diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index a485ea5..351bf9b 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -72,6 +72,11 @@ public sealed class GameWindow : IDisposable
     private int _liveDropReasonNoSetup;
     private int _liveDropReasonSetupDatMissing;
     private int _liveDropReasonNoMeshRefs;
+    // Phase 6.4 animation-registration diagnostics
+    private int _liveAnimRejectNoCycle;
+    private int _liveAnimRejectFramerate;
+    private int _liveAnimRejectSingleFrame;
+    private int _liveAnimRejectPartFrames;
 
     public GameWindow(string datDir, WorldGameState worldGameState, WorldEvents worldEvents)
     {
@@ -449,9 +454,18 @@ public sealed class GameWindow : IDisposable
                             // the WorldEntity at identity so the renderer's
                             // model = PartTransform * entityRoot = cellTransform * I
                             // gives the correctly positioned cell mesh.
+                            //
+                            // Z lift: buildings sit ON the terrain mesh, so the ground
+                            // floor of every building is coincident in Z with the terrain
+                            // polygon beneath it. Without a bias the two fight for the
+                            // same depth and flicker as the camera moves. A small lift
+                            // (2 cm) is invisible from human scale but breaks the tie
+                            // cleanly in the cell mesh's favor.
+                            var cellOrigin = envCell.Position.Origin + lbOffset
+                                + new System.Numerics.Vector3(0f, 0f, 0.02f);
                             var cellTransform =
                                 System.Numerics.Matrix4x4.CreateFromQuaternion(envCell.Position.Orientation) *
-                                System.Numerics.Matrix4x4.CreateTranslation(envCell.Position.Origin + lbOffset);
+                                System.Numerics.Matrix4x4.CreateTranslation(cellOrigin);
 
                             var cellMeshRef = new AcDream.Core.World.MeshRef(envCellId, cellTransform);
 
@@ -921,6 +935,17 @@ public sealed class GameWindow : IDisposable
         // Phase 6.4: register for per-frame playback if we resolved a real
         // cycle with a non-zero framerate and at least two frames in the
         // cycle (single-frame poses are static and don't need ticking).
+        // Diagnostic: log why we did / didn't register so we can tell
+        // which entities fall through the filter.
+        if (idleCycle is null)
+            _liveAnimRejectNoCycle++;
+        else if (idleCycle.Framerate == 0f)
+            _liveAnimRejectFramerate++;
+        else if (idleCycle.HighFrame <= idleCycle.LowFrame)
+            _liveAnimRejectSingleFrame++;
+        else if (idleCycle.Animation.PartFrames.Count <= 1)
+            _liveAnimRejectPartFrames++;
+
         if (idleCycle is not null && idleCycle.Framerate != 0f
             && idleCycle.HighFrame > idleCycle.LowFrame
             && idleCycle.Animation.PartFrames.Count > 1)
@@ -950,6 +975,10 @@ public sealed class GameWindow : IDisposable
         // waiting for a graceful shutdown.
         if (_liveSpawnReceived % 20 == 0)
         {
+            Console.WriteLine(
+                $"live: animated={_animatedEntities.Count} " +
+                $"animReject: noCycle={_liveAnimRejectNoCycle} fr0={_liveAnimRejectFramerate} " +
+                $"1frame={_liveAnimRejectSingleFrame} partFrames={_liveAnimRejectPartFrames}");
             Console.WriteLine(
                 $"live: summary recv={_liveSpawnReceived} hydrated={_liveSpawnHydrated} " +
                 $"drops: noPos={_liveDropReasonNoPos} noSetup={_liveDropReasonNoSetup} " +