Screen backdrop (schema v5/v6) + five-scene catalog + webcam polish: live desktop/game capture as a permanent non-deletable bottom layer (Source.IsBackdrop), auto full-screen game detection (Win32FullScreenDetector) else primary display, GraphicsCapturePicker re-designation, refcounted shared ScreenCaptureManager, Live-only backdrop by policy (HasBackdrop + v5-v6 backfill + EnforceBackdropPolicy, checkbox gone), SceneCatalog (Starting/Live/BRB/Chat/Ending) with + button re-adding missing scenes, webcam mid-session transparent-container fix (GetPreviewBitmap propagation), Chat half-screen-area cap, 'Add Webcam' always opens the picker (SwapWebcamIdentityAsync, no silent resurrect), WindowsRuntimeMarshal frame-read + 5s-throttled errors, docs updated, tests (65 passing)

Services/CameraManager.cs

@@ -150,6 +150,18 @@ public sealed class CameraManager : IDisposable
             return _sessions.TryGetValue(deviceId, out var session) ? session.LatestFrame : null;
     }
 
+    /// <summary>
+    /// The shared WriteableBitmap for a running session, or null when the camera
+    /// hasn't produced its first frame yet. <see cref="PreviewBitmapChanged"/> only
+    /// fires once (first frame), so configs created after the session started must
+    /// pick the bitmap up from here.
+    /// </summary>
+    public WriteableBitmap? GetPreviewBitmap(string deviceId)
+    {
+        lock (_gate)
+            return _sessions.TryGetValue(deviceId, out var session) ? session.PreviewBitmap : null;
+    }
+
     public void Dispose()
     {
         List<CameraSession> sessions;