diff --git a/src/AcDream.App/Rendering/Shaders/portal_stencil.vert b/src/AcDream.App/Rendering/Shaders/portal_stencil.vert
index bdd118f..a10eded 100644
--- a/src/AcDream.App/Rendering/Shaders/portal_stencil.vert
+++ b/src/AcDream.App/Rendering/Shaders/portal_stencil.vert
@@ -10,6 +10,9 @@ layout(location = 0) in vec3 aPosition;
 
 uniform mat4 uViewProjection;
 
+// Note: no pos.w clamp — coplanar-camera degenerate is accepted per spec.
+// If stencil artifacts appear when the camera straddles an exit portal plane,
+// re-introduce the clamp from WB's PortalStencil.vert.
 void main()
 {
     gl_Position = uViewProjection * vec4(aPosition, 1.0);