fix: reuse scenes for on-air refresh

src/MBN_STOCK_WEBVIEW.Playout/Interop/DynamicK3dSession.cs

@@ -413,9 +413,16 @@ internal sealed class DynamicK3dSession : IK3dGuardedConnectSession
 
         try
         {
-            nextScene = new SceneReference(
-                InvokeRequired(engine, "LoadScene", cue.SceneFile, cue.SceneName),
-                cue.SceneName);
+            // MainForm refreshes the selected DTO immediately before TAKE IN and
+            // Page NEXT can target the alias already on air. Tornado2 rejects a
+            // second LoadScene for an alias it still owns, so mutate and re-Prepare
+            // the retained loaded scene instead of creating a duplicate alias.
+            nextScene =
+                ReusableScene(_preparedScene, cue.SceneName) ??
+                ReusableScene(_currentScene, cue.SceneName) ??
+                new SceneReference(
+                    InvokeRequired(engine, "LoadScene", cue.SceneFile, cue.SceneName),
+                    cue.SceneName);
             if (outputChannel.HasValue)
             {
                 Invoke(nextScene.Value, "SetOutputChannelIndex", outputChannel.GetValueOrDefault());
@@ -548,10 +555,16 @@ internal sealed class DynamicK3dSession : IK3dGuardedConnectSession
 
         try
         {
-            // MainForm.timer1_Tick replays the current layout before entering
-            // Show_PlayList(idx: 1), then prepares and plays the mutated scene again.
-            InvokeTrackedPlay(layoutIndex);
             playingScene = InvokeRequired(player, "GetPlayingScene", layoutIndex);
+
+            foreach (var mutation in cue.Mutations ?? [])
+            {
+                if (IsBeforeTransactionSceneSetupMutation(mutation))
+                {
+                    ApplySceneSetupMutation(playingScene, mutation);
+                }
+            }
+
             Invoke(engine, "BeginTransaction");
             transactionStarted = true;
 
@@ -562,11 +575,12 @@ internal sealed class DynamicK3dSession : IK3dGuardedConnectSession
 
             foreach (var mutation in cue.Mutations ?? [])
             {
-                // The legacy idx == 1 path updates the playing scene in place. It does not
-                // reapply scene-level background setup or the scene transition effect.
-                if (!IsSceneLevelMutation(mutation))
+                // Match Show_PlayList(idx: 1): common background setup runs before the
+                // transaction, while builder-owned setup and object changes keep their
+                // explicit in-transaction ordering.
+                if (!IsBeforeTransactionSceneSetupMutation(mutation))
                 {
-                    ApplyMutation(playingScene, mutation);
+                    ApplyTransactionMutation(playingScene, mutation);
                 }
             }
 
@@ -1080,6 +1094,14 @@ internal sealed class DynamicK3dSession : IK3dGuardedConnectSession
         }
     }
 
+    private static SceneReference? ReusableScene(
+        SceneReference? scene,
+        string sceneName) =>
+        scene is not null &&
+        string.Equals(scene.Name, sceneName, StringComparison.OrdinalIgnoreCase)
+            ? scene
+            : null;
+
     private void MoveAllScenesToPendingTakeOut()
     {
         AddDistinctScene(_pendingTakeOutScenes, _preparedScene);