diff --git a/src/AcDream.App/Rendering/Wb/EnvCellRenderer.cs b/src/AcDream.App/Rendering/Wb/EnvCellRenderer.cs
index cf713c0..4820f51 100644
--- a/src/AcDream.App/Rendering/Wb/EnvCellRenderer.cs
+++ b/src/AcDream.App/Rendering/Wb/EnvCellRenderer.cs
@@ -613,6 +613,26 @@ public sealed unsafe class EnvCellRenderer : IDisposable
             _shader.Use();
             _poolIndex = snapshot.BatchedByCell.Count; // reset point (mirrors WB line 405)
 
+            // FIX 2026-05-28: invalidate static GL-state caches at start of Render.
+            // Mirrors WB EnvCellRenderManager.cs:404-410:
+            //   CurrentVAO = 0; CurrentIBO = 0; CurrentAtlas = 0;
+            //   CurrentInstanceBuffer = 0; CurrentCullMode = null;
+            //
+            // These caches let SetCullMode / BindVertexArray skip redundant GL
+            // calls when the state is already correct. BUT: between two Render()
+            // invocations, OTHER consumers (WbDrawDispatcher, terrain, the
+            // RenderInsideOutAcdream stencil pipeline) change the actual GL
+            // state without updating these caches. The cache then lies, and
+            // the per-batch SetCullMode in RenderModernMDIInternal skips its
+            // glCullFace call — leaving stale cull state from the prior
+            // consumer. For a cottage with mixed CullMode batches, half the
+            // walls end up culled and the user sees "missing walls".
+            //
+            // Forcing the cache to null/0 at entry guarantees each Render call
+            // re-establishes the GL state it expects.
+            _currentVao = 0;
+            _currentCullMode = null;
+
             // WB EnvCellRenderManager.cs:406-409: uniform state setup.
             _shader.SetInt("uRenderPass", (int)renderPass);
             _shader.SetInt("uFilterByCell", 0);