diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 4578f20..ba1c021 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -1002,10 +1002,23 @@ public sealed class GameWindow : IDisposable
                 ae.CurrFrame = ae.LowFrame;
             }
 
-            int frameIdx = (int)ae.CurrFrame;
-            if (frameIdx < 0 || frameIdx >= ae.Animation.PartFrames.Count)
+            // Phase 6.5: blend between adjacent keyframes using the fractional
+            // part of CurrFrame so the animation is smooth at any framerate
+            // instead of snapping to integer frame indices.
+            int frameIdx = (int)Math.Floor(ae.CurrFrame);
+            if (frameIdx < ae.LowFrame || frameIdx > ae.HighFrame
+                || frameIdx >= ae.Animation.PartFrames.Count)
                 frameIdx = ae.LowFrame;
+
+            int nextIdx = frameIdx + 1;
+            if (nextIdx > ae.HighFrame || nextIdx >= ae.Animation.PartFrames.Count)
+                nextIdx = ae.LowFrame;  // cycle wraps within [LowFrame, HighFrame]
+
+            float t = ae.CurrFrame - frameIdx;
+            if (t < 0f) t = 0f; else if (t > 1f) t = 1f;
+
             var partFrames = ae.Animation.PartFrames[frameIdx].Frames;
+            var partFramesNext = ae.Animation.PartFrames[nextIdx].Frames;
 
             int partCount = ae.PartTemplate.Count;
             var newMeshRefs = new List<AcDream.Core.World.MeshRef>(partCount);
@@ -1015,18 +1028,25 @@ public sealed class GameWindow : IDisposable
 
             for (int i = 0; i < partCount; i++)
             {
-                // Frame source: the animation's per-part transform when
-                // the index is in range, otherwise identity (parts that
-                // outnumber the animation's bone list — rare but defensive).
-                DatReaderWriter.Types.Frame frame;
+                // Slerp between the current and next keyframe per part.
+                // Out-of-range parts get an identity transform — defensive
+                // for setups whose part count exceeds the animation's bone
+                // count.
+                System.Numerics.Vector3 origin;
+                System.Numerics.Quaternion orientation;
                 if (i < partFrames.Count)
-                    frame = partFrames[i];
+                {
+                    var f0 = partFrames[i];
+                    var f1 = i < partFramesNext.Count ? partFramesNext[i] : f0;
+                    origin = System.Numerics.Vector3.Lerp(f0.Origin, f1.Origin, t);
+                    orientation = System.Numerics.Quaternion.Slerp(f0.Orientation, f1.Orientation, t);
+                }
                 else
-                    frame = new DatReaderWriter.Types.Frame
-                    {
-                        Origin = System.Numerics.Vector3.Zero,
-                        Orientation = System.Numerics.Quaternion.Identity,
-                    };
+                {
+                    origin = System.Numerics.Vector3.Zero;
+                    orientation = System.Numerics.Quaternion.Identity;
+                }
+                var frame = new DatReaderWriter.Types.Frame { Origin = origin, Orientation = orientation };
 
                 // Per-part default scale from the Setup, matching SetupMesh.Flatten's
                 // composition order: scale → rotate → translate.