fix: complete retail parity stability pass

src/AcDream.App/Rendering/WorldRenderFrameBuilder.cs

@@ -462,6 +462,7 @@ internal sealed class RuntimeWorldFrameEnvironmentPreparation
     private readonly SceneLightingUboBinding? _lightingUbo;
     private readonly IWorldRenderRangeSource _ranges;
     private readonly SkyPesFrameController? _skyPes;
+    private readonly Func<bool> _persistentDaylight;
     private readonly HashSet<uint> _visibleCells = [];
     private bool _visibleCellsValid;
 
@@ -473,7 +474,8 @@ internal sealed class RuntimeWorldFrameEnvironmentPreparation
         EnvCellRenderer? environmentCells,
         SceneLightingUboBinding? lightingUbo,
         IWorldRenderRangeSource ranges,
-        SkyPesFrameController? skyPes)
+        SkyPesFrameController? skyPes,
+        Func<bool>? persistentDaylight = null)
     {
         _options = options ?? throw new ArgumentNullException(nameof(options));
         _worldTime = worldTime ?? throw new ArgumentNullException(nameof(worldTime));
@@ -483,6 +485,7 @@ internal sealed class RuntimeWorldFrameEnvironmentPreparation
         _lightingUbo = lightingUbo;
         _ranges = ranges ?? throw new ArgumentNullException(nameof(ranges));
         _skyPes = skyPes;
+        _persistentDaylight = persistentDaylight ?? (static () => false);
     }
 
     public void Prepare(
@@ -500,7 +503,14 @@ internal sealed class RuntimeWorldFrameEnvironmentPreparation
             activeDayGroup,
             camera.Position);
 
-        UpdateSunFromSky(foundation.Sky, roots.PlayerInsideCell);
+        // LScape::set_landscape_lighting @0x005054D0 keeps the live sky/fog
+        // clock but, when PersistentAtDay is set, asks the active region for
+        // lighting at exactly 0.5 (noon). Do not pin WorldTime.DayFraction:
+        // clouds, celestial objects, fog, and scripts must keep advancing.
+        SkyKeyframe landscapeLighting = _persistentDaylight()
+            ? _worldTime.SkyAtDayFraction(0.5f)
+            : foundation.Sky;
+        UpdateSunFromSky(landscapeLighting, roots.PlayerInsideCell);
         _lighting.UpdateViewerLight(roots.PlayerViewPosition);
         _lighting.Tick(camera.Position);
         _lighting.BuildPointLightSnapshot(