diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index e03217b..75857de 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -331,6 +331,17 @@ public sealed class GameWindow : IDisposable
         /// </summary>
         public bool Airborne;
 
+        /// <summary>
+        /// Per-remote position-waypoint queue + catch-up math (retail's
+        /// CPhysicsObj::InterpolateTo + InterpolationManager::adjust_offset).
+        /// Replaces the hard-snap-then-Euler-extrapolate path when
+        /// <c>ACDREAM_INTERP_MANAGER=1</c> — see Phase L.3.1 spec at
+        /// <c>docs/superpowers/specs/2026-05-02-l3-remote-entity-motion-design.md</c>.
+        /// Field exists from Task 3 onwards; consumed in Tasks 4 + 5.
+        /// </summary>
+        public AcDream.Core.Physics.InterpolationManager Interp { get; } =
+            new AcDream.Core.Physics.InterpolationManager();
+
         public RemoteMotion()
         {
             Body = new AcDream.Core.Physics.PhysicsBody