perf: harden runtime for weaker hardware

tests/simulation_scaling_benchmark_test.gd

@@ -3,6 +3,23 @@ extends SceneTree
 const SimulationManagerScript := preload("res://simulation/SimulationManager.gd")
 const BenchmarkScript := preload("res://simulation/benchmark/SimulationScalingBenchmark.gd")
 
+
+class CoverageDroppingManager:
+	extends "res://simulation/SimulationManager.gd"
+
+	var drop_after_simulation_ticks := -1
+	var simulation_ticks_seen := 0
+	var removed_combatant_id: StringName = &""
+
+	func simulate_tick() -> void:
+		super()
+		simulation_ticks_seen += 1
+		if simulation_ticks_seen != drop_after_simulation_ticks or npcs.is_empty():
+			return
+		removed_combatant_id = SimulationIds.npc_combatant_id(npcs[-1].id)
+		conflict_system.combatants.erase(removed_combatant_id)
+
+
 var failures: Array[String] = []
 
 
@@ -21,9 +38,22 @@ func _run() -> void:
 	_check(first["fixture_valid"], "The prepared benchmark state should pass schema validation")
 	_check(
 		(
-			int(first["schema_version"]) == SimulationScalingBenchmark.SCHEMA_VERSION
-			and StringName(first["workload_id"]) == SimulationScalingBenchmark.WORKLOAD_ID
+			int(first["schema_version"]) == 2
+			and SimulationScalingBenchmark.SCHEMA_VERSION == 2
+			and (
+				int(first["simulation_state_schema_version"])
+				== SimulationStateRecord.SCHEMA_VERSION
+			)
+			and StringName(first["workload_id"]) == &"full_fidelity_combatant_headless_arrival_v2"
+			and (
+				SimulationScalingBenchmark.WORKLOAD_ID
+				== &"full_fidelity_combatant_headless_arrival_v2"
+			)
 			and int(first["population"]) == 12
+			and int(first["npc_combatant_count"]) == 12
+			and bool(first["npc_combatant_coverage_valid"])
+			and int(first["fixture_npc_combatant_count"]) == 12
+			and bool(first["fixture_combatants_valid"])
 			and int(first["history_seed_events"]) == 24
 			and int(first["measured_ticks"]) == 8
 			and int(first["npc_updates"]) == 96
@@ -59,6 +89,8 @@ func _run() -> void:
 		"arrivals_processed",
 		"warmup_arrivals",
 		"tick_interval",
+		"npc_combatant_count",
+		"npc_combatant_coverage_valid",
 	]:
 		_check(
 			first[deterministic_key] == repeated[deterministic_key],
@@ -68,6 +100,14 @@ func _run() -> void:
 		first["final_checksum"] != different_seed["final_checksum"],
 		"A different fixture seed should produce a different deterministic checksum"
 	)
+	_check(
+		_coverage_loss_is_rejected(2, 3, 2),
+		"Coverage lost on the final warmup tick should reject the benchmark result"
+	)
+	_check(
+		_coverage_loss_is_rejected(2, 3, 5),
+		"Coverage lost on the final measured tick should reject the benchmark result"
+	)
 	_finish()
 
 
@@ -82,12 +122,57 @@ func _run_case(seed_value: int) -> Dictionary:
 		manager.free()
 		return {}
 	var fixture_valid := SimulationStateRecord.from_json(manager.serialize_state()) != null
+	var fixture_npc_combatant_count := 0
+	var fixture_combatants_valid := true
+	for npc in manager.npcs:
+		var combatant: CombatantStateRecord = manager.conflict_system.get_combatant(
+			SimulationIds.npc_combatant_id(npc.id)
+		)
+		if (
+			combatant == null
+			or combatant.get_npc_id() != npc.id
+			or combatant.get_display_name() != npc.npc_name
+			or not combatant.get_position().is_equal_approx(npc.position)
+		):
+			fixture_combatants_valid = false
+		else:
+			fixture_npc_combatant_count += 1
 	var result: Dictionary = benchmark.measure_manager(manager, 12, 24, 2, 8)
 	result["fixture_valid"] = fixture_valid
+	result["fixture_npc_combatant_count"] = fixture_npc_combatant_count
+	result["fixture_combatants_valid"] = fixture_combatants_valid
 	manager.free()
 	return result
 
 
+func _coverage_loss_is_rejected(
+	warmup_ticks: int, measured_ticks: int, drop_after_simulation_ticks: int
+) -> bool:
+	var manager := CoverageDroppingManager.new()
+	manager.simulation_seed = 9010
+	manager.debug_logs = false
+	manager.set_process(false)
+	root.add_child(manager)
+	var benchmark := BenchmarkScript.new()
+	var prepared := benchmark.prepare_manager(manager, 4, 0, manager.simulation_seed)
+	if not prepared:
+		manager.free()
+		return false
+	var target_id := SimulationIds.npc_combatant_id(manager.npcs[-1].id)
+	var target_existed := manager.conflict_system.get_combatant(target_id) != null
+	manager.drop_after_simulation_ticks = drop_after_simulation_ticks
+	var result: Dictionary = benchmark.measure_manager(manager, 4, 0, warmup_ticks, measured_ticks)
+	var rejected_after_exact_drop := (
+		target_existed
+		and manager.simulation_ticks_seen == drop_after_simulation_ticks
+		and manager.removed_combatant_id == target_id
+		and manager.conflict_system.get_combatant(target_id) == null
+		and result.is_empty()
+	)
+	manager.free()
+	return rejected_after_exact_drop
+
+
 func _check(condition: bool, message: String) -> void:
 	if not condition:
 		failures.append(message)