diff --git a/game/reconstructed/mech.cpp b/game/reconstructed/mech.cpp
index c2e2519..69c8ce5 100644
--- a/game/reconstructed/mech.cpp
+++ b/game/reconstructed/mech.cpp
@@ -2118,6 +2118,9 @@ Mech::Mech(
 	ramLastVictim    = 0;								// ram contact-edge state
 	ramContactLinger = 0.0f;
 	lastInflictingDamage = 0.0f;						// task #60: killing-blow magnitude (set on hit)
+	mapPosture = 0;										// binary @0x3f8 (the ctor zero-block @0x4b3d18 zeroes the band)
+	myomerEffectiveness = 1.0f;							// binary @0x79c: 0-init + per-frame MAX; the port holds the
+														// healthy 1.0 until the Myomers Performance feeder lands [T3]
 	if (GroundReal() && GetCollisionVolumeCount() > 0
 		&& collisionTemplate != 0 && collisionVolume != 0)
 	{
diff --git a/game/reconstructed/mech.hpp b/game/reconstructed/mech.hpp
index 6544e3a..0260d23 100644
--- a/game/reconstructed/mech.hpp
+++ b/game/reconstructed/mech.hpp
@@ -1032,6 +1032,16 @@ protected:
 		Scalar			gimpStrideLength;		// @0x350
 		AlarmIndicator	legStateAlarm;			// @0x39c
 		int				legAnimationState;		// @0x3b0
+		int				mapPosture;				// binary @0x3f8 -- the map-legend/duck posture arbiter
+												//   (0 none / 1 may-duck / 2 holding-squat), computed per
+												//   master frame (FUN_004a9b5c @0x4a9f61-0x4aa007; the
+												//   CROUCH reconstruction, 2026-08-05)
+		Scalar			myomerEffectiveness;	// binary @0x79c -- init 0 then MAX over the heatable
+												//   chain's +0x31c each master frame; scales the mapper
+												//   speedDemand (dead myomers cripple the walk) and gates
+												//   the crouch.  FEEDER (Myomers Performance @004b8be3,
+												//   not in the export) UNRECONSTRUCTED -- the port holds
+												//   the healthy 1.0 [T3]; see the mech4 posture block.
 		Scalar			gimpSpeedMax;			// @0x52c
 		Scalar			standSpeed;				// @0x530
 		Scalar			walkStrideLength;		// @0x534
diff --git a/game/reconstructed/mech2.cpp b/game/reconstructed/mech2.cpp
index 2df2665..6323e5b 100644
--- a/game/reconstructed/mech2.cpp
+++ b/game/reconstructed/mech2.cpp
@@ -220,6 +220,16 @@ enum MechAnimationState
 void
 	Mech::SetLegAnimation(int state)
 {
+	// DIAG (BT_DUCK_LOG): every leg re-arm with the caller's return address --
+	// the crouch-clobber hunt (who re-arms after the squat parks?).
+	if (getenv("BT_DUCK_LOG"))
+	{
+		char dbuf[96];
+		sprintf(dbuf, "[duck] SetLegAnimation(%d) ra=btl4+0x%lx", state,
+			(unsigned long)_ReturnAddress()
+				- (unsigned long)GetModuleHandleA(0));
+		DEBUG_STREAM << dbuf << std::endl << std::flush;
+	}
 	legAnimation.SelectSequence(					// FUN_004277a8(this+0x65c, ...)
 		animationClips[state],						// *(this+0x5cc + state*4)
 		// The real leg finished-callback PTR_LAB_0050d6f0 == FUN_004a6928
diff --git a/game/reconstructed/mech4.cpp b/game/reconstructed/mech4.cpp
index 1726211..9fe16da 100644
--- a/game/reconstructed/mech4.cpp
+++ b/game/reconstructed/mech4.cpp
@@ -4348,6 +4348,95 @@ void
 		// and the Standing case returns adv=0 (no motion).  Only the LEGACY inline
 		// clip-select path (BT_GAIT_SM=0) still needs the throttle gate (it would
 		// loop the walk clip forever at idle).
+		//
+		// ---- MASTER POSTURE / CROUCH (raw disasm @0x4a9cf0-0x4aa0af, the dark
+		// master-perf region FUN_004a9b5c; decoded + reconstructed 2026-08-05).
+		// Binary order preserved: (1) the myomer factor -> speedDemand scale,
+		// (2) the posture selector (+0x3f8), (3) the DuckRequest consumer.
+		//
+		{
+			// (1) myomerEffectiveness (+0x79c): the binary inits 0 then MAXes
+			// the heatable chain's +0x31c (healthy myomers publish ~1.0;
+			// weapons park transient fireImpulse there) and multiplies the
+			// mapper's speedDemand -- dead muscles = a crawling mech.  The
+			// WRITER (Myomers Performance @004b8be3) is not in the export and
+			// stays unreconstructed, so the member holds the ctor's healthy
+			// 1.0 and this multiply is a live no-op until that dig lands
+			// (neutral-value deferral, the role=NULL pattern).  [T3 feeder]
+			{
+				MechControlsMapper *postureMppr = MappingMapper();
+				if (postureMppr != 0)
+					postureMppr->speedDemand *= myomerEffectiveness;
+			}
+
+			// (2) the posture selector (+0x3f8; feeds the map legend + the
+			// duck arbiter).  @0x4a9f61-0x4aa007: any non-zero movementMode
+			// -> 0; !simLive -> 0 (a NOVICE cannot crouch -- the same +0x25c
+			// lockout as the crit roll); leg alarm level 0/4 (standing /
+			// turn-in-place idle) -> myomers alive ? 1 : 0 (|factor| <= 1e-4
+			// == dead muscles, const @0x4ab16c); level 1 (parked in the
+			// squat) -> 2; anything else -> 0.
+			{
+				extern int BTPlayerExperienceSimLive(void *owner_mech);
+				const int postureLegLevel = (int)legStateAlarm.GetLevel();
+				// VALUE-SPACE NOTE: the binary tests +0x40 != 0 (its normal
+				// running state was 0); the task-#1 unification made our
+				// normal the engine ExistingState == 1 (bench: mode=1 while
+				// walking around).  Same intent -- "no special mode (limbo 2,
+				// airborne 3/4, dead 9, eject 10)".
+				const int postureMode = MovementMode();
+				if ((postureMode != 0 && postureMode != 1)
+					|| !BTPlayerExperienceSimLive((void *)this))
+					mapPosture = 0;
+				else if (postureLegLevel == 0 || postureLegLevel == 4)
+					mapPosture = (myomerEffectiveness <= 0.0001f
+						&& myomerEffectiveness >= -0.0001f) ? 0 : 1;
+				else if (postureLegLevel == 1)
+					mapPosture = 2;
+				else
+					mapPosture = 0;
+			}
+
+			// (3) the DuckRequest consumer (@0x4aa011-0x4aa0af), gated on the
+			// latched request AND squatCapable ('squ'/'sqd' clips shipped).
+			// Duck: SetLegAnimation(2) plays 'sqd'; LegClipFinished case-2
+			// parks the pose + sets leg alarm 1.  Rise: SetLegAnimation(3)
+			// plays 'squ'; case-3 restores alarm 0.  Both mark the type-3
+			// state record dirty (ForceUpdate 8 then 1 -- it ships legState +
+			// stability, so peers pose the squat for free) and flip the
+			// stability alarm (ducked = 0, risen = 1).  The request is
+			// consumed whenever both gates passed, hit or miss.
+			if (duckState != 0 && squatCapable != 0)
+			{
+				if (mapPosture == 1)
+				{
+					SetLegAnimation(2);					// 'sqd' -- squat down
+					ForceUpdate(8);
+					ForceUpdate(1);
+					stabilityAlarm.SetLevel(0);
+					if (getenv("BT_DUCK_LOG") || getenv("BT_GAIT_LOG"))
+						DEBUG_STREAM << "[duck] SQUAT (posture 1 -> leg clip 2)\n" << std::flush;
+				}
+				else if (mapPosture == 2)
+				{
+					SetLegAnimation(3);					// 'squ' -- rise
+					ForceUpdate(8);
+					ForceUpdate(1);
+					stabilityAlarm.SetLevel(1);
+					if (getenv("BT_DUCK_LOG") || getenv("BT_GAIT_LOG"))
+						DEBUG_STREAM << "[duck] RISE (posture 2 -> leg clip 3)\n" << std::flush;
+				}
+				else if (getenv("BT_DUCK_LOG"))
+					DEBUG_STREAM << "[duck] request consumed, posture=" << mapPosture
+						<< " (mode=" << MovementMode()
+						<< " legLvl=" << (int)legStateAlarm.GetLevel()
+						<< " simLive=" << 1	// re-read below costs a bridge call; posture already folded it
+						<< " myo=" << myomerEffectiveness
+						<< " squat=" << squatCapable << ")\n" << std::flush;
+				duckState = 0;							// consumed (@0x4aa0a9)
+			}
+		}
+
 		{
 			static const int s_gaitTicksAlways = BTEnvOn("BT_GAIT_SM", 1);
 			if (s_gaitTicksAlways || throttle != 0.0f)