refactor: split Background out of MainViewModel — Commit 4/12 (tag refactor-commit-4)

ViewModels/MainViewModel.Background.cs

@@ -0,0 +1,568 @@
+using System.Collections.ObjectModel;
+using System.IO;
+using System.Windows;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using ytLive.Helpers;
+using ytLive.Models;
+using ytLive.Services;
+
+namespace ytLive.ViewModels;
+
+public partial class MainViewModel
+{
+    // Screen background: a permanent live capture (desktop/game) that every scene
+    // shows at the bottom layer. One shared capture session per key — the
+    // ScreenCaptureManager refcounts by key, mirroring CameraManager.
+    private readonly IFullScreenDetector _fullScreenDetector;
+    private readonly ScreenCaptureManager _screenCaptureManager;
+    private readonly ScreenCaptureSourceFactory _screenCaptureFactory;
+
+    private ImageSource? _activeBackgroundImage;
+    private ImageSource? _backgroundImage;
+    private bool _backgroundSizeMismatch;
+    private string _backgroundSizeMismatchText = "";
+    private HashSet<string> _liveCaptureKeys = new();
+
+    public ObservableCollection<DisplayInfo> Displays { get; } = new();
+
+    public ImageSource? ActiveBackgroundImage
+    {
+        get => _activeBackgroundImage;
+        private set => SetProperty(ref _activeBackgroundImage, value);
+    }
+
+    /// <summary>The active scene's live-capture background frame (rendered below the
+    /// static background). Set from the shared capture bitmap as it arrives.</summary>
+    public ImageSource? BackgroundImage
+    {
+        get => _backgroundImage;
+        private set
+        {
+            if (SetProperty(ref _backgroundImage, value))
+            {
+                OnPropertyChanged(nameof(ShowPreviewPlaceholder));
+                OnPropertyChanged(nameof(BackgroundVisible));
+            }
+        }
+    }
+
+    public bool BackgroundVisible => StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground)?.IsVisible == true;
+
+    public bool BackgroundSizeMismatch
+    {
+        get => _backgroundSizeMismatch;
+        private set => SetProperty(ref _backgroundSizeMismatch, value);
+    }
+
+    public string BackgroundSizeMismatchText
+    {
+        get => _backgroundSizeMismatchText;
+        private set => SetProperty(ref _backgroundSizeMismatchText, value);
+    }
+
+    public ICommand ChangeCaptureCommand { get; }
+    public ICommand RefreshCaptureCommand { get; }
+    public ICommand SetBackgroundDisplayCommand { get; }
+    public ICommand ToggleShowDesktopCommand { get; }
+    public ICommand BrowseBackgroundCommand { get; }
+
+    private void UpdateActiveBackground()
+    {
+        // Static-art rows only. Capture-flavored rows (Live) must NEVER feed
+        // ActiveBackgroundImage — it renders above BackgroundImage, so it would
+        // permanently cover the desktop/game capture. Live's canvas shows
+        // DisplaySource instead (capture, falling back to live-background.jpg).
+        var background = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
+        ActiveBackgroundImage = background != null && !string.IsNullOrWhiteSpace(background.AssetId)
+            ? ImageCache.Get(background.AssetId)
+            : null;
+        OnPropertyChanged(nameof(ShowPreviewPlaceholder));
+    }
+
+    private void UpdateBackgroundImage()
+    {
+        var scene = StagedScene;
+        var background = scene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+        BackgroundImage = background?.DisplaySource;
+
+        if (background != null && !background.UseDefaultBackground
+            && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)
+            && System.IO.File.Exists(background.CustomBackgroundPath))
+        {
+            try
+            {
+                var bmi = new System.Windows.Media.Imaging.BitmapImage();
+                bmi.BeginInit();
+                bmi.UriSource = new System.Uri(background.CustomBackgroundPath);
+                bmi.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
+                bmi.EndInit();
+                bmi.Freeze();
+
+                double expectedRatio = 1920.0 / 1080.0;
+                double imageRatio = (double)bmi.PixelWidth / bmi.PixelHeight;
+                double ratioDiff = Math.Abs(imageRatio - expectedRatio) / expectedRatio;
+
+                if (ratioDiff > 0.05)
+                {
+                    BackgroundSizeMismatch = true;
+                    BackgroundSizeMismatchText =
+                        $"Image is {bmi.PixelWidth}\u00d7{bmi.PixelHeight} \u2014 stream expects 1920\u00d71080 (16:9)";
+                }
+                else
+                {
+                    BackgroundSizeMismatch = false;
+                    BackgroundSizeMismatchText = "";
+                }
+            }
+            catch
+            {
+                BackgroundSizeMismatch = false;
+                BackgroundSizeMismatchText = "";
+            }
+        }
+        else
+        {
+            BackgroundSizeMismatch = false;
+            BackgroundSizeMismatchText = "";
+        }
+    }
+
+    private void RefreshSnapshotsAsync()
+    {
+        foreach (var scene in Scenes)
+        {
+            // Minis never render live captures. While the Live screen is staged
+            // (being previewed) its mini shows the green placeholder; unstaged,
+            // it shows the stored default art. Real-time surface = center only.
+            var stagedLive = ReferenceEquals(scene, StagedScene)
+                && SceneCatalog.Is(scene.Name, SceneCatalog.Live);
+            var img = stagedLive ? null : LoadBackgroundImage(scene);
+            if (img != null)
+                scene.Snapshot = img;
+            else if (scene.Snapshot == null || stagedLive)
+                scene.Snapshot = CreatePlaceholderSnapshot(scene.Name);
+        }
+    }
+
+    internal static System.Windows.Media.Imaging.BitmapSource? LoadBackgroundImage(Scene scene)
+    {
+        var bg = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+        if (bg != null && !bg.UseDefaultBackground
+            && !string.IsNullOrWhiteSpace(bg.CustomBackgroundPath)
+            && System.IO.File.Exists(bg.CustomBackgroundPath))
+        {
+            try
+            {
+                var bitmap = new System.Windows.Media.Imaging.BitmapImage();
+                bitmap.BeginInit();
+                bitmap.UriSource = new Uri(bg.CustomBackgroundPath);
+                bitmap.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
+                bitmap.EndInit();
+                bitmap.Freeze();
+                return bitmap;
+            }
+            catch { /* fall through to AssetId */ }
+        }
+        if (bg != null && !string.IsNullOrWhiteSpace(bg.AssetId))
+            return ImageCache.Get(bg.AssetId);
+        return null;
+    }
+
+    private static BitmapSource CreatePlaceholderSnapshot(string sceneName)
+    {
+        var colors = new Dictionary<string, System.Windows.Media.Brush>(StringComparer.OrdinalIgnoreCase)
+        {
+            ["Starting"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(233, 69, 96)),
+            ["Live"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(34, 197, 94)),
+            ["BRB"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(234, 179, 8)),
+            ["Chat"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(59, 130, 246)),
+            ["Ending"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(168, 85, 247)),
+        };
+        var brush = colors.TryGetValue(sceneName, out var c) ? c
+            : new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(60, 60, 80));
+        var dv = new System.Windows.Media.DrawingVisual();
+        using (var ctx = dv.RenderOpen())
+        {
+            ctx.DrawRectangle(brush, null, new System.Windows.Rect(0, 0, 320, 180));
+            var ft = new System.Windows.Media.FormattedText(
+                sceneName,
+                System.Globalization.CultureInfo.InvariantCulture,
+                System.Windows.FlowDirection.LeftToRight,
+                new System.Windows.Media.Typeface("Segoe UI"),
+                18,
+                System.Windows.Media.Brushes.White,
+                96);
+            ctx.DrawText(ft, new System.Windows.Point(160 - ft.Width / 2, 90 - ft.Height / 2));
+        }
+        var rtb = new System.Windows.Media.Imaging.RenderTargetBitmap(
+            320, 180, 96, 96, System.Windows.Media.PixelFormats.Pbgra32);
+        rtb.Render(dv);
+        rtb.Freeze();
+        return rtb;
+    }
+
+    // ─── Screen background capture (live desktop/game) ───
+
+    private const string MonitorKeyPrefix = "monitor:";
+
+    /// <summary>Every background-enabled scene has exactly one background, kept at index 0 (bottom layer).
+    /// Returns null for a scene with <see cref="Scene.HasBackground"/> = false.</summary>
+    internal static Source? EnsureBackground(Scene scene)
+    {
+        if (!scene.HasBackground) return null;
+        var background = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+        if (background != null) return background;
+
+        background = CreateBackground(scene.Name);
+        scene.Elements.Insert(0, background);
+        return background;
+    }
+
+    /// <summary>The one Background row for a scene. Live gets the capture flavor
+    /// (Show Desktop / monitor switch / fullscreen-game detect) falling back to
+    /// live-background.jpg; every other screen is a static default-art layer.
+    /// Both are named "Background" — the user never sees capture jargon here.</summary>
+    internal static Source CreateBackground(string sceneName)
+    {
+        var isLive = SceneCatalog.Is(sceneName, SceneCatalog.Live);
+        return new Source
+        {
+            Name = "Background",
+            Type = isLive ? SourceType.DisplayCapture : SourceType.Background,
+            IsBackground = true,
+            IsEnabled = true,
+            X = 0,
+            Y = 0,
+            Width = MasterFrameWidth,
+            Height = MasterFrameHeight,
+        };
+    }
+
+    /// <summary>Heals any loaded layout to the locked Background model: exactly
+    /// one Background per canonical scene, correct flavor for the scene (static
+    /// art everywhere, DisplayCapture on Live only), at index 0, named
+    /// "Background". Duplicates and stale rows are dropped; missing ones seeded;
+    /// non-canonical scenes get HasBackground=false and lose any backgrounds.</summary>
+    internal static void NormalizeBackgrounds(IEnumerable<Scene> scenes)
+    {
+        foreach (var scene in scenes)
+        {
+            if (!SceneCatalog.HasBackground(scene.Name))
+            {
+                scene.HasBackground = false;
+                foreach (var stale in scene.Elements.OfType<Source>().Where(s => s.IsBackground).ToList())
+                    scene.Elements.Remove(stale);
+                continue;
+            }
+
+            scene.HasBackground = true;
+            var isLive = SceneCatalog.Is(scene.Name, SceneCatalog.Live);
+            var wantedType = isLive ? SourceType.DisplayCapture : SourceType.Background;
+
+            var candidates = scene.Elements.OfType<Source>().Where(s => s.IsBackground).ToList();
+            var keep = candidates.FirstOrDefault(b => b.Type == wantedType) ?? candidates.FirstOrDefault();
+
+            foreach (var extra in candidates.Where(b => !ReferenceEquals(b, keep)))
+                scene.Elements.Remove(extra);
+
+            if (keep == null)
+            {
+                keep = CreateBackground(scene.Name);
+                scene.Elements.Insert(0, keep);
+            }
+
+            // Source.Type's setter derives IsBackground from the enum, so a
+            // flavor correction must re-assert the flag afterwards.
+            if (keep.Type != wantedType)
+            {
+                keep.Type = wantedType;
+                keep.IsBackground = true;
+            }
+
+            keep.Name = "Background";
+            keep.IsEnabled = true;
+
+            var index = scene.Elements.IndexOf(keep);
+            if (index > 0)
+                scene.Elements.Move(index, 0);
+        }
+    }
+
+    // Only the Live screen's background is a real-time surface. Every other
+    // lookup below (auto-capture, focus hooks, refresh) must ignore the static
+    // default-art rows so they can never start a desktop capture session.
+    private IEnumerable<Source> AllBackgrounds()
+        => Scenes.Where(s => SceneCatalog.Is(s.Name, SceneCatalog.Live))
+            .SelectMany(s => s.Elements.OfType<Source>().Where(x => x.IsBackground));
+
+    // Full-screen game on its monitor, else null (static bg fallback — no
+    // infinity mirror). Called at launch (from ReacquireScreenCaptures, before
+    // the window steals focus) and on focus regain (RefreshBackgroundAutoCapture).
+    // When a background has ShowDesktop=true, returns the primary monitor instead
+    // of null so the desktop is always visible.
+    private string? ResolveAutoCaptureKey()
+    {
+        var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
+        if (gameMonitor != null)
+            return $"{MonitorKeyPrefix}{gameMonitor}";
+
+        if (AllBackgrounds().Any(b => b.ShowDesktop))
+            return $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
+        return null;
+    }
+
+    // After a layout load / file open: make sure every background-enabled scene
+    // has a background, give any background without a persisted key the auto-detected
+    // one, then acquire one capture per unique background key. ScreenCaptureManager
+    // refcounts by key, so every scene pointing at the same monitor shares one
+    // session. Captures no longer referenced by any scene are released.
+    private void ReacquireScreenCaptures()
+    {
+        HealBackgrounds();
+
+        var auto = ResolveAutoCaptureKey();
+        if (auto == null)
+        {
+            foreach (var background in AllBackgrounds())
+                background.CaptureKey = null;
+        }
+        else
+        {
+            foreach (var background in AllBackgrounds())
+                if (string.IsNullOrWhiteSpace(background.CaptureKey))
+                    background.CaptureKey = auto;
+        }
+
+        var keys = AllBackgrounds()
+            .Select(b => b.CaptureKey!)
+            .Where(k => !string.IsNullOrWhiteSpace(k))
+            .ToHashSet();
+
+        // A layout reload replaces the scenes; stop captures that are no longer
+        // referenced (mirrors ReacquireWebcam's device swap).
+        foreach (var stale in _liveCaptureKeys.Except(keys))
+            _ = _screenCaptureManager.ReleaseAllAsync(stale);
+        _liveCaptureKeys = keys;
+
+        foreach (var key in keys)
+            _ = _screenCaptureManager.AcquireAsync(key);
+
+        _fullScreenDetector.StartWatching();
+    }
+
+    // ScreenCaptureManager creates the shared WriteableBitmap on the UI thread;
+    // every background pointing at that key picks it up.
+    private void OnScreenPreviewBitmapChanged(string key, WriteableBitmap bitmap)
+    {
+        var activeBackground = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+        if (activeBackground?.CaptureKey == key)
+            BackgroundImage = bitmap;
+
+        foreach (var background in AllBackgrounds().Where(b => b.CaptureKey == key))
+            background.VideoImageSource = bitmap;
+    }
+
+    // EVENT_SYSTEM_FOREGROUND fires whenever the foreground window changes.
+    // When a full-screen game appears on a different monitor than the current
+    // background, auto-redesignate. When ShowDesktop is enabled and no fullscreen
+    // game is detected, fall back to the primary monitor (desktop view).
+    private void OnFullscreenMonitorChanged(int? monitor)
+    {
+        if (monitor != null)
+        {
+            var newKey = $"{MonitorKeyPrefix}{monitor}";
+            var current = AllBackgrounds().FirstOrDefault();
+            if (current?.CaptureKey == newKey) return;
+            _ = RedesignateBackgroundAsync(newKey);
+        }
+        else if (AllBackgrounds().Any(b => b.ShowDesktop))
+        {
+            var desktopKey = $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
+            var current = AllBackgrounds().FirstOrDefault();
+            if (current?.CaptureKey == desktopKey) return;
+            _ = RedesignateBackgroundAsync(desktopKey);
+        }
+    }
+
+    // Manual refresh: the "Refresh Capture" context menu item. Reads the
+    // current foreground directly (no caching needed — the hook handles
+    // automatic detection).
+    public void RefreshBackgroundAutoCapture()
+    {
+        var detected = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
+        if (detected == null) return;
+        _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{detected}");
+    }
+
+    /// <summary>Whether the active background is in Show Desktop mode.
+    /// Bindable IsChecked property for the context menu toggle.</summary>
+    public bool BackgroundShowDesktop
+    {
+        get => StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground)?.ShowDesktop ?? false;
+        set
+        {
+            var background = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+            if (background == null || background.ShowDesktop == value) return;
+            background.ShowDesktop = value;
+            OnPropertyChanged(nameof(BackgroundShowDesktop));
+            ScheduleSave();
+            if (value)
+            {
+                _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}");
+            }
+            else
+            {
+                var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
+                if (gameMonitor != null)
+                    _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{gameMonitor}");
+                else
+                    _ = ClearBackgroundCaptureAsync();
+            }
+        }
+    }
+
+    private void ToggleBackgroundShowDesktop() => BackgroundShowDesktop = !BackgroundShowDesktop;
+
+    private void BrowseBackground()
+    {
+        var scene = StagedScene;
+        if (scene == null) return;
+        var bg = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+        if (bg == null) return;
+
+        var dlg = new Microsoft.Win32.OpenFileDialog
+        {
+            Title = "Select background image",
+            Filter = "Image files (*.jpg;*.jpeg;*.png;*.bmp)|*.jpg;*.jpeg;*.png;*.bmp|All files (*.*)|*.*",
+        };
+        if (dlg.ShowDialog() != true) return;
+
+        bg.CustomBackgroundPath = dlg.FileName;
+        bg.UseDefaultBackground = false;
+        try
+        {
+            using var fs = new System.IO.FileStream(dlg.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
+            var bytes = new byte[fs.Length];
+            fs.Read(bytes, 0, bytes.Length);
+            var assetId = AddAsset(bytes);
+            if (assetId != null)
+                bg.AssetId = assetId;
+        }
+        catch { /* non-critical */ }
+
+        UpdateActiveBackground();
+        RefreshSnapshotsAsync();
+        ScheduleSave();
+    }
+
+    /// <summary>Release the background capture so the static placeholder image shows.</summary>
+    private async Task ClearBackgroundCaptureAsync()
+    {
+        var oldKeys = AllBackgrounds()
+            .Select(b => b.CaptureKey!)
+            .Where(k => !string.IsNullOrWhiteSpace(k))
+            .ToHashSet();
+
+        foreach (var background in AllBackgrounds())
+        {
+            background.CaptureKey = null;
+            background.VideoImageSource = null;
+        }
+
+        foreach (var key in oldKeys)
+            await _screenCaptureManager.ReleaseAllAsync(key);
+
+        _liveCaptureKeys.Clear();
+        UpdateBackgroundImage();
+        ScheduleSave();
+    }
+
+    private async Task RedesignateBackgroundAsync(string newKey)
+    {
+        var oldKeys = AllBackgrounds()
+            .Select(b => b.CaptureKey!)
+            .Where(k => !string.IsNullOrWhiteSpace(k))
+            .ToHashSet();
+
+        foreach (var background in AllBackgrounds())
+            background.CaptureKey = newKey;
+
+        foreach (var oldKey in oldKeys.Where(k => k != newKey))
+            await _screenCaptureManager.ReleaseAllAsync(oldKey);
+        if (!oldKeys.Contains(newKey))
+            await _screenCaptureManager.AcquireAsync(newKey);
+        _liveCaptureKeys = new HashSet<string> { newKey };
+        UpdateBackgroundImage();
+        ScheduleSave();
+    }
+
+    // "Change Capture…": the OS GraphicsCapturePicker designates the target.
+    // Picks are transient (see ScreenCaptureSourceFactory) — a reload falls
+    // back to auto-detection.
+    public async Task ChangeBackgroundCaptureAsync()
+    {
+        var key = await _screenCaptureFactory.PickAsync();
+        if (key == null) return;
+        await RedesignateBackgroundAsync(key);
+    }
+
+    // In-app display picker: point every background at a specific monitor.
+    private void SetBackgroundCapture(DisplayInfo? display)
+    {
+        if (display == null) return;
+        _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{display.Index}");
+    }
+
+    // ─── Background model (TASK 25): exactly ONE Background per screen, index 0,
+    // never removable or re-addable. Static default art on Starting/BRB/Chat/Ending;
+    // on Live it's the capture-flavored row (Show Desktop / monitor switch /
+    // fullscreen-game detect) falling back to live-background.jpg. ───
+
+    private static string? DefaultBackgroundAsset(string sceneName) => sceneName switch
+    {
+        SceneCatalog.Starting => "starting-background.jpg",
+        SceneCatalog.Brb => "brb-background.jpg",
+        SceneCatalog.Chat => "chat-background.jpg",
+        SceneCatalog.Ending => "ending-background.jpg",
+        SceneCatalog.Live => "live-background.jpg",
+        _ => null,
+    };
+
+    /// <summary>Heals every scene to the locked Background model after a layout
+    /// load: keeps the correct flavor per scene at index 0 named "Background",
+    /// drops duplicates/stale rows, re-seeds missing ones.</summary>
+    private void HealBackgrounds()
+    {
+        NormalizeBackgrounds(Scenes);
+        foreach (var scene in Scenes)
+        {
+            var background = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+            if (background != null)
+                StampDefaultBackgroundAsset(background, scene.Name);
+        }
+        OnPropertyChanged(nameof(ShowSourcesEmptyHint));
+    }
+
+    /// <summary>Points a background row at its scene's shipped default art when it
+    /// carries none. A custom image (Browse…) always wins and is never overwritten.</summary>
+    private void StampDefaultBackgroundAsset(Source background, string sceneName)
+    {
+        if (!string.IsNullOrWhiteSpace(background.AssetId)) return;
+        if (!background.UseDefaultBackground && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)) return;
+        var asset = DefaultBackgroundAsset(sceneName);
+        if (asset == null) return;
+
+        try
+        {
+            var uri = new Uri($"pack://application:,,,/Assets/{asset}", UriKind.Absolute);
+            using var stream = Application.GetResourceStream(uri)?.Stream;
+            if (stream == null) return;
+            using var ms = new MemoryStream();
+            stream.CopyTo(ms);
+            background.AssetId = AddAsset(ms.ToArray());
+        }
+        catch { /* non-critical — the app works without default art */ }
+    }
+}

ViewModels/MainViewModel.cs

@@ -32,7 +32,6 @@ public partial class MainViewModel : ViewModelBase
     private readonly DispatcherTimer _healthPollTimer;
 
     private SceneElement? _selectedElement;
-    private ImageSource? _activeBackgroundImage;
     private double _audioLevel;
     private bool _volumeAdjusting;
     private bool _volumeFlash;
@@ -133,12 +132,6 @@ public partial class MainViewModel : ViewModelBase
     private readonly FramePump _framePump;
     private readonly TransitionService _transition = new();
 
-    // Screen background: a permanent live capture (desktop/game) that every scene
-    // shows at the bottom layer. One shared capture session per key — the
-    // ScreenCaptureManager refcounts by key, mirroring CameraManager.
-    private readonly IFullScreenDetector _fullScreenDetector;
-    private readonly ScreenCaptureManager _screenCaptureManager;
-    private readonly ScreenCaptureSourceFactory _screenCaptureFactory;
     private readonly ChatBoxRenderer _chatBoxRenderer;
     private WebView2Manager? _webView2Manager;
 
@@ -152,11 +145,6 @@ public partial class MainViewModel : ViewModelBase
         new ChatMessage { AuthorName = "LlamaCasty", Message = "thanks for watching! llamacasty.com", Timestamp = DateTime.Now.AddMinutes(-1), IsMember = true },
         new ChatMessage { AuthorName = "LlamaDog", Message = "Subscribe so they can buy the subscription at llamacasty.com!", Timestamp = DateTime.Now, IsMember = true },
     };
-    private ImageSource? _backgroundImage;
-    private bool _backgroundSizeMismatch;
-    private string _backgroundSizeMismatchText = "";
-    private HashSet<string> _liveCaptureKeys = new();
-
     // Chat fade timer: clears chat overlay after N seconds of inactivity.
     private System.Windows.Threading.DispatcherTimer? _chatFadeTimer;
 
@@ -186,42 +174,6 @@ public partial class MainViewModel : ViewModelBase
     public string LicensesText { get; private set; } = string.Empty;
 
     public ObservableCollection<ChatMessage> ChatMessages { get; } = new();
-    public ObservableCollection<DisplayInfo> Displays { get; } = new();
-
-    public ImageSource? ActiveBackgroundImage
-    {
-        get => _activeBackgroundImage;
-        private set => SetProperty(ref _activeBackgroundImage, value);
-    }
-
-    /// <summary>The active scene's live-capture background frame (rendered below the
-    /// static background). Set from the shared capture bitmap as it arrives.</summary>
-    public ImageSource? BackgroundImage
-    {
-        get => _backgroundImage;
-        private set
-        {
-            if (SetProperty(ref _backgroundImage, value))
-            {
-                OnPropertyChanged(nameof(ShowPreviewPlaceholder));
-                OnPropertyChanged(nameof(BackgroundVisible));
-            }
-        }
-    }
-
-    public bool BackgroundVisible => StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground)?.IsVisible == true;
-
-    public bool BackgroundSizeMismatch
-    {
-        get => _backgroundSizeMismatch;
-        private set => SetProperty(ref _backgroundSizeMismatch, value);
-    }
-
-    public string BackgroundSizeMismatchText
-    {
-        get => _backgroundSizeMismatchText;
-        private set => SetProperty(ref _backgroundSizeMismatchText, value);
-    }
 
     public SceneElement? SelectedElement
     {
@@ -869,141 +821,6 @@ public partial class MainViewModel : ViewModelBase
         private set => SetProperty(ref _brandFlashActive, value);
     }
 
-    private void UpdateActiveBackground()
-    {
-        // Static-art rows only. Capture-flavored rows (Live) must NEVER feed
-        // ActiveBackgroundImage — it renders above BackgroundImage, so it would
-        // permanently cover the desktop/game capture. Live's canvas shows
-        // DisplaySource instead (capture, falling back to live-background.jpg).
-        var background = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
-        ActiveBackgroundImage = background != null && !string.IsNullOrWhiteSpace(background.AssetId)
-            ? ImageCache.Get(background.AssetId)
-            : null;
-        OnPropertyChanged(nameof(ShowPreviewPlaceholder));
-    }
-
-    private void UpdateBackgroundImage()
-    {
-        var scene = StagedScene;
-        var background = scene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-        BackgroundImage = background?.DisplaySource;
-
-        if (background != null && !background.UseDefaultBackground
-            && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)
-            && System.IO.File.Exists(background.CustomBackgroundPath))
-        {
-            try
-            {
-                var bmi = new System.Windows.Media.Imaging.BitmapImage();
-                bmi.BeginInit();
-                bmi.UriSource = new System.Uri(background.CustomBackgroundPath);
-                bmi.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
-                bmi.EndInit();
-                bmi.Freeze();
-
-                double expectedRatio = 1920.0 / 1080.0;
-                double imageRatio = (double)bmi.PixelWidth / bmi.PixelHeight;
-                double ratioDiff = Math.Abs(imageRatio - expectedRatio) / expectedRatio;
-
-                if (ratioDiff > 0.05)
-                {
-                    BackgroundSizeMismatch = true;
-                    BackgroundSizeMismatchText =
-                        $"Image is {bmi.PixelWidth}\u00d7{bmi.PixelHeight} \u2014 stream expects 1920\u00d71080 (16:9)";
-                }
-                else
-                {
-                    BackgroundSizeMismatch = false;
-                    BackgroundSizeMismatchText = "";
-                }
-            }
-            catch
-            {
-                BackgroundSizeMismatch = false;
-                BackgroundSizeMismatchText = "";
-            }
-        }
-        else
-        {
-            BackgroundSizeMismatch = false;
-            BackgroundSizeMismatchText = "";
-        }
-    }
-
-    private void RefreshSnapshotsAsync()
-    {
-        foreach (var scene in Scenes)
-        {
-            // Minis never render live captures. While the Live screen is staged
-            // (being previewed) its mini shows the green placeholder; unstaged,
-            // it shows the stored default art. Real-time surface = center only.
-            var stagedLive = ReferenceEquals(scene, StagedScene)
-                && SceneCatalog.Is(scene.Name, SceneCatalog.Live);
-            var img = stagedLive ? null : LoadBackgroundImage(scene);
-            if (img != null)
-                scene.Snapshot = img;
-            else if (scene.Snapshot == null || stagedLive)
-                scene.Snapshot = CreatePlaceholderSnapshot(scene.Name);
-        }
-    }
-
-    internal static System.Windows.Media.Imaging.BitmapSource? LoadBackgroundImage(Scene scene)
-    {
-        var bg = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-        if (bg != null && !bg.UseDefaultBackground
-            && !string.IsNullOrWhiteSpace(bg.CustomBackgroundPath)
-            && System.IO.File.Exists(bg.CustomBackgroundPath))
-        {
-            try
-            {
-                var bitmap = new System.Windows.Media.Imaging.BitmapImage();
-                bitmap.BeginInit();
-                bitmap.UriSource = new Uri(bg.CustomBackgroundPath);
-                bitmap.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
-                bitmap.EndInit();
-                bitmap.Freeze();
-                return bitmap;
-            }
-            catch { /* fall through to AssetId */ }
-        }
-        if (bg != null && !string.IsNullOrWhiteSpace(bg.AssetId))
-            return ImageCache.Get(bg.AssetId);
-        return null;
-    }
-
-    private static BitmapSource CreatePlaceholderSnapshot(string sceneName)
-    {
-        var colors = new Dictionary<string, System.Windows.Media.Brush>(StringComparer.OrdinalIgnoreCase)
-        {
-            ["Starting"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(233, 69, 96)),
-            ["Live"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(34, 197, 94)),
-            ["BRB"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(234, 179, 8)),
-            ["Chat"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(59, 130, 246)),
-            ["Ending"] = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(168, 85, 247)),
-        };
-        var brush = colors.TryGetValue(sceneName, out var c) ? c
-            : new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromRgb(60, 60, 80));
-        var dv = new System.Windows.Media.DrawingVisual();
-        using (var ctx = dv.RenderOpen())
-        {
-            ctx.DrawRectangle(brush, null, new System.Windows.Rect(0, 0, 320, 180));
-            var ft = new System.Windows.Media.FormattedText(
-                sceneName,
-                System.Globalization.CultureInfo.InvariantCulture,
-                System.Windows.FlowDirection.LeftToRight,
-                new System.Windows.Media.Typeface("Segoe UI"),
-                18,
-                System.Windows.Media.Brushes.White,
-                96);
-            ctx.DrawText(ft, new System.Windows.Point(160 - ft.Width / 2, 90 - ft.Height / 2));
-        }
-        var rtb = new System.Windows.Media.Imaging.RenderTargetBitmap(
-            320, 180, 96, 96, System.Windows.Media.PixelFormats.Pbgra32);
-        rtb.Render(dv);
-        rtb.Freeze();
-        return rtb;
-    }
-
     public StreamHealth CurrentHealth
     {
         get => _currentHealth;
@@ -1313,11 +1130,6 @@ public partial class MainViewModel : ViewModelBase
     public ICommand ToggleElementVisibilityCommand { get; }
     public ICommand ChangeWebcamCommand { get; }
     public ICommand ShowWebcamCommand { get; }
-    public ICommand ChangeCaptureCommand { get; }
-    public ICommand RefreshCaptureCommand { get; }
-    public ICommand SetBackgroundDisplayCommand { get; }
-    public ICommand ToggleShowDesktopCommand { get; }
-    public ICommand BrowseBackgroundCommand { get; }
     public ICommand ToggleMicMuteCommand { get; }
     public ICommand ToggleGameMuteCommand { get; }
     public ICommand OpenMicPickerCommand { get; }
@@ -1635,155 +1447,6 @@ public partial class MainViewModel : ViewModelBase
         WebcamError = $"Webcam offline: {message}";
     }
 
-    // ─── Screen background capture (live desktop/game) ───
-
-    private const string MonitorKeyPrefix = "monitor:";
-
-    /// <summary>Every background-enabled scene has exactly one background, kept at index 0 (bottom layer).
-    /// Returns null for a scene with <see cref="Scene.HasBackground"/> = false.</summary>
-    internal static Source? EnsureBackground(Scene scene)
-    {
-        if (!scene.HasBackground) return null;
-        var background = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-        if (background != null) return background;
-
-        background = CreateBackground(scene.Name);
-        scene.Elements.Insert(0, background);
-        return background;
-    }
-
-    /// <summary>The one Background row for a scene. Live gets the capture flavor
-    /// (Show Desktop / monitor switch / fullscreen-game detect) falling back to
-    /// live-background.jpg; every other screen is a static default-art layer.
-    /// Both are named "Background" — the user never sees capture jargon here.</summary>
-    internal static Source CreateBackground(string sceneName)
-    {
-        var isLive = SceneCatalog.Is(sceneName, SceneCatalog.Live);
-        return new Source
-        {
-            Name = "Background",
-            Type = isLive ? SourceType.DisplayCapture : SourceType.Background,
-            IsBackground = true,
-            IsEnabled = true,
-            X = 0,
-            Y = 0,
-            Width = MasterFrameWidth,
-            Height = MasterFrameHeight,
-        };
-    }
-
-    /// <summary>Heals any loaded layout to the locked Background model: exactly
-    /// one Background per canonical scene, correct flavor for the scene (static
-    /// art everywhere, DisplayCapture on Live only), at index 0, named
-    /// "Background". Duplicates and stale rows are dropped; missing ones seeded;
-    /// non-canonical scenes get HasBackground=false and lose any backgrounds.</summary>
-    internal static void NormalizeBackgrounds(IEnumerable<Scene> scenes)
-    {
-        foreach (var scene in scenes)
-        {
-            if (!SceneCatalog.HasBackground(scene.Name))
-            {
-                scene.HasBackground = false;
-                foreach (var stale in scene.Elements.OfType<Source>().Where(s => s.IsBackground).ToList())
-                    scene.Elements.Remove(stale);
-                continue;
-            }
-
-            scene.HasBackground = true;
-            var isLive = SceneCatalog.Is(scene.Name, SceneCatalog.Live);
-            var wantedType = isLive ? SourceType.DisplayCapture : SourceType.Background;
-
-            var candidates = scene.Elements.OfType<Source>().Where(s => s.IsBackground).ToList();
-            var keep = candidates.FirstOrDefault(b => b.Type == wantedType) ?? candidates.FirstOrDefault();
-
-            foreach (var extra in candidates.Where(b => !ReferenceEquals(b, keep)))
-                scene.Elements.Remove(extra);
-
-            if (keep == null)
-            {
-                keep = CreateBackground(scene.Name);
-                scene.Elements.Insert(0, keep);
-            }
-
-            // Source.Type's setter derives IsBackground from the enum, so a
-            // flavor correction must re-assert the flag afterwards.
-            if (keep.Type != wantedType)
-            {
-                keep.Type = wantedType;
-                keep.IsBackground = true;
-            }
-
-            keep.Name = "Background";
-            keep.IsEnabled = true;
-
-            var index = scene.Elements.IndexOf(keep);
-            if (index > 0)
-                scene.Elements.Move(index, 0);
-        }
-    }
-
-    // Only the Live screen's background is a real-time surface. Every other
-    // lookup below (auto-capture, focus hooks, refresh) must ignore the static
-    // default-art rows so they can never start a desktop capture session.
-    private IEnumerable<Source> AllBackgrounds()
-        => Scenes.Where(s => SceneCatalog.Is(s.Name, SceneCatalog.Live))
-            .SelectMany(s => s.Elements.OfType<Source>().Where(x => x.IsBackground));
-
-    // Full-screen game on its monitor, else null (static bg fallback — no
-    // infinity mirror). Called at launch (from ReacquireScreenCaptures, before
-    // the window steals focus) and on focus regain (RefreshBackgroundAutoCapture).
-    // When a background has ShowDesktop=true, returns the primary monitor instead
-    // of null so the desktop is always visible.
-    private string? ResolveAutoCaptureKey()
-    {
-        var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
-        if (gameMonitor != null)
-            return $"{MonitorKeyPrefix}{gameMonitor}";
-
-        if (AllBackgrounds().Any(b => b.ShowDesktop))
-            return $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
-        return null;
-    }
-
-    // After a layout load / file open: make sure every background-enabled scene
-    // has a background, give any background without a persisted key the auto-detected
-    // one, then acquire one capture per unique background key. ScreenCaptureManager
-    // refcounts by key, so every scene pointing at the same monitor shares one
-    // session. Captures no longer referenced by any scene are released.
-    private void ReacquireScreenCaptures()
-    {
-        HealBackgrounds();
-
-        var auto = ResolveAutoCaptureKey();
-        if (auto == null)
-        {
-            foreach (var background in AllBackgrounds())
-                background.CaptureKey = null;
-        }
-        else
-        {
-            foreach (var background in AllBackgrounds())
-                if (string.IsNullOrWhiteSpace(background.CaptureKey))
-                    background.CaptureKey = auto;
-        }
-
-        var keys = AllBackgrounds()
-            .Select(b => b.CaptureKey!)
-            .Where(k => !string.IsNullOrWhiteSpace(k))
-            .ToHashSet();
-
-        // A layout reload replaces the scenes; stop captures that are no longer
-        // referenced (mirrors ReacquireWebcam's device swap).
-        foreach (var stale in _liveCaptureKeys.Except(keys))
-            _ = _screenCaptureManager.ReleaseAllAsync(stale);
-        _liveCaptureKeys = keys;
-
-        foreach (var key in keys)
-            _ = _screenCaptureManager.AcquireAsync(key);
-
-        _fullScreenDetector.StartWatching();
-    }
-
     private void RegisterLoadedWebSources()
     {
         if (_webView2Manager == null) return;
@@ -1800,169 +1463,6 @@ public partial class MainViewModel : ViewModelBase
         }
     }
 
-    // ScreenCaptureManager creates the shared WriteableBitmap on the UI thread;
-    // every background pointing at that key picks it up.
-    private void OnScreenPreviewBitmapChanged(string key, WriteableBitmap bitmap)
-    {
-        var activeBackground = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-        if (activeBackground?.CaptureKey == key)
-            BackgroundImage = bitmap;
-
-        foreach (var background in AllBackgrounds().Where(b => b.CaptureKey == key))
-            background.VideoImageSource = bitmap;
-    }
-
-    // EVENT_SYSTEM_FOREGROUND fires whenever the foreground window changes.
-    // When a full-screen game appears on a different monitor than the current
-    // background, auto-redesignate. When ShowDesktop is enabled and no fullscreen
-    // game is detected, fall back to the primary monitor (desktop view).
-    private void OnFullscreenMonitorChanged(int? monitor)
-    {
-        if (monitor != null)
-        {
-            var newKey = $"{MonitorKeyPrefix}{monitor}";
-            var current = AllBackgrounds().FirstOrDefault();
-            if (current?.CaptureKey == newKey) return;
-            _ = RedesignateBackgroundAsync(newKey);
-        }
-        else if (AllBackgrounds().Any(b => b.ShowDesktop))
-        {
-            var desktopKey = $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
-            var current = AllBackgrounds().FirstOrDefault();
-            if (current?.CaptureKey == desktopKey) return;
-            _ = RedesignateBackgroundAsync(desktopKey);
-        }
-    }
-
-    // Manual refresh: the "Refresh Capture" context menu item. Reads the
-    // current foreground directly (no caching needed — the hook handles
-    // automatic detection).
-    public void RefreshBackgroundAutoCapture()
-    {
-        var detected = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
-        if (detected == null) return;
-        _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{detected}");
-    }
-
-    /// <summary>Whether the active background is in Show Desktop mode.
-    /// Bindable IsChecked property for the context menu toggle.</summary>
-    public bool BackgroundShowDesktop
-    {
-        get => StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground)?.ShowDesktop ?? false;
-        set
-        {
-            var background = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-            if (background == null || background.ShowDesktop == value) return;
-            background.ShowDesktop = value;
-            OnPropertyChanged(nameof(BackgroundShowDesktop));
-            ScheduleSave();
-            if (value)
-            {
-                _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}");
-            }
-            else
-            {
-                var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
-                if (gameMonitor != null)
-                    _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{gameMonitor}");
-                else
-                    _ = ClearBackgroundCaptureAsync();
-            }
-        }
-    }
-
-    private void ToggleBackgroundShowDesktop() => BackgroundShowDesktop = !BackgroundShowDesktop;
-
-    private void BrowseBackground()
-    {
-        var scene = StagedScene;
-        if (scene == null) return;
-        var bg = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-        if (bg == null) return;
-
-        var dlg = new Microsoft.Win32.OpenFileDialog
-        {
-            Title = "Select background image",
-            Filter = "Image files (*.jpg;*.jpeg;*.png;*.bmp)|*.jpg;*.jpeg;*.png;*.bmp|All files (*.*)|*.*",
-        };
-        if (dlg.ShowDialog() != true) return;
-
-        bg.CustomBackgroundPath = dlg.FileName;
-        bg.UseDefaultBackground = false;
-        try
-        {
-            using var fs = new System.IO.FileStream(dlg.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
-            var bytes = new byte[fs.Length];
-            fs.Read(bytes, 0, bytes.Length);
-            var assetId = AddAsset(bytes);
-            if (assetId != null)
-                bg.AssetId = assetId;
-        }
-        catch { /* non-critical */ }
-
-        UpdateActiveBackground();
-        RefreshSnapshotsAsync();
-        ScheduleSave();
-    }
-
-    /// <summary>Release the background capture so the static placeholder image shows.</summary>
-    private async Task ClearBackgroundCaptureAsync()
-    {
-        var oldKeys = AllBackgrounds()
-            .Select(b => b.CaptureKey!)
-            .Where(k => !string.IsNullOrWhiteSpace(k))
-            .ToHashSet();
-
-        foreach (var background in AllBackgrounds())
-        {
-            background.CaptureKey = null;
-            background.VideoImageSource = null;
-        }
-
-        foreach (var key in oldKeys)
-            await _screenCaptureManager.ReleaseAllAsync(key);
-
-        _liveCaptureKeys.Clear();
-        UpdateBackgroundImage();
-        ScheduleSave();
-    }
-
-    private async Task RedesignateBackgroundAsync(string newKey)
-    {
-        var oldKeys = AllBackgrounds()
-            .Select(b => b.CaptureKey!)
-            .Where(k => !string.IsNullOrWhiteSpace(k))
-            .ToHashSet();
-
-        foreach (var background in AllBackgrounds())
-            background.CaptureKey = newKey;
-
-        foreach (var oldKey in oldKeys.Where(k => k != newKey))
-            await _screenCaptureManager.ReleaseAllAsync(oldKey);
-        if (!oldKeys.Contains(newKey))
-            await _screenCaptureManager.AcquireAsync(newKey);
-        _liveCaptureKeys = new HashSet<string> { newKey };
-        UpdateBackgroundImage();
-        ScheduleSave();
-    }
-
-    // "Change Capture…": the OS GraphicsCapturePicker designates the target.
-    // Picks are transient (see ScreenCaptureSourceFactory) — a reload falls
-    // back to auto-detection.
-    public async Task ChangeBackgroundCaptureAsync()
-    {
-        var key = await _screenCaptureFactory.PickAsync();
-        if (key == null) return;
-        await RedesignateBackgroundAsync(key);
-    }
-
-    // In-app display picker: point every background at a specific monitor.
-    private void SetBackgroundCapture(DisplayInfo? display)
-    {
-        if (display == null) return;
-        _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{display.Index}");
-    }
-
     public void InitWebView2(Panel hostPanel)
     {
         _webView2Manager = new WebView2Manager(hostPanel, System.Windows.Application.Current.Dispatcher);
@@ -2013,57 +1513,6 @@ public partial class MainViewModel : ViewModelBase
         _saveDebounce.Start();
     }
 
-    // ─── Background model (TASK 25): exactly ONE Background per screen, index 0,
-    // never removable or re-addable. Static default art on Starting/BRB/Chat/Ending;
-    // on Live it's the capture-flavored row (Show Desktop / monitor switch /
-    // fullscreen-game detect) falling back to live-background.jpg. ───
-
-    private static string? DefaultBackgroundAsset(string sceneName) => sceneName switch
-    {
-        SceneCatalog.Starting => "starting-background.jpg",
-        SceneCatalog.Brb => "brb-background.jpg",
-        SceneCatalog.Chat => "chat-background.jpg",
-        SceneCatalog.Ending => "ending-background.jpg",
-        SceneCatalog.Live => "live-background.jpg",
-        _ => null,
-    };
-
-    /// <summary>Heals every scene to the locked Background model after a layout
-    /// load: keeps the correct flavor per scene at index 0 named "Background",
-    /// drops duplicates/stale rows, re-seeds missing ones.</summary>
-    private void HealBackgrounds()
-    {
-        NormalizeBackgrounds(Scenes);
-        foreach (var scene in Scenes)
-        {
-            var background = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-            if (background != null)
-                StampDefaultBackgroundAsset(background, scene.Name);
-        }
-        OnPropertyChanged(nameof(ShowSourcesEmptyHint));
-    }
-
-    /// <summary>Points a background row at its scene's shipped default art when it
-    /// carries none. A custom image (Browse…) always wins and is never overwritten.</summary>
-    private void StampDefaultBackgroundAsset(Source background, string sceneName)
-    {
-        if (!string.IsNullOrWhiteSpace(background.AssetId)) return;
-        if (!background.UseDefaultBackground && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)) return;
-        var asset = DefaultBackgroundAsset(sceneName);
-        if (asset == null) return;
-
-        try
-        {
-            var uri = new Uri($"pack://application:,,,/Assets/{asset}", UriKind.Absolute);
-            using var stream = Application.GetResourceStream(uri)?.Stream;
-            if (stream == null) return;
-            using var ms = new MemoryStream();
-            stream.CopyTo(ms);
-            background.AssetId = AddAsset(ms.ToArray());
-        }
-        catch { /* non-critical — the app works without default art */ }
-    }
-
     private void BeginEditElement(SceneElement? element)
     {
         if (element == null) return;

ViewModels/index.md

@@ -38,12 +38,24 @@ Progress (Commit N/12 · tag):
   `RefreshHotkeyLabels`, scene-gating hints, `MissingScenes`/`ShowAddScene`/
   `CanChangeBackground`, scene wiring `OnScenesChanged`/`WireScene`/`UnwireScene`,
   `AddScene`).
+- **Commit 4/12 · `refactor-commit-4`: Background landed** → `MainViewModel.Background.cs`
+  (background model `EnsureBackground`/`CreateBackground`/`NormalizeBackgrounds`/
+  `HealBackgrounds`/`StampDefaultBackgroundAsset`, display picker `Displays` +
+  `SetBackgroundCapture`, screen capture `ReacquireScreenCaptures`/
+  `ResolveAutoCaptureKey`/`RedesignateBackgroundAsync`/`ClearBackgroundCaptureAsync`/
+  `OnScreenPreviewBitmapChanged`/`OnFullscreenMonitorChanged`/
+  `RefreshBackgroundAutoCapture`/`BackgroundShowDesktop`, preview fns
+  `ActiveBackgroundImage`/`BackgroundImage`/`UpdateActiveBackground`/
+  `UpdateBackgroundImage`/`RefreshSnapshotsAsync`/`LoadBackgroundImage`,
+  `ChangeCaptureCommand`/`RefreshCaptureCommand`/`SetBackgroundDisplayCommand`/
+  `ToggleShowDesktopCommand`/`BrowseBackgroundCommand`). `ShowPreviewPlaceholder`
+  stays in core.
 
 - Core file keeps: fields, ctor, `Shutdown`/`SaveLayoutNow`/`ScheduleSave`/`LoadLayout`,
   `SetPanel`/`ShowOverlay`/`ShowLicenses`, `CreateBrush`, `OpenUrl`/`ComposeEmail`,
   `SubmitBug`/`SubmitFeature`, window-geometry pass-through.
-- Partials: `Account` ✔ (Commit 1), `License` ✔ (Commit 2), `Scenes` ✔ (Commit 3), `Background` (background model + screen
+- Partials: `Account` ✔ (Commit 1), `License` ✔ (Commit 2), `Scenes` ✔ (Commit 3), `Background` ✔ (Commit 4),
-  capture + display picker), `Webcam` (webcam identity + per-scene configs + captures),
+  `Webcam` (webcam identity + per-scene configs + captures),
   `Audio` (mic + game bars + TRAX), `Trax` (music player), `Socials` (social bar + dialog),
   `Streaming` (go-live/record + health + quality tiers + media source pipeline),
   `Chat` (YouTube chat + mock preview + chatbox render), `Overlays` (settings/bug/feature/about