#82 peers see a limping mech SKATING: the mech erased its own gimp cell every frame

The binary's one mech+0x40 IS Simulation::simulationState, which rides EVERY
update record header -- so in 1995 a peer's replicant learned the gimp level on
every packet and its gait limped with no gimp-specific replication anywhere.
The port's Mech::PerformAndWatch wrote SetMovementMode(1) every frame ("ground,
non-death, non-airborne"), which erased the level once it was mirrored in for
the warning voice (#78): the wire carried 1, bystanders walked while sliding at
limp speed, and the voice sequence restarted on every damage event (1->4 edge
per tick) instead of announcing once.

- mech4: that per-frame write now writes the AUTHORITATIVE level
  (gimped ? 3/4 : 1) via a new alarm-only bridge BTMechGimpAlarmLevel -- which
  deliberately never consults the cell it feeds, so a respawn-cleared alarm
  cannot re-latch stale gimp out of it.
- BTMechGimpLevel: falls back to the replicated cell, with ONE-CELL precedence
  (a fall/death/limbo state wins, so the normal drivers and their death latch
  run -- what the binary's single cell enforced structurally).
- Reverted the #78 record guard: on a replicant the master's records are
  authoritative, so pinning 3/4 against them would keep a peer limping through
  a respawn.  Fixed at the writer instead.
- [simstomp] trap now scoped to the watched mech with a module-relative return
  address (symcrash-able) -- that is what named the writer.
- Also learned + recorded: zone damage levels replicate only when the EXPLOSION
  TABLE's tier is crossed (peer measured at 0.428 vs master 0.857), so peer-side
  damage state must never be inferred from them.

Verified two-node (scratchpad/night6/mp_skate.sh): the observer's replicant gets
sim=4 and its gait runs 23 -> 25 (wgr entry -> ggl limp cycle).  Field clue that
cracked it: "after respawning a peer DID see the limp" (epilectrik/SAURON).
KB: locomotion.md + gotcha #25.

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

engine/MUNGA/SIMULATE.h

@@ -225,14 +225,19 @@ public:
 			{Check(this);
 			// #78 DIAG: trap the gimp-cell downgrade (3/4 -> <=1) with the
 			// caller's return address (symbolize via tools/symcrash.py).
-			if (getenv("BT_AUDIO_SPATIAL")) {
+			// #78/#82 DIAG: who resets the GIMP cell?  Scoped to the one mech
+			// mechdmg just gimped (g_btGimpWatchMech) -- subsystems are
+			// Simulations too and their 3->0 churn drowned the earlier trap.
+			// ra is printed MODULE-RELATIVE (btl4+0xNNNN) for symcrash.py.
+			{
+				extern void *g_btGimpWatchMech;
+				extern void BTGimpStompTrap(void *sim, unsigned cur,
+											unsigned nw, void *ra);
 				unsigned _cur = simulationState.GetState();
-				if ((_cur == 3 || _cur == 4) && new_state != _cur) {
-					static int s_ds=0; if (s_ds++<40)
-					DEBUG_STREAM << "[simstomp] " << _cur << "->" << new_state
-						<< " this=" << (void*)this
-						<< " ra=" << _ReturnAddress()
-						<< "\n" << std::flush; }
+				if ((void*)this == g_btGimpWatchMech
+					&& (_cur == 3 || _cur == 4) && new_state != _cur)
+					BTGimpStompTrap((void*)this, _cur, new_state,
+									_ReturnAddress());
 			}
 			simulationState.SetState(new_state);}