Refactor settings management in PLib video library manager. Replace dialog-based settings with a single-panel overlay for improved user experience. Update MainWindow and SettingsView to support new settings panel, and adjust ViewModels accordingly. Enhance README.md to reflect these changes.

README.md

@@ -9,8 +9,9 @@
 - Метаданные (длительность, разрешение, кодек) через ffprobe.
 - Постеры кадром из видео через ffmpeg, с кэшем на диске.
 - Виртуализированная сетка карточек, ленивая загрузка превью, поиск и сортировка.
-- Окно настроек: папки библиотеки (с удалением), параметры превью и сканирования, тема,
+- Настройки — выдвижной панелью в том же окне: папки библиотеки (с удалением), параметры
-  очистка кэша превью. Всё пишется в `settings.json` и подхватывается без перезапуска.
+  превью и сканирования, тема, очистка кэша. Всё пишется в `settings.json` и подхватывается
+  без перезапуска.
 - Светлая, тёмная и системная темы; выбор запоминается.
 - Клик или Enter по карточке — открыть в системном плеере, правая кнопка — контекстное меню.
 
@@ -62,7 +63,10 @@ dotnet test
   декодированием в нужную ширину. Память зависит от размера окна, а не от размера библиотеки.
 - **Scope на операцию.** `DbContext` живёт ровно одну операцию — ViewModel берёт
   `IServiceScopeFactory` и создаёт scope на каждый вызов.
-- **Настройки — рабочая копия.** Диалог правит снимок `AppSettings` и записывает его целиком
+- **Одно окно.** Настройки — панель поверх сетки, а не второе окно: библиотека остаётся
+  видна, в alt-tab ничего не добавляется, и приложение остаётся переносимым на
+  `ISingleViewApplicationLifetime`, где `ShowDialog` попросту не существует.
+- **Настройки — рабочая копия.** Панель правит снимок `AppSettings` и записывает его целиком
   только по «Сохранить», так что отмена не оставляет следов. Пересканирование запускается
   только если изменилось то, что влияет на состав библиотеки, — смена темы или ширины кадра
   его не вызывает.

src/PLib.Desktop/AppHost.cs

@@ -48,7 +48,6 @@ internal static class AppHost
         builder.Services.AddSingleton<ThumbnailCache>();
         builder.Services.AddSingleton<IThumbnailLoader>(sp => sp.GetRequiredService<ThumbnailCache>());
         builder.Services.AddSingleton<IAppSettingsStore, JsonAppSettingsStore>();
-        builder.Services.AddSingleton<IDialogService, DialogService>();
         builder.Services.AddSingleton<IFolderPicker, StorageProviderFolderPicker>();
         builder.Services.AddSingleton<ISystemShell, SystemShell>();
         builder.Services.AddSingleton<IThemeService, ThemeService>();

src/PLib.Desktop/Services/DialogService.cs

@@ -1,42 +0,0 @@
-using System.Reactive.Linq;
-using Avalonia.Controls.ApplicationLifetimes;
-using Microsoft.Extensions.DependencyInjection;
-using PLib.Desktop.ViewModels;
-using PLib.Desktop.Views;
-
-namespace PLib.Desktop.Services;
-
-/// <summary>Opens the application's dialogs, so view models never touch window types.</summary>
-public interface IDialogService
-{
-    Task<SettingsDialogOutcome> ShowSettingsAsync();
-}
-
-/// <inheritdoc cref="IDialogService"/>
-public sealed class DialogService(IServiceScopeFactory scopeFactory) : IDialogService
-{
-    public async Task<SettingsDialogOutcome> ShowSettingsAsync()
-    {
-        if (Avalonia.Application.Current?.ApplicationLifetime
-            is not IClassicDesktopStyleApplicationLifetime { MainWindow: { } owner })
-        {
-            return SettingsDialogOutcome.Cancelled;
-        }
-
-        // A scope per dialog: the container would otherwise keep every settings view model
-        // it ever built alive until shutdown, and disposing the scope disposes the model.
-        await using var scope = scopeFactory.CreateAsyncScope();
-        var viewModel = scope.ServiceProvider.GetRequiredService<SettingsViewModel>();
-
-        var window = new SettingsWindow { DataContext = viewModel };
-
-        // The view model decides when it is done; the window only carries the answer out.
-        using var subscription = viewModel.Closed.Subscribe(outcome => window.Close(outcome));
-
-        // Show a real number in the cache section rather than an empty label.
-        await viewModel.RefreshCacheSizeCommand.Execute().FirstAsync();
-
-        // Closing through the title bar yields null, which counts as cancelling.
-        return await window.ShowDialog<SettingsDialogOutcome?>(owner) ?? SettingsDialogOutcome.Cancelled;
-    }
-}

src/PLib.Desktop/Themes/LibraryStyles.axaml

@@ -104,6 +104,58 @@
     <Setter Property="FontSize" Value="12.5" />
   </Style>
 
+  <!-- ======================== Settings overlay ======================== -->
+
+  <!--
+    The overlay stays in the tree and hides behind opacity rather than IsVisible: a collapsed
+    element has nothing to animate from, and the slide-in is the whole point. Nothing inside
+    is focusable while it is closed, because the panel's content is null until it opens.
+  -->
+  <Style Selector="Panel.settingsOverlay">
+    <Setter Property="Opacity" Value="0" />
+    <Setter Property="IsHitTestVisible" Value="False" />
+    <Setter Property="Transitions">
+      <Transitions>
+        <DoubleTransition Property="Opacity" Duration="0:0:0.16" Easing="CubicEaseOut" />
+      </Transitions>
+    </Setter>
+  </Style>
+
+  <Style Selector="Panel.settingsOverlay.open">
+    <Setter Property="Opacity" Value="1" />
+    <Setter Property="IsHitTestVisible" Value="True" />
+  </Style>
+
+  <!-- Click-anywhere-to-dismiss backdrop. A Button gets the click handling for free. -->
+  <Style Selector="Button.scrim">
+    <Setter Property="Background" Value="{DynamicResource OverlayBrush}" />
+    <Setter Property="Focusable" Value="False" />
+    <Setter Property="Cursor" Value="Arrow" />
+    <Setter Property="Template">
+      <ControlTemplate>
+        <Border Background="{TemplateBinding Background}" />
+      </ControlTemplate>
+    </Setter>
+  </Style>
+
+  <Style Selector="Border.drawer">
+    <Setter Property="HorizontalAlignment" Value="Right" />
+    <Setter Property="Width" Value="470" />
+    <Setter Property="Background" Value="{DynamicResource PageBackgroundBrush}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SurfaceBorderBrush}" />
+    <Setter Property="BorderThickness" Value="1,0,0,0" />
+    <Setter Property="RenderTransform" Value="translateX(30px)" />
+    <Setter Property="Transitions">
+      <Transitions>
+        <TransformOperationsTransition Property="RenderTransform" Duration="0:0:0.2" Easing="CubicEaseOut" />
+      </Transitions>
+    </Setter>
+  </Style>
+
+  <Style Selector="Panel.settingsOverlay.open Border.drawer">
+    <Setter Property="RenderTransform" Value="none" />
+  </Style>
+
   <!-- ============================ Badge ============================ -->
 
   <Style Selector="Border.badge">

src/PLib.Desktop/ViewModels/MainWindowViewModel.cs

@@ -35,7 +35,6 @@ public sealed partial class MainWindowViewModel : ViewModelBase
     private readonly IOptionsMonitor<LibraryOptions> _options;
     private readonly IAppSettingsStore _settingsStore;
     private readonly IOptionsMonitor<AppearanceOptions> _appearance;
-    private readonly IDialogService _dialogs;
     private readonly IThemeService _theme;
     private readonly IFolderPicker _folderPicker;
     private readonly ISystemShell _shell;
@@ -60,13 +59,13 @@ public sealed partial class MainWindowViewModel : ViewModelBase
     private readonly ReadOnlyObservableCollection<VideoCardViewModel> _videos;
     private readonly ObservableAsPropertyHelper<bool> _isScanning;
     private readonly ObservableAsPropertyHelper<bool> _isEmpty;
+    private readonly ObservableAsPropertyHelper<bool> _isSettingsOpen;
 
     public MainWindowViewModel(
         IServiceScopeFactory scopeFactory,
         IOptionsMonitor<LibraryOptions> options,
         IOptionsMonitor<AppearanceOptions> appearance,
         IAppSettingsStore settingsStore,
-        IDialogService dialogs,
         IFolderPicker folderPicker,
         ISystemShell shell,
         IThemeService theme,
@@ -76,7 +75,6 @@ public sealed partial class MainWindowViewModel : ViewModelBase
         _options = options;
         _appearance = appearance;
         _settingsStore = settingsStore;
-        _dialogs = dialogs;
         _theme = theme;
         _folderPicker = folderPicker;
         _shell = shell;
@@ -87,7 +85,19 @@ public sealed partial class MainWindowViewModel : ViewModelBase
         InitializeCommand = ReactiveCommand.CreateFromTask(InitializeAsync);
         AddFolderCommand = ReactiveCommand.CreateFromTask(AddFolderAsync);
         ToggleThemeCommand = ReactiveCommand.CreateFromTask(ToggleThemeAsync);
-        OpenSettingsCommand = ReactiveCommand.CreateFromTask(OpenSettingsAsync);
+
+        _isSettingsOpen = this
+            .WhenAnyValue(x => x.SettingsPanel)
+            .Select(panel => panel is not null)
+            .ToProperty(this, x => x.IsSettingsOpen);
+
+        OpenSettingsCommand = ReactiveCommand.CreateFromTask(
+            OpenSettingsAsync,
+            this.WhenAnyValue(x => x.IsSettingsOpen).Select(open => !open));
+
+        CloseSettingsCommand = ReactiveCommand.Create(
+            () => { SettingsPanel?.CancelCommand.Execute().Subscribe(); },
+            this.WhenAnyValue(x => x.IsSettingsOpen));
 
         // Cancellation the ReactiveUI way: the scan runs as an observable, and cancelling
         // simply unsubscribes it, which cancels the token Observable.StartAsync handed out.
@@ -128,6 +138,17 @@ public sealed partial class MainWindowViewModel : ViewModelBase
 
     public ReactiveCommand<RxVoid, RxVoid> OpenSettingsCommand { get; }
 
+    public ReactiveCommand<RxVoid, RxVoid> CloseSettingsCommand { get; }
+
+    /// <summary>
+    /// The settings panel while it is on screen, or <c>null</c>. Its presence is what the
+    /// overlay binds to — settings live in this window rather than a second one.
+    /// </summary>
+    [Reactive]
+    public partial SettingsViewModel? SettingsPanel { get; set; }
+
+    public bool IsSettingsOpen => _isSettingsOpen.Value;
+
     [Reactive]
     public partial string SearchText { get; set; }
 
@@ -204,7 +225,8 @@ public sealed partial class MainWindowViewModel : ViewModelBase
                 CancelScanCommand.ThrownExceptions,
                 AddFolderCommand.ThrownExceptions,
                 ToggleThemeCommand.ThrownExceptions,
-                OpenSettingsCommand.ThrownExceptions)
+                OpenSettingsCommand.ThrownExceptions,
+                CloseSettingsCommand.ThrownExceptions)
             .Subscribe(ex =>
             {
                 _logger.LogError(ex, "A command failed");
@@ -313,14 +335,35 @@ public sealed partial class MainWindowViewModel : ViewModelBase
 
     private async Task OpenSettingsAsync()
     {
-        var outcome = await _dialogs.ShowSettingsAsync();
+        // A scope per opening: the panel edits a working copy, so a cancelled edit must not
+        // survive into the next time it is opened, and disposing the scope disposes it.
+        await using var scope = _scopeFactory.CreateAsyncScope();
+        var panel = scope.ServiceProvider.GetRequiredService<SettingsViewModel>();
+
+        // Fill in the cache size before the panel appears, so the number never pops in late.
+        await panel.RefreshCacheSizeCommand.Execute().FirstAsync();
+
+        SettingsPanel = panel;
+
+        SettingsDialogOutcome outcome;
+
+        try
+        {
+            outcome = await panel.Closed.FirstAsync();
+        }
+        finally
+        {
+            // Close first: a rescan started below would otherwise run behind a panel the
+            // user has already dismissed.
+            SettingsPanel = null;
+        }
 
         if (outcome is not { Saved: true, Settings: { } saved })
         {
             return;
         }
 
-        // The dialog wrote the file; wait for the configuration to catch up before anything
+        // The panel wrote the file; wait for the configuration to catch up before anything
         // reads it back, otherwise the rescan below would use the previous folder list.
         await WaitForConfigurationAsync(
             () => _options.CurrentValue.Folders.SequenceEqual(saved.Folders, LibraryPathComparer.Instance));

src/PLib.Desktop/ViewModels/SettingsViewModel.cs

@@ -57,9 +57,9 @@ public sealed partial class SettingsViewModel : ViewModelBase
 
         Folders = [.. _original.Folders.Select(CreateEntry)];
         ThumbnailWidth = _original.ThumbnailWidth;
-        ThumbnailPositionPercent = Math.Round(_original.ThumbnailPositionRatio * 100);
+        ThumbnailPositionPercent = ToPercent(_original.ThumbnailPositionRatio);
         MaxIndexingConcurrency = _original.MaxIndexingConcurrency;
-        MinimumFileSizeMegabytes = Math.Round(_original.MinimumFileSizeInBytes / BytesPerMegabyte, 2);
+        MinimumFileSizeMegabytes = ToMegabytes(_original.MinimumFileSizeInBytes);
         SelectedTheme = ThemeOptions.First(option => option.Mode == _original.Theme);
 
         AddFolderCommand = ReactiveCommand.CreateFromTask(AddFolderAsync);
@@ -127,12 +127,28 @@ public sealed partial class SettingsViewModel : ViewModelBase
     {
         Folders = [.. Folders.Select(entry => entry.Path)],
         ThumbnailWidth = ThumbnailWidth,
-        ThumbnailPositionRatio = Math.Round(ThumbnailPositionPercent / 100, 4),
+
+        // Both of these are shown in a friendlier unit than they are stored in, and that
+        // conversion is lossy: 65 536 bytes displays as 0,06 MB and converts back to 62 915.
+        // An untouched field therefore keeps the original value verbatim — otherwise merely
+        // opening the panel and pressing Save would rewrite settings and force a rescan.
+        ThumbnailPositionRatio = ThumbnailPositionPercent == ToPercent(_original.ThumbnailPositionRatio)
+            ? _original.ThumbnailPositionRatio
+            : Math.Round(ThumbnailPositionPercent / 100, 4),
+
         MaxIndexingConcurrency = MaxIndexingConcurrency,
-        MinimumFileSizeInBytes = (long)Math.Round(MinimumFileSizeMegabytes * BytesPerMegabyte),
+
+        MinimumFileSizeInBytes = MinimumFileSizeMegabytes == ToMegabytes(_original.MinimumFileSizeInBytes)
+            ? _original.MinimumFileSizeInBytes
+            : (long)Math.Round(MinimumFileSizeMegabytes * BytesPerMegabyte),
+
         Theme = SelectedTheme.Mode,
     };
 
+    private static double ToPercent(double ratio) => Math.Round(ratio * 100);
+
+    private static double ToMegabytes(long bytes) => Math.Round(bytes / BytesPerMegabyte, 2);
+
     private async Task AddFolderAsync()
     {
         var folder = await _folderPicker.PickFolderAsync("Выберите папку с видео");

src/PLib.Desktop/Views/MainWindow.axaml

@@ -2,6 +2,7 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:controls="clr-namespace:PLib.Desktop.Controls"
         xmlns:icons="clr-namespace:Material.Icons.Avalonia;assembly=Material.Icons.Avalonia"
+        xmlns:views="clr-namespace:PLib.Desktop.Views"
         xmlns:vm="clr-namespace:PLib.Desktop.ViewModels"
         x:Class="PLib.Desktop.Views.MainWindow"
         x:DataType="vm:MainWindowViewModel"
@@ -15,6 +16,10 @@
 
   <Window.Resources>
 
+    <DataTemplate x:Key="SettingsTemplate" DataType="vm:SettingsViewModel">
+      <views:SettingsView />
+    </DataTemplate>
+
     <!-- ======================= Video card ======================= -->
     <DataTemplate x:Key="VideoCardTemplate" DataType="vm:VideoCardViewModel">
       <Button Classes="card" Command="{Binding PlayCommand}" ToolTip.Tip="{Binding FullPath}">
@@ -234,5 +239,17 @@
       </Grid>
     </Border>
 
+    <!-- ======================= Settings panel ======================= -->
+    <Panel Grid.Row="0"
+           Grid.RowSpan="3"
+           Classes="settingsOverlay"
+           Classes.open="{Binding IsSettingsOpen}">
+      <Button Classes="scrim" Command="{Binding CloseSettingsCommand}" />
+      <Border Classes="drawer">
+        <ContentControl Content="{Binding SettingsPanel}"
+                        ContentTemplate="{StaticResource SettingsTemplate}" />
+      </Border>
+    </Panel>
+
   </Grid>
 </Window>

src/PLib.Desktop/Views/MainWindow.axaml.cs

@@ -1,9 +1,35 @@
-using ReactiveUI.Avalonia;
+using Avalonia.Input;
+using Avalonia.Interactivity;
 using PLib.Desktop.ViewModels;
+using ReactiveUI.Avalonia;
 
 namespace PLib.Desktop.Views;
 
 public sealed partial class MainWindow : ReactiveWindow<MainWindowViewModel>
 {
-    public MainWindow() => InitializeComponent();
+    public MainWindow()
+    {
+        InitializeComponent();
+
+        // Handled here rather than as a KeyBinding: a KeyBinding only fires if the event
+        // bubbles all the way up untouched, and whichever control inside the settings panel
+        // happens to hold focus may well swallow Escape first. Both strategies are
+        // registered because a focused control can mark the event handled on the way down.
+        AddHandler(
+            KeyDownEvent,
+            OnPreviewKeyDown,
+            RoutingStrategies.Tunnel | RoutingStrategies.Bubble,
+            handledEventsToo: true);
+    }
+
+    private void OnPreviewKeyDown(object? sender, KeyEventArgs e)
+    {
+        if (e.Key is not Key.Escape || DataContext is not MainWindowViewModel { IsSettingsOpen: true } viewModel)
+        {
+            return;
+        }
+
+        viewModel.CloseSettingsCommand.Execute().Subscribe();
+        e.Handled = true;
+    }
 }

src/PLib.Desktop/Views/SettingsView.axaml

@@ -1,18 +1,11 @@
-<Window xmlns="https://github.com/avaloniaui"
+<UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:icons="clr-namespace:Material.Icons.Avalonia;assembly=Material.Icons.Avalonia"
              xmlns:vm="clr-namespace:PLib.Desktop.ViewModels"
-        x:Class="PLib.Desktop.Views.SettingsWindow"
+             x:Class="PLib.Desktop.Views.SettingsView"
-        x:DataType="vm:SettingsViewModel"
+             x:DataType="vm:SettingsViewModel">
-        Title="Настройки"
-        Width="620"
-        Height="700"
-        MinWidth="520"
-        MinHeight="520"
-        Background="{DynamicResource PageBackgroundBrush}"
-        WindowStartupLocation="CenterOwner">
 
-  <Window.Styles>
+  <UserControl.Styles>
     <!-- One settings block: a titled surface holding a few related controls. -->
     <Style Selector="Border.section">
       <Setter Property="Background" Value="{DynamicResource SurfaceBrush}" />
@@ -33,7 +26,7 @@
       <Setter Property="FontSize" Value="11.5" />
       <Setter Property="TextWrapping" Value="Wrap" />
     </Style>
-  </Window.Styles>
+  </UserControl.Styles>
 
   <Grid RowDefinitions="Auto,*,Auto">
 
@@ -43,8 +36,9 @@
             BorderBrush="{DynamicResource SurfaceBorderBrush}"
             BorderThickness="0,0,0,1"
             Padding="20,14">
-      <StackPanel Orientation="Horizontal" Spacing="10">
+      <Grid ColumnDefinitions="Auto,*,Auto">
-        <Border Width="32"
+        <Border Grid.Column="0"
+                Width="32"
                 Height="32"
                 CornerRadius="9"
                 Background="{DynamicResource AccentSoftBrush}">
@@ -53,8 +47,18 @@
                               Height="18"
                               Foreground="{DynamicResource AccentBrush}" />
         </Border>
-        <TextBlock Classes="sectionTitle" Text="Настройки" VerticalAlignment="Center" />
+        <TextBlock Grid.Column="1"
-      </StackPanel>
+                   Classes="sectionTitle"
+                   Margin="10,0,0,0"
+                   Text="Настройки"
+                   VerticalAlignment="Center" />
+        <Button Grid.Column="2"
+                Command="{Binding CancelCommand}"
+                Padding="7"
+                ToolTip.Tip="Закрыть без сохранения">
+          <icons:MaterialIcon Kind="Close" Width="15" Height="15" />
+        </Button>
+      </Grid>
     </Border>
 
     <!-- ======================= Body ======================= -->
@@ -241,4 +245,4 @@
     </Border>
 
   </Grid>
-</Window>
+</UserControl>

src/PLib.Desktop/Views/SettingsView.axaml.cs

@@ -0,0 +1,8 @@
+using Avalonia.Controls;
+
+namespace PLib.Desktop.Views;
+
+public sealed partial class SettingsView : UserControl
+{
+    public SettingsView() => InitializeComponent();
+}

src/PLib.Desktop/Views/SettingsWindow.axaml.cs

@@ -1,9 +0,0 @@
-using PLib.Desktop.ViewModels;
-using ReactiveUI.Avalonia;
-
-namespace PLib.Desktop.Views;
-
-public sealed partial class SettingsWindow : ReactiveWindow<SettingsViewModel>
-{
-    public SettingsWindow() => InitializeComponent();
-}

tests/PLib.Tests/Settings/SettingsViewModelTests.cs

@@ -0,0 +1,107 @@
+using System.Reactive.Linq;
+using System.Reactive.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using NSubstitute;
+using PLib.Application.Library;
+using PLib.Desktop.Services;
+using PLib.Desktop.Settings;
+using PLib.Desktop.ViewModels;
+using Shouldly;
+
+namespace PLib.Tests.Settings;
+
+public sealed class SettingsViewModelTests
+{
+    private readonly IAppSettingsStore _store = Substitute.For<IAppSettingsStore>();
+
+    [Fact]
+    public async Task Opening_and_saving_without_touching_anything_changes_nothing()
+    {
+        // Both of these are displayed in a lossier unit than they are stored in: 65 536 bytes
+        // shows as 0,06 MB. Converting the untouched field back used to yield 62 915, which
+        // silently rewrote the setting and forced a full rescan on every visit to the panel.
+        var options = new LibraryOptions
+        {
+            Folders = [@"C:\videos"],
+            MinimumFileSizeInBytes = 65_536,
+            ThumbnailPositionRatio = 0.15,
+        };
+
+        var (viewModel, outcome) = await SaveAsync(options);
+
+        outcome.RescanRequired.ShouldBeFalse();
+        Written.MinimumFileSizeInBytes.ShouldBe(65_536);
+        Written.ThumbnailPositionRatio.ShouldBe(0.15);
+        viewModel.HasFolders.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task Editing_the_minimum_size_does_write_the_new_value()
+    {
+        var (_, outcome) = await SaveAsync(
+            new LibraryOptions { Folders = [@"C:\videos"], MinimumFileSizeInBytes = 65_536 },
+            viewModel => viewModel.MinimumFileSizeMegabytes = 4);
+
+        Written.MinimumFileSizeInBytes.ShouldBe(4 * 1024 * 1024);
+        outcome.RescanRequired.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task Removing_a_folder_is_carried_into_the_saved_settings()
+    {
+        var (_, outcome) = await SaveAsync(
+            new LibraryOptions { Folders = [@"C:\a", @"C:\b"] },
+            viewModel => viewModel.Folders[0].RemoveCommand.Execute().Subscribe());
+
+        Written.Folders.ShouldBe([@"C:\b"]);
+        outcome.RescanRequired.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task Cancelling_writes_nothing()
+    {
+        var viewModel = Create(new LibraryOptions { Folders = [@"C:\videos"] });
+        var closed = viewModel.Closed.FirstAsync().ToTask();
+
+        viewModel.MinimumFileSizeMegabytes = 999;
+        await viewModel.CancelCommand.Execute().FirstAsync().ToTask(TestContext.Current.CancellationToken);
+
+        (await closed).Saved.ShouldBeFalse();
+        _store.ReceivedCalls().ShouldBeEmpty();
+    }
+
+    private AppSettings Written =>
+        (AppSettings)_store.ReceivedCalls().Single(call => call.GetMethodInfo().Name == nameof(IAppSettingsStore.SaveAsync))
+            .GetArguments()[0]!;
+
+    private async Task<(SettingsViewModel ViewModel, SettingsDialogOutcome Outcome)> SaveAsync(
+        LibraryOptions options,
+        Action<SettingsViewModel>? edit = null)
+    {
+        var viewModel = Create(options);
+        var closed = viewModel.Closed.FirstAsync().ToTask();
+
+        edit?.Invoke(viewModel);
+        await viewModel.SaveCommand.Execute().FirstAsync().ToTask(TestContext.Current.CancellationToken);
+
+        return (viewModel, await closed);
+    }
+
+    private SettingsViewModel Create(LibraryOptions options) => new(
+        Substitute.For<IServiceScopeFactory>(),
+        Monitor(options),
+        Monitor(new AppearanceOptions()),
+        _store,
+        Substitute.For<IFolderPicker>(),
+        Substitute.For<IThemeService>(),
+        NullLogger<SettingsViewModel>.Instance);
+
+    private static IOptionsMonitor<T> Monitor<T>(T value)
+    {
+        var monitor = Substitute.For<IOptionsMonitor<T>>();
+        monitor.CurrentValue.Returns(value);
+        return monitor;
+    }
+}