feat: add native runtime settings

tests/MBN_STOCK_WEBVIEW.Playout.Tests/PlayoutOptionsLoaderTests.cs

@@ -95,6 +95,53 @@ public sealed class PlayoutOptionsLoaderTests
         Assert.Equal("C:\\explicit-cuts", options.SceneDirectory);
     }
 
+    [Fact]
+    public void ApplyOperatorAssetOverrides_ChangesOnlyNativeAssetRoots()
+    {
+        var options = new PlayoutOptions
+        {
+            Mode = PlayoutMode.Live,
+            Host = "protected-host",
+            SceneDirectory = "C:\\json-cuts",
+            LegacyBackgroundDirectory = "C:\\json-backgrounds",
+            TrustedLiveOutputEnabled = true,
+            TestSceneAllowlist = ["5001"]
+        };
+
+        PlayoutOptionsLoader.ApplyOperatorAssetOverrides(
+            options,
+            " C:\\operator-cuts ",
+            " C:\\operator-backgrounds ");
+
+        Assert.Equal("C:\\operator-cuts", options.SceneDirectory);
+        Assert.Equal("C:\\operator-backgrounds", options.LegacyBackgroundDirectory);
+        Assert.Equal(PlayoutMode.Live, options.Mode);
+        Assert.Equal("protected-host", options.Host);
+        Assert.True(options.TrustedLiveOutputEnabled);
+        Assert.Equal(["5001"], options.TestSceneAllowlist);
+    }
+
+    [Fact]
+    public void Load_EnvironmentAssetRootsOverrideNativeOperatorSelection()
+    {
+        using var environment = ClearedEnvironment()
+            .Set("MBN_STOCK_PLAYOUT_SCENE_DIRECTORY", "C:\\environment-cuts")
+            .Set(
+                "MBN_STOCK_PLAYOUT_LEGACY_BACKGROUND_DIRECTORY",
+                "C:\\environment-backgrounds");
+        using var file = TemporaryJsonFile.Missing();
+
+        var options = PlayoutOptionsLoader.Load(
+            file.Path,
+            "C:\\operator-cuts",
+            "C:\\operator-backgrounds");
+
+        Assert.Equal("C:\\environment-cuts", options.SceneDirectory);
+        Assert.Equal("C:\\environment-backgrounds", options.LegacyBackgroundDirectory);
+        Assert.Equal(PlayoutMode.DryRun, options.Mode);
+        Assert.False(options.TrustedLiveOutputEnabled);
+    }
+
     [Fact]
     public void Load_EnvironmentOverridesJson_ExceptFileOnlySafetyGates()
     {