myomer damage reaches the wheels, legs gimp at half structure, reverse refuses -- and an ODR trap unmasked (#75/#78)

The speed-demand site (MechControlsMapper::InterpretControls) now applies the
drive scale the mover's feed roster applied in 1995: speedDemand multiplies by
the myomers' live speedEffect (gear ratio, thermal curve, 1 - zone damage, via
the BTMyomersDriveOf bridge) and, while GIMPED, by 0.5 [T3: VGL Lynx's
"roughly 50%", BT_GIMP_SPEED overrides]. The gimp states were already being
raised -- mechdmg sets graphicAlarm 3 (left) / 4 (right) when a LegDamageZone-
flagged zone crosses half structure -- but nothing downstream ever saw them.
While gimped, reverse input is refused ("reverse disabled"), matching the
old-timers' account; the pod's audio cue rides the alarm's watchers.

Bench, one trajectory, arithmetically exact: a deterministic right-leg ramp
(the new BT_SELF_DAMAGE_ZONE harness) crosses 0.5 and the demand goes
44.837 -> 6.726 = 44.837 x 0.5 (gimp) x 0.3 (a crit-chewed myomers from the
same ramp -- the #80 crits composing with #75's scale, unprompted).

The reason "nothing downstream ever saw them" is the real find of the night,
now gotcha #23: AlarmIndicator is typedef'd to DIFFERENT TYPES per header
family -- mech.hpp says ReconAlarm (4 bytes), heat.hpp says GaugeAlarm (0x54)
-- so Mech::graphicAlarm and EVERY member after it sit at different offsets
depending on a TU's include order. mechdmg wrote level 4 and read it back;
mechmppr read 0 from the same object, same expression. No compiler error can
catch it: each TU only ever sees one definition. Until the split is audited,
cross-TU reads of the gimp level go through BTMechGimpLevel (compiled in
mechdmg's TU) -- and the same split-brain explains why the port carries the
binary's ONE movementMode cell as two live members (engine simulationState vs
graphicAlarm level) that never meet.

Also landed en route: the Myomers un-powered self-repair observed healing in
the field logs at exactly 0.011 x the authored Explosive scale per tick --
the 2026-07-29 reversal confirmed live; and Mech message 0x15 "RealMaxSpeed"
raw-decoded (@0x49f604: sets mech+0x7a0 from the message unless the +0x7a4
latch holds -- a console-tunable top speed).

Open on #78, documented in locomotion.md: the Gimp animation clips (authored
keys in the binary's model-record parser; mech2's state enum vs mech3's
reverse-fix disagree about slots 0x12-0x17 -- reconcile before wiring) and
the audio-cue binding.

Diags: BT_SELF_DAMAGE_ZONE, BT_DRIVE_LOG, BT_GIMP_SPEED.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

game/reconstructed/mech4.cpp

@@ -3791,6 +3791,10 @@ void
 					// the authentic MaxAcceleration reads directly since the task #4
 					// record-layout fix (madcat: 30 u/s^2); the old floor-25 block
 					// and its one-shot log are retired.
+					// (#78 note: the gimp states live on graphicAlarm, NOT this
+					// engine simulationState cell -- the port carries the
+					// binary's one mech+0x40 as two members; see the split-brain
+					// note in combat-damage.md.  This write never touches them.)
 					if (!IsMechDestroyed())						// a dead mech keeps its death movementMode
 						SetMovementMode(1);						// ground, non-death, non-airborne
 					// reverseSpeedMax2@0x7a0 is the run-cycle bodyCycleSpeed CLAMP (AdvanceBody
@@ -5614,10 +5618,21 @@ void
 				dmg.damageAmount = (want > 0.0f) ? want : 20.0f;
 				dmg.burstCount   = 1;
 				dmg.impactPoint  = localOrigin.linearPosition;
+				// BT_SELF_DAMAGE_ZONE=<n>: aim the harness at an explicit zone
+				// (#78 bench: ramp a LEG zone deterministically past the
+				// LegHalfStructure threshold).  Unset = -1 = the lottery.
+				int sdZone = -1;
+				{
+					const char *ze = getenv("BT_SELF_DAMAGE_ZONE");
+					if (ze != 0 && *ze != '\0')
+						sdZone = atoi(ze);
+					if (sdZone < -1 || sdZone >= damageZoneCount)
+						sdZone = -1;
+				}
 				Entity::TakeDamageMessage td(
 					Entity::TakeDamageMessageID,
 					sizeof(Entity::TakeDamageMessage),
-					GetEntityID(), -1 /*unaimed -> cylinder table resolves the zone*/, dmg);
+					GetEntityID(), sdZone /*-1 -> cylinder lottery*/, dmg);
 				DEBUG_STREAM << "[selfdmg] " << dmg.damageAmount
 					<< " to own mech (unaimed)" << std::endl << std::flush;
 				Dispatch(&td);