diff --git a/game/reconstructed/mech4.cpp b/game/reconstructed/mech4.cpp
index c6082d6..0061591 100644
--- a/game/reconstructed/mech4.cpp
+++ b/game/reconstructed/mech4.cpp
@@ -3591,17 +3591,62 @@ void
 				Scalar angDb = (updateTurnAngleDeadband    > 0.0f) ? updateTurnAngleDeadband    : -1.0f;
 				Scalar velDb = (updateTurnVelocityDeadband > 0.0f) ? updateTurnVelocityDeadband : -1.0f;
 				Logical resync = False;
+				int rzn = 0;	// 1=angleDrift 2=velDrift 4=cameToRestAng
+				// TRUE yaw drift in RADIANS (wrap-safe), to match the radian deadband
+				// angDb.  The prior `Abs(localOrigin.angularPosition.y -
+				// projectedOrigin.angularPosition.y)` compared raw QUATERNION y-components
+				// (sin(yaw/2)-ish, unitless) against a radian deadband -- both a units
+				// mismatch and wrap-unsafe: at the +-pi heading wrap the quaternion-y diff
+				// spikes toward its max (~2) and fired byAngle=56/56 EVERY frame (measured),
+				// flooding resyncs at every wrap.  Take the yaw difference in euler space
+				// and unwrap it to [-pi,pi] so a wrap is not seen as a ~2pi drift.
+				YawPitchRoll _yprL, _yprP;
+				_yprL = localOrigin.angularPosition;
+				_yprP = projectedOrigin.angularPosition;
+				Scalar _dyaw = (Scalar)(_yprL.yaw - _yprP.yaw);
+				while (_dyaw >  3.14159265f) _dyaw -= 6.28318531f;
+				while (_dyaw < -3.14159265f) _dyaw += 6.28318531f;
+				const Scalar angDrift = Abs(_dyaw);
+				// Compare the live yaw rate against the LAST-SENT rate (updateVelocity,
+				// which the type-4 writer copies straight from localVelocity, mech.cpp:2107)
+				// -- NOT projectedVelocity, which the master's dead-reckoner recomputes in a
+				// different representation/sign so the scalar-.y compare always read the full
+				// 2x mismatch and FLOODED a resync every frame (measured: byVel=55/55,
+				// velDrift=2.618=2x the 1.309 spin rate).  The flood reset the peer's
+				// dead-reckon horizon every frame, pinning its slerp at ~half rate -> the
+				// "rotates slow then jumps" spin.  updateVelocity is the value the peer
+				// actually extrapolates with, in the same units, so a steady spin now drifts
+				// 0 (no resync) and the peer extrapolates smoothly; a real rate change still
+				// diverges past velDb and fires.
+				// NB: the Abs() macro (STYLE.H:118) is UNPARENTHESIZED --
+				// Abs(a-b) mis-expands to (a-b>0 ? a-b : -a-b) == -(a+b) on the false
+				// branch, NOT |a-b|.  For a steady spin (localVy==updVy) that yields
+				// -(2*rate): on a reverse spin it is +2*rate and FLOODED a resync every
+				// frame (the confirmed root of the half-rate/freeze).  Diff into a temp and
+				// take an explicit abs so the macro only ever sees a single token.
+				const Scalar velDiff  = (Scalar)localVelocity.angularMotion.y - (Scalar)updateVelocity.angularMotion.y;
+				const Scalar velDrift = (velDiff < 0.0f) ? -velDiff : velDiff;
+				// ANGULAR SIGN hunt (BT_ANGSIGN, 0.2s): instantaneous gate values, to
+				// catch which of local/update/projected angular-Y carries the wrong sign.
+				if (getenv("BT_ANGSIGN"))
+				{
+					static float s_as = 0.0f; s_as += dt;
+					if (s_as >= 0.2f)
+					{
+						s_as = 0.0f;
+						DEBUG_STREAM << "[angsign] localVy=" << (Scalar)localVelocity.angularMotion.y
+							<< " updVy=" << (Scalar)updateVelocity.angularMotion.y
+							<< " projVy=" << (Scalar)projectedVelocity.angularMotion.y
+							<< " velDrift=" << velDrift << " angDrift=" << angDrift
+							<< " turn=" << turn << "\n" << std::flush;
+					}
+				}
 				if (angDb > 0.0f)
 				{
-					if (Abs(localOrigin.angularPosition.y
-							- projectedOrigin.angularPosition.y) > angDb)
-						resync = True;
-					if (Abs((Scalar)localVelocity.angularMotion.y
-							- (Scalar)projectedVelocity.angularMotion.y) > velDb)
-						resync = True;
+					if (angDrift > angDb) { resync = True; rzn |= 1; }
+					if (velDrift > velDb) { resync = True; rzn |= 2; }
 					if ((Scalar)localVelocity.angularMotion.y == 0.0f
-						&& (Scalar)updateVelocity.angularMotion.y != 0.0f)
-						resync = True;
+						&& (Scalar)updateVelocity.angularMotion.y != 0.0f) { resync = True; rzn |= 4; }
 				}
 				else if (Abs(angular_deviation.w) < 0.997f)
 				{
@@ -3611,6 +3656,27 @@ void
 				{
 					ForceUpdate(1 << MechResyncUpdateModelBit);	// type 4
 				}
+				// SPIN diagnosis (BT_SPIN, once/sec): how DENSE are the orientation
+				// (type-4) records while turning?  A stuttery peer spin == too sparse.
+				if (getenv("BT_SPIN"))
+				{
+					static float sAcc = 0.0f; static int sResync = 0, sFrames = 0, sAng = 0, sVel = 0, sRest = 0;
+					static float sMaxAng = 0.0f, sMaxVel = 0.0f;
+					sAcc += dt; sFrames++; if (resync) sResync++;
+					if (rzn & 1) sAng++; if (rzn & 2) sVel++; if (rzn & 4) sRest++;
+					if (angDrift > sMaxAng) sMaxAng = angDrift;
+					if (velDrift > sMaxVel) sMaxVel = velDrift;
+					if (sAcc >= 1.0f)
+					{
+						DEBUG_STREAM << "[spin-tx] resyncs=" << sResync << "/" << sFrames
+							<< " byAngle=" << sAng << " byVel=" << sVel << " byRest=" << sRest
+							<< " maxAng=" << sMaxAng << "(db" << angDb << ")"
+							<< " maxVel=" << sMaxVel << "(db" << velDb << ")"
+							<< " liveYaw=" << (Scalar)localVelocity.angularMotion.y
+							<< " updYaw=" << (Scalar)updateVelocity.angularMotion.y << "\n" << std::flush;
+						sAcc = 0.0f; sResync = 0; sFrames = 0; sAng = 0; sVel = 0; sRest = 0; sMaxAng = 0.0f; sMaxVel = 0.0f;
+					}
+				}
 			}
 			// Commanded-speed deadband (binary @0x4aac88): the mapper's live
 			// speedDemand vs the last-replicated bodyTargetSpeed -> the tiny