diff --git a/src/AcDream.Core/Physics/BSPQuery.cs b/src/AcDream.Core/Physics/BSPQuery.cs
index cb32399..a6fb497 100644
--- a/src/AcDream.Core/Physics/BSPQuery.cs
+++ b/src/AcDream.Core/Physics/BSPQuery.cs
@@ -335,6 +335,12 @@ public static class BSPQuery
         CollisionSphere validPos,
         Vector3         movement)
     {
+        // A6.P1: snapshot inputs for the [push-back] probe (cheap copy of
+        // Vector3 + 2 floats). Only the LogPushBackAdjust call below pays
+        // the Console.WriteLine cost, and only when the probe is on.
+        var inputCenter = validPos.Center;
+        float walkInterpBefore = path.WalkInterp;
+
         float dpPos  = Vector3.Dot(validPos.Center, poly.Plane.Normal) + poly.Plane.D;
         float dpMove = Vector3.Dot(movement, poly.Plane.Normal);
         float dist;
@@ -342,7 +348,17 @@ public static class BSPQuery
         if (dpMove <= PhysicsGlobals.EPSILON)
         {
             if (dpMove >= -PhysicsGlobals.EPSILON)
+            {
+                if (PhysicsDiagnostics.ProbePushBackEnabled)
+                {
+                    PhysicsDiagnostics.LogPushBackAdjust(
+                        inputCenter, validPos.Center, poly.Plane, validPos.Radius,
+                        walkInterpBefore, path.WalkInterp,
+                        dpPos, dpMove, 0f,
+                        applied: false);
+                }
                 return false;
+            }
             dist = dpPos - validPos.Radius;
         }
         else
@@ -354,10 +370,30 @@ public static class BSPQuery
         float interp = (1f - iDist) * path.WalkInterp;
 
         if (interp >= path.WalkInterp || interp < -0.5f)
+        {
+            if (PhysicsDiagnostics.ProbePushBackEnabled)
+            {
+                PhysicsDiagnostics.LogPushBackAdjust(
+                    inputCenter, validPos.Center, poly.Plane, validPos.Radius,
+                    walkInterpBefore, path.WalkInterp,
+                    dpPos, dpMove, iDist,
+                    applied: false);
+            }
             return false;
+        }
 
         validPos.Center -= movement * iDist;
         path.WalkInterp  = interp;
+
+        if (PhysicsDiagnostics.ProbePushBackEnabled)
+        {
+            PhysicsDiagnostics.LogPushBackAdjust(
+                inputCenter, validPos.Center, poly.Plane, validPos.Radius,
+                walkInterpBefore, path.WalkInterp,
+                dpPos, dpMove, iDist,
+                applied: true);
+        }
+
         return true;
     }