diff --git a/src/AcDream.App/Rendering/CellVisibility.cs b/src/AcDream.App/Rendering/CellVisibility.cs
index f3e0c55..bcca4ec 100644
--- a/src/AcDream.App/Rendering/CellVisibility.cs
+++ b/src/AcDream.App/Rendering/CellVisibility.cs
@@ -330,6 +330,21 @@ public sealed class CellVisibility
                local.Z <= cell.LocalBoundsMax.Z + PointInCellEpsilon;
     }
 
+    /// <summary>
+    /// Brute-force scan of every loaded cell to test whether
+    /// <paramref name="worldPoint"/> is inside any of them. Does not touch
+    /// the camera cache (<see cref="_lastCameraCell"/>), so this is safe
+    /// to call alongside <see cref="ComputeVisibility"/> in the same frame
+    /// for a different position (e.g. player position when the camera is
+    /// in third-person chase mode).
+    /// </summary>
+    public bool IsInsideAnyCell(Vector3 worldPoint)
+    {
+        foreach (var cell in _cellLookup.Values)
+            if (PointInCell(worldPoint, cell)) return true;
+        return false;
+    }
+
     // ------------------------------------------------------------------
     // GetVisibleCells (BFS)
     // ------------------------------------------------------------------
diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 6f87a61..13a660c 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -6848,6 +6848,19 @@ public sealed class GameWindow : IDisposable
             var visibility = _cellVisibility.ComputeVisibility(camPos);
             bool cameraInsideCell = visibility?.CameraCell is not null;
 
+            // Lighting decisions (sun zeroed, indoor ambient applied) must
+            // track the PLAYER's cell, not the camera's. In third-person
+            // chase mode the camera enters interiors before the player body
+            // does, so a camera-based trigger flips the scene to indoor
+            // lighting prematurely. Retail's CellManager::ChangePosition
+            // @ 0x004559B0 reads CObjCell::seen_outside on the player's
+            // current cell — that's the semantics we want here. When the
+            // player isn't in player mode (orbit / fly debug camera) we
+            // fall back to the camera trigger.
+            bool playerInsideCell = (_playerMode && _playerController is not null)
+                ? _cellVisibility.IsInsideAnyCell(_playerController.Position)
+                : cameraInsideCell;
+
             // Phase C.1: tick retail PhysicsScript particle hooks. Named
             // retail decomp confirms SkyObject.PesObjectId is copied by
             // SkyDesc::GetSky but ignored by GameSky, so the sky-PES path is
@@ -6861,7 +6874,7 @@ public sealed class GameWindow : IDisposable
             // the scene-lighting UBO once per frame. Every shader that
             // consumes binding=1 reads the same data for the rest of the
             // frame — terrain, static mesh, instanced mesh, sky.
-            UpdateSunFromSky(kf, cameraInsideCell);
+            UpdateSunFromSky(kf, playerInsideCell);
             Lighting.Tick(camPos);
             var ubo = AcDream.Core.Lighting.SceneLightingUbo.Build(
                 Lighting, in atmo, camPos, (float)WorldTime.DayFraction);
@@ -8326,15 +8339,18 @@ public sealed class GameWindow : IDisposable
     /// Indoor brightness then comes from per-cell point lights
     /// (Setup.Lights on the cell's static objects, registered through
     /// <see cref="AcDream.Core.Lighting.LightingHookSink"/>).
+    /// The trigger is the PLAYER's cell, not the camera's — third-person
+    /// chase camera enters interiors before the player body does, and
+    /// retail keys lighting off the player position.
     /// </summary>
-    private void UpdateSunFromSky(AcDream.Core.World.SkyKeyframe kf, bool cameraInsideCell)
+    private void UpdateSunFromSky(AcDream.Core.World.SkyKeyframe kf, bool playerInsideCell)
     {
         // Sun direction: points FROM the sun TOWARDS the world. Our
         // shader does dot(N, -forward) so a positive N·L means the
         // surface faces the sun.
         var sunToWorld = -AcDream.Core.World.SkyStateProvider.SunDirectionFromKeyframe(kf);
 
-        if (cameraInsideCell)
+        if (playerInsideCell)
         {
             // Indoor default — retail's flat 0.2 neutral ambient, sun
             // zeroed. See xref to retail decomp in the doc comment above.