WeakReferenceMessenger.Default.Send(new DisposeRenderingFrameRequested());
             }
         }
-        else
-        {
-            UpdateCurrentModeBackStackState(innerShellFrame);
-        }
     }
 
     private void ResetCurrentModeBackStackState()
@@ -581,17 +575,6 @@ public class NavigationService : NavigationServiceBase, INavigationService
             innerShellFrame.BackStack.Clear();
             innerShellFrame.ForwardStack.Clear();
         }
-
-        _statePersistanceService.HasCurrentModeBackStack = false;
-    }
-
-    private void UpdateCurrentModeBackStackState(Frame? innerShellFrame)
-    {
-        if (_statePersistanceService.ApplicationMode == WinoApplicationMode.Settings)
-            return;
-
-        _statePersistanceService.HasCurrentModeBackStack = _statePersistanceService.ApplicationMode == WinoApplicationMode.Calendar &&
-                                                           innerShellFrame?.CanGoBack == true;
     }
 
     private void PruneInnerShellBackStackForMode(Frame frame, WinoApplicationMode mode)
@@ -636,7 +619,33 @@ public class NavigationService : NavigationServiceBase, INavigationService
 
         frame.BackStack.Clear();
         frame.ForwardStack.Clear();
-        UpdateCurrentModeBackStackState(frame);
+    }
+
+    private bool CanGoBackInternal()
+    {
+        var innerShellFrame = GetCoreFrameInternal(NavigationReferenceFrame.InnerShellFrame);
+
+        return _statePersistanceService.ApplicationMode switch
+        {
+            WinoApplicationMode.Mail => _statePersistanceService.IsReadingMail && _statePersistanceService.IsReaderNarrowed,
+            WinoApplicationMode.Settings => innerShellFrame?.Content is SettingsPage settingsPage && settingsPage.CanNavigateBack,
+            WinoApplicationMode.Calendar or WinoApplicationMode.Contacts => HasModeScopedBackStack(innerShellFrame, _statePersistanceService.ApplicationMode),
+            _ => false
+        };
+    }
+
+    private bool HasModeScopedBackStack(Frame? innerShellFrame, WinoApplicationMode mode)
+    {
+        if (innerShellFrame == null || innerShellFrame.BackStack.Count == 0)
+            return false;
+
+        for (int i = innerShellFrame.BackStack.Count - 1; i >= 0; i--)
+        {
+            if (IsPageTypeAllowedInMode(mode, innerShellFrame.BackStack[i].SourcePageType))
+                return true;
+        }
+
+        return false;
     }
 
     // Standalone EML viewer.

Wino.Mail.WinUI/Services/StatePersistenceService.cs

@@ -32,23 +32,12 @@ public class StatePersistenceService : ObservableObject, IStatePersistanceServic
 
     private void ServicePropertyChanged(object? sender, PropertyChangedEventArgs e) => StatePropertyChanged?.Invoke(this, e?.PropertyName ?? string.Empty);
 
-    public bool IsBackButtonVisible =>
-        ApplicationMode == WinoApplicationMode.Mail
-            ? (IsReadingMail && IsReaderNarrowed) || HasCurrentModeBackStack
-            : HasCurrentModeBackStack;
-
     private WinoApplicationMode applicationMode = WinoApplicationMode.Mail;
 
     public WinoApplicationMode ApplicationMode
     {
         get => applicationMode;
-        set
+        set => SetProperty(ref applicationMode, value);
-        {
-            if (SetProperty(ref applicationMode, value))
-            {
-                OnPropertyChanged(nameof(IsBackButtonVisible));
-            }
-        }
     }
 
     private bool isEventDetailsVisible;
@@ -60,40 +49,18 @@ public class StatePersistenceService : ObservableObject, IStatePersistanceServic
         {
             if (SetProperty(ref isEventDetailsVisible, value))
             {
-                OnPropertyChanged(nameof(IsBackButtonVisible));
-
                 IsReaderNarrowed = value;
                 IsReadingMail = value;
             }
         }
     }
 
-    private bool hasCurrentModeBackStack;
-
-    public bool HasCurrentModeBackStack
-    {
-        get => hasCurrentModeBackStack;
-        set
-        {
-            if (SetProperty(ref hasCurrentModeBackStack, value))
-            {
-                OnPropertyChanged(nameof(IsBackButtonVisible));
-            }
-        }
-    }
-
     private bool isReadingMail;
 
     public bool IsReadingMail
     {
         get => isReadingMail;
-        set
+        set => SetProperty(ref isReadingMail, value);
-        {
-            if (SetProperty(ref isReadingMail, value))
-            {
-                OnPropertyChanged(nameof(IsBackButtonVisible));
-            }
-        }
     }
 
     private bool shouldShiftMailRenderingDesign;
@@ -109,13 +76,7 @@ public class StatePersistenceService : ObservableObject, IStatePersistanceServic
     public bool IsReaderNarrowed
     {
         get => isReaderNarrowed;
-        set
+        set => SetProperty(ref isReaderNarrowed, value);
-        {
-            if (SetProperty(ref isReaderNarrowed, value))
-            {
-                OnPropertyChanged(nameof(IsBackButtonVisible));
-            }
-        }
     }
 
     private string coreWindowTitle = string.Empty;

Wino.Mail.WinUI/ShellWindow.xaml

@@ -31,10 +31,13 @@
             VerticalContentAlignment="Stretch"
             BackRequested="BackButtonClicked"
             Background="Transparent"
-            IsBackButtonVisible="{x:Bind StatePersistanceService.IsBackButtonVisible, Mode=OneWay}"
             IsPaneToggleButtonVisible="True"
             PaneToggleRequested="PaneButtonClicked"
             Subtitle="{x:Bind StatePersistanceService.CoreWindowTitle, Mode=OneWay}">
+            <TitleBar.Resources>
+                <HorizontalAlignment x:Key="TitleBarContentHorizontalAlignment">Stretch</HorizontalAlignment>
+                <VerticalAlignment x:Key="TitleBarContentVerticalAlignment">Stretch</VerticalAlignment>
+            </TitleBar.Resources>
             <TitleBar.RightHeader>
                 <StackPanel Orientation="Horizontal" Spacing="8">
                     <Button

Wino.Mail.WinUI/ShellWindow.xaml.cs

@@ -46,12 +46,14 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
     private ICalendarShellClient? _activeCalendarClient;
     private readonly CalendarTitleBarContent _calendarTitleBarContent = new();
     private long _calendarTypeSelectorChangedToken;
+    private bool _isBackButtonVisibilityReady;
 
     public ShellWindow()
     {
         RegisterRecipients();
 
         InitializeComponent();
+        StatePersistanceService.StatePropertyChanged += StatePersistenceServiceChanged;
 
         MinWidth = 420;
         MinHeight = 420;
@@ -138,7 +140,9 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
             _ = StartCalendarReminderServerAsync();
         }
 
+        _isBackButtonVisibilityReady = true;
         ApplyTitleBarContent();
+        RefreshBackButtonVisibility();
     }
 
     private async Task StartCalendarReminderServerAsync()
@@ -166,6 +170,7 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
     public void Receive(TitleBarShellContentUpdated message)
     {
         ApplyTitleBarContent();
+        RefreshBackButtonVisibility();
     }
 
     public void Receive(ApplicationThemeChanged message)
@@ -279,6 +284,7 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
         {
             AttachCalendarClient(null);
             ShellTitleBar.Content = MainShellFrame.Content is BasePage basePage ? basePage.ShellContent : null;
+            RefreshBackButtonVisibility();
             return;
         }
 
@@ -288,10 +294,43 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
         {
             RefreshCalendarSelector();
             ShellTitleBar.Content = _calendarTitleBarContent;
+            RefreshBackButtonVisibility();
             return;
         }
 
         ShellTitleBar.Content = shellPage.GetShellFrame().Content is BasePage page ? page.ShellContent : null;
+        RefreshBackButtonVisibility();
+    }
+
+    private void StatePersistenceServiceChanged(object? sender, string propertyName)
+    {
+        if (!DispatcherQueue.HasThreadAccess)
+        {
+            var enqueued = DispatcherQueue.TryEnqueue(() => StatePersistenceServiceChanged(sender, propertyName));
+            if (!enqueued)
+                throw new InvalidOperationException("Could not marshal shell state changes onto the UI thread.");
+
+            return;
+        }
+
+        if (propertyName == nameof(IStatePersistanceService.ApplicationMode) ||
+            propertyName == nameof(IStatePersistanceService.IsReadingMail) ||
+            propertyName == nameof(IStatePersistanceService.IsReaderNarrowed) ||
+            propertyName == nameof(IStatePersistanceService.IsEventDetailsVisible))
+        {
+            RefreshBackButtonVisibility();
+        }
+    }
+
+    private void RefreshBackButtonVisibility()
+    {
+        if (!_isBackButtonVisibilityReady)
+        {
+            ShellTitleBar.IsBackButtonVisible = false;
+            return;
+        }
+
+        ShellTitleBar.IsBackButtonVisible = NavigationService.CanGoBack();
     }
 
     private void AttachCalendarClient(ICalendarShellClient? calendarClient)
@@ -390,6 +429,7 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
     {
         AppWindow.Closing -= OnAppWindowClosing;
         AttachCalendarClient(null);
+        StatePersistanceService.StatePropertyChanged -= StatePersistenceServiceChanged;
         _calendarTitleBarContent.UnregisterSelectedTypeChanged(_calendarTypeSelectorChangedToken);
         _calendarTitleBarContent.PreviousDateRequested -= CalendarTitleBarContentPreviousDateRequested;
         _calendarTitleBarContent.NextDateRequested -= CalendarTitleBarContentNextDateRequested;

Wino.Mail.WinUI/Views/SettingsPage.xaml.cs

@@ -77,9 +77,6 @@ public sealed partial class SettingsPage : SettingsPageAbstract,
         // Unregister frame navigation event
         SettingsFrame.Navigated -= SettingsFrameNavigated;
 
-        // Reset navigation state when leaving SettingsPage
-        ViewModel.StatePersistenceService.HasCurrentModeBackStack = false;
-
         base.OnNavigatingFrom(e);
     }
 
@@ -225,9 +222,11 @@ public sealed partial class SettingsPage : SettingsPageAbstract,
 
     private void UpdateBackNavigationState()
     {
-        ViewModel.StatePersistenceService.HasCurrentModeBackStack = PageHistory.Count > 1 && SettingsFrame.CanGoBack;
+        WeakReferenceMessenger.Default.Send(new TitleBarShellContentUpdated());
     }
 
+    public bool CanNavigateBack => PageHistory.Count > 1 && SettingsFrame.CanGoBack;
+
     private async Task RefreshCurrentPageStateAsync()
     {
         var activePage = PageHistory.LastOrDefault()?.Request.PageType ?? WinoPage.SettingOptionsPage;

Wino.Mail.WinUI/Views/WinoAppShell.xaml.cs

@@ -157,7 +157,6 @@ public sealed partial class WinoAppShell : Views.Abstract.WinoAppShellAbstract,
 
     private void ResetShellModeNavigationState()
     {
-        ViewModel.StatePersistenceService.HasCurrentModeBackStack = false;
         InnerShellFrame.BackStack.Clear();
         InnerShellFrame.ForwardStack.Clear();
     }