Camera seat LIVE + Mech::PlayerLinkMessageHandler reconstructed (@0049f624)

The spectator/broadcast seat works end-to-end: a hostType=1 +
vehicle=camera pilot page boots a CameraShip whose 62-camera arena1
network loads from the BTL4.RES type-27 resource (the engine's
CreateStreamedCameraInstances existed all along -- the file probe falls
back to it), the BTCameraDirector locks onto the first live mech, and
the ship TRACKS it (sees=1, goal advancing) and CUTS between authored
camera positions (screenshot-verified: wide arena shot -> close
tracking shot).

The missing piece was the Mech override of PlayerLinkMessageHandler
(@0049f624), which the reconstruction never filled.  The engine base
resolves mech->player; BT's override adds:
  1. the REVERSE link player->playerVehicle = this on EVERY node
     (replicants included) -- how the camera director and scoreboard
     find a REMOTE player's mech; without it a spectator parks forever
     ('NO goal entity')
  2. clears NonScoringPlayerFlag (0x4000 = bit 14): a pilot with a
     vehicle is a SCORING player -- this admits REPLICATED players to
     the ranking pass, so cross-node rank/score displays work
  3. master only: seeds the heat bank's ambientTemperature (bank
     @0x1d4) from the mission [mission] temperature= (BTMission+0xf4)
     -- correcting the heat family's 'frozen 300' deviation note (it
     was never frozen; THIS is the writer)

Bridge BTSetBankAmbientTemperature lives in heatfamily_reslice.cpp
(mech.cpp cannot include subsystem headers -- local-stub collision).
BT_CAM_LOG diagnostics: camera-network count, director pick + Players
group census, ship follow state, link dispatch/receive.

Verified live: 2-seat (mech + camera) relay session -- replicated
player shows +veh, director goal locked w/ 30s timer, ship tracking a
moving mech through camera cuts; standard 2-node mech smoke PASS
(un-regressed).  Lesson re-learned: a 'clean' build filtered on 'error
C' missed a linker file-lock failure -- one whole test cycle ran
against a stale exe (the /FORCE gotcha's cousin; grep -i error, not
error C).

Remaining (task open): ranking-window overlay draw (L4VIDRND stubs),
operator-app camera-seat row, shot polish.

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

game/reconstructed/mech.cpp

@@ -80,6 +80,12 @@
 // for the same reason.
 #include "dmgtable.hpp"
 extern Scalar BTGetTorsoTwist(Subsystem *torso);		// torso.cpp (Torso complete there)
+// heat-bank ambient bridge (heatfamily_reslice.cpp, AggregateHeatSink complete
+// there) -- mech.cpp cannot include the subsystem headers (local-stub collision)
+extern void BTSetBankAmbientTemperature(Subsystem *bank, Scalar temperature);
+#if !defined(BTMSSN_HPP)
+#	include <btmssn.hpp>		// BTMission::GetMissionTemperature (PlayerLink)
+#endif
 #if !defined(APP_HPP)
 #	include <app.hpp>
 #endif
@@ -454,6 +460,7 @@ const Receiver::HandlerEntry
 	Mech::MessageHandlerEntries[] =
 	{
 		MESSAGE_ENTRY(Mech, TakeDamage),
+		MESSAGE_ENTRY(Mech, PlayerLink),
 	};
 
 Receiver::MessageHandlerSet
@@ -609,6 +616,52 @@ Scalar
 	return tmpl ? tmpl->maxY : 0.0f;					// ResolveHit guards <= 0
 }
 
+//
+// Mech override of Entity::PlayerLinkMessageHandler (binary @0049f624).  The
+// engine base resolves the FORWARD link (mech->playerLink @0x190 from the
+// message's playerID); BT then:
+//   1. sets the REVERSE link player->playerVehicle = this -- on EVERY node,
+//      replicants included.  This is how the 1995 camera director
+//      (BeABTDirector's GetPlayerByIndex -> GetPlayerVehicle) and the
+//      scoreboard find a REMOTE player's mech; without it a spectator seat
+//      parks forever ("no goal entity", camera-seat bring-up 2026-07-18).
+//   2. clears the player's NonScoringPlayerFlag (0x4000 == bit 14): a pilot
+//      with a vehicle is a SCORING player -- this is what admits them to the
+//      ranking pass (Player::IsScoringPlayer gates RankPlayers).
+//   3. master only: seeds the heat bank's ambientTemperature (@0x1d4 on the
+//      0xBBE AggregateHeatSink at mech+0x7dc) from the mission's [mission]
+//      temperature (BTMission+0xf4) -- resolving the heat family's
+//      "frozen 300" deviation note: it was never frozen, THIS writes it.
+//
+void
+	Mech::PlayerLinkMessageHandler(PlayerLinkMessage *message)
+{
+	Check(message);
+	Entity::PlayerLinkMessageHandler(message);			// FUN_0041fd18: mech+0x190
+
+	Player *owner = GetPlayerLink();
+	if (getenv("BT_CAM_LOG"))
+		DEBUG_STREAM << "[cam] Mech::PlayerLink inst="
+			<< (int)(GetInstance() == ReplicantInstance)
+			<< " owner=" << (void*)owner << "\n" << std::flush;
+	if (owner != NULL)
+	{
+		owner->SetPlayerVehicle(this);					// player+0x1fc = this
+		owner->simulationFlags &= ~Player::NonScoringPlayerFlag;	// &= ~0x4000
+
+		if (GetInstance() != ReplicantInstance && sensorSubsystem != NULL)
+		{
+			Mission *mission = owner->GetMission();
+			if (mission != NULL)
+			{
+				BTSetBankAmbientTemperature(sensorSubsystem,
+					((BTMission *)mission)->GetMissionTemperature());
+			}
+		}
+	}
+	Check_Fpu();
+}
+
 //
 // Mech override of Entity::TakeDamageMessageHandler (binary @0x4a037a, the two
 // call sites into the glue @0x49ed0c).  An unaimed hit arrives with