diff --git a/game/reconstructed/mech4.cpp b/game/reconstructed/mech4.cpp
index e67da96..3e19ff4 100644
--- a/game/reconstructed/mech4.cpp
+++ b/game/reconstructed/mech4.cpp
@@ -1952,7 +1952,7 @@ void
 			// coupled root-motion experiment (BT_ROOT_POS=1) needs the MASTER-side
 			// gait mirror to stop the authority tug-of-war (measured ratio 1.86) --
 			// the completion path is mapped in the session notes.
-			static const int s_drPos = getenv("BT_ROOT_POS") ? 0 : 1;
+			static const int s_drPos = getenv("BT_DR_POS") ? 1 : 0;	// default 0 = authentic gait-coupled linear (BT_DR_POS=1 restores velocity)
 			Point3D replPrevPos = localOrigin.linearPosition;
 			Quaternion replPrevHeading = localOrigin.angularPosition;
 			DeadReckon(dt);							// engine reckoner: LINEAR position/velocity
@@ -3176,7 +3176,7 @@ void
 					// The master's VISIBLE motion uses the LEG channel reading live demand
 					// independently, so this does not change what the local player sees.
 					// (Default OFF: live overwrite preserved.)
-					static const int s_gaitMirror = getenv("BT_MASTER_GAITMIRROR") ? 1 : 0;
+					static const int s_gaitMirror = getenv("BT_NO_MASTER_GAITMIRROR") ? 0 : 1;	// default ON (authentic coupled)
 					if (s_gaitMirror)
 					{
 						/* leave bodyTargetSpeed at the last-sent value */
@@ -3744,7 +3744,7 @@ void
 			// velocity.  Re-seeded to localOrigin on each send by the record writers'
 			// projectedOrigin re-base, so this is incremental-from-last-send, exactly the
 			// peer's IntegrateMotion.  (Default OFF: constant-velocity deadReckoner.)
-			static const int s_gaitMirrorSend = getenv("BT_MASTER_GAITMIRROR") ? 1 : 0;
+			static const int s_gaitMirrorSend = getenv("BT_NO_MASTER_GAITMIRROR") ? 0 : 1;	// default ON
 			if (s_gaitMirrorSend)
 			{
 				Vector3D mAng;