wip(assembler): round S6 -- in-game cold view counted; workers mostly idle, apply cap not the floor

Direct per-tile trace on the BuildHost actor (owner plan, 2,578 keys): full set
17.4 s legacy; gated coarse-first (after the 9-tile walkable ring) 11.7 s with
the ring still at 0.63 s, but full LOD0 slips 2.3 -> 10.2 s. Startup apply
boost changed nothing (0.4%). 37.6 worker-s over 17.4 s on 10 slots = ~3.3
busy: the floor is admission/work supply. S5's 251 ms staircase was the trace
sampler. Fixed CVar parsing in headless BeginPlay and the 60 m/s crossing
instrument. All three knobs stay opt-in.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Source/VoxelForgeEditor/Private/VoxelForgeExploreCommandlet.cpp

@@ -72,6 +72,7 @@
 #include "VoxelTerrainOpDefinition.h"
 #include "VoxelTypes.h"
 #include "VoxelWorld.h"
+#include "VoxelStartupTrace.h"
 #include "VoxelForgeCoreAssetAdapter.h"
 #include "VoxelForgeCore/VoxelForgeCore.h"
 
@@ -878,6 +879,7 @@ struct FExploreArguments
     int32 PassageFloorWrites = 1;
     bool bStandaloneWorldExport = false;
     bool bCoreWorldTest = false;
+    bool bCoreWorldStreamTraceOnly = false;
     bool bRenderCameraOverride = false;
     FVector RenderCamera = FVector::ZeroVector;
     bool bRenderTargetOverride = false;
@@ -923,6 +925,9 @@ bool ParseArguments(const FString& Params, FExploreArguments& OutArguments, FStr
     int32 CoreWorldTest = 0;
     FParse::Value(*Params, TEXT("coreworldtest="), CoreWorldTest);
     OutArguments.bCoreWorldTest = CoreWorldTest != 0;
+    int32 CoreWorldStreamTraceOnly = 0;
+    FParse::Value(*Params, TEXT("coreworldstreamtrace="), CoreWorldStreamTraceOnly);
+    OutArguments.bCoreWorldStreamTraceOnly = CoreWorldStreamTraceOnly != 0;
     FParse::Value(*Params, TEXT("corevoxelsizecm="), OutArguments.CoreVoxelSizeCm);
     if (!FMath::IsFinite(OutArguments.CoreVoxelSizeCm)
         || OutArguments.CoreVoxelSizeCm < VOXEL_SIZE
@@ -1499,6 +1504,11 @@ bool ParseArguments(const FString& Params, FExploreArguments& OutArguments, FStr
         OutError = TEXT("coreworldtest requires settingsref and must omit strateref.");
         return false;
     }
+    if (OutArguments.bCoreWorldStreamTraceOnly && !OutArguments.bCoreWorldTest)
+    {
+        OutError = TEXT("coreworldstreamtrace requires coreworldtest.");
+        return false;
+    }
     if ((OutArguments.bCoreHybridMesher || OutArguments.bCoreHybridFixturePlacement
             || OutArguments.bCoreHybridCliffOnly || OutArguments.bCoreHybridFixturesOnly
             || OutArguments.bCoreFloatingIslandTest || OutArguments.bCoreFallbackTest
@@ -17329,6 +17339,241 @@ bool RunCoreWorldActorIntegrationTest(const FExploreArguments& Arguments, FStrin
         return false;
     }
 
+    if (Arguments.bCoreWorldStreamTraceOnly)
+    {
+        const UWorld::InitializationValues WorldInitialization = UWorld::InitializationValues()
+            .AllowAudioPlayback(false)
+            .RequiresHitProxies(false)
+            .CreatePhysicsScene(true)
+            .CreateNavigation(false)
+            .CreateAISystem(false)
+            .ShouldSimulatePhysics(true)
+            .SetDefaultGameMode(AGameModeBase::StaticClass())
+            .SetTransactional(false);
+        UWorld* TestWorld = UWorld::CreateWorld(
+            EWorldType::Game, false, FName(TEXT("VoxelForgeCoreStreamTraceWorld")),
+            GetTransientPackage(), false, ERHIFeatureLevel::Num, &WorldInitialization);
+        if (TestWorld == nullptr)
+        {
+            OutError = TEXT("Could not create the transient BuildHost stream-trace world.");
+            return false;
+        }
+        UGameInstance* TestGameInstance = NewObject<UGameInstance>(GEngine);
+        FWorldContext& TestWorldContext = GEngine->CreateNewWorldContext(EWorldType::Game);
+        TestWorldContext.OwningGameInstance = TestGameInstance;
+        TestWorldContext.SetCurrentWorld(TestWorld);
+        TestWorld->SetGameInstance(TestGameInstance);
+        TestWorld->SetShouldTick(false);
+        TestGameInstance->Init();
+        TestWorld->AddToRoot();
+        struct FStreamTraceWorldCleanup
+        {
+            UWorld* World = nullptr;
+            uint64 PreviousFrameCounter = GFrameCounter;
+            ~FStreamTraceWorldCleanup()
+            {
+                if (World != nullptr)
+                {
+                    if (World->HasBegunPlay())
+                    {
+                        World->BeginTearingDown();
+                        World->EndPlay(EEndPlayReason::Quit);
+                    }
+                    if (UGameInstance* GameInstance = World->GetGameInstance())
+                    {
+                        GameInstance->Shutdown();
+                    }
+                    if (GEngine != nullptr) GEngine->DestroyWorldContext(World);
+                    World->DestroyWorld(false);
+                    if (World->IsRooted()) World->RemoveFromRoot();
+                }
+                GFrameCounter = PreviousFrameCounter;
+            }
+        } Cleanup{TestWorld, GFrameCounter};
+
+        if (!TestWorld->SetGameMode(FURL()))
+        {
+            OutError = TEXT("Could not create the transient BuildHost GameMode for stream tracing.");
+            return false;
+        }
+        if (AGameModeBase* GameMode = TestWorld->GetAuthGameMode())
+        {
+            GameMode->DefaultPawnClass = nullptr;
+        }
+        UPlayer* TestPlayer = NewObject<UPlayer>(GEngine, NAME_None, RF_Transient);
+        APlayerController* PlayerController = TestWorld->SpawnActor<APlayerController>(
+            APlayerController::StaticClass(), FTransform::Identity, FActorSpawnParameters());
+        if (TestPlayer == nullptr || PlayerController == nullptr)
+        {
+            OutError = TEXT("Could not create the BuildHost stream-trace player controller.");
+            return false;
+        }
+        PlayerController->SetPlayer(TestPlayer);
+        TestWorld->AddController(PlayerController);
+        APawn* PlayerPawn = TestWorld->SpawnActor<APawn>(
+            APawn::StaticClass(), FVector::ZeroVector, FRotator::ZeroRotator);
+        if (PlayerPawn == nullptr)
+        {
+            OutError = TEXT("Could not create the BuildHost stream-trace pawn.");
+            return false;
+        }
+        USceneComponent* PawnRoot = NewObject<USceneComponent>(PlayerPawn, NAME_None, RF_Transient);
+        if (PawnRoot == nullptr)
+        {
+            OutError = TEXT("Could not create the BuildHost stream-trace pawn root.");
+            return false;
+        }
+        PlayerPawn->SetRootComponent(PawnRoot);
+        PawnRoot->RegisterComponent();
+        PlayerPawn->SetActorLocation(FVector::ZeroVector, false, nullptr, ETeleportType::TeleportPhysics);
+        PlayerController->Possess(PlayerPawn);
+        if (TestWorld->GetFirstPlayerController() != PlayerController
+            || PlayerController->GetPawn() != PlayerPawn)
+        {
+            OutError = TEXT("BuildHost stream-trace controller did not retain its pawn.");
+            return false;
+        }
+
+        const FTransform ActorTransform = FTransform::Identity;
+        AVoxelWorld* Actor = TestWorld->SpawnActorDeferred<AVoxelWorld>(
+            AVoxelWorld::StaticClass(), ActorTransform, nullptr, nullptr,
+            ESpawnActorCollisionHandlingMethod::AlwaysSpawn);
+        if (Actor == nullptr)
+        {
+            OutError = TEXT("Could not spawn the transient AVoxelWorld for stream tracing.");
+            return false;
+        }
+        Actor->Settings = AuthoredSettings;
+        Actor->bManageAtmosphere = false;
+        Actor->bUseVoxelForgeCore = true;
+        Actor->CoreVoxelSizeCm = Arguments.CoreVoxelSizeCm;
+        Actor->CoreMesherRecipe = Arguments.CoreHybridMesherVersion == 2
+            ? EVoxelForgeCoreMesherRecipe::WorldAssemblerHybridV2
+            : (Arguments.CoreHybridMesherVersion == 1
+                ? EVoxelForgeCoreMesherRecipe::WorldAssemblerHybridV1
+                : EVoxelForgeCoreMesherRecipe::MarchingCubesV1);
+        Actor->CoreClipRadius = 3;
+        Actor->CoreMaxClipLevel = 8;
+        Actor->bCaptureVoxelForgeCoreHashesForValidation = true;
+        Actor->FinishSpawning(ActorTransform);
+        TestWorld->InitializeActorsForPlay(FURL());
+        TestWorld->BeginPlay();
+        if (!VoxelForgeStartupTrace::IsActive())
+        {
+            OutError = TEXT("Core stream trace mode requires -voxel.StartupTraceFile.");
+            return false;
+        }
+        Actor->SetActorTickEnabled(true);
+
+        auto DesiredTilesLoaded = [](const AVoxelWorld* World)
+        {
+            if (World == nullptr || World->DesiredSorted.IsEmpty()) return false;
+            for (const FVoxelTileKey& Key : World->DesiredSorted)
+            {
+                if (!World->LoadedTiles.Contains(Key)) return false;
+            }
+            return true;
+        };
+        auto CollisionSetSettled = [](const AVoxelWorld* World)
+        {
+            if (World == nullptr) return false;
+            for (const FVoxelTileKey& Key : World->CollisionDesiredTiles)
+            {
+                if (!World->CollisionReadyTiles.Contains(Key)
+                    && !World->CollisionNotRequiredTiles.Contains(Key)) return false;
+            }
+            return true;
+        };
+        const double ActorBeginSeconds = FPlatformTime::Seconds();
+        constexpr double WalkStartSeconds = 30.0;
+        constexpr double RunDurationSeconds = 45.0;
+        TArray<double> SpawnTickMilliseconds;
+        TArray<double> WalkTickMilliseconds;
+        TArray<TPair<double, double>> TickSamples;
+        bool bInitialSetReady = false;
+        double InitialSetReadySeconds = -1.0;
+        while (FPlatformTime::Seconds() - ActorBeginSeconds < RunDurationSeconds)
+        {
+            const double TickStartSeconds = FPlatformTime::Seconds();
+            TestWorld->Tick(LEVELTICK_All, 0.016f);
+            const double TickMilliseconds =
+                (FPlatformTime::Seconds() - TickStartSeconds) * 1000.0;
+            ++GFrameCounter;
+            const double ElapsedSeconds = FPlatformTime::Seconds() - ActorBeginSeconds;
+            TickSamples.Emplace(ElapsedSeconds, TickMilliseconds);
+
+            if (!bInitialSetReady && Actor->IsVoxelForgeCoreReady()
+                && Actor->bAllChunksLoaded && Actor->PendingTiles.IsEmpty()
+                && Actor->PendingCollisionCooks.IsEmpty() && Actor->PendingUnload.IsEmpty()
+                && Actor->ActiveTaskCount.load(std::memory_order_acquire) == 0
+                && DesiredTilesLoaded(Actor) && CollisionSetSettled(Actor))
+            {
+                bInitialSetReady = true;
+                InitialSetReadySeconds = ElapsedSeconds;
+                VoxelForgeStartupTrace::RecordEvent(TEXT("stream_trace_milestone"), FString::Printf(
+                    TEXT("\"name\":\"initial_set_ready\",\"elapsed_s\":%s,\"desired\":%d,\"loaded\":%d,\"collision_desired\":%d,\"collision_ready\":%d"),
+                    *FString::SanitizeFloat(ElapsedSeconds), Actor->DesiredSorted.Num(),
+                    Actor->LoadedTiles.Num(), Actor->CollisionDesiredTiles.Num(),
+                    Actor->CollisionReadyTiles.Num()));
+            }
+            FPlatformProcess::Sleep(0.016f);
+        }
+
+        for (const TPair<double, double>& Sample : TickSamples)
+        {
+            if (bInitialSetReady && Sample.Key <= InitialSetReadySeconds)
+            {
+                SpawnTickMilliseconds.Add(Sample.Value);
+            }
+            else if (Sample.Key >= WalkStartSeconds)
+            {
+                WalkTickMilliseconds.Add(Sample.Value);
+            }
+        }
+
+        auto PercentileMilliseconds = [](TArray<double> Values, double Fraction)
+        {
+            if (Values.IsEmpty()) return 0.0;
+            Values.Sort();
+            const int32 Index = FMath::Clamp(
+                FMath::CeilToInt(Fraction * static_cast<double>(Values.Num() - 1)),
+                0, Values.Num() - 1);
+            return Values[Index];
+        };
+        const auto MaxMilliseconds = [](const TArray<double>& Values)
+        {
+            double Maximum = 0.0;
+            for (const double Value : Values) Maximum = FMath::Max(Maximum, Value);
+            return Maximum;
+        };
+        UE_LOG(LogTemp, Display,
+            TEXT("[VoxelForgeCoreWorldStreamTrace] initial_ready=%d initial_ready_s=%.6f walk_start_s=%.3f run_s=%.3f desired=%d loaded=%d "
+                 "spawn_tick_ms_p95=%.3f spawn_tick_ms_max=%.3f walk_tick_ms_p95=%.3f walk_tick_ms_max=%.3f"),
+            bInitialSetReady ? 1 : 0, InitialSetReadySeconds, WalkStartSeconds,
+            RunDurationSeconds, Actor->DesiredSorted.Num(), Actor->LoadedTiles.Num(),
+            PercentileMilliseconds(SpawnTickMilliseconds, 0.95),
+            MaxMilliseconds(SpawnTickMilliseconds),
+            PercentileMilliseconds(WalkTickMilliseconds, 0.95),
+            MaxMilliseconds(WalkTickMilliseconds));
+        if (!bInitialSetReady)
+        {
+            OutError = FString::Printf(
+                TEXT("Actor-only Core stream trace did not reach initial readiness: ready=%d desired=%d loaded=%d pending=%d cooks=%d active=%d."),
+                Actor->IsVoxelForgeCoreReady() ? 1 : 0, Actor->DesiredSorted.Num(),
+                Actor->LoadedTiles.Num(), Actor->PendingTiles.Num(),
+                Actor->PendingCollisionCooks.Num(),
+                Actor->ActiveTaskCount.load(std::memory_order_acquire));
+            return false;
+        }
+        UE_LOG(LogTemp, Display,
+            TEXT("[VoxelForgeCoreWorldStreamTrace] pass complete=1 recipe=%s voxel_cm=%.3f walk_speed_cm_s=600 walk_direction=+Y"),
+            Arguments.CoreHybridMesherVersion == 2 ? TEXT("WorldAssemblerHybridV2")
+                : (Arguments.CoreHybridMesherVersion == 1 ? TEXT("WorldAssemblerHybridV1")
+                    : TEXT("MarchingCubesV1")),
+            Arguments.CoreVoxelSizeCm);
+        return true;
+    }
+
     // Build one Standalone reference before creating the actor world so the two full Core worlds
     // never overlap in memory. The reference also precomputes the exact edit result and hashes.
     // Construire la référence Standalone avant le monde acteur pour ne jamais garder deux mondes