feat: harden isolated Tornado test workflow

src/MBN_STOCK_WEBVIEW.Playout/PlayoutEngineFactory.cs

@@ -28,4 +28,51 @@ public static class PlayoutEngineFactory
             new EnvironmentLiveAuthorization(),
             TimeProvider.System);
     }
+
+    /// <summary>
+    /// Applies the same fail-closed Test-mode configuration, scene-root, file-name and
+    /// allowlist validation used by the runtime before a diagnostic tool creates an engine.
+    /// This method never creates a dispatcher or activates COM.
+    /// </summary>
+    public static void ValidateIsolatedTestCommand(
+        PlayoutOptions options,
+        IEnumerable<PlayoutCue> cues)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        ArgumentNullException.ThrowIfNull(cues);
+
+        if (options.Mode != PlayoutMode.Test || options.TrustedLiveOutputEnabled)
+        {
+            throw new PlayoutConfigurationException(
+                "The isolated test command requires Test mode with live output disabled.");
+        }
+
+        var validated = ValidatedPlayoutOptions.Create(options);
+        foreach (var cue in cues)
+        {
+            if (cue is null)
+            {
+                throw new PlayoutConfigurationException(
+                    "The isolated test command contains an invalid scene.");
+            }
+
+            PlayoutCue resolved;
+            try
+            {
+                resolved = validated.ResolveCue(cue);
+            }
+            catch (PlayoutRequestException exception)
+            {
+                throw new PlayoutConfigurationException(
+                    "The isolated test command contains an invalid scene.",
+                    exception);
+            }
+
+            if (!validated.IsTestSceneAllowed(resolved))
+            {
+                throw new PlayoutConfigurationException(
+                    "The isolated test command contains a scene that is not allowlisted.");
+            }
+        }
+    }
 }