#110: cross-pod verified BOTH ways -- the cascade replicates, and peer fire alone drives it

Two two-node benches close the last stated gap ("no two-node run has watched a
peer's view of an arm death"), the second at the user's insistence on the REAL
field composition after the first used the self-damage scalpel:

1. mp_armchain.sh (scalpel): B self-destroys dz_rarm mid-fight.  A's screen
   receives the whole cascade -- [zone-repl] dz_rarm lvl 0->1 AND the cascaded
   dz_rgun lvl 0->1 -- plus the respawn reset coming back clean (1->0).  B's
   post-cascade AFC pushes turned out to be the RESPAWN RE-ARM, correct
   behavior, not a gate failure.  (Also confirmed: the self-damage harness
   dispatches a real Entity::TakeDamageMessage -- the identical path a peer's
   round takes, so the scalpel and the field share every line from the handler
   down.)

2. mp_armgrind.sh (the field composition): stand-off at 180, NO self-damage
   anywhere, A grinding B with real cross-pod fire for six minutes.  On B:
     * 25 incremental arm-zone hits from A's weapons via the cylinder tables
       (dz_rgun reached 1.0 from pure accumulation -- 15 cascades on rehits)
     * dz_rarm finished by B's OWN AFC bay cooking off (AmmoBinAFC100 BAY FIRE
       350, half into dz_rarm) -- itself lit by A's fire crits: peer-originated
       end to end
     * [cascade] zone 9 -> AFC100 + AmmoBinAFC100 + Condenser6 force-failed,
       fire gate refusals logged
   On A: [zone-repl] dz_rarm 0->1 and dz_rgun 0->1 -- the shooter SEES the arm
   and pod die.  B symmetrically received A's torso deaths.

Also: DamageZone::ReadUpdateRecord gets a change-only [zone-repl] diagnostic
(BT_MP_LOG) -- the probe that made the peer side measurable; mp_armgrind.sh
opens with the stale-node taskkill the other benches already had (a leftover
node from an aborted launch joined a later lobby as a third instance).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

engine/MUNGA/DAMAGE.cpp

@@ -160,6 +160,18 @@ void
 	Check_Pointer(update_record);
 	Verify(damageZoneIndex == update_record->damageZoneIndex);
 
+	// #110 MP verification (BT): log a PEER-side zone state transition, so the
+	// two-node bench can prove the destruction cascade replicates.  Change-only.
+	if (getenv("BT_MP_LOG")
+		&& (damageZoneGraphicState.GetState() != update_record->damageZoneGraphicState
+			|| (damageLevel < 1.0f && update_record->damageLevel >= 1.0f)))
+	{
+		DEBUG_STREAM << "[zone-repl] zone " << damageZoneIndex
+			<< " '" << (const char *)damageZoneName << "'"
+			<< " lvl " << damageLevel << "->" << update_record->damageLevel
+			<< " gstate " << damageZoneGraphicState.GetState()
+			<< "->" << update_record->damageZoneGraphicState << std::endl;
+	}
 	damageLevel = update_record->damageLevel;
 	damageZoneState.SetState(update_record->damageZoneState);
 	damageZoneGraphicState.SetState(update_record->damageZoneGraphicState);

scratchpad/night9/mp_armchain.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# #110 MP: node B's ARM ZONE dies (self-damage); what does PEER node A see?
+# PASS on A's log:
+#   [zone-repl] B's arm zone -> gstate 1, its child gun zone -> gstate 2 (Gone)
+#   B's arm-weapon salvo mirrors STOP after the cascade
+set -x
+. /c/git/bt411/scratchpad/night6/bench_common.sh
+cd /c/git/bt411/content || exit 1
+bt_assert_player_env
+rm -f mpc_a.log mpc_b.log
+bt_expert_egg MP.EGG MPC.EGG
+
+# node B: the victim -- self-destroys its right arm mid-fight
+BT_MP_LOG=1 BT_DMG_LOG=1 BT_DEATH_LOG=1 BT_PROJ_LOG=1 \
+BT_SELF_DAMAGE=4 BT_SELF_DAMAGE_ZONE=dz_rarm \
+BT_GOTO=enemy BT_GOTO_STOP=100 BT_AUTOFIRE=1 BT_AF_PERIOD=5 \
+  bt_launch mpc_b.log MPC.EGG 0x0C -net 1601
+sleep 2
+# node A: the observer
+BT_MP_LOG=1 BT_DMG_LOG=1 BT_PROJ_LOG=1 \
+BT_GOTO=enemy BT_GOTO_STOP=100 BT_AUTOFIRE=1 BT_AF_PERIOD=5 \
+  bt_launch mpc_a.log MPC.EGG 0x03 -net 1501
+sleep 5
+python ../tools/btconsole.py MPC.EGG 127.0.0.1:1501 127.0.0.1:1601 &
+PC=$!
+sleep 200
+kill $PC 2>/dev/null
+bt_kill_ours
+rm -f MPC.EGG
+echo DONE

scratchpad/night9/mp_armgrind.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+# #110 FIELD-COMPOSITION test: no self-damage anywhere.  A grinds B with real
+# cross-pod fire from a stand-off distance; the cylinder hit tables route a
+# share of every burst into B's arm wedges; when an arm zone crosses 1.0 the
+# cascade must fire ON B (sourced purely from A's damage), kill the arm's
+# weapons, and replicate to A ([zone-repl]).
+set -x
+. /c/git/bt411/scratchpad/night6/bench_common.sh
+cd /c/git/bt411/content || exit 1
+# stale nodes poison the lobby (a third instance joins the pair) -- clear first
+taskkill //F //IM btl4.exe > /dev/null 2>&1
+sleep 3
+bt_assert_player_env
+rm -f mpg_a.log mpg_b.log
+bt_expert_egg MP.EGG MPG.EGG
+
+# B: sparse return fire (observable weapons, loses the grind), stands its ground
+BT_MP_LOG=1 BT_DMG_LOG=1 BT_DEATH_LOG=1 BT_PROJ_LOG=1 \
+BT_GOTO=enemy BT_GOTO_STOP=180 BT_AUTOFIRE=1 BT_AF_PERIOD=9 \
+  bt_launch mpg_b.log MPG.EGG 0x0C -net 1601
+sleep 2
+# A: dense fire with missiles
+BT_MP_LOG=1 BT_DMG_LOG=1 BT_DEATH_LOG=1 BT_PROJ_LOG=1 \
+BT_GOTO=enemy BT_GOTO_STOP=180 BT_AUTOFIRE=1 BT_AF_MISSILE=1 BT_AF_PERIOD=3 \
+  bt_launch mpg_a.log MPG.EGG 0x03 -net 1501
+sleep 5
+python ../tools/btconsole.py MPG.EGG 127.0.0.1:1501 127.0.0.1:1601 &
+PC=$!
+sleep 360
+kill $PC 2>/dev/null
+bt_kill_ours
+rm -f MPG.EGG
+echo DONE