diff --git a/src/AcDream.Core/Physics/TransitionTypes.cs b/src/AcDream.Core/Physics/TransitionTypes.cs
index 535ceb7..f514046 100644
--- a/src/AcDream.Core/Physics/TransitionTypes.cs
+++ b/src/AcDream.Core/Physics/TransitionTypes.cs
@@ -2383,7 +2383,7 @@ public sealed class Transition
                 // ACE: Sphere.IntersectsSphere handles CylSphere objects via
                 // the same 6-path dispatcher. For now we keep the swept-sphere
                 // cylinder test which matches the retail CylSphere behavior.
-                result = CylinderCollision(obj, sp);
+                result = CylinderCollision(obj, sp, engine);
 
                 // A6.P4 door investigation (2026-05-24): log every Cylinder
                 // shadow tested. Tells us whether the broadphase returned
@@ -2521,13 +2521,33 @@ public sealed class Transition
     }
 
     /// <summary>
-    /// Cylinder collision test for CylSphere objects (tree trunks, rock pillars, NPCs).
-    /// Applies a horizontal wall-slide response when the sphere overlaps the
-    /// cylinder, matching the BSP path 5/6 response for consistent behavior.
+    /// Cylinder collision test for CylSphere objects (tree trunks, rock pillars, NPCs,
+    /// door foot-colliders). For Contact-grounded movers, attempts to step over short
+    /// cylinders (retail-faithful CCylSphere::step_sphere_up). For airborne movers,
+    /// movers already stepping, or cylinders too tall to step over, applies a
+    /// horizontal wall-slide response.
+    ///
+    /// <para>
+    /// A6.P6 (2026-05-25): the step-over path matches retail's
+    /// <c>CCylSphere::step_sphere_up</c> at
+    /// <c>acclient_2013_pseudo_c.txt:324516-324538</c>. The door's foot
+    /// cylinder (h=0.20m, r=0.10m) is too tall for the static slide to
+    /// produce smooth sliding along the slab — the radial push-out
+    /// fires as a "phantom collision" at the door's center when the
+    /// sphere is touching the slab face and the cyl is just within reach.
+    /// Retail steps the sphere over the cyl (succeeds when
+    /// <c>step_up_height &gt;= sphere.radius + cyl.height - offset.z</c>),
+    /// which lets the sphere walk past the cyl without the radial push.
+    /// On step-up failure (cyl too tall, no walkable surface beyond),
+    /// falls back to <c>step_up_slide</c> — the same crease-projection
+    /// slide the BSP path uses, which produces smoother behavior than
+    /// the radial push.
+    /// </para>
     /// </summary>
-    private TransitionState CylinderCollision(ShadowEntry obj, SpherePath sp)
+    private TransitionState CylinderCollision(ShadowEntry obj, SpherePath sp, PhysicsEngine engine)
     {
         var ci = CollisionInfo;
+        var oi = ObjectInfo;
         Vector3 sphereCurrPos = sp.GlobalCurrCenter[0].Origin;
         Vector3 sphereCheckPos = sp.GlobalSphere[0].Origin;
         float   sphRadius = sp.GlobalSphere[0].Radius;
@@ -2550,7 +2570,7 @@ public sealed class Transition
         if (distSqCheck >= combinedRSq)
             return TransitionState.OK;   // not overlapping at check position
 
-        // ─── Overlap detected: apply wall-slide ─────────────────────
+        // ─── Overlap detected ─────────────────────────────────────
         // Horizontal outward normal from the cylinder axis to the sphere
         // check position. For the degenerate case where the sphere center
         // is exactly on the axis, use the movement direction as a fallback
@@ -2571,6 +2591,46 @@ public sealed class Transition
             collisionNormal = new Vector3(dxCheck / distCheck, dyCheck / distCheck, 0f);
         }
 
+        // A6.P6 (2026-05-25): retail-faithful CCylSphere::step_sphere_up for
+        // Contact-grounded movers. acclient_2013_pseudo_c.txt:324516-324538.
+        //
+        // Retail check: step_up_height must clear (sphere.radius + cyl.height
+        // - offset.z) where offset.z is sphere center Z minus cyl low_pt Z.
+        // Geometrically: the height we need to lift the sphere to clear the
+        // cyl's top, less the sphere center's current height above the cyl
+        // base, equals cyl top minus sphere bottom (positive when sphere
+        // currently below cyl top).
+        //
+        // For the door's foot cyl (h=0.20m, sphere radius 0.48m, step_up 0.60m)
+        // at standing height (offset.z ~0.38m): cyl_clearance =
+        // 0.48 + 0.20 - 0.38 = 0.30m, step_up_height = 0.60m → step over OK.
+        if (oi.Contact && !sp.StepUp && !sp.StepDown && engine is not null)
+        {
+            float offsetZ = sphereCheckPos.Z - obj.Position.Z;
+            float cylClearance = sphRadius + cylTop - offsetZ;
+
+            if (oi.StepUpHeight >= cylClearance)
+            {
+                // Try step-up over the cyl (DoStepUp probes upward by
+                // step_up_height, then step-down for walkable surface).
+                // On success: sphere is repositioned past/over the cyl,
+                // ContactPlane updated, returns OK.
+                if (DoStepUp(collisionNormal, engine))
+                    return TransitionState.OK;
+
+                // Step-up failed — sphere couldn't find a walkable surface
+                // beyond the cyl (e.g., a wall behind it). Fall back to
+                // step_up_slide which uses the SlideSphereInternal crease
+                // projection — smoother than the radial push-out below
+                // because it follows the contact-plane / cyl-normal crease
+                // direction.
+                return sp.StepUpSlide(this);
+            }
+            // else: cyl too tall to step over — fall through to radial slide
+        }
+
+        // ─── Fallback: airborne / non-Contact / cyl-too-tall — wall-slide ───
+
         // Wall-slide position (in world space):
         //   curr = sphereCurrPos (pre-step)
         //   movement = sphMovement