#146 respawn: release the DESKTOP throttle -- and close #137, which was never a bug

#137 ("respawn came back with MYOMERS heat MAXED", Oracle; "overheating
generator D", Sauron) sent us through a full two-sided audit of Mech::Reset
and the whole RTIS chain.  Both sides were correct.  The answer was in the
field log all along, one line after the reset:

    [respawn] Mech::Reset 3:30 healed+moved to (...) alive=1
    [techstat] ... every live condition CLEARED
    [techstat] Myomers condition 3 SET        <- Overheating, immediately
    [mppr] in thr=1 -> ...
    [gaitSM] cycleSpeed=14.6 state=12         <- already RUNNING
    [techstat] Condenser5 condition 3 SET     <- "dumping into coolant loop 5"
    [techstat] GeneratorD condition 3 SET     <- Sauron's generator D

The mech respawns STILL UNDER POWER and earns the heat honestly.  Two facts
close it:

1. condition 3 is an OPERATING flag, not an alarm.  Census over one match:
   LLaser_2 33 SET / 33 CLEARED, LLaser_1 31/31, SRM4 26/26, PPC_2 18/18 --
   every volley trips it and clears it.  EVERY subsystem is balanced
   (GeneratorD 5/4, Myomers 5/4, Condenser5 1/1; the extra SET is only the
   log ending mid-heat).  cond 6 BadPower behaves the same (Myomers 8/8).
   Nothing latches.  A post-respawn SET is not evidence of anything.

2. Mech::Reset's subsystem loop starts at index 2 and the ControlsMapper is
   index 0, so the throttle is never reset -- and the BINARY does the same.
   That is right for a pod: the throttle is a PHYSICAL lever still under the
   pilot's hand.  Respawning under power is authentic and stays.

Oracle's read that the myomer heat rate "felt right" was correct.

WHAT IS a real defect (#146), desktop only: the glass bridge merely EMULATES
that lever, with the static ramp accumulator sLever (mech4.cpp:3250) zeroed
ONLY by the X all-stop and a direction-crossing snap.  A pad/keyboard pilot
is physically holding nothing and cannot see the lever, so they respawned at
speed for no reason they could perceive -- and ate the heat load above.  The
Thrustmaster/RIO path was never affected: InterpretControls (@004d2150)
rebuilds throttlePosition every frame from the databound throttleForward.

Fix: queue the existing all-stop at Mech::Reset, reusing the proven path
(it already clears the zero-crossing detent too).  LOCAL VIEWPOINT MECH ONLY
-- gBTDrive is the local bridge's state and Reset also runs for replicants,
so an ungated write would all-stop the player whenever a REMOTE mech
respawned.  Pod-safe besides: with a RIO present the key bridge is off and
gBTDrive.throttle is never read.  BT_NO_RESPAWN_THROTTLE_RELEASE=1 reverts.

Benched 2-node (scratchpad/night13/throttlerespawn.sh): the release fires
1:1 with local respawns on both nodes independently (A 2/2, B 1/1) and never
spuriously.  HONEST LIMIT: the viewpoint gate was NOT stressed -- B ran
Mech::Reset 0 times for A's mech, so the remote-respawn path never fired.
The gate is correct by construction (the isPlayerMech idiom), not proven.
BT_AUTODRIVE cannot test the lever itself (forced mode reads forcedThrottle,
never sLever), and the zeroing path is the X button, proven in the field.

Also keeps BTReportHeatAtReset (heat.cpp, BT_HEAT_LOG): the [heat-t] census
runs on a 5s timer, far too coarse to sample AT the reset.  It is what
proved every roster subsystem including all six Condensers sits at T=77
start=77, and it corrected an earlier false negative from filtering on
IsDerivedFrom(HeatSink).

KB: context/decomp-reference.md gains the routine/self-clearing condition
semantics + this post-mortem, so it is not re-chased; cross-ref in
context/gauges-hud.md.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018SgmXGNMXavXiafKXf9MDC

game/reconstructed/heat.cpp

@@ -1446,3 +1446,43 @@ int BTHeatSinkBankCoolantFraction(Subsystem *sub, Scalar *out)
 	*out = bank->CoolantFractionOf();
 	return 1;
 }
+
+//===========================================================================//
+// BTReportHeatAtReset -- #137 forensic (ungated when BT_HEAT_LOG is set).
+//
+// The [heat-t] census runs on a 5-second per-instance timer, which is far too
+// coarse to answer the question #137 actually poses: "respawn came back with
+// MYOMERS heat MAXED".  Is the temperature high BECAUSE the reset did not
+// clear it, or because it climbs again within the first second?  Those need a
+// sample taken AT the reset, which is what this is.  Called from Mech::Reset
+// immediately after the subsystem sweep, so every heat-bearing subsystem
+// reports the temperature the reset actually left it at.
+//===========================================================================//
+void BTReportHeatAtReset(void *mech_v)
+{
+	if (mech_v == 0 || getenv("BT_HEAT_LOG") == 0)
+		return;
+	Entity *mech = (Entity *)mech_v;
+	const int count = mech->GetSubsystemCount();
+	for (int i = 0; i < count; ++i)
+	{
+		Subsystem *s = mech->GetSubsystem(i);
+		if (s == 0)
+			continue;
+		// UNFILTERED first: the earlier pass filtered on IsDerivedFrom(HeatSink)
+		// and reported no Condensers.  That test rides a hand-built Derivation
+		// chain, so a false negative there is indistinguishable from "not in the
+		// roster" -- name every roster entry and say whether the test passed.
+		if (!s->IsDerivedFrom(*HeatableSubsystem::GetClassDerivations()))
+		{
+			DEBUG_STREAM << "[heat-reset] roster[" << i << "] "
+				<< (s->GetName() ? s->GetName() : "?")
+				<< "  (not HeatSink-derived)" << "\n" << std::flush;
+			continue;
+		}
+		HeatableSubsystem *sink = (HeatableSubsystem *)s;
+		DEBUG_STREAM << "[heat-reset] " << (s->GetName() ? s->GetName() : "?")
+			<< " T=" << (float)sink->currentTemperature
+						<< "\n" << std::flush;
+	}
+}