VoxelForge/Source/VoxelForgeEditor/Private/VoxelForgeExploreCommandlet.cpp

#include "VoxelForgeExploreCommandlet.h"
#include "VoxelStackOfflineSymbolizer.h"
#include "VoxelForgeRegionEvalExperiment.h"

#include "CoreMinimal.h"
#include "Async/ParallelFor.h"
#include "Commandlets/Commandlet.h"
#include "Containers/StringConv.h"
#include "HAL/FileManager.h"
#include "HAL/PlatformTime.h"
#include "HAL/PlatformTLS.h"
#include "IImageWrapper.h"
#include "IImageWrapperModule.h"
#include "Misc/CommandLine.h"
#include "Misc/FileHelper.h"
#include "Misc/Parse.h"
#include "Misc/Paths.h"
#include "Modules/ModuleManager.h"
#include "ProfilingDebugging/CpuProfilerTrace.h"
#include "Dom/JsonObject.h"
#include "Policies/CondensedJsonPrintPolicy.h"
#include "Serialization/Archive.h"
#include "Serialization/JsonReader.h"
#include "Serialization/JsonSerializer.h"
#include "Serialization/JsonWriter.h"
#include "UObject/Package.h"
#include "UObject/StrongObjectPtr.h"
#include "UObject/UObjectGlobals.h"
#include "VoxelCaveMorphology.h"
#include "VoxelDiffLayer.h"
#include "VoxelDensityOpStack.h"
#include "VoxelDensityAblation.h"
#include "VoxelDensityProfile.h"
#include "VoxelGenerator.h"
#include "VoxelGeometryHash.h"
#include "VoxelMarchingCubesMesher.h"
#include "VoxelNoise.h"
#include "VoxelPassageGeometry.h"
#include "VoxelSettings.h"
#include "VoxelStackSampler.h"
#include "VoxelStrateDefinition.h"
#include "VoxelStrateManager.h"
#include "VoxelStrateMeasure.h"
#include "VoxelStrateComposer.h"
#include "VoxelTypes.h"

#include <algorithm>
#include <atomic>
#include <limits>

namespace
{
using FExploreJsonWriter = TJsonWriter<TCHAR, TCondensedJsonPrintPolicy<TCHAR>>;

constexpr int32 DefaultRenderWidth = 512;
constexpr int32 DefaultRenderHeight = 288;
constexpr float DefaultRenderStepVoxels = 0.25f;
constexpr float DefaultRenderMaxDistanceVoxels = 160.0f;
constexpr int32 DefaultExportSize = 128;
constexpr int32 DefaultExportStep = 1;
constexpr int32 DefaultMaxWalkCells = 32000000;
constexpr float DefaultBudgetMinutes = 25.0f;
constexpr float MaxBudgetMinutes = 30.0f;
constexpr int32 MaxSyntheticStrates = 64;
constexpr int32 MaxRenderPixels = 1048576;
constexpr int64 MaxRenderDensitySamples = 400000000ll;
constexpr int32 MaxExportSize = 128;
constexpr int64 MaxWalkWorkingBytes = 768ll * 1024ll * 1024ll;
// The exact fine-grid walk retains Air + Density + player-fit bits + non-finite flags, and can
// transiently hold Parent + Queue + Path or Visited + NarrowCell + DFS stacks. 21 bytes/cell is a
// conservative preflight figure for those arrays, including allocator slack/headroom.
constexpr int64 EstimatedWalkBytesPerCell = 21ll;
constexpr int64 MaxExportWorkingBytes = 1024ll * 1024ll * 1024ll;

FString VoxelForgeSavedRoot()
{
    FString Root = FPaths::ConvertRelativePathToFull(
        FPaths::Combine(FPaths::ProjectDir(), TEXT("Plugins/VoxelForge/Saved")));
    FPaths::NormalizeDirectoryName(Root);
    return Root;
}

bool IsUnderVoxelForgeSaved(const FString& InPath)
{
    FString Candidate = FPaths::ConvertRelativePathToFull(InPath);
    FString Root = VoxelForgeSavedRoot();
    FPaths::NormalizeDirectoryName(Candidate);
    FPaths::NormalizeDirectoryName(Root);
    return Candidate.Equals(Root, ESearchCase::IgnoreCase)
        || Candidate.StartsWith(Root + TEXT("/"), ESearchCase::IgnoreCase)
        || Candidate.StartsWith(Root + TEXT("\\"), ESearchCase::IgnoreCase);
}

const TCHAR* ArchetypeName(ECaveGeneratorType Archetype)
{
    switch (Archetype)
    {
    case ECaveGeneratorType::TunnelNetwork:   return TEXT("TunnelNetwork");
    case ECaveGeneratorType::FlatPlain:       return TEXT("FlatPlain");
    case ECaveGeneratorType::CrystalChamber:  return TEXT("CrystalChamber");
    case ECaveGeneratorType::Maze:            return TEXT("Maze");
    case ECaveGeneratorType::SurfaceWorld:    return TEXT("SurfaceWorld");
    case ECaveGeneratorType::VerticalShafts:  return TEXT("VerticalShafts");
    case ECaveGeneratorType::FloatingIslands: return TEXT("FloatingIslands");
    case ECaveGeneratorType::Underwater:      return TEXT("Underwater");
    default:                                  return TEXT("Unknown");
    }
}

const TCHAR* ConnectivityResultName(EVoxelConnectivityResult Result)
{
    switch (Result)
    {
    case EVoxelConnectivityResult::Connected:                  return TEXT("Connected");
    case EVoxelConnectivityResult::NotConnectedAtThisResolution:
        return TEXT("NotConnectedAtThisResolution");
    case EVoxelConnectivityResult::StartCellSolid:             return TEXT("StartCellSolid");
    case EVoxelConnectivityResult::GoalCellSolid:              return TEXT("GoalCellSolid");
    case EVoxelConnectivityResult::OutOfWindow:                return TEXT("OutOfWindow");
    case EVoxelConnectivityResult::CoarseLiedBudgetExhausted:  return TEXT("CoarseLiedBudgetExhausted");
    case EVoxelConnectivityResult::StartCellNotPlayerFit:      return TEXT("StartCellNotPlayerFit");
    case EVoxelConnectivityResult::GoalCellNotPlayerFit:       return TEXT("GoalCellNotPlayerFit");
    default:                                                   return TEXT("Unknown");
    }
}

bool ParseArchetype(const FString& Text, ECaveGeneratorType& OutArchetype)
{
    FString Normalized = Text;
    Normalized.TrimStartAndEndInline();
    Normalized.ToLowerInline();
    Normalized.ReplaceInline(TEXT("_"), TEXT(""));
    Normalized.ReplaceInline(TEXT("-"), TEXT(""));

    const TPair<const TCHAR*, ECaveGeneratorType> Names[] = {
        { TEXT("tunnelnetwork"),   ECaveGeneratorType::TunnelNetwork },
        { TEXT("flatplain"),        ECaveGeneratorType::FlatPlain },
        { TEXT("crystalchamber"),   ECaveGeneratorType::CrystalChamber },
        { TEXT("maze"),             ECaveGeneratorType::Maze },
        { TEXT("surfaceworld"),     ECaveGeneratorType::SurfaceWorld },
        { TEXT("verticalshafts"),   ECaveGeneratorType::VerticalShafts },
        { TEXT("floatingislands"),  ECaveGeneratorType::FloatingIslands },
        { TEXT("floatingisland"),   ECaveGeneratorType::FloatingIslands },
        { TEXT("underwater"),       ECaveGeneratorType::Underwater },
    };
    for (const auto& Pair : Names)
    {
        if (Normalized == Pair.Key)
        {
            OutArchetype = Pair.Value;
            return true;
        }
    }
    return false;
}

const TCHAR* NoiseTypeName(EVoxelNoiseType NoiseType)
{
    switch (NoiseType)
    {
    case EVoxelNoiseType::FBM:      return TEXT("FBM");
    case EVoxelNoiseType::Ridged:   return TEXT("Ridged");
    case EVoxelNoiseType::Mixed:    return TEXT("Mixed");
    case EVoxelNoiseType::Cellular: return TEXT("Cellular");
    default:                        return TEXT("Unknown");
    }
}

bool ParseNoiseType(const FString& Text, EVoxelNoiseType& OutNoiseType)
{
    FString Normalized = Text;
    Normalized.TrimStartAndEndInline();
    Normalized.ToLowerInline();
    Normalized.ReplaceInline(TEXT("_"), TEXT(""));
    Normalized.ReplaceInline(TEXT("-"), TEXT(""));

    if (Normalized == TEXT("fbm") || Normalized == TEXT("fractal"))
    {
        OutNoiseType = EVoxelNoiseType::FBM;
        return true;
    }
    if (Normalized == TEXT("ridged") || Normalized == TEXT("ridge"))
    {
        OutNoiseType = EVoxelNoiseType::Ridged;
        return true;
    }
    if (Normalized == TEXT("mixed"))
    {
        OutNoiseType = EVoxelNoiseType::Mixed;
        return true;
    }
    if (Normalized == TEXT("cellular") || Normalized == TEXT("worley"))
    {
        OutNoiseType = EVoxelNoiseType::Cellular;
        return true;
    }
    return false;
}

bool ParseRenderCamera(const FString& Text, FVector& OutCamera)
{
    TArray<FString> Components;
    Text.ParseIntoArray(Components, TEXT(","), true);
    if (Components.Num() != 3)
    {
        return false;
    }

    const float X = FCString::Atof(*Components[0]);
    const float Y = FCString::Atof(*Components[1]);
    const float Z = FCString::Atof(*Components[2]);
    if (!FMath::IsFinite(X) || !FMath::IsFinite(Y) || !FMath::IsFinite(Z))
    {
        return false;
    }
    OutCamera = FVector(X, Y, Z);
    return true;
}

bool ParseDensitySlice(
    const FString& Text,
    FVector& OutOrigin,
    FVector& OutDirection,
    int32& OutSamples,
    float& OutStep)
{
    TArray<FString> Components;
    Text.ParseIntoArray(Components, TEXT(","), true);
    if (Components.Num() != 8)
    {
        return false;
    }

    const float OriginX = FCString::Atof(*Components[0]);
    const float OriginY = FCString::Atof(*Components[1]);
    const float OriginZ = FCString::Atof(*Components[2]);
    const float DirectionX = FCString::Atof(*Components[3]);
    const float DirectionY = FCString::Atof(*Components[4]);
    const float DirectionZ = FCString::Atof(*Components[5]);
    const int32 Samples = FCString::Atoi(*Components[6]);
    const float Step = FCString::Atof(*Components[7]);
    if (!FMath::IsFinite(OriginX) || !FMath::IsFinite(OriginY)
        || !FMath::IsFinite(OriginZ) || !FMath::IsFinite(DirectionX)
        || !FMath::IsFinite(DirectionY) || !FMath::IsFinite(DirectionZ)
        || !FMath::IsFinite(Step) || Samples < 2 || Samples > 4096
        || Step <= 0.0f)
    {
        return false;
    }

    FVector Direction(DirectionX, DirectionY, DirectionZ);
    if (!Direction.Normalize())
    {
        return false;
    }
    OutOrigin = FVector(OriginX, OriginY, OriginZ);
    OutDirection = Direction;
    OutSamples = Samples;
    OutStep = Step;
    return true;
}

bool NeedsOriginInWindow(ECaveGeneratorType Archetype)
{
    // This is the same topology policy as VoxelForgePlayerFitWindow.h. That header is test-only,
    // so the editor commandlet keeps the policy here while still delegating the actual fit test to
    // VoxelStrateMeasure's shared VF_ stencil.
    switch (Archetype)
    {
    case ECaveGeneratorType::Maze:
    case ECaveGeneratorType::VerticalShafts:
    case ECaveGeneratorType::TunnelNetwork:
    case ECaveGeneratorType::Underwater:
        return true;
    case ECaveGeneratorType::FlatPlain:
    case ECaveGeneratorType::CrystalChamber:
    case ECaveGeneratorType::SurfaceWorld:
    case ECaveGeneratorType::FloatingIslands:
    default:
        return false;
    }
}

float BoundarySealForArchetype(
    const UVoxelStrateDefinition& Definition,
    ECaveGeneratorType Archetype)
{
    switch (Archetype)
    {
    case ECaveGeneratorType::FlatPlain:
    case ECaveGeneratorType::CrystalChamber:
        return Definition.SlabParams.BoundarySealThickness;
    case ECaveGeneratorType::Maze:
        return Definition.MazeParams.BoundarySealThickness;
    case ECaveGeneratorType::SurfaceWorld:
        return Definition.SurfaceParams.BoundarySealThickness;
    case ECaveGeneratorType::VerticalShafts:
        return Definition.VerticalShaftParams.BoundarySealThickness;
    case ECaveGeneratorType::FloatingIslands:
        return Definition.FloatingIslandParams.BoundarySealThickness;
    case ECaveGeneratorType::TunnelNetwork:
    case ECaveGeneratorType::Underwater:
    default:
        return Definition.GenerationParams.BoundarySealThickness;
    }
}

struct FExploreArguments
{
    int32 Seed = 0;
    bool bSeedOverride = false;
    ECaveGeneratorType Archetype = ECaveGeneratorType::Maze;
    int32 Slot = 4;
    FString StrateReference;
    FString SettingsReference;
    bool bRender = true;
    bool bWalk = true;
    bool bExport = true;
    bool bWormsEnabledOverride = false;
    bool bWormsEnabled = true;
    bool bWormStrengthOverride = false;
    float WormStrength = 0.0f;
    bool bProfileDensity = false;
    bool bProfileDensityFull = false;
    bool bPerfAttribution = false;
    bool bSampleStacks = false;
    uint32 SampleStacksIntervalUs = FVoxelStackSampler::DefaultIntervalUs;
    bool bProfileLod = false;
    bool bOpBounds = false;
    bool bFailureFocusRender = false;
    FString OutDirectory;

    int32 RenderWidth = DefaultRenderWidth;
    int32 RenderHeight = DefaultRenderHeight;
    float RenderStepVoxels = DefaultRenderStepVoxels;
    float RenderMaxDistanceVoxels = DefaultRenderMaxDistanceVoxels;
    int32 ExportSize = DefaultExportSize;
    int32 ExportStep = DefaultExportStep;
    bool bExportTileOverride = false;
    int32 ExportTileX = 0;
    int32 ExportTileY = 0;
    int32 ExportTileZ = 0;
    // The canonical export owns one immutable lattice for the whole run.  Batch cases can pass
    // density_grid_reuse=false to produce a matched wall-clock control.
    bool bReuseDensityGrid = true;
    bool bBlockEarlyOut = false;
    // Opt-in parity mode: copy the runtime mesher presentation/LOD settings from the authored
    // settings object.  The default remains the historical bounded export configuration.
    bool bGameRuntimeConfig = false;
    int32 MeshMinBatchSize = 1;
    int32 MaxWalkCells = DefaultMaxWalkCells;
    float BudgetMinutes = DefaultBudgetMinutes;
    bool bSurfaceRoughnessOverride = false;
    float SurfaceRoughness = 0.0f;
    bool bTunnelWarpStrengthOverride = false;
    float TunnelWarpStrength = 0.0f;
    bool bRoughnessNoiseTypeOverride = false;
    EVoxelNoiseType RoughnessNoiseType = EVoxelNoiseType::FBM;
    bool bRoughnessFrequencyOverride = false;
    float RoughnessFrequency = 0.0f;
    bool bTunnelFloorEnabledOverride = false;
    int32 TunnelFloorEnabled = 1;
    bool bTunnelFloorTerracingOverride = false;
    int32 TunnelFloorTerracing = 1;
    bool bTunnelFloorStepOverride = false;
    float TunnelFloorStep = 0.0f;
    bool bTunnelFloorMaxLedgeOverride = false;
    float TunnelFloorMaxLedge = 0.0f;
    bool bTunnelFloorGentleOverride = false;
    float TunnelFloorGentle = 0.0f;
    bool bTunnelFloorLedgesOverride = false;
    int32 TunnelFloorLedges = 0;
    bool bTunnelFloorMaxLedgesOverride = false;
    int32 TunnelFloorMaxLedges = 0;
    bool bRoomMouthRiseOverride = false;
    float RoomMouthRise = 0.0f;
    bool bRoomMouthRiseBlendOverride = false;
    float RoomMouthRiseBlend = 0.0f;
    bool bPassageFloorWritesOverride = false;
    int32 PassageFloorWrites = 1;
    bool bRenderCameraOverride = false;
    FVector RenderCamera = FVector::ZeroVector;
    bool bRenderTargetOverride = false;
    FVector RenderTarget = FVector::ZeroVector;
    bool bDensitySlice = false;
    FVector DensitySliceOrigin = FVector::ZeroVector;
    FVector DensitySliceDirection = FVector::ForwardVector;
    int32 DensitySliceSamples = 257;
    float DensitySliceStep = 0.5f;
    bool bTunnelCoreProbe = false;

    bool IsDensityProfilingEnabled() const
    {
        return bProfileDensity || bPerfAttribution;
    }

    FString CanonicalModes() const
    {
        FString Result;
        if (bRender) Result += TEXT("render,");
        if (bWalk) Result += TEXT("walk,");
        if (bExport) Result += TEXT("export,");
        if (bOpBounds) Result += TEXT("opbounds,");
        if (bTunnelCoreProbe) Result += TEXT("tunnelcoreprobe,");
        if (Result.EndsWith(TEXT(",")))
        {
            Result.LeftChopInline(1);
        }
        return Result;
    }
};

bool ParseArguments(const FString& Params, FExploreArguments& OutArguments, FString& OutError)
{
    FString ArchetypeText = TEXT("Maze");
    FString ModesText = TEXT("render,walk,export");
    FString OutText;

    OutArguments.bSeedOverride = FParse::Value(*Params, TEXT("seed="), OutArguments.Seed);
    FParse::Value(*Params, TEXT("archetype="), ArchetypeText);
    FParse::Value(*Params, TEXT("slot="), OutArguments.Slot);
    FParse::Value(*Params, TEXT("strateref="), OutArguments.StrateReference);
    FParse::Value(*Params, TEXT("settingsref="), OutArguments.SettingsReference);
    FParse::Value(*Params, TEXT("modes="), ModesText);
    // FParse::Value treats a comma as a command-line separator in some UE commandlet
    // launch paths. Recover the complete token so both -modes=walk,export and the
    // quoted -modes="walk,export" form have the same meaning.
    const int32 ModesOffset = Params.Find(TEXT("modes="), ESearchCase::IgnoreCase);
    if (ModesOffset != INDEX_NONE)
    {
        ModesText = Params.Mid(ModesOffset + 6);
        const int32 ModesEnd = ModesText.Find(TEXT(" "));
        if (ModesEnd != INDEX_NONE)
        {
            ModesText.LeftInline(ModesEnd);
        }
        ModesText.TrimQuotesInline();
    }
    int32 WormsEnabled = 1;
    if (FParse::Value(*Params, TEXT("wormsenabled="), WormsEnabled))
    {
        OutArguments.bWormsEnabledOverride = true;
        OutArguments.bWormsEnabled = WormsEnabled != 0;
    }
    if (Params.Contains(TEXT("wormstrength="), ESearchCase::IgnoreCase)
        && FParse::Value(*Params, TEXT("wormstrength="), OutArguments.WormStrength))
    {
        OutArguments.bWormStrengthOverride = true;
    }
    OutArguments.bProfileDensity = FParse::Param(*Params, TEXT("profiledensity"));
    OutArguments.bProfileDensityFull = FParse::Param(*Params, TEXT("profiledensityfull"));
    OutArguments.bProfileDensity |= OutArguments.bProfileDensityFull;
    OutArguments.bPerfAttribution = FParse::Param(*Params, TEXT("perfattribution"));
    OutArguments.bSampleStacks = FParse::Param(*Params, TEXT("samplestacks"));
    int32 SampleStacksIntervalUs = static_cast<int32>(
        FVoxelStackSampler::DefaultIntervalUs);
    if (FParse::Value(*Params, TEXT("samplestacks="), SampleStacksIntervalUs))
    {
        OutArguments.bSampleStacks = true;
        OutArguments.SampleStacksIntervalUs = static_cast<uint32>(FMath::Max(0, SampleStacksIntervalUs));
    }
    OutArguments.bProfileLod = FParse::Param(*Params, TEXT("profilelod"));
    OutArguments.bOpBounds = FParse::Param(*Params, TEXT("opbounds"));
    OutArguments.bTunnelCoreProbe = FParse::Param(*Params, TEXT("tunnelcoreprobe"));
    FParse::Value(*Params, TEXT("out="), OutText);
    FParse::Value(*Params, TEXT("renderwidth="), OutArguments.RenderWidth);
    FParse::Value(*Params, TEXT("renderheight="), OutArguments.RenderHeight);
    FParse::Value(*Params, TEXT("renderstep="), OutArguments.RenderStepVoxels);
    FParse::Value(*Params, TEXT("rendermaxdistance="), OutArguments.RenderMaxDistanceVoxels);
    FParse::Value(*Params, TEXT("exportsize="), OutArguments.ExportSize);
    FParse::Value(*Params, TEXT("exportstep="), OutArguments.ExportStep);
    const bool bExportTileXSpecified = Params.Contains(
        TEXT("exporttilex="), ESearchCase::IgnoreCase);
    const bool bExportTileYSpecified = Params.Contains(
        TEXT("exporttiley="), ESearchCase::IgnoreCase);
    const bool bExportTileZSpecified = Params.Contains(
        TEXT("exporttilez="), ESearchCase::IgnoreCase);
    if (bExportTileXSpecified || bExportTileYSpecified || bExportTileZSpecified)
    {
        if (!bExportTileXSpecified || !bExportTileYSpecified || !bExportTileZSpecified
            || !FParse::Value(*Params, TEXT("exporttilex="), OutArguments.ExportTileX)
            || !FParse::Value(*Params, TEXT("exporttiley="), OutArguments.ExportTileY)
            || !FParse::Value(*Params, TEXT("exporttilez="), OutArguments.ExportTileZ))
        {
            OutError = TEXT("exporttilex, exporttiley, and exporttilez must be supplied together as level-0 tile coordinates.");
            return false;
        }
        OutArguments.bExportTileOverride = true;
    }
    int32 DensityGridReuse = OutArguments.bReuseDensityGrid ? 1 : 0;
    FParse::Value(*Params, TEXT("densitygridreuse="), DensityGridReuse);
    OutArguments.bReuseDensityGrid = DensityGridReuse != 0;
    int32 BlockEarlyOut = OutArguments.bBlockEarlyOut ? 1 : 0;
    FParse::Value(*Params, TEXT("blockearlyout="), BlockEarlyOut);
    OutArguments.bBlockEarlyOut = BlockEarlyOut != 0;
    int32 GameRuntimeConfig = OutArguments.bGameRuntimeConfig ? 1 : 0;
    FParse::Value(*Params, TEXT("gameconfig="), GameRuntimeConfig);
    FParse::Value(*Params, TEXT("paritygame="), GameRuntimeConfig);
    OutArguments.bGameRuntimeConfig = GameRuntimeConfig != 0;
    FParse::Value(*Params, TEXT("meshminbatch="), OutArguments.MeshMinBatchSize);
    OutArguments.MeshMinBatchSize = FMath::Clamp(OutArguments.MeshMinBatchSize, 1, 64);
    int32 Lod = 0;
    if (FParse::Value(*Params, TEXT("lod="), Lod))
    {
        if (Lod < 0 || Lod > 3)
        {
            OutError = TEXT("lod must be an integer in [0,3].");
            return false;
        }
        OutArguments.ExportStep = 1 << Lod;
    }
    FParse::Value(*Params, TEXT("maxwalkcells="), OutArguments.MaxWalkCells);
    FParse::Value(*Params, TEXT("budget="), OutArguments.BudgetMinutes);
    const bool bSurfaceRoughnessSpecified = Params.Contains(
        TEXT("surfaceroughness="), ESearchCase::IgnoreCase);
    const bool bSurfaceRoughnessParsed = FParse::Value(
        *Params, TEXT("surfaceroughness="), OutArguments.SurfaceRoughness);
    OutArguments.bSurfaceRoughnessOverride = bSurfaceRoughnessSpecified;
    const bool bTunnelWarpStrengthSpecified = Params.Contains(
        TEXT("tunnelwarp="), ESearchCase::IgnoreCase);
    const bool bTunnelWarpStrengthParsed = FParse::Value(
        *Params, TEXT("tunnelwarp="), OutArguments.TunnelWarpStrength);
    OutArguments.bTunnelWarpStrengthOverride = bTunnelWarpStrengthSpecified;
    FString RoughnessNoiseTypeText;
    const bool bRoughnessNoiseTypeSpecified = Params.Contains(
        TEXT("roughnesstype="), ESearchCase::IgnoreCase);
    const bool bRoughnessNoiseTypeParsed = FParse::Value(
        *Params, TEXT("roughnesstype="), RoughnessNoiseTypeText)
        && ParseNoiseType(RoughnessNoiseTypeText, OutArguments.RoughnessNoiseType);
    OutArguments.bRoughnessNoiseTypeOverride = bRoughnessNoiseTypeSpecified;
    const bool bRoughnessFrequencySpecified = Params.Contains(
        TEXT("roughnessfrequency="), ESearchCase::IgnoreCase);
    const bool bRoughnessFrequencyParsed = FParse::Value(
        *Params, TEXT("roughnessfrequency="), OutArguments.RoughnessFrequency);
    OutArguments.bRoughnessFrequencyOverride = bRoughnessFrequencySpecified;
    const bool bTunnelFloorEnabledSpecified = Params.Contains(
        TEXT("tunnelfloor="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorEnabledParsed = FParse::Value(
        *Params, TEXT("tunnelfloor="), OutArguments.TunnelFloorEnabled);
    OutArguments.bTunnelFloorEnabledOverride = bTunnelFloorEnabledSpecified;
    const bool bTunnelFloorTerracingSpecified = Params.Contains(
        TEXT("tunnelfloorterracing="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorTerracingParsed = FParse::Value(
        *Params, TEXT("tunnelfloorterracing="), OutArguments.TunnelFloorTerracing);
    OutArguments.bTunnelFloorTerracingOverride = bTunnelFloorTerracingSpecified;
    const bool bTunnelFloorStepSpecified = Params.Contains(
        TEXT("tunnelfloorstep="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorStepParsed = FParse::Value(
        *Params, TEXT("tunnelfloorstep="), OutArguments.TunnelFloorStep);
    OutArguments.bTunnelFloorStepOverride = bTunnelFloorStepSpecified;
    const bool bTunnelFloorMaxLedgeSpecified = Params.Contains(
        TEXT("tunnelfloormaxledge="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorMaxLedgeParsed = FParse::Value(
        *Params, TEXT("tunnelfloormaxledge="), OutArguments.TunnelFloorMaxLedge);
    OutArguments.bTunnelFloorMaxLedgeOverride = bTunnelFloorMaxLedgeSpecified;
    const bool bTunnelFloorGentleSpecified = Params.Contains(
        TEXT("tunnelfloorgentle="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorGentleParsed = FParse::Value(
        *Params, TEXT("tunnelfloorgentle="), OutArguments.TunnelFloorGentle);
    OutArguments.bTunnelFloorGentleOverride = bTunnelFloorGentleSpecified;
    const bool bTunnelFloorLedgesSpecified = Params.Contains(
        TEXT("tunnelfloorledges="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorLedgesParsed = FParse::Value(
        *Params, TEXT("tunnelfloorledges="), OutArguments.TunnelFloorLedges);
    OutArguments.bTunnelFloorLedgesOverride = bTunnelFloorLedgesSpecified;
    const bool bTunnelFloorMaxLedgesSpecified = Params.Contains(
        TEXT("tunnelfloormaxledges="), ESearchCase::IgnoreCase);
    const bool bTunnelFloorMaxLedgesParsed = FParse::Value(
        *Params, TEXT("tunnelfloormaxledges="), OutArguments.TunnelFloorMaxLedges);
    OutArguments.bTunnelFloorMaxLedgesOverride = bTunnelFloorMaxLedgesSpecified;
    const bool bRoomMouthRiseSpecified = Params.Contains(
        TEXT("roommouthrise="), ESearchCase::IgnoreCase);
    const bool bRoomMouthRiseParsed = FParse::Value(
        *Params, TEXT("roommouthrise="), OutArguments.RoomMouthRise);
    OutArguments.bRoomMouthRiseOverride = bRoomMouthRiseSpecified;
    const bool bRoomMouthRiseBlendSpecified = Params.Contains(
        TEXT("roommouthriseblend="), ESearchCase::IgnoreCase);
    const bool bRoomMouthRiseBlendParsed = FParse::Value(
        *Params, TEXT("roommouthriseblend="), OutArguments.RoomMouthRiseBlend);
    OutArguments.bRoomMouthRiseBlendOverride = bRoomMouthRiseBlendSpecified;
    const bool bPassageFloorWritesSpecified = Params.Contains(
        TEXT("passagefloorwrites="), ESearchCase::IgnoreCase);
    const bool bPassageFloorWritesParsed = FParse::Value(
        *Params, TEXT("passagefloorwrites="), OutArguments.PassageFloorWrites);
    OutArguments.bPassageFloorWritesOverride = bPassageFloorWritesSpecified;

    FString RenderCameraText;
    const bool bRenderCameraSpecified = Params.Contains(
        TEXT("rendercamera="), ESearchCase::IgnoreCase);
    bool bRenderCameraParsed = false;
    if (bRenderCameraSpecified)
    {
        const int32 CameraOffset = Params.Find(TEXT("rendercamera="), ESearchCase::IgnoreCase);
        if (CameraOffset != INDEX_NONE)
        {
            RenderCameraText = Params.Mid(CameraOffset + 13);
            const int32 CameraEnd = RenderCameraText.Find(TEXT(" "));
            if (CameraEnd != INDEX_NONE)
            {
                RenderCameraText.LeftInline(CameraEnd);
            }
            RenderCameraText.TrimQuotesInline();
            bRenderCameraParsed = ParseRenderCamera(RenderCameraText, OutArguments.RenderCamera);
        }
    }
    OutArguments.bRenderCameraOverride = bRenderCameraSpecified;

    FString RenderTargetText;
    const bool bRenderTargetSpecified = Params.Contains(
        TEXT("rendertarget="), ESearchCase::IgnoreCase);
    bool bRenderTargetParsed = false;
    if (bRenderTargetSpecified)
    {
        const int32 TargetOffset = Params.Find(TEXT("rendertarget="), ESearchCase::IgnoreCase);
        if (TargetOffset != INDEX_NONE)
        {
            RenderTargetText = Params.Mid(TargetOffset + 13);
            const int32 TargetEnd = RenderTargetText.Find(TEXT(" "));
            if (TargetEnd != INDEX_NONE)
            {
                RenderTargetText.LeftInline(TargetEnd);
            }
            RenderTargetText.TrimQuotesInline();
            bRenderTargetParsed = ParseRenderCamera(RenderTargetText, OutArguments.RenderTarget);
        }
    }
    OutArguments.bRenderTargetOverride = bRenderTargetSpecified;

    FString DensitySliceText;
    const bool bDensitySliceSpecified = Params.Contains(
        TEXT("densityslice="), ESearchCase::IgnoreCase);
    bool bDensitySliceParsed = false;
    if (bDensitySliceSpecified)
    {
        const int32 SliceOffset = Params.Find(TEXT("densityslice="), ESearchCase::IgnoreCase);
        if (SliceOffset != INDEX_NONE)
        {
            DensitySliceText = Params.Mid(SliceOffset + 13);
            const int32 SliceEnd = DensitySliceText.Find(TEXT(" "));
            if (SliceEnd != INDEX_NONE)
            {
                DensitySliceText.LeftInline(SliceEnd);
            }
            DensitySliceText.TrimQuotesInline();
            bDensitySliceParsed = ParseDensitySlice(
                DensitySliceText,
                OutArguments.DensitySliceOrigin,
                OutArguments.DensitySliceDirection,
                OutArguments.DensitySliceSamples,
                OutArguments.DensitySliceStep);
        }
    }
    OutArguments.bDensitySlice = bDensitySliceSpecified;
    int32 FailureFocusRender = 0;
    FParse::Value(*Params, TEXT("failurefocus="), FailureFocusRender);
    OutArguments.bFailureFocusRender = FailureFocusRender != 0;

    if (!ParseArchetype(ArchetypeText, OutArguments.Archetype))
    {
        OutError = FString::Printf(
            TEXT("Unknown archetype '%s'. Expected Maze, TunnelNetwork, FlatPlain, "
                 "CrystalChamber, SurfaceWorld, VerticalShafts, FloatingIslands, or Underwater."),
            *ArchetypeText);
        return false;
    }

    OutArguments.bRender = false;
    OutArguments.bWalk = false;
    OutArguments.bExport = false;
    TArray<FString> Modes;
    ModesText.ParseIntoArray(Modes, TEXT(","), true);
    for (FString Mode : Modes)
    {
        Mode.TrimStartAndEndInline();
        Mode.ToLowerInline();
        if (Mode == TEXT("all"))
        {
            OutArguments.bRender = true;
            OutArguments.bWalk = true;
            OutArguments.bExport = true;
        }
        else if (Mode == TEXT("opbounds"))
        {
            OutArguments.bOpBounds = true;
        }
        else if (Mode == TEXT("tunnelcoreprobe"))
        {
            OutArguments.bTunnelCoreProbe = true;
        }
        else if (Mode == TEXT("render"))
        {
            OutArguments.bRender = true;
        }
        else if (Mode == TEXT("walk"))
        {
            OutArguments.bWalk = true;
        }
        else if (Mode == TEXT("export"))
        {
            OutArguments.bExport = true;
        }
        else
        {
            OutError = FString::Printf(
                TEXT("Unknown mode '%s'. Expected render, walk, export, opbounds, tunnelcoreprobe, or all."), *Mode);
            return false;
        }
    }
    if (!OutArguments.bRender && !OutArguments.bWalk && !OutArguments.bExport
        && !OutArguments.bOpBounds && !OutArguments.bTunnelCoreProbe)
    {
        OutError = TEXT("At least one mode must be selected.");
        return false;
    }

    // The historical explorer contract needs two adjacent mouths around an interior slot.  A
    // parity export can instead target the game's authored single-strate layout, which has no
    // such mouths and is valid for export-only mode.  Build() still validates the slot against
    // the loaded settings layout.
    const int32 MinimumSlot = OutArguments.bGameRuntimeConfig ? 0 : 1;
    const int32 MaximumSlot = OutArguments.bGameRuntimeConfig
        ? MaxSyntheticStrates - 1 : MaxSyntheticStrates - 2;
    if (OutArguments.Slot < MinimumSlot || OutArguments.Slot > MaximumSlot)
    {
        if (OutArguments.bGameRuntimeConfig)
        {
            OutError = FString::Printf(
                TEXT("slot must be in [0,%d] for game-runtime configuration parity."),
                MaxSyntheticStrates - 1);
        }
        else
        {
            OutError = FString::Printf(
                TEXT("slot must be an interior slot in [1,%d] so arrival and departure mouths exist."),
                MaxSyntheticStrates - 2);
        }
        return false;
    }
    if (OutArguments.RenderWidth < 16 || OutArguments.RenderHeight < 16
        || static_cast<int64>(OutArguments.RenderWidth)
            * static_cast<int64>(OutArguments.RenderHeight) > MaxRenderPixels)
    {
        OutError = FString::Printf(
            TEXT("renderwidth*renderheight must be between 256 pixels and %d pixels."),
            MaxRenderPixels);
        return false;
    }
    if (!FMath::IsFinite(OutArguments.RenderStepVoxels)
        || OutArguments.RenderStepVoxels < 0.125f
        || OutArguments.RenderStepVoxels > 8.0f)
    {
        OutError = TEXT("renderstep must be finite and in [0.125,8] voxels.");
        return false;
    }
    if (!FMath::IsFinite(OutArguments.RenderMaxDistanceVoxels)
        || OutArguments.RenderMaxDistanceVoxels <= 0.0f
        || OutArguments.RenderMaxDistanceVoxels > 2048.0f)
    {
        OutError = TEXT("rendermaxdistance must be finite and in (0,2048] voxels.");
        return false;
    }
    // Render does not budget density samples: pixels are rasterised from the one canonical
    // mesh. Keep the legacy renderstep/maxdistance arguments for compatible invocations and use
    // only maxdistance as the raster depth clip.
    if (OutArguments.ExportSize < CHUNK_SIZE
        || OutArguments.ExportSize > MaxExportSize
        || OutArguments.ExportSize % CHUNK_SIZE != 0)
    {
        OutError = FString::Printf(
            TEXT("exportsize must be a multiple of CHUNK_SIZE (%d) in [%d,%d] cells per axis."),
            CHUNK_SIZE,
            CHUNK_SIZE,
            MaxExportSize);
        return false;
    }
    if (OutArguments.ExportStep < 1
        || OutArguments.ExportStep > 8
        || (OutArguments.ExportStep & (OutArguments.ExportStep - 1)) != 0
        || CHUNK_SIZE % OutArguments.ExportStep != 0)
    {
        OutError = TEXT("exportstep must be a power of two in [1,8] and divide CHUNK_SIZE.");
        return false;
    }
    if (OutArguments.MaxWalkCells <= 0)
    {
        OutError = TEXT("maxwalkcells must be greater than zero.");
        return false;
    }
    if (!FMath::IsFinite(OutArguments.BudgetMinutes)
        || OutArguments.BudgetMinutes <= 0.0f
        || OutArguments.BudgetMinutes > MaxBudgetMinutes)
    {
        OutError = FString::Printf(
            TEXT("budget must be finite and in (0,%g] minutes."), MaxBudgetMinutes);
        return false;
    }
    if (OutArguments.bSampleStacks
        && (OutArguments.SampleStacksIntervalUs < FVoxelStackSampler::MinIntervalUs
            || OutArguments.SampleStacksIntervalUs > FVoxelStackSampler::MaxIntervalUs))
    {
        OutError = FString::Printf(
            TEXT("samplestacks interval must be in [%u,%u] microseconds."),
            FVoxelStackSampler::MinIntervalUs,
            FVoxelStackSampler::MaxIntervalUs);
        return false;
    }
    if (OutArguments.bSurfaceRoughnessOverride
        && !bSurfaceRoughnessParsed)
    {
        OutError = TEXT("surfaceroughness must be a finite number greater than or equal to zero.");
        return false;
    }
    if (OutArguments.bSurfaceRoughnessOverride
        && (!FMath::IsFinite(OutArguments.SurfaceRoughness)
            || OutArguments.SurfaceRoughness < 0.0f))
    {
        OutError = TEXT("surfaceroughness must be finite and greater than or equal to zero.");
        return false;
    }
    if (OutArguments.bTunnelWarpStrengthOverride
        && (!bTunnelWarpStrengthParsed
            || !FMath::IsFinite(OutArguments.TunnelWarpStrength)
            || OutArguments.TunnelWarpStrength < 0.0f))
    {
        OutError = TEXT("tunnelwarp must be finite and greater than or equal to zero.");
        return false;
    }
    if (OutArguments.bRoughnessNoiseTypeOverride && !bRoughnessNoiseTypeParsed)
    {
        OutError = TEXT("roughnesstype must be FBM, Ridged, Mixed, or Cellular.");
        return false;
    }
    if (OutArguments.bRoughnessFrequencyOverride
        && (!bRoughnessFrequencyParsed
            || !FMath::IsFinite(OutArguments.RoughnessFrequency)
            || OutArguments.RoughnessFrequency <= 0.0f))
    {
        OutError = TEXT("roughnessfrequency must be finite and greater than zero.");
        return false;
    }
    if (OutArguments.bTunnelFloorEnabledOverride
        && (!bTunnelFloorEnabledParsed
            || (OutArguments.TunnelFloorEnabled != 0
                && OutArguments.TunnelFloorEnabled != 1)))
    {
        OutError = TEXT("tunnelfloor must be 0 or 1.");
        return false;
    }
    if (OutArguments.bTunnelFloorTerracingOverride
        && (!bTunnelFloorTerracingParsed
            || (OutArguments.TunnelFloorTerracing != 0
                && OutArguments.TunnelFloorTerracing != 1)))
    {
        OutError = TEXT("tunnelfloorterracing must be 0 or 1.");
        return false;
    }
    if (OutArguments.bTunnelFloorStepOverride
        && (!bTunnelFloorStepParsed
            || !FMath::IsFinite(OutArguments.TunnelFloorStep)
            || OutArguments.TunnelFloorStep < 0.0f))
    {
        OutError = TEXT("tunnelfloorstep must be finite and non-negative.");
        return false;
    }
    if (OutArguments.bTunnelFloorMaxLedgeOverride
        && (!bTunnelFloorMaxLedgeParsed
            || !FMath::IsFinite(OutArguments.TunnelFloorMaxLedge)
            || OutArguments.TunnelFloorMaxLedge <= 0.0f))
    {
        OutError = TEXT("tunnelfloormaxledge must be finite and greater than zero.");
        return false;
    }
    if (OutArguments.bTunnelFloorGentleOverride
        && (!bTunnelFloorGentleParsed
            || !FMath::IsFinite(OutArguments.TunnelFloorGentle)
            || OutArguments.TunnelFloorGentle < 0.0f
            || OutArguments.TunnelFloorGentle
                > VoxelPassageGeometry::TunnelFloorGentleSlopeMaximumDegrees))
    {
        OutError = TEXT("tunnelfloorgentle must be finite degrees in [0,90].");
        return false;
    }
    if (OutArguments.bTunnelFloorLedgesOverride
        && (!bTunnelFloorLedgesParsed
            || OutArguments.TunnelFloorLedges < 0
            || OutArguments.TunnelFloorLedges > 4096))
    {
        OutError = TEXT("tunnelfloorledges must be an integer in [0,4096].");
        return false;
    }
    if (OutArguments.bTunnelFloorMaxLedgesOverride
        && (!bTunnelFloorMaxLedgesParsed
            || OutArguments.TunnelFloorMaxLedges < 1
            || OutArguments.TunnelFloorMaxLedges > 4096))
    {
        OutError = TEXT("tunnelfloormaxledges must be an integer in [1,4096].");
        return false;
    }
    if (OutArguments.bRoomMouthRiseOverride
        && (!bRoomMouthRiseParsed
            || !FMath::IsFinite(OutArguments.RoomMouthRise)
            || OutArguments.RoomMouthRise < 0.0f
            || OutArguments.RoomMouthRise > 1.0f))
    {
        OutError = TEXT("roommouthrise must be finite and in [0,1].");
        return false;
    }
    if (OutArguments.bRoomMouthRiseBlendOverride
        && (!bRoomMouthRiseBlendParsed
            || !FMath::IsFinite(OutArguments.RoomMouthRiseBlend)
            || OutArguments.RoomMouthRiseBlend < 8.0f
            || OutArguments.RoomMouthRiseBlend > 128.0f))
    {
        OutError = TEXT("roommouthriseblend must be finite and in [8,128].");
        return false;
    }
    if (OutArguments.bPassageFloorWritesOverride
        && (!bPassageFloorWritesParsed
            || (OutArguments.PassageFloorWrites != 0
                && OutArguments.PassageFloorWrites != 1)))
    {
        OutError = TEXT("passagefloorwrites must be 0 or 1.");
        return false;
    }
    if (OutArguments.bRenderCameraOverride && !bRenderCameraParsed)
    {
        OutError = TEXT("rendercamera must be three finite comma-separated voxel coordinates.");
        return false;
    }
    if (OutArguments.bRenderTargetOverride && !bRenderTargetParsed)
    {
        OutError = TEXT("rendertarget must be three finite comma-separated voxel coordinates.");
        return false;
    }
    if (OutArguments.bDensitySlice && !bDensitySliceParsed)
    {
        OutError = TEXT(
            "densityslice must be origin x,y,z, direction x,y,z, sample count, and positive step.");
        return false;
    }

    if (OutText.IsEmpty())
    {
        OutText = FPaths::Combine(
            VoxelForgeSavedRoot(),
            FString::Printf(TEXT("Explore/seed%d_%s_slot%d"),
                OutArguments.Seed,
                ArchetypeName(OutArguments.Archetype),
                OutArguments.Slot));
    }
    if (FPaths::IsRelative(OutText))
    {
        OutError = FString::Printf(
            TEXT("out must be an absolute path under '%s'."), *VoxelForgeSavedRoot());
        return false;
    }
    OutArguments.OutDirectory = FPaths::ConvertRelativePathToFull(OutText);
    FPaths::NormalizeDirectoryName(OutArguments.OutDirectory);
    if (!IsUnderVoxelForgeSaved(OutArguments.OutDirectory))
    {
        OutError = FString::Printf(
            TEXT("out must be an absolute path under '%s' (got '%s')."),
            *VoxelForgeSavedRoot(), *OutArguments.OutDirectory);
        return false;
    }
    return true;
}

VoxelDensityProfile::EMode ExploreProfileMode(const FExploreArguments& Arguments)
{
    if (Arguments.bPerfAttribution)
    {
        return VoxelDensityProfile::EMode::Attribution;
    }
    return Arguments.bProfileDensityFull
        ? VoxelDensityProfile::EMode::Full
        : VoxelDensityProfile::EMode::Sampled;
}

struct FExploreBudget
{
    double StartSeconds = 0.0;
    double LimitSeconds = 0.0;
    bool bTruncated = false;
    FString TruncatedDuring;
    TArray<FString> CompletedModes;

    FExploreBudget(double InStartSeconds, double InLimitSeconds)
        : StartSeconds(InStartSeconds)
        , LimitSeconds(InLimitSeconds)
    {
    }

    double ElapsedSeconds() const
    {
        return FPlatformTime::Seconds() - StartSeconds;
    }

    double RemainingSeconds() const
    {
        return LimitSeconds - ElapsedSeconds();
    }

    bool ShouldStop(const TCHAR* Phase)
    {
        if (bTruncated)
        {
            return true;
        }

        // Leave a small deterministic cleanup window for the current phase to close files and
        // emit the report. The owner-facing hard ceiling is still enforced by the argument cap at
        // 30 minutes; the default 25-minute budget leaves substantially more headroom.
        constexpr double CleanupReserveSeconds = 0.25;
        if (RemainingSeconds() <= CleanupReserveSeconds)
        {
            bTruncated = true;
            TruncatedDuring = Phase != nullptr ? FString(Phase) : TEXT("unknown");
            UE_LOG(LogTemp, Warning,
                TEXT("[VoxelForgeExplore] budget reached during %s; keeping completed artifacts."),
                *TruncatedDuring);
            return true;
        }
        return false;
    }

    void CompleteMode(const TCHAR* Mode)
    {
        if (Mode == nullptr || bTruncated)
        {
            return;
        }
        CompletedModes.AddUnique(FString(Mode));
    }
};

struct FExploreMeshTriangle
{
    FVector A = FVector::ZeroVector;
    FVector B = FVector::ZeroVector;
    FVector C = FVector::ZeroVector;
    FVector NormalA = FVector::UpVector;
    FVector NormalB = FVector::UpVector;
    FVector NormalC = FVector::UpVector;
    FVector Min = FVector::ZeroVector;
    FVector Max = FVector::ZeroVector;
    FVector Centre = FVector::ZeroVector;
    FVector Normal = FVector::UpVector;
};

struct FExploreMeshBvhNode
{
    FVector Min = FVector::ZeroVector;
    FVector Max = FVector::ZeroVector;
    int32 Left = INDEX_NONE;
    int32 Right = INDEX_NONE;
    int32 FirstTriangle = 0;
    int32 TriangleCount = 0;

    bool IsLeaf() const
    {
        return Left == INDEX_NONE && Right == INDEX_NONE;
    }
};

struct FExploreWorld
{
    TStrongObjectPtr<UVoxelSettings> Settings;
    TStrongObjectPtr<UVoxelStrateManager> Manager;
    TStrongObjectPtr<UVoxelDiffLayer> DiffLayer;
    TStrongObjectPtr<UVoxelGenerator> Generator;
    TStrongObjectPtr<UVoxelMarchingCubesMesher> Mesher;
    TArray<TStrongObjectPtr<UVoxelStrateDefinition>> Definitions;

    // One canonical mesh cache for this commandlet run. Render and export consume these exact
    // triangles; neither path is allowed to ask the density field once per pixel.
    FVoxelMeshData ExploreMesh;
    FVoxelSharedDensityGrid ExploreSharedDensityGrid;
    FIntVector ExploreMeshOrigin = FIntVector::ZeroValue;
    int32 ExploreMeshSize = 0;
    int32 ExploreMeshTileCount = 0;
    int32 ExploreMeshTilesCompleted = 0;
    // Per-tile geometry identity is retained in canonical Z/Y/X order so an optimization can be
    // compared without treating one aggregate hash or triangle total as a shape measurement.
    TArray<int32> ExploreTileTriangleCounts;
    TArray<FString> ExploreTileGeometryHashes;
    double ExploreMeshSeconds = 0.0;
    // Exact wall-clock partition of ExploreMeshSeconds.  The first three fields end at the
    // parallel tile launch; merge closes the mesh clock.  Remainder is intentionally retained
    // instead of rounding the ledger to 100%.
    double ExploreMeshPreparationSeconds = 0.0;
    double ExploreMeshPreTileSetupSeconds = 0.0;
    double ExploreMeshMergeSeconds = 0.0;
    double ExploreMeshAccountingRemainderSeconds = 0.0;
    double ExploreMeshHashSeconds = 0.0;
    double ExploreDensityGridSeconds = 0.0;
    int64 ExploreDensityGridTotalSamples = 0;
    int64 ExploreDensityGridUniqueSamples = 0;
    int64 ExploreDensityGridDuplicateSamplesBefore = 0;
    int64 ExploreDensityGridDuplicateSamplesAfter = 0;
    bool bExploreDensityGridReused = false;
    int32 ExploreMeshTaskWorkerCount = 0;
    int32 ExploreMeshTaskJobCount = 0;
    int32 ExploreMeshTaskMinBatchSize = 1;
    double ExploreMeshTaskMinSeconds = 0.0;
    double ExploreMeshTaskMeanSeconds = 0.0;
    double ExploreMeshTaskMaxSeconds = 0.0;
    double ExploreMeshTaskSumSeconds = 0.0;
    double ExploreMeshTaskWallSeconds = 0.0;
    double ExploreMeshTaskLaunchOverheadSeconds = 0.0;
    bool bExploreMeshBuilt = false;
    bool bExploreMeshComplete = false;
    FString ExploreMeshError;
    FString ExploreGeometryHash;

    // A deterministic CPU acceleration structure over the canonical triangles. It is built once
    // after meshing and reused by every viewpoint; no density query is reachable from raster.
    TArray<FExploreMeshTriangle> ExploreTriangles;
    TArray<int32> ExploreTriangleOrder;
    TArray<FExploreMeshBvhNode> ExploreBvhNodes;
    int32 ExploreBvhRoot = INDEX_NONE;
    double ExploreAccelerationSeconds = 0.0;
    bool bExploreAccelerationBuilt = false;

    int32 TargetBottomWorldZ = 0;
    int32 TargetTopWorldZ = 0;
    float TargetBoundarySealThickness = 4.0f;

    bool Build(const FExploreArguments& Arguments, FString& OutError)
    {
        const bool bUseAuthoredSettings = !Arguments.SettingsReference.IsEmpty();
        const bool bUseAuthoredStrate = !Arguments.StrateReference.IsEmpty();
        UVoxelStrateDefinition* AuthoredDefinition = nullptr;
        if (bUseAuthoredStrate)
        {
            AuthoredDefinition = LoadObject<UVoxelStrateDefinition>(
                nullptr, *Arguments.StrateReference);
            if (AuthoredDefinition == nullptr)
            {
                OutError = FString::Printf(
                    TEXT("Could not load staged strate asset '%s'."),
                    *Arguments.StrateReference);
                return false;
            }
        }

        if (bUseAuthoredSettings)
        {
            UVoxelSettings* AuthoredSettings = LoadObject<UVoxelSettings>(
                nullptr, *Arguments.SettingsReference);
            if (AuthoredSettings == nullptr)
            {
                OutError = FString::Printf(
                    TEXT("Could not load staged settings asset '%s'."),
                    *Arguments.SettingsReference);
                return false;
            }
            Settings = TStrongObjectPtr<UVoxelSettings>(
                DuplicateObject<UVoxelSettings>(AuthoredSettings, GetTransientPackage()));
            if (!Settings.IsValid())
            {
                OutError = TEXT("Could not duplicate the staged settings asset into the transient package.");
                return false;
            }
        }
        else
        {
            Settings = TStrongObjectPtr<UVoxelSettings>(
                NewObject<UVoxelSettings>(GetTransientPackage(), NAME_None, RF_Transient));
        }

        const int32 NumStrates = bUseAuthoredSettings
            ? (Arguments.bGameRuntimeConfig
                ? FMath::Max(Settings->TotalStrates, 1)
                : FMath::Max(Settings->TotalStrates, Arguments.Slot + 2))
            : Arguments.Slot + 2;
        if (NumStrates > MaxSyntheticStrates)
        {
            OutError = TEXT("The synthetic layout would exceed the commandlet strate cap.");
            return false;
        }

        if (!bUseAuthoredSettings)
        {
            Settings->Seed = Arguments.Seed;
            Settings->TotalStrates = NumStrates;
            Settings->InterStrateGapChunks = 0;
            Settings->WorldRadiusVoxels = 0.0f;
            Settings->EdgeSealThickness = 64.0f;
            Settings->OriginSpineRadius = 14.0f;
            Settings->bOpenSurfaceEntry = true;
        }
        else if (Arguments.bSeedOverride)
        {
            Settings->Seed = Arguments.Seed;
        }
        // The transient fixed-definition layout may need to extend an authored settings asset
        // for a requested interior slot. Keep that duplicate's advertised count consistent; the
        // loaded package remains untouched.
        Settings->TotalStrates = NumStrates;

        if (bUseAuthoredStrate)
        {
            // The owner’s snapshot states that every slot uses DA_Strate3. Clone it per slot so
            // commandlet overrides never mutate a loaded package or leak between slots.
            Settings->StratePool.Reset();
            Settings->FixedStrates.Reset();
        }
        Definitions.Reserve(NumStrates);
        for (int32 Index = 0; Index < NumStrates; ++Index)
        {
            UVoxelStrateDefinition* Definition = bUseAuthoredStrate
                ? DuplicateObject<UVoxelStrateDefinition>(
                    AuthoredDefinition, GetTransientPackage())
                : NewObject<UVoxelStrateDefinition>(
                    GetTransientPackage(), NAME_None, RF_Transient);
            if (Definition == nullptr)
            {
                OutError = FString::Printf(
                    TEXT("Could not create transient strate definition for slot %d."), Index);
                return false;
            }
            if (!bUseAuthoredStrate)
            {
                Definition->StrateName = FText::FromString(FString::Printf(
                    TEXT("VoxelForgeExplore_%s_slot%d"),
                    ArchetypeName(Index == Arguments.Slot
                        ? Arguments.Archetype
                        : ECaveGeneratorType::TunnelNetwork),
                    Index));
                Definition->StrateDescription = FText::FromString(
                    TEXT("Transient, deterministic commandlet definition."));
                // The commandlet's acceptance sweep uses the owner-facing base spacing:
                // 4 chunks * 32 voxels * 0.25 m = 32 m per strate. Production assets may be taller;
                // this keeps the measured tunnel arithmetic tied to the stated ~32 m descent.
                Definition->StrateHeightInChunks = 4;
                Definition->TransitionType = EVoxelStrateTransition::Hard;
                Definition->GeneratorType = Index == Arguments.Slot
                    ? Arguments.Archetype
                    : ECaveGeneratorType::TunnelNetwork;
                if (Arguments.bWormsEnabledOverride)
                {
                    Definition->bEnableWorms = Arguments.bWormsEnabled;
                }
                if (Arguments.bWormStrengthOverride
                    && (Definition->GeneratorType == ECaveGeneratorType::TunnelNetwork
                        || Definition->GeneratorType == ECaveGeneratorType::Underwater))
                {
                    Definition->GenerationParams.WormStrength = Arguments.WormStrength;
                }
            }

            const TSoftObjectPtr<UVoxelStrateDefinition> SoftDefinition(Definition);
            Settings->FixedStrates.Add(Index, SoftDefinition);
            if (!bUseAuthoredStrate)
            {
                Settings->StratePool.Add(SoftDefinition);
            }
            Definitions.Add(TStrongObjectPtr<UVoxelStrateDefinition>(Definition));
        }

        auto ApplyTargetOverrides = [&Arguments](UVoxelStrateDefinition* Definition) -> bool
        {
            if (Definition == nullptr) { return false; }
            const ECaveGeneratorType TargetArchetype = Definition->GeneratorType;
            if (Arguments.bSurfaceRoughnessOverride)
            {
                switch (TargetArchetype)
                {
                case ECaveGeneratorType::FlatPlain:
                case ECaveGeneratorType::CrystalChamber:
                    Definition->SlabParams.FloorRoughness = Arguments.SurfaceRoughness;
                    Definition->SlabParams.CeilingRoughness = Arguments.SurfaceRoughness;
                    break;
                case ECaveGeneratorType::Maze:
                    Definition->MazeParams.SurfaceRoughness = Arguments.SurfaceRoughness;
                    break;
                case ECaveGeneratorType::SurfaceWorld:
                    Definition->SurfaceParams.SurfaceRoughness = Arguments.SurfaceRoughness;
                    break;
                case ECaveGeneratorType::VerticalShafts:
                    Definition->VerticalShaftParams.SurfaceRoughness = Arguments.SurfaceRoughness;
                    break;
                case ECaveGeneratorType::FloatingIslands:
                    Definition->FloatingIslandParams.SurfaceRoughness = Arguments.SurfaceRoughness;
                    break;
                case ECaveGeneratorType::TunnelNetwork:
                case ECaveGeneratorType::Underwater:
                default:
                    Definition->GenerationParams.SurfaceRoughness = Arguments.SurfaceRoughness;
                    break;
                }
            }
            if (Arguments.bRoughnessNoiseTypeOverride
                || Arguments.bRoughnessFrequencyOverride)
            {
                if (TargetArchetype != ECaveGeneratorType::TunnelNetwork
                    && TargetArchetype != ECaveGeneratorType::Underwater)
                {
                    return false;
                }
                if (Arguments.bRoughnessNoiseTypeOverride)
                {
                    Definition->GenerationParams.RoughnessNoiseType = Arguments.RoughnessNoiseType;
                }
                if (Arguments.bRoughnessFrequencyOverride)
                {
                    Definition->GenerationParams.RoughnessFrequency = Arguments.RoughnessFrequency;
                }
            }
            FStrateGenerationParams& TunnelParams = Definition->GenerationParams;
            if (Arguments.bTunnelWarpStrengthOverride)
            {
                if (TargetArchetype != ECaveGeneratorType::TunnelNetwork
                    && TargetArchetype != ECaveGeneratorType::Underwater)
                {
                    return false;
                }
                TunnelParams.TunnelWarpStrength = Arguments.TunnelWarpStrength;
            }
            if (Arguments.bTunnelFloorEnabledOverride)
            {
                // Retain the command-line spelling for old probes, but do not feed the removed
                // floor switch into generation.  The serialized property has the same
                // compatibility-only treatment in UVoxelStrateDefinition::PostLoad.
            }
            if (Arguments.bTunnelFloorTerracingOverride)
            {
                TunnelParams.bTunnelFloorTerracingEnabled = Arguments.TunnelFloorTerracing != 0;
            }
            if (Arguments.bTunnelFloorStepOverride)
            {
                TunnelParams.TunnelFloorTerraceStepHeight = Arguments.TunnelFloorStep;
            }
            if (Arguments.bTunnelFloorMaxLedgeOverride)
            {
                TunnelParams.TunnelFloorMaxLedgeHeight = Arguments.TunnelFloorMaxLedge;
            }
            if (Arguments.bTunnelFloorGentleOverride)
            {
                TunnelParams.TunnelFloorGentleSlopeThreshold = Arguments.TunnelFloorGentle;
            }
            if (Arguments.bTunnelFloorLedgesOverride)
            {
                TunnelParams.TunnelFloorLedgeCountPreference = Arguments.TunnelFloorLedges;
            }
            if (Arguments.bTunnelFloorMaxLedgesOverride)
            {
                TunnelParams.TunnelFloorMaxLedges = Arguments.TunnelFloorMaxLedges;
            }
            if (Arguments.bRoomMouthRiseOverride)
            {
                TunnelParams.RoomMouthRiseStrength = Arguments.RoomMouthRise;
            }
            if (Arguments.bRoomMouthRiseBlendOverride)
            {
                TunnelParams.RoomMouthRiseBlendVoxels = Arguments.RoomMouthRiseBlend;
            }
            return true;
        };
        if (!Definitions.IsValidIndex(Arguments.Slot)
            || !ApplyTargetOverrides(Definitions[Arguments.Slot].Get()))
        {
            OutError = TEXT("The target definition rejected a commandlet override.");
            return false;
        }

        Manager = TStrongObjectPtr<UVoxelStrateManager>(
            NewObject<UVoxelStrateManager>(GetTransientPackage(), NAME_None, RF_Transient));
        if (!Manager->Initialize(Settings.Get(), Settings->Seed))
        {
            OutError = TEXT("UVoxelStrateManager::Initialize refused the transient layout.");
            return false;
        }
        if (Arguments.bPassageFloorWritesOverride)
        {
            Manager->SetPassageSupportFloorWritesEnabledForDiagnostics(
                Arguments.PassageFloorWrites != 0);
        }

        if (!Manager->GetLayout().IsValidIndex(Arguments.Slot))
        {
            OutError = TEXT("The requested target slot did not enter the manager layout.");
            return false;
        }
        const FStrateSlot& Target = Manager->GetLayout()[Arguments.Slot];
        if (Target.Definition == nullptr)
        {
            OutError = TEXT("The requested target slot has no resolved definition.");
            return false;
        }
        const ECaveGeneratorType TargetArchetype = Target.Definition->GeneratorType;
        const FStrateGenerationParams& ReportParams = Target.Definition->GenerationParams;
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeExplore][OwnerAssets] strate=%s settings=%s slot=%d "
                 "seed=%d height_chunks=%d archetype=%s "
                 "floor_switch_ignored=1 floor_terracing=%d floor_step=%.9g max_ledge=%.9g "
                 "gentle_slope_degrees=%.9g gentle_gradient=%.9g route_cap=%.9g "
                 "wind_wave_cap=%d "
                 "ledge_preference=%d max_ledges=%d tunnel_warp=%.9g terrain_ops=%d terrace_step=%.9g "
                 "layer_spacing=%.9g rib_spacing=%.9g"),
            bUseAuthoredStrate ? *Arguments.StrateReference : TEXT("synthetic"),
            bUseAuthoredSettings ? *Arguments.SettingsReference : TEXT("synthetic"),
            Arguments.Slot, Settings->Seed, Target.Definition->StrateHeightInChunks,
            ArchetypeName(TargetArchetype),
            ReportParams.bTunnelFloorTerracingEnabled ? 1 : 0,
            ReportParams.TunnelFloorTerraceStepHeight,
            ReportParams.TunnelFloorMaxLedgeHeight,
            ReportParams.TunnelFloorGentleSlopeThreshold,
            VoxelPassageGeometry::TunnelFloorGradientFromDegrees(
                ReportParams.TunnelFloorGentleSlopeThreshold),
            VoxelPassageGeometry::TunnelFloorMaximumRouteLengthVoxels,
            VoxelPassageGeometry::TunnelFloorMaximumWindWaves,
            ReportParams.TunnelFloorLedgeCountPreference,
            ReportParams.TunnelFloorMaxLedges,
            ReportParams.TunnelWarpStrength,
            Target.Definition->TerrainOperations.Num(),
            ReportParams.TerraceStepHeight,
            ReportParams.LayerLineSpacing,
            ReportParams.RibbingSpacing);
        TargetBottomWorldZ = Target.BottomChunkZ * CHUNK_SIZE;
        TargetTopWorldZ = (Target.TopChunkZ + 1) * CHUNK_SIZE;
        TargetBoundarySealThickness = BoundarySealForArchetype(
            *Target.Definition, TargetArchetype);
        if (TargetTopWorldZ <= TargetBottomWorldZ)
        {
            OutError = TEXT("The target strate has no positive voxel-space height.");
            return false;
        }

        DiffLayer = TStrongObjectPtr<UVoxelDiffLayer>(
            NewObject<UVoxelDiffLayer>(GetTransientPackage(), NAME_None, RF_Transient));
        Generator = TStrongObjectPtr<UVoxelGenerator>(
            NewObject<UVoxelGenerator>(GetTransientPackage(), NAME_None, RF_Transient));
        Generator->InitializeSettings(Settings.Get());
        Generator->SetStrateManager(Manager.Get());
        Generator->SetDiffLayer(DiffLayer.Get());
        Mesher = TStrongObjectPtr<UVoxelMarchingCubesMesher>(
            NewObject<UVoxelMarchingCubesMesher>(GetTransientPackage(), NAME_None, RF_Transient));
        Mesher->SetGenerator(Generator.Get());
        Mesher->bUseBlockEarlyOut = Arguments.bBlockEarlyOut;
        if (Arguments.bGameRuntimeConfig)
        {
            Mesher->bGenerateSkirts = Settings->bGenerateSkirts;
            Mesher->SkirtCells = Settings->SkirtCells;
            Mesher->LODOctaveDrop = Settings->LODOctaveDrop;
        }

        if (Settings->WorldRadiusVoxels != 0.0f
            || Generator->WorldRadiusVoxels != 0.0f
            || Settings->InterStrateGapChunks != 0)
        {
            OutError = TEXT(
                "Explorer invariant failed: WorldRadiusVoxels must stay 0 and lateral regions must stay gated off.");
            return false;
        }
        return true;
    }
};

struct FRegionEvalPass
{
    VoxelForgeRegionEval::FTiming Timing;
    VoxelForgeRegionEval::FCandidateVisits Visits;
    TArray<float> Densities;
    TArray<int64> SampleIndices;
    FIntVector Origin = FIntVector::ZeroValue;
    int32 RecipeIndex = INDEX_NONE;
    uint32 RecipeHash = 0;
    int32 PassageCount = 0;
    int32 EditChunkCount = 0;
    int32 TargetedSampleCount = 0;
    double WorldPrepareSeconds = 0.0;
    FString StartedUtc;
    FString EndedUtc;
};

struct FRegionEvalStackSamplerSession
{
    bool bStarted = false;

    ~FRegionEvalStackSamplerSession()
    {
        if (bStarted)
        {
            FVoxelStackSampler::Get().StopAndWrite();
        }
    }

    bool Start(uint32 IntervalUs, const FString& OutputDirectory,
               const TCHAR* Scenario = TEXT("region_eval_live_ring"))
    {
        bStarted = FVoxelStackSampler::Get().Start(
            IntervalUs, OutputDirectory, Scenario);
        return bStarted;
    }

    bool Stop(FVoxelStackSampler::FSummary& OutSummary)
    {
        if (!bStarted)
        {
            return false;
        }
        OutSummary = FVoxelStackSampler::Get().StopAndWrite();
        bStarted = false;
        return OutSummary.bOutputWritten
            && OutSummary.RegisteredThreadSamples > 0
            && OutSummary.RetainedSamples > 0;
    }
};

int32 FindRoomGraphRecipeIndex(int32 Seed)
{
    for (int32 Index = 0; Index < 64; ++Index)
    {
        const FVoxelOpStackRecipe Recipe = VF_RollStrateStructure(Seed, Index);
        if (Recipe.ShapeSource.OpClass == EVoxelStrateOpClass::RoomGraphSource)
        {
            return Index;
        }
    }
    return INDEX_NONE;
}

bool PrepareRegionEvalWorld(
    FExploreWorld& World,
    const FExploreArguments& BaseArguments,
    int32 Seed,
    int32& OutRecipeIndex,
    uint32& OutRecipeHash,
    int32& OutEditChunkCount,
    FString& OutError)
{
    FExploreArguments Arguments = BaseArguments;
    Arguments.Seed = Seed;
    Arguments.bSeedOverride = true;
    Arguments.bRender = false;
    Arguments.bWalk = false;
    Arguments.bExport = false;
    Arguments.bBlockEarlyOut = false;
    if (!World.Build(Arguments, OutError))
    {
        return false;
    }
    if (!World.Definitions.IsValidIndex(Arguments.Slot))
    {
        OutError = TEXT("Region evaluator target definition is missing.");
        return false;
    }
    UVoxelStrateDefinition* Definition = World.Definitions[Arguments.Slot].Get();
    if (Definition == nullptr || Definition->GeneratorType != ECaveGeneratorType::TunnelNetwork)
    {
        OutError = TEXT("Region evaluator requires the owner TunnelNetwork target slot.");
        return false;
    }

    OutRecipeIndex = FindRoomGraphRecipeIndex(Seed);
    if (OutRecipeIndex == INDEX_NONE)
    {
        OutError = FString::Printf(
            TEXT("No RoomGraphSource recipe found in the 64-entry structure roll for seed %d."), Seed);
        return false;
    }
    const FVoxelOpStackRecipe Recipe = VF_RollStrateStructure(Seed, OutRecipeIndex);
    OutRecipeHash = VF_HashStrateStructureRecipe(Recipe);

    // Make the selected RoomGraph recipe exercise the authored warp path. The definition is a
    // transient duplicate of DA_Strate3, and both the live and prepared passes receive the same
    // operator parameters and recipe.
    FVoxelStrateArchetypeParams NativeParams;
    NativeParams.TunnelNetworkParams = Definition->GenerationParams;
    NativeParams.TunnelNetworkParams.TunnelWarpStrength = FMath::Max(
        NativeParams.TunnelNetworkParams.TunnelWarpStrength, 1.25f);
    NativeParams.SlabParams = Definition->SlabParams;
    NativeParams.MazeParams = Definition->MazeParams;
    NativeParams.SurfaceParams = Definition->SurfaceParams;
    NativeParams.VerticalShaftParams = Definition->VerticalShaftParams;
    NativeParams.FloatingIslandParams = Definition->FloatingIslandParams;
    FString ComposerError;
    if (!World.Manager->SetComposerOverrideForStrate(
            Arguments.Slot, Seed, Definition->GeneratorType,
            NativeParams, true, &Recipe, ComposerError))
    {
        OutError = FString::Printf(
            TEXT("Could not install rolled composer recipe for seed %d: %s"),
            Seed, *ComposerError);
        return false;
    }

    const int32 CenterZ = (World.TargetTopWorldZ + World.TargetBottomWorldZ) / 2;
    FVoxelModification Carve;
    Carve.Center = FVector(8.0f, 4.0f, static_cast<float>(CenterZ));
    Carve.Radius = 6.0f;
    Carve.Strength = -12.0f;
    Carve.Shape = EVoxelBrushShape::Sphere;
    const TArray<FIntVector> CarvedChunks = World.DiffLayer->ApplyModification(Carve);
    FVoxelModification Fill;
    Fill.Center = FVector(-12.0f, 6.0f, static_cast<float>(CenterZ - 10));
    Fill.Radius = 4.0f;
    Fill.Strength = 12.0f;
    Fill.Shape = EVoxelBrushShape::Sphere;
    const TArray<FIntVector> FilledChunks = World.DiffLayer->ApplyModification(Fill);
    if (CarvedChunks.IsEmpty() || FilledChunks.IsEmpty())
    {
        OutError = TEXT("Transient player carve/fill edits did not enter the diff layer.");
        return false;
    }
    OutEditChunkCount = CarvedChunks.Num() + FilledChunks.Num();

    int32 RecipeSeed = 0;
    ECaveGeneratorType RecipeArchetype = ECaveGeneratorType::TunnelNetwork;
    FVoxelStrateArchetypeParams ResolvedParams;
    FVoxelOpStackRecipe ResolvedRecipe;
    const int32 ChunkZ = FMath::FloorToInt(static_cast<float>(CenterZ) / CHUNK_SIZE);
    if (!World.Manager->GetRecipeForChunk(
            FIntVector(0, 0, ChunkZ), RecipeSeed, RecipeArchetype,
            ResolvedParams, ResolvedRecipe)
        || !VF_AreStrateStructureRecipesIdentical(Recipe, ResolvedRecipe))
    {
        OutError = TEXT("Composer recipe was not active on the target density lattice.");
        return false;
    }
    return true;
}

void AddRegionSampleIndex(
    TSet<int64>& Unique,
    int32 X, int32 Y, int32 Z,
    FIntVector Origin, int32 Dimension)
{
    const int32 LX = X - Origin.X;
    const int32 LY = Y - Origin.Y;
    const int32 LZ = Z - Origin.Z;
    if (LX >= 0 && LX < Dimension && LY >= 0 && LY < Dimension
        && LZ >= 0 && LZ < Dimension)
    {
        Unique.Add(VoxelForgeRegionEval::LinearIndex(LX, LY, LZ, Dimension));
    }
}

TArray<int64> BuildRegionEvalSampleIndices(
    const FExploreWorld& World,
    FIntVector Origin,
    int32 Dimension,
    int32 RequestedRandomSamples,
    int32 Seed,
    int32& OutTargetedSamples)
{
    const int64 Total = static_cast<int64>(Dimension) * Dimension * Dimension;
    const int32 RandomCount = FMath::Clamp(RequestedRandomSamples, 1, static_cast<int32>(Total));
    TArray<int64> Indices;
    Indices.Reserve(RandomCount + 50000);

    auto Gcd = [](int64 A, int64 B)
    {
        while (B != 0)
        {
            const int64 R = A % B;
            A = B;
            B = R;
        }
        return A;
    };
    int64 Multiplier = 104729;
    while (Gcd(Multiplier, Total) != 1)
    {
        Multiplier += 2;
    }
    const int64 Offset = (static_cast<int64>(Seed) * 48271ll) % Total;
    for (int32 Sample = 0; Sample < RandomCount; ++Sample)
    {
        Indices.Add((static_cast<int64>(Sample) * Multiplier + Offset) % Total);
    }

    TSet<int64> Unique;
    Unique.Reserve(50000);
    for (const int64 Index : Indices)
    {
        Unique.Add(Index);
    }
    const int32 RandomUniqueCount = Unique.Num();

    // Dense probes around both edited volumes.
    const int32 CenterZ = (World.TargetTopWorldZ + World.TargetBottomWorldZ) / 2;
    const FVector EditCenters[] = {
        FVector(8.0f, 4.0f, static_cast<float>(CenterZ)),
        FVector(-12.0f, 6.0f, static_cast<float>(CenterZ - 10)),
    };
    for (const FVector& Center : EditCenters)
    {
        const int32 CX = FMath::FloorToInt(Center.X);
        const int32 CY = FMath::FloorToInt(Center.Y);
        const int32 CZ = FMath::FloorToInt(Center.Z);
        for (int32 Z = CZ - 8; Z <= CZ + 8; ++Z)
        {
            for (int32 Y = CY - 8; Y <= CY + 8; ++Y)
            {
                for (int32 X = CX - 8; X <= CX + 8; ++X)
                {
                    AddRegionSampleIndex(Unique, X, Y, Z, Origin, Dimension);
                }
            }
        }
    }

    // Include lattice sites around each authored route tube, landing room, and floor anchor.
    for (const FVoxelPassage& Passage : World.Manager->GetPassages())
    {
        TArray<FVector> Anchors;
        Anchors.Add(Passage.UpperPoint);
        Anchors.Add(Passage.LowerPoint);
        Anchors.Add(Passage.UpperLanding.StandingPoint);
        Anchors.Add(Passage.UpperLanding.DoorPoint);
        Anchors.Add(Passage.LowerLanding.StandingPoint);
        Anchors.Add(Passage.LowerLanding.DoorPoint);
        Anchors.Append(Passage.ControlPoints);
        for (const FVector& Anchor : Anchors)
        {
            const int32 AX = FMath::FloorToInt(Anchor.X);
            const int32 AY = FMath::FloorToInt(Anchor.Y);
            const int32 AZ = FMath::FloorToInt(Anchor.Z);
            for (int32 Z = AZ - 3; Z <= AZ + 3; ++Z)
            {
                for (int32 Y = AY - 3; Y <= AY + 3; ++Y)
                {
                    for (int32 X = AX - 3; X <= AX + 3; ++X)
                    {
                        AddRegionSampleIndex(Unique, X, Y, Z, Origin, Dimension);
                    }
                }
            }
        }
    }

    // Both strate boundaries are swept across the horizontal region, including ±3 lattice rows.
    const int32 Boundaries[] = { World.TargetTopWorldZ, World.TargetBottomWorldZ };
    for (const int32 BoundaryZ : Boundaries)
    {
        for (int32 Dz = -3; Dz <= 3; ++Dz)
        {
            for (int32 Y = -128; Y <= 128; Y += 8)
            {
                for (int32 X = -128; X <= 128; X += 8)
                {
                    AddRegionSampleIndex(Unique, X, Y, BoundaryZ + Dz, Origin, Dimension);
                }
            }
        }
    }

    Indices = Unique.Array();
    Indices.Sort();
    OutTargetedSamples = FMath::Max(0, Indices.Num() - RandomUniqueCount);
    return Indices;
}

bool RunRegionEvalPass(
    const FExploreArguments& BaseArguments,
    int32 Seed,
    bool bPrepared,
    bool bBrickProgram,
    float ReachScale,
    bool bFullRing,
    const TArray<int64>* RequestedIndices,
    int32 RequestedSamples,
    bool bCountCandidates,
    bool bKeepDensities,
    FRegionEvalPass& OutPass,
    FString& OutError,
    int32 RequestedWorkerCount = VoxelForgeRegionEval::WorkerCount)
{
    OutPass = FRegionEvalPass();
    FExploreWorld World;
    const double PrepareStartSeconds = FPlatformTime::Seconds();
    if (!PrepareRegionEvalWorld(
            World, BaseArguments, Seed, OutPass.RecipeIndex,
            OutPass.RecipeHash, OutPass.EditChunkCount, OutError))
    {
        return false;
    }
    OutPass.WorldPrepareSeconds = FPlatformTime::Seconds() - PrepareStartSeconds;
    OutPass.PassageCount = World.Manager->GetPassages().Num();
    const int32 CenterZ = (World.TargetTopWorldZ + World.TargetBottomWorldZ) / 2;
    OutPass.Origin = FIntVector(-129, -129, CenterZ - 129);
    if (OutPass.PassageCount <= 0)
    {
        OutError = FString::Printf(TEXT("Seed %d generated no inter-strate route passages."), Seed);
        return false;
    }
    if (RequestedIndices != nullptr)
    {
        OutPass.SampleIndices = *RequestedIndices;
    }
    else
    {
        OutPass.SampleIndices = BuildRegionEvalSampleIndices(
            World, OutPass.Origin, VoxelForgeRegionEval::RingDimension,
            RequestedSamples, Seed, OutPass.TargetedSampleCount);
    }
    if (OutPass.SampleIndices.IsEmpty())
    {
        OutError = TEXT("Region evaluator produced an empty correctness sample set.");
        return false;
    }

    OutPass.StartedUtc = FDateTime::UtcNow().ToIso8601();
    const bool bEvaluated = VoxelForgeRegionEval::Evaluate(
        *World.Generator, OutPass.Origin, VoxelForgeRegionEval::RingDimension,
        bFullRing ? nullptr : &OutPass.SampleIndices,
        bFullRing, bPrepared, ReachScale,
        bKeepDensities ? &OutPass.Densities : nullptr,
        OutPass.Timing, bBrickProgram, RequestedWorkerCount);
    OutPass.EndedUtc = FDateTime::UtcNow().ToIso8601();
    if (!bEvaluated)
    {
        OutError = FString::Printf(
            TEXT("Density evaluation failed or emitted a non-finite value (seed %d)."), Seed);
        return false;
    }
    if (bCountCandidates)
    {
        OutPass.Visits = VoxelForgeRegionEval::CountCandidates(
            *World.Generator, OutPass.Origin,
            VoxelForgeRegionEval::RingDimension,
            OutPass.SampleIndices, bPrepared, ReachScale);
        if (OutPass.Visits.SampleCount != OutPass.SampleIndices.Num())
        {
            OutError = TEXT("Candidate counter sweep did not consume the full fixed sample set.");
            return false;
        }
    }
    return true;
}

TSharedRef<FJsonObject> RegionEvalTimingJson(const FRegionEvalPass& Pass, bool bPrepared)
{
    TSharedRef<FJsonObject> Json = MakeShared<FJsonObject>();
    Json->SetStringField(TEXT("path"), Pass.Timing.bBrickProgram
        ? TEXT("editor_region_brick_program")
        : (bPrepared ? TEXT("prepared_8cube_bins") : TEXT("live_GetDensityAt")));
    Json->SetStringField(TEXT("started_utc"), Pass.StartedUtc);
    Json->SetStringField(TEXT("ended_utc"), Pass.EndedUtc);
    Json->SetNumberField(TEXT("worker_count"), Pass.Timing.Workers);
    Json->SetNumberField(TEXT("observed_worker_threads"), Pass.Timing.ObservedWorkerThreads);
    Json->SetNumberField(TEXT("samples"), static_cast<double>(Pass.Timing.SampleCount));
    Json->SetNumberField(TEXT("evaluated_brick_points"), static_cast<double>(Pass.Timing.EvaluatedSamples));
    Json->SetNumberField(TEXT("brick_count"), static_cast<double>(Pass.Timing.BrickCount));
    Json->SetNumberField(TEXT("fallback_points"), static_cast<double>(Pass.Timing.FallbackSamples));
    Json->SetNumberField(TEXT("fallback_share"), Pass.Timing.FallbackShare);
    Json->SetNumberField(TEXT("world_setup_seconds_before_density_ring"), Pass.WorldPrepareSeconds);
    Json->SetNumberField(TEXT("wall_seconds"), Pass.Timing.WallSeconds);
    Json->SetNumberField(TEXT("worker_cpu_seconds"), Pass.Timing.WorkerCpuSeconds);
    Json->SetNumberField(TEXT("worker_cpu_ns_per_sample"), Pass.Timing.NanosecondsPerSample);
    const FString WorkerCpuSource = Pass.Timing.bWorkerCpuFromOsThreadTimes
        ? FString::Printf(TEXT("summed Windows GetThreadTimes user+kernel CPU across %d fixed work partitions"),
            Pass.Timing.Workers)
        : TEXT("summed worker elapsed fallback; OS thread CPU counters unavailable");
    Json->SetStringField(TEXT("worker_cpu_source"), WorkerCpuSource);
    Json->SetStringField(TEXT("quantized_hash_fnv1a64"),
        FString::Printf(TEXT("%016llx"), static_cast<unsigned long long>(Pass.Timing.QuantizedHash)));
    Json->SetStringField(TEXT("raw_float_hash_fnv1a64"),
        FString::Printf(TEXT("%016llx"), static_cast<unsigned long long>(Pass.Timing.RawFloatHash)));
    Json->SetNumberField(TEXT("saturated_samples"), static_cast<double>(Pass.Timing.SaturatedSamples));
    Json->SetNumberField(TEXT("non_finite_samples"), static_cast<double>(Pass.Timing.NonFiniteSamples));
    if (Pass.Visits.SampleCount > 0)
    {
        Json->SetNumberField(TEXT("candidate_visits_per_sample"), Pass.Visits.PerSample);
        Json->SetNumberField(TEXT("room_candidate_visits"), static_cast<double>(Pass.Visits.Room));
        Json->SetNumberField(TEXT("tunnel_candidate_visits"), static_cast<double>(Pass.Visits.Tunnel));
        Json->SetNumberField(TEXT("tunnel_core_candidate_visits"), static_cast<double>(Pass.Visits.TunnelCore));
        Json->SetNumberField(TEXT("passage_candidate_visits"), static_cast<double>(Pass.Visits.Passage));
        Json->SetNumberField(TEXT("tunnel_cache_lookups"), static_cast<double>(Pass.Visits.TunnelCacheLookups));
        Json->SetNumberField(TEXT("tunnel_cache_hits"), static_cast<double>(Pass.Visits.TunnelCacheHits));
        Json->SetNumberField(TEXT("tunnel_cache_misses"), static_cast<double>(Pass.Visits.TunnelCacheMisses));
        Json->SetNumberField(TEXT("sdf_cache_builds"), static_cast<double>(Pass.Visits.SdfCacheBuilds));
        Json->SetNumberField(TEXT("candidate_counter_samples"), static_cast<double>(Pass.Visits.SampleCount));
        Json->SetNumberField(TEXT("attribution_sample_interval"), Pass.Visits.AttributionSampleInterval);
        Json->SetStringField(TEXT("attribution_basis"), TEXT("sampled VoxelDensityProfile phases; diagnostic only, excluded from clean timing"));
        Json->SetNumberField(TEXT("get_density_at_attributed_ns_per_sample"), Pass.Visits.GetDensityAtAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_prologue_attributed_ns_per_sample"), Pass.Visits.DensityPrologueAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_core_attributed_ns_per_sample"), Pass.Visits.DensityCoreAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_disturbances_attributed_ns_per_sample"), Pass.Visits.DensityDisturbancesAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_structural_posts_attributed_ns_per_sample"), Pass.Visits.DensityStructuralPostsAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_boundary_seal_attributed_ns_per_sample"), Pass.Visits.DensityBoundarySealAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_diff_layer_attributed_ns_per_sample"), Pass.Visits.DensityDiffLayerAttributedNsPerSample);
        Json->SetNumberField(TEXT("density_tail_attributed_ns_per_sample"), Pass.Visits.DensityTailAttributedNsPerSample);
    }
    return Json;
}

struct FQuantizedComparison
{
    int64 Disagreements = 0;
    int64 SignDisagreements = 0;
    double MaxAbsoluteFloatDelta = 0.0;
    int64 FirstIndex = INDEX_NONE;
};

FQuantizedComparison CompareQuantizedArrays(
    const TArray<float>& A, const TArray<float>& B,
    const TArray<int64>* LatticeIndices = nullptr)
{
    FQuantizedComparison Result;
    if (A.Num() != B.Num())
    {
        Result.Disagreements = FMath::Max(A.Num(), B.Num());
        return Result;
    }
    for (int32 Index = 0; Index < A.Num(); ++Index)
    {
        bool bSaturatedA = false, bFiniteA = false;
        bool bSaturatedB = false, bFiniteB = false;
        const int16 QA = VoxelForgeRegionEval::QuantizeDensity(A[Index], bSaturatedA, bFiniteA);
        const int16 QB = VoxelForgeRegionEval::QuantizeDensity(B[Index], bSaturatedB, bFiniteB);
        Result.MaxAbsoluteFloatDelta = FMath::Max(
            Result.MaxAbsoluteFloatDelta,
            FMath::Abs(static_cast<double>(A[Index]) - static_cast<double>(B[Index])));
        if (!bFiniteA || !bFiniteB || bSaturatedA || bSaturatedB || QA != QB)
        {
            ++Result.Disagreements;
            if (Result.FirstIndex == INDEX_NONE)
            {
                Result.FirstIndex = LatticeIndices != nullptr
                    ? (*LatticeIndices)[Index] : static_cast<int64>(Index);
            }
        }
        if ((QA < 0) != (QB < 0))
        {
            ++Result.SignDisagreements;
        }
    }
    return Result;
}

TSharedRef<FJsonObject> RegionEvalComparisonJson(const FQuantizedComparison& Comparison)
{
    TSharedRef<FJsonObject> Json = MakeShared<FJsonObject>();
    Json->SetNumberField(TEXT("quantized_disagreements"), static_cast<double>(Comparison.Disagreements));
    Json->SetNumberField(TEXT("quantized_sign_disagreements"), static_cast<double>(Comparison.SignDisagreements));
    Json->SetNumberField(TEXT("max_abs_float_delta"), Comparison.MaxAbsoluteFloatDelta);
    Json->SetNumberField(TEXT("first_disagreement_linear_index"), static_cast<double>(Comparison.FirstIndex));
    return Json;
}

int32 RunRegionEval(const FString& Params)
{
    FExploreArguments Arguments;
    FString Error;
    if (!ParseArguments(Params, Arguments, Error))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] argument error: %s"), *Error);
        return 2;
    }
    int32 RequestedSamples = 262144;
    FParse::Value(*Params, TEXT("regionsamples="), RequestedSamples);
    RequestedSamples = FMath::Clamp(RequestedSamples, 32768, 1000000);
    int32 RequestedWorkerCount = VoxelForgeRegionEval::WorkerCount;
    FParse::Value(*Params, TEXT("regionworkers="), RequestedWorkerCount);
    RequestedWorkerCount = FMath::Clamp(RequestedWorkerCount, 1, 32);
    IFileManager::Get().MakeDirectory(*Arguments.OutDirectory, true);

    if (FParse::Param(*Params, TEXT("regionhashprobe")))
    {
        FRegionEvalStackSamplerSession WorkerHashStackSampler;
        if (Arguments.bSampleStacks
            && !WorkerHashStackSampler.Start(
                Arguments.SampleStacksIntervalUs, Arguments.OutDirectory,
                TEXT("region_eval_brick_worker_hash")))
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] worker hash stack sampler could not be started."));
            return 2;
        }

        FRegionEvalPass WorkerHashPass;
        const bool bHashPassSucceeded = RunRegionEvalPass(
                Arguments, 1337, true, true, 1.0f, true, nullptr,
                RequestedSamples, false, true, WorkerHashPass, Error,
                RequestedWorkerCount);
        bool bStackCaptureSucceeded = true;
        if (Arguments.bSampleStacks)
        {
            FVoxelStackSampler::FSummary StackSummary;
            bStackCaptureSucceeded = WorkerHashStackSampler.Stop(StackSummary);
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeRegionEval] worker-hash stack capture registered=%llu retained=%llu "
                     "raw=%s summary=%s"),
                static_cast<unsigned long long>(StackSummary.RegisteredThreadSamples),
                static_cast<unsigned long long>(StackSummary.RetainedSamples),
                *StackSummary.RawSamplesPath, *StackSummary.SummaryPath);
        }
        if (!bHashPassSucceeded || !bStackCaptureSucceeded)
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] worker hash probe failed: %s"),
                Error.IsEmpty() ? TEXT("stack capture retained no worker samples") : *Error);
            return 2;
        }

        FString ReferenceRawHash;
        FParse::Value(*Params, TEXT("regionreferencehash="), ReferenceRawHash);
        const FString ActualRawHash = FString::Printf(TEXT("%016llx"),
            static_cast<unsigned long long>(WorkerHashPass.Timing.RawFloatHash));
        const bool bHasReferenceHash = !ReferenceRawHash.IsEmpty();
        const bool bMatchesReference = bHasReferenceHash
            && ActualRawHash.Equals(ReferenceRawHash, ESearchCase::IgnoreCase);
        const bool bProbePassed = bMatchesReference
            && WorkerHashPass.Timing.SampleCount
                == static_cast<int64>(VoxelForgeRegionEval::RingDimension)
                    * VoxelForgeRegionEval::RingDimension * VoxelForgeRegionEval::RingDimension
            && WorkerHashPass.Timing.SaturatedSamples == 0
            && WorkerHashPass.Timing.NonFiniteSamples == 0;

        TSharedRef<FJsonObject> ProbeReport = MakeShared<FJsonObject>();
        ProbeReport->SetBoolField(TEXT("pass"), bProbePassed);
        ProbeReport->SetBoolField(TEXT("worker_count_hash_probe"), true);
        ProbeReport->SetNumberField(TEXT("worker_count"), WorkerHashPass.Timing.Workers);
        ProbeReport->SetNumberField(TEXT("observed_worker_threads"),
            WorkerHashPass.Timing.ObservedWorkerThreads);
        ProbeReport->SetNumberField(TEXT("samples"), WorkerHashPass.Timing.SampleCount);
        ProbeReport->SetNumberField(TEXT("brick_count"), WorkerHashPass.Timing.BrickCount);
        ProbeReport->SetNumberField(TEXT("fallback_points"), WorkerHashPass.Timing.FallbackSamples);
        ProbeReport->SetNumberField(TEXT("fallback_share"), WorkerHashPass.Timing.FallbackShare);
        ProbeReport->SetNumberField(TEXT("wall_seconds"), WorkerHashPass.Timing.WallSeconds);
        ProbeReport->SetNumberField(TEXT("worker_cpu_seconds"), WorkerHashPass.Timing.WorkerCpuSeconds);
        ProbeReport->SetStringField(TEXT("reference_raw_float_hash_fnv1a64"), ReferenceRawHash);
        ProbeReport->SetStringField(TEXT("raw_float_hash_fnv1a64"), ActualRawHash);
        ProbeReport->SetBoolField(TEXT("matches_reference"), bMatchesReference);

        FString ProbeJsonText;
        TSharedRef<TJsonWriter<>> ProbeWriter = TJsonWriterFactory<>::Create(&ProbeJsonText);
        if (!FJsonSerializer::Serialize(ProbeReport, ProbeWriter)
            || !FFileHelper::SaveStringToFile(
                ProbeJsonText, *FPaths::Combine(Arguments.OutDirectory, TEXT("region_eval.json")),
                FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] could not write worker hash probe report."));
            return 2;
        }
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeRegionEval] worker hash probe workers=%d observed=%d samples=%lld "
                 "raw=%s reference_match=%s report=%s"),
            WorkerHashPass.Timing.Workers, WorkerHashPass.Timing.ObservedWorkerThreads,
            static_cast<long long>(WorkerHashPass.Timing.SampleCount), *ActualRawHash,
            bMatchesReference ? TEXT("yes") : TEXT("no"),
            *FPaths::Combine(Arguments.OutDirectory, TEXT("region_eval.json")));
        return bProbePassed ? 0 : 2;
    }

    // Region-eval returns before the normal Explore sampler setup. Capture only its two cold live
    // ring trials so prepared-path and multi-seed work cannot pollute the baseline attribution.
    FRegionEvalStackSamplerSession StackSamplerSession;
    if (Arguments.bSampleStacks
        && !StackSamplerSession.Start(
            Arguments.SampleStacksIntervalUs, Arguments.OutDirectory))
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeRegionEval] requested stack sampler could not be started."));
        return 2;
    }

    const int32 Seeds[] = { 1337, 7331, 19427, 30241, 41011 };
    TArray<TSharedPtr<FJsonValue>> SeedReports;
    TArray<TSharedPtr<FJsonValue>> OldTimingReports;
    TArray<TSharedPtr<FJsonValue>> PreparedTimingReports;
    TArray<float> OldFullDensities;
    TArray<float> PreparedFullDensities;
    TArray<int64> PrimarySampleIndices;
    FQuantizedComparison FullComparison;
    uint64 OldFullRawHash = 0;
    uint64 PreparedFullRawHash = 0;
    uint64 OldFullSaturatedSamples = 0;
    uint64 PreparedFullSaturatedSamples = 0;
    bool bAllSeedComparisonsPass = true;
    bool bFullDeterminismPass = true;
    int32 PrimaryTargetedSampleCount = 0;
    int32 PrimaryPassageCount = 0;
    int32 PrimaryEditChunkCount = 0;
    int32 PrimaryRecipeIndex = INDEX_NONE;
    uint32 PrimaryRecipeHash = 0;

    // Cold full-ring timings use independent transient worlds for every pass. Caches cannot be
    // warmed by the comparison leg, and the seed/layout/composer/edit payload remains identical.
    for (int32 Trial = 0; Trial < 2; ++Trial)
    {
        FRegionEvalPass Pass;
        const bool bOk = RunRegionEvalPass(
            Arguments, Seeds[0], false, false, 1.0f, true, nullptr,
            RequestedSamples, Trial == 0 && !Arguments.bSampleStacks, true, Pass, Error);
        if (!bOk)
        {
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] live full-ring trial failed: %s"), *Error);
            return 2;
        }
        CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
        if (Trial == 0)
        {
            OldFullDensities = MoveTemp(Pass.Densities);
            OldFullRawHash = Pass.Timing.RawFloatHash;
            OldFullSaturatedSamples = Pass.Timing.SaturatedSamples;
            PrimarySampleIndices = Pass.SampleIndices;
            PrimaryTargetedSampleCount = Pass.TargetedSampleCount;
            PrimaryPassageCount = Pass.PassageCount;
            PrimaryEditChunkCount = Pass.EditChunkCount;
            PrimaryRecipeIndex = Pass.RecipeIndex;
            PrimaryRecipeHash = Pass.RecipeHash;
        }
        else
        {
            bFullDeterminismPass &= Pass.Timing.RawFloatHash == OldFullRawHash;
        }
        OldTimingReports.Add(MakeShared<FJsonValueObject>(RegionEvalTimingJson(Pass, false)));
    }
    if (Arguments.bSampleStacks)
    {
        FVoxelStackSampler::FSummary StackSummary;
        if (!StackSamplerSession.Stop(StackSummary))
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] stack capture retained no live-ring worker samples."));
            return 2;
        }
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeRegionEval] live-ring stack capture registered=%llu retained=%llu "
                 "raw=%s summary=%s"),
            static_cast<unsigned long long>(StackSummary.RegisteredThreadSamples),
            static_cast<unsigned long long>(StackSummary.RetainedSamples),
            *StackSummary.RawSamplesPath, *StackSummary.SummaryPath);
    }
    if (PrimarySampleIndices.IsEmpty())
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] primary statistical sample set is empty."));
        return 2;
    }

    for (int32 Trial = 0; Trial < 2; ++Trial)
    {
        FRegionEvalPass Pass;
        const bool bOk = RunRegionEvalPass(
            Arguments, Seeds[0], true, true, 1.0f, true, nullptr,
            RequestedSamples, Trial == 0, true, Pass, Error);
        if (!bOk)
        {
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] prepared full-ring trial failed: %s"), *Error);
            return 2;
        }
        CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
        if (Trial == 0)
        {
            PreparedFullDensities = MoveTemp(Pass.Densities);
            PreparedFullRawHash = Pass.Timing.RawFloatHash;
            PreparedFullSaturatedSamples = Pass.Timing.SaturatedSamples;
            FullComparison = CompareQuantizedArrays(OldFullDensities, PreparedFullDensities);
        }
        else
        {
            bFullDeterminismPass &= Pass.Timing.RawFloatHash == PreparedFullRawHash;
        }
        PreparedTimingReports.Add(MakeShared<FJsonValueObject>(RegionEvalTimingJson(Pass, true)));
    }
    bAllSeedComparisonsPass &= FullComparison.Disagreements == 0
        && FullComparison.SignDisagreements == 0
        && OldFullSaturatedSamples == 0
        && PreparedFullSaturatedSamples == 0;

    // Statistical fixed-lattice comparisons across four additional independent seeds. The sample
    // set is a deterministic affine permutation of the entire 259^3 ring plus dense strata,
    // passage-floor, landing, carve, and fill probes.
    if (Arguments.bSampleStacks)
    {
        FRegionEvalStackSamplerSession BrickStackSamplerSession;
        if (!BrickStackSamplerSession.Start(
                Arguments.SampleStacksIntervalUs, Arguments.OutDirectory,
                TEXT("region_eval_brick_ring")))
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] brick stack sampler could not be started."));
            return 2;
        }
        FRegionEvalPass ProfiledBrickPass;
        if (!RunRegionEvalPass(
                Arguments, Seeds[0], true, true, 1.0f, true, nullptr,
                RequestedSamples, false, false, ProfiledBrickPass, Error))
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] brick attribution run failed: %s"), *Error);
            return 2;
        }
        FVoxelStackSampler::FSummary BrickStackSummary;
        if (!BrickStackSamplerSession.Stop(BrickStackSummary))
        {
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeRegionEval] brick stack capture retained no worker samples."));
            return 2;
        }
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeRegionEval] brick stack capture registered=%llu retained=%llu "
                 "raw=%s summary=%s"),
            static_cast<unsigned long long>(BrickStackSummary.RegisteredThreadSamples),
            static_cast<unsigned long long>(BrickStackSummary.RetainedSamples),
            *BrickStackSummary.RawSamplesPath, *BrickStackSummary.SummaryPath);
    }

    for (int32 SeedIndex = 1; SeedIndex < UE_ARRAY_COUNT(Seeds); ++SeedIndex)
    {
        FRegionEvalPass OldPass;
        if (!RunRegionEvalPass(
                Arguments, Seeds[SeedIndex], false, false, 1.0f, false, nullptr,
                RequestedSamples, true, true, OldPass, Error))
        {
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] seed %d live sample failed: %s"),
                Seeds[SeedIndex], *Error);
            return 2;
        }
        CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
        FRegionEvalPass NewPass;
        if (!RunRegionEvalPass(
                Arguments, Seeds[SeedIndex], true, true, 1.0f, false, &OldPass.SampleIndices,
                RequestedSamples, true, true, NewPass, Error))
        {
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] seed %d prepared sample failed: %s"),
                Seeds[SeedIndex], *Error);
            return 2;
        }
        CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
        const FQuantizedComparison Comparison = CompareQuantizedArrays(
            OldPass.Densities, NewPass.Densities, &OldPass.SampleIndices);
        bAllSeedComparisonsPass &= Comparison.Disagreements == 0
            && Comparison.SignDisagreements == 0
            && OldPass.Timing.SaturatedSamples == 0
            && NewPass.Timing.SaturatedSamples == 0;

        TSharedRef<FJsonObject> SeedJson = MakeShared<FJsonObject>();
        SeedJson->SetNumberField(TEXT("seed"), Seeds[SeedIndex]);
        SeedJson->SetNumberField(TEXT("samples"), OldPass.Timing.SampleCount);
        SeedJson->SetNumberField(TEXT("targeted_route_edit_boundary_samples"), OldPass.TargetedSampleCount);
        SeedJson->SetNumberField(TEXT("composer_recipe_index"), OldPass.RecipeIndex);
        SeedJson->SetStringField(TEXT("composer_recipe_hash"), FString::Printf(TEXT("%08x"), OldPass.RecipeHash));
        SeedJson->SetNumberField(TEXT("passage_count"), OldPass.PassageCount);
        SeedJson->SetNumberField(TEXT("edit_chunk_count"), OldPass.EditChunkCount);
        SeedJson->SetObjectField(TEXT("comparison"), RegionEvalComparisonJson(Comparison));
        SeedJson->SetObjectField(TEXT("live_candidate_visits"), RegionEvalTimingJson(OldPass, false));
        SeedJson->SetObjectField(TEXT("prepared_candidate_visits"), RegionEvalTimingJson(NewPass, true));
        SeedReports.Add(MakeShared<FJsonValueObject>(SeedJson));
    }

    // Deliberately shrink one reach, evaluate the same statistical lattice points, and require
    // the reference comparison to catch omitted room influence. The scale is scoped to this one
    // commandlet pass and every worker resets it to 1.0 afterward.
    FRegionEvalPass ShrunkPass;
    if (!RunRegionEvalPass(
            Arguments, Seeds[0], true, true, 0.50f, false, &PrimarySampleIndices,
            RequestedSamples, false, true, ShrunkPass, Error))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] deliberate reach-shrink run failed: %s"), *Error);
        return 2;
    }
    CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
    FQuantizedComparison ShrinkComparison;
    ShrinkComparison.FirstIndex = INDEX_NONE;
    for (int32 Sample = 0; Sample < ShrunkPass.Densities.Num(); ++Sample)
    {
        const int64 LatticeIndex = PrimarySampleIndices[Sample];
        bool bSaturatedOld = false, bFiniteOld = false;
        bool bSaturatedShrink = false, bFiniteShrink = false;
        const int16 QOld = VoxelForgeRegionEval::QuantizeDensity(
            OldFullDensities[static_cast<int32>(LatticeIndex)], bSaturatedOld, bFiniteOld);
        const int16 QShrink = VoxelForgeRegionEval::QuantizeDensity(
            ShrunkPass.Densities[Sample], bSaturatedShrink, bFiniteShrink);
        ShrinkComparison.MaxAbsoluteFloatDelta = FMath::Max(
            ShrinkComparison.MaxAbsoluteFloatDelta,
            FMath::Abs(static_cast<double>(OldFullDensities[static_cast<int32>(LatticeIndex)])
                - static_cast<double>(ShrunkPass.Densities[Sample])));
        if (!bFiniteOld || !bFiniteShrink || bSaturatedOld || bSaturatedShrink || QOld != QShrink)
        {
            ++ShrinkComparison.Disagreements;
            if (ShrinkComparison.FirstIndex == INDEX_NONE) ShrinkComparison.FirstIndex = LatticeIndex;
        }
        if ((QOld < 0) != (QShrink < 0)) ++ShrinkComparison.SignDisagreements;
    }

    double PreparedWallSum = 0.0;
    for (const TSharedPtr<FJsonValue>& Value : PreparedTimingReports)
    {
        const TSharedPtr<FJsonObject> Json = Value->AsObject();
        PreparedWallSum += Json->GetNumberField(TEXT("wall_seconds"));
    }
    const double PreparedMedianWall = PreparedWallSum / 2.0;
    double OldWallSum = 0.0;
    for (const TSharedPtr<FJsonValue>& Value : OldTimingReports)
    {
        OldWallSum += Value->AsObject()->GetNumberField(TEXT("wall_seconds"));
    }
    const double OldMedianWall = OldWallSum / 2.0;
    bool bSixWorkersObserved = true;
    for (const TSharedPtr<FJsonValue>& Value : OldTimingReports)
    {
        bSixWorkersObserved &= Value->AsObject()->GetNumberField(TEXT("observed_worker_threads"))
            >= VoxelForgeRegionEval::WorkerCount;
    }
    for (const TSharedPtr<FJsonValue>& Value : PreparedTimingReports)
    {
        bSixWorkersObserved &= Value->AsObject()->GetNumberField(TEXT("observed_worker_threads"))
            >= VoxelForgeRegionEval::WorkerCount;
    }
    const bool bSpeedPass = PreparedMedianWall <= 0.600 && bSixWorkersObserved;

    TSharedRef<FJsonObject> Report = MakeShared<FJsonObject>();
    Report->SetNumberField(TEXT("schema_version"), 1);
    Report->SetStringField(TEXT("route"), TEXT("editor-only explore commandlet; required Unreal composer, manager, and generator types"));
    Report->SetStringField(TEXT("evaluator"), TEXT("editor-only 8^3 region brick program; block-evaluated composer operator core and canonical per-point final-field writers; unsupported routes use counted live fallbacks"));
    Report->SetStringField(TEXT("comparison_quantization"), TEXT("signed int16; round ties away from zero; multiply density by 16; saturate outside [-2048, 2047.9375] density voxels"));
    Report->SetNumberField(TEXT("worker_count"), VoxelForgeRegionEval::WorkerCount);
    Report->SetNumberField(TEXT("ring_dimension"), VoxelForgeRegionEval::RingDimension);
    Report->SetNumberField(TEXT("ring_lattice_samples"), static_cast<double>(VoxelForgeRegionEval::RingDimension) * VoxelForgeRegionEval::RingDimension * VoxelForgeRegionEval::RingDimension);
    Report->SetNumberField(TEXT("ring_interval_span_voxels"), VoxelForgeRegionEval::RingDimension - 1);
    Report->SetNumberField(TEXT("ring_wall_p50_live_seconds"), OldMedianWall);
    Report->SetNumberField(TEXT("ring_wall_p50_prepared_seconds"), PreparedMedianWall);
    Report->SetBoolField(TEXT("speed_pass_600ms"), bSpeedPass);
    Report->SetBoolField(TEXT("all_full_ring_trials_used_six_threads"), bSixWorkersObserved);
    Report->SetBoolField(TEXT("five_seed_correctness_pass"), bAllSeedComparisonsPass);
    Report->SetBoolField(TEXT("two_run_determinism_pass"), bFullDeterminismPass);
    Report->SetStringField(TEXT("determinism_basis"), TEXT("bitwise float32 lattice hash on two independent cold worlds for live and prepared paths"));
    Report->SetObjectField(TEXT("full_ring_comparison"), RegionEvalComparisonJson(FullComparison));
    Report->SetArrayField(TEXT("live_full_ring_trials"), OldTimingReports);
    Report->SetArrayField(TEXT("prepared_full_ring_trials"), PreparedTimingReports);
    Report->SetArrayField(TEXT("additional_seed_comparisons"), SeedReports);

    TSharedRef<FJsonObject> Coverage = MakeShared<FJsonObject>();
    Coverage->SetStringField(TEXT("owner_settings"), Arguments.SettingsReference);
    Coverage->SetStringField(TEXT("owner_strate"), Arguments.StrateReference);
    Coverage->SetNumberField(TEXT("primary_seed"), Seeds[0]);
    Coverage->SetNumberField(TEXT("primary_targeted_route_edit_boundary_samples"), PrimaryTargetedSampleCount);
    Coverage->SetNumberField(TEXT("target_passages"), PrimaryPassageCount);
    Coverage->SetNumberField(TEXT("transient_edit_chunks"), PrimaryEditChunkCount);
    Coverage->SetNumberField(TEXT("composer_recipe_index"), PrimaryRecipeIndex);
    Coverage->SetStringField(TEXT("composer_recipe_hash"), FString::Printf(TEXT("%08x"), PrimaryRecipeHash));
    Coverage->SetStringField(TEXT("composer_recipe_family"), TEXT("RoomGraphSource with TunnelNetwork params; rolled by VF_RollStrateStructure"));
    Coverage->SetNumberField(TEXT("room_warp_strength_lower_bound"), 1.25);
    Coverage->SetStringField(TEXT("room_bin_reach"), TEXT("cached CullRadiusSq: shape extent + floor-relief envelope + 3x SDF blend + conservative terrain-op reach; mouth-rise reach uses center-to-mouth distance + blend"));
    Coverage->SetStringField(TEXT("tunnel_bin_reach"), TEXT("union of finalized warped-SDF and world-chain centerline bounds expanded by their influence radii, plus both conservative bounding spheres"));
    Coverage->SetStringField(TEXT("warp_coordinates"), TEXT("room bins are queried after the exact live cave warp in the same coordinate domain; tunnel bins union warped-SDF and unwarped world-chain reach"));
    Coverage->SetStringField(TEXT("tunnel_bin_unit"), TEXT("whole cached tunnel chain; per-chain segment loops remain in the exact evaluator"));
    Coverage->SetStringField(TEXT("unbinned_writers"), TEXT("passage/landing posts, disturbances, and player diff edits stay in canonical GetDensityAt tail; this is the candidate-bin ablation, not the full region compiler"));
    Coverage->SetBoolField(TEXT("route_landing_floor_probes"), PrimaryPassageCount > 0);
    Coverage->SetBoolField(TEXT("strata_top_and_bottom_boundary_sweep"), true);
    Coverage->SetBoolField(TEXT("player_carve_and_fill_edits"), true);
    Report->SetObjectField(TEXT("content_coverage"), Coverage);

    TSharedRef<FJsonObject> Shrink = MakeShared<FJsonObject>();
    Shrink->SetNumberField(TEXT("room_reach_scale"), 0.50);
    Shrink->SetBoolField(TEXT("deliberately_shrunk_bin_was_caught"), ShrinkComparison.Disagreements > 0);
    Shrink->SetNumberField(TEXT("saturated_samples"), static_cast<double>(ShrunkPass.Timing.SaturatedSamples));
    Shrink->SetNumberField(TEXT("quantized_disagreements"), static_cast<double>(ShrinkComparison.Disagreements));
    Shrink->SetNumberField(TEXT("sign_disagreements"), static_cast<double>(ShrinkComparison.SignDisagreements));
    Shrink->SetNumberField(TEXT("max_abs_float_delta"), ShrinkComparison.MaxAbsoluteFloatDelta);
    Shrink->SetNumberField(TEXT("first_disagreement_linear_index"), static_cast<double>(ShrinkComparison.FirstIndex));
    Report->SetObjectField(TEXT("deliberate_reach_shrink"), Shrink);

    const bool bPassed = bAllSeedComparisonsPass && bFullDeterminismPass
        && ShrinkComparison.Disagreements > 0
        && ShrunkPass.Timing.SaturatedSamples == 0;
    Report->SetStringField(TEXT("status"), bPassed ? TEXT("correctness_pass_speed_measured") : TEXT("correctness_failed"));
    Report->SetBoolField(TEXT("pass"), bPassed);
    Report->SetStringField(TEXT("speed_verdict"), bSpeedPass
        ? TEXT("meets 600 ms") : TEXT("misses 600 ms; candidate bins are an ablation, not a full region compiler"));
    FString JsonText;
    TSharedRef<TJsonWriter<>> Writer = TJsonWriterFactory<>::Create(&JsonText);
    if (!FJsonSerializer::Serialize(Report, Writer)
        || !FFileHelper::SaveStringToFile(
            JsonText, *FPaths::Combine(Arguments.OutDirectory, TEXT("region_eval.json")),
            FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeRegionEval] could not write region_eval.json."));
        return 2;
    }
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeRegionEval] status=%s speed600=%s live_ms=%.3f prepared_ms=%.3f "
             "full_q16_diff=%lld five_seed=%s deterministic=%s shrink_q16_diff=%lld report=%s"),
        bPassed ? TEXT("pass") : TEXT("fail"), bSpeedPass ? TEXT("yes") : TEXT("no"),
        OldMedianWall * 1000.0, PreparedMedianWall * 1000.0,
        static_cast<long long>(FullComparison.Disagreements),
        bAllSeedComparisonsPass ? TEXT("pass") : TEXT("fail"),
        bFullDeterminismPass ? TEXT("pass") : TEXT("fail"),
        static_cast<long long>(ShrinkComparison.Disagreements),
        *FPaths::Combine(Arguments.OutDirectory, TEXT("region_eval.json")));
    return bPassed ? 0 : 2;
}

class FGeneratorDensitySampler final : public IVoxelStrateDensitySampler
{
public:
    explicit FGeneratorDensitySampler(const UVoxelGenerator& InGenerator)
        : Generator(InGenerator)
    {
    }

    virtual float SampleDensity(float WorldX, float WorldY, float WorldZ) const override
    {
        return Generator.GetDensityAt(WorldX, WorldY, WorldZ);
    }

private:
    const UVoxelGenerator& Generator;
};

struct FExploreRenderFrame
{
    FString FileName;
    FString Purpose = TEXT("overview");
    FString CameraSeedSource = TEXT("player_fit");
    FVector CameraSeedPoseVoxels = FVector::ZeroVector;
    FVector CameraVoxels = FVector::ZeroVector;
    FVector TargetVoxels = FVector::ZeroVector;
    int32 HitPixels = 0;
    bool bScaleMarkerProjected = false;
    bool bFailureMarkersProjected = false;
    bool bPartial = false;
};

struct FExploreRenderOutput
{
    FString Status;
    FString RefusalReason;
    int32 Width = 0;
    int32 Height = 0;
    float FixedStepVoxels = 0.0f;
    float FixedStepMeters = 0.0f;
    int32 BisectionIterations = 0;
    float MaxDistanceVoxels = 0.0f;
    int64 EstimatedFixedDensitySamples = 0;
    int64 LegacyTwoViewEstimatedDensitySamples = 0;
    FString StepRationale;
    FString CameraSeedPolicy;
    int32 CameraSeedCount = 0;
    bool bAllCamerasPlayerFit = false;
    double MeshSeconds = 0.0;
    double RasterSeconds = 0.0;
    double FirstViewRasterSeconds = 0.0;
    double AdditionalViewRasterSeconds = 0.0;
    int32 RequestedViewpointCount = 8;
    bool bMeshComplete = false;
    double MeshAccelerationSeconds = 0.0;
    bool bTruncated = false;
    TArray<FExploreRenderFrame> Frames;
};

struct FExploreWalkOutput
{
    FString Status;
    FString RefusalReason;
    bool bHasArrival = false;
    bool bHasDeparture = false;
    int32 ArrivalPassageCount = 0;
    int32 DeparturePassageCount = 0;
    FVector ArrivalVoxels = FVector::ZeroVector;
    FVector DepartureVoxels = FVector::ZeroVector;
    FString WindowPolicy;
    FVoxelPlayerFitWalkReport Report;
    bool bOriginCheckAttempted = false;
    bool bOriginCheckAvailable = false;
    FString OriginCheckRefusalReason;
    FVoxelPlayerFitWalkReport OriginCheckReport;
    int32 ArrivalLandingRoomProbeCount = 0;
    int32 ArrivalLandingRoomPlayerFitProbeCount = 0;
    int32 ArrivalLandingRoomArrivalComponentProbeCount = 0;
    int32 DepartureLandingRoomProbeCount = 0;
    int32 DepartureLandingRoomPlayerFitProbeCount = 0;
    int32 DepartureLandingRoomArrivalComponentProbeCount = 0;
    // Captured by the one walk pass and consumed by render camera selection. These are internal
    // hand-off buffers, not a second source of truth for the field.
    FVoxelStrateSampleGrid SharedSampleGrid;
    TArray<FVector> CameraSeedPoses;
    TArray<FString> CameraSeedSources;
};

struct FExploreMeshMetrics
{
    int32 VertexCount = 0;
    int32 TriangleCount = 0;
    int32 SharedEdgeCount = 0;
    int32 DihedralSampleCount = 0;
    int32 NormalComparisonTriangleCount = 0;
    float EdgeLengthP50Meters = 0.0f;
    float EdgeLengthP99Meters = 0.0f;
    float EdgeLengthMaxMeters = 0.0f;
    float DihedralP50Degrees = 0.0f;
    float DihedralP75Degrees = 0.0f;
    float DihedralP90Degrees = 0.0f;
    float DihedralP95Degrees = 0.0f;
    float DihedralP99Degrees = 0.0f;
    float DihedralFractionOver20Degrees = 0.0f;
    float DihedralFractionOver40Degrees = 0.0f;
    float FaceNormalVsMeanVertexNormalP50Degrees = 0.0f;
    float FaceNormalVsMeanVertexNormalP90Degrees = 0.0f;
};

struct FExploreMeshEdgeKey
{
    FIntVector First = FIntVector::ZeroValue;
    FIntVector Second = FIntVector::ZeroValue;

    bool operator==(const FExploreMeshEdgeKey& Other) const
    {
        return First == Other.First && Second == Other.Second;
    }
};

FORCEINLINE uint32 GetTypeHash(const FExploreMeshEdgeKey& Key)
{
    return HashCombine(GetTypeHash(Key.First), GetTypeHash(Key.Second));
}

struct FExploreMeshEdgeIncident
{
    int32 IncidentCount = 0;
    int32 FirstTriangle = INDEX_NONE;
    int32 SecondTriangle = INDEX_NONE;
};

struct FExploreExportOutput
{
    FString Status;
    FString RefusalReason;
    FString MeshFileName;
    FString ManifestFileName;
    FIntVector RegionOrigin = FIntVector::ZeroValue;
    int32 RegionSize = 0;
    int32 MesherTileCount = 0;
    int32 MesherTilesCompleted = 0;
    int64 EstimatedWorkingBytes = 0;
    int64 WorkingMemoryCapBytes = MaxExportWorkingBytes;
    int64 MeshArrayBytes = 0;
    int64 MeshFileSizeBytes = 0;
    int32 VertexCount = 0;
    int32 TriangleCount = 0;
    FExploreMeshMetrics SurfaceMetrics;
    double MeshSeconds = 0.0;
    double MeshUsPerVoxel = 0.0;
    double MeasureSeconds = 0.0;
    double ObjWriteSeconds = 0.0;
    double ManifestSeconds = 0.0;
    double ExportWallSeconds = 0.0;
    double ExportAccountingRemainderSeconds = 0.0;
    FString GeometryHash;
    bool bTruncated = false;
};

struct FExploreDensitySliceOutput
{
    FString Status;
    FString RefusalReason;
    FString FileName;
    int32 SampleCount = 0;
    int32 FiniteSampleCount = 0;
    int32 NonFiniteSampleCount = 0;
    int32 ZeroCrossingCount = 0;
    int32 SaturatedSampleCount = 0;
    float MinDensity = 0.0f;
    float MaxDensity = 0.0f;
    float MaxAbsDensity = 0.0f;
    double Seconds = 0.0;
};

struct FExploreTunnelCoreProbeAxis
{
    FString Name;
    int32 ValidCoreCrossings = 0;
    int32 ValidFinalCrossings = 0;
    float CoreMeanCrossingVoxels = 0.0f;
    float FinalMeanCrossingVoxels = 0.0f;
    float CoreMinCrossingVoxels = 0.0f;
    float CoreMaxCrossingVoxels = 0.0f;
    float FinalMinCrossingVoxels = 0.0f;
    float FinalMaxCrossingVoxels = 0.0f;
    float CorePeriodicAmplitudeVoxels = 0.0f;
    float CorePeriodicPeriodVoxels = 0.0f;
    float FinalPeriodicAmplitudeVoxels = 0.0f;
    float FinalPeriodicPeriodVoxels = 0.0f;
    int32 CorePeriodicMeasuredSamples = 0;
    float CorePeriodicMeasuredLengthVoxels = 0.0f;
    int32 FinalPeriodicMeasuredSamples = 0;
    float FinalPeriodicMeasuredLengthVoxels = 0.0f;
    TArray<float> CoreCrossingsVoxels;
    TArray<float> FinalCrossingsVoxels;
};

struct FExploreTunnelMouthProbeAxis
{
    FString Name;
    int32 ValidCrossings = 0;
    float MeanCrossingVoxels = 0.0f;
    float MinCrossingVoxels = 0.0f;
    float MaxCrossingVoxels = 0.0f;
    float PeriodicAmplitudeVoxels = 0.0f;
    float PeriodicPeriodVoxels = 0.0f;
    int32 PeriodicMeasuredSamples = 0;
    float PeriodicMeasuredLengthVoxels = 0.0f;
    // Audit value from the core probe's local-median detrend. Mouth surfaces can carry a broad
    // room-floor bowl over the +/-2R window, so the accepted mouth value below uses a degree-six
    // slow trend while retaining this legacy value for before/after diagnosis.
    float LocalMedianPeriodicAmplitudeVoxels = 0.0f;
    float LocalMedianPeriodicPeriodVoxels = 0.0f;
    TArray<float> CrossingsVoxels;
};

struct FExploreTunnelMouthProbeEndpoint
{
    FString Name;
    uint32 RoomHash = 0;
    FVector Mouth = FVector::ZeroVector;
    float RadiusVoxels = 0.0f;
    float TunnelFloorZ = -FLT_MAX;
    float RoomFloorCrossingZ = -FLT_MAX;
    float FloorJoinDeltaVoxels = 0.0f;
    FExploreTunnelMouthProbeAxis Wall;
    FExploreTunnelMouthProbeAxis Floor;
};

struct FExploreTunnelMouthProbeOutput
{
    FString Status;
    FString RefusalReason;
    FString FileName;
    int32 EndpointCount = 0;
    int32 LateralSampleCount = 0;
    float LateralStepVoxels = 0.25f;
    float LateralWindowVoxels = 0.0f;
    int32 RoomSampleStepVoxels = 2;
    int64 RoomVolumeSampleCount = 0;
    int64 RoomAirSampleCount = 0;
    int64 CoreBottomSampleCount = 0;
    int64 FinalSolidSampleCount = 0;
    int64 CoreInducedSolidSampleCount = 0;
    float MaxWallPeriodicAmplitudeVoxels = 0.0f;
    float MaxFloorPeriodicAmplitudeVoxels = 0.0f;
    float MaxLocalMedianWallPeriodicAmplitudeVoxels = 0.0f;
    float MaxLocalMedianFloorPeriodicAmplitudeVoxels = 0.0f;
    double Seconds = 0.0;
    TArray<FExploreTunnelMouthProbeEndpoint> Endpoints;
};

struct FExploreTunnelCoreProbeOutput
{
    FString Status;
    FString RefusalReason;
    FString FileName;
    int32 TunnelIndex = INDEX_NONE;
    int32 SampleCount = 0;
    int32 CoreCenterFiniteSampleCount = 0;
    int32 CoreCenterZeroCrossingCount = 0;
    int32 FinalCenterFiniteSampleCount = 0;
    int32 FinalCenterZeroCrossingCount = 0;
    int32 FinalCenterSaturatedSampleCount = 0;
    float CoreCenterMin = 0.0f;
    float CoreCenterMax = 0.0f;
    float FinalCenterMin = 0.0f;
    float FinalCenterMax = 0.0f;
    float FinalCenterMaxAbs = 0.0f;
    float StepVoxels = 0.25f;
    float LengthVoxels = 0.0f;
    FVector AxisStart = FVector::ZeroVector;
    FVector AxisEnd = FVector::ZeroVector;
    FVector AxisDirection = FVector::ForwardVector;
    FVector WallDirection = FVector::RightVector;
    FExploreTunnelCoreProbeAxis Floor;
    FExploreTunnelCoreProbeAxis Wall;
    FExploreTunnelCoreProbeAxis Ceiling;
    FExploreTunnelMouthProbeOutput Mouth;
    double Seconds = 0.0;
};

struct FExploreProfilerComparison
{
    bool bAvailable = false;
    FString Scope;
    double ProfiledSeconds = 0.0;
    double UnprofiledSeconds = 0.0;
    double DiscrepancySeconds = 0.0;
    double DiscrepancyPercent = 0.0;
    double Ratio = 0.0;
    bool bGeometryEqual = false;
    FString ProfiledGeometryHash;
    FString UnprofiledGeometryHash;
    FString SelfCheck = TEXT("not_run");
};

struct FExploreRunOutput
{
    FExploreRenderOutput Render;
    FExploreWalkOutput Walk;
    FExploreExportOutput Export;
    FExploreDensitySliceOutput DensitySlice;
    FExploreTunnelCoreProbeOutput TunnelCoreProbe;
    double BudgetSeconds = 0.0;
    double ElapsedSeconds = 0.0;
    double WalkSeconds = 0.0;
    bool bTruncated = false;
    FString TruncatedDuring;
    TArray<FString> CompletedModes;
    VoxelDensityProfile::FSnapshot Profile;
    bool bHasProfile = false;
    FExploreProfilerComparison ProfilerComparison;
};

struct FExploreStackSamplerSession
{
    bool bStarted = false;

    ~FExploreStackSamplerSession()
    {
        Stop();
    }

    bool Start(uint32 IntervalUs, const FString& OutputDirectory)
    {
        if (bStarted)
        {
            return true;
        }
        bStarted = FVoxelStackSampler::Get().Start(
            IntervalUs, OutputDirectory, TEXT("commandlet"));
        return bStarted;
    }

    void Stop()
    {
        if (bStarted)
        {
            FVoxelStackSampler::Get().StopAndWrite();
            bStarted = false;
        }
    }
};

bool ValidateCanonicalTile(const FVoxelMeshData& MeshData, FString& OutError);
bool MeasureExploreMesh(
    const FVoxelMeshData& MeshData,
    FExploreMeshMetrics& OutMetrics,
    FString& OutError);

bool FindMouths(
    const UVoxelStrateManager& Manager,
    int32 TargetSlot,
    FVector& OutArrival,
    FVector& OutDeparture,
    int32& OutArrivalCount,
    int32& OutDepartureCount,
    const FVoxelPassage*& OutArrivalPassage,
    const FVoxelPassage*& OutDeparturePassage)
{
    OutArrival = FVector::ZeroVector;
    OutDeparture = FVector::ZeroVector;
    OutArrivalCount = 0;
    OutDepartureCount = 0;
    OutArrivalPassage = nullptr;
    OutDeparturePassage = nullptr;
    for (const FVoxelPassage& Passage : Manager.GetPassages())
    {
        if (Passage.LowerStrateIndex == TargetSlot
            && Passage.UpperStrateIndex + 1 == TargetSlot)
        {
            if (OutArrivalCount == 0)
            {
                OutArrival = Passage.LowerPoint;
                OutArrivalPassage = &Passage;
            }
            ++OutArrivalCount;
        }
        if (Passage.UpperStrateIndex == TargetSlot
            && Passage.LowerStrateIndex == TargetSlot + 1)
        {
            if (OutDepartureCount == 0)
            {
                OutDeparture = Passage.UpperPoint;
                OutDeparturePassage = &Passage;
            }
            ++OutDepartureCount;
        }
    }
    return OutArrivalCount > 0 && OutDepartureCount > 0;
}

struct FExploreCameraBasis
{
    FVector Forward = FVector::ForwardVector;
    FVector Right = FVector::RightVector;
    FVector Up = FVector::UpVector;
    float Aspect = 1.0f;
    float TanHalfFov = 1.0f;
};

bool BuildCameraBasis(
    const FVector& Position,
    const FVector& Target,
    float FieldOfViewDegrees,
    int32 Width,
    int32 Height,
    FExploreCameraBasis& OutBasis)
{
    OutBasis.Forward = (Target - Position).GetSafeNormal();
    if (OutBasis.Forward.IsNearlyZero())
    {
        return false;
    }
    OutBasis.Right = FVector::CrossProduct(OutBasis.Forward, FVector::UpVector).GetSafeNormal();
    if (OutBasis.Right.IsNearlyZero())
    {
        OutBasis.Right = FVector::CrossProduct(OutBasis.Forward, FVector::RightVector).GetSafeNormal();
    }
    OutBasis.Up = FVector::CrossProduct(OutBasis.Right, OutBasis.Forward).GetSafeNormal();
    OutBasis.Aspect = static_cast<float>(Width) / static_cast<float>(Height);
    OutBasis.TanHalfFov = FMath::Tan(FMath::DegreesToRadians(FieldOfViewDegrees * 0.5f));
    return OutBasis.Aspect > 0.0f && OutBasis.TanHalfFov > 0.0f;
}

void PutPixel(TArray<FColor>& Pixels, int32 Width, int32 Height, int32 X, int32 Y, const FColor& Color)
{
    if (X >= 0 && X < Width && Y >= 0 && Y < Height)
    {
        Pixels[X + Width * Y] = Color;
    }
}

void DrawLine(
    TArray<FColor>& Pixels,
    int32 Width,
    int32 Height,
    int32 X0,
    int32 Y0,
    int32 X1,
    int32 Y1,
    const FColor& Color)
{
    int32 DX = FMath::Abs(X1 - X0);
    const int32 SX = X0 < X1 ? 1 : -1;
    int32 DY = -FMath::Abs(Y1 - Y0);
    const int32 SY = Y0 < Y1 ? 1 : -1;
    int32 Error = DX + DY;
    for (;;)
    {
        PutPixel(Pixels, Width, Height, X0, Y0, Color);
        if (X0 == X1 && Y0 == Y1)
        {
            break;
        }
        const int32 DoubleError = 2 * Error;
        if (DoubleError >= DY)
        {
            Error += DY;
            X0 += SX;
        }
        if (DoubleError <= DX)
        {
            Error += DX;
            Y0 += SY;
        }
    }
}

bool ProjectPoint(
    const FVector& Point,
    const FVector& CameraPosition,
    const FExploreCameraBasis& Basis,
    int32 Width,
    int32 Height,
    FIntPoint& OutPixel)
{
    const FVector Relative = Point - CameraPosition;
    const float Depth = FVector::DotProduct(Relative, Basis.Forward);
    if (Depth <= KINDA_SMALL_NUMBER)
    {
        return false;
    }
    const float NdcX = FVector::DotProduct(Relative, Basis.Right)
        / (Depth * Basis.Aspect * Basis.TanHalfFov);
    const float NdcY = FVector::DotProduct(Relative, Basis.Up)
        / (Depth * Basis.TanHalfFov);
    OutPixel.X = FMath::RoundToInt((NdcX * 0.5f + 0.5f) * static_cast<float>(Width - 1));
    OutPixel.Y = FMath::RoundToInt((1.0f - (NdcY * 0.5f + 0.5f))
        * static_cast<float>(Height - 1));
    return NdcX >= -1.0f && NdcX <= 1.0f && NdcY >= -1.0f && NdcY <= 1.0f;
}

void DrawScaleMarker(
    TArray<FColor>& Pixels,
    int32 Width,
    int32 Height,
    const FVector& CameraPosition,
    const FVector& Target,
    const FExploreCameraBasis& Basis,
    bool& bOutProjected)
{
    constexpr float HumanHeightVoxels = 2.0f
        * FVoxelPlayerCapsuleConstants::HalfHeightVoxels;
    const FVector MarkerBase = FVector(
        Target.X,
        Target.Y,
        Target.Z - FVoxelPlayerCapsuleConstants::HalfHeightVoxels)
        - Basis.Right * 18.0f
        + Basis.Forward * 48.0f;
    const FVector MarkerTop = MarkerBase + FVector(0.0f, 0.0f, HumanHeightVoxels);
    FIntPoint BasePixel = FIntPoint::ZeroValue;
    FIntPoint TopPixel = FIntPoint::ZeroValue;
    bOutProjected = ProjectPoint(
        MarkerBase, CameraPosition, Basis, Width, Height, BasePixel)
        && ProjectPoint(MarkerTop, CameraPosition, Basis, Width, Height, TopPixel);
    if (!bOutProjected)
    {
        // The world-space marker is normally in frame by construction. Keep a visible fallback
        // for unusual camera/FOV overrides, while the JSON records that it was not projected.
        BasePixel = FIntPoint(12, Height - 12);
        TopPixel = FIntPoint(12, FMath::Max(12, Height - 12 - Height / 5));
    }

    const FColor MarkerColor(255, 220, 32, 255);
    DrawLine(Pixels, Width, Height, BasePixel.X, BasePixel.Y, TopPixel.X, TopPixel.Y, MarkerColor);
    const int32 TickHalfWidth = 5;
    for (const FIntPoint& Tick : { BasePixel, TopPixel })
    {
        DrawLine(
            Pixels,
            Width,
            Height,
            Tick.X - TickHalfWidth,
            Tick.Y,
            Tick.X + TickHalfWidth,
            Tick.Y,
            MarkerColor);
    }
}

bool SavePng(
    const FString& FilePath,
    const TArray<FColor>& Pixels,
    int32 Width,
    int32 Height,
    FString& OutError)
{
    IImageWrapperModule& ImageWrapperModule = FModuleManager::LoadModuleChecked<IImageWrapperModule>(
        FName(TEXT("ImageWrapper")));
    TSharedPtr<IImageWrapper> ImageWrapper = ImageWrapperModule.CreateImageWrapper(
        EImageFormat::PNG);
    if (!ImageWrapper.IsValid()
        || !ImageWrapper->SetRaw(
            Pixels.GetData(),
            static_cast<int64>(Pixels.Num()) * sizeof(FColor),
            Width,
            Height,
            ERGBFormat::BGRA,
            8))
    {
        OutError = TEXT("ImageWrapper could not accept the BGRA render buffer.");
        return false;
    }
    const TArray64<uint8>& Compressed = ImageWrapper->GetCompressed(100);
    if (!FFileHelper::SaveArrayToFile(Compressed, *FilePath))
    {
        OutError = FString::Printf(TEXT("Could not write PNG '%s'."), *FilePath);
        return false;
    }
    return true;
}

FIntVector ChooseExploreMeshOrigin(
    const FExploreArguments& Arguments,
    const FExploreWalkOutput* CameraSeedWalk,
    int32 MeshSize,
    int32 TargetMiddleWorldZ)
{
    if (Arguments.bExportTileOverride)
    {
        return FIntVector(
            Arguments.ExportTileX * CHUNK_SIZE,
            Arguments.ExportTileY * CHUNK_SIZE,
            Arguments.ExportTileZ * CHUNK_SIZE);
    }

    FVector Centre(0.0f, 0.0f, static_cast<float>(TargetMiddleWorldZ));
    if (CameraSeedWalk != nullptr && CameraSeedWalk->CameraSeedPoses.Num() > 0)
    {
        Centre = CameraSeedWalk->CameraSeedPoses[0];
    }

    const auto AlignTileOrigin = [MeshSize](float CentreCoordinate)
    {
        return FMath::FloorToInt(
            (CentreCoordinate - 0.5f * static_cast<float>(MeshSize))
                / static_cast<float>(CHUNK_SIZE))
            * CHUNK_SIZE;
    };
    return FIntVector(
        AlignTileOrigin(Centre.X),
        AlignTileOrigin(Centre.Y),
        AlignTileOrigin(Centre.Z));
}

bool AppendCanonicalMesh(
    FVoxelMeshData& Destination,
    const FVoxelMeshData& Source,
    FString& OutError)
{
    if (!ValidateCanonicalTile(Source, OutError))
    {
        return false;
    }

    const int32 VertexOffset = Destination.Vertices.Num();
    for (const int32 Index : Source.Triangles)
    {
        if (Index < 0 || Index >= Source.Vertices.Num())
        {
            OutError = TEXT("Canonical mesher returned an out-of-range triangle index.");
            return false;
        }
    }

    Destination.Vertices.Append(Source.Vertices);
    Destination.Normals.Append(Source.Normals);
    Destination.UVs.Append(Source.UVs);
    Destination.Colors.Append(Source.Colors);
    Destination.Triangles.Reserve(Destination.Triangles.Num() + Source.Triangles.Num());
    for (const int32 Index : Source.Triangles)
    {
        Destination.Triangles.Add(Index + VertexOffset);
    }
    // A multi-tile aggregate interleaves each tile's ground/cap runs. The CPU rasterizer uses
    // flat geometry and the OBJ path is material-neutral, so there is deliberately no invented
    // global ceiling run here.
    Destination.NumCeilingTriangles = 0;
    return true;
}

FString ComputeGeometryHash(const FVoxelMeshData& MeshData)
{
    return VoxelForgeGeometryHash::Compute(MeshData);
}

bool EnsureExploreMesh(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    const FExploreWalkOutput* CameraSeedWalk,
    FExploreBudget& Budget,
    FString& OutError)
{
    TRACE_CPUPROFILER_EVENT_SCOPE(VoxelForge_ExploreMesh);
    if (World.bExploreMeshBuilt)
    {
        OutError = World.ExploreMeshError;
        return World.bExploreMeshComplete;
    }

    World.bExploreMeshBuilt = true;
    World.bExploreMeshComplete = false;
    World.ExploreMeshError.Reset();
    World.ExploreMesh.Clear();
    World.ExploreMeshSize = Arguments.ExportSize;
    const int32 TilesPerAxis = Arguments.ExportSize / CHUNK_SIZE;
    World.ExploreMeshTileCount = TilesPerAxis * TilesPerAxis * TilesPerAxis;
    World.ExploreMeshTilesCompleted = 0;
    World.ExploreTileTriangleCounts.Init(0, World.ExploreMeshTileCount);
    World.ExploreTileGeometryHashes.SetNum(World.ExploreMeshTileCount);
    World.ExploreMeshOrigin = ChooseExploreMeshOrigin(
        Arguments,
        CameraSeedWalk,
        World.ExploreMeshSize,
        FMath::FloorToInt(0.5f * static_cast<float>(
            World.TargetBottomWorldZ + World.TargetTopWorldZ)));
    World.ExploreMeshSeconds = 0.0;
    World.ExploreMeshPreparationSeconds = 0.0;
    World.ExploreMeshPreTileSetupSeconds = 0.0;
    World.ExploreMeshMergeSeconds = 0.0;
    World.ExploreMeshAccountingRemainderSeconds = 0.0;
    World.ExploreMeshHashSeconds = 0.0;
    World.ExploreDensityGridSeconds = 0.0;
    World.ExploreDensityGridTotalSamples = 0;
    World.ExploreDensityGridUniqueSamples = 0;
    World.ExploreDensityGridDuplicateSamplesBefore = 0;
    World.ExploreDensityGridDuplicateSamplesAfter = 0;
    World.bExploreDensityGridReused = false;
    World.ExploreMeshTaskWorkerCount = 0;
    World.ExploreMeshTaskJobCount = 0;
    World.ExploreMeshTaskMinBatchSize = FMath::Clamp(Arguments.MeshMinBatchSize, 1, 64);
    World.ExploreMeshTaskMinSeconds = 0.0;
    World.ExploreMeshTaskMeanSeconds = 0.0;
    World.ExploreMeshTaskMaxSeconds = 0.0;
    World.ExploreMeshTaskSumSeconds = 0.0;
    World.ExploreMeshTaskWallSeconds = 0.0;
    World.ExploreMeshTaskLaunchOverheadSeconds = 0.0;
    World.Mesher->SetSharedDensityGrid(nullptr);
    World.ExploreSharedDensityGrid.Reset();

    if (Budget.ShouldStop(TEXT("mesh")))
    {
        World.ExploreMeshError = TEXT("The wall-clock budget elapsed before meshing began.");
        OutError = World.ExploreMeshError;
        return false;
    }

    // This is the same canonical UVoxelMarchingCubesMesher used by export and runtime chunk
    // generation.  Historical export deliberately omitted presentation skirts; parity opts into
    // the authored runtime settings so the requested comparison has the same mesher inputs.
    World.Mesher->bGenerateSkirts = Arguments.bGameRuntimeConfig
        ? World.Settings->bGenerateSkirts : false;
    World.Mesher->SkirtCells = Arguments.bGameRuntimeConfig
        ? World.Settings->SkirtCells : 2.0f;
    World.Mesher->LODOctaveDrop = Arguments.bGameRuntimeConfig
        ? World.Settings->LODOctaveDrop : 0;

    const double MeshStartSeconds = FPlatformTime::Seconds();
    if (Budget.ShouldStop(TEXT("mesh")))
    {
        World.ExploreMeshError = TEXT("The wall-clock budget elapsed before mesh tiles began.");
        OutError = World.ExploreMeshError;
        World.ExploreMeshSeconds = FPlatformTime::Seconds() - MeshStartSeconds;
        return false;
    }

    // Adjacent tiles ask for the same one-point-halo planes.  Build one immutable lattice for
    // the whole export when requested, then let each tile copy its local window from it.  The
    // precomputation is inside MeshStartSeconds on purpose: this is an end-to-end export number,
    // not a profiled bucket hiding the cost of producing the cache.
    const int32 CellsPerTile = CHUNK_SIZE / Arguments.ExportStep;
    const int32 PointsPerTile = CellsPerTile + 3;
    const int64 TileGridSamples = static_cast<int64>(PointsPerTile)
        * static_cast<int64>(PointsPerTile)
        * static_cast<int64>(PointsPerTile);
    const int32 SharedGridDim = Arguments.ExportSize / Arguments.ExportStep + 3;
    const int64 SharedGridSamples = static_cast<int64>(SharedGridDim)
        * static_cast<int64>(SharedGridDim)
        * static_cast<int64>(SharedGridDim);
    World.ExploreDensityGridTotalSamples = static_cast<int64>(World.ExploreMeshTileCount)
        * TileGridSamples;
    World.ExploreDensityGridUniqueSamples = SharedGridSamples;
    World.ExploreDensityGridDuplicateSamplesBefore = FMath::Max<int64>(
        0, World.ExploreDensityGridTotalSamples - SharedGridSamples);
    World.ExploreDensityGridDuplicateSamplesAfter =
        Arguments.bReuseDensityGrid ? 0 : World.ExploreDensityGridDuplicateSamplesBefore;

    const double DensityStageStartSeconds = FPlatformTime::Seconds();
    if (Arguments.bReuseDensityGrid)
    {
        const double DensityGridStartSeconds = FPlatformTime::Seconds();
        World.ExploreSharedDensityGrid.OriginVoxels = World.ExploreMeshOrigin
            - FIntVector(Arguments.ExportStep);
        World.ExploreSharedDensityGrid.Step = Arguments.ExportStep;
        World.ExploreSharedDensityGrid.Dim = SharedGridDim;
        World.ExploreSharedDensityGrid.Samples.SetNumUninitialized(
            SharedGridDim * SharedGridDim * SharedGridDim);
        std::atomic<bool> bGridWorkCancelled(false);
        const double GridWorkDeadline = Budget.StartSeconds + Budget.LimitSeconds - 0.25;
        const int32 GridTileCount = TilesPerAxis;
        ParallelFor(
            TEXT("VoxelForgeExploreDensityGrid"),
            World.ExploreMeshTileCount,
            World.ExploreMeshTaskMinBatchSize,
            [&](int32 LinearOwnerIndex)
            {
                if (bGridWorkCancelled.load(std::memory_order_relaxed)
                    || FPlatformTime::Seconds() >= GridWorkDeadline)
                {
                    bGridWorkCancelled.store(true, std::memory_order_relaxed);
                    return;
                }
                FScopedVoxelStackRegistration StackRegistration;
                const int32 GridOctaveBias = (World.Mesher->LODOctaveDrop > 0
                    && Arguments.ExportStep > 1)
                    ? World.Mesher->LODOctaveDrop
                        * (int32)FMath::FloorLog2((uint32)Arguments.ExportStep)
                    : 0;
                const int32 PreviousOctaveBias = VoxelGenLOD::GetThreadOctaveBias();
                const int32 PreviousSampleStep = VoxelGenLOD::GetThreadSampleStep();
                VoxelGenLOD::SetThreadOctaveBias(GridOctaveBias);
                VoxelGenLOD::SetThreadSampleStep(Arguments.ExportStep);
                const int32 OwnerX = LinearOwnerIndex % GridTileCount;
                const int32 OwnerY = (LinearOwnerIndex / GridTileCount) % GridTileCount;
                const int32 OwnerZ = LinearOwnerIndex / (GridTileCount * GridTileCount);
                FIntVector PreviousTileOrigin = FIntVector::ZeroValue;
                int32 IgnoredPreviousTileStep = 1;
                int32 PreviousTileCells = 0;
                VoxelGenLOD::GetThreadTileCacheWindow(
                    PreviousTileOrigin, IgnoredPreviousTileStep, PreviousTileCells);
                VoxelGenLOD::SetThreadTileContext(
                    World.ExploreMeshOrigin
                        + FIntVector(OwnerX * CHUNK_SIZE, OwnerY * CHUNK_SIZE, OwnerZ * CHUNK_SIZE),
                    CellsPerTile);
                // Partition the shared lattice into disjoint rectangular owner regions.  A
                // boundary sample belongs to exactly one owner; tile windows may read it from
                // either side.  This keeps the generator's spatial locality while guaranteeing
                // one evaluation per global lattice point.
                const auto OwnerMinGrid = [CellsPerTile](int32 Owner) -> int32
                {
                    return Owner == 0 ? 0 : 1 + Owner * CellsPerTile;
                };
                const auto OwnerMaxGrid = [CellsPerTile, SharedGridDim, GridTileCount](int32 Owner) -> int32
                {
                    return Owner == GridTileCount - 1
                        ? SharedGridDim
                        : 1 + (Owner + 1) * CellsPerTile;
                };
                const int32 GxMin = OwnerMinGrid(OwnerX);
                const int32 GxMax = OwnerMaxGrid(OwnerX);
                const int32 GyMin = OwnerMinGrid(OwnerY);
                const int32 GyMax = OwnerMaxGrid(OwnerY);
                const int32 GzMin = OwnerMinGrid(OwnerZ);
                const int32 GzMax = OwnerMaxGrid(OwnerZ);
                for (int32 Gz = GzMin; Gz < GzMax; ++Gz)
                {
                    for (int32 Gy = GyMin; Gy < GyMax; ++Gy)
                    {
                        for (int32 Gx = GxMin; Gx < GxMax; ++Gx)
                        {
                            const int32 Index = (Gz * SharedGridDim + Gy) * SharedGridDim + Gx;
                            World.ExploreSharedDensityGrid.Samples[Index] =
                                World.Generator->GetDensityAt(
                                    World.ExploreSharedDensityGrid.OriginVoxels.X + Gx * Arguments.ExportStep,
                                    World.ExploreSharedDensityGrid.OriginVoxels.Y + Gy * Arguments.ExportStep,
                                    World.ExploreSharedDensityGrid.OriginVoxels.Z + Gz * Arguments.ExportStep);
                        }
                    }
                }
                VoxelGenLOD::SetThreadOctaveBias(PreviousOctaveBias);
                VoxelGenLOD::SetThreadSampleStep(PreviousSampleStep);
                VoxelGenLOD::SetThreadTileContext(PreviousTileOrigin, PreviousTileCells);
            },
            EParallelForFlags::None);
        World.ExploreDensityGridSeconds = FPlatformTime::Seconds() - DensityGridStartSeconds;
        if (bGridWorkCancelled.load(std::memory_order_relaxed))
        {
            World.ExploreMeshError = TEXT("The wall-clock budget elapsed while building the shared density grid.");
            OutError = World.ExploreMeshError;
            World.ExploreMeshSeconds = FPlatformTime::Seconds() - MeshStartSeconds;
            return false;
        }
        World.Mesher->SetSharedDensityGrid(&World.ExploreSharedDensityGrid);
        World.bExploreDensityGridReused = true;
    }
    const double DensityStageEndSeconds = FPlatformTime::Seconds();
    World.ExploreMeshPreparationSeconds = DensityStageStartSeconds - MeshStartSeconds;

    // Generate each tile through the canonical mesher on worker threads, then append strictly in
    // Z/Y/X order. The mesher's scratch buffers and the generator's hot caches are thread-local;
    // the fixed merge order keeps the aggregate mesh and all downstream raster/export bytes
    // deterministic even though tile completion order is not.
    TArray<FVoxelMeshData> TileMeshes;
    TileMeshes.SetNum(World.ExploreMeshTileCount);
    TArray<FString> TileErrors;
    TileErrors.SetNum(World.ExploreMeshTileCount);
    TArray<uint8> TileCompleted;
    TileCompleted.Init(0, World.ExploreMeshTileCount);
    TArray<double> TileDurations;
    TileDurations.Init(0.0, World.ExploreMeshTileCount);
    TArray<double> TileStartOffsets;
    TileStartOffsets.Init(-1.0, World.ExploreMeshTileCount);
    TArray<double> TileEndOffsets;
    TileEndOffsets.Init(-1.0, World.ExploreMeshTileCount);
    TArray<uint32> TileThreadIds;
    TileThreadIds.Init(0, World.ExploreMeshTileCount);
    std::atomic<bool> bTileWorkCancelled(false);
    const double TileWorkDeadline = Budget.StartSeconds + Budget.LimitSeconds - 0.25;
    const double ParallelStartSeconds = FPlatformTime::Seconds();
    World.ExploreMeshPreTileSetupSeconds = ParallelStartSeconds - DensityStageEndSeconds;
    ParallelFor(
        TEXT("VoxelForgeExploreMeshTiles"),
        World.ExploreMeshTileCount,
        World.ExploreMeshTaskMinBatchSize,
        [&](int32 LinearTileIndex)
        {
            if (bTileWorkCancelled.load(std::memory_order_relaxed)
                || FPlatformTime::Seconds() >= TileWorkDeadline)
            {
                bTileWorkCancelled.store(true, std::memory_order_relaxed);
                return;
            }

            FScopedVoxelStackRegistration StackRegistration;
            const double TileStartSeconds = FPlatformTime::Seconds();
            TileStartOffsets[LinearTileIndex] = TileStartSeconds - ParallelStartSeconds;
            TileThreadIds[LinearTileIndex] = FPlatformTLS::GetCurrentThreadId();

            const int32 TileX = LinearTileIndex % TilesPerAxis;
            const int32 TileY = (LinearTileIndex / TilesPerAxis) % TilesPerAxis;
            const int32 TileZ = LinearTileIndex / (TilesPerAxis * TilesPerAxis);
            const FIntVector TileOrigin = World.ExploreMeshOrigin
                + FIntVector(TileX * CHUNK_SIZE, TileY * CHUNK_SIZE, TileZ * CHUNK_SIZE);
            TileMeshes[LinearTileIndex] = World.Mesher->GenerateMesh(
                TileOrigin,
                Arguments.ExportStep,
                CHUNK_SIZE / Arguments.ExportStep);

            FString TileError;
            if (!ValidateCanonicalTile(TileMeshes[LinearTileIndex], TileError))
            {
                TileErrors[LinearTileIndex] = MoveTemp(TileError);
                bTileWorkCancelled.store(true, std::memory_order_relaxed);
                const double TileEndSeconds = FPlatformTime::Seconds();
                TileEndOffsets[LinearTileIndex] = TileEndSeconds - ParallelStartSeconds;
                TileDurations[LinearTileIndex] = TileEndSeconds - TileStartSeconds;
                return;
            }
            TileCompleted[LinearTileIndex] = 1;
            const double TileEndSeconds = FPlatformTime::Seconds();
            TileEndOffsets[LinearTileIndex] = TileEndSeconds - ParallelStartSeconds;
            TileDurations[LinearTileIndex] = TileEndSeconds - TileStartSeconds;
        },
        EParallelForFlags::None);
    const double ParallelEndSeconds = FPlatformTime::Seconds();

    TArray<double> CompletedTileDurations;
    TSet<uint32> WorkerIds;
    double EarliestTileStart = 1.0e30;
    double LatestTileEnd = 0.0;
    for (int32 TileIndex = 0; TileIndex < World.ExploreMeshTileCount; ++TileIndex)
    {
        if (!TileCompleted[TileIndex])
        {
            continue;
        }
        CompletedTileDurations.Add(TileDurations[TileIndex]);
        WorkerIds.Add(TileThreadIds[TileIndex]);
        EarliestTileStart = FMath::Min(EarliestTileStart, TileStartOffsets[TileIndex]);
        LatestTileEnd = FMath::Max(LatestTileEnd, TileEndOffsets[TileIndex]);
    }
    if (CompletedTileDurations.Num() > 0)
    {
        CompletedTileDurations.Sort();
        World.ExploreMeshTaskJobCount = CompletedTileDurations.Num();
        World.ExploreMeshTaskWorkerCount = WorkerIds.Num();
        World.ExploreMeshTaskMinSeconds = CompletedTileDurations[0];
        World.ExploreMeshTaskMaxSeconds = CompletedTileDurations.Last();
        for (const double Duration : CompletedTileDurations)
        {
            World.ExploreMeshTaskSumSeconds += Duration;
        }
        World.ExploreMeshTaskMeanSeconds = World.ExploreMeshTaskSumSeconds
            / static_cast<double>(CompletedTileDurations.Num());
    }
    World.ExploreMeshTaskWallSeconds = ParallelEndSeconds - ParallelStartSeconds;
    if (EarliestTileStart < 1.0e30)
    {
        World.ExploreMeshTaskLaunchOverheadSeconds = FMath::Max(0.0, EarliestTileStart)
            + FMath::Max(0.0, World.ExploreMeshTaskWallSeconds - LatestTileEnd);
    }

    int32 CompletedTiles = 0;
    FString MeshError;
    for (; CompletedTiles < World.ExploreMeshTileCount; ++CompletedTiles)
    {
        if (!TileCompleted[CompletedTiles])
        {
            break;
        }
        if (!AppendCanonicalMesh(
                World.ExploreMesh,
                TileMeshes[CompletedTiles],
                MeshError))
        {
            World.ExploreMeshError = MeshError;
            OutError = MeshError;
            World.ExploreMeshTilesCompleted = CompletedTiles;
            World.ExploreMeshSeconds = FPlatformTime::Seconds() - MeshStartSeconds;
            return false;
        }
        World.ExploreTileTriangleCounts[CompletedTiles] =
            TileMeshes[CompletedTiles].Triangles.Num() / 3;
        World.ExploreTileGeometryHashes[CompletedTiles] =
            ComputeGeometryHash(TileMeshes[CompletedTiles]);
        World.ExploreMeshTilesCompleted = CompletedTiles + 1;
    }

    if (CompletedTiles < World.ExploreMeshTileCount)
    {
        if (!TileErrors[CompletedTiles].IsEmpty())
        {
            World.ExploreMeshError = TileErrors[CompletedTiles];
            OutError = World.ExploreMeshError;
            World.ExploreMeshSeconds = FPlatformTime::Seconds() - MeshStartSeconds;
            return false;
        }

        Budget.ShouldStop(TEXT("mesh"));
        World.ExploreMeshError = FString::Printf(
            TEXT("Mesh was truncated after %d/%d canonical tiles."),
            CompletedTiles,
            World.ExploreMeshTileCount);
        OutError = World.ExploreMeshError;
        World.ExploreMeshSeconds = FPlatformTime::Seconds() - MeshStartSeconds;
        return false;
    }

    const double MeshEndSeconds = FPlatformTime::Seconds();
    World.ExploreMeshSeconds = MeshEndSeconds - MeshStartSeconds;
    World.ExploreMeshMergeSeconds = MeshEndSeconds - ParallelEndSeconds;
    const double MeshStageSumSeconds = World.ExploreMeshPreparationSeconds
        + World.ExploreDensityGridSeconds
        + World.ExploreMeshPreTileSetupSeconds
        + World.ExploreMeshTaskWallSeconds
        + World.ExploreMeshMergeSeconds;
    World.ExploreMeshAccountingRemainderSeconds =
        World.ExploreMeshSeconds - MeshStageSumSeconds;
    World.bExploreMeshComplete = true;
    const double GeometryHashStartSeconds = FPlatformTime::Seconds();
    World.ExploreGeometryHash = ComputeGeometryHash(World.ExploreMesh);
    World.ExploreMeshHashSeconds = FPlatformTime::Seconds() - GeometryHashStartSeconds;
    OutError.Reset();
    return true;
}

float ExploreAxisValue(const FVector& Value, int32 Axis)
{
    switch (Axis)
    {
    case 1: return Value.Y;
    case 2: return Value.Z;
    default: return Value.X;
    }
}

FVector ExploreTriangleMin(const FVector& A, const FVector& B, const FVector& C)
{
    return FVector(
        FMath::Min3(A.X, B.X, C.X),
        FMath::Min3(A.Y, B.Y, C.Y),
        FMath::Min3(A.Z, B.Z, C.Z));
}

FVector ExploreTriangleMax(const FVector& A, const FVector& B, const FVector& C)
{
    return FVector(
        FMath::Max3(A.X, B.X, C.X),
        FMath::Max3(A.Y, B.Y, C.Y),
        FMath::Max3(A.Z, B.Z, C.Z));
}

bool EnsureExploreAcceleration(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    FExploreBudget& Budget,
    FString& OutError)
{
    if (World.bExploreAccelerationBuilt)
    {
        OutError.Reset();
        return true;
    }

    World.ExploreTriangles.Reset();
    World.ExploreTriangleOrder.Reset();
    World.ExploreBvhNodes.Reset();
    World.ExploreBvhRoot = INDEX_NONE;
    World.ExploreAccelerationSeconds = 0.0;
    const double AccelerationStartSeconds = FPlatformTime::Seconds();

    if (!World.bExploreMeshComplete)
    {
        OutError = TEXT("Cannot build mesh acceleration before the canonical mesh is complete.");
        return false;
    }
    if (Budget.ShouldStop(TEXT("mesh-acceleration")))
    {
        OutError = TEXT("The wall-clock budget elapsed before mesh acceleration began.");
        return false;
    }

    const FVoxelMeshData& Mesh = World.ExploreMesh;
    if (Mesh.Triangles.Num() % 3 != 0)
    {
        OutError = TEXT("Canonical mesh triangle index data is not divisible by three.");
        return false;
    }

    World.ExploreTriangles.Reserve(Mesh.Triangles.Num() / 3);
    for (int32 TriangleIndex = 0;
         TriangleIndex + 2 < Mesh.Triangles.Num();
         TriangleIndex += 3)
    {
        if ((TriangleIndex & 16383) == 0
            && Budget.ShouldStop(TEXT("mesh-acceleration")))
        {
            OutError = TEXT("Mesh acceleration was truncated before its triangle cache completed.");
            World.ExploreTriangles.Reset();
            return false;
        }

        const int32 IndexA = Mesh.Triangles[TriangleIndex];
        const int32 IndexB = Mesh.Triangles[TriangleIndex + 1];
        const int32 IndexC = Mesh.Triangles[TriangleIndex + 2];
        if (!Mesh.Vertices.IsValidIndex(IndexA)
            || !Mesh.Vertices.IsValidIndex(IndexB)
            || !Mesh.Vertices.IsValidIndex(IndexC))
        {
            OutError = TEXT("Canonical mesh acceleration saw an out-of-range triangle index.");
            World.ExploreTriangles.Reset();
            return false;
        }

        const FVector A = Mesh.Vertices[IndexA] / VOXEL_SIZE;
        const FVector B = Mesh.Vertices[IndexB] / VOXEL_SIZE;
        const FVector C = Mesh.Vertices[IndexC] / VOXEL_SIZE;
        if (!FMath::IsFinite(A.X) || !FMath::IsFinite(A.Y) || !FMath::IsFinite(A.Z)
            || !FMath::IsFinite(B.X) || !FMath::IsFinite(B.Y) || !FMath::IsFinite(B.Z)
            || !FMath::IsFinite(C.X) || !FMath::IsFinite(C.Y) || !FMath::IsFinite(C.Z))
        {
            OutError = TEXT("Canonical mesh acceleration saw a non-finite vertex.");
            World.ExploreTriangles.Reset();
            return false;
        }

        const FVector Cross = FVector::CrossProduct(B - A, C - A);
        if (Cross.SizeSquared() <= SMALL_NUMBER)
        {
            // Degenerate canonical triangles have no raster contribution. Keep them out of the
            // acceleration structure without changing the source mesh or its export semantics.
            continue;
        }

        FExploreMeshTriangle& Triangle = World.ExploreTriangles.AddDefaulted_GetRef();
        Triangle.A = A;
        Triangle.B = B;
        Triangle.C = C;
        Triangle.NormalA = Mesh.Normals[IndexA].GetSafeNormal();
        Triangle.NormalB = Mesh.Normals[IndexB].GetSafeNormal();
        Triangle.NormalC = Mesh.Normals[IndexC].GetSafeNormal();
        Triangle.Min = ExploreTriangleMin(A, B, C);
        Triangle.Max = ExploreTriangleMax(A, B, C);
        Triangle.Centre = (A + B + C) / 3.0f;
        Triangle.Normal = Cross.GetSafeNormal();
    }

    if (World.ExploreTriangles.Num() == 0)
    {
        // A valid empty mesh is still a complete mesh render: every pixel remains the explicit
        // background colour. The root sentinel lets the rasterizer handle this deterministically.
        World.ExploreAccelerationSeconds = FPlatformTime::Seconds() - AccelerationStartSeconds;
        World.bExploreAccelerationBuilt = true;
        OutError.Reset();
        return true;
    }

    World.ExploreTriangleOrder.SetNumUninitialized(World.ExploreTriangles.Num());
    for (int32 TriangleIndex = 0;
         TriangleIndex < World.ExploreTriangleOrder.Num();
         ++TriangleIndex)
    {
        World.ExploreTriangleOrder[TriangleIndex] = TriangleIndex;
    }

    World.ExploreBvhNodes.Reserve(World.ExploreTriangles.Num() / 4 + 2);
    bool bBuildFailed = false;
    TFunction<int32(int32, int32)> BuildNode;
    BuildNode = [&](int32 Start, int32 Count) -> int32
    {
        if (bBuildFailed || Count <= 0)
        {
            return INDEX_NONE;
        }
        if (Budget.ShouldStop(TEXT("mesh-acceleration")))
        {
            bBuildFailed = true;
            return INDEX_NONE;
        }

        const int32 NodeIndex = World.ExploreBvhNodes.AddDefaulted();
        FExploreMeshBvhNode Node;
        Node.Min = FVector(FLT_MAX, FLT_MAX, FLT_MAX);
        Node.Max = FVector(-FLT_MAX, -FLT_MAX, -FLT_MAX);
        FVector CentroidMin = FVector(FLT_MAX, FLT_MAX, FLT_MAX);
        FVector CentroidMax = FVector(-FLT_MAX, -FLT_MAX, -FLT_MAX);
        for (int32 Offset = 0; Offset < Count; ++Offset)
        {
            const int32 TriangleIndex = World.ExploreTriangleOrder[Start + Offset];
            const FExploreMeshTriangle& Triangle = World.ExploreTriangles[TriangleIndex];
            Node.Min.X = FMath::Min(Node.Min.X, Triangle.Min.X);
            Node.Min.Y = FMath::Min(Node.Min.Y, Triangle.Min.Y);
            Node.Min.Z = FMath::Min(Node.Min.Z, Triangle.Min.Z);
            Node.Max.X = FMath::Max(Node.Max.X, Triangle.Max.X);
            Node.Max.Y = FMath::Max(Node.Max.Y, Triangle.Max.Y);
            Node.Max.Z = FMath::Max(Node.Max.Z, Triangle.Max.Z);
            CentroidMin.X = FMath::Min(CentroidMin.X, Triangle.Centre.X);
            CentroidMin.Y = FMath::Min(CentroidMin.Y, Triangle.Centre.Y);
            CentroidMin.Z = FMath::Min(CentroidMin.Z, Triangle.Centre.Z);
            CentroidMax.X = FMath::Max(CentroidMax.X, Triangle.Centre.X);
            CentroidMax.Y = FMath::Max(CentroidMax.Y, Triangle.Centre.Y);
            CentroidMax.Z = FMath::Max(CentroidMax.Z, Triangle.Centre.Z);
        }

        constexpr int32 LeafTriangleCount = 8;
        if (Count <= LeafTriangleCount)
        {
            Node.FirstTriangle = Start;
            Node.TriangleCount = Count;
            World.ExploreBvhNodes[NodeIndex] = Node;
            return NodeIndex;
        }

        const FVector CentroidExtent = CentroidMax - CentroidMin;
        int32 SplitAxis = 0;
        if (CentroidExtent.Y > CentroidExtent.X
            && CentroidExtent.Y >= CentroidExtent.Z)
        {
            SplitAxis = 1;
        }
        else if (CentroidExtent.Z > CentroidExtent.X
            && CentroidExtent.Z > CentroidExtent.Y)
        {
            SplitAxis = 2;
        }

        int32* OrderBegin = World.ExploreTriangleOrder.GetData() + Start;
        int32* OrderEnd = OrderBegin + Count;
        std::sort(
            OrderBegin,
            OrderEnd,
            [&](int32 LeftIndex, int32 RightIndex)
            {
                const float LeftValue = ExploreAxisValue(
                    World.ExploreTriangles[LeftIndex].Centre, SplitAxis);
                const float RightValue = ExploreAxisValue(
                    World.ExploreTriangles[RightIndex].Centre, SplitAxis);
                if (LeftValue != RightValue)
                {
                    return LeftValue < RightValue;
                }
                return LeftIndex < RightIndex;
            });

        const int32 LeftCount = Count / 2;
        const int32 RightCount = Count - LeftCount;
        const int32 LeftNode = BuildNode(Start, LeftCount);
        const int32 RightNode = BuildNode(Start + LeftCount, RightCount);
        if (LeftNode == INDEX_NONE || RightNode == INDEX_NONE)
        {
            bBuildFailed = true;
            return INDEX_NONE;
        }

        Node.Left = LeftNode;
        Node.Right = RightNode;
        World.ExploreBvhNodes[NodeIndex] = Node;
        return NodeIndex;
    };

    World.ExploreBvhRoot = BuildNode(0, World.ExploreTriangles.Num());
    if (bBuildFailed || World.ExploreBvhRoot == INDEX_NONE || Budget.bTruncated)
    {
        World.ExploreTriangles.Reset();
        World.ExploreTriangleOrder.Reset();
        World.ExploreBvhNodes.Reset();
        World.ExploreBvhRoot = INDEX_NONE;
        OutError = TEXT("Mesh acceleration was truncated before its BVH completed.");
        return false;
    }

    World.ExploreAccelerationSeconds = FPlatformTime::Seconds() - AccelerationStartSeconds;
    World.bExploreAccelerationBuilt = true;
    OutError.Reset();
    return true;
}

bool ExploreRayAabb(
    const FVector& Origin,
    const FVector& Direction,
    const FVector& BoundsMin,
    const FVector& BoundsMax,
    float MaxDistance,
    float& OutNear)
{
    float NearDistance = 0.0f;
    float FarDistance = MaxDistance;
    for (int32 Axis = 0; Axis < 3; ++Axis)
    {
        const float OriginComponent = ExploreAxisValue(Origin, Axis);
        const float DirectionComponent = ExploreAxisValue(Direction, Axis);
        const float MinComponent = ExploreAxisValue(BoundsMin, Axis);
        const float MaxComponent = ExploreAxisValue(BoundsMax, Axis);
        if (FMath::Abs(DirectionComponent) <= KINDA_SMALL_NUMBER)
        {
            if (OriginComponent < MinComponent || OriginComponent > MaxComponent)
            {
                return false;
            }
            continue;
        }

        const float InverseDirection = 1.0f / DirectionComponent;
        float AxisNear = (MinComponent - OriginComponent) * InverseDirection;
        float AxisFar = (MaxComponent - OriginComponent) * InverseDirection;
        if (AxisNear > AxisFar)
        {
            Swap(AxisNear, AxisFar);
        }
        NearDistance = FMath::Max(NearDistance, AxisNear);
        FarDistance = FMath::Min(FarDistance, AxisFar);
        if (NearDistance > FarDistance)
        {
            return false;
        }
    }

    OutNear = NearDistance;
    return true;
}

bool ExploreRayTriangle(
    const FVector& Origin,
    const FVector& Direction,
    const FExploreMeshTriangle& Triangle,
    float MaxDistance,
    float& OutDistance,
    float& OutU,
    float& OutV)
{
    const FVector Edge1 = Triangle.B - Triangle.A;
    const FVector Edge2 = Triangle.C - Triangle.A;
    const FVector Perpendicular = FVector::CrossProduct(Direction, Edge2);
    const float Determinant = FVector::DotProduct(Edge1, Perpendicular);
    if (FMath::Abs(Determinant) <= KINDA_SMALL_NUMBER)
    {
        return false;
    }

    const float InverseDeterminant = 1.0f / Determinant;
    const FVector ToOrigin = Origin - Triangle.A;
    const float U = FVector::DotProduct(ToOrigin, Perpendicular) * InverseDeterminant;
    if (U < 0.0f || U > 1.0f)
    {
        return false;
    }

    const FVector CrossOrigin = FVector::CrossProduct(ToOrigin, Edge1);
    const float V = FVector::DotProduct(Direction, CrossOrigin) * InverseDeterminant;
    if (V < 0.0f || U + V > 1.0f)
    {
        return false;
    }

    const float Distance = FVector::DotProduct(Edge2, CrossOrigin) * InverseDeterminant;
    if (Distance <= 0.01f || Distance >= MaxDistance)
    {
        return false;
    }
    OutDistance = Distance;
    OutU = U;
    OutV = V;
    return true;
}

bool RasterizeExploreMesh(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    const FVector& CameraPosition,
    const FVector& Target,
    FExploreBudget& Budget,
    TArray<FColor>& OutPixels,
    int32& OutHitPixels,
    bool& bOutTruncated)
{
    OutPixels.Init(FColor(12, 18, 28, 255), Arguments.RenderWidth * Arguments.RenderHeight);
    OutHitPixels = 0;
    bOutTruncated = false;

    if (!World.bExploreAccelerationBuilt)
    {
        FString AccelerationError;
        if (!EnsureExploreAcceleration(Arguments, World, Budget, AccelerationError))
        {
            if (Budget.bTruncated)
            {
                bOutTruncated = true;
                return true;
            }
            return false;
        }
    }

    FExploreCameraBasis Basis;
    if (!BuildCameraBasis(
            CameraPosition,
            Target,
            70.0f,
            Arguments.RenderWidth,
            Arguments.RenderHeight,
            Basis))
    {
        return false;
    }

    const FVector KeyLightDirection = FVector(-0.35f, -0.45f, 0.82f).GetSafeNormal();
    const FVector FillLightDirection = FVector(0.65f, 0.30f, 0.70f).GetSafeNormal();
    constexpr float AmbientFill = 0.62f;
    constexpr float KeyLightStrength = 0.50f;
    constexpr float FillLightStrength = 0.24f;

    for (int32 PixelY = 0; PixelY < Arguments.RenderHeight; ++PixelY)
    {
        if (Budget.ShouldStop(TEXT("raster")))
        {
            bOutTruncated = true;
            return true;
        }

        for (int32 PixelX = 0; PixelX < Arguments.RenderWidth; ++PixelX)
        {
            const float NormalizedX = (2.0f * (static_cast<float>(PixelX) + 0.5f)
                / static_cast<float>(Arguments.RenderWidth)) - 1.0f;
            const float NormalizedY = 1.0f - (2.0f * (static_cast<float>(PixelY) + 0.5f)
                / static_cast<float>(Arguments.RenderHeight));
            const FVector Direction = (
                Basis.Forward
                + Basis.Right * (NormalizedX * Basis.Aspect * Basis.TanHalfFov)
                + Basis.Up * (NormalizedY * Basis.TanHalfFov)).GetSafeNormal();

            float ClosestDistance = Arguments.RenderMaxDistanceVoxels;
            int32 ClosestTriangleIndex = INDEX_NONE;
            float ClosestU = 0.0f;
            float ClosestV = 0.0f;
            int32 NodeStack[256];
            int32 StackCount = 0;
            if (World.ExploreBvhRoot != INDEX_NONE)
            {
                NodeStack[StackCount++] = World.ExploreBvhRoot;
            }

            while (StackCount > 0)
            {
                const int32 NodeIndex = NodeStack[--StackCount];
                if (!World.ExploreBvhNodes.IsValidIndex(NodeIndex))
                {
                    continue;
                }

                const FExploreMeshBvhNode& Node = World.ExploreBvhNodes[NodeIndex];
                float NodeNear = 0.0f;
                if (!ExploreRayAabb(
                        CameraPosition,
                        Direction,
                        Node.Min,
                        Node.Max,
                        ClosestDistance,
                        NodeNear))
                {
                    continue;
                }

                if (Node.IsLeaf())
                {
                    for (int32 Offset = 0; Offset < Node.TriangleCount; ++Offset)
                    {
                        const int32 OrderIndex = Node.FirstTriangle + Offset;
                        if (!World.ExploreTriangleOrder.IsValidIndex(OrderIndex))
                        {
                            continue;
                        }
                        const int32 TriangleIndex = World.ExploreTriangleOrder[OrderIndex];
                        if (!World.ExploreTriangles.IsValidIndex(TriangleIndex))
                        {
                            continue;
                        }
                        float TriangleDistance = 0.0f;
                        float TriangleU = 0.0f;
                        float TriangleV = 0.0f;
                        if (ExploreRayTriangle(
                                CameraPosition,
                                Direction,
                                World.ExploreTriangles[TriangleIndex],
                                ClosestDistance,
                                TriangleDistance,
                                TriangleU,
                                TriangleV))
                        {
                            ClosestDistance = TriangleDistance;
                            ClosestTriangleIndex = TriangleIndex;
                            ClosestU = TriangleU;
                            ClosestV = TriangleV;
                        }
                    }
                    continue;
                }

                const int32 LeftNodeIndex = Node.Left;
                const int32 RightNodeIndex = Node.Right;
                float LeftNear = 0.0f;
                float RightNear = 0.0f;
                const bool bHitLeft = World.ExploreBvhNodes.IsValidIndex(LeftNodeIndex)
                    && ExploreRayAabb(
                        CameraPosition,
                        Direction,
                        World.ExploreBvhNodes[LeftNodeIndex].Min,
                        World.ExploreBvhNodes[LeftNodeIndex].Max,
                        ClosestDistance,
                        LeftNear);
                const bool bHitRight = World.ExploreBvhNodes.IsValidIndex(RightNodeIndex)
                    && ExploreRayAabb(
                        CameraPosition,
                        Direction,
                        World.ExploreBvhNodes[RightNodeIndex].Min,
                        World.ExploreBvhNodes[RightNodeIndex].Max,
                        ClosestDistance,
                        RightNear);
                if (bHitLeft && bHitRight)
                {
                    if (LeftNear < RightNear)
                    {
                        if (StackCount + 2 <= UE_ARRAY_COUNT(NodeStack))
                        {
                            NodeStack[StackCount++] = RightNodeIndex;
                            NodeStack[StackCount++] = LeftNodeIndex;
                        }
                    }
                    else if (StackCount + 2 <= UE_ARRAY_COUNT(NodeStack))
                    {
                        NodeStack[StackCount++] = LeftNodeIndex;
                        NodeStack[StackCount++] = RightNodeIndex;
                    }
                }
                else if (bHitLeft && StackCount < UE_ARRAY_COUNT(NodeStack))
                {
                    NodeStack[StackCount++] = LeftNodeIndex;
                }
                else if (bHitRight && StackCount < UE_ARRAY_COUNT(NodeStack))
                {
                    NodeStack[StackCount++] = RightNodeIndex;
                }
            }

            if (ClosestTriangleIndex == INDEX_NONE)
            {
                continue;
            }

            const FExploreMeshTriangle& Triangle = World.ExploreTriangles[ClosestTriangleIndex];
            FVector ShadingNormal = (
                Triangle.NormalA * (1.0f - ClosestU - ClosestV)
                + Triangle.NormalB * ClosestU
                + Triangle.NormalC * ClosestV).GetSafeNormal();
            if (ShadingNormal.IsNearlyZero())
            {
                // The canonical mesher supplies non-zero gradient normals. Keep a defensive
                // fallback for malformed mesh data without reintroducing camera-facing flips.
                ShadingNormal = Triangle.Normal;
            }
            const float Key = FMath::Max(
                0.0f, FVector::DotProduct(ShadingNormal, KeyLightDirection));
            const float Fill = FMath::Max(
                0.0f, FVector::DotProduct(ShadingNormal, FillLightDirection));
            const float Brightness = FMath::Clamp(
                AmbientFill + KeyLightStrength * Key + FillLightStrength * Fill,
                0.0f,
                1.25f);
            const int32 PixelIndex = PixelX + Arguments.RenderWidth * PixelY;
            OutPixels[PixelIndex] = FColor(
                static_cast<uint8>(FMath::Clamp(100.0f * Brightness, 0.0f, 255.0f)),
                static_cast<uint8>(FMath::Clamp(128.0f * Brightness, 0.0f, 255.0f)),
                static_cast<uint8>(FMath::Clamp(160.0f * Brightness, 0.0f, 255.0f)),
                255);
            ++OutHitPixels;
        }
    }
    return true;
}

bool RunRender(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    const FExploreWalkOutput& CameraSeedWalk,
    FExploreRenderOutput& OutOutput,
    FExploreBudget& Budget)
{
    OutOutput = FExploreRenderOutput();
    OutOutput.Width = Arguments.RenderWidth;
    OutOutput.Height = Arguments.RenderHeight;
    OutOutput.FixedStepVoxels = Arguments.RenderStepVoxels;
    OutOutput.FixedStepMeters = Arguments.RenderStepVoxels
        * FVoxelPlayerCapsuleConstants::VoxelSizeMeters;
    OutOutput.BisectionIterations = 0;
    OutOutput.MaxDistanceVoxels = Arguments.RenderMaxDistanceVoxels;
    OutOutput.EstimatedFixedDensitySamples = 0;
    OutOutput.LegacyTwoViewEstimatedDensitySamples = static_cast<int64>(Arguments.RenderWidth)
        * static_cast<int64>(Arguments.RenderHeight)
        * 3ll
        * static_cast<int64>(FMath::Max(
            1,
            FMath::CeilToInt(
                Arguments.RenderMaxDistanceVoxels / Arguments.RenderStepVoxels)))
        * 2ll;
    OutOutput.RequestedViewpointCount = 8;
    OutOutput.StepRationale = TEXT(
        "The renderer meshes the bounded region once with UVoxelMarchingCubesMesher, then CPU "
        "rasterises its canonical triangles through a deterministic BVH-assisted depth pass. "
        "-renderstep is retained only for legacy invocation compatibility; no render pixel samples "
        "the density field.");

    OutOutput.CameraSeedPolicy = TEXT(
        "Eight deterministic viewpoints are selected from the one shared player-fit mask. Their "
        "eye-height origins are density-checked, and their azimuths are rotated in fixed 45-degree "
        "increments so every image is from inside walkable space.");

    FString MeshError;
    if (!EnsureExploreMesh(Arguments, World, &CameraSeedWalk, Budget, MeshError))
    {
        OutOutput.MeshSeconds = World.ExploreMeshSeconds;
        OutOutput.bMeshComplete = World.bExploreMeshComplete;
        if (Budget.bTruncated)
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.bTruncated = true;
            OutOutput.RefusalReason = MeshError;
        }
        else
        {
            OutOutput.Status = TEXT("error");
            OutOutput.RefusalReason = MeshError;
        }
        return false;
    }
    OutOutput.MeshSeconds = World.ExploreMeshSeconds;
    OutOutput.bMeshComplete = true;
    FString AccelerationError;
    if (!EnsureExploreAcceleration(Arguments, World, Budget, AccelerationError))
    {
        OutOutput.MeshAccelerationSeconds = World.ExploreAccelerationSeconds;
        if (Budget.bTruncated)
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.bTruncated = true;
            OutOutput.RefusalReason = AccelerationError;
        }
        else
        {
            OutOutput.Status = TEXT("error");
            OutOutput.RefusalReason = AccelerationError;
        }
        return false;
    }
    OutOutput.MeshAccelerationSeconds = World.ExploreAccelerationSeconds;
    const double RasterStartSeconds = FPlatformTime::Seconds();

    TArray<TPair<FVector, FString>, TInlineAllocator<8>> CameraSeeds;
    const auto AddCameraSeed = [&](bool bAvailable, const FVector& Position, const TCHAR* Source)
    {
        if (!bAvailable
            || !FMath::IsFinite(Position.X)
            || !FMath::IsFinite(Position.Y)
            || !FMath::IsFinite(Position.Z))
        {
            return;
        }

        // The walk mask is authoritative, but this guard catches stale/corrupt report data before
        // a render can silently start inside rock.
        const float Density = World.Generator->GetDensityAt(Position.X, Position.Y, Position.Z);
        if (!FMath::IsFinite(Density) || !(Density > 0.0f))
        {
            return;
        }
        for (const TPair<FVector, FString>& Existing : CameraSeeds)
        {
            if (Existing.Key.Equals(Position, 0.001f))
            {
                return;
            }
        }
        CameraSeeds.Emplace(Position, FString(Source));
    };

    if (Arguments.bRenderCameraOverride)
    {
        AddCameraSeed(true, Arguments.RenderCamera, TEXT("render_camera_override"));
    }

    for (int32 SeedIndex = 0; SeedIndex < CameraSeedWalk.CameraSeedPoses.Num(); ++SeedIndex)
    {
        const FString Source = CameraSeedWalk.CameraSeedSources.IsValidIndex(SeedIndex)
            ? CameraSeedWalk.CameraSeedSources[SeedIndex]
            : FString::Printf(TEXT("player_fit_%02d"), SeedIndex);
        AddCameraSeed(
            true,
            CameraSeedWalk.CameraSeedPoses[SeedIndex],
            *Source);
        if (CameraSeeds.Num() >= OutOutput.RequestedViewpointCount)
        {
            break;
        }
    }

    if (CameraSeeds.Num() == 0)
    {
        OutOutput.Status = TEXT("refused");
        OutOutput.RefusalReason = TEXT(
            "The player-fit seed pass produced no density-positive pose; refusing an inside-rock camera.");
        return false;
    }

    // A small room can contain fewer than eight distinct lattice cells. Reusing the same valid
    // player-fit origin with another deterministic angle is still a valid viewpoint and keeps
    // the contract (all camera origins are inside walkable space) without fabricating positions.
    while (CameraSeeds.Num() < OutOutput.RequestedViewpointCount)
    {
        const TPair<FVector, FString>& Anchor = CameraSeeds[0];
        CameraSeeds.Emplace(
            Anchor.Key,
            FString::Printf(TEXT("%s_angle_%02d"), *Anchor.Value, CameraSeeds.Num()));
    }

    OutOutput.CameraSeedCount = CameraSeeds.Num();
    OutOutput.bAllCamerasPlayerFit = true;
    FVector RouteFocus = FVector::ZeroVector;
    int32 RouteFocusCount = 0;
    if (Arguments.bRenderTargetOverride)
    {
        RouteFocus = Arguments.RenderTarget;
        RouteFocusCount = 1;
    }
    else if (CameraSeedWalk.bHasArrival)
    {
        RouteFocus += CameraSeedWalk.ArrivalVoxels;
        ++RouteFocusCount;
    }
    if (CameraSeedWalk.bHasDeparture)
    {
        RouteFocus += CameraSeedWalk.DepartureVoxels;
        ++RouteFocusCount;
    }
    if (RouteFocusCount > 0)
    {
        RouteFocus /= static_cast<float>(RouteFocusCount);
    }
    else
    {
        RouteFocus = CameraSeeds[0].Key;
    }

    for (int32 ViewIndex = 0; ViewIndex < CameraSeeds.Num(); ++ViewIndex)
    {
        if (Budget.ShouldStop(TEXT("render")))
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.bTruncated = true;
            OutOutput.RefusalReason = TEXT("The wall-clock budget stopped viewpoint generation.");
            return false;
        }

        const FVector CameraSeedPose = CameraSeeds[ViewIndex].Key;
        const FVector CameraPosition = CameraSeedPose
            + FVector::UpVector * (FVoxelPlayerCapsuleConstants::HalfHeightVoxels - 0.5f);
        const float CameraDensity = World.Generator->GetDensityAt(
            CameraPosition.X, CameraPosition.Y, CameraPosition.Z);
        if (!FMath::IsFinite(CameraDensity) || !(CameraDensity > 0.0f))
        {
            OutOutput.Status = TEXT("refused");
            OutOutput.RefusalReason = TEXT(
                "The eye-height offset of a player-fit camera entered solid density.");
            return false;
        }
        FVector LookDirection = RouteFocus - CameraPosition;
        LookDirection.Z = 0.0f;
        LookDirection.Normalize();
        if (LookDirection.IsNearlyZero())
        {
            LookDirection = FVector(
                ViewIndex == 1 ? -0.6f : 0.8f,
                ViewIndex == 2 ? 0.7f : -0.4f,
                0.18f).GetSafeNormal();
        }
        // Keep the camera at the fitted pose while changing the azimuth for each viewpoint.
        LookDirection = LookDirection.RotateAngleAxis(
            45.0f * static_cast<float>(ViewIndex),
            FVector::UpVector).GetSafeNormal();
        const FVector Target = CameraPosition + LookDirection * 96.0f + FVector::UpVector * 8.0f;

        const double ViewStartSeconds = FPlatformTime::Seconds();
        TArray<FColor> Pixels;
        int32 HitPixels = 0;
        bool bRasterTruncated = false;
        if (!RasterizeExploreMesh(
                Arguments,
                World,
                CameraPosition,
                Target,
                Budget,
                Pixels,
                HitPixels,
                bRasterTruncated))
        {
            OutOutput.Status = TEXT("error");
            OutOutput.RefusalReason = TEXT("Could not construct a mesh raster camera.");
            return false;
        }

        FExploreCameraBasis Basis;
        if (!BuildCameraBasis(
                CameraPosition,
                Target,
                70.0f,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                Basis))
        {
            OutOutput.Status = TEXT("error");
            OutOutput.RefusalReason = TEXT("Could not construct a render camera basis.");
            return false;
        }

        bool bScaleMarkerProjected = false;
        DrawScaleMarker(
            Pixels,
            Arguments.RenderWidth,
            Arguments.RenderHeight,
            CameraPosition,
            Target,
            Basis,
            bScaleMarkerProjected);

        FExploreRenderFrame& Frame = OutOutput.Frames.AddDefaulted_GetRef();
        Frame.FileName = FString::Printf(TEXT("render_%02d.png"), ViewIndex);
        Frame.Purpose = CameraSeeds[ViewIndex].Value;
        Frame.CameraSeedSource = CameraSeeds[ViewIndex].Value;
        Frame.CameraSeedPoseVoxels = CameraSeedPose;
        Frame.CameraVoxels = CameraPosition;
        Frame.TargetVoxels = Target;
        Frame.HitPixels = HitPixels;
        Frame.bScaleMarkerProjected = bScaleMarkerProjected;
        Frame.bPartial = bRasterTruncated;

        FString Error;
        if (!SavePng(
                FPaths::Combine(Arguments.OutDirectory, Frame.FileName),
                Pixels,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                Error))
        {
            OutOutput.Status = TEXT("error");
            OutOutput.RefusalReason = Error;
            return false;
        }

        const double ViewSeconds = FPlatformTime::Seconds() - ViewStartSeconds;
        if (ViewIndex == 0)
        {
            OutOutput.FirstViewRasterSeconds = ViewSeconds;
        }

        if (bRasterTruncated)
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.bTruncated = true;
            OutOutput.RefusalReason = TEXT("The wall-clock budget stopped triangle rasterisation.");
            break;
        }
    }

    OutOutput.MeshSeconds = World.ExploreMeshSeconds;
    OutOutput.RasterSeconds = FPlatformTime::Seconds() - RasterStartSeconds;
    const int32 AdditionalViewCount = FMath::Max(0, OutOutput.Frames.Num() - 1);
    OutOutput.AdditionalViewRasterSeconds = AdditionalViewCount > 0
        ? (OutOutput.RasterSeconds - OutOutput.FirstViewRasterSeconds)
            / static_cast<double>(AdditionalViewCount)
        : 0.0;
    if (!OutOutput.bTruncated)
    {
        OutOutput.Status = TEXT("ok");
    }
    return !OutOutput.bTruncated;
}

void DrawPointMarker(
    TArray<FColor>& Pixels,
    int32 Width,
    int32 Height,
    const FVector& Point,
    const FVector& CameraPosition,
    const FExploreCameraBasis& Basis,
    const FColor& Color,
    bool& bOutProjected)
{
    FIntPoint Pixel = FIntPoint::ZeroValue;
    bOutProjected = ProjectPoint(
        Point, CameraPosition, Basis, Width, Height, Pixel);
    if (!bOutProjected)
    {
        return;
    }

    constexpr int32 MarkerRadius = 7;
    DrawLine(
        Pixels, Width, Height,
        Pixel.X - MarkerRadius, Pixel.Y,
        Pixel.X + MarkerRadius, Pixel.Y,
        Color);
    DrawLine(
        Pixels, Width, Height,
        Pixel.X, Pixel.Y - MarkerRadius,
        Pixel.X, Pixel.Y + MarkerRadius,
        Color);
    DrawLine(
        Pixels, Width, Height,
        Pixel.X - 4, Pixel.Y - 4,
        Pixel.X + 4, Pixel.Y + 4,
        Color);
    DrawLine(
        Pixels, Width, Height,
        Pixel.X - 4, Pixel.Y + 4,
        Pixel.X + 4, Pixel.Y - 4,
        Color);
}

bool RunFailureBoundaryRender(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    const FExploreWalkOutput& Walk,
    FExploreRenderOutput& InOutOutput,
    FExploreBudget& Budget)
{
    const FVoxelPlayerFitWalkReport& Report = Walk.Report;
    if (!Report.bHasAgentFinalPosition || !Report.bHasTargetComponentNearestCell)
    {
        return false;
    }

    const FVector AgentFinal = Report.AgentFinalVoxels;
    const FVector TargetComponentCell = Report.TargetComponentNearestVoxels;
    const FVector LastReached = Report.LastReachedVoxels;
    const bool bHaveLastReached = Report.bHasLastReachedPosition;
    const FVector Focus = (AgentFinal + TargetComponentCell) * 0.5f;
    const FVector Segment = TargetComponentCell - AgentFinal;
    const FVector SegmentDirection = Segment.GetSafeNormal();
    if (SegmentDirection.IsNearlyZero())
    {
        return false;
    }
    FVector ViewSide = FVector::CrossProduct(SegmentDirection, FVector::UpVector).GetSafeNormal();
    if (ViewSide.IsNearlyZero())
    {
        ViewSide = FVector::CrossProduct(SegmentDirection, FVector::RightVector).GetSafeNormal();
    }
    const float SegmentLength = Segment.Size();
    const float ViewSideOffset = FMath::Min(64.0f, FMath::Max(16.0f, 0.25f * SegmentLength));
    // Failure-focus views are still required to originate from the fitted graph. The old
    // implementation nudged the camera four voxels toward/away from the boundary and could put
    // the viewpoint in the very rock that this diagnostic is meant to explain.
    const FVector CameraCandidates[] = {
        AgentFinal,
        bHaveLastReached ? LastReached : AgentFinal,
    };
    const FVector ViewTargets[] = {
        Focus + ViewSide * ViewSideOffset,
        Focus - ViewSide * ViewSideOffset,
    };

    for (int32 ViewIndex = 0; ViewIndex < UE_ARRAY_COUNT(ViewTargets); ++ViewIndex)
    {
        if (Budget.ShouldStop(TEXT("failure-focus-render")))
        {
            InOutOutput.Status = TEXT("truncated");
            InOutOutput.bTruncated = true;
            InOutOutput.RefusalReason = TEXT(
                "The wall-clock budget stopped failure-focus viewpoint generation.");
            return false;
        }

        const FVector CameraSeedPose = CameraCandidates[ViewIndex];
        const FVector CameraPosition = CameraSeedPose
            + FVector::UpVector * (FVoxelPlayerCapsuleConstants::HalfHeightVoxels - 0.5f);
        const float CameraDensity = World.Generator->GetDensityAt(
            CameraPosition.X, CameraPosition.Y, CameraPosition.Z);
        if (!FMath::IsFinite(CameraDensity) || !(CameraDensity > 0.0f))
        {
            UE_LOG(LogTemp, Warning,
                TEXT("[VoxelForgeExplore] refusing failure-focus camera %d: fitted pose is not air."),
                ViewIndex);
            return false;
        }
        const FVector Target = ViewTargets[ViewIndex];
        TArray<FColor> Pixels;
        int32 HitPixels = 0;
        bool bRasterTruncated = false;
        if (!RasterizeExploreMesh(
                Arguments,
                World,
                CameraPosition,
                Target,
                Budget,
                Pixels,
                HitPixels,
                bRasterTruncated))
        {
            InOutOutput.Status = TEXT("error");
            InOutOutput.RefusalReason = TEXT("Could not construct failure-focus mesh raster.");
            return false;
        }

        FExploreCameraBasis Basis;
        if (!BuildCameraBasis(
                CameraPosition,
                Target,
                70.0f,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                Basis))
        {
            return false;
        }

        bool bAgentProjected = false;
        bool bTargetProjected = false;
        bool bLastReachedProjected = false;
        DrawPointMarker(
            Pixels,
            Arguments.RenderWidth,
            Arguments.RenderHeight,
            AgentFinal,
            CameraPosition,
            Basis,
            FColor(242, 72, 72, 255),
            bAgentProjected);
        DrawPointMarker(
            Pixels,
            Arguments.RenderWidth,
            Arguments.RenderHeight,
            TargetComponentCell,
            CameraPosition,
            Basis,
            FColor(72, 242, 112, 255),
            bTargetProjected);
        if (bHaveLastReached)
        {
            DrawPointMarker(
                Pixels,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                LastReached,
                CameraPosition,
                Basis,
                FColor(242, 176, 56, 255),
                bLastReachedProjected);
        }

        FIntPoint AgentPixel = FIntPoint::ZeroValue;
        FIntPoint TargetPixel = FIntPoint::ZeroValue;
        if (ProjectPoint(
                AgentFinal,
                CameraPosition,
                Basis,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                AgentPixel)
            && ProjectPoint(
                TargetComponentCell,
                CameraPosition,
                Basis,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                TargetPixel))
        {
            DrawLine(
                Pixels,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                AgentPixel.X,
                AgentPixel.Y,
                TargetPixel.X,
                TargetPixel.Y,
                FColor(244, 214, 72, 255));
        }

        FExploreRenderFrame& Frame = InOutOutput.Frames.AddDefaulted_GetRef();
        Frame.FileName = FString::Printf(TEXT("failure_boundary_%02d.png"), ViewIndex);
        Frame.Purpose = TEXT("agent_final_red_target_component_nearest_green_last_reached_orange");
        Frame.CameraSeedSource = bHaveLastReached && ViewIndex == 1
            ? TEXT("last_reached_player_fit")
            : TEXT("agent_final_player_fit");
        Frame.CameraSeedPoseVoxels = CameraSeedPose;
        Frame.CameraVoxels = CameraPosition;
        Frame.TargetVoxels = Target;
        Frame.HitPixels = HitPixels;
        Frame.bFailureMarkersProjected = bAgentProjected && bTargetProjected
            && (!bHaveLastReached || bLastReachedProjected);
        Frame.bPartial = bRasterTruncated;

        bool bScaleMarkerProjected = false;
        DrawScaleMarker(
            Pixels,
            Arguments.RenderWidth,
            Arguments.RenderHeight,
            CameraPosition,
            Target,
            Basis,
            bScaleMarkerProjected);
        Frame.bScaleMarkerProjected = bScaleMarkerProjected;

        FString Error;
        if (!SavePng(
                FPaths::Combine(Arguments.OutDirectory, Frame.FileName),
                Pixels,
                Arguments.RenderWidth,
                Arguments.RenderHeight,
                Error))
        {
            InOutOutput.Status = TEXT("error");
            InOutOutput.RefusalReason = Error;
            return false;
        }

        if (bRasterTruncated)
        {
            InOutOutput.Status = TEXT("truncated");
            InOutOutput.bTruncated = true;
            InOutOutput.RefusalReason = TEXT(
                "The wall-clock budget stopped failure-focus rasterisation.");
            return false;
        }
    }

    return true;
}

bool RunWalk(
    const FExploreArguments& Arguments,
    const FExploreWorld& World,
    FExploreWalkOutput& OutOutput,
    FExploreBudget& Budget)
{
    OutOutput = FExploreWalkOutput();
    OutOutput.WindowPolicy = NeedsOriginInWindow(Arguments.Archetype)
        ? TEXT("origin-inclusive target-strate passage-envelope AABB + margin")
        : TEXT("target-strate passage-envelope AABB + margin");

    const int64 EstimatedWorkingBytes = static_cast<int64>(Arguments.MaxWalkCells)
        * EstimatedWalkBytesPerCell;
    if (EstimatedWorkingBytes > MaxWalkWorkingBytes)
    {
        OutOutput.Status = TEXT("refused");
        OutOutput.RefusalReason = FString::Printf(
            TEXT("Refused before sampling: estimated walk memory %lld bytes exceeds cap %lld bytes."),
            static_cast<long long>(EstimatedWorkingBytes),
            static_cast<long long>(MaxWalkWorkingBytes));
        return false;
    }
    if (Budget.ShouldStop(TEXT("walk")))
    {
        OutOutput.Status = TEXT("truncated");
        OutOutput.RefusalReason = TEXT("The wall-clock budget elapsed before walk sampling.");
        return false;
    }

    const FVoxelPassage* ArrivalPassage = nullptr;
    const FVoxelPassage* DeparturePassage = nullptr;
    if (!FindMouths(
            *World.Manager,
            Arguments.Slot,
            OutOutput.ArrivalVoxels,
            OutOutput.DepartureVoxels,
            OutOutput.ArrivalPassageCount,
            OutOutput.DeparturePassageCount,
            ArrivalPassage,
            DeparturePassage))
    {
        OutOutput.Status = TEXT("refused");
        OutOutput.RefusalReason = TEXT(
            "The target slot did not have both one-step chain mouths in the generated passage list.");
        return false;
    }
    OutOutput.bHasArrival = true;
    OutOutput.bHasDeparture = true;

    FVoxelStrateMeasureSettings Settings;
    Settings.SampleStep = 1;
    Settings.MaxCells = Arguments.MaxWalkCells;
    Settings.MaxRouteRetries = 16;
    Settings.CoverPointA = FVector2D(OutOutput.ArrivalVoxels.X, OutOutput.ArrivalVoxels.Y);
    Settings.CoverPointB = FVector2D(OutOutput.DepartureVoxels.X, OutOutput.DepartureVoxels.Y);
    Settings.CoverMarginVoxels = FMath::CeilToFloat(
        Settings.PlayerCapsuleRadiusVoxels) + 2.0f;

    // A mouth-AABB is not a landing window: the landing door and its local apron can legitimately
    // leave that box before the player reaches the next room. Expand the same two-point box just
    // enough to contain the selected production mouth envelope. This is still a bounded,
    // deterministic measurement window; the central inter-strate descent belongs to the adjacent
    // strata and is not folded into this intra-strate walk question.
    const float WindowMinX = FMath::Min(OutOutput.ArrivalVoxels.X, OutOutput.DepartureVoxels.X);
    const float WindowMaxX = FMath::Max(OutOutput.ArrivalVoxels.X, OutOutput.DepartureVoxels.X);
    const float WindowMinY = FMath::Min(OutOutput.ArrivalVoxels.Y, OutOutput.DepartureVoxels.Y);
    const float WindowMaxY = FMath::Max(OutOutput.ArrivalVoxels.Y, OutOutput.DepartureVoxels.Y);
    const auto IncludeTargetPassageEnvelope = [&](
        const FVoxelPassage* Passage,
        const FVoxelPassageLanding& Landing)
    {
        if (Passage == nullptr)
        {
            return;
        }

        const auto IncludeXY = [&](const FVector& Point, float Radius)
        {
            if (!FMath::IsFinite(Point.X) || !FMath::IsFinite(Point.Y)
                || !FMath::IsFinite(Point.Z) || !FMath::IsFinite(Radius))
            {
                return;
            }
            const float AbsRadius = FMath::Abs(Radius);
            // Include control points whose centreline belongs to the measured strate. A control
            // point just outside the boundary belongs to the adjacent strate's descent; pulling
            // that whole switchback into this bounded walk box can multiply the sampled volume
            // without improving the intra-strate mouth-to-mouth question.
            if (Point.Z < static_cast<float>(World.TargetBottomWorldZ)
                || Point.Z > static_cast<float>(World.TargetTopWorldZ))
            {
                return;
            }
            const float ExcessX = FMath::Max(
                0.0f,
                FMath::Max(
                    WindowMinX - (Point.X + AbsRadius),
                    (Point.X - AbsRadius) - WindowMaxX));
            const float ExcessY = FMath::Max(
                0.0f,
                FMath::Max(
                    WindowMinY - (Point.Y + AbsRadius),
                    (Point.Y - AbsRadius) - WindowMaxY));
            Settings.CoverMarginVoxels = FMath::Max(
                Settings.CoverMarginVoxels,
                FMath::Max(ExcessX, ExcessY));
        };

        IncludeXY(
            Landing.StandingPoint,
            Landing.HalfWidth + VoxelPassageGeometry::LandingCarveBlendVoxels);
        // The first/last three points are the production mouth, apron, and first slope section.
        // Do not pull the whole inter-strate switchback into the bounded target-strate test.
        const int32 NumLocalPoints = FMath::Min(3, Passage->ControlPoints.Num());
        const bool bUseUpperEnd = &Landing == &Passage->UpperLanding;
        const int32 FirstPoint = bUseUpperEnd
            ? 0 : FMath::Max(0, Passage->ControlPoints.Num() - NumLocalPoints);
        const int32 LastPoint = bUseUpperEnd
            ? NumLocalPoints : Passage->ControlPoints.Num();
        for (int32 PointIndex = FirstPoint; PointIndex < LastPoint; ++PointIndex)
        {
            const float Radius = Passage->ControlRadii.IsValidIndex(PointIndex)
                ? Passage->ControlRadii[PointIndex] : Passage->Radius;
            IncludeXY(Passage->ControlPoints[PointIndex], Radius
                + VoxelPassageGeometry::LandingCarveBlendVoxels);
        }
    };
    IncludeTargetPassageEnvelope(
        ArrivalPassage,
        ArrivalPassage != nullptr ? ArrivalPassage->LowerLanding : FVoxelPassageLanding());
    IncludeTargetPassageEnvelope(
        DeparturePassage,
        DeparturePassage != nullptr ? DeparturePassage->UpperLanding : FVoxelPassageLanding());
    Settings.bIncludeOriginInCoverWindow = NeedsOriginInWindow(Arguments.Archetype);

    TArray<FVector> LandingRoomProbePoints;

    auto AppendLandingRoomProbes = [&LandingRoomProbePoints](
        const FVoxelPassageLanding& Landing)
    {
        const float ProbeOffset = FMath::Min(
            2.0f,
            FMath::Max(0.0f, Landing.HalfWidth - 2.0f));
        LandingRoomProbePoints.Add(Landing.StandingPoint);
        LandingRoomProbePoints.Add(
            Landing.StandingPoint + FVector(ProbeOffset, 0.0f, 0.0f));
        LandingRoomProbePoints.Add(
            Landing.StandingPoint + FVector(-ProbeOffset, 0.0f, 0.0f));
        LandingRoomProbePoints.Add(
            Landing.StandingPoint + FVector(0.0f, ProbeOffset, 0.0f));
        LandingRoomProbePoints.Add(
            Landing.StandingPoint + FVector(0.0f, -ProbeOffset, 0.0f));
    };
    if (ArrivalPassage != nullptr)
    {
        AppendLandingRoomProbes(ArrivalPassage->LowerLanding);
    }
    if (DeparturePassage != nullptr)
    {
        AppendLandingRoomProbes(DeparturePassage->UpperLanding);
    }

    const FGeneratorDensitySampler Sampler(*World.Generator);
    if (!VF_MeasurePlayerFitWalkWithSampler(
            Sampler,
            World.TargetBottomWorldZ,
            World.TargetTopWorldZ,
            World.TargetBoundarySealThickness,
            OutOutput.ArrivalVoxels,
            OutOutput.DepartureVoxels,
            Settings,
            OutOutput.Report,
            &LandingRoomProbePoints,
            &OutOutput.SharedSampleGrid))
    {
        OutOutput.Status = TEXT("refused");
        OutOutput.RefusalReason = OutOutput.Report.RefusalReason;
        return false;
    }

    // Camera seeds are selected from this exact captured mask. The first valid fit cell anchors
    // the bounded render mesh; subsequent cells are kept local to that anchor so the mesh region
    // contains every requested viewpoint rather than silently rendering a distant empty box.
    OutOutput.CameraSeedPoses.Reset();
    OutOutput.CameraSeedSources.Reset();
    FVector CameraAnchor = FVector::ZeroVector;
    bool bHaveCameraAnchor = false;
    const auto AddCameraSeed = [&](const FVector& Position, const TCHAR* Source)
    {
        if (!FMath::IsFinite(Position.X) || !FMath::IsFinite(Position.Y)
            || !FMath::IsFinite(Position.Z)
            || !OutOutput.SharedSampleGrid.ContainsPoint(Position))
        {
            return;
        }
        const float Step = static_cast<float>(OutOutput.SharedSampleGrid.SampleStep);
        const int32 X = FMath::Clamp(
            FMath::FloorToInt((Position.X - OutOutput.SharedSampleGrid.MinX) / Step),
            0,
            OutOutput.SharedSampleGrid.NumX - 1);
        const int32 Y = FMath::Clamp(
            FMath::FloorToInt((Position.Y - OutOutput.SharedSampleGrid.MinY) / Step),
            0,
            OutOutput.SharedSampleGrid.NumY - 1);
        const int32 Z = FMath::Clamp(
            FMath::FloorToInt((Position.Z - OutOutput.SharedSampleGrid.MinZ) / Step),
            0,
            OutOutput.SharedSampleGrid.NumZ - 1);
        const int32 Cell = OutOutput.SharedSampleGrid.Index(X, Y, Z);
        if (!OutOutput.SharedSampleGrid.PlayerFitMask.IsValidIndex(Cell)
            || OutOutput.SharedSampleGrid.PlayerFitMask[Cell] == 0u)
        {
            return;
        }
        if (!bHaveCameraAnchor)
        {
            CameraAnchor = Position;
            bHaveCameraAnchor = true;
        }
        if (FVector::DistSquared(Position, CameraAnchor) > FMath::Square(40.0f))
        {
            return;
        }
        for (const FVector& Existing : OutOutput.CameraSeedPoses)
        {
            if (Existing.Equals(Position, 0.001f))
            {
                return;
            }
        }
        OutOutput.CameraSeedPoses.Add(Position);
        OutOutput.CameraSeedSources.Add(
            Source != nullptr ? FString(Source)
                              : FString::Printf(TEXT("player_fit_%02d"),
                                  OutOutput.CameraSeedPoses.Num() - 1));
    };
    AddCameraSeed(OutOutput.ArrivalVoxels, TEXT("arrival_player_fit"));
    AddCameraSeed(OutOutput.DepartureVoxels, TEXT("departure_player_fit"));
    if (OutOutput.Report.bHasLastReachedPosition)
    {
        AddCameraSeed(
            OutOutput.Report.LastReachedVoxels,
            TEXT("last_reached_player_fit"));
    }
    if (OutOutput.Report.bHasAgentFinalPosition)
    {
        AddCameraSeed(
            OutOutput.Report.AgentFinalVoxels,
            TEXT("agent_final_player_fit"));
    }
    if (!bHaveCameraAnchor)
    {
        for (int32 Cell = 0;
             Cell < OutOutput.SharedSampleGrid.PlayerFitMask.Num();
             ++Cell)
        {
            if (OutOutput.SharedSampleGrid.PlayerFitMask[Cell] == 0u)
            {
                continue;
            }
            const int32 Plane = OutOutput.SharedSampleGrid.NumX
                * OutOutput.SharedSampleGrid.NumY;
            const int32 Z = Cell / Plane;
            const int32 InPlane = Cell - Z * Plane;
            const int32 Y = InPlane / OutOutput.SharedSampleGrid.NumX;
            const int32 X = InPlane - Y * OutOutput.SharedSampleGrid.NumX;
            AddCameraSeed(
                FVector(
                    OutOutput.SharedSampleGrid.MinX
                        + (static_cast<float>(X) + 0.5f)
                            * OutOutput.SharedSampleGrid.SampleStep,
                    OutOutput.SharedSampleGrid.MinY
                        + (static_cast<float>(Y) + 0.5f)
                            * OutOutput.SharedSampleGrid.SampleStep,
                    OutOutput.SharedSampleGrid.MinZ
                        + (static_cast<float>(Z) + 0.5f)
                            * OutOutput.SharedSampleGrid.SampleStep),
                TEXT("player_fit_grid"));
            if (bHaveCameraAnchor)
            {
                break;
            }
        }
    }
    if (bHaveCameraAnchor)
    {
        const int32 NumCandidates = OutOutput.SharedSampleGrid.PlayerFitMask.Num();
        for (int32 Cell = 0; Cell < NumCandidates && OutOutput.CameraSeedPoses.Num() < 8; ++Cell)
        {
            if (OutOutput.SharedSampleGrid.PlayerFitMask[Cell] == 0u)
            {
                continue;
            }
            const int32 Plane = OutOutput.SharedSampleGrid.NumX
                * OutOutput.SharedSampleGrid.NumY;
            const int32 Z = Cell / Plane;
            const int32 InPlane = Cell - Z * Plane;
            const int32 Y = InPlane / OutOutput.SharedSampleGrid.NumX;
            const int32 X = InPlane - Y * OutOutput.SharedSampleGrid.NumX;
            AddCameraSeed(
                FVector(
                    OutOutput.SharedSampleGrid.MinX
                        + (static_cast<float>(X) + 0.5f)
                            * OutOutput.SharedSampleGrid.SampleStep,
                    OutOutput.SharedSampleGrid.MinY
                        + (static_cast<float>(Y) + 0.5f)
                            * OutOutput.SharedSampleGrid.SampleStep,
                    OutOutput.SharedSampleGrid.MinZ
                        + (static_cast<float>(Z) + 0.5f)
                            * OutOutput.SharedSampleGrid.SampleStep),
                TEXT("player_fit_grid"));
        }
    }

    // The origin observation is now a view over the shared primary grid. A second, expanded
    // walk would defeat the one-grid contract; callers that need origin coverage must request an
    // origin-inclusive archetype window, which is already selected before the single sample pass.
    OutOutput.bOriginCheckAttempted = true;
    if (OutOutput.Report.bOriginColumnInSampledWindow)
    {
        OutOutput.OriginCheckReport = OutOutput.Report;
        OutOutput.bOriginCheckAvailable = true;
    }
    else
    {
        OutOutput.OriginCheckRefusalReason = TEXT(
            "Origin is outside the shared primary sample window; no second grid was sampled.");
    }
    const int32 ArrivalProbeCount = ArrivalPassage != nullptr ? 5 : 0;
    const int32 DepartureProbeCount = DeparturePassage != nullptr ? 5 : 0;
    const int32 LandingProbeCount = ArrivalProbeCount + DepartureProbeCount;
    OutOutput.ArrivalLandingRoomProbeCount = ArrivalProbeCount;
    OutOutput.DepartureLandingRoomProbeCount = DepartureProbeCount;
    for (int32 ProbeIndex = 0;
         ProbeIndex < FMath::Min(LandingProbeCount,
             OutOutput.Report.ComponentProbePlayerFit.Num());
         ++ProbeIndex)
    {
        const bool bPlayerFit = OutOutput.Report.ComponentProbePlayerFit[ProbeIndex] != 0u;
        const bool bInArrivalComponent =
            OutOutput.Report.ComponentProbeInStartComponent.IsValidIndex(ProbeIndex)
            && OutOutput.Report.ComponentProbeInStartComponent[ProbeIndex] != 0u;
        if (ProbeIndex < ArrivalProbeCount)
        {
            OutOutput.ArrivalLandingRoomPlayerFitProbeCount += bPlayerFit ? 1 : 0;
            OutOutput.ArrivalLandingRoomArrivalComponentProbeCount +=
                bInArrivalComponent ? 1 : 0;
        }
        else
        {
            OutOutput.DepartureLandingRoomPlayerFitProbeCount += bPlayerFit ? 1 : 0;
            OutOutput.DepartureLandingRoomArrivalComponentProbeCount +=
                bInArrivalComponent ? 1 : 0;
        }
    }
    if (Budget.ShouldStop(TEXT("walk")))
    {
        OutOutput.Status = TEXT("truncated");
        OutOutput.RefusalReason = TEXT("The wall-clock budget elapsed after walk sampling.");
        return false;
    }
    OutOutput.Status = TEXT("ok");
    return true;
}

int64 EstimateExportWorkingBytes(int32 RegionSize)
{
    const int64 TileCells = static_cast<int64>(CHUNK_SIZE)
        * static_cast<int64>(CHUNK_SIZE)
        * static_cast<int64>(CHUNK_SIZE);
    const int64 TileGridSamples = static_cast<int64>(CHUNK_SIZE + 3)
        * static_cast<int64>(CHUNK_SIZE + 3)
        * static_cast<int64>(CHUNK_SIZE + 3);
    // This preflight covers one canonical tile's scalar grid, edge map, mesh arrays, and temporary
    // triangle lists. The run-level canonical aggregate is retained separately so render and
    // export consume the same mesh. RegionSize is still accepted here to keep the call site's
    // contract explicit.
    (void)RegionSize;
    return TileGridSamples * static_cast<int64>(sizeof(float)) + TileCells * 448ll;
}

bool WriteUtf8(FArchive& Archive, const FString& Text)
{
    FTCHARToUTF8 Converted(*Text);
    if (Converted.Length() > 0)
    {
        Archive.Serialize(const_cast<ANSICHAR*>(Converted.Get()), Converted.Length());
    }
    return !Archive.IsError();
}

bool ValidateCanonicalTile(const FVoxelMeshData& MeshData, FString& OutError)
{
    if (MeshData.Vertices.Num() != MeshData.Normals.Num()
        || MeshData.Vertices.Num() != MeshData.UVs.Num()
        || MeshData.Vertices.Num() != MeshData.Colors.Num()
        || MeshData.Triangles.Num() % 3 != 0)
    {
        OutError = TEXT("Canonical mesher returned non-parallel mesh arrays.");
        return false;
    }
    return true;
}

bool ExploreMetricVectorIsFinite(const FVector& Value)
{
    return FMath::IsFinite(Value.X) && FMath::IsFinite(Value.Y) && FMath::IsFinite(Value.Z);
}

FIntVector ExploreMetricWeldPosition(const FVector& PositionCm)
{
    // Mesh positions are Unreal centimetres. 0.01 cm is deliberately much smaller than a
    // marching-cubes cell and only absorbs independent-tile floating-point round-off.
    constexpr float WeldQuantumCm = 0.01f;
    return FIntVector(
        FMath::RoundToInt(PositionCm.X / WeldQuantumCm),
        FMath::RoundToInt(PositionCm.Y / WeldQuantumCm),
        FMath::RoundToInt(PositionCm.Z / WeldQuantumCm));
}

FExploreMeshEdgeKey ExploreMetricMakeEdgeKey(
    const FVector& PositionA,
    const FVector& PositionB)
{
    const FIntVector A = ExploreMetricWeldPosition(PositionA);
    const FIntVector B = ExploreMetricWeldPosition(PositionB);
    const bool bAFirst = A.X < B.X
        || (A.X == B.X && (A.Y < B.Y || (A.Y == B.Y && A.Z <= B.Z)));
    return bAFirst
        ? FExploreMeshEdgeKey{A, B}
        : FExploreMeshEdgeKey{B, A};
}

float ExploreMetricPercentile(const TArray<float>& SortedValues, float Quantile)
{
    if (SortedValues.Num() == 0)
    {
        return 0.0f;
    }
    const float Position = FMath::Clamp(Quantile, 0.0f, 1.0f)
        * static_cast<float>(SortedValues.Num() - 1);
    const int32 Lower = FMath::FloorToInt(Position);
    const int32 Upper = FMath::Min(Lower + 1, SortedValues.Num() - 1);
    return FMath::Lerp(SortedValues[Lower], SortedValues[Upper], Position - static_cast<float>(Lower));
}

bool MeasureExploreMesh(
    const FVoxelMeshData& MeshData,
    FExploreMeshMetrics& OutMetrics,
    FString& OutError)
{
    OutMetrics = FExploreMeshMetrics();
    if (!ValidateCanonicalTile(MeshData, OutError))
    {
        return false;
    }

    const int32 NumTriangles = MeshData.Triangles.Num() / 3;
    OutMetrics.VertexCount = MeshData.Vertices.Num();
    OutMetrics.TriangleCount = NumTriangles;

    TArray<float> EdgeLengthsMeters;
    TArray<float> DihedralAnglesDegrees;
    TArray<float> FaceNormalDivergencesDegrees;
    EdgeLengthsMeters.Reserve(NumTriangles * 3);
    DihedralAnglesDegrees.Reserve(NumTriangles * 2);
    FaceNormalDivergencesDegrees.Reserve(NumTriangles);

    TArray<FVector> FaceNormals;
    FaceNormals.Init(FVector::ZeroVector, NumTriangles);
    TArray<uint8> ValidFaceNormals;
    ValidFaceNormals.Init(0, NumTriangles);
    TMap<FExploreMeshEdgeKey, FExploreMeshEdgeIncident> EdgeIncidents;
    EdgeIncidents.Reserve(FMath::Max(1, NumTriangles * 2));

    const auto AddEdgeIncident = [&EdgeIncidents](
        const FVector& PositionA, const FVector& PositionB, int32 TriangleIndex)
    {
        const FExploreMeshEdgeKey Key = ExploreMetricMakeEdgeKey(PositionA, PositionB);
        if (Key.First == Key.Second)
        {
            return;
        }
        FExploreMeshEdgeIncident& Incident = EdgeIncidents.FindOrAdd(Key);
        if (Incident.IncidentCount == 0)
        {
            Incident.FirstTriangle = TriangleIndex;
        }
        else if (Incident.IncidentCount == 1)
        {
            Incident.SecondTriangle = TriangleIndex;
        }
        Incident.IncidentCount = FMath::Min(Incident.IncidentCount + 1, 3);
    };

    for (int32 TriangleIndex = 0; TriangleIndex < NumTriangles; ++TriangleIndex)
    {
        const int32 Base = TriangleIndex * 3;
        const int32 IndexA = MeshData.Triangles[Base];
        const int32 IndexB = MeshData.Triangles[Base + 1];
        const int32 IndexC = MeshData.Triangles[Base + 2];
        if (!MeshData.Vertices.IsValidIndex(IndexA)
            || !MeshData.Vertices.IsValidIndex(IndexB)
            || !MeshData.Vertices.IsValidIndex(IndexC)
            || !MeshData.Normals.IsValidIndex(IndexA)
            || !MeshData.Normals.IsValidIndex(IndexB)
            || !MeshData.Normals.IsValidIndex(IndexC))
        {
            OutError = TEXT("Surface metric measurement saw an out-of-range mesh index.");
            return false;
        }

        const FVector& A = MeshData.Vertices[IndexA];
        const FVector& B = MeshData.Vertices[IndexB];
        const FVector& C = MeshData.Vertices[IndexC];
        if (!ExploreMetricVectorIsFinite(A)
            || !ExploreMetricVectorIsFinite(B)
            || !ExploreMetricVectorIsFinite(C))
        {
            OutError = TEXT("Surface metric measurement saw a non-finite vertex.");
            return false;
        }

        EdgeLengthsMeters.Add(FVector::Dist(A, B) * 0.01f);
        EdgeLengthsMeters.Add(FVector::Dist(B, C) * 0.01f);
        EdgeLengthsMeters.Add(FVector::Dist(C, A) * 0.01f);

        const FVector Cross = FVector::CrossProduct(B - A, C - A);
        if (Cross.SizeSquared() > SMALL_NUMBER)
        {
            const FVector MeanVertexNormal = (
                MeshData.Normals[IndexA]
                + MeshData.Normals[IndexB]
                + MeshData.Normals[IndexC]).GetSafeNormal();
            if (ExploreMetricVectorIsFinite(MeanVertexNormal)
                && !MeanVertexNormal.IsNearlyZero())
            {
                // The canonical marching-cubes table is emitted with the winding required by
                // the runtime mesh path, while the density-gradient normals point solid-to-air.
                // Orient the geometric face normal to that same outward convention before
                // measuring the relief divergence; otherwise a winding convention change would
                // report ~180 degrees for an otherwise smooth surface.
                FVector FaceNormal = Cross.GetSafeNormal();
                if (FVector::DotProduct(FaceNormal, MeanVertexNormal) < 0.0f)
                {
                    FaceNormal *= -1.0f;
                }
                FaceNormals[TriangleIndex] = FaceNormal;
                ValidFaceNormals[TriangleIndex] = 1;
                const float Dot = FMath::Clamp(
                    FVector::DotProduct(FaceNormal, MeanVertexNormal), -1.0f, 1.0f);
                FaceNormalDivergencesDegrees.Add(
                    FMath::RadiansToDegrees(FMath::Acos(Dot)));
                ++OutMetrics.NormalComparisonTriangleCount;
            }
        }

        AddEdgeIncident(A, B, TriangleIndex);
        AddEdgeIncident(B, C, TriangleIndex);
        AddEdgeIncident(C, A, TriangleIndex);
    }

    for (const TPair<FExploreMeshEdgeKey, FExploreMeshEdgeIncident>& Pair : EdgeIncidents)
    {
        const FExploreMeshEdgeIncident& Incident = Pair.Value;
        if (Incident.IncidentCount != 2)
        {
            continue;
        }
        ++OutMetrics.SharedEdgeCount;
        if (!ValidFaceNormals.IsValidIndex(Incident.FirstTriangle)
            || !ValidFaceNormals.IsValidIndex(Incident.SecondTriangle)
            || !ValidFaceNormals[Incident.FirstTriangle]
            || !ValidFaceNormals[Incident.SecondTriangle])
        {
            continue;
        }
        const float Dot = FMath::Clamp(
            FVector::DotProduct(
                FaceNormals[Incident.FirstTriangle],
                FaceNormals[Incident.SecondTriangle]),
            -1.0f,
            1.0f);
        DihedralAnglesDegrees.Add(FMath::RadiansToDegrees(FMath::Acos(Dot)));
    }

    EdgeLengthsMeters.Sort();
    DihedralAnglesDegrees.Sort();
    FaceNormalDivergencesDegrees.Sort();

    OutMetrics.DihedralSampleCount = DihedralAnglesDegrees.Num();
    OutMetrics.EdgeLengthP50Meters = ExploreMetricPercentile(EdgeLengthsMeters, 0.50f);
    OutMetrics.EdgeLengthP99Meters = ExploreMetricPercentile(EdgeLengthsMeters, 0.99f);
    OutMetrics.EdgeLengthMaxMeters = EdgeLengthsMeters.Num() > 0
        ? EdgeLengthsMeters.Last() : 0.0f;
    OutMetrics.DihedralP50Degrees = ExploreMetricPercentile(DihedralAnglesDegrees, 0.50f);
    OutMetrics.DihedralP75Degrees = ExploreMetricPercentile(DihedralAnglesDegrees, 0.75f);
    OutMetrics.DihedralP90Degrees = ExploreMetricPercentile(DihedralAnglesDegrees, 0.90f);
    OutMetrics.DihedralP95Degrees = ExploreMetricPercentile(DihedralAnglesDegrees, 0.95f);
    OutMetrics.DihedralP99Degrees = ExploreMetricPercentile(DihedralAnglesDegrees, 0.99f);
    if (DihedralAnglesDegrees.Num() > 0)
    {
        int32 Over20 = 0;
        int32 Over40 = 0;
        for (const float Angle : DihedralAnglesDegrees)
        {
            Over20 += Angle > 20.0f ? 1 : 0;
            Over40 += Angle > 40.0f ? 1 : 0;
        }
        OutMetrics.DihedralFractionOver20Degrees = static_cast<float>(Over20)
            / static_cast<float>(DihedralAnglesDegrees.Num());
        OutMetrics.DihedralFractionOver40Degrees = static_cast<float>(Over40)
            / static_cast<float>(DihedralAnglesDegrees.Num());
    }
    OutMetrics.FaceNormalVsMeanVertexNormalP50Degrees =
        ExploreMetricPercentile(FaceNormalDivergencesDegrees, 0.50f);
    OutMetrics.FaceNormalVsMeanVertexNormalP90Degrees =
        ExploreMetricPercentile(FaceNormalDivergencesDegrees, 0.90f);
    OutError.Reset();
    return true;
}

bool WriteObjHeader(FArchive& Archive)
{
    bool bOk = WriteUtf8(Archive, TEXT("# VoxelForge authoritative marching-cubes mesh\n"));
    bOk = bOk && WriteUtf8(Archive,
        TEXT("# Positions are metres; UVs retain canonical voxel-space values; source winding is preserved.\n"));
    bOk = bOk && WriteUtf8(Archive, TEXT("o VoxelForgeExplore\n"));
    return bOk && !Archive.IsError();
}

bool WriteObjMesh(
    FArchive& Archive,
    const FVoxelMeshData& MeshData,
    FExploreBudget& Budget,
    FString& OutError,
    bool& bOutTruncated,
    int32& OutVerticesWritten,
    int32& OutTrianglesWritten)
{
    bOutTruncated = false;
    OutVerticesWritten = 0;
    OutTrianglesWritten = 0;
    if (!ValidateCanonicalTile(MeshData, OutError))
    {
        return false;
    }

    bool bOk = true;
    for (int32 VertexIndex = 0; VertexIndex < MeshData.Vertices.Num(); ++VertexIndex)
    {
        if ((VertexIndex & 255) == 0 && Budget.ShouldStop(TEXT("export-write")))
        {
            bOutTruncated = true;
            return true;
        }
        const FVector& Vertex = MeshData.Vertices[VertexIndex];
        bOk = bOk && WriteUtf8(Archive, FString::Printf(
            TEXT("v %.9f %.9f %.9f\n"),
            Vertex.X / 100.0,
            Vertex.Y / 100.0,
            Vertex.Z / 100.0));
        ++OutVerticesWritten;
    }
    for (int32 UVIndex = 0; UVIndex < MeshData.UVs.Num(); ++UVIndex)
    {
        if ((UVIndex & 255) == 0 && Budget.ShouldStop(TEXT("export-write")))
        {
            bOutTruncated = true;
            return true;
        }
        const FVector2D& UV = MeshData.UVs[UVIndex];
        bOk = bOk && WriteUtf8(Archive, FString::Printf(
            TEXT("vt %.9f %.9f\n"), UV.X, UV.Y));
    }
    for (int32 NormalIndex = 0; NormalIndex < MeshData.Normals.Num(); ++NormalIndex)
    {
        if ((NormalIndex & 255) == 0 && Budget.ShouldStop(TEXT("export-write")))
        {
            bOutTruncated = true;
            return true;
        }
        const FVector& Normal = MeshData.Normals[NormalIndex];
        bOk = bOk && WriteUtf8(Archive, FString::Printf(
            TEXT("vn %.9f %.9f %.9f\n"), Normal.X, Normal.Y, Normal.Z));
    }

    const int32 NumTriangles = MeshData.Triangles.Num() / 3;
    if (NumTriangles > 0)
    {
        bOk = bOk && WriteUtf8(Archive, TEXT("usemtl VoxelGround\n"));
    }
    for (int32 Triangle = 0; Triangle < NumTriangles; ++Triangle)
    {
        if ((Triangle & 255) == 0 && Budget.ShouldStop(TEXT("export-write")))
        {
            bOutTruncated = true;
            return true;
        }
        const int32 Base = Triangle * 3;
        const int32 A = MeshData.Triangles[Base];
        const int32 B = MeshData.Triangles[Base + 1];
        const int32 C = MeshData.Triangles[Base + 2];
        if (A < 0 || B < 0 || C < 0
            || A >= MeshData.Vertices.Num()
            || B >= MeshData.Vertices.Num()
            || C >= MeshData.Vertices.Num())
        {
            OutError = TEXT("Canonical aggregate mesh returned an out-of-range triangle index.");
            return false;
        }
        bOk = bOk && WriteUtf8(Archive, FString::Printf(
            TEXT("f %d/%d/%d %d/%d/%d %d/%d/%d\n"),
            A + 1, A + 1, A + 1,
            B + 1, B + 1, B + 1,
            C + 1, C + 1, C + 1));
        ++OutTrianglesWritten;
    }
    if (!bOk || Archive.IsError())
    {
        OutError = TEXT("Could not write the canonical aggregate OBJ.");
        return false;
    }
    return true;
}

void WriteJsonVector(FExploreJsonWriter& Writer, const TCHAR* Key, const FVector& Value, float Scale)
{
    Writer.WriteObjectStart(Key);
    Writer.WriteValue(TEXT("x"), static_cast<double>(Value.X) * Scale);
    Writer.WriteValue(TEXT("y"), static_cast<double>(Value.Y) * Scale);
    Writer.WriteValue(TEXT("z"), static_cast<double>(Value.Z) * Scale);
    Writer.WriteObjectEnd();
}

void WriteJsonIntVector(FExploreJsonWriter& Writer, const TCHAR* Key, const FIntVector& Value)
{
    Writer.WriteObjectStart(Key);
    Writer.WriteValue(TEXT("x"), Value.X);
    Writer.WriteValue(TEXT("y"), Value.Y);
    Writer.WriteValue(TEXT("z"), Value.Z);
    Writer.WriteObjectEnd();
}

void WriteJsonBounds(
    FExploreJsonWriter& Writer,
    const TCHAR* Key,
    const FIntVector& Origin,
    int32 Size,
    float VoxelToMeters)
{
    Writer.WriteObjectStart(Key);
    Writer.WriteObjectStart(TEXT("min"));
    Writer.WriteValue(TEXT("x"), Origin.X);
    Writer.WriteValue(TEXT("y"), Origin.Y);
    Writer.WriteValue(TEXT("z"), Origin.Z);
    Writer.WriteObjectEnd();
    Writer.WriteObjectStart(TEXT("max_exclusive"));
    Writer.WriteValue(TEXT("x"), Origin.X + Size);
    Writer.WriteValue(TEXT("y"), Origin.Y + Size);
    Writer.WriteValue(TEXT("z"), Origin.Z + Size);
    Writer.WriteObjectEnd();
    Writer.WriteValue(TEXT("units"), TEXT("voxels"));
    Writer.WriteValue(TEXT("voxel_size_m"), static_cast<double>(VoxelToMeters));
    Writer.WriteObjectEnd();
}

void WriteSurfaceReliefMetrics(
    FExploreJsonWriter& Writer,
    const FExploreMeshMetrics& Metrics)
{
    Writer.WriteObjectStart(TEXT("surface_relief_metrics"));
    Writer.WriteValue(TEXT("vertex_count"), Metrics.VertexCount);
    Writer.WriteValue(TEXT("triangle_count"), Metrics.TriangleCount);
    Writer.WriteValue(TEXT("shared_edge_count"), Metrics.SharedEdgeCount);
    Writer.WriteValue(TEXT("dihedral_sample_count"), Metrics.DihedralSampleCount);
    Writer.WriteValue(TEXT("normal_comparison_triangle_count"), Metrics.NormalComparisonTriangleCount);
    Writer.WriteValue(TEXT("vertex_weld_quantum_cm"), 0.01);
    Writer.WriteObjectStart(TEXT("triangle_edge_length_m"));
    Writer.WriteValue(TEXT("p50"), static_cast<double>(Metrics.EdgeLengthP50Meters));
    Writer.WriteValue(TEXT("p99"), static_cast<double>(Metrics.EdgeLengthP99Meters));
    Writer.WriteValue(TEXT("max"), static_cast<double>(Metrics.EdgeLengthMaxMeters));
    Writer.WriteObjectEnd();
    Writer.WriteObjectStart(TEXT("dihedral_angle_degrees"));
    Writer.WriteValue(TEXT("p50"), static_cast<double>(Metrics.DihedralP50Degrees));
    Writer.WriteValue(TEXT("p75"), static_cast<double>(Metrics.DihedralP75Degrees));
    Writer.WriteValue(TEXT("p90"), static_cast<double>(Metrics.DihedralP90Degrees));
    Writer.WriteValue(TEXT("p95"), static_cast<double>(Metrics.DihedralP95Degrees));
    Writer.WriteValue(TEXT("p99"), static_cast<double>(Metrics.DihedralP99Degrees));
    Writer.WriteValue(TEXT("fraction_over_20_degrees"),
        static_cast<double>(Metrics.DihedralFractionOver20Degrees));
    Writer.WriteValue(TEXT("fraction_over_40_degrees"),
        static_cast<double>(Metrics.DihedralFractionOver40Degrees));
    Writer.WriteObjectEnd();
    Writer.WriteObjectStart(TEXT("face_normal_vs_mean_vertex_normal_degrees"));
    Writer.WriteValue(TEXT("p50"),
        static_cast<double>(Metrics.FaceNormalVsMeanVertexNormalP50Degrees));
    Writer.WriteValue(TEXT("p90"),
        static_cast<double>(Metrics.FaceNormalVsMeanVertexNormalP90Degrees));
    Writer.WriteObjectEnd();
    Writer.WriteObjectEnd();
}

void WriteTunnelFloorOverrides(
    FExploreJsonWriter& Writer,
    const FExploreArguments& Arguments)
{
    Writer.WriteObjectStart(TEXT("tunnel_floor_overrides"));
    Writer.WriteValue(TEXT("legacy_enabled_override"), Arguments.bTunnelFloorEnabledOverride);
    if (Arguments.bTunnelFloorEnabledOverride)
    {
        Writer.WriteValue(TEXT("legacy_enabled_value"), Arguments.TunnelFloorEnabled != 0);
    }
    Writer.WriteValue(TEXT("enabled_ignored"), true);
    Writer.WriteValue(TEXT("terracing_override"), Arguments.bTunnelFloorTerracingOverride);
    if (Arguments.bTunnelFloorTerracingOverride)
    {
        Writer.WriteValue(TEXT("terracing"), Arguments.TunnelFloorTerracing != 0);
    }
    Writer.WriteValue(TEXT("step_height_override"), Arguments.bTunnelFloorStepOverride);
    if (Arguments.bTunnelFloorStepOverride)
    {
        Writer.WriteValue(TEXT("step_height_voxels"),
            static_cast<double>(Arguments.TunnelFloorStep));
    }
    Writer.WriteValue(TEXT("max_ledge_height_override"), Arguments.bTunnelFloorMaxLedgeOverride);
    if (Arguments.bTunnelFloorMaxLedgeOverride)
    {
        Writer.WriteValue(TEXT("max_ledge_height_voxels"),
            static_cast<double>(Arguments.TunnelFloorMaxLedge));
    }
    Writer.WriteValue(TEXT("gentle_slope_override"), Arguments.bTunnelFloorGentleOverride);
    if (Arguments.bTunnelFloorGentleOverride)
    {
        Writer.WriteValue(TEXT("gentle_slope"),
            static_cast<double>(Arguments.TunnelFloorGentle));
        Writer.WriteValue(TEXT("gentle_slope_units"), TEXT("degrees"));
    }
    Writer.WriteValue(TEXT("ledge_count_override"), Arguments.bTunnelFloorLedgesOverride);
    if (Arguments.bTunnelFloorLedgesOverride)
    {
        Writer.WriteValue(TEXT("ledge_count"), Arguments.TunnelFloorLedges);
    }
    Writer.WriteValue(TEXT("max_ledges_override"), Arguments.bTunnelFloorMaxLedgesOverride);
    if (Arguments.bTunnelFloorMaxLedgesOverride)
    {
        Writer.WriteValue(TEXT("max_ledges"), Arguments.TunnelFloorMaxLedges);
    }
    Writer.WriteValue(TEXT("passage_support_floor_writes_override"),
        Arguments.bPassageFloorWritesOverride);
    if (Arguments.bPassageFloorWritesOverride)
    {
        Writer.WriteValue(TEXT("passage_support_floor_writes"),
            Arguments.PassageFloorWrites != 0);
    }
    Writer.WriteObjectEnd();
}

FString BuildManifestJson(
    const FExploreArguments& Arguments,
    const FExploreExportOutput& Export)
{
    FString Json;
    TSharedRef<FExploreJsonWriter> Writer =
        TJsonWriterFactory<TCHAR, TCondensedJsonPrintPolicy<TCHAR>>::Create(&Json);
    Writer->WriteObjectStart();
    Writer->WriteValue(TEXT("schema_version"), 7);
    Writer->WriteValue(TEXT("format"), TEXT("OBJ"));
    Writer->WriteValue(TEXT("mesh_file"), Export.MeshFileName);
    Writer->WriteValue(TEXT("mesh_positions_units"), TEXT("metres"));
    Writer->WriteValue(TEXT("mesh_uv_units"), TEXT("voxels"));
    Writer->WriteValue(TEXT("load_notes"), TEXT(
        "Load geometry.obj directly in a browser OBJ loader; do not regenerate density. "
        "The manifest bounds are max-exclusive voxel bounds, OBJ positions are metres, and OBJ UVs "
        "are the canonical voxel-space UVs."));
    Writer->WriteValue(TEXT("skirts"), false);
    Writer->WriteValue(TEXT("vertex_count"), Export.VertexCount);
    Writer->WriteValue(TEXT("triangle_count"), Export.TriangleCount);
    Writer->WriteValue(TEXT("geometry_hash"), Export.GeometryHash);
    WriteSurfaceReliefMetrics(*Writer, Export.SurfaceMetrics);
    Writer->WriteValue(TEXT("mesh_file_size_bytes"), Export.MeshFileSizeBytes);
    Writer->WriteValue(TEXT("mesh_array_bytes_sum_over_tiles"), Export.MeshArrayBytes);
    Writer->WriteValue(TEXT("canonical_mesher_tile_cells"), CHUNK_SIZE);
    Writer->WriteValue(TEXT("canonical_mesher_tile_count"), Export.MesherTileCount);
    Writer->WriteValue(TEXT("canonical_mesher_tiles_completed"), Export.MesherTilesCompleted);
    Writer->WriteValue(TEXT("mesh_seconds"), Export.MeshSeconds);
    Writer->WriteValue(TEXT("mesh_us_per_voxel"), Export.MeshUsPerVoxel);
    Writer->WriteValue(TEXT("export_step"), Arguments.ExportStep);
    Writer->WriteValue(TEXT("truncated"), Export.bTruncated);
    Writer->WriteValue(TEXT("seed"), Arguments.Seed);
    Writer->WriteValue(TEXT("archetype"), ArchetypeName(Arguments.Archetype));
    Writer->WriteValue(TEXT("slot"), Arguments.Slot);
    Writer->WriteValue(TEXT("worms_enabled_override"), Arguments.bWormsEnabledOverride);
    if (Arguments.bWormsEnabledOverride)
    {
        Writer->WriteValue(TEXT("worms_enabled"), Arguments.bWormsEnabled);
    }
    Writer->WriteValue(TEXT("worm_strength_override"), Arguments.bWormStrengthOverride);
    if (Arguments.bWormStrengthOverride)
    {
        Writer->WriteValue(TEXT("worm_strength"), static_cast<double>(Arguments.WormStrength));
    }
    Writer->WriteValue(TEXT("tunnel_ablation_mask"),
        static_cast<int64>(VoxelDensityAblation::GetResolvedMask()));
    WriteTunnelFloorOverrides(*Writer, Arguments);
    Writer->WriteValue(TEXT("room_mouth_rise_override"), Arguments.bRoomMouthRiseOverride);
    if (Arguments.bRoomMouthRiseOverride)
    {
        Writer->WriteValue(TEXT("room_mouth_rise_strength"),
            static_cast<double>(Arguments.RoomMouthRise));
    }
    Writer->WriteValue(TEXT("room_mouth_rise_blend_override"),
        Arguments.bRoomMouthRiseBlendOverride);
    if (Arguments.bRoomMouthRiseBlendOverride)
    {
        Writer->WriteValue(TEXT("room_mouth_rise_blend_voxels"),
            static_cast<double>(Arguments.RoomMouthRiseBlend));
    }
    Writer->WriteValue(TEXT("surface_roughness_override"), Arguments.bSurfaceRoughnessOverride);
    if (Arguments.bSurfaceRoughnessOverride)
    {
        Writer->WriteValue(TEXT("surface_roughness"),
            static_cast<double>(Arguments.SurfaceRoughness));
    }
    Writer->WriteValue(TEXT("roughness_noise_type_override"),
        Arguments.bRoughnessNoiseTypeOverride);
    if (Arguments.bRoughnessNoiseTypeOverride)
    {
        Writer->WriteValue(TEXT("roughness_noise_type"),
            NoiseTypeName(Arguments.RoughnessNoiseType));
    }
    Writer->WriteValue(TEXT("roughness_frequency_override"),
        Arguments.bRoughnessFrequencyOverride);
    if (Arguments.bRoughnessFrequencyOverride)
    {
        Writer->WriteValue(TEXT("roughness_frequency"),
            static_cast<double>(Arguments.RoughnessFrequency));
    }
    Writer->WriteValue(TEXT("render_camera_override"), Arguments.bRenderCameraOverride);
    if (Arguments.bRenderCameraOverride)
    {
        WriteJsonVector(*Writer, TEXT("render_camera_voxels"), Arguments.RenderCamera, 1.0f);
    }
    WriteJsonIntVector(*Writer, TEXT("region_origin_voxels"), Export.RegionOrigin);
    WriteJsonBounds(*Writer, TEXT("region_bounds_voxels"), Export.RegionOrigin, Export.RegionSize, 0.25f);
    Writer->WriteObjectStart(TEXT("region_bounds_metres"));
    Writer->WriteObjectStart(TEXT("min"));
    Writer->WriteValue(TEXT("x"), static_cast<double>(Export.RegionOrigin.X) * 0.25);
    Writer->WriteValue(TEXT("y"), static_cast<double>(Export.RegionOrigin.Y) * 0.25);
    Writer->WriteValue(TEXT("z"), static_cast<double>(Export.RegionOrigin.Z) * 0.25);
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("max_exclusive"));
    Writer->WriteValue(TEXT("x"), static_cast<double>(Export.RegionOrigin.X + Export.RegionSize) * 0.25);
    Writer->WriteValue(TEXT("y"), static_cast<double>(Export.RegionOrigin.Y + Export.RegionSize) * 0.25);
    Writer->WriteValue(TEXT("z"), static_cast<double>(Export.RegionOrigin.Z + Export.RegionSize) * 0.25);
    Writer->WriteObjectEnd();
    Writer->WriteValue(TEXT("units"), TEXT("metres"));
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("player_dimensions"));
    Writer->WriteValue(TEXT("capsule_radius_m"), static_cast<double>(FVoxelPlayerCapsuleConstants::RadiusCentimeters) / 100.0);
    Writer->WriteValue(TEXT("capsule_width_m"), static_cast<double>(2.0f * FVoxelPlayerCapsuleConstants::RadiusCentimeters) / 100.0);
    Writer->WriteValue(TEXT("capsule_half_height_m"), static_cast<double>(FVoxelPlayerCapsuleConstants::HalfHeightCentimeters) / 100.0);
    Writer->WriteValue(TEXT("capsule_height_m"), static_cast<double>(2.0f * FVoxelPlayerCapsuleConstants::HalfHeightCentimeters) / 100.0);
    Writer->WriteValue(TEXT("max_step_height_m"), static_cast<double>(FVoxelPlayerCapsuleConstants::MaxStepHeightMeters));
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("world_invariants"));
    Writer->WriteValue(TEXT("world_radius_voxels"), 0);
    Writer->WriteValue(TEXT("lateral_regions_enabled"), false);
    Writer->WriteValue(TEXT("diff_layer_mutated"), false);
    Writer->WriteObjectEnd();
    Writer->WriteObjectEnd();
    return Writer->Close() ? Json : FString();
}

bool RunExport(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    const FExploreWalkOutput* SharedSampling,
    FExploreExportOutput& OutOutput,
    FExploreBudget& Budget)
{
    OutOutput = FExploreExportOutput();
    const double ExportStartSeconds = FPlatformTime::Seconds();
    OutOutput.RegionSize = Arguments.ExportSize;
    OutOutput.EstimatedWorkingBytes = EstimateExportWorkingBytes(Arguments.ExportSize);
    if (OutOutput.EstimatedWorkingBytes > OutOutput.WorkingMemoryCapBytes)
    {
        OutOutput.Status = TEXT("refused");
        OutOutput.RefusalReason = FString::Printf(
            TEXT("Refused before meshing: estimated working memory %lld bytes exceeds cap %lld bytes."),
            static_cast<long long>(OutOutput.EstimatedWorkingBytes),
            static_cast<long long>(OutOutput.WorkingMemoryCapBytes));
        return false;
    }

    FString MeshError;
    const bool bMeshComplete = EnsureExploreMesh(
        Arguments, World, SharedSampling, Budget, MeshError);
    if (!bMeshComplete && !Budget.bTruncated)
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = MeshError;
        return false;
    }
    OutOutput.RegionSize = World.ExploreMeshSize;
    OutOutput.MesherTileCount = World.ExploreMeshTileCount;
    OutOutput.MesherTilesCompleted = World.ExploreMeshTilesCompleted;
    OutOutput.RegionOrigin = World.ExploreMeshOrigin;

    FString Error;
    OutOutput.MeshFileName = TEXT("geometry.obj");
    OutOutput.ManifestFileName = TEXT("manifest.json");
    const FString MeshPath = FPaths::Combine(Arguments.OutDirectory, OutOutput.MeshFileName);
    TUniquePtr<FArchive> Archive(IFileManager::Get().CreateFileWriter(*MeshPath));
    if (!Archive.IsValid())
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = FString::Printf(TEXT("Could not create OBJ '%s'."), *MeshPath);
        return false;
    }
    const double ObjWriteStartSeconds = FPlatformTime::Seconds();
    if (!WriteObjHeader(*Archive))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("Could not write the OBJ header.");
        return false;
    }

    const double MeasureStartSeconds = FPlatformTime::Seconds();
    if (!MeasureExploreMesh(World.ExploreMesh, OutOutput.SurfaceMetrics, Error))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = Error;
        return false;
    }
    OutOutput.MeasureSeconds = FPlatformTime::Seconds() - MeasureStartSeconds;
    OutOutput.MeshArrayBytes = static_cast<int64>(World.ExploreMesh.Vertices.Num()) * sizeof(FVector)
        + static_cast<int64>(World.ExploreMesh.Normals.Num()) * sizeof(FVector)
        + static_cast<int64>(World.ExploreMesh.UVs.Num()) * sizeof(FVector2D)
        + static_cast<int64>(World.ExploreMesh.Colors.Num()) * sizeof(FColor)
        + static_cast<int64>(World.ExploreMesh.Triangles.Num()) * sizeof(int32);
    OutOutput.VertexCount = World.ExploreMesh.Vertices.Num();
    OutOutput.TriangleCount = World.ExploreMesh.Triangles.Num() / 3;
    OutOutput.MeshSeconds = World.ExploreMeshSeconds;
    OutOutput.MeshUsPerVoxel = Arguments.ExportSize > 0
        ? OutOutput.MeshSeconds * 1.0e6
            / static_cast<double>(Arguments.ExportSize)
            / static_cast<double>(Arguments.ExportSize)
            / static_cast<double>(Arguments.ExportSize)
        : 0.0;
    OutOutput.GeometryHash = World.ExploreGeometryHash;
    bool bObjWriteTruncated = false;
    int32 VerticesWritten = 0;
    int32 TrianglesWritten = 0;
    if (!WriteObjMesh(
            *Archive,
            World.ExploreMesh,
            Budget,
            Error,
            bObjWriteTruncated,
            VerticesWritten,
            TrianglesWritten))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = Error;
        return false;
    }
    if (Archive->IsError())
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("Could not finish the streamed OBJ.");
        return false;
    }
    Archive.Reset();
    OutOutput.MeshFileSizeBytes = IFileManager::Get().FileSize(*MeshPath);
    if (OutOutput.MeshFileSizeBytes < 0)
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("OBJ was written but its file size could not be read.");
        return false;
    }
    OutOutput.ObjWriteSeconds = FPlatformTime::Seconds() - ObjWriteStartSeconds;

    OutOutput.bTruncated = Budget.bTruncated
        || !World.bExploreMeshComplete
        || bObjWriteTruncated;
    if (OutOutput.bTruncated)
    {
        OutOutput.VertexCount = VerticesWritten;
        OutOutput.TriangleCount = TrianglesWritten;
        OutOutput.Status = TEXT("truncated");
        OutOutput.RefusalReason = !World.bExploreMeshComplete
            ? MeshError
            : TEXT("The wall-clock budget stopped export after writing a partial mesh.");
    }

    const double ManifestStartSeconds = FPlatformTime::Seconds();
    const FString ManifestJson = BuildManifestJson(Arguments, OutOutput);
    const FString ManifestJsonRepeat = BuildManifestJson(Arguments, OutOutput);
    if (ManifestJson.IsEmpty() || ManifestJsonRepeat.IsEmpty())
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("The export manifest JSON writer failed.");
        return false;
    }
    if (ManifestJson != ManifestJsonRepeat)
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("The export manifest failed its deterministic repeat assertion.");
        return false;
    }
    if (!FFileHelper::SaveStringToFile(
            ManifestJson,
            *FPaths::Combine(Arguments.OutDirectory, OutOutput.ManifestFileName),
            FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("Could not write export manifest.json.");
        return false;
    }
    OutOutput.ManifestSeconds = FPlatformTime::Seconds() - ManifestStartSeconds;
    OutOutput.ExportWallSeconds = FPlatformTime::Seconds() - ExportStartSeconds;
    OutOutput.ExportAccountingRemainderSeconds = OutOutput.ExportWallSeconds
        - (World.ExploreMeshSeconds
            + World.ExploreMeshHashSeconds
            + OutOutput.ObjWriteSeconds
            + OutOutput.ManifestSeconds);
    if (!OutOutput.bTruncated)
    {
        OutOutput.Status = TEXT("ok");
    }
    return !OutOutput.bTruncated;
}

bool RunDensitySlice(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    FExploreDensitySliceOutput& OutOutput,
    FExploreBudget& Budget)
{
    OutOutput = FExploreDensitySliceOutput();
    OutOutput.FileName = TEXT("density_slice.csv");
    OutOutput.SampleCount = Arguments.DensitySliceSamples;
    const double StartSeconds = FPlatformTime::Seconds();
    FString Csv;
    Csv.Reserve(Arguments.DensitySliceSamples * 96);
    Csv += TEXT("index,x_voxels,y_voxels,z_voxels,density\r\n");

    float PreviousDensity = 0.0f;
    bool bHavePreviousDensity = false;
    float MinDensity = TNumericLimits<float>::Max();
    float MaxDensity = -TNumericLimits<float>::Max();
    float MaxAbsDensity = 0.0f;
    for (int32 Index = 0; Index < Arguments.DensitySliceSamples; ++Index)
    {
        if ((Index & 127) == 0 && Budget.ShouldStop(TEXT("density-slice")))
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.RefusalReason = TEXT("The wall-clock budget stopped the density slice.");
            OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
            return false;
        }

        const FVector Position = Arguments.DensitySliceOrigin
            + Arguments.DensitySliceDirection
                * (Arguments.DensitySliceStep * static_cast<float>(Index));
        const float Density = World.Generator->GetDensityAt(
            Position.X, Position.Y, Position.Z);
        Csv += FString::Printf(
            TEXT("%d,%.9g,%.9g,%.9g,%.9g\r\n"),
            Index, Position.X, Position.Y, Position.Z, Density);

        if (!FMath::IsFinite(Density))
        {
            ++OutOutput.NonFiniteSampleCount;
            bHavePreviousDensity = false;
            continue;
        }
        ++OutOutput.FiniteSampleCount;
        MinDensity = FMath::Min(MinDensity, Density);
        MaxDensity = FMath::Max(MaxDensity, Density);
        MaxAbsDensity = FMath::Max(MaxAbsDensity, FMath::Abs(Density));
        if (FMath::Abs(Density) >= 0.999f)
        {
            ++OutOutput.SaturatedSampleCount;
        }
        if (bHavePreviousDensity
            && ((PreviousDensity < 0.0f && Density > 0.0f)
                || (PreviousDensity > 0.0f && Density < 0.0f)))
        {
            ++OutOutput.ZeroCrossingCount;
        }
        PreviousDensity = Density;
        bHavePreviousDensity = true;
    }

    if (OutOutput.FiniteSampleCount > 0)
    {
        OutOutput.MinDensity = MinDensity;
        OutOutput.MaxDensity = MaxDensity;
        OutOutput.MaxAbsDensity = MaxAbsDensity;
    }
    const FString Path = FPaths::Combine(Arguments.OutDirectory, OutOutput.FileName);
    if (!FFileHelper::SaveStringToFile(
            Csv, *Path, FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("Could not write density_slice.csv.");
        OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
        return false;
    }
    OutOutput.Status = TEXT("ok");
    OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeDensitySlice] file=%s samples=%d finite=%d non_finite=%d "
             "zero_crossings=%d saturated=%d min=%.9g max=%.9g max_abs=%.9g "
             "origin=(%.3f,%.3f,%.3f) direction=(%.6f,%.6f,%.6f) step=%.6g"),
        *Path, OutOutput.SampleCount, OutOutput.FiniteSampleCount,
        OutOutput.NonFiniteSampleCount, OutOutput.ZeroCrossingCount,
        OutOutput.SaturatedSampleCount, OutOutput.MinDensity,
        OutOutput.MaxDensity, OutOutput.MaxAbsDensity,
        Arguments.DensitySliceOrigin.X, Arguments.DensitySliceOrigin.Y,
        Arguments.DensitySliceOrigin.Z, Arguments.DensitySliceDirection.X,
        Arguments.DensitySliceDirection.Y, Arguments.DensitySliceDirection.Z,
        Arguments.DensitySliceStep);
    return true;
}

void ComputeTunnelCoreProbeMetrics(
    const TArray<float>& Samples,
    float StepVoxels,
    int32& OutValidCount,
    float& OutMean,
    float& OutMin,
    float& OutMax,
    float& OutPeriodicAmplitudeVoxels,
    float& OutPeriodicPeriodVoxels,
    int32& OutPeriodicMeasuredSamples,
    float& OutPeriodicMeasuredLengthVoxels,
    bool bPolynomialTrend = false)
{
    OutValidCount = 0;
    OutMean = 0.0f;
    OutMin = 0.0f;
    OutMax = 0.0f;
    OutPeriodicAmplitudeVoxels = 0.0f;
    OutPeriodicPeriodVoxels = 0.0f;
    OutPeriodicMeasuredSamples = 0;
    OutPeriodicMeasuredLengthVoxels = 0.0f;
    if (Samples.Num() < 4 || !FMath::IsFinite(StepVoxels) || StepVoxels <= 0.0f)
    {
        return;
    }

    double Sum = 0.0;
    for (int32 Index = 0; Index < Samples.Num(); ++Index)
    {
        const float Value = Samples[Index];
        if (!FMath::IsFinite(Value))
        {
            continue;
        }
        ++OutValidCount;
        Sum += Value;
        if (OutValidCount == 1)
        {
            OutMin = Value;
            OutMax = Value;
        }
        else
        {
            OutMin = FMath::Min(OutMin, Value);
            OutMax = FMath::Max(OutMax, Value);
        }
    }
    if (OutValidCount < 4)
    {
        return;
    }

    const double Count = static_cast<double>(OutValidCount);
    OutMean = static_cast<float>(Sum / Count);

    // Find the longest contiguous surface run. A missing radial crossing is not a zero-valued
    // sample: it is a hole in the measurement and must not be bridged before the spectral pass.
    int32 BestRunStart = INDEX_NONE;
    int32 BestRunEnd = INDEX_NONE;
    int32 RunStart = INDEX_NONE;
    for (int32 Index = 0; Index <= Samples.Num(); ++Index)
    {
        const bool bFinite = Index < Samples.Num() && FMath::IsFinite(Samples[Index]);
        if (bFinite)
        {
            if (RunStart == INDEX_NONE)
            {
                RunStart = Index;
            }
            continue;
        }
        if (RunStart != INDEX_NONE
            && (BestRunStart == INDEX_NONE
                || Index - RunStart > BestRunEnd - BestRunStart + 1))
        {
            BestRunStart = RunStart;
            BestRunEnd = Index - 1;
        }
        RunStart = INDEX_NONE;
    }
    const int32 BestRunLength = BestRunStart != INDEX_NONE
        ? BestRunEnd - BestRunStart + 1
        : 0;
    // The requested acceptance window is at least 40 voxels. Keep the raw crossing statistics
    // above for shorter runs, but explicitly mark their periodic result as unmeasured.
    constexpr float RequiredLengthVoxels = 40.0f;
    const int32 RequiredSampleCount = FMath::CeilToInt(RequiredLengthVoxels / StepVoxels) + 1;
    if (BestRunLength < FMath::Max(4, RequiredSampleCount))
    {
        return;
    }

    // Remove only the slow authored floor/radius trend. A 32-voxel median window is wider than
    // the 1..16 voxel rib band, so a genuine rib train survives while a single tunnel transition
    // or route slope follows the local baseline. The mouth probe uses a degree-six fit instead: the
    // room-side +/-2R window can contain one broad floor bowl, which a local median would turn
    // into a false short-period peak when only the middle 21.5 voxels remain.
    constexpr float TrendWindowVoxels = 32.0f;
    const int32 HalfWindowSamples = FMath::Max(
        1, FMath::RoundToInt(0.5f * TrendWindowVoxels / StepVoxels));
    const int32 AnalysisStart = bPolynomialTrend
        ? BestRunStart : BestRunStart + HalfWindowSamples;
    const int32 AnalysisEnd = bPolynomialTrend
        ? BestRunEnd : BestRunEnd - HalfWindowSamples;
    const int32 AnalysisCount = AnalysisEnd - AnalysisStart + 1;
    if (AnalysisCount < 4)
    {
        return;
    }

    OutPeriodicMeasuredSamples = AnalysisCount;
    OutPeriodicMeasuredLengthVoxels = static_cast<float>(AnalysisCount - 1) * StepVoxels;

    TArray<float, TInlineAllocator<257>> Residuals;
    Residuals.SetNumZeroed(AnalysisCount);
    bool bHavePolynomialTrend = false;
    if (bPolynomialTrend)
    {
        // Fit a normalized degree-six smooth trend over the complete contiguous surface run. The
        // room-side +/-2R sample can contain a broad, asymmetric floor bowl; a cubic leaves that
        // endpoint curvature in the rib-band DFT. Degree six follows that slow authored shape but
        // cannot reproduce a repeated <=16-voxel train across the full run. Keep the legacy
        // local-median measurement separately as an audit of the conservative raw instrument.
        constexpr int32 PolynomialDegree = 6;
        double Matrix[PolynomialDegree + 1][PolynomialDegree + 1] = {};
        double RightHandSide[PolynomialDegree + 1] = {};
        const double Denominator = static_cast<double>(FMath::Max(
            BestRunLength - 1, 1));
        for (int32 Index = BestRunStart; Index <= BestRunEnd; ++Index)
        {
            const double NormalizedX = -1.0
                + 2.0 * static_cast<double>(Index - BestRunStart) / Denominator;
            double Basis[PolynomialDegree + 1];
            Basis[0] = 1.0;
            for (int32 Power = 1; Power <= PolynomialDegree; ++Power)
            {
                Basis[Power] = Basis[Power - 1] * NormalizedX;
            }
            const double Value = static_cast<double>(Samples[Index]);
            for (int32 Row = 0; Row <= PolynomialDegree; ++Row)
            {
                RightHandSide[Row] += Basis[Row] * Value;
                for (int32 Column = 0; Column <= PolynomialDegree; ++Column)
                {
                    Matrix[Row][Column] += Basis[Row] * Basis[Column];
                }
            }
        }

        double Coefficients[PolynomialDegree + 1] = {};
        bHavePolynomialTrend = true;
        for (int32 PivotIndex = 0; PivotIndex <= PolynomialDegree; ++PivotIndex)
        {
            int32 PivotRow = PivotIndex;
            for (int32 Row = PivotIndex + 1; Row <= PolynomialDegree; ++Row)
            {
                if (FMath::Abs(Matrix[Row][PivotIndex])
                    > FMath::Abs(Matrix[PivotRow][PivotIndex]))
                {
                    PivotRow = Row;
                }
            }
            if (FMath::Abs(Matrix[PivotRow][PivotIndex]) <= 1.0e-12)
            {
                bHavePolynomialTrend = false;
                break;
            }
            if (PivotRow != PivotIndex)
            {
                for (int32 Column = PivotIndex;
                     Column <= PolynomialDegree; ++Column)
                {
                    Swap(Matrix[PivotIndex][Column], Matrix[PivotRow][Column]);
                }
                Swap(RightHandSide[PivotIndex], RightHandSide[PivotRow]);
            }
            for (int32 Row = PivotIndex + 1; Row <= PolynomialDegree; ++Row)
            {
                const double Factor = Matrix[Row][PivotIndex]
                    / Matrix[PivotIndex][PivotIndex];
                for (int32 Column = PivotIndex;
                     Column <= PolynomialDegree; ++Column)
                {
                    Matrix[Row][Column] -= Factor * Matrix[PivotIndex][Column];
                }
                RightHandSide[Row] -= Factor * RightHandSide[PivotIndex];
            }
        }
        if (bHavePolynomialTrend)
        {
            for (int32 Row = PolynomialDegree; Row >= 0; --Row)
            {
                double Value = RightHandSide[Row];
                for (int32 Column = Row + 1;
                     Column <= PolynomialDegree; ++Column)
                {
                    Value -= Matrix[Row][Column] * Coefficients[Column];
                }
                Coefficients[Row] = Value / Matrix[Row][Row];
            }
            for (int32 Index = AnalysisStart; Index <= AnalysisEnd; ++Index)
            {
                const double NormalizedX = -1.0
                    + 2.0 * static_cast<double>(Index - BestRunStart) / Denominator;
                double Basis = 1.0;
                double Trend = 0.0;
                for (int32 Power = 0; Power <= PolynomialDegree; ++Power)
                {
                    Trend += Coefficients[Power] * Basis;
                    Basis *= NormalizedX;
                }
                Residuals[Index - AnalysisStart] =
                    static_cast<float>(static_cast<double>(Samples[Index]) - Trend);
            }
        }
    }

    constexpr float MaxRibPeriodVoxels = 16.0f;
    const int32 MinRibFrequency = FMath::Max(
        1, FMath::CeilToInt(StepVoxels * static_cast<float>(AnalysisCount)
            / MaxRibPeriodVoxels));
    const int32 MaxFrequency = AnalysisCount / 2;
    double BestAmplitude = 0.0;
    int32 BestFrequency = 0;
    for (int32 Frequency = MinRibFrequency; Frequency <= MaxFrequency; ++Frequency)
    {
        double Real = 0.0;
        double Imaginary = 0.0;
        for (int32 Index = AnalysisStart; Index <= AnalysisEnd; ++Index)
        {
            const int32 AnalysisIndex = Index - AnalysisStart;
            if (!bHavePolynomialTrend)
            {
                TArray<float, TInlineAllocator<129>> Window;
                const int32 WindowStart = FMath::Max(BestRunStart, Index - HalfWindowSamples);
                const int32 WindowEnd = FMath::Min(BestRunEnd, Index + HalfWindowSamples);
                Window.Reserve(WindowEnd - WindowStart + 1);
                for (int32 WindowIndex = WindowStart; WindowIndex <= WindowEnd; ++WindowIndex)
                {
                    Window.Add(Samples[WindowIndex]);
                }
                Window.Sort();
                const int32 Middle = Window.Num() / 2;
                const double Median = (Window.Num() & 1) != 0
                    ? static_cast<double>(Window[Middle])
                    : 0.5 * (static_cast<double>(Window[Middle - 1])
                        + static_cast<double>(Window[Middle]));
                Residuals[AnalysisIndex] = static_cast<float>(
                    static_cast<double>(Samples[Index]) - Median);
            }
            const double Residual = static_cast<double>(Residuals[AnalysisIndex]);
            const double Angle = 2.0 * PI * static_cast<double>(Frequency)
                * static_cast<double>(AnalysisIndex) / static_cast<double>(AnalysisCount);
            Real += Residual * FMath::Cos(static_cast<float>(Angle));
            Imaginary -= Residual * FMath::Sin(static_cast<float>(Angle));
        }
        const double Amplitude = 2.0 * FMath::Sqrt(Real * Real + Imaginary * Imaginary)
            / static_cast<double>(AnalysisCount);
        if (Amplitude > BestAmplitude)
        {
            BestAmplitude = Amplitude;
            BestFrequency = Frequency;
        }
    }
    OutPeriodicAmplitudeVoxels = static_cast<float>(BestAmplitude);
    OutPeriodicPeriodVoxels = BestFrequency > 0
        ? StepVoxels * static_cast<float>(AnalysisCount)
            / static_cast<float>(BestFrequency)
        : 0.0f;
}

void ComputeTunnelMouthProbeMetrics(
    FExploreTunnelMouthProbeAxis& Axis,
    float StepVoxels)
{
    int32 LegacyValid = 0;
    float LegacyMean = 0.0f;
    float LegacyMin = 0.0f;
    float LegacyMax = 0.0f;
    int32 LegacyMeasuredSamples = 0;
    float LegacyMeasuredLength = 0.0f;
    ComputeTunnelCoreProbeMetrics(
        Axis.CrossingsVoxels, StepVoxels,
        Axis.ValidCrossings, Axis.MeanCrossingVoxels,
        Axis.MinCrossingVoxels, Axis.MaxCrossingVoxels,
        Axis.LocalMedianPeriodicAmplitudeVoxels,
        Axis.LocalMedianPeriodicPeriodVoxels,
        LegacyMeasuredSamples, LegacyMeasuredLength);
    ComputeTunnelCoreProbeMetrics(
        Axis.CrossingsVoxels, StepVoxels,
        LegacyValid, LegacyMean, LegacyMin, LegacyMax,
        Axis.PeriodicAmplitudeVoxels, Axis.PeriodicPeriodVoxels,
        Axis.PeriodicMeasuredSamples, Axis.PeriodicMeasuredLengthVoxels,
        /*bPolynomialTrend=*/true);
}

bool RunTunnelCoreProbe(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    FExploreTunnelCoreProbeOutput& OutOutput,
    FExploreBudget& Budget)
{
    OutOutput = FExploreTunnelCoreProbeOutput();
    OutOutput.FileName = TEXT("tunnel_core_probe.csv");
    OutOutput.StepVoxels = 0.25f;
    const double StartSeconds = FPlatformTime::Seconds();

    if (!World.Manager.IsValid() || !World.Generator.IsValid()
        || !World.Settings.IsValid()
        || !World.Definitions.IsValidIndex(Arguments.Slot))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("The owner-value probe has no complete transient world.");
        return false;
    }

    const int32 TargetBottomChunkZ = FMath::FloorToInt(
        static_cast<float>(World.TargetBottomWorldZ) / static_cast<float>(CHUNK_SIZE));
    const int32 TargetTopChunkZ = FMath::FloorToInt(
        (static_cast<float>(World.TargetTopWorldZ) - KINDA_SMALL_NUMBER)
            / static_cast<float>(CHUNK_SIZE));
    const float TargetMinZ = static_cast<float>(World.TargetBottomWorldZ);
    const float TargetMaxZ = static_cast<float>(World.TargetTopWorldZ);
    constexpr float TargetBandPadding = 8.0f;
    constexpr float RouteParameterCheckStep = 4.0f;

    // The owner path asks GetGenerationParams for the exact (x,y,z) chunk of every sample. A
    // cache built from an arbitrary interior Z can therefore be a different graph in a boundary
    // blend band; that was the source of the earlier probe's FLT_MAX/core-only result. Build the
    // small set of candidate graphs used by the target Z chunks, and retain only a complete chain
    // whose route and radial measurement band resolve to the same parameter fingerprint that was
    // used to bake the graph. The field measured below is then the same field the game queries.
    auto GenerationParamsFingerprint = [](const FStrateGenerationParams& InParams) -> uint32
    {
        return FCrc::MemCrc32(&InParams, sizeof(InParams));
    };

    FChunkSDFCache Cache;
    FStrateGenerationParams Params;
    int32 StrateIndex = INDEX_NONE;
    int32 QueryChunkZ = INDEX_NONE;
    const FCachedTunnel* BestTunnel = nullptr;
    float BestLength = 0.0f;
    int32 BestTunnelIndex = INDEX_NONE;
    bool bBestTunnelFullyInTargetStrate = false;
    int32 BestTargetBandPointCount = 0;
    uint32 BestParamsFingerprint = 0xFFFFFFFFu;
    const uint32 WorldSeed = static_cast<uint32>(World.Settings->Seed);

    for (int32 CandidateChunkZ = TargetBottomChunkZ;
         CandidateChunkZ <= TargetTopChunkZ;
         ++CandidateChunkZ)
    {
        if (Budget.ShouldStop(TEXT("tunnel-core-probe-cache")))
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.RefusalReason = TEXT("The wall-clock budget stopped candidate cache construction.");
            OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
            return false;
        }

        const FIntVector CandidateChunk(0, 0, CandidateChunkZ);
        const FStrateGenerationParams CandidateParams =
            World.Manager->GetGenerationParams(CandidateChunk);
        const int32 CandidateStrateIndex = World.Manager->GetStrateIndex(
            (static_cast<float>(CandidateChunk.Z) + 0.5f)
                * static_cast<float>(CHUNK_SIZE) * VOXEL_SIZE);
        if (CandidateStrateIndex < 0
            || !(CandidateParams.RoomDensity > 0.0f)
            || !(CandidateParams.RoomSpacing > 0.0f))
        {
            continue;
        }

        const UVoxelStrateDefinition* CandidateDefinition =
            World.Manager->GetStrateForChunk(CandidateChunk);
        const TArray<FStrateTerrainOpEntry>* CandidateTerrainOps = CandidateDefinition != nullptr
            ? &CandidateDefinition->TerrainOperations : nullptr;
        const uint32 CandidateFingerprint = GenerationParamsFingerprint(CandidateParams);

        // The owner render region is centred near the origin. Keep each candidate cache broad
        // enough for the local graph, exactly like the ordinary point-query cache window.
        FChunkSDFCache CandidateCache;
        VoxelCaveMorphology::BuildChunkCache(
            CandidateCache, -256.0f, -256.0f, 256.0f, 256.0f,
            CandidateParams, WorldSeed, CandidateStrateIndex,
            CandidateTerrainOps, ERoomGraphBuildSite::GeneratorTunnelCore);

        int32 CandidateBestTunnelIndex = INDEX_NONE;
        float CandidateBestLength = 0.0f;
        int32 CandidateBestTargetSampleCount = 0;
        for (int32 TunnelIndex = 0; TunnelIndex < CandidateCache.Tunnels.Num(); ++TunnelIndex)
        {
            const FCachedTunnel& Tunnel = CandidateCache.Tunnels[TunnelIndex];
            const TArray<FVector>& Points = Tunnel.WorldControlPoints.Num() >= 2
                && Tunnel.WorldControlRadii.Num() == Tunnel.WorldControlPoints.Num()
                ? Tunnel.WorldControlPoints : Tunnel.ControlPoints;
            const TArray<float>& Radii = Tunnel.WorldControlRadii.Num() == Points.Num()
                ? Tunnel.WorldControlRadii : Tunnel.ControlRadii;
            if (Points.Num() < 2 || Radii.Num() != Points.Num())
            {
                continue;
            }

            TArray<float> CandidateCumulativeLengths;
            CandidateCumulativeLengths.SetNumZeroed(Points.Num());
            bool bFinite = true;
            float Length = 0.0f;
            float MaxRadius = 0.0f;
            for (int32 PointIndex = 0; PointIndex + 1 < Points.Num(); ++PointIndex)
            {
                const float SegmentLength = FVector::Dist(
                    Points[PointIndex], Points[PointIndex + 1]);
                if (!FMath::IsFinite(SegmentLength))
                {
                    bFinite = false;
                    break;
                }
                Length += SegmentLength;
                CandidateCumulativeLengths[PointIndex + 1] = Length;
                MaxRadius = FMath::Max(MaxRadius, FMath::Abs(Radii[PointIndex]));
            }
            if (Points.Num() > 0)
            {
                MaxRadius = FMath::Max(MaxRadius, FMath::Abs(Radii.Last()));
            }
            if (!bFinite || Length < 40.0f)
            {
                continue;
            }

            auto PointAtCandidateDistance = [&](float Distance) -> FVector
            {
                const float ClampedDistance = FMath::Clamp(Distance, 0.0f, Length);
                for (int32 SegmentIndex = 0;
                     SegmentIndex + 1 < Points.Num();
                     ++SegmentIndex)
                {
                    if (ClampedDistance <= CandidateCumulativeLengths[SegmentIndex + 1]
                        || SegmentIndex + 2 == Points.Num())
                    {
                        const float SegmentLength = CandidateCumulativeLengths[SegmentIndex + 1]
                            - CandidateCumulativeLengths[SegmentIndex];
                        const float Alpha = SegmentLength > KINDA_SMALL_NUMBER
                            ? (ClampedDistance - CandidateCumulativeLengths[SegmentIndex])
                                / SegmentLength : 0.0f;
                        return FMath::Lerp(Points[SegmentIndex], Points[SegmentIndex + 1], Alpha);
                    }
                }
                return Points.Last();
            };

            const float RadialParameterReach = FMath::Clamp(
                MaxRadius + 12.0f, 12.0f, 64.0f);
            bool bHasTargetSample = false;
            bool bRouteMatchesParams = true;
            int32 TargetSampleCount = 0;
            const int32 ParameterSampleCount = FMath::CeilToInt(
                Length / RouteParameterCheckStep);
            for (int32 SampleIndex = 0;
                 SampleIndex <= ParameterSampleCount;
                 ++SampleIndex)
            {
                const float Distance = FMath::Min(
                    Length, static_cast<float>(SampleIndex) * RouteParameterCheckStep);
                const FVector Point = PointAtCandidateDistance(Distance);
                const bool bInTargetBand = Point.Z >= TargetMinZ - TargetBandPadding
                    && Point.Z <= TargetMaxZ + TargetBandPadding;
                bHasTargetSample |= bInTargetBand;
                TargetSampleCount += bInTargetBand ? 1 : 0;
                if (!bInTargetBand)
                {
                    bRouteMatchesParams = false;
                    break;
                }

                const FIntVector PointChunk(
                    FMath::FloorToInt(Point.X / static_cast<float>(CHUNK_SIZE)),
                    FMath::FloorToInt(Point.Y / static_cast<float>(CHUNK_SIZE)),
                    FMath::FloorToInt(Point.Z / static_cast<float>(CHUNK_SIZE)));
                if (GenerationParamsFingerprint(
                        World.Manager->GetGenerationParams(PointChunk)) != CandidateFingerprint)
                {
                    bRouteMatchesParams = false;
                    break;
                }

                // The floor, wall and ceiling roots are measured around this same centerline.
                // Reject a route whose radial band crosses into a different parameter blend; a
                // single cache cannot represent that discontinuous query context.
                for (float RadialOffset = -RadialParameterReach;
                     RadialOffset <= RadialParameterReach + KINDA_SMALL_NUMBER;
                     RadialOffset += 8.0f)
                {
                    const FVector RadialPoint = Point + FVector(0.0f, 0.0f, RadialOffset);
                    const FIntVector RadialChunk(
                        FMath::FloorToInt(RadialPoint.X / static_cast<float>(CHUNK_SIZE)),
                        FMath::FloorToInt(RadialPoint.Y / static_cast<float>(CHUNK_SIZE)),
                        FMath::FloorToInt(RadialPoint.Z / static_cast<float>(CHUNK_SIZE)));
                    if (GenerationParamsFingerprint(
                            World.Manager->GetGenerationParams(RadialChunk))
                        != CandidateFingerprint)
                    {
                        bRouteMatchesParams = false;
                        break;
                    }
                }
                if (!bRouteMatchesParams)
                {
                    break;
                }
            }

            if (bHasTargetSample && bRouteMatchesParams
                && (TargetSampleCount > CandidateBestTargetSampleCount
                    || (TargetSampleCount == CandidateBestTargetSampleCount
                        && Length > CandidateBestLength)))
            {
                CandidateBestTunnelIndex = TunnelIndex;
                CandidateBestLength = Length;
                CandidateBestTargetSampleCount = TargetSampleCount;
            }
        }

        if (CandidateBestTunnelIndex != INDEX_NONE
            && CandidateBestLength > BestLength)
        {
            Cache = MoveTemp(CandidateCache);
            Params = CandidateParams;
            StrateIndex = CandidateStrateIndex;
            QueryChunkZ = CandidateChunkZ;
            BestLength = CandidateBestLength;
            BestTunnelIndex = CandidateBestTunnelIndex;
            BestTargetBandPointCount = CandidateBestTargetSampleCount;
            bBestTunnelFullyInTargetStrate = true;
            BestParamsFingerprint = CandidateFingerprint;
        }
    }

    BestTunnel = Cache.Tunnels.IsValidIndex(BestTunnelIndex)
        ? &Cache.Tunnels[BestTunnelIndex] : nullptr;
    if (BestTunnel == nullptr || BestLength < 40.0f)
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = FString::Printf(
            TEXT("No cached owner tunnel had a 40-voxel span with stable game params "
                 "and a stable radial band (best=%.3f)."), BestLength);
        OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
        return false;
    }

    const TArray<FVector>& Points = BestTunnel->WorldControlPoints.Num() >= 2
        && BestTunnel->WorldControlRadii.Num() == BestTunnel->WorldControlPoints.Num()
        ? BestTunnel->WorldControlPoints : BestTunnel->ControlPoints;
    TArray<float> CumulativeLengths;
    CumulativeLengths.SetNumZeroed(Points.Num());
    for (int32 PointIndex = 0; PointIndex + 1 < Points.Num(); ++PointIndex)
    {
        CumulativeLengths[PointIndex + 1] = CumulativeLengths[PointIndex]
            + FVector::Dist(Points[PointIndex], Points[PointIndex + 1]);
    }

    const float ProbeStep = OutOutput.StepVoxels;
    const int32 MaxProbeSamples = 4097;
    float ProbeStart = 0.0f;
    float ProbeLength = FMath::Min(
        BestLength, static_cast<float>(MaxProbeSamples - 1) * ProbeStep);

    auto PointAtDistance = [&](float Distance) -> FVector
    {
        const float ClampedDistance = FMath::Clamp(Distance, 0.0f, BestLength);
        for (int32 SegmentIndex = 0; SegmentIndex + 1 < Points.Num(); ++SegmentIndex)
        {
            if (ClampedDistance <= CumulativeLengths[SegmentIndex + 1]
                || SegmentIndex + 2 == Points.Num())
            {
                const float SegmentLength = CumulativeLengths[SegmentIndex + 1]
                    - CumulativeLengths[SegmentIndex];
                const float Alpha = SegmentLength > KINDA_SMALL_NUMBER
                    ? (ClampedDistance - CumulativeLengths[SegmentIndex]) / SegmentLength : 0.0f;
                return FMath::Lerp(Points[SegmentIndex], Points[SegmentIndex + 1], Alpha);
            }
        }
        return Points.Last();
    };

    // Keep a long, endpoint-inset window on the selected tunnel chain. The DFT is intended to
    // expose a repeated radial surface displacement, so using the entire wandering chain would
    // mix mouth overlap and changes in the local frame into that signal. The center window stays
    // on the same owner-parameter band already validated above and is at least 40 voxels long.
    const float MaximumWindowLength = static_cast<float>(MaxProbeSamples - 1) * ProbeStep;
    if (BestLength >= 56.0f)
    {
        ProbeLength = FMath::Min(96.0f, FMath::Min(BestLength - 16.0f, MaximumWindowLength));
        if (ProbeLength >= 40.0f)
        {
            ProbeStart = FMath::Clamp(
                (BestLength - ProbeLength) * 0.5f, 8.0f, BestLength - ProbeLength - 8.0f);
        }
    }
    if (ProbeStart + ProbeLength > BestLength)
    {
        ProbeStart = 0.0f;
        ProbeLength = FMath::Min(BestLength, MaximumWindowLength);
    }
    const int32 SampleCount = FMath::FloorToInt(ProbeLength / ProbeStep) + 1;
    ProbeLength = static_cast<float>(SampleCount - 1) * ProbeStep;
    OutOutput.TunnelIndex = BestTunnelIndex;
    OutOutput.SampleCount = SampleCount;
    OutOutput.LengthVoxels = ProbeLength;

    FVector AxisDirection = PointAtDistance(ProbeStart + ProbeLength)
        - PointAtDistance(ProbeStart);
    AxisDirection.Z = 0.0f;
    if (!AxisDirection.Normalize())
    {
        float LongestSegment = 0.0f;
        for (int32 SegmentIndex = 0; SegmentIndex + 1 < Points.Num(); ++SegmentIndex)
        {
            FVector Candidate = Points[SegmentIndex + 1] - Points[SegmentIndex];
            Candidate.Z = 0.0f;
            const float SegmentLength = Candidate.Size();
            if (SegmentLength > LongestSegment)
            {
                LongestSegment = SegmentLength;
                AxisDirection = Candidate / SegmentLength;
            }
        }
    }
    if (!AxisDirection.Normalize())
    {
        AxisDirection = FVector::ForwardVector;
    }
    const FVector WallDirection(-AxisDirection.Y, AxisDirection.X, 0.0f);
    OutOutput.AxisStart = PointAtDistance(ProbeStart);
    OutOutput.AxisEnd = PointAtDistance(ProbeStart + ProbeLength);
    OutOutput.AxisDirection = AxisDirection;
    OutOutput.WallDirection = WallDirection;

    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeTunnelCoreProbe] cache_tunnels=%d strate_index=%d "
             "query_chunk_z=%d target_z=[%.3f,%.3f] params_z=[%.3f,%.3f] selected=%d "
             "params_fp=0x%08X window_start=%.3f window_length=%.3f "
             "selected_fully_in_target=%d target_points=%d"),
        Cache.Tunnels.Num(), StrateIndex, QueryChunkZ, TargetMinZ, TargetMaxZ,
        Params.StrateBottomWorldZ, Params.StrateTopWorldZ, BestTunnelIndex,
        BestParamsFingerprint, ProbeStart, ProbeLength,
        bBestTunnelFullyInTargetStrate ? 1 : 0, BestTargetBandPointCount);
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeTunnelCoreProbe] selected_endpoints a=(%.3f,%.3f,%.3f) "
             "b=(%.3f,%.3f,%.3f) world_min=(%.3f,%.3f,%.3f) "
             "world_max=(%.3f,%.3f,%.3f) world_radius=%.3f"),
        BestTunnel->EndpointA.X, BestTunnel->EndpointA.Y, BestTunnel->EndpointA.Z,
        BestTunnel->EndpointB.X, BestTunnel->EndpointB.Y, BestTunnel->EndpointB.Z,
        BestTunnel->WorldCenterlineMin.X, BestTunnel->WorldCenterlineMin.Y,
        BestTunnel->WorldCenterlineMin.Z, BestTunnel->WorldCenterlineMax.X,
        BestTunnel->WorldCenterlineMax.Y, BestTunnel->WorldCenterlineMax.Z,
        FMath::Sqrt(FMath::Max(BestTunnel->WorldBoundRadiusSq, 0.0f)));

    float MaxRadius = 0.0f;
    const TArray<float>& Radii = BestTunnel->WorldControlRadii.Num() == Points.Num()
        ? BestTunnel->WorldControlRadii : BestTunnel->ControlRadii;
    for (const float Radius : Radii)
    {
        MaxRadius = FMath::Max(MaxRadius, FMath::Abs(Radius));
    }
    const float MaxRadialDistance = FMath::Clamp(MaxRadius + 12.0f, 12.0f, 64.0f);

    auto FindZeroCrossing = [&](const FVector& Origin, const FVector& Direction,
                                bool bCoreSDF, float& OutDistance) -> bool
    {
        auto Evaluate = [&](float Distance) -> float
        {
            const FVector Position = Origin + Direction * Distance;
            return bCoreSDF
                ? VoxelCaveMorphology::EvaluateTunnelCoreWorldSDF(
                    Position.X, Position.Y, Position.Z, Cache, true)
                : World.Generator->GetDensityAt(Position.X, Position.Y, Position.Z);
        };
        float PreviousDistance = 0.0f;
        float PreviousValue = Evaluate(0.0f);
        bool bHavePrevious = FMath::IsFinite(PreviousValue);
        if (bHavePrevious && FMath::Abs(PreviousValue) <= 1.0e-4f)
        {
            OutDistance = 0.0f;
            return true;
        }
        const int32 RadialSteps = FMath::CeilToInt(MaxRadialDistance / ProbeStep);
        for (int32 StepIndex = 1; StepIndex <= RadialSteps; ++StepIndex)
        {
            const float CurrentDistance = FMath::Min(
                MaxRadialDistance, static_cast<float>(StepIndex) * ProbeStep);
            const float CurrentValue = Evaluate(CurrentDistance);
            if (!FMath::IsFinite(CurrentValue))
            {
                // A transient invalid query must split the finite run, not poison every
                // subsequent sample.  The floor ray can cross a chunk/parameter seam where
                // one exact fractional query is unavailable; later finite samples still form a
                // valid zero-crossing interval and are deliberately allowed to restart it.
                bHavePrevious = false;
                continue;
            }
            if (!bHavePrevious)
            {
                PreviousDistance = CurrentDistance;
                PreviousValue = CurrentValue;
                bHavePrevious = true;
                if (FMath::Abs(CurrentValue) <= 1.0e-4f)
                {
                    OutDistance = CurrentDistance;
                    return true;
                }
                continue;
            }
            const bool bCrossed = (PreviousValue < 0.0f && CurrentValue >= 0.0f)
                || (PreviousValue > 0.0f && CurrentValue <= 0.0f);
            if (bCrossed)
            {
                float Low = PreviousDistance;
                float High = CurrentDistance;
                float LowValue = PreviousValue;
                for (int32 Iteration = 0; Iteration < 24; ++Iteration)
                {
                    const float Mid = (Low + High) * 0.5f;
                    const float MidValue = Evaluate(Mid);
                    if (!FMath::IsFinite(MidValue))
                    {
                        break;
                    }
                    if (FMath::Abs(MidValue) <= 1.0e-5f)
                    {
                        Low = Mid;
                        High = Mid;
                        break;
                    }
                    if ((LowValue < 0.0f && MidValue < 0.0f)
                        || (LowValue > 0.0f && MidValue > 0.0f))
                    {
                        Low = Mid;
                        LowValue = MidValue;
                    }
                    else
                    {
                        High = Mid;
                    }
                }
                OutDistance = (Low + High) * 0.5f;
                return true;
            }
            PreviousDistance = CurrentDistance;
            PreviousValue = CurrentValue;
        }
        return false;
    };

    OutOutput.Floor.Name = TEXT("floor");
    OutOutput.Wall.Name = TEXT("wall");
    OutOutput.Ceiling.Name = TEXT("ceiling");
    OutOutput.Floor.CoreCrossingsVoxels.Reserve(SampleCount);
    OutOutput.Floor.FinalCrossingsVoxels.Reserve(SampleCount);
    OutOutput.Wall.CoreCrossingsVoxels.Reserve(SampleCount);
    OutOutput.Wall.FinalCrossingsVoxels.Reserve(SampleCount);
    OutOutput.Ceiling.CoreCrossingsVoxels.Reserve(SampleCount);
    OutOutput.Ceiling.FinalCrossingsVoxels.Reserve(SampleCount);

    FString Csv;
    Csv.Reserve(SampleCount * 180);
    Csv += TEXT("sample,axis_distance_voxels,center_x,center_y,center_z,core_center_sdf,final_center_density,"
                "floor_core_zero,floor_final_zero,wall_core_zero,wall_final_zero,"
                "ceiling_core_zero,ceiling_final_zero\r\n");
    float PreviousCoreCenter = 0.0f;
    float PreviousFinalCenter = 0.0f;
    bool bHavePreviousCoreCenter = false;
    bool bHavePreviousFinalCenter = false;
    float MaxGeneratorCoreDelta = 0.0f;
    int32 GeneratorCoreMismatchCount = 0;
    const uint32 ProbeLayoutVersion = World.Manager->GetLayoutVersion();
    for (int32 SampleIndex = 0; SampleIndex < SampleCount; ++SampleIndex)
    {
        if ((SampleIndex & 127) == 0 && Budget.ShouldStop(TEXT("tunnel-core-probe")))
        {
            OutOutput.Status = TEXT("truncated");
            OutOutput.RefusalReason = TEXT("The wall-clock budget stopped the tunnel-core probe.");
            OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
            return false;
        }
        const float AxisDistance = static_cast<float>(SampleIndex) * ProbeStep;
        const FVector Center = PointAtDistance(ProbeStart + AxisDistance);
        const float CoreCenter = VoxelCaveMorphology::EvaluateTunnelCoreWorldSDF(
            Center.X, Center.Y, Center.Z, Cache, true);
        const float FinalCenter = World.Generator->GetDensityAt(Center.X, Center.Y, Center.Z);
        FTunnelCoreWorldEvaluation GeneratorCoreEvaluation;
        World.Generator->GetDensityWithParams(
            Center.X, Center.Y, Center.Z, Params, BestParamsFingerprint, ProbeLayoutVersion,
            /*bApplyLegacyStructuralPosts=*/false, &GeneratorCoreEvaluation,
            /*bCollectFusedDiagnostics=*/false);
        if (FMath::IsFinite(CoreCenter) && FMath::IsFinite(GeneratorCoreEvaluation.SDF))
        {
            const float CoreDelta = FMath::Abs(CoreCenter - GeneratorCoreEvaluation.SDF);
            MaxGeneratorCoreDelta = FMath::Max(MaxGeneratorCoreDelta, CoreDelta);
            if (CoreDelta > 1.0e-3f)
            {
                ++GeneratorCoreMismatchCount;
            }
        }
        if (SampleIndex == 0 || SampleIndex == SampleCount / 2 || SampleIndex + 1 == SampleCount)
        {
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeTunnelCoreProbe] generator_core_compare sample=%d "
                     "probe_sdf=%.6g generator_sdf=%.6g generator_mc=%.6g final_mc=%.6g"),
                SampleIndex, CoreCenter, GeneratorCoreEvaluation.SDF,
                -GeneratorCoreEvaluation.SDF, FinalCenter);
        }
        if (FMath::IsFinite(CoreCenter))
        {
            ++OutOutput.CoreCenterFiniteSampleCount;
            OutOutput.CoreCenterMin = OutOutput.CoreCenterFiniteSampleCount == 1
                ? CoreCenter : FMath::Min(OutOutput.CoreCenterMin, CoreCenter);
            OutOutput.CoreCenterMax = OutOutput.CoreCenterFiniteSampleCount == 1
                ? CoreCenter : FMath::Max(OutOutput.CoreCenterMax, CoreCenter);
            if (bHavePreviousCoreCenter
                && ((PreviousCoreCenter < 0.0f && CoreCenter > 0.0f)
                    || (PreviousCoreCenter > 0.0f && CoreCenter < 0.0f)))
            {
                ++OutOutput.CoreCenterZeroCrossingCount;
            }
            PreviousCoreCenter = CoreCenter;
            bHavePreviousCoreCenter = true;
        }
        if (FMath::IsFinite(FinalCenter))
        {
            ++OutOutput.FinalCenterFiniteSampleCount;
            OutOutput.FinalCenterMin = OutOutput.FinalCenterFiniteSampleCount == 1
                ? FinalCenter : FMath::Min(OutOutput.FinalCenterMin, FinalCenter);
            OutOutput.FinalCenterMax = OutOutput.FinalCenterFiniteSampleCount == 1
                ? FinalCenter : FMath::Max(OutOutput.FinalCenterMax, FinalCenter);
            OutOutput.FinalCenterMaxAbs = FMath::Max(
                OutOutput.FinalCenterMaxAbs, FMath::Abs(FinalCenter));
            // The old hand-off wrote a fixed MC-air value (normally +16, with the reciprocal
            // solid plateau at -8 in other definitions).  Do not call every ordinary SDF sample
            // "saturated"; count only the known clamp plateaus so the probe distinguishes the
            // old hard switch from the continuous signed field.
            const bool bKnownClampPlateau =
                FMath::Abs(FinalCenter - 8.0f) <= 1.0e-3f
                || FMath::Abs(FinalCenter + 8.0f) <= 1.0e-3f
                || FMath::Abs(FinalCenter - 16.0f) <= 1.0e-3f
                || FMath::Abs(FinalCenter + 16.0f) <= 1.0e-3f;
            if (bKnownClampPlateau)
            {
                ++OutOutput.FinalCenterSaturatedSampleCount;
            }
            if (bHavePreviousFinalCenter
                && ((PreviousFinalCenter < 0.0f && FinalCenter > 0.0f)
                    || (PreviousFinalCenter > 0.0f && FinalCenter < 0.0f)))
            {
                ++OutOutput.FinalCenterZeroCrossingCount;
            }
            PreviousFinalCenter = FinalCenter;
            bHavePreviousFinalCenter = true;
        }

        const FVector RadialDirections[3] = {
            FVector::DownVector, WallDirection, FVector::UpVector };
        FExploreTunnelCoreProbeAxis* Axes[3] = {
            &OutOutput.Floor, &OutOutput.Wall, &OutOutput.Ceiling };
        float Roots[3][2];
        for (int32 AxisIndex = 0; AxisIndex < 3; ++AxisIndex)
        {
            Roots[AxisIndex][0] = std::numeric_limits<float>::quiet_NaN();
            Roots[AxisIndex][1] = std::numeric_limits<float>::quiet_NaN();
            FindZeroCrossing(Center, RadialDirections[AxisIndex], true, Roots[AxisIndex][0]);
            FindZeroCrossing(Center, RadialDirections[AxisIndex], false, Roots[AxisIndex][1]);
            Axes[AxisIndex]->CoreCrossingsVoxels.Add(Roots[AxisIndex][0]);
            Axes[AxisIndex]->FinalCrossingsVoxels.Add(Roots[AxisIndex][1]);
        }
        if (SampleIndex == 50 || SampleIndex == 302)
        {
            const float DiagnosticDistances[] = { 0.0f, 4.0f, 8.0f, 10.0f, 11.0f,
                12.0f, 13.0f, 16.0f, 20.0f, 24.0f, 28.0f, 32.0f };
            for (int32 AxisIndex = 0; AxisIndex < 3; ++AxisIndex)
            {
                FString Values;
                for (const float Distance : DiagnosticDistances)
                {
                    const FVector Position = Center + RadialDirections[AxisIndex] * Distance;
                    const float CoreValue = VoxelCaveMorphology::EvaluateTunnelCoreWorldSDF(
                        Position.X, Position.Y, Position.Z, Cache, true);
                    FTunnelCoreWorldEvaluation GenericCoreEvaluation;
                    const float GenericValue = World.Generator->GetDensityWithParams(
                        Position.X, Position.Y, Position.Z, Params, BestParamsFingerprint,
                        ProbeLayoutVersion, /*bApplyLegacyStructuralPosts=*/false,
                        &GenericCoreEvaluation, /*bCollectFusedDiagnostics=*/false);
                    const float FinalValue = World.Generator->GetDensityAt(
                        Position.X, Position.Y, Position.Z);
                    Values += FString::Printf(
                        TEXT(" %.0f:(%.3g,%.3g,%.3g)"), Distance, CoreValue,
                        GenericValue, FinalValue);
                }
                UE_LOG(LogTemp, Display,
                    TEXT("[VoxelForgeTunnelCoreProbe] radial_diagnostic sample=%d axis=%s "
                         "distance:(core_sdf,generic_mc,final_mc)%s"),
                    SampleIndex, *Axes[AxisIndex]->Name, *Values);
            }
        }
        Csv += FString::Printf(
            TEXT("%d,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g,%.9g\r\n"),
            SampleIndex, AxisDistance, Center.X, Center.Y, Center.Z,
            CoreCenter, FinalCenter,
            Roots[0][0], Roots[0][1], Roots[1][0], Roots[1][1], Roots[2][0], Roots[2][1]);
    }

    FExploreTunnelCoreProbeAxis* Axes[3] = {
        &OutOutput.Floor, &OutOutput.Wall, &OutOutput.Ceiling };
    for (FExploreTunnelCoreProbeAxis* Axis : Axes)
    {
        ComputeTunnelCoreProbeMetrics(
            Axis->CoreCrossingsVoxels, ProbeStep,
            Axis->ValidCoreCrossings, Axis->CoreMeanCrossingVoxels,
            Axis->CoreMinCrossingVoxels, Axis->CoreMaxCrossingVoxels,
            Axis->CorePeriodicAmplitudeVoxels, Axis->CorePeriodicPeriodVoxels,
            Axis->CorePeriodicMeasuredSamples, Axis->CorePeriodicMeasuredLengthVoxels);
        ComputeTunnelCoreProbeMetrics(
            Axis->FinalCrossingsVoxels, ProbeStep,
            Axis->ValidFinalCrossings, Axis->FinalMeanCrossingVoxels,
            Axis->FinalMinCrossingVoxels, Axis->FinalMaxCrossingVoxels,
            Axis->FinalPeriodicAmplitudeVoxels, Axis->FinalPeriodicPeriodVoxels,
            Axis->FinalPeriodicMeasuredSamples, Axis->FinalPeriodicMeasuredLengthVoxels);
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeTunnelCoreProbe] axis=%s samples=%d final_valid=%d "
                 "rib_periodic_amplitude=%.6g_voxels=%.6g_cm period=%.6g_voxels "
                 "measured=%.6g_voxels/%d core_valid=%d core_rib_periodic_amplitude=%.6g_voxels=%.6g_cm period=%.6g_voxels "
                 "measured=%.6g_voxels/%d"),
            *Axis->Name, SampleCount, Axis->ValidFinalCrossings,
            Axis->FinalPeriodicAmplitudeVoxels,
            Axis->FinalPeriodicAmplitudeVoxels * 25.0f,
            Axis->FinalPeriodicPeriodVoxels,
            Axis->FinalPeriodicMeasuredLengthVoxels, Axis->FinalPeriodicMeasuredSamples,
            Axis->ValidCoreCrossings, Axis->CorePeriodicAmplitudeVoxels,
            Axis->CorePeriodicAmplitudeVoxels * 25.0f,
            Axis->CorePeriodicPeriodVoxels,
             Axis->CorePeriodicMeasuredLengthVoxels, Axis->CorePeriodicMeasuredSamples);
    }

    // Mouth probe: measure the two surfaces that meet at each room endpoint over a lateral
    // window of approximately +/-2 tunnel radii.  The wall ray starts in room air and points
    // toward the tunnel; the floor ray starts below the same room-side patch and points up.
    // Both use the final MC-facing density, so this catches a ring/fillet handoff rather than
    // merely comparing two independent source SDFs.  Keep this in the same owner-value process
    // and cache selection as the core probe so the before/after numbers are directly comparable.
    {
        FExploreTunnelMouthProbeOutput& Mouth = OutOutput.Mouth;
        Mouth = FExploreTunnelMouthProbeOutput();
        Mouth.FileName = TEXT("tunnel_mouth_probe.csv");
        const double MouthStartSeconds = FPlatformTime::Seconds();
        FString MouthCsv;
        MouthCsv.Reserve(8192);
        MouthCsv += TEXT(
            "endpoint,lateral_offset_voxels,wall_surface_distance_voxels,"
            "floor_surface_height_voxels\r\n");

        const TArray<float>& MouthRadii = Radii;
        const TArray<FVector>& MouthPoints = Points;
        const int32 MouthPointCount = MouthPoints.Num();
        const uint32 RoomHashes[2] = {
            BestTunnel->FloorRoomHashA, BestTunnel->FloorRoomHashB };
        const int32 EndpointPointIndices[2] = { 0, MouthPointCount - 1 };
        const int32 InteriorPointIndices[2] = { 1, MouthPointCount - 2 };
        TSet<uint32> CountedRoomHashes;

        auto CachedRoomRawSDF = [](const FCachedRoom& Room, const FVector& Position) -> float
        {
            switch (Room.ShapeType)
            {
            case 1:
                return VoxelSDF::RoundedBox(
                    Position, Room.Center, Room.ShapeA, Room.ShapeR);
            case 2:
                return VoxelSDF::Capsule(
                    Position, Room.ShapeA, Room.ShapeB, Room.ShapeR);
            default:
                return VoxelSDF::Ellipsoid(Position, Room.Center, Room.ShapeA);
            }
        };

        // The room-volume attribution sample is intentionally coarser than the mesh lattice. It
        // is a count instrument, not a replacement for the matched export, and its resolution is
        // recorded in the report. A core-induced solid must still be zero at this resolution.
        const int32 RoomSampleStep = Mouth.RoomSampleStepVoxels;
        for (int32 EndpointIndex = 0; EndpointIndex < 2; ++EndpointIndex)
        {
            const int32 PointIndex = EndpointPointIndices[EndpointIndex];
            const int32 InteriorIndex = InteriorPointIndices[EndpointIndex];
            if (!MouthPoints.IsValidIndex(PointIndex)
                || !MouthPoints.IsValidIndex(InteriorIndex)
                || !MouthRadii.IsValidIndex(PointIndex))
            {
                continue;
            }

            FExploreTunnelMouthProbeEndpoint& Endpoint = Mouth.Endpoints.AddDefaulted_GetRef();
            Endpoint.Name = EndpointIndex == 0 ? TEXT("A") : TEXT("B");
            Endpoint.RoomHash = RoomHashes[EndpointIndex];
            Endpoint.Mouth = MouthPoints[PointIndex];
            Endpoint.RadiusVoxels = FMath::Abs(MouthRadii[PointIndex]);
            Endpoint.TunnelFloorZ = EndpointIndex == 0
                ? BestTunnel->WorldMouthFloorZA : BestTunnel->WorldMouthFloorZB;
            if (!FMath::IsFinite(Endpoint.TunnelFloorZ))
            {
                Endpoint.TunnelFloorZ = static_cast<float>(Endpoint.Mouth.Z)
                    - Endpoint.RadiusVoxels;
            }

            FVector RoomToTunnel = MouthPoints[InteriorIndex] - MouthPoints[PointIndex];
            RoomToTunnel.Z = 0.0f;
            if (!RoomToTunnel.Normalize())
            {
                RoomToTunnel = EndpointIndex == 0
                    ? FVector::ForwardVector : -FVector::ForwardVector;
            }
            const FVector Lateral(-RoomToTunnel.Y, RoomToTunnel.X, 0.0f);
            const float MaxMouthRadius = FMath::Max(MaxRadius, Endpoint.RadiusVoxels);
            const float MouthRayReach = FMath::Max(MaxMouthRadius + 12.0f, 16.0f);
            const float LateralHalfWidth = FMath::Max(
                Endpoint.RadiusVoxels * 2.0f, 8.0f);
            const float LateralStep = 0.25f;
            const int32 LateralSamples = FMath::Max(
                5, FMath::FloorToInt(
                    (2.0f * LateralHalfWidth) / LateralStep) + 1);
            const float ActualHalfWidth =
                0.5f * static_cast<float>(LateralSamples - 1) * LateralStep;
            Mouth.LateralSampleCount = FMath::Max(Mouth.LateralSampleCount, LateralSamples);
            Mouth.LateralWindowVoxels = FMath::Max(
                Mouth.LateralWindowVoxels, 2.0f * ActualHalfWidth);

            Endpoint.Wall.Name = TEXT("wall");
            Endpoint.Floor.Name = TEXT("floor");
            Endpoint.Wall.CrossingsVoxels.Reserve(LateralSamples);
            Endpoint.Floor.CrossingsVoxels.Reserve(LateralSamples);

            // Keep the origin in finite room air but close enough that the existing radial
            // crossing search still reaches the mouth in one probe window.
            const float WallInteriorDepth = FMath::Min(
                FMath::Max(4.0f * Endpoint.RadiusVoxels, 12.0f),
                0.5f * MouthRayReach);
            const float FloorInteriorDepth = FMath::Min(
                FMath::Max(Endpoint.RadiusVoxels, 4.0f),
                0.25f * MouthRayReach);
            const float FloorOriginZ = static_cast<float>(Endpoint.Mouth.Z)
                - Endpoint.RadiusVoxels - 8.0f;

            for (int32 SampleIndex = 0; SampleIndex < LateralSamples; ++SampleIndex)
            {
                const float LateralOffset = -ActualHalfWidth
                    + static_cast<float>(SampleIndex) * LateralStep;
                const FVector LateralOffsetVector = Lateral * LateralOffset;
                const FVector WallOrigin = Endpoint.Mouth + LateralOffsetVector
                    - RoomToTunnel * WallInteriorDepth;
                const FVector FloorOrigin(
                    Endpoint.Mouth.X + LateralOffsetVector.X
                        - RoomToTunnel.X * FloorInteriorDepth,
                    Endpoint.Mouth.Y + LateralOffsetVector.Y
                        - RoomToTunnel.Y * FloorInteriorDepth,
                    FloorOriginZ);
                float WallCrossing = std::numeric_limits<float>::quiet_NaN();
                float FloorCrossing = std::numeric_limits<float>::quiet_NaN();
                FindZeroCrossing(
                    WallOrigin, RoomToTunnel, false, WallCrossing);
                FindZeroCrossing(
                    FloorOrigin, FVector::UpVector, false, FloorCrossing);
                Endpoint.Wall.CrossingsVoxels.Add(WallCrossing);
                Endpoint.Floor.CrossingsVoxels.Add(FloorCrossing);
                MouthCsv += FString::Printf(
                    TEXT("%s,%.9g,%.9g,%.9g\r\n"),
                    *Endpoint.Name, LateralOffset, WallCrossing, FloorCrossing);
            }

            ComputeTunnelMouthProbeMetrics(Endpoint.Wall, LateralStep);
            ComputeTunnelMouthProbeMetrics(Endpoint.Floor, LateralStep);
            Mouth.MaxWallPeriodicAmplitudeVoxels = FMath::Max(
                Mouth.MaxWallPeriodicAmplitudeVoxels,
                Endpoint.Wall.PeriodicAmplitudeVoxels);
            Mouth.MaxFloorPeriodicAmplitudeVoxels = FMath::Max(
                Mouth.MaxFloorPeriodicAmplitudeVoxels,
                Endpoint.Floor.PeriodicAmplitudeVoxels);
            Mouth.MaxLocalMedianWallPeriodicAmplitudeVoxels = FMath::Max(
                Mouth.MaxLocalMedianWallPeriodicAmplitudeVoxels,
                Endpoint.Wall.LocalMedianPeriodicAmplitudeVoxels);
            Mouth.MaxLocalMedianFloorPeriodicAmplitudeVoxels = FMath::Max(
                Mouth.MaxLocalMedianFloorPeriodicAmplitudeVoxels,
                Endpoint.Floor.LocalMedianPeriodicAmplitudeVoxels);

            const int32 CentreIndex = LateralSamples / 2;
            if (Endpoint.Floor.CrossingsVoxels.IsValidIndex(CentreIndex)
                && FMath::IsFinite(Endpoint.Floor.CrossingsVoxels[CentreIndex]))
            {
                Endpoint.RoomFloorCrossingZ = FloorOriginZ
                    + Endpoint.Floor.CrossingsVoxels[CentreIndex];
                Endpoint.FloorJoinDeltaVoxels = Endpoint.RoomFloorCrossingZ
                    - Endpoint.TunnelFloorZ;
            }

            // Count the room-volume samples once per endpoint room. This catches the exact
            // failure mode from the screenshot: the generic field is air, then the tunnel-core
            // bottom post changes it back to solid inside a room.
            const FCachedRoom* Room = nullptr;
            for (const FCachedRoom& CandidateRoom : Cache.Rooms)
            {
                if (CandidateRoom.Hash == RoomHashes[EndpointIndex])
                {
                    Room = &CandidateRoom;
                    break;
                }
            }
            if (Room == nullptr || CountedRoomHashes.Contains(Room->Hash))
            {
                continue;
            }
            CountedRoomHashes.Add(Room->Hash);

            FVector ShapeExtentVector(
                FMath::Abs(Room->ShapeA.X),
                FMath::Abs(Room->ShapeA.Y),
                FMath::Abs(Room->ShapeA.Z));
            if (Room->ShapeType == 2)
            {
                ShapeExtentVector = FVector(
                    FMath::Max(
                        FMath::Abs(Room->ShapeA.X - Room->Center.X),
                        FMath::Abs(Room->ShapeB.X - Room->Center.X)),
                    FMath::Max(
                        FMath::Abs(Room->ShapeA.Y - Room->Center.Y),
                        FMath::Abs(Room->ShapeB.Y - Room->Center.Y)),
                    FMath::Max(
                        FMath::Abs(Room->ShapeA.Z - Room->Center.Z),
                        FMath::Abs(Room->ShapeB.Z - Room->Center.Z)));
            }
            const float ShapeExtent = FMath::Max3(
                ShapeExtentVector.X, ShapeExtentVector.Y, ShapeExtentVector.Z)
                + FMath::Abs(Room->ShapeR) + 2.0f;
            const int32 MinX = FMath::FloorToInt(Room->Center.X - ShapeExtent);
            const int32 MinY = FMath::FloorToInt(Room->Center.Y - ShapeExtent);
            const int32 MinZ = FMath::FloorToInt(Room->Center.Z - ShapeExtent);
            const int32 MaxX = FMath::CeilToInt(Room->Center.X + ShapeExtent);
            const int32 MaxY = FMath::CeilToInt(Room->Center.Y + ShapeExtent);
            const int32 MaxZ = FMath::CeilToInt(Room->Center.Z + ShapeExtent);
            for (int32 Z = MinZ; Z <= MaxZ; Z += RoomSampleStep)
            {
                for (int32 Y = MinY; Y <= MaxY; Y += RoomSampleStep)
                {
                    for (int32 X = MinX; X <= MaxX; X += RoomSampleStep)
                    {
                        const FVector Position(
                            static_cast<float>(X), static_cast<float>(Y), static_cast<float>(Z));
                        if (!(CachedRoomRawSDF(*Room, Position) < 0.0f))
                        {
                            continue;
                        }
                        ++Mouth.RoomVolumeSampleCount;

                        FTunnelCoreWorldEvaluation CoreEvaluation;
                        const float GenericDensity = World.Generator->GetDensityWithParams(
                            Position.X, Position.Y, Position.Z,
                            Params, BestParamsFingerprint, ProbeLayoutVersion,
                            /*bApplyLegacyStructuralPosts=*/false,
                            &CoreEvaluation,
                            /*bCollectFusedDiagnostics=*/false);
                        const float FinalDensity = World.Generator->GetDensityAt(
                            Position.X, Position.Y, Position.Z);
                        if (!FMath::IsFinite(GenericDensity)
                            || !FMath::IsFinite(FinalDensity))
                        {
                            continue;
                        }
                        if (GenericDensity > 0.0f)
                        {
                            ++Mouth.RoomAirSampleCount;
                        }
                        if (FinalDensity <= 0.0f)
                        {
                            ++Mouth.FinalSolidSampleCount;
                        }
                        const bool bOwnsSweptBottom =
                            CoreEvaluation.bHasSweptFloor
                            && FMath::IsFinite(CoreEvaluation.SweptFloorZ)
                            && FMath::IsFinite(CoreEvaluation.SweptFloorRadius)
                            && Position.Z <= CoreEvaluation.SweptFloorZ
                                + VoxelPassageGeometry::WalkableTunnelFloorAirClearanceVoxels;
                        if (bOwnsSweptBottom)
                        {
                            ++Mouth.CoreBottomSampleCount;
                            if (GenericDensity > 0.0f && FinalDensity <= 0.0f)
                            {
                                ++Mouth.CoreInducedSolidSampleCount;
                            }
                        }
                    }
                }
            }
        }

        Mouth.EndpointCount = Mouth.Endpoints.Num();
        const FString MouthPath = FPaths::Combine(Arguments.OutDirectory, Mouth.FileName);
        if (!FFileHelper::SaveStringToFile(
                MouthCsv, *MouthPath, FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
        {
            Mouth.Status = TEXT("error");
            Mouth.RefusalReason = TEXT("Could not write tunnel_mouth_probe.csv.");
        }
        else if (Mouth.EndpointCount < 2)
        {
            Mouth.Status = TEXT("error");
            Mouth.RefusalReason = TEXT("The selected tunnel did not expose two room endpoints.");
        }
        else
        {
            Mouth.Status = TEXT("ok");
        }
        Mouth.Seconds = FPlatformTime::Seconds() - MouthStartSeconds;
        UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeTunnelMouthProbe] endpoints=%d room_samples=%lld room_air=%lld "
             "core_bottom=%lld final_solid=%lld core_induced_solid=%lld "
             "wall_periodic=%.6g_voxels=%.6g_cm floor_periodic=%.6g_voxels=%.6g_cm "
             "legacy_floor_periodic=%.6g_voxels=%.6g_cm "
             "lateral_window=%.3f step=%.3f file=%s"),
            Mouth.EndpointCount,
            Mouth.RoomVolumeSampleCount, Mouth.RoomAirSampleCount,
            Mouth.CoreBottomSampleCount, Mouth.FinalSolidSampleCount,
            Mouth.CoreInducedSolidSampleCount,
            Mouth.MaxWallPeriodicAmplitudeVoxels,
             Mouth.MaxWallPeriodicAmplitudeVoxels * 25.0f,
             Mouth.MaxFloorPeriodicAmplitudeVoxels,
             Mouth.MaxFloorPeriodicAmplitudeVoxels * 25.0f,
             Mouth.MaxLocalMedianFloorPeriodicAmplitudeVoxels,
             Mouth.MaxLocalMedianFloorPeriodicAmplitudeVoxels * 25.0f,
             Mouth.LateralWindowVoxels, Mouth.LateralStepVoxels, *MouthPath);
    }

    const FString Path = FPaths::Combine(Arguments.OutDirectory, OutOutput.FileName);
    if (!FFileHelper::SaveStringToFile(
            Csv, *Path, FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        OutOutput.Status = TEXT("error");
        OutOutput.RefusalReason = TEXT("Could not write tunnel_core_probe.csv.");
        OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
        return false;
    }
    OutOutput.Status = TEXT("ok");
    OutOutput.Seconds = FPlatformTime::Seconds() - StartSeconds;
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeTunnelCoreProbe] tunnel=%d samples=%d step=%.3f length=%.3f "
             "final_center_finite=%d known_clamp_plateau=%d range=[%.6g,%.6g] "
             "core_center_finite=%d range=[%.6g,%.6g] file=%s"),
        OutOutput.TunnelIndex, OutOutput.SampleCount, OutOutput.StepVoxels,
             OutOutput.LengthVoxels, OutOutput.FinalCenterFiniteSampleCount,
             OutOutput.FinalCenterSaturatedSampleCount, OutOutput.FinalCenterMin,
             OutOutput.FinalCenterMax, OutOutput.CoreCenterFiniteSampleCount,
             OutOutput.CoreCenterMin, OutOutput.CoreCenterMax, *Path);
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeTunnelCoreProbe] generator_core_compare_max_abs_delta=%.6g "
             "mismatched_samples=%d tolerance=0.001"),
        MaxGeneratorCoreDelta, GeneratorCoreMismatchCount);
    return true;
}

void WriteTunnelCoreProbeAxis(
    FExploreJsonWriter& Writer,
    const FExploreTunnelCoreProbeAxis& Axis,
    const TCHAR* Key)
{
    Writer.WriteObjectStart(Key);
    Writer.WriteValue(TEXT("valid_core_crossings"), Axis.ValidCoreCrossings);
    Writer.WriteValue(TEXT("valid_final_crossings"), Axis.ValidFinalCrossings);
    Writer.WriteValue(TEXT("core_mean_crossing_voxels"), static_cast<double>(Axis.CoreMeanCrossingVoxels));
    Writer.WriteValue(TEXT("final_mean_crossing_voxels"), static_cast<double>(Axis.FinalMeanCrossingVoxels));
    Writer.WriteValue(TEXT("core_min_crossing_voxels"), static_cast<double>(Axis.CoreMinCrossingVoxels));
    Writer.WriteValue(TEXT("core_max_crossing_voxels"), static_cast<double>(Axis.CoreMaxCrossingVoxels));
    Writer.WriteValue(TEXT("final_min_crossing_voxels"), static_cast<double>(Axis.FinalMinCrossingVoxels));
    Writer.WriteValue(TEXT("final_max_crossing_voxels"), static_cast<double>(Axis.FinalMaxCrossingVoxels));
    Writer.WriteValue(TEXT("core_periodic_amplitude_voxels"), static_cast<double>(Axis.CorePeriodicAmplitudeVoxels));
    Writer.WriteValue(TEXT("core_periodic_amplitude_cm"), static_cast<double>(Axis.CorePeriodicAmplitudeVoxels) * 25.0);
    Writer.WriteValue(TEXT("core_periodic_period_voxels"), static_cast<double>(Axis.CorePeriodicPeriodVoxels));
    Writer.WriteValue(TEXT("core_periodic_measured_samples"), Axis.CorePeriodicMeasuredSamples);
    Writer.WriteValue(TEXT("core_periodic_measured_length_voxels"), static_cast<double>(Axis.CorePeriodicMeasuredLengthVoxels));
    Writer.WriteValue(TEXT("final_periodic_amplitude_voxels"), static_cast<double>(Axis.FinalPeriodicAmplitudeVoxels));
    Writer.WriteValue(TEXT("final_periodic_amplitude_cm"), static_cast<double>(Axis.FinalPeriodicAmplitudeVoxels) * 25.0);
    Writer.WriteValue(TEXT("final_periodic_period_voxels"), static_cast<double>(Axis.FinalPeriodicPeriodVoxels));
    Writer.WriteValue(TEXT("final_periodic_measured_samples"), Axis.FinalPeriodicMeasuredSamples);
    Writer.WriteValue(TEXT("final_periodic_measured_length_voxels"), static_cast<double>(Axis.FinalPeriodicMeasuredLengthVoxels));
    Writer.WriteObjectEnd();
}

void WriteTunnelMouthProbeAxis(
    FExploreJsonWriter& Writer,
    const FExploreTunnelMouthProbeAxis& Axis,
    const TCHAR* Key)
{
    Writer.WriteObjectStart(Key);
    Writer.WriteValue(TEXT("valid_crossings"), Axis.ValidCrossings);
    Writer.WriteValue(TEXT("mean_crossing_voxels"), static_cast<double>(Axis.MeanCrossingVoxels));
    Writer.WriteValue(TEXT("min_crossing_voxels"), static_cast<double>(Axis.MinCrossingVoxels));
    Writer.WriteValue(TEXT("max_crossing_voxels"), static_cast<double>(Axis.MaxCrossingVoxels));
    Writer.WriteValue(TEXT("periodic_amplitude_voxels"), static_cast<double>(Axis.PeriodicAmplitudeVoxels));
    Writer.WriteValue(TEXT("periodic_amplitude_cm"), static_cast<double>(Axis.PeriodicAmplitudeVoxels) * 25.0);
    Writer.WriteValue(TEXT("periodic_period_voxels"), static_cast<double>(Axis.PeriodicPeriodVoxels));
    Writer.WriteValue(TEXT("periodic_measured_samples"), Axis.PeriodicMeasuredSamples);
    Writer.WriteValue(TEXT("periodic_measured_length_voxels"), static_cast<double>(Axis.PeriodicMeasuredLengthVoxels));
    Writer.WriteValue(TEXT("local_median_periodic_amplitude_voxels"), static_cast<double>(Axis.LocalMedianPeriodicAmplitudeVoxels));
    Writer.WriteValue(TEXT("local_median_periodic_amplitude_cm"), static_cast<double>(Axis.LocalMedianPeriodicAmplitudeVoxels) * 25.0);
    Writer.WriteValue(TEXT("local_median_periodic_period_voxels"), static_cast<double>(Axis.LocalMedianPeriodicPeriodVoxels));
    Writer.WriteObjectEnd();
}

void WritePlayerDimensions(FExploreJsonWriter& Writer, const TCHAR* Key)
{
    Writer.WriteObjectStart(Key);
    Writer.WriteValue(TEXT("capsule_radius_m"), static_cast<double>(FVoxelPlayerCapsuleConstants::RadiusCentimeters) / 100.0);
    Writer.WriteValue(TEXT("capsule_width_m"), static_cast<double>(2.0f * FVoxelPlayerCapsuleConstants::RadiusCentimeters) / 100.0);
    Writer.WriteValue(TEXT("capsule_half_height_m"), static_cast<double>(FVoxelPlayerCapsuleConstants::HalfHeightCentimeters) / 100.0);
    Writer.WriteValue(TEXT("capsule_height_m"), static_cast<double>(2.0f * FVoxelPlayerCapsuleConstants::HalfHeightCentimeters) / 100.0);
    Writer.WriteValue(TEXT("max_step_height_m"), static_cast<double>(FVoxelPlayerCapsuleConstants::MaxStepHeightMeters));
    Writer.WriteValue(TEXT("climbing_enabled"), true);
    Writer.WriteValue(TEXT("max_climb_height_m"), 3.0);
    Writer.WriteValue(TEXT("walkable_floor_angle_degrees"), static_cast<double>(FVoxelPlayerCapsuleConstants::WalkableFloorAngleDegrees));
    Writer.WriteObjectEnd();
}

FString BuildExploreJson(
    const FExploreArguments& Arguments,
    const FExploreWorld& World,
    const FExploreRunOutput& Output,
    bool bDeterminismAssertion,
    uint32 PayloadCrc32)
{
    FString Json;
    TSharedRef<FExploreJsonWriter> Writer =
    TJsonWriterFactory<TCHAR, TCondensedJsonPrintPolicy<TCHAR>>::Create(&Json);
    Writer->WriteObjectStart();
    Writer->WriteValue(TEXT("schema_version"), 7);
    Writer->WriteValue(TEXT("tool"), TEXT("VoxelForgeExplore"));
    Writer->WriteValue(TEXT("read_only_generation"), true);

    Writer->WriteObjectStart(TEXT("input"));
    Writer->WriteValue(TEXT("seed"), Arguments.Seed);
    Writer->WriteValue(TEXT("archetype"), ArchetypeName(Arguments.Archetype));
    Writer->WriteValue(TEXT("slot"), Arguments.Slot);
    Writer->WriteValue(TEXT("worms_enabled_override"), Arguments.bWormsEnabledOverride);
    if (Arguments.bWormsEnabledOverride)
    {
        Writer->WriteValue(TEXT("worms_enabled"), Arguments.bWormsEnabled);
    }
    Writer->WriteValue(TEXT("worm_strength_override"), Arguments.bWormStrengthOverride);
    if (Arguments.bWormStrengthOverride)
    {
        Writer->WriteValue(TEXT("worm_strength"), static_cast<double>(Arguments.WormStrength));
    }
    Writer->WriteValue(TEXT("tunnel_ablation_mask"),
        static_cast<int64>(VoxelDensityAblation::GetResolvedMask()));
    WriteTunnelFloorOverrides(*Writer, Arguments);
    Writer->WriteValue(TEXT("room_mouth_rise_override"), Arguments.bRoomMouthRiseOverride);
    if (Arguments.bRoomMouthRiseOverride)
    {
        Writer->WriteValue(TEXT("room_mouth_rise_strength"),
            static_cast<double>(Arguments.RoomMouthRise));
    }
    Writer->WriteValue(TEXT("room_mouth_rise_blend_override"),
        Arguments.bRoomMouthRiseBlendOverride);
    if (Arguments.bRoomMouthRiseBlendOverride)
    {
        Writer->WriteValue(TEXT("room_mouth_rise_blend_voxels"),
            static_cast<double>(Arguments.RoomMouthRiseBlend));
    }
    Writer->WriteValue(TEXT("surface_roughness_override"), Arguments.bSurfaceRoughnessOverride);
    if (Arguments.bSurfaceRoughnessOverride)
    {
        Writer->WriteValue(TEXT("surface_roughness"),
            static_cast<double>(Arguments.SurfaceRoughness));
    }
    Writer->WriteValue(TEXT("roughness_noise_type_override"),
        Arguments.bRoughnessNoiseTypeOverride);
    if (Arguments.bRoughnessNoiseTypeOverride)
    {
        Writer->WriteValue(TEXT("roughness_noise_type"),
            NoiseTypeName(Arguments.RoughnessNoiseType));
    }
    Writer->WriteValue(TEXT("roughness_frequency_override"),
        Arguments.bRoughnessFrequencyOverride);
    if (Arguments.bRoughnessFrequencyOverride)
    {
        Writer->WriteValue(TEXT("roughness_frequency"),
            static_cast<double>(Arguments.RoughnessFrequency));
    }
    Writer->WriteArrayStart(TEXT("modes"));
    if (Arguments.bRender) Writer->WriteValue(TEXT("render"));
    if (Arguments.bWalk) Writer->WriteValue(TEXT("walk"));
    if (Arguments.bExport) Writer->WriteValue(TEXT("export"));
    if (Arguments.bOpBounds) Writer->WriteValue(TEXT("opbounds"));
    if (Arguments.bTunnelCoreProbe) Writer->WriteValue(TEXT("tunnelcoreprobe"));
    Writer->WriteArrayEnd();
    Writer->WriteValue(TEXT("failure_focus_render"), Arguments.bFailureFocusRender);
    Writer->WriteValue(TEXT("render_step_voxels"), static_cast<double>(Arguments.RenderStepVoxels));
    Writer->WriteValue(TEXT("export_size"), Arguments.ExportSize);
    Writer->WriteValue(TEXT("export_step"), Arguments.ExportStep);
    Writer->WriteValue(TEXT("density_grid_reuse"), Arguments.bReuseDensityGrid);
    Writer->WriteValue(TEXT("block_early_out"), Arguments.bBlockEarlyOut);
    Writer->WriteValue(TEXT("game_runtime_config"), Arguments.bGameRuntimeConfig);
    Writer->WriteValue(TEXT("mesh_min_batch_size"), Arguments.MeshMinBatchSize);
    Writer->WriteValue(TEXT("profile_density"), Arguments.bProfileDensity);
    Writer->WriteValue(TEXT("profile_density_full"), Arguments.bProfileDensityFull);
    Writer->WriteValue(TEXT("perf_attribution"), Arguments.bPerfAttribution);
    Writer->WriteValue(TEXT("sample_stacks"), Arguments.bSampleStacks);
    Writer->WriteValue(TEXT("sample_stacks_interval_us"),
        static_cast<double>(Arguments.SampleStacksIntervalUs));
    Writer->WriteValue(TEXT("profile_lod"), Arguments.bProfileLod);
    Writer->WriteValue(TEXT("density_slice_requested"), Arguments.bDensitySlice);
    Writer->WriteValue(TEXT("tunnel_core_probe_requested"), Arguments.bTunnelCoreProbe);
    Writer->WriteValue(TEXT("render_target_override"), Arguments.bRenderTargetOverride);
    if (Arguments.bRenderTargetOverride)
    {
        WriteJsonVector(*Writer, TEXT("render_target_voxels"), Arguments.RenderTarget, 1.0f);
    }
    Writer->WriteValue(TEXT("op_bounds"), Arguments.bOpBounds);
    Writer->WriteValue(TEXT("budget_minutes"), static_cast<double>(Arguments.BudgetMinutes));
    Writer->WriteValue(TEXT("out_directory"), Arguments.OutDirectory);
    Writer->WriteValue(TEXT("canonical_invocation"), FString::Printf(
        TEXT("UnrealEditor-Cmd VoxelM.uproject -run=VoxelForgeExplore -seed=%d -archetype=%s "
             "-slot=%d -modes=%s -blockearlyout=%d "
             "-out=<ABSOLUTE_PLUGIN_SAVED_PATH>"),
        Arguments.Seed,
        ArchetypeName(Arguments.Archetype),
        Arguments.Slot,
        *Arguments.CanonicalModes(),
        Arguments.bBlockEarlyOut ? 1 : 0));
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("density_slice"));
    Writer->WriteValue(TEXT("status"), Output.DensitySlice.Status);
    Writer->WriteValue(TEXT("file"), Output.DensitySlice.FileName);
    Writer->WriteValue(TEXT("refusal_or_error"), Output.DensitySlice.RefusalReason);
    Writer->WriteValue(TEXT("sample_count"), Output.DensitySlice.SampleCount);
    Writer->WriteValue(TEXT("finite_sample_count"), Output.DensitySlice.FiniteSampleCount);
    Writer->WriteValue(TEXT("non_finite_sample_count"), Output.DensitySlice.NonFiniteSampleCount);
    Writer->WriteValue(TEXT("zero_crossing_count"), Output.DensitySlice.ZeroCrossingCount);
    Writer->WriteValue(TEXT("saturated_sample_count"), Output.DensitySlice.SaturatedSampleCount);
    Writer->WriteValue(TEXT("min_density"), static_cast<double>(Output.DensitySlice.MinDensity));
    Writer->WriteValue(TEXT("max_density"), static_cast<double>(Output.DensitySlice.MaxDensity));
    Writer->WriteValue(TEXT("max_abs_density"), static_cast<double>(Output.DensitySlice.MaxAbsDensity));
    Writer->WriteValue(TEXT("seconds"), Output.DensitySlice.Seconds);
    if (Arguments.bDensitySlice)
    {
        WriteJsonVector(*Writer, TEXT("origin_voxels"), Arguments.DensitySliceOrigin, 1.0f);
        WriteJsonVector(*Writer, TEXT("direction"), Arguments.DensitySliceDirection, 1.0f);
        Writer->WriteValue(TEXT("step_voxels"), static_cast<double>(Arguments.DensitySliceStep));
    }
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("tunnel_core_probe"));
    Writer->WriteValue(TEXT("status"), Output.TunnelCoreProbe.Status);
    Writer->WriteValue(TEXT("file"), Output.TunnelCoreProbe.FileName);
    Writer->WriteValue(TEXT("refusal_or_error"), Output.TunnelCoreProbe.RefusalReason);
    Writer->WriteValue(TEXT("tunnel_index"), Output.TunnelCoreProbe.TunnelIndex);
    Writer->WriteValue(TEXT("sample_count"), Output.TunnelCoreProbe.SampleCount);
    Writer->WriteValue(TEXT("step_voxels"), static_cast<double>(Output.TunnelCoreProbe.StepVoxels));
    Writer->WriteValue(TEXT("length_voxels"), static_cast<double>(Output.TunnelCoreProbe.LengthVoxels));
    WriteJsonVector(*Writer, TEXT("axis_start_voxels"), Output.TunnelCoreProbe.AxisStart, 1.0f);
    WriteJsonVector(*Writer, TEXT("axis_end_voxels"), Output.TunnelCoreProbe.AxisEnd, 1.0f);
    WriteJsonVector(*Writer, TEXT("axis_direction"), Output.TunnelCoreProbe.AxisDirection, 1.0f);
    WriteJsonVector(*Writer, TEXT("wall_direction"), Output.TunnelCoreProbe.WallDirection, 1.0f);
    Writer->WriteValue(TEXT("core_center_finite_sample_count"), Output.TunnelCoreProbe.CoreCenterFiniteSampleCount);
    Writer->WriteValue(TEXT("core_center_zero_crossing_count"), Output.TunnelCoreProbe.CoreCenterZeroCrossingCount);
    Writer->WriteValue(TEXT("final_center_finite_sample_count"), Output.TunnelCoreProbe.FinalCenterFiniteSampleCount);
    Writer->WriteValue(TEXT("final_center_zero_crossing_count"), Output.TunnelCoreProbe.FinalCenterZeroCrossingCount);
    Writer->WriteValue(TEXT("final_center_saturated_sample_count"), Output.TunnelCoreProbe.FinalCenterSaturatedSampleCount);
    Writer->WriteValue(TEXT("core_center_min"), static_cast<double>(Output.TunnelCoreProbe.CoreCenterMin));
    Writer->WriteValue(TEXT("core_center_max"), static_cast<double>(Output.TunnelCoreProbe.CoreCenterMax));
    Writer->WriteValue(TEXT("final_center_min"), static_cast<double>(Output.TunnelCoreProbe.FinalCenterMin));
    Writer->WriteValue(TEXT("final_center_max"), static_cast<double>(Output.TunnelCoreProbe.FinalCenterMax));
    Writer->WriteValue(TEXT("final_center_max_abs"), static_cast<double>(Output.TunnelCoreProbe.FinalCenterMaxAbs));
    Writer->WriteValue(TEXT("periodic_method"), TEXT("Tunnel-core axes: 32-voxel local-median detrend. Mouth axes: degree-six slow-trend detrend over the longest contiguous >=40-voxel run, with the legacy local-median value retained per axis; both use a single-sided DFT peak in the <=16-voxel band and report sinusoid amplitudes."));
    WriteTunnelCoreProbeAxis(*Writer, Output.TunnelCoreProbe.Floor, TEXT("floor"));
    WriteTunnelCoreProbeAxis(*Writer, Output.TunnelCoreProbe.Wall, TEXT("wall"));
    WriteTunnelCoreProbeAxis(*Writer, Output.TunnelCoreProbe.Ceiling, TEXT("ceiling"));
    Writer->WriteObjectStart(TEXT("mouth_probe"));
    Writer->WriteValue(TEXT("status"), Output.TunnelCoreProbe.Mouth.Status);
    Writer->WriteValue(TEXT("file"), Output.TunnelCoreProbe.Mouth.FileName);
    Writer->WriteValue(TEXT("refusal_or_error"), Output.TunnelCoreProbe.Mouth.RefusalReason);
    Writer->WriteValue(TEXT("endpoint_count"), Output.TunnelCoreProbe.Mouth.EndpointCount);
    Writer->WriteValue(TEXT("lateral_sample_count"), Output.TunnelCoreProbe.Mouth.LateralSampleCount);
    Writer->WriteValue(TEXT("lateral_step_voxels"), static_cast<double>(Output.TunnelCoreProbe.Mouth.LateralStepVoxels));
    Writer->WriteValue(TEXT("lateral_window_voxels"), static_cast<double>(Output.TunnelCoreProbe.Mouth.LateralWindowVoxels));
    Writer->WriteValue(TEXT("room_sample_step_voxels"), Output.TunnelCoreProbe.Mouth.RoomSampleStepVoxels);
    Writer->WriteValue(TEXT("room_volume_sample_count"), Output.TunnelCoreProbe.Mouth.RoomVolumeSampleCount);
    Writer->WriteValue(TEXT("room_air_sample_count"), Output.TunnelCoreProbe.Mouth.RoomAirSampleCount);
    Writer->WriteValue(TEXT("core_bottom_sample_count"), Output.TunnelCoreProbe.Mouth.CoreBottomSampleCount);
    Writer->WriteValue(TEXT("final_solid_sample_count"), Output.TunnelCoreProbe.Mouth.FinalSolidSampleCount);
    Writer->WriteValue(TEXT("core_induced_solid_sample_count"), Output.TunnelCoreProbe.Mouth.CoreInducedSolidSampleCount);
    Writer->WriteValue(TEXT("max_wall_periodic_amplitude_voxels"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxWallPeriodicAmplitudeVoxels));
    Writer->WriteValue(TEXT("max_wall_periodic_amplitude_cm"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxWallPeriodicAmplitudeVoxels) * 25.0);
    Writer->WriteValue(TEXT("max_floor_periodic_amplitude_voxels"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxFloorPeriodicAmplitudeVoxels));
    Writer->WriteValue(TEXT("max_floor_periodic_amplitude_cm"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxFloorPeriodicAmplitudeVoxels) * 25.0);
    Writer->WriteValue(TEXT("max_local_median_wall_periodic_amplitude_voxels"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxLocalMedianWallPeriodicAmplitudeVoxels));
    Writer->WriteValue(TEXT("max_local_median_wall_periodic_amplitude_cm"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxLocalMedianWallPeriodicAmplitudeVoxels) * 25.0);
    Writer->WriteValue(TEXT("max_local_median_floor_periodic_amplitude_voxels"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxLocalMedianFloorPeriodicAmplitudeVoxels));
    Writer->WriteValue(TEXT("max_local_median_floor_periodic_amplitude_cm"), static_cast<double>(Output.TunnelCoreProbe.Mouth.MaxLocalMedianFloorPeriodicAmplitudeVoxels) * 25.0);
    Writer->WriteValue(TEXT("mouth_periodic_detrend"), TEXT("degree-six smooth trend over the complete longest contiguous run; legacy local-median retained for audit"));
    Writer->WriteValue(TEXT("periodic_acceptance_cm"), 2.0);
    Writer->WriteValue(TEXT("periodic_acceptance_pass"),
        Output.TunnelCoreProbe.Mouth.MaxWallPeriodicAmplitudeVoxels * 25.0f <= 2.0f
        && Output.TunnelCoreProbe.Mouth.MaxFloorPeriodicAmplitudeVoxels * 25.0f <= 2.0f);
    Writer->WriteArrayStart(TEXT("endpoints"));
    for (const FExploreTunnelMouthProbeEndpoint& Endpoint : Output.TunnelCoreProbe.Mouth.Endpoints)
    {
        Writer->WriteObjectStart();
        Writer->WriteValue(TEXT("name"), Endpoint.Name);
        Writer->WriteValue(TEXT("room_hash"), static_cast<int64>(Endpoint.RoomHash));
        WriteJsonVector(*Writer, TEXT("mouth_voxels"), Endpoint.Mouth, 1.0f);
        Writer->WriteValue(TEXT("radius_voxels"), static_cast<double>(Endpoint.RadiusVoxels));
        Writer->WriteValue(TEXT("tunnel_floor_z"), static_cast<double>(Endpoint.TunnelFloorZ));
        Writer->WriteValue(TEXT("room_floor_crossing_z"), static_cast<double>(Endpoint.RoomFloorCrossingZ));
        Writer->WriteValue(TEXT("floor_join_delta_voxels"), static_cast<double>(Endpoint.FloorJoinDeltaVoxels));
        WriteTunnelMouthProbeAxis(*Writer, Endpoint.Wall, TEXT("wall"));
        WriteTunnelMouthProbeAxis(*Writer, Endpoint.Floor, TEXT("floor"));
        Writer->WriteObjectEnd();
    }
    Writer->WriteArrayEnd();
    Writer->WriteValue(TEXT("seconds"), Output.TunnelCoreProbe.Mouth.Seconds);
    Writer->WriteObjectEnd();
    Writer->WriteValue(TEXT("seconds"), Output.TunnelCoreProbe.Seconds);
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("summary"));
    const double SummaryMeshSeconds = Arguments.bExport
        ? Output.Export.MeshSeconds
        : (Arguments.bRender
            ? Output.Render.MeshSeconds
            : World.ExploreMeshSeconds);
    const int32 SummaryTriangleCount = Arguments.bExport
        ? Output.Export.TriangleCount
        : World.ExploreMesh.Triangles.Num() / 3;
    const FString SummaryGeometryHash = Arguments.bExport
        ? Output.Export.GeometryHash
        : World.ExploreGeometryHash;
    const double SummaryUsPerVoxel = Arguments.ExportSize > 0
        ? SummaryMeshSeconds * 1.0e6
            / static_cast<double>(Arguments.ExportSize)
            / static_cast<double>(Arguments.ExportSize)
            / static_cast<double>(Arguments.ExportSize)
        : 0.0;
    Writer->WriteValue(TEXT("mesh_seconds"), SummaryMeshSeconds);
    Writer->WriteValue(TEXT("us_per_voxel"), SummaryUsPerVoxel);
    Writer->WriteValue(TEXT("triangle_count"), SummaryTriangleCount);
    Writer->WriteValue(TEXT("geometry_hash"), SummaryGeometryHash);
    Writer->WriteObjectStart(TEXT("mesh_wall_ledger"));
    Writer->WriteValue(TEXT("mesh_seconds"), World.ExploreMeshSeconds);
    Writer->WriteValue(TEXT("preparation_seconds"), World.ExploreMeshPreparationSeconds);
    Writer->WriteValue(TEXT("density_grid_seconds"), World.ExploreDensityGridSeconds);
    Writer->WriteValue(TEXT("pre_tile_setup_seconds"), World.ExploreMeshPreTileSetupSeconds);
    Writer->WriteValue(TEXT("tile_parallel_wall_seconds"), World.ExploreMeshTaskWallSeconds);
    Writer->WriteValue(TEXT("tile_merge_seconds"), World.ExploreMeshMergeSeconds);
    Writer->WriteValue(TEXT("accounting_remainder_seconds"),
        World.ExploreMeshAccountingRemainderSeconds);
    Writer->WriteValue(TEXT("stage_sum_seconds"),
        World.ExploreMeshPreparationSeconds
            + World.ExploreDensityGridSeconds
            + World.ExploreMeshPreTileSetupSeconds
            + World.ExploreMeshTaskWallSeconds
            + World.ExploreMeshMergeSeconds);
    Writer->WriteValue(TEXT("sum_matches_mesh"),
        FMath::Abs(World.ExploreMeshAccountingRemainderSeconds) <= 0.000001);
    Writer->WriteValue(TEXT("geometry_hash_seconds"), World.ExploreMeshHashSeconds);
    Writer->WriteValue(TEXT("note"), TEXT(
        "The stage rows are one additive wall-clock ledger. Profiler buckets below are nested worker diagnostics and are not added to this ledger."));
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("density_grid_reuse"));
    Writer->WriteValue(TEXT("enabled"), World.bExploreDensityGridReused);
    Writer->WriteValue(TEXT("total_tile_grid_samples"), World.ExploreDensityGridTotalSamples);
    Writer->WriteValue(TEXT("unique_shared_grid_samples"), World.ExploreDensityGridUniqueSamples);
    Writer->WriteValue(TEXT("duplicate_evaluations_before"), World.ExploreDensityGridDuplicateSamplesBefore);
    Writer->WriteValue(TEXT("duplicate_evaluations_after"), World.ExploreDensityGridDuplicateSamplesAfter);
    Writer->WriteValue(TEXT("precompute_seconds"), World.ExploreDensityGridSeconds);
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("mesher_tasks"));
    Writer->WriteValue(TEXT("min_batch_size"), World.ExploreMeshTaskMinBatchSize);
    Writer->WriteValue(TEXT("worker_count"), World.ExploreMeshTaskWorkerCount);
    Writer->WriteValue(TEXT("job_count"), World.ExploreMeshTaskJobCount);
    Writer->WriteValue(TEXT("job_min_seconds"), World.ExploreMeshTaskMinSeconds);
    Writer->WriteValue(TEXT("job_mean_seconds"), World.ExploreMeshTaskMeanSeconds);
    Writer->WriteValue(TEXT("job_max_seconds"), World.ExploreMeshTaskMaxSeconds);
    Writer->WriteValue(TEXT("job_sum_seconds"), World.ExploreMeshTaskSumSeconds);
    Writer->WriteValue(TEXT("parallel_wall_seconds"), World.ExploreMeshTaskWallSeconds);
    Writer->WriteValue(TEXT("estimated_launch_overhead_seconds"),
        World.ExploreMeshTaskLaunchOverheadSeconds);
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("tile_ledger"));
    Writer->WriteValue(TEXT("order"), TEXT("z_then_y_then_x"));
    Writer->WriteValue(TEXT("tile_cells"), CHUNK_SIZE);
    int32 TileLod = 0;
    for (int32 SampleStep = Arguments.ExportStep; SampleStep > 1; SampleStep >>= 1)
    {
        ++TileLod;
    }
    Writer->WriteValue(TEXT("sample_step"), Arguments.ExportStep);
    Writer->WriteValue(TEXT("lod"), TileLod);
    Writer->WriteValue(TEXT("tile_count"), World.ExploreMeshTileCount);
    Writer->WriteValue(TEXT("completed_tiles"), World.ExploreMeshTilesCompleted);
    Writer->WriteArrayStart(TEXT("tiles"));
    for (int32 TileIndex = 0; TileIndex < World.ExploreMeshTilesCompleted; ++TileIndex)
    {
        const int32 TilesPerAxis = Arguments.ExportSize / CHUNK_SIZE;
        const int32 TileX = TileIndex % TilesPerAxis;
        const int32 TileY = (TileIndex / TilesPerAxis) % TilesPerAxis;
        const int32 TileZ = TileIndex / (TilesPerAxis * TilesPerAxis);
        Writer->WriteObjectStart();
        Writer->WriteValue(TEXT("index"), TileIndex);
        Writer->WriteValue(TEXT("x"), TileX);
        Writer->WriteValue(TEXT("y"), TileY);
        Writer->WriteValue(TEXT("z"), TileZ);
        Writer->WriteValue(TEXT("absolute_tile_x"),
            World.ExploreMeshOrigin.X / CHUNK_SIZE + TileX);
        Writer->WriteValue(TEXT("absolute_tile_y"),
            World.ExploreMeshOrigin.Y / CHUNK_SIZE + TileY);
        Writer->WriteValue(TEXT("absolute_tile_z"),
            World.ExploreMeshOrigin.Z / CHUNK_SIZE + TileZ);
        Writer->WriteValue(TEXT("origin_x_voxels"),
            World.ExploreMeshOrigin.X + TileX * CHUNK_SIZE);
        Writer->WriteValue(TEXT("origin_y_voxels"),
            World.ExploreMeshOrigin.Y + TileY * CHUNK_SIZE);
        Writer->WriteValue(TEXT("origin_z_voxels"),
            World.ExploreMeshOrigin.Z + TileZ * CHUNK_SIZE);
        Writer->WriteValue(TEXT("sample_step"), Arguments.ExportStep);
        Writer->WriteValue(TEXT("lod"), TileLod);
        Writer->WriteValue(TEXT("triangle_count"), World.ExploreTileTriangleCounts[TileIndex]);
        Writer->WriteValue(TEXT("geometry_hash"), World.ExploreTileGeometryHashes[TileIndex]);
        Writer->WriteObjectEnd();
    }
    Writer->WriteArrayEnd();
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("counters"));
    for (int32 Index = 0; Index < VoxelDensityProfile::CounterCount; ++Index)
    {
        Writer->WriteValue(
            VoxelDensityProfile::CounterName(static_cast<VoxelDensityProfile::ECounter>(Index)),
            static_cast<int64>(Output.Profile.Counters[Index]));
    }
    Writer->WriteObjectEnd();
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("run"));
    Writer->WriteValue(TEXT("budget_seconds"), Output.BudgetSeconds);
    Writer->WriteValue(TEXT("elapsed_seconds"), Output.ElapsedSeconds);
    Writer->WriteValue(TEXT("truncated"), Output.bTruncated);
    Writer->WriteValue(TEXT("truncated_during"), Output.TruncatedDuring);
    Writer->WriteArrayStart(TEXT("completed_modes"));
    for (const FString& Mode : Output.CompletedModes)
    {
        Writer->WriteValue(Mode);
    }
    Writer->WriteArrayEnd();
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("shared_sampling"));
    const FVoxelStrateSampleGrid* SharedGrid = nullptr;
    if (Arguments.bWalk || Arguments.bRender)
    {
        SharedGrid = &Output.Walk.SharedSampleGrid;
    }
    Writer->WriteValue(TEXT("one_grid_per_run"), true);
    Writer->WriteValue(TEXT("player_fit_mask_shared"),
        SharedGrid != nullptr && SharedGrid->HasPlayerFitMask());
    Writer->WriteValue(TEXT("grid_cells"),
        SharedGrid != nullptr ? SharedGrid->CellCount : 0);
    Writer->WriteValue(TEXT("player_fit_cells"),
        SharedGrid != nullptr ? SharedGrid->PlayerFitCellCount : 0);
    Writer->WriteValue(TEXT("render_and_walk_share_grid"), Arguments.bRender && Arguments.bWalk);
    Writer->WriteValue(TEXT("export_uses_grid"),
        Arguments.bExport && SharedGrid != nullptr && SharedGrid->HasPlayerFitMask());
    Writer->WriteValue(TEXT("export_sampling_note"), TEXT(
        "When a walk or render mode is present, export receives the same captured grid hand-off "
        "and uses its camera-fit anchor for the shared canonical mesh region; export-only runs "
        "do not sample a player-fit grid because OBJ generation has no player-fit query."));
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("world"));
    Writer->WriteValue(TEXT("voxel_size_m"), 0.25);
    Writer->WriteValue(TEXT("world_radius_voxels"), 0);
    Writer->WriteValue(TEXT("lateral_regions_enabled"), false);
    Writer->WriteValue(TEXT("diff_layer_mutated"), false);
    Writer->WriteValue(TEXT("target_strate_slot"), Arguments.Slot);
    Writer->WriteValue(TEXT("target_bottom_voxel_z"), World.TargetBottomWorldZ);
    Writer->WriteValue(TEXT("target_top_voxel_z_exclusive"), World.TargetTopWorldZ);
    Writer->WriteValue(TEXT("target_bottom_m"), static_cast<double>(World.TargetBottomWorldZ) * 0.25);
    Writer->WriteValue(TEXT("target_top_m_exclusive"), static_cast<double>(World.TargetTopWorldZ) * 0.25);
    Writer->WriteValue(TEXT("target_boundary_seal_thickness_voxels"),
        static_cast<double>(World.TargetBoundarySealThickness));
    WritePlayerDimensions(*Writer, TEXT("player_dimensions"));
    Writer->WriteObjectEnd();

    if (Arguments.bRender)
    {
        Writer->WriteObjectStart(TEXT("render"));
        Writer->WriteValue(TEXT("status"), Output.Render.Status);
        Writer->WriteValue(TEXT("refusal_or_error"), Output.Render.RefusalReason);
        Writer->WriteValue(TEXT("width_px"), Output.Render.Width);
        Writer->WriteValue(TEXT("height_px"), Output.Render.Height);
        Writer->WriteValue(TEXT("max_pixels_cap"), MaxRenderPixels);
        Writer->WriteValue(TEXT("max_fixed_density_samples_cap"), MaxRenderDensitySamples);
        Writer->WriteValue(TEXT("estimated_fixed_density_samples"),
            Output.Render.EstimatedFixedDensitySamples);
        Writer->WriteValue(TEXT("fixed_step_voxels"), static_cast<double>(Output.Render.FixedStepVoxels));
        Writer->WriteValue(TEXT("fixed_step_m"), static_cast<double>(Output.Render.FixedStepMeters));
        Writer->WriteValue(TEXT("max_distance_voxels"), static_cast<double>(Output.Render.MaxDistanceVoxels));
        Writer->WriteValue(TEXT("bisection_iterations"), Output.Render.BisectionIterations);
        Writer->WriteValue(TEXT("human_marker_height_m"), 1.76);
        Writer->WriteValue(TEXT("step_rationale"), Output.Render.StepRationale);
        Writer->WriteValue(TEXT("camera_seed_policy"), Output.Render.CameraSeedPolicy);
        Writer->WriteValue(TEXT("camera_seed_count"), Output.Render.CameraSeedCount);
        Writer->WriteValue(TEXT("all_cameras_player_fit"), Output.Render.bAllCamerasPlayerFit);
        Writer->WriteValue(TEXT("requested_viewpoint_count"), Output.Render.RequestedViewpointCount);
        Writer->WriteValue(TEXT("mesh_once"), true);
        Writer->WriteValue(TEXT("mesh_complete"), Output.Render.bMeshComplete);
        Writer->WriteValue(TEXT("mesh_seconds"), Output.Render.MeshSeconds);
        Writer->WriteValue(TEXT("geometry_hash"), World.ExploreGeometryHash);
        Writer->WriteValue(TEXT("mesh_acceleration_seconds"), Output.Render.MeshAccelerationSeconds);
        Writer->WriteValue(TEXT("raster_seconds"), Output.Render.RasterSeconds);
        Writer->WriteValue(TEXT("first_view_raster_seconds"), Output.Render.FirstViewRasterSeconds);
        Writer->WriteValue(TEXT("additional_view_raster_seconds"), Output.Render.AdditionalViewRasterSeconds);
        Writer->WriteValue(TEXT("legacy_two_view_estimated_density_samples"),
            Output.Render.LegacyTwoViewEstimatedDensitySamples);
        WriteJsonIntVector(*Writer, TEXT("mesh_region_origin_voxels"), World.ExploreMeshOrigin);
        Writer->WriteValue(TEXT("mesh_region_size_voxels"), World.ExploreMeshSize);
        Writer->WriteValue(TEXT("mesh_vertex_count"), World.ExploreMesh.Vertices.Num());
        Writer->WriteValue(TEXT("mesh_triangle_count"), World.ExploreMesh.Triangles.Num() / 3);
        Writer->WriteArrayStart(TEXT("images"));
        for (const FExploreRenderFrame& Frame : Output.Render.Frames)
        {
            Writer->WriteObjectStart();
            Writer->WriteValue(TEXT("purpose"), Frame.Purpose);
            Writer->WriteValue(TEXT("camera_seed_source"), Frame.CameraSeedSource);
            Writer->WriteValue(TEXT("file"), Frame.FileName);
            WriteJsonVector(*Writer, TEXT("camera_voxels"), Frame.CameraVoxels, 1.0f);
            WriteJsonVector(*Writer, TEXT("target_voxels"), Frame.TargetVoxels, 1.0f);
            Writer->WriteValue(TEXT("hit_pixels"), Frame.HitPixels);
            Writer->WriteValue(TEXT("scale_marker_projected"), Frame.bScaleMarkerProjected);
            Writer->WriteValue(TEXT("failure_markers_projected"), Frame.bFailureMarkersProjected);
            Writer->WriteValue(TEXT("partial"), Frame.bPartial);
            Writer->WriteValue(TEXT("scale_marker_height_m"), 1.76);
            Writer->WriteObjectEnd();
        }
        Writer->WriteArrayEnd();
        Writer->WriteObjectEnd();
    }

    if (Arguments.bWalk)
    {
        const FVoxelPlayerFitWalkReport& Report = Output.Walk.Report;
        // The primary report and origin observation are views over the one captured grid. There
        // is no second origin-inclusive sampling pass in this run.
        const FVoxelPlayerFitWalkReport& OriginReport = Output.Walk.bOriginCheckAvailable
            ? Output.Walk.OriginCheckReport : Report;
        Writer->WriteObjectStart(TEXT("walk"));
        Writer->WriteValue(TEXT("status"), Output.Walk.Status);
        Writer->WriteValue(TEXT("refusal_or_error"), Output.Walk.RefusalReason);
        Writer->WriteValue(TEXT("window_policy"), Output.Walk.WindowPolicy);
        Writer->WriteValue(TEXT("agent_policy"), TEXT(
            "fixed-order depth-first walk over the exact VF player-fit graph; walk-only six-neighbour movement; climb is reported separately and never authorizes the result; stop at departure"));
        Writer->WriteValue(TEXT("player_fit_volume_scope"), TEXT(
            "bounded fitted route window; WorldRadiusVoxels=0 has no finite whole-world volume"));
        Writer->WriteValue(TEXT("max_cells_cap"), Arguments.MaxWalkCells);
        Writer->WriteValue(TEXT("working_memory_estimate_per_cell_bytes"), EstimatedWalkBytesPerCell);
        Writer->WriteValue(TEXT("estimated_working_bytes_at_cell_cap"),
            static_cast<int64>(Arguments.MaxWalkCells) * EstimatedWalkBytesPerCell);
        Writer->WriteValue(TEXT("working_memory_cap_bytes"), MaxWalkWorkingBytes);
        Writer->WriteValue(TEXT("arrival_passage_count"), Output.Walk.ArrivalPassageCount);
        Writer->WriteValue(TEXT("departure_passage_count"), Output.Walk.DeparturePassageCount);
        Writer->WriteValue(TEXT("landing_room_probe_offsets_voxels"), 2.0);
        Writer->WriteValue(TEXT("arrival_landing_room_probe_count"),
            Output.Walk.ArrivalLandingRoomProbeCount);
        Writer->WriteValue(TEXT("arrival_landing_room_player_fit_probe_count"),
            Output.Walk.ArrivalLandingRoomPlayerFitProbeCount);
        Writer->WriteValue(TEXT("arrival_landing_room_arrival_component_probe_count"),
            Output.Walk.ArrivalLandingRoomArrivalComponentProbeCount);
        Writer->WriteValue(TEXT("arrival_landing_room_in_arrival_component"),
            Output.Walk.ArrivalLandingRoomProbeCount > 0
            && Output.Walk.ArrivalLandingRoomArrivalComponentProbeCount
                == Output.Walk.ArrivalLandingRoomProbeCount);
        Writer->WriteValue(TEXT("departure_landing_room_probe_count"),
            Output.Walk.DepartureLandingRoomProbeCount);
        Writer->WriteValue(TEXT("departure_landing_room_player_fit_probe_count"),
            Output.Walk.DepartureLandingRoomPlayerFitProbeCount);
        Writer->WriteValue(TEXT("departure_landing_room_arrival_component_probe_count"),
            Output.Walk.DepartureLandingRoomArrivalComponentProbeCount);
        Writer->WriteValue(TEXT("departure_landing_room_in_arrival_component"),
            Output.Walk.DepartureLandingRoomProbeCount > 0
            && Output.Walk.DepartureLandingRoomArrivalComponentProbeCount
                == Output.Walk.DepartureLandingRoomProbeCount);
        if (Output.Walk.bHasArrival)
        {
            WriteJsonVector(*Writer, TEXT("arrival_mouth_voxels"), Output.Walk.ArrivalVoxels, 1.0f);
            WriteJsonVector(*Writer, TEXT("arrival_mouth_metres"), Output.Walk.ArrivalVoxels, 0.25f);
        }
        if (Output.Walk.bHasDeparture)
        {
            WriteJsonVector(*Writer, TEXT("departure_mouth_voxels"), Output.Walk.DepartureVoxels, 1.0f);
            WriteJsonVector(*Writer, TEXT("departure_mouth_metres"), Output.Walk.DepartureVoxels, 0.25f);
        }
        Writer->WriteValue(TEXT("connectivity_result"), ConnectivityResultName(Report.Result));
        Writer->WriteValue(TEXT("connectivity_result_code"), static_cast<int32>(Report.Result));
        Writer->WriteValue(TEXT("can_reach_departure"), Report.bCanReachDeparture);
        Writer->WriteValue(TEXT("walk_only_can_reach_departure"), Report.bWalkOnlyCanReachDeparture);
        Writer->WriteValue(TEXT("climb_can_reach_departure"), Report.bClimbCanReachDeparture);
        Writer->WriteValue(TEXT("start_snapped"), Report.bStartSnapped);
        Writer->WriteValue(TEXT("goal_snapped"), Report.bGoalSnapped);
        Writer->WriteValue(TEXT("route_retries"), Report.NumRouteRetries);
        Writer->WriteValue(TEXT("climbing_enabled"), Report.bClimbingEnabled);
        Writer->WriteValue(TEXT("max_climb_height_m"), static_cast<double>(Report.MaxClimbHeightMeters));
        Writer->WriteValue(TEXT("player_fit_volume_cells"), Report.PlayerFitVolumeCells);
        Writer->WriteValue(TEXT("reachable_player_fit_cells"), Report.ReachablePlayerFitCells);
        Writer->WriteValue(TEXT("reachable_player_fit_fraction"), static_cast<double>(Report.ReachablePlayerFitFraction));
        Writer->WriteValue(TEXT("walk_only_reachable_player_fit_cells"),
            Report.WalkOnlyReachablePlayerFitCells);
        Writer->WriteValue(TEXT("climb_reachable_player_fit_cells"),
            Report.ClimbReachablePlayerFitCells);
        Writer->WriteValue(TEXT("climb_edges"), Report.ClimbEdges);
        Writer->WriteValue(TEXT("mine_required_player_fit_cells"),
            Report.MineRequiredPlayerFitCells);
        Writer->WriteValue(TEXT("climb_reachable_player_fit_fraction"),
            static_cast<double>(Report.ClimbReachablePlayerFitFraction));
        Writer->WriteValue(TEXT("sampled_num_x"), Report.SampledNumX);
        Writer->WriteValue(TEXT("sampled_num_y"), Report.SampledNumY);
        Writer->WriteValue(TEXT("sampled_num_z"), Report.SampledNumZ);
        Writer->WriteValue(TEXT("sampled_bounds_units"), TEXT("voxels"));
        Writer->WriteValue(TEXT("sampled_min_z"), Report.SampledMinZ);
        Writer->WriteValue(TEXT("sampled_max_z_exclusive"), Report.SampledMaxZ);
        Writer->WriteValue(TEXT("sampled_min_x"), static_cast<double>(Report.SampledMinX));
        Writer->WriteValue(TEXT("sampled_max_x_exclusive"), static_cast<double>(Report.SampledMaxX));
        Writer->WriteValue(TEXT("sampled_min_y"), static_cast<double>(Report.SampledMinY));
        Writer->WriteValue(TEXT("sampled_max_y_exclusive"), static_cast<double>(Report.SampledMaxY));
        Writer->WriteValue(TEXT("agent_graph_traversals"), Report.AgentGraphTraversals);
        Writer->WriteValue(TEXT("climb_traversals"), Report.ClimbTraversals);
        Writer->WriteValue(TEXT("distance_travelled_m"), static_cast<double>(Report.DistanceTravelledMeters));
        Writer->WriteValue(TEXT("straight_line_m"), static_cast<double>(Report.StraightLineMeters));
        Writer->WriteValue(TEXT("tortuosity"), static_cast<double>(Report.Tortuosity));
        Writer->WriteValue(TEXT("dead_ends_encountered"), Report.DeadEndsEncountered);
        Writer->WriteValue(TEXT("dead_ends_per_100m"), static_cast<double>(Report.DeadEndsPer100m));
        Writer->WriteValue(TEXT("capsule_radius_m"), static_cast<double>(Report.CapsuleRadiusMeters));
        Writer->WriteValue(TEXT("capsule_width_m"), static_cast<double>(Report.CapsuleWidthMeters));
        Writer->WriteValue(TEXT("capsule_height_m"), static_cast<double>(Report.CapsuleHeightMeters));
        Writer->WriteValue(TEXT("narrow_gap_threshold_m"), static_cast<double>(Report.NarrowGapThresholdMeters));
        Writer->WriteValue(TEXT("narrow_gap_traversals"), Report.NarrowGapTraversals);
        Writer->WriteValue(TEXT("narrow_gap_fraction"), static_cast<double>(Report.NarrowGapFraction));
        Writer->WriteValue(TEXT("narrow_gap_events_per_100m"), static_cast<double>(Report.NarrowGapEventsPer100m));
        Writer->WriteValue(TEXT("narrow_gap_definition"), Report.NarrowGapDefinition);
        Writer->WriteValue(TEXT("player_fit_components"), Report.PlayerFitComponents);
        Writer->WriteValue(TEXT("largest_player_fit_component_cells"), Report.LargestPlayerFitComponentCells);
        Writer->WriteValue(TEXT("arrival_component_cells"), Report.ArrivalComponentCells);
        Writer->WriteValue(TEXT("departure_component_cells"), Report.DepartureComponentCells);
        Writer->WriteValue(TEXT("mouth_component_gap_voxels"), static_cast<double>(Report.MouthComponentGapVoxels));
        Writer->WriteValue(TEXT("mouth_component_gap_m"), static_cast<double>(Report.MouthComponentGapVoxels)
            * FVoxelPlayerCapsuleConstants::VoxelSizeMeters);
        Writer->WriteValue(TEXT("agent_final_position_available"), Report.bHasAgentFinalPosition);
        if (Report.bHasAgentFinalPosition)
        {
            WriteJsonVector(*Writer, TEXT("agent_final_position_voxels"), Report.AgentFinalVoxels, 1.0f);
            WriteJsonVector(*Writer, TEXT("agent_final_position_metres"), Report.AgentFinalVoxels, 0.25f);
        }
        Writer->WriteValue(TEXT("last_reached_position_available"), Report.bHasLastReachedPosition);
        if (Report.bHasLastReachedPosition)
        {
            WriteJsonVector(*Writer, TEXT("last_reached_position_voxels"), Report.LastReachedVoxels, 1.0f);
            WriteJsonVector(*Writer, TEXT("last_reached_position_metres"), Report.LastReachedVoxels, 0.25f);
        }
        Writer->WriteValue(TEXT("target_component_nearest_cell_available"), Report.bHasTargetComponentNearestCell);
        if (Report.bHasTargetComponentNearestCell)
        {
            WriteJsonVector(*Writer, TEXT("target_component_nearest_cell_voxels"),
                Report.TargetComponentNearestVoxels, 1.0f);
            WriteJsonVector(*Writer, TEXT("target_component_nearest_cell_metres"),
                Report.TargetComponentNearestVoxels, 0.25f);
        }
        Writer->WriteValue(TEXT("agent_to_target_component_gap_voxels"),
            static_cast<double>(Report.AgentToTargetComponentGapVoxels));
        Writer->WriteValue(TEXT("agent_to_target_component_gap_m"),
            static_cast<double>(Report.AgentToTargetComponentGapVoxels)
                * FVoxelPlayerCapsuleConstants::VoxelSizeMeters);
        Writer->WriteValue(TEXT("origin_column_measurement_window"),
            TEXT("origin-inclusive mouth-AABB + margin"));
        Writer->WriteValue(TEXT("origin_column_in_sampled_window"), OriginReport.bOriginColumnInSampledWindow);
        Writer->WriteValue(TEXT("origin_column_has_player_fit"), OriginReport.bOriginColumnHasPlayerFit);
        Writer->WriteValue(TEXT("origin_column_player_fit_cells"), OriginReport.OriginColumnPlayerFitCells);
        Writer->WriteValue(TEXT("origin_column_reachable_from_arrival"), OriginReport.bOriginColumnReachable);
        Writer->WriteValue(TEXT("reachable_set_to_origin_column_voxels"),
            static_cast<double>(OriginReport.ReachableSetToOriginColumnVoxels));
        Writer->WriteValue(TEXT("reachable_set_to_origin_column_m"),
            static_cast<double>(OriginReport.ReachableSetToOriginColumnVoxels)
                * FVoxelPlayerCapsuleConstants::VoxelSizeMeters);
        Writer->WriteObjectStart(TEXT("origin_check"));
        Writer->WriteValue(TEXT("attempted"), Output.Walk.bOriginCheckAttempted);
        Writer->WriteValue(TEXT("available"), Output.Walk.bOriginCheckAvailable);
        Writer->WriteValue(TEXT("refusal_or_error"), Output.Walk.OriginCheckRefusalReason);
        if (Output.Walk.bOriginCheckAvailable)
        {
            const FVoxelPlayerFitWalkReport& OriginCheckReport = Output.Walk.OriginCheckReport;
            Writer->WriteValue(TEXT("window_policy"), TEXT("origin-inclusive mouth-AABB + margin"));
            Writer->WriteValue(TEXT("connectivity_result"), ConnectivityResultName(OriginCheckReport.Result));
            Writer->WriteValue(TEXT("can_reach_departure"), OriginCheckReport.bCanReachDeparture);
            Writer->WriteValue(TEXT("walk_only_can_reach_departure"),
                OriginCheckReport.bWalkOnlyCanReachDeparture);
            Writer->WriteValue(TEXT("climb_can_reach_departure"),
                OriginCheckReport.bClimbCanReachDeparture);
            Writer->WriteValue(TEXT("sampled_num_x"), OriginCheckReport.SampledNumX);
            Writer->WriteValue(TEXT("sampled_num_y"), OriginCheckReport.SampledNumY);
            Writer->WriteValue(TEXT("sampled_num_z"), OriginCheckReport.SampledNumZ);
            Writer->WriteValue(TEXT("sampled_min_x"), static_cast<double>(OriginCheckReport.SampledMinX));
            Writer->WriteValue(TEXT("sampled_max_x_exclusive"), static_cast<double>(OriginCheckReport.SampledMaxX));
            Writer->WriteValue(TEXT("sampled_min_y"), static_cast<double>(OriginCheckReport.SampledMinY));
            Writer->WriteValue(TEXT("sampled_max_y_exclusive"), static_cast<double>(OriginCheckReport.SampledMaxY));
            Writer->WriteValue(TEXT("sampled_min_z"), OriginCheckReport.SampledMinZ);
            Writer->WriteValue(TEXT("sampled_max_z_exclusive"), OriginCheckReport.SampledMaxZ);
            Writer->WriteValue(TEXT("player_fit_cells"), OriginCheckReport.PlayerFitVolumeCells);
            Writer->WriteValue(TEXT("reachable_player_fit_cells"), OriginCheckReport.ReachablePlayerFitCells);
            Writer->WriteValue(TEXT("reachable_player_fit_fraction"),
                static_cast<double>(OriginCheckReport.ReachablePlayerFitFraction));
            Writer->WriteValue(TEXT("walk_only_reachable_player_fit_cells"),
                OriginCheckReport.WalkOnlyReachablePlayerFitCells);
            Writer->WriteValue(TEXT("climb_reachable_player_fit_cells"),
                OriginCheckReport.ClimbReachablePlayerFitCells);
            Writer->WriteValue(TEXT("climb_edges"), OriginCheckReport.ClimbEdges);
            Writer->WriteValue(TEXT("mine_required_player_fit_cells"),
                OriginCheckReport.MineRequiredPlayerFitCells);
            Writer->WriteValue(TEXT("climb_reachable_player_fit_fraction"),
                static_cast<double>(OriginCheckReport.ClimbReachablePlayerFitFraction));
            Writer->WriteValue(TEXT("player_fit_components"), OriginCheckReport.PlayerFitComponents);
            Writer->WriteValue(TEXT("arrival_component_cells"), OriginCheckReport.ArrivalComponentCells);
            Writer->WriteValue(TEXT("departure_component_cells"), OriginCheckReport.DepartureComponentCells);
            Writer->WriteValue(TEXT("mouth_component_gap_voxels"),
                static_cast<double>(OriginCheckReport.MouthComponentGapVoxels));
            Writer->WriteValue(TEXT("origin_column_in_sampled_window"),
                OriginCheckReport.bOriginColumnInSampledWindow);
            Writer->WriteValue(TEXT("origin_column_has_player_fit"),
                OriginCheckReport.bOriginColumnHasPlayerFit);
            Writer->WriteValue(TEXT("origin_column_player_fit_cells"),
                OriginCheckReport.OriginColumnPlayerFitCells);
            Writer->WriteValue(TEXT("origin_column_reachable_from_arrival"),
                OriginCheckReport.bOriginColumnReachable);
            Writer->WriteValue(TEXT("reachable_set_to_origin_column_voxels"),
                static_cast<double>(OriginCheckReport.ReachableSetToOriginColumnVoxels));
            Writer->WriteValue(TEXT("reachable_set_to_origin_column_m"),
                static_cast<double>(OriginCheckReport.ReachableSetToOriginColumnVoxels)
                    * FVoxelPlayerCapsuleConstants::VoxelSizeMeters);
        }
        Writer->WriteObjectEnd();
        Writer->WriteObjectEnd();
    }

    if (Arguments.bExport)
    {
        Writer->WriteObjectStart(TEXT("export"));
        Writer->WriteValue(TEXT("status"), Output.Export.Status);
        Writer->WriteValue(TEXT("refusal_or_error"), Output.Export.RefusalReason);
        Writer->WriteValue(TEXT("format"), TEXT("OBJ"));
        Writer->WriteValue(TEXT("skirts"), false);
        Writer->WriteValue(TEXT("obj_position_units"), TEXT("metres"));
        Writer->WriteValue(TEXT("obj_uv_units"), TEXT("voxels"));
        Writer->WriteValue(TEXT("why_obj"), TEXT(
            "OBJ is dependency-free, streamable, deterministic text that browser viewers can load; "
            "the mesh itself is still produced by VoxelMarchingCubesMesher."));
        Writer->WriteValue(TEXT("mesh_file"), Output.Export.MeshFileName);
        Writer->WriteValue(TEXT("manifest_file"), Output.Export.ManifestFileName);
        WriteJsonIntVector(*Writer, TEXT("region_origin_voxels"), Output.Export.RegionOrigin);
        WriteJsonBounds(*Writer, TEXT("region_bounds_voxels"), Output.Export.RegionOrigin, Output.Export.RegionSize, 0.25f);
        Writer->WriteValue(TEXT("region_size_cells_per_axis"), Output.Export.RegionSize);
        Writer->WriteValue(TEXT("canonical_mesher_tile_cells"), CHUNK_SIZE);
        Writer->WriteValue(TEXT("canonical_mesher_tile_count"), Output.Export.MesherTileCount);
        Writer->WriteValue(TEXT("estimated_working_bytes"), Output.Export.EstimatedWorkingBytes);
        Writer->WriteValue(TEXT("working_memory_cap_bytes"), Output.Export.WorkingMemoryCapBytes);
        Writer->WriteValue(TEXT("mesh_array_bytes"), Output.Export.MeshArrayBytes);
        Writer->WriteValue(TEXT("mesh_array_bytes_sum_over_tiles"), Output.Export.MeshArrayBytes);
        Writer->WriteValue(TEXT("mesh_file_size_bytes"), Output.Export.MeshFileSizeBytes);
        Writer->WriteValue(TEXT("vertex_count"), Output.Export.VertexCount);
        Writer->WriteValue(TEXT("triangle_count"), Output.Export.TriangleCount);
        WriteSurfaceReliefMetrics(*Writer, Output.Export.SurfaceMetrics);
        Writer->WriteValue(TEXT("mesh_seconds"), Output.Export.MeshSeconds);
        Writer->WriteValue(TEXT("mesh_us_per_voxel"), Output.Export.MeshUsPerVoxel);
        Writer->WriteValue(TEXT("geometry_hash_seconds"), World.ExploreMeshHashSeconds);
        Writer->WriteValue(TEXT("measure_seconds"), Output.Export.MeasureSeconds);
        Writer->WriteValue(TEXT("obj_write_seconds"), Output.Export.ObjWriteSeconds);
        Writer->WriteValue(TEXT("manifest_seconds"), Output.Export.ManifestSeconds);
        Writer->WriteValue(TEXT("export_wall_seconds"), Output.Export.ExportWallSeconds);
        Writer->WriteValue(TEXT("export_accounting_remainder_seconds"),
            Output.Export.ExportAccountingRemainderSeconds);
        Writer->WriteValue(TEXT("geometry_hash"), Output.Export.GeometryHash);
        Writer->WriteValue(TEXT("density_grid_reuse"), World.bExploreDensityGridReused);
        Writer->WriteValue(TEXT("density_grid_precompute_seconds"), World.ExploreDensityGridSeconds);
        Writer->WriteValue(TEXT("density_grid_duplicate_evaluations_before"),
            World.ExploreDensityGridDuplicateSamplesBefore);
        Writer->WriteValue(TEXT("density_grid_duplicate_evaluations_after"),
            World.ExploreDensityGridDuplicateSamplesAfter);
        Writer->WriteValue(TEXT("mesh_task_min_batch_size"), World.ExploreMeshTaskMinBatchSize);
        Writer->WriteValue(TEXT("mesh_task_worker_count"), World.ExploreMeshTaskWorkerCount);
        Writer->WriteValue(TEXT("mesh_task_job_count"), World.ExploreMeshTaskJobCount);
        Writer->WriteValue(TEXT("mesh_task_job_mean_seconds"), World.ExploreMeshTaskMeanSeconds);
        Writer->WriteValue(TEXT("mesh_task_job_max_seconds"), World.ExploreMeshTaskMaxSeconds);
        Writer->WriteValue(TEXT("mesh_task_parallel_wall_seconds"), World.ExploreMeshTaskWallSeconds);
        Writer->WriteValue(TEXT("mesh_task_launch_overhead_seconds"),
            World.ExploreMeshTaskLaunchOverheadSeconds);
        Writer->WriteValue(TEXT("export_step"), Arguments.ExportStep);
        Writer->WriteValue(TEXT("truncated"), Output.Export.bTruncated);
        Writer->WriteValue(TEXT("canonical_mesher_tiles_completed"), Output.Export.MesherTilesCompleted);
        Writer->WriteObjectEnd();
    }

    Writer->WriteObjectStart(TEXT("profiler"));
    Writer->WriteValue(TEXT("mode"),
        Output.bHasProfile && Output.Profile.Mode != VoxelDensityProfile::EMode::Disabled
            ? (Output.Profile.Mode == VoxelDensityProfile::EMode::Full
                ? TEXT("full")
                : (Output.Profile.Mode == VoxelDensityProfile::EMode::Attribution
                    ? TEXT("attribution") : TEXT("sampled")))
            : TEXT("disabled"));
    Writer->WriteValue(TEXT("sample_interval"), static_cast<int32>(Output.Profile.SampleInterval));
    Writer->WriteValue(TEXT("timer_pair_cycles"), static_cast<int64>(Output.Profile.TimerPairCycles));
    Writer->WriteValue(TEXT("timer_pair_microseconds"),
        static_cast<double>(Output.Profile.TimerPairCycles)
            * FPlatformTime::GetSecondsPerCycle64() * 1.0e6);
    Writer->WriteValue(TEXT("timing_is_report_only"), true);
    Writer->WriteValue(TEXT("generation_can_depend_on_profiler"), false);
    Writer->WriteValue(TEXT("fine_scope_timing"),
        Output.Profile.Mode == VoxelDensityProfile::EMode::Full);
    Writer->WriteValue(TEXT("attribution_scope_timing"),
        Output.Profile.Mode == VoxelDensityProfile::EMode::Attribution);
    Writer->WriteValue(TEXT("sampled_scope_policy"), TEXT(
        "Attribution mode keeps the parent and additive mesh ledger wall clocks, samples hot "
        "component scopes, and records classifier detail; full mode remains the invasive per-scope "
        "diagnostic."));
    Writer->WriteObjectStart(TEXT("wall_clock_self_check"));
    Writer->WriteValue(TEXT("scope"), Output.ProfilerComparison.Scope);
    Writer->WriteValue(TEXT("profiled_total_seconds"), Output.ProfilerComparison.ProfiledSeconds);
    Writer->WriteValue(TEXT("unprofiled_total_seconds"), Output.ProfilerComparison.UnprofiledSeconds);
    Writer->WriteValue(TEXT("discrepancy_seconds"), Output.ProfilerComparison.DiscrepancySeconds);
    Writer->WriteValue(TEXT("discrepancy_percent"), Output.ProfilerComparison.DiscrepancyPercent);
    Writer->WriteValue(TEXT("profiled_over_unprofiled_ratio"), Output.ProfilerComparison.Ratio);
    Writer->WriteValue(TEXT("profiled_geometry_hash"), Output.ProfilerComparison.ProfiledGeometryHash);
    Writer->WriteValue(TEXT("unprofiled_geometry_hash"), Output.ProfilerComparison.UnprofiledGeometryHash);
    Writer->WriteValue(TEXT("geometry_equal"), Output.ProfilerComparison.bGeometryEqual);
    Writer->WriteValue(TEXT("self_check"), Output.ProfilerComparison.SelfCheck);
    Writer->WriteObjectEnd();
    const double CycleToMicroseconds = FPlatformTime::GetSecondsPerCycle64() * 1.0e6;
    Writer->WriteObjectStart(TEXT("counters"));
    for (int32 Index = 0; Index < VoxelDensityProfile::CounterCount; ++Index)
    {
        Writer->WriteValue(
            VoxelDensityProfile::CounterName(static_cast<VoxelDensityProfile::ECounter>(Index)),
            static_cast<int64>(Output.Profile.Counters[Index]));
    }
    Writer->WriteObjectEnd();
    const VoxelDensityProfile::FSnapshot::FClassifierStats& Classifier = Output.Profile.Classifier;
    Writer->WriteObjectStart(TEXT("classifier"));
    Writer->WriteValue(TEXT("calls"), static_cast<int64>(Classifier.Calls));
    Writer->WriteValue(TEXT("sampled_calls"), static_cast<int64>(Classifier.SampledCalls));
    Writer->WriteValue(TEXT("sample_fraction"), Classifier.Calls > 0
        ? static_cast<double>(Classifier.SampledCalls) / static_cast<double>(Classifier.Calls)
        : 0.0);
    Writer->WriteValue(TEXT("refine_nodes"), static_cast<int64>(Classifier.RefineNodes));
    Writer->WriteValue(TEXT("interval_stack_box_calls"), static_cast<int64>(Classifier.StackBoxCalls));
    Writer->WriteValue(TEXT("whole_mixed_nodes"), static_cast<int64>(Classifier.WholeMixedNodes));
    Writer->WriteValue(TEXT("whole_solid_nodes"), static_cast<int64>(Classifier.WholeSolidNodes));
    Writer->WriteValue(TEXT("whole_air_nodes"), static_cast<int64>(Classifier.WholeAirNodes));
    Writer->WriteValue(TEXT("needs_final_field_nodes"), static_cast<int64>(Classifier.NeedsFinalFieldNodes));
    Writer->WriteValue(TEXT("split_nodes"), static_cast<int64>(Classifier.SplitNodes));
    Writer->WriteValue(TEXT("max_refinement_depth"), static_cast<int64>(Classifier.MaxRefinementDepth));
    Writer->WriteValue(TEXT("exact_core_samples"), static_cast<int64>(Classifier.ExactCoreSamples));
    Writer->WriteValue(TEXT("exact_final_samples"), static_cast<int64>(Classifier.ExactFinalSamples));
    Writer->WriteValue(TEXT("exact_core_cache_hits"), static_cast<int64>(Classifier.ExactCoreCacheHits));
    Writer->WriteValue(TEXT("exact_final_cache_hits"), static_cast<int64>(Classifier.ExactFinalCacheHits));
    Writer->WriteValue(TEXT("exact_core_leaves"), static_cast<int64>(Classifier.ExactCoreLeaves));
    Writer->WriteValue(TEXT("exact_final_leaves"), static_cast<int64>(Classifier.ExactFinalLeaves));
    Writer->WriteValue(TEXT("interval_stack_box_us"), static_cast<double>(Classifier.StackBoxCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("exact_core_us"), static_cast<double>(Classifier.ExactCoreCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("exact_final_us"), static_cast<double>(Classifier.ExactFinalCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("room_tail_queries"), static_cast<int64>(Classifier.RoomTailQueries));
    Writer->WriteValue(TEXT("room_tail_evaluated"), static_cast<int64>(Classifier.RoomTailEvaluated));
    Writer->WriteValue(TEXT("room_tail_us"), static_cast<double>(Classifier.RoomTailCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("room_propagate_us"), static_cast<double>(Classifier.RoomPropagateCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("room_exact_primitive_us"), static_cast<double>(Classifier.RoomExactPrimitiveCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("room_cache_window_us"), static_cast<double>(Classifier.RoomCacheWindowCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("room_count"), static_cast<int64>(Classifier.RoomNumRooms));
    Writer->WriteValue(TEXT("tunnel_count"), static_cast<int64>(Classifier.RoomNumTunnels));
    Writer->WriteValue(TEXT("room_floor_join_count"), static_cast<int64>(Classifier.RoomNumRoomFloorJoins));
    Writer->WriteValue(TEXT("pit_count"), static_cast<int64>(Classifier.RoomNumPits));
    Writer->WriteValue(TEXT("chimney_count"), static_cast<int64>(Classifier.RoomNumChimneys));
    Writer->WriteObjectEnd();
    auto WriteCacheBreakdown = [&Writer](
        const TCHAR* Name,
        const VoxelDensityProfile::FCacheMemoryBreakdown& Breakdown)
    {
        Writer->WriteObjectStart(Name);
        Writer->WriteValue(TEXT("slot_storage_bytes"), static_cast<int64>(Breakdown.SlotStorageBytes));
        Writer->WriteValue(TEXT("op_stack_bytes"), static_cast<int64>(Breakdown.OpStackBytes));
        Writer->WriteValue(TEXT("rooms_bytes"), static_cast<int64>(Breakdown.RoomsBytes));
        Writer->WriteValue(TEXT("room_floor_joins_bytes"), static_cast<int64>(Breakdown.RoomFloorJoinsBytes));
        Writer->WriteValue(TEXT("tunnels_bytes_including_control_points"), static_cast<int64>(Breakdown.TunnelsBytes));
        Writer->WriteValue(TEXT("pits_bytes"), static_cast<int64>(Breakdown.PitsBytes));
        Writer->WriteValue(TEXT("chimneys_bytes"), static_cast<int64>(Breakdown.ChimneysBytes));
        Writer->WriteValue(TEXT("columns_bytes"), static_cast<int64>(Breakdown.ColumnsBytes));
        Writer->WriteValue(TEXT("support_column_entries_bytes"), static_cast<int64>(Breakdown.SupportColumnEntriesBytes));
        Writer->WriteValue(TEXT("support_columns_bytes"), static_cast<int64>(Breakdown.SupportColumnsBytes));
        Writer->WriteValue(TEXT("support_column_intervals_bytes"), static_cast<int64>(Breakdown.SupportColumnIntervalsBytes));
        Writer->WriteValue(TEXT("dynamic_bytes"), static_cast<int64>(Breakdown.DynamicBytes()));
        Writer->WriteValue(TEXT("total_bytes"), static_cast<int64>(Breakdown.TotalBytes()));
        Writer->WriteObjectEnd();
    };
    Writer->WriteObjectStart(TEXT("cache_memory"));
    WriteCacheBreakdown(TEXT("tunnel_network"), Output.Profile.TunnelCacheBreakdown);
    WriteCacheBreakdown(TEXT("room_graph"), Output.Profile.RoomGraphCacheBreakdown);
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("buckets"));
    for (int32 Index = 0; Index < VoxelDensityProfile::BucketCount; ++Index)
    {
        Writer->WriteObjectStart(VoxelDensityProfile::BucketName(
            static_cast<VoxelDensityProfile::EBucket>(Index)));
        Writer->WriteValue(TEXT("calls"), static_cast<int64>(Output.Profile.Calls[Index]));
        Writer->WriteValue(TEXT("samples"), static_cast<int64>(Output.Profile.Samples[Index]));
        Writer->WriteValue(TEXT("worker_count"), static_cast<int32>(Output.Profile.ActiveWorkers[Index]));
        Writer->WriteValue(TEXT("cpu_us"),
            static_cast<double>(Output.Profile.Cycles[Index]) * CycleToMicroseconds);
        Writer->WriteValue(TEXT("wall_us"),
            static_cast<double>(Output.Profile.WallCycles[Index]) * CycleToMicroseconds);
        Writer->WriteValue(TEXT("total_us"),
            static_cast<double>(Output.Profile.WallCycles[Index]) * CycleToMicroseconds);
        Writer->WriteObjectEnd();
    }
    Writer->WriteObjectEnd();
    const VoxelDensityProfile::EBucket DensityPhases[] = {
        VoxelDensityProfile::EBucket::DensityPrologue,
        VoxelDensityProfile::EBucket::DensityCore,
        VoxelDensityProfile::EBucket::DensityDisturbances,
        VoxelDensityProfile::EBucket::DensityStructuralPosts,
        VoxelDensityProfile::EBucket::DensityBoundarySeal,
        VoxelDensityProfile::EBucket::DensityDiffLayer,
        VoxelDensityProfile::EBucket::DensityTail,
    };
    uint64 DensityPhaseCycles = 0;
    for (const VoxelDensityProfile::EBucket Phase : DensityPhases)
    {
        DensityPhaseCycles += Output.Profile.WallCycles[static_cast<int32>(Phase)];
    }
    const uint64 DensityParentCycles = Output.Profile.WallCycles[
        static_cast<int32>(VoxelDensityProfile::EBucket::GetDensityAt)];
    const int64 DensityRawGap = static_cast<int64>(DensityParentCycles)
        - static_cast<int64>(DensityPhaseCycles);
    Writer->WriteObjectStart(TEXT("density_ledger"));
    Writer->WriteValue(TEXT("parent_us"), static_cast<double>(DensityParentCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("raw_phase_sum_us"), static_cast<double>(DensityPhaseCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("unattributed_us"), static_cast<double>(DensityRawGap) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("ledger_sum_us"), static_cast<double>(DensityParentCycles) * CycleToMicroseconds);
    Writer->WriteValue(TEXT("raw_phase_sum_matches_parent"),
        FMath::Abs(static_cast<double>(DensityRawGap) * CycleToMicroseconds) <= 1.0);
    Writer->WriteValue(TEXT("ledger_sum_matches_parent"), true);
    Writer->WriteValue(TEXT("sum_matches_parent"), true);
    Writer->WriteValue(TEXT("fine_buckets_enabled"),
        Output.Profile.Mode == VoxelDensityProfile::EMode::Full);
    Writer->WriteValue(TEXT("note"), Output.Profile.Mode == VoxelDensityProfile::EMode::Full
        ? TEXT("Phase buckets are the non-overlapping ledger. Named operation buckets are nested diagnostics and must not be added to the phase ledger.")
        : (Output.Profile.Mode == VoxelDensityProfile::EMode::Attribution
            ? TEXT("Attribution mode samples component scopes and keeps the separate export wall-clock ledger additive; nested worker buckets must not be added to that ledger.")
            : TEXT("Sampled mode intentionally disables fine phase and operation timers so the parent survives contact with reality; use -profiledensityfull or attribution mode for component timing.")));
    Writer->WriteObjectEnd();
    Writer->WriteObjectEnd();

    Writer->WriteObjectStart(TEXT("determinism"));
    Writer->WriteValue(TEXT("same_arguments_byte_identical_contract"), true);
    Writer->WriteValue(TEXT("canonical_repeat_equal"), bDeterminismAssertion);
    Writer->WriteValue(TEXT("assertion"), bDeterminismAssertion ? TEXT("passed") : TEXT("failed"));
    Writer->WriteValue(TEXT("canonical_payload_crc32"), FString::Printf(TEXT("%08X"), PayloadCrc32));
    Writer->WriteObjectEnd();
    Writer->WriteObjectEnd();
    return Writer->Close() ? Json : FString();
}

// Density-bound APIs use FLT_MAX as the documented "unknown/unbounded" sentinel.  It is finite
// according to IEEE-754, so FMath::IsFinite alone would misreport the very failure this audit is
// intended to expose as a real numeric envelope.
bool ExploreIsKnownDensityBound(float Value)
{
    return FMath::IsFinite(Value) && Value >= 0.0f && Value < FLT_MAX;
}

struct FExploreOpBoundsAggregate
{
    FString Name;
    uint64 Blocks = 0;
    uint64 Samples = 0;
    uint64 ForcedBoxes = 0;
    uint64 ForcedSolidBoxes = 0;
    uint64 ForcedAirBoxes = 0;
    float MaxForcedMargin = 0.0f;
    uint64 EffectCounts[4]{};
    bool bCarveBoundKnown = true;
    bool bFillBoundKnown = true;
    float MaxCarveSupremum = 0.0f;
    float MaxFillSupremum = 0.0f;
    uint64 UnknownCarveBoundBoxes = 0;
    uint64 UnknownFillBoundBoxes = 0;
    bool bHasDensityActual = false;
    float ActualDensityDeltaMin = FLT_MAX;
    float ActualDensityDeltaMax = -FLT_MAX;
    double MaxDirectionalRatio = 0.0;
    double MaxConservativeRatio = 0.0;
    bool bRatioFinite = true;
    uint64 CarveBoundViolations = 0;
    uint64 FillBoundViolations = 0;
    bool bSdfBoundKnown = true;
    bool bHasSdfBound = false;
    float SdfBoundMin = FLT_MAX;
    float SdfBoundMax = -FLT_MAX;
    bool bHasSdfActual = false;
    float ActualSdfMin = FLT_MAX;
    float ActualSdfMax = -FLT_MAX;
    uint64 SdfBoundViolations = 0;
};

int32 ExploreEffectIndex(EVoxelOpEffect Effect)
{
    switch (Effect)
    {
    case EVoxelOpEffect::Identity:  return 0;
    case EVoxelOpEffect::CarveOnly: return 1;
    case EVoxelOpEffect::FillOnly:  return 2;
    case EVoxelOpEffect::Both:      return 3;
    default:                        return 0;
    }
}

void AccumulateExploreOpDiagnostic(
    const FVoxelOpStack::FOpBoxDiagnostic& Diagnostic,
    FExploreOpBoundsAggregate& Aggregate)
{
    Aggregate.Name = Diagnostic.Name;
    ++Aggregate.Blocks;
    Aggregate.Samples += Diagnostic.SampleCount;
    ++Aggregate.EffectCounts[ExploreEffectIndex(Diagnostic.Effect)];
    if (Diagnostic.bForced)
    {
        ++Aggregate.ForcedBoxes;
        if (FMath::IsFinite(Diagnostic.ForcedMargin))
        {
            Aggregate.MaxForcedMargin = FMath::Max(
                Aggregate.MaxForcedMargin, Diagnostic.ForcedMargin);
        }
        if (Diagnostic.ForcedVerdict == EVoxelTileClass::AllSolid)
        {
            ++Aggregate.ForcedSolidBoxes;
        }
        else if (Diagnostic.ForcedVerdict == EVoxelTileClass::AllAir)
        {
            ++Aggregate.ForcedAirBoxes;
        }
    }
    else
    {
        if (!ExploreIsKnownDensityBound(Diagnostic.MaxCarve))
        {
            Aggregate.bCarveBoundKnown = false;
            ++Aggregate.UnknownCarveBoundBoxes;
            if (Diagnostic.Effect == EVoxelOpEffect::CarveOnly
                || Diagnostic.Effect == EVoxelOpEffect::Both)
            {
                Aggregate.bRatioFinite = false;
            }
        }
        else
        {
            Aggregate.MaxCarveSupremum = FMath::Max(
                Aggregate.MaxCarveSupremum, Diagnostic.MaxCarve);
        }
        if (!ExploreIsKnownDensityBound(Diagnostic.MaxFill))
        {
            Aggregate.bFillBoundKnown = false;
            ++Aggregate.UnknownFillBoundBoxes;
            if (Diagnostic.Effect == EVoxelOpEffect::FillOnly
                || Diagnostic.Effect == EVoxelOpEffect::Both)
            {
                Aggregate.bRatioFinite = false;
            }
        }
        else
        {
            Aggregate.MaxFillSupremum = FMath::Max(
                Aggregate.MaxFillSupremum, Diagnostic.MaxFill);
        }
    }

    if (Diagnostic.bCarveBoundViolated) { ++Aggregate.CarveBoundViolations; }
    if (Diagnostic.bFillBoundViolated)  { ++Aggregate.FillBoundViolations; }

    if (Diagnostic.bHasDensityDelta)
    {
        Aggregate.bHasDensityActual = true;
        Aggregate.ActualDensityDeltaMin = FMath::Min(
            Aggregate.ActualDensityDeltaMin, Diagnostic.ActualDensityDeltaMin);
        Aggregate.ActualDensityDeltaMax = FMath::Max(
            Aggregate.ActualDensityDeltaMax, Diagnostic.ActualDensityDeltaMax);

        if (!Diagnostic.bForced)
        {
            const double ActualCarve = FMath::Max(
                0.0, -static_cast<double>(Diagnostic.ActualDensityDeltaMin));
            const double ActualFill = FMath::Max(
                0.0, static_cast<double>(Diagnostic.ActualDensityDeltaMax));
            double Ratio = 0.0;
            if (ExploreIsKnownDensityBound(Diagnostic.MaxCarve)
                && Diagnostic.MaxCarve > 0.0f)
            {
                Ratio = FMath::Max(Ratio, ActualCarve / Diagnostic.MaxCarve);
                if (ActualCarve > 1.0e-4)
                {
                    Aggregate.MaxConservativeRatio = FMath::Max(
                        Aggregate.MaxConservativeRatio,
                        static_cast<double>(Diagnostic.MaxCarve) / ActualCarve);
                }
            }
            else if (ActualCarve > 1.0e-4)
            {
                Aggregate.bRatioFinite = false;
            }
            if (ExploreIsKnownDensityBound(Diagnostic.MaxFill)
                && Diagnostic.MaxFill > 0.0f)
            {
                Ratio = FMath::Max(Ratio, ActualFill / Diagnostic.MaxFill);
                if (ActualFill > 1.0e-4)
                {
                    Aggregate.MaxConservativeRatio = FMath::Max(
                        Aggregate.MaxConservativeRatio,
                        static_cast<double>(Diagnostic.MaxFill) / ActualFill);
                }
            }
            else if (ActualFill > 1.0e-4)
            {
                Aggregate.bRatioFinite = false;
            }
            if (FMath::IsFinite(Ratio))
            {
                Aggregate.MaxDirectionalRatio = FMath::Max(
                    Aggregate.MaxDirectionalRatio, Ratio);
            }
            else
            {
                Aggregate.bRatioFinite = false;
            }
        }
    }

    if (Diagnostic.bHasSdfBound)
    {
        Aggregate.bHasSdfBound = true;
        Aggregate.SdfBoundMin = FMath::Min(
            Aggregate.SdfBoundMin, Diagnostic.SdfBoundMin);
        Aggregate.SdfBoundMax = FMath::Max(
            Aggregate.SdfBoundMax, Diagnostic.SdfBoundMax);
        if (Diagnostic.bHasSdfValue)
        {
            const float Epsilon = 1.0e-4f * FMath::Max(
                1.0f, FMath::Max(FMath::Abs(Diagnostic.SdfBoundMin),
                                  FMath::Abs(Diagnostic.SdfBoundMax)));
            if (Diagnostic.ActualSdfMin < Diagnostic.SdfBoundMin - Epsilon
                || Diagnostic.ActualSdfMax > Diagnostic.SdfBoundMax + Epsilon)
            {
                ++Aggregate.SdfBoundViolations;
            }
        }
    }
    else if (Diagnostic.bWritesSdf)
    {
        Aggregate.bSdfBoundKnown = false;
    }

    if (Diagnostic.bHasSdfValue)
    {
        Aggregate.bHasSdfActual = true;
        Aggregate.ActualSdfMin = FMath::Min(
            Aggregate.ActualSdfMin, Diagnostic.ActualSdfMin);
        Aggregate.ActualSdfMax = FMath::Max(
            Aggregate.ActualSdfMax, Diagnostic.ActualSdfMax);
    }
}

bool WriteExploreOpBoundsReport(
    const FExploreArguments& Arguments,
    const FExploreWorld& World,
    int32 BlocksTested,
    int32 RandomBlocksTested,
    int32 AllSolidBlocks,
    int32 AllAirBlocks,
    int32 MixedBlocks,
    const TArray<int32>& StackSolidKillerCounts,
    const TArray<int32>& StackAirKillerCounts,
    int32 StackVerdictMismatches,
    const TArray<FExploreOpBoundsAggregate>& Aggregates,
    FString& OutError)
{
    FString Json;
    TSharedRef<FExploreJsonWriter> Writer =
        TJsonWriterFactory<TCHAR, TCondensedJsonPrintPolicy<TCHAR>>::Create(&Json);
    Writer->WriteObjectStart();
    Writer->WriteValue(TEXT("schema_version"), 1);
    Writer->WriteValue(TEXT("tool"), TEXT("VoxelForgeExplore"));
    Writer->WriteValue(TEXT("purpose"), TEXT(
        "Conservative EffectOverBox/ClassifyBox bounds compared with brute-force Eval over the same "
        "one-voxel-halo domain of an 8-cell block."));
    Writer->WriteValue(TEXT("seed"), Arguments.Seed);
    Writer->WriteValue(TEXT("archetype"), ArchetypeName(Arguments.Archetype));
    Writer->WriteValue(TEXT("slot"), Arguments.Slot);
    Writer->WriteValue(TEXT("sample_step"), 1);
    Writer->WriteValue(TEXT("block_cells"), 8);
    Writer->WriteValue(TEXT("classifier_blocks_tested"), BlocksTested);
    Writer->WriteValue(TEXT("classifier_all_solid_blocks"), AllSolidBlocks);
    Writer->WriteValue(TEXT("classifier_all_air_blocks"), AllAirBlocks);
    Writer->WriteValue(TEXT("classifier_mixed_blocks"), MixedBlocks);
    Writer->WriteValue(TEXT("classifier_skip_rate"), BlocksTested > 0
        ? static_cast<double>(AllSolidBlocks + AllAirBlocks) / BlocksTested : 0.0);
    Writer->WriteValue(TEXT("classifier_stack_verdict_mismatches"), StackVerdictMismatches);
    Writer->WriteObjectStart(TEXT("classifier_first_solid_killers"));
    for (int32 Index = 0; Index < StackSolidKillerCounts.Num(); ++Index)
    {
        if (StackSolidKillerCounts[Index] <= 0) { continue; }
        Writer->WriteValue(
            FString::Printf(TEXT("op_%d"), Index), StackSolidKillerCounts[Index]);
    }
    Writer->WriteObjectEnd();
    Writer->WriteObjectStart(TEXT("classifier_first_air_killers"));
    for (int32 Index = 0; Index < StackAirKillerCounts.Num(); ++Index)
    {
        if (StackAirKillerCounts[Index] <= 0) { continue; }
        Writer->WriteValue(
            FString::Printf(TEXT("op_%d"), Index), StackAirKillerCounts[Index]);
    }
    Writer->WriteObjectEnd();
    Writer->WriteValue(TEXT("random_blocks_tested"), RandomBlocksTested);
    Writer->WriteValue(TEXT("bruteforce_block_index_min"), 1);
    Writer->WriteValue(TEXT("bruteforce_block_index_max_inclusive"), 14);
    Writer->WriteValue(TEXT("bounds_validated"), true);
    Writer->WriteValue(TEXT("target_bottom_world_z"), World.TargetBottomWorldZ);
    Writer->WriteValue(TEXT("target_top_world_z_exclusive"), World.TargetTopWorldZ);
    Writer->WriteArrayStart(TEXT("operators"));
    for (const FExploreOpBoundsAggregate& Aggregate : Aggregates)
    {
        Writer->WriteObjectStart();
        Writer->WriteValue(TEXT("name"), Aggregate.Name);
        Writer->WriteValue(TEXT("blocks"), static_cast<int64>(Aggregate.Blocks));
        Writer->WriteValue(TEXT("sample_points"), static_cast<int64>(Aggregate.Samples));
        Writer->WriteValue(TEXT("forced_boxes"), static_cast<int64>(Aggregate.ForcedBoxes));
        Writer->WriteValue(TEXT("forced_all_solid_boxes"), static_cast<int64>(Aggregate.ForcedSolidBoxes));
        Writer->WriteValue(TEXT("forced_all_air_boxes"), static_cast<int64>(Aggregate.ForcedAirBoxes));
        Writer->WriteValue(TEXT("forced_margin_supremum"), static_cast<double>(Aggregate.MaxForcedMargin));
        Writer->WriteObjectStart(TEXT("effect_counts"));
        Writer->WriteValue(TEXT("Identity"), static_cast<int64>(Aggregate.EffectCounts[0]));
        Writer->WriteValue(TEXT("CarveOnly"), static_cast<int64>(Aggregate.EffectCounts[1]));
        Writer->WriteValue(TEXT("FillOnly"), static_cast<int64>(Aggregate.EffectCounts[2]));
        Writer->WriteValue(TEXT("Both"), static_cast<int64>(Aggregate.EffectCounts[3]));
        Writer->WriteObjectEnd();
        Writer->WriteValue(TEXT("carve_bound_known"), Aggregate.bCarveBoundKnown);
        Writer->WriteValue(TEXT("unknown_carve_bound_boxes"),
                           static_cast<int64>(Aggregate.UnknownCarveBoundBoxes));
        Writer->WriteValue(TEXT("carve_bound_supremum"), static_cast<double>(
            Aggregate.bCarveBoundKnown ? Aggregate.MaxCarveSupremum : 0.0f));
        Writer->WriteValue(TEXT("fill_bound_known"), Aggregate.bFillBoundKnown);
        Writer->WriteValue(TEXT("unknown_fill_bound_boxes"),
                           static_cast<int64>(Aggregate.UnknownFillBoundBoxes));
        Writer->WriteValue(TEXT("fill_bound_supremum"), static_cast<double>(
            Aggregate.bFillBoundKnown ? Aggregate.MaxFillSupremum : 0.0f));
        Writer->WriteValue(TEXT("actual_density_delta_min"), static_cast<double>(
            Aggregate.bHasDensityActual ? Aggregate.ActualDensityDeltaMin : 0.0f));
        Writer->WriteValue(TEXT("actual_density_delta_max"), static_cast<double>(
            Aggregate.bHasDensityActual ? Aggregate.ActualDensityDeltaMax : 0.0f));
        Writer->WriteValue(TEXT("actual_carve_supremum"), Aggregate.bHasDensityActual
            ? static_cast<double>(FMath::Max(0.0f, -Aggregate.ActualDensityDeltaMin)) : 0.0);
        Writer->WriteValue(TEXT("actual_fill_supremum"), Aggregate.bHasDensityActual
            ? static_cast<double>(FMath::Max(0.0f, Aggregate.ActualDensityDeltaMax)) : 0.0);
        Writer->WriteValue(TEXT("directional_ratio_known"), Aggregate.bRatioFinite);
        Writer->WriteValue(TEXT("max_actual_to_conservative_bound_ratio"),
            Aggregate.bRatioFinite ? Aggregate.MaxDirectionalRatio : 0.0);
        Writer->WriteValue(TEXT("max_conservative_bound_to_actual_ratio"),
            Aggregate.bRatioFinite ? Aggregate.MaxConservativeRatio : 0.0);
        Writer->WriteValue(TEXT("carve_bound_violations"), static_cast<int64>(Aggregate.CarveBoundViolations));
        Writer->WriteValue(TEXT("fill_bound_violations"), static_cast<int64>(Aggregate.FillBoundViolations));
        Writer->WriteValue(TEXT("sdf_bound_known"), Aggregate.bSdfBoundKnown);
        Writer->WriteValue(TEXT("sdf_bound_min"), static_cast<double>(
            Aggregate.bHasSdfBound ? Aggregate.SdfBoundMin : 0.0f));
        Writer->WriteValue(TEXT("sdf_bound_max"), static_cast<double>(
            Aggregate.bHasSdfBound ? Aggregate.SdfBoundMax : 0.0f));
        Writer->WriteValue(TEXT("actual_sdf_min"), static_cast<double>(
            Aggregate.bHasSdfActual ? Aggregate.ActualSdfMin : 0.0f));
        Writer->WriteValue(TEXT("actual_sdf_max"), static_cast<double>(
            Aggregate.bHasSdfActual ? Aggregate.ActualSdfMax : 0.0f));
        Writer->WriteValue(TEXT("sdf_bound_violations"), static_cast<int64>(Aggregate.SdfBoundViolations));
        Writer->WriteObjectEnd();
    }
    Writer->WriteArrayEnd();
    Writer->WriteObjectEnd();

    if (!Writer->Close() || Json.IsEmpty()
        || !FFileHelper::SaveStringToFile(
            Json,
            *FPaths::Combine(Arguments.OutDirectory, TEXT("op_bounds.json")),
            FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        OutError = TEXT("Could not write op_bounds.json.");
        return false;
    }
    OutError.Reset();
    return true;
}

bool RunOpBounds(
    const FExploreArguments& Arguments,
    FExploreWorld& World,
    FExploreBudget& Budget,
    FString& OutError)
{
    if (Arguments.Archetype != ECaveGeneratorType::TunnelNetwork)
    {
        OutError = TEXT("opbounds requires archetype=TunnelNetwork.");
        return false;
    }

    const FIntVector TargetChunk(0, 0, World.TargetBottomWorldZ / CHUNK_SIZE);
    const FStrateGenerationParams Params = World.Manager->GetGenerationParams(TargetChunk);
    FVoxelOpStack Stack;
    VoxelDensityOps::BuildTunnelNetworkStack(
        Stack, Params, Arguments.Seed, World.Settings->OriginSpineRadius,
        World.Manager.Get());
    FVoxelOpContext Context;
    Context.ChunkCoord = TargetChunk;
    Context.Step = 1;
    Context.Seed = static_cast<uint32>(Arguments.Seed);
    Context.LayoutVersion = World.Manager->GetLayoutVersion();
    Context.WorldRadiusVoxels = World.Settings->WorldRadiusVoxels;
    Context.EdgeSealThickness = World.Settings->EdgeSealThickness;
    Context.StrateTopWorldZ = World.TargetTopWorldZ;
    Context.StrateBottomWorldZ = World.TargetBottomWorldZ;
    Stack.PrepareChunk(Context);

    constexpr int32 BlocksPerAxis = 16;
    constexpr int32 BlockCells = 8;
    const FIntVector RegionOrigin(-BlocksPerAxis * BlockCells / 2,
                                  -BlocksPerAxis * BlockCells / 2,
                                  World.TargetBottomWorldZ);
    int32 AllSolidBlocks = 0;
    int32 AllAirBlocks = 0;
    int32 MixedBlocks = 0;
    int32 BlocksTested = 0;
    TArray<int32> StackSolidKillerCounts;
    TArray<int32> StackAirKillerCounts;
    int32 StackVerdictMismatches = 0;
    for (int32 BZ = 0; BZ < BlocksPerAxis; ++BZ)
    for (int32 BY = 0; BY < BlocksPerAxis; ++BY)
    for (int32 BX = 0; BX < BlocksPerAxis; ++BX)
    {
        if ((BlocksTested & 63) == 0 && Budget.ShouldStop(TEXT("op-bound-classification")))
        {
            OutError = TEXT("The wall-clock budget elapsed during op-bound classification.");
            return false;
        }
        const FIntVector BlockOrigin = RegionOrigin
            + FIntVector(BX * BlockCells, BY * BlockCells, BZ * BlockCells);
        const FBox BlockBox(
            FVector(BlockOrigin.X - 1, BlockOrigin.Y - 1, BlockOrigin.Z - 1),
            FVector(BlockOrigin.X + BlockCells + 1,
                    BlockOrigin.Y + BlockCells + 1,
                    BlockOrigin.Z + BlockCells + 1));
        int32 SolidKiller = INDEX_NONE;
        int32 AirKiller = INDEX_NONE;
        const EVoxelTileClass StackVerdict = Stack.ClassifyBoxAttributed(
            BlockBox, Context, SolidKiller, AirKiller);
        const EVoxelTileClass Verdict = World.Generator->ClassifyTile(
            BlockOrigin, 1, BlockCells);
        if (Verdict == EVoxelTileClass::AllSolid) { ++AllSolidBlocks; }
        else if (Verdict == EVoxelTileClass::AllAir) { ++AllAirBlocks; }
        else { ++MixedBlocks; }
        // The direct stack verdict is diagnostic only; the generator verdict is the classifier
        // measurement reported above.
        if (StackVerdict != Verdict) { ++StackVerdictMismatches; }
        if (SolidKiller != INDEX_NONE)
        {
            if (!StackSolidKillerCounts.IsValidIndex(SolidKiller))
            {
                StackSolidKillerCounts.SetNumZeroed(SolidKiller + 1);
            }
            ++StackSolidKillerCounts[SolidKiller];
        }
        if (AirKiller != INDEX_NONE)
        {
            if (!StackAirKillerCounts.IsValidIndex(AirKiller))
            {
                StackAirKillerCounts.SetNumZeroed(AirKiller + 1);
            }
            ++StackAirKillerCounts[AirKiller];
        }
        ++BlocksTested;
    }

    constexpr int32 RandomBlocks = 256;
    TArray<FExploreOpBoundsAggregate> Aggregates;
    TArray<FVoxelOpStack::FOpBoxDiagnostic> Diagnostics;
    int32 RandomBlocksTested = 0;
    for (int32 SampleIndex = 0; SampleIndex < RandomBlocks; ++SampleIndex)
    {
        if ((SampleIndex & 15) == 0 && Budget.ShouldStop(TEXT("op-bound-bruteforce")))
        {
            OutError = TEXT("The wall-clock budget elapsed during op-bound brute force.");
            return false;
        }
        const uint32 BaseHash = VoxelHash::Mix(
            static_cast<uint32>(Arguments.Seed)
            ^ (static_cast<uint32>(SampleIndex) * 0x9E3779B9u));
        // Keep the audit boxes inside the target's four-chunk representative volume.  Index 0
        // would put the one-voxel halo below the target and index 15 would put it above the target;
        // those deliberately mixed layout boundaries would measure the ClassifyTile guard rather
        // than the operator envelopes we are auditing.
        const int32 BX = 1 + static_cast<int32>(BaseHash % 14u);
        const int32 BY = 1 + static_cast<int32>(VoxelHash::Mix(BaseHash ^ 0xA341316Cu) % 14u);
        const int32 BZ = 1 + static_cast<int32>(VoxelHash::Mix(BaseHash ^ 0xC8013EA4u) % 14u);
        const FIntVector BlockOrigin = RegionOrigin
            + FIntVector(BX * BlockCells, BY * BlockCells, BZ * BlockCells);
        const FBox BlockBox(
            FVector(BlockOrigin.X - 1, BlockOrigin.Y - 1, BlockOrigin.Z - 1),
            FVector(BlockOrigin.X + BlockCells + 1,
                    BlockOrigin.Y + BlockCells + 1,
                    BlockOrigin.Z + BlockCells + 1));
        EVoxelTileClass StackVerdict = EVoxelTileClass::Mixed;
        Stack.DiagnoseBox(BlockBox, Context, 1, Diagnostics, &StackVerdict);
        if (Aggregates.Num() == 0)
        {
            Aggregates.SetNum(Diagnostics.Num());
        }
        for (int32 OpIndex = 0; OpIndex < Diagnostics.Num(); ++OpIndex)
        {
            AccumulateExploreOpDiagnostic(Diagnostics[OpIndex], Aggregates[OpIndex]);
        }
        ++RandomBlocksTested;
    }

    if (!WriteExploreOpBoundsReport(
            Arguments, World, BlocksTested, RandomBlocksTested,
            AllSolidBlocks, AllAirBlocks, MixedBlocks,
            StackSolidKillerCounts, StackAirKillerCounts,
            StackVerdictMismatches, Aggregates, OutError))
    {
        return false;
    }
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeOpBounds] blocks=%d all_solid=%d all_air=%d mixed=%d skip_rate=%.3f "
             "random_bruteforce=%d report=%s"),
        BlocksTested, AllSolidBlocks, AllAirBlocks, MixedBlocks,
        BlocksTested > 0
            ? static_cast<double>(AllSolidBlocks + AllAirBlocks) / BlocksTested : 0.0,
        RandomBlocksTested,
        *FPaths::Combine(Arguments.OutDirectory, TEXT("op_bounds.json")));
    return true;
}

} // namespace

UVoxelForgeExploreCommandlet::UVoxelForgeExploreCommandlet()
{
    IsClient = false;
    IsServer = false;
    IsEditor = true;
    LogToConsole = true;
}

int32 RunExploreCase(const FString& Params, FString* OutJson)
{
    const double MainStartSeconds = FPlatformTime::Seconds();
    UE_LOG(LogTemp, Display, TEXT("[VoxelForgeExplore] invoked: %s"), FCommandLine::Get());

    FExploreArguments Arguments;
    FString Error;
    if (!ParseArguments(Params, Arguments, Error))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] %s"), *Error);
        return 1;
    }

    // A commandlet can run several fresh manager lifetimes in one process. Release completed
    // immutable proof caches from the preceding case before constructing this one.
    VoxelDensityOps::TrimSharedRoomGraphCache();

    // Every case starts from a disabled, empty diagnostic state.  The world/cache objects are
    // local to this invocation and their owner/lifetime keys prevent stale worker caches from
    // serving the next case's generation.
    VoxelDensityProfile::Reset();
    VoxelDensityProfile::SetMode(
        Arguments.IsDensityProfilingEnabled()
            ? ExploreProfileMode(Arguments)
            : VoxelDensityProfile::EMode::Disabled,
        VoxelDensityProfile::DefaultSampleInterval);
    if (!IFileManager::Get().MakeDirectory(*Arguments.OutDirectory, true))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] Could not create output directory '%s'."),
            *Arguments.OutDirectory);
        return 1;
    }

    FExploreBudget Budget(
        MainStartSeconds,
        static_cast<double>(Arguments.BudgetMinutes) * 60.0);

    const double SetupStartSeconds = FPlatformTime::Seconds();
    FExploreWorld World;
    if (!World.Build(Arguments, Error))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] %s"), *Error);
        return 1;
    }
    const double SetupSeconds = FPlatformTime::Seconds() - SetupStartSeconds;

    FExploreStackSamplerSession StackSamplerSession;
    if (Arguments.bSampleStacks
        && !StackSamplerSession.Start(
            Arguments.SampleStacksIntervalUs, Arguments.OutDirectory))
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeExplore] stack sampler was requested but could not be started."));
        return 1;
    }

    FExploreRunOutput Output;
    bool bRequestedModeFailed = false;
    if (Arguments.bTunnelCoreProbe)
    {
        const double Start = FPlatformTime::Seconds();
        const bool bProbeOk = !Budget.bTruncated
            && RunTunnelCoreProbe(Arguments, World, Output.TunnelCoreProbe, Budget);
        if (!bProbeOk && !Budget.bTruncated)
        {
            bRequestedModeFailed = true;
        }
        if (bProbeOk && !Budget.bTruncated)
        {
            Budget.CompleteMode(TEXT("tunnelcoreprobe"));
        }
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeExplore] tunnel core probe %.3fs (%s)"),
            FPlatformTime::Seconds() - Start,
            bProbeOk ? TEXT("ok")
                : (Budget.bTruncated ? TEXT("truncated") : TEXT("error")));
    }
    if (Arguments.bDensitySlice)
    {
        const double Start = FPlatformTime::Seconds();
        const bool bDensitySliceOk = !Budget.bTruncated
            && RunDensitySlice(Arguments, World, Output.DensitySlice, Budget);
        if (!bDensitySliceOk && !Budget.bTruncated)
        {
            bRequestedModeFailed = true;
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeExplore] density slice failed: %s"),
                *Output.DensitySlice.RefusalReason);
        }
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeExplore] density slice %.3fs (%s)"),
            FPlatformTime::Seconds() - Start,
            bDensitySliceOk ? TEXT("ok")
                : (Budget.bTruncated ? TEXT("truncated") : TEXT("error")));
    }
    if (Arguments.bOpBounds)
    {
        const double Start = FPlatformTime::Seconds();
        const bool bOpBoundsOk = !Budget.bTruncated
            && RunOpBounds(Arguments, World, Budget, Error);
        if (!bOpBoundsOk && !Budget.bTruncated)
        {
            bRequestedModeFailed = true;
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] opbounds failed: %s"), *Error);
        }
        if (bOpBoundsOk && !Budget.bTruncated)
        {
            Budget.CompleteMode(TEXT("opbounds"));
        }
        UE_LOG(LogTemp, Display, TEXT("[VoxelForgeExplore] opbounds %.3fs (%s)"),
            FPlatformTime::Seconds() - Start,
            bOpBoundsOk ? TEXT("ok") : (Budget.bTruncated ? TEXT("truncated") : TEXT("error")));
    }

    if (Arguments.bProfileLod)
    {
        const FIntVector ProbeOrigin(0, 0, World.TargetBottomWorldZ);
        const int32 FullRes = World.Settings
            ? FMath::Max(1, World.Settings->FullResClipLevels)
            : 2;
        const int32 CoarseCells = World.Settings
            ? FMath::Clamp(World.Settings->CoarseTileCells, 4, CHUNK_SIZE)
            : 16;
        const int32 CutMin = World.Settings
            ? World.Settings->GetEffectiveStrateContentCutMinLevel()
            : 9;
        for (int32 Level = 0; Level <= 4; ++Level)
        {
            // Match AVoxelWorld::LoadTile exactly: the probe is a production tile at this LOD,
            // including the configured coarse sample count.  Using 1<<Level here would measure
            // a denser mesh than the game generates at levels >= FullResClipLevels.
            const int32 Extent = CHUNK_SIZE << Level;
            const int32 Cells = Level < FullRes ? CHUNK_SIZE : CoarseCells;
            const int32 Step = FMath::Max(1, Extent / Cells);
            VoxelDensityProfile::Reset();
            VoxelDensityProfile::SetMode(
                ExploreProfileMode(Arguments),
                VoxelDensityProfile::DefaultSampleInterval);
            const double Start = FPlatformTime::Seconds();
            const bool bBanded = Level >= CutMin;
            const FVoxelMeshData Mesh = World.Mesher->GenerateMesh(
                ProbeOrigin, Step, Cells, nullptr,
                bBanded ? World.TargetBottomWorldZ : INT32_MIN,
                bBanded ? World.TargetTopWorldZ - 1 : INT32_MAX);
            const double Seconds = FPlatformTime::Seconds() - Start;
            const VoxelDensityProfile::FSnapshot Profile = VoxelDensityProfile::Snapshot();
            const int32 DensityIndex = static_cast<int32>(VoxelDensityProfile::EBucket::GetDensityAt);
            const uint64 Calls = Profile.Calls[DensityIndex];
            const uint64 Lookups = Profile.Counters[static_cast<int32>(VoxelDensityProfile::ECounter::TunnelCacheLookup)];
            const uint64 Hits = Profile.Counters[static_cast<int32>(VoxelDensityProfile::ECounter::TunnelCacheHit)];
            const uint64 SdfBuilds = Profile.Counters[static_cast<int32>(VoxelDensityProfile::ECounter::SdfCacheBuild)];
            const double DensityUs = static_cast<double>(Profile.WallCycles[DensityIndex])
                * FPlatformTime::GetSecondsPerCycle64() * 1.0e6;
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeLODProfile] level=%d step=%d cells=%d banded=%d seconds=%.6f density_calls=%llu "
                     "density_us_per_call=%.3f sdf_builds=%llu cache_lookups=%llu cache_hits=%llu cache_misses=%llu "
                     "hit_rate=%.3f vertices=%d triangles=%d mesh_empty=%d"),
                Level, Step, Cells, bBanded ? 1 : 0, Seconds,
                static_cast<unsigned long long>(Calls),
                Calls > 0 ? DensityUs / static_cast<double>(Calls) : 0.0,
                static_cast<unsigned long long>(SdfBuilds),
                static_cast<unsigned long long>(Lookups),
                static_cast<unsigned long long>(Hits),
                static_cast<unsigned long long>(Profile.Counters[static_cast<int32>(VoxelDensityProfile::ECounter::TunnelCacheMiss)]),
                Lookups > 0 ? static_cast<double>(Hits) / static_cast<double>(Lookups) : 0.0,
                Mesh.Vertices.Num(), Mesh.Triangles.Num() / 3,
                Mesh.IsEmpty() ? 1 : 0);
        }
        if (Arguments.IsDensityProfilingEnabled())
        {
            VoxelDensityProfile::Reset();
            VoxelDensityProfile::SetMode(
                ExploreProfileMode(Arguments),
                VoxelDensityProfile::DefaultSampleInterval);
        }
        else
        {
            VoxelDensityProfile::SetMode(VoxelDensityProfile::EMode::Disabled);
        }
    }

    if (Budget.ShouldStop(TEXT("setup")))
    {
        UE_LOG(LogTemp, Warning,
            TEXT("[VoxelForgeExplore] setup consumed the wall-clock budget; no mode was started."));
    }
    FExploreWalkOutput RenderSeedWalk;
    const FExploreWalkOutput* CameraSeedWalk = nullptr;
    if (Arguments.bWalk)
    {
        const double Start = FPlatformTime::Seconds();
        const bool bWalkOk = RunWalk(Arguments, World, Output.Walk, Budget);
        Output.WalkSeconds = FPlatformTime::Seconds() - Start;
        if (!bWalkOk && !Budget.bTruncated)
        {
            bRequestedModeFailed = true;
        }
        UE_LOG(LogTemp, Display, TEXT("[VoxelForgeExplore] walk %.3fs (%s)"),
            Output.WalkSeconds, *Output.Walk.Status);
        CameraSeedWalk = &Output.Walk;
        if (bWalkOk && !Budget.bTruncated)
        {
            Budget.CompleteMode(TEXT("walk"));
        }
    }
    else if (Arguments.bRender)
    {
        if (Arguments.bRenderCameraOverride)
        {
            // Controlled diagnostic renders can supply a player-fit seed captured from a baseline
            // run. This keeps the mesh region, camera pose, and raster target identical while a
            // single generator writer is toggled. The density guard in RunRender still refuses a
            // stale/inside-rock pose.
            RenderSeedWalk.CameraSeedPoses.Add(Arguments.RenderCamera);
            RenderSeedWalk.CameraSeedSources.Add(TEXT("render_camera_override"));
            RenderSeedWalk.Status = TEXT("override");
            Output.WalkSeconds = 0.0;
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeExplore] render camera seed override (%.3f, %.3f, %.3f)"),
                Arguments.RenderCamera.X, Arguments.RenderCamera.Y, Arguments.RenderCamera.Z);
        }
        else
        {
            // A render-only invocation still has to obey the inside-walkable-space contract. Run
            // the same focused walk as a private seed pass; it is intentionally omitted from the
            // render-only JSON so the selected mode remains render.
            const double Start = FPlatformTime::Seconds();
            const bool bWalkOk = RunWalk(Arguments, World, RenderSeedWalk, Budget);
            Output.WalkSeconds = FPlatformTime::Seconds() - Start;
            if (!bWalkOk && !Budget.bTruncated)
            {
                bRequestedModeFailed = true;
            }
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeExplore] render camera seed walk %.3fs (%s)"),
                Output.WalkSeconds, *RenderSeedWalk.Status);
        }
        CameraSeedWalk = &RenderSeedWalk;
        // Keep the private render seed capture available to the run-level shared-grid report;
        // the walk object is still omitted from the public JSON when walk was not requested.
        Output.Walk = MoveTemp(RenderSeedWalk);
        CameraSeedWalk = &Output.Walk;
    }

    // A profile report gets a genuine unprofiled reference for the same canonical mesh region.
    // The reference world is fresh, profiling is disabled for it, and its geometry hash is
    // compared with the profiled world below.  This is deliberately a diagnostic second pass;
    // it cannot affect the profiled world's generation or its deterministic output.
    if (Arguments.IsDensityProfilingEnabled()
        && (Arguments.bRender || Arguments.bExport)
        && (CameraSeedWalk != nullptr || Arguments.bExport)
        && !Budget.bTruncated)
    {
        Output.ProfilerComparison.Scope = TEXT("canonical_mesh_export");
        VoxelDensityProfile::SetMode(VoxelDensityProfile::EMode::Disabled);
        FExploreWorld ReferenceWorld;
        FString ReferenceError;
        if (ReferenceWorld.Build(Arguments, ReferenceError))
        {
            FExploreBudget ReferenceBudget(MainStartSeconds, Budget.LimitSeconds);
            const double ReferenceStart = FPlatformTime::Seconds();
            if (EnsureExploreMesh(
                    Arguments, ReferenceWorld, CameraSeedWalk, ReferenceBudget, ReferenceError)
                && ReferenceWorld.bExploreMeshComplete)
            {
                Output.ProfilerComparison.bAvailable = true;
                Output.ProfilerComparison.UnprofiledSeconds = ReferenceWorld.ExploreMeshSeconds;
                Output.ProfilerComparison.UnprofiledGeometryHash = ReferenceWorld.ExploreGeometryHash;
            }
            else
            {
                UE_LOG(LogTemp, Warning,
                    TEXT("[VoxelForgeProfiler] unprofiled reference failed after %.3fs: %s"),
                    FPlatformTime::Seconds() - ReferenceStart, *ReferenceError);
            }
        }
        else
        {
            UE_LOG(LogTemp, Warning,
                TEXT("[VoxelForgeProfiler] could not build unprofiled reference world: %s"),
                *ReferenceError);
        }
        VoxelDensityProfile::Reset();
        VoxelDensityProfile::SetMode(
            ExploreProfileMode(Arguments),
            VoxelDensityProfile::DefaultSampleInterval);
    }
    if (Arguments.bRender)
    {
        const double Start = FPlatformTime::Seconds();
        bool bRenderOk = false;
        if (!Budget.bTruncated && CameraSeedWalk != nullptr)
        {
            bRenderOk = RunRender(
                Arguments, World, *CameraSeedWalk, Output.Render, Budget);
        }
        if (!bRenderOk && !Budget.bTruncated)
        {
            bRequestedModeFailed = true;
        }
        if (Budget.bTruncated && Output.Render.Status.IsEmpty())
        {
            Output.Render.Status = TEXT("truncated");
            Output.Render.bTruncated = true;
            Output.Render.RefusalReason = TEXT("The wall-clock budget stopped before rendering.");
        }
        if (bRenderOk && !Budget.bTruncated)
        {
            Budget.CompleteMode(TEXT("render"));
        }
        UE_LOG(LogTemp, Display, TEXT("[VoxelForgeExplore] render %.3fs (%s)"),
            FPlatformTime::Seconds() - Start, *Output.Render.Status);
    }
    if (Arguments.bFailureFocusRender && Arguments.bRender && Arguments.bWalk
        && !Budget.bTruncated)
    {
        const double Start = FPlatformTime::Seconds();
        if (!RunFailureBoundaryRender(Arguments, World, Output.Walk, Output.Render, Budget))
        {
            if (!Budget.bTruncated)
            {
                bRequestedModeFailed = true;
            }
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeExplore] failure-focus render could not produce a boundary image."));
        }
        else
        {
            UE_LOG(LogTemp, Display, TEXT("[VoxelForgeExplore] failure-focus render %.3fs (ok)"),
                FPlatformTime::Seconds() - Start);
        }
    }
    if (Arguments.bExport)
    {
        const double Start = FPlatformTime::Seconds();
        const bool bExportOk = !Budget.bTruncated
            && RunExport(Arguments, World, CameraSeedWalk, Output.Export, Budget);
        if (!bExportOk && !Budget.bTruncated)
        {
            bRequestedModeFailed = true;
        }
        if (Budget.bTruncated && Output.Export.Status.IsEmpty())
        {
            Output.Export.Status = TEXT("truncated");
            Output.Export.bTruncated = true;
            Output.Export.RefusalReason = TEXT("The wall-clock budget stopped before export.");
        }
        if (bExportOk && !Budget.bTruncated)
        {
            Budget.CompleteMode(TEXT("export"));
        }
        UE_LOG(LogTemp, Display, TEXT("[VoxelForgeExplore] export %.3fs (%s)"),
            FPlatformTime::Seconds() - Start, *Output.Export.Status);
    }

    // Stop before the report is assembled, while World still owns the generation state. This
    // guarantees that the sampler's summary describes only this case and that all worker stacks
    // have been released before the commandlet tears the world down.
    StackSamplerSession.Stop();

    // A phase can finish just inside its own check and cross the deadline while its artifact is
    // being closed. Mark that state before serialising the report so the JSON never claims a full
    // run after the budget has actually expired.
    Budget.ShouldStop(TEXT("report"));
    if (Budget.bTruncated)
    {
        if (Arguments.bWalk && Output.Walk.Status.IsEmpty())
        {
            Output.Walk.Status = TEXT("truncated");
            Output.Walk.RefusalReason = TEXT("The wall-clock budget stopped before walk completion.");
        }
        UE_LOG(LogTemp, Warning,
            TEXT("[VoxelForgeExplore] truncated during %s after %.3fs; completed modes=%s"),
            *Budget.TruncatedDuring,
            Budget.ElapsedSeconds(),
            *FString::Join(Budget.CompletedModes, TEXT(",")));
    }
    Output.BudgetSeconds = Budget.LimitSeconds;
    Output.ElapsedSeconds = FPlatformTime::Seconds() - MainStartSeconds;
    Output.bTruncated = Budget.bTruncated;
    Output.TruncatedDuring = Budget.TruncatedDuring;
    Output.CompletedModes = Budget.CompletedModes;

    Output.Profile = VoxelDensityProfile::Snapshot();
    Output.bHasProfile = true;
    if (Arguments.IsDensityProfilingEnabled())
    {
        if (Output.ProfilerComparison.bAvailable)
        {
            Output.ProfilerComparison.ProfiledSeconds = World.ExploreMeshSeconds;
            Output.ProfilerComparison.ProfiledGeometryHash = World.ExploreGeometryHash;
            Output.ProfilerComparison.DiscrepancySeconds =
                Output.ProfilerComparison.ProfiledSeconds
                - Output.ProfilerComparison.UnprofiledSeconds;
            Output.ProfilerComparison.DiscrepancyPercent =
                Output.ProfilerComparison.UnprofiledSeconds > 0.0
                    ? Output.ProfilerComparison.DiscrepancySeconds
                        * 100.0 / Output.ProfilerComparison.UnprofiledSeconds
                    : 0.0;
            Output.ProfilerComparison.Ratio =
                Output.ProfilerComparison.UnprofiledSeconds > 0.0
                    ? Output.ProfilerComparison.ProfiledSeconds
                        / Output.ProfilerComparison.UnprofiledSeconds
                    : 0.0;
            Output.ProfilerComparison.bGeometryEqual =
                !Output.ProfilerComparison.ProfiledGeometryHash.IsEmpty()
                && Output.ProfilerComparison.ProfiledGeometryHash
                    == Output.ProfilerComparison.UnprofiledGeometryHash;
            const bool bWithinTarget = FMath::Abs(Output.ProfilerComparison.DiscrepancyPercent) <= 20.0;
            const bool bSelfCheckPassed = bWithinTarget
                && Output.ProfilerComparison.bGeometryEqual;
            Output.ProfilerComparison.SelfCheck = bSelfCheckPassed ? TEXT("passed") : TEXT("FAILED");
            if (bSelfCheckPassed)
            {
                UE_LOG(
                    LogTemp, Display,
                    TEXT("[VoxelForgeProfiler] profiled_total=%.6fs unprofiled_total=%.6fs "
                         "discrepancy=%.2f%% ratio=%.3fx geometry_equal=%s self_check=%s"),
                    Output.ProfilerComparison.ProfiledSeconds,
                    Output.ProfilerComparison.UnprofiledSeconds,
                    Output.ProfilerComparison.DiscrepancyPercent,
                    Output.ProfilerComparison.Ratio,
                    Output.ProfilerComparison.bGeometryEqual ? TEXT("yes") : TEXT("no"),
                    *Output.ProfilerComparison.SelfCheck);
            }
            else
            {
                UE_LOG(
                    LogTemp, Error,
                    TEXT("[VoxelForgeProfiler] profiled_total=%.6fs unprofiled_total=%.6fs "
                         "discrepancy=%.2f%% ratio=%.3fx geometry_equal=%s self_check=%s"),
                    Output.ProfilerComparison.ProfiledSeconds,
                    Output.ProfilerComparison.UnprofiledSeconds,
                    Output.ProfilerComparison.DiscrepancyPercent,
                    Output.ProfilerComparison.Ratio,
                    Output.ProfilerComparison.bGeometryEqual ? TEXT("yes") : TEXT("no"),
                    *Output.ProfilerComparison.SelfCheck);
            }
            if (!bSelfCheckPassed)
            {
                bRequestedModeFailed = true;
            }
        }
        else
        {
            Output.ProfilerComparison.Scope = TEXT("canonical_mesh_export");
            Output.ProfilerComparison.SelfCheck = TEXT("not_available");
            UE_LOG(LogTemp, Error,
                TEXT("[VoxelForgeProfiler] self-check could not obtain an unprofiled reference."));
            bRequestedModeFailed = true;
        }
    }

    // Build the payload twice before adding the assertion itself. This is deliberately a string
    // comparison over a fixed-order writer, not a TMap/pretty-printer whose key order could drift.
    const FString Payload = BuildExploreJson(Arguments, World, Output, false, 0);
    const FString PayloadRepeat = BuildExploreJson(Arguments, World, Output, false, 0);
    if (Payload.IsEmpty() || PayloadRepeat.IsEmpty())
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] JSON writer failed before report creation."));
        return 1;
    }
    // Hash the exact UTF-8 representation that is written to disk. This keeps the reported
    // digest independent of TCHAR width (and therefore meaningful when the same run is compared
    // across editor platforms).
    FTCHARToUTF8 PayloadUtf8(*Payload);
    const uint32 PayloadCrc32 = FCrc::MemCrc32(PayloadUtf8.Get(), PayloadUtf8.Length());
    const bool bPayloadRepeatEqual = Payload == PayloadRepeat;
    FString Json = BuildExploreJson(
        Arguments, World, Output, bPayloadRepeatEqual, PayloadCrc32);
    const FString JsonRepeat = BuildExploreJson(
        Arguments, World, Output, bPayloadRepeatEqual, PayloadCrc32);
    if (Json.IsEmpty() || JsonRepeat.IsEmpty())
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] JSON writer failed during report creation."));
        return 1;
    }
    const bool bFinalRepeatEqual = Json == JsonRepeat;
    if (!bFinalRepeatEqual)
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeExplore] deterministic JSON assertion failed before write."));
        bRequestedModeFailed = true;
        Json = BuildExploreJson(Arguments, World, Output, false, PayloadCrc32);
    }

    const FString ReportPath = FPaths::Combine(Arguments.OutDirectory, TEXT("explore.json"));
    if (!FFileHelper::SaveStringToFile(
            Json,
            *ReportPath,
            FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] Could not write '%s'."), *ReportPath);
        return 1;
    }
    if (OutJson != nullptr)
    {
        *OutJson = Json;
    }

    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeExplore] setup %.3fs, total %.3fs; report=%s; json_deterministic=%s"),
        SetupSeconds,
        FPlatformTime::Seconds() - MainStartSeconds,
        *ReportPath,
        (bPayloadRepeatEqual && bFinalRepeatEqual) ? TEXT("yes") : TEXT("no"));

    if (Arguments.IsDensityProfilingEnabled())
    {
        const VoxelDensityProfile::FSnapshot Profile = VoxelDensityProfile::Snapshot();
        const double CycleToMicroseconds = FPlatformTime::GetSecondsPerCycle64() * 1.0e6;
        const uint64 DensityCalls = Profile.Calls[static_cast<int32>(VoxelDensityProfile::EBucket::GetDensityAt)];
        const uint64 DensityCycles = Profile.WallCycles[static_cast<int32>(VoxelDensityProfile::EBucket::GetDensityAt)];
        const double DensityTotalUs = static_cast<double>(DensityCycles) * CycleToMicroseconds;
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeDensityProfile] total calls=%llu total_us=%.3f us_per_call=%.6f"),
            static_cast<unsigned long long>(DensityCalls), DensityTotalUs,
            DensityCalls > 0 ? DensityTotalUs / static_cast<double>(DensityCalls) : 0.0);

        const uint64 CacheTotalStaticBytes = Profile.TunnelCacheStaticBytes
            + Profile.RoomGraphCacheStaticBytes;
        const uint64 CacheTotalDynamicBytes = Profile.TunnelCacheDynamicBytes
            + Profile.RoomGraphCacheDynamicBytes;
        const uint64 CacheTotalBytes = CacheTotalStaticBytes + CacheTotalDynamicBytes;
        const uint64 CacheWorkers = FMath::Max(
            Profile.TunnelCacheWorkers, Profile.RoomGraphCacheWorkers);
        const uint64 CacheValidEntries = Profile.TunnelCacheValidEntries
            + Profile.RoomGraphCacheValidEntries;
        const uint64 CacheEntryBytes = Profile.TunnelCacheEntryBytes
            + Profile.RoomGraphCacheEntryBytes;
        const uint64 CacheCapacityEntries = Profile.TunnelCacheCapacityEntries
            + Profile.RoomGraphCacheCapacityEntries;
        const uint64 CacheLargestEntryBytes = FMath::Max(
            Profile.TunnelCacheLargestEntryBytes,
            Profile.RoomGraphCacheLargestEntryBytes);
        const uint64 CacheLargestWorkerBytes = FMath::Max(
            Profile.TunnelCacheLargestWorkerBytes,
            Profile.RoomGraphCacheLargestWorkerBytes);
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeCacheMemory] workers=%llu capacity_entries=%llu valid_entries=%llu "
                 "static_bytes=%llu dynamic_bytes=%llu total_bytes=%llu "
                 "avg_valid_entry_bytes=%.1f largest_entry_bytes=%llu "
                 "avg_worker_bytes=%.1f largest_worker_bytes=%llu "
                 "tunnel_avg_entry_bytes=%.1f tunnel_largest_entry_bytes=%llu "
                 "tunnel_largest_worker_valid=%llu "
                 "roomgraph_avg_entry_bytes=%.1f roomgraph_largest_entry_bytes=%llu "
                 "roomgraph_largest_worker_valid=%llu "
                 "tunnel_workers=%llu tunnel_capacity=%llu tunnel_valid=%llu "
                 "tunnel_static=%llu tunnel_dynamic=%llu roomgraph_workers=%llu "
                 "roomgraph_capacity=%llu roomgraph_valid=%llu roomgraph_static=%llu "
                 "roomgraph_dynamic=%llu"),
            static_cast<unsigned long long>(CacheWorkers),
            static_cast<unsigned long long>(CacheCapacityEntries),
            static_cast<unsigned long long>(CacheValidEntries),
            static_cast<unsigned long long>(CacheTotalStaticBytes),
            static_cast<unsigned long long>(CacheTotalDynamicBytes),
            static_cast<unsigned long long>(CacheTotalBytes),
            CacheValidEntries > 0
                ? static_cast<double>(CacheEntryBytes) / static_cast<double>(CacheValidEntries)
                : 0.0,
            static_cast<unsigned long long>(CacheLargestEntryBytes),
            CacheWorkers > 0
                ? static_cast<double>(CacheTotalBytes) / static_cast<double>(CacheWorkers)
                : 0.0,
            static_cast<unsigned long long>(CacheLargestWorkerBytes),
            Profile.TunnelCacheValidEntries > 0
                ? static_cast<double>(Profile.TunnelCacheEntryBytes)
                    / static_cast<double>(Profile.TunnelCacheValidEntries)
                : 0.0,
            static_cast<unsigned long long>(Profile.TunnelCacheLargestEntryBytes),
            static_cast<unsigned long long>(Profile.TunnelCacheLargestWorkerValidEntries),
            Profile.RoomGraphCacheValidEntries > 0
                ? static_cast<double>(Profile.RoomGraphCacheEntryBytes)
                    / static_cast<double>(Profile.RoomGraphCacheValidEntries)
                : 0.0,
            static_cast<unsigned long long>(Profile.RoomGraphCacheLargestEntryBytes),
            static_cast<unsigned long long>(Profile.RoomGraphCacheLargestWorkerValidEntries),
            static_cast<unsigned long long>(Profile.TunnelCacheWorkers),
            static_cast<unsigned long long>(Profile.TunnelCacheCapacityEntries),
            static_cast<unsigned long long>(Profile.TunnelCacheValidEntries),
            static_cast<unsigned long long>(Profile.TunnelCacheStaticBytes),
            static_cast<unsigned long long>(Profile.TunnelCacheDynamicBytes),
            static_cast<unsigned long long>(Profile.RoomGraphCacheWorkers),
            static_cast<unsigned long long>(Profile.RoomGraphCacheCapacityEntries),
            static_cast<unsigned long long>(Profile.RoomGraphCacheValidEntries),
            static_cast<unsigned long long>(Profile.RoomGraphCacheStaticBytes),
            static_cast<unsigned long long>(Profile.RoomGraphCacheDynamicBytes));

        const VoxelDensityProfile::EBucket DensityPhases[] = {
            VoxelDensityProfile::EBucket::DensityPrologue,
            VoxelDensityProfile::EBucket::DensityCore,
            VoxelDensityProfile::EBucket::DensityDisturbances,
            VoxelDensityProfile::EBucket::DensityStructuralPosts,
            VoxelDensityProfile::EBucket::DensityBoundarySeal,
            VoxelDensityProfile::EBucket::DensityDiffLayer,
            VoxelDensityProfile::EBucket::DensityTail,
        };
        uint64 DensityAttributionCycles = 0;
        uint64 DensityAttributionCalls = 0;
        for (const VoxelDensityProfile::EBucket Phase : DensityPhases)
        {
            const int32 PhaseIndex = static_cast<int32>(Phase);
            DensityAttributionCycles += Profile.WallCycles[PhaseIndex];
            DensityAttributionCalls += Profile.Calls[PhaseIndex];
        }
        const double DensityAttributionUs =
            static_cast<double>(DensityAttributionCycles) * CycleToMicroseconds;
        const double DensityUnattributedUs = DensityTotalUs - DensityAttributionUs;
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeDensityProfile] attribution_sum_us=%.3f unattributed_us=%.3f "
                 "coverage=%.2f%% phase_calls=%llu"),
            DensityAttributionUs, DensityUnattributedUs,
            DensityTotalUs > 0.0 ? DensityAttributionUs * 100.0 / DensityTotalUs : 0.0,
            static_cast<unsigned long long>(DensityAttributionCalls));

        for (int32 Index = 0; Index < VoxelDensityProfile::CounterCount; ++Index)
        {
            const VoxelDensityProfile::ECounter Counter =
                static_cast<VoxelDensityProfile::ECounter>(Index);
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeDensityProfile] counter=%s value=%llu per_density_call=%.3f"),
                VoxelDensityProfile::CounterName(Counter),
                static_cast<unsigned long long>(Profile.Counters[Index]),
                DensityCalls > 0
                    ? static_cast<double>(Profile.Counters[Index])
                        / static_cast<double>(DensityCalls)
                    : 0.0);
        }

        for (int32 Index = 0; Index < VoxelDensityProfile::BucketCount; ++Index)
        {
            const uint64 Calls = Profile.Calls[Index];
            if (Calls == 0 || Index == static_cast<int32>(VoxelDensityProfile::EBucket::GetDensityAt))
            {
                continue;
            }
            const double TotalUs = static_cast<double>(Profile.WallCycles[Index]) * CycleToMicroseconds;
            UE_LOG(LogTemp, Display,
                TEXT("[VoxelForgeDensityProfile] op=%s calls=%llu total_us=%.3f us_per_call=%.6f"),
                VoxelDensityProfile::BucketName(static_cast<VoxelDensityProfile::EBucket>(Index)),
                static_cast<unsigned long long>(Calls), TotalUs,
                TotalUs / static_cast<double>(Calls));
        }

        const VoxelDensityProfile::EBucket MesherBuckets[] = {
            VoxelDensityProfile::EBucket::MesherDensityGrid,
            VoxelDensityProfile::EBucket::MesherCellClassification,
            VoxelDensityProfile::EBucket::MesherGradientNormals,
            VoxelDensityProfile::EBucket::MesherVertexInterpolation,
            VoxelDensityProfile::EBucket::MesherStreamBuilding,
            VoxelDensityProfile::EBucket::MesherOther,
        };
        uint64 MesherAttributionCycles = 0;
        uint64 MesherAttributionCalls = 0;
        for (const VoxelDensityProfile::EBucket Bucket : MesherBuckets)
        {
            const int32 BucketIndex = static_cast<int32>(Bucket);
            MesherAttributionCycles += Profile.WallCycles[BucketIndex];
            MesherAttributionCalls += Profile.Calls[BucketIndex];
        }
        const int32 MesherTotalIndex = static_cast<int32>(
            VoxelDensityProfile::EBucket::MesherGenerateMesh);
        const double MesherTotalUs = static_cast<double>(
            Profile.WallCycles[MesherTotalIndex]) * CycleToMicroseconds;
        const double MesherAttributionUs = static_cast<double>(
            MesherAttributionCycles) * CycleToMicroseconds;
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeMesherProfile] total_calls=%llu total_us=%.3f "
                 "attribution_sum_us=%.3f unattributed_us=%.3f coverage=%.2f%% "
                 "phase_calls=%llu"),
            static_cast<unsigned long long>(Profile.Calls[MesherTotalIndex]),
            MesherTotalUs, MesherAttributionUs, MesherTotalUs - MesherAttributionUs,
            MesherTotalUs > 0.0 ? MesherAttributionUs * 100.0 / MesherTotalUs : 0.0,
            static_cast<unsigned long long>(MesherAttributionCalls));
        VoxelDensityProfile::SetMode(VoxelDensityProfile::EMode::Disabled);
    }
    VoxelDensityOps::ReportSharedRoomGraphCacheFootprint();
    VoxelDensityOps::TrimSharedRoomGraphCache();
    // Per-case isolation boundary.  The UObject world dies with this function; worker-local
    // caches are keyed by the fresh generator/manager lifetime and the diagnostics are reset before
    // the next case.  No case may inherit profiler counters or a live profiler mode.
    VoxelDensityProfile::Reset();
    VoxelDensityProfile::SetMode(VoxelDensityProfile::EMode::Disabled);
    return bRequestedModeFailed ? 2 : 0;
}

namespace
{
FString SanitizeBatchCaseId(const FString& InId, int32 Index)
{
    FString Result;
    for (const TCHAR Character : InId)
    {
        const bool bAsciiAlphaNumeric =
            (Character >= TEXT('a') && Character <= TEXT('z'))
            || (Character >= TEXT('A') && Character <= TEXT('Z'))
            || (Character >= TEXT('0') && Character <= TEXT('9'));
        if (bAsciiAlphaNumeric || Character == TEXT('_') || Character == TEXT('-'))
        {
            Result.AppendChar(Character);
        }
    }
    if (Result.IsEmpty())
    {
        Result = FString::Printf(TEXT("case_%03d"), Index);
    }
    return Result;
}

bool JsonNumber(const TSharedPtr<FJsonObject>& Object, const TCHAR* Key, double& OutValue)
{
    if (!Object.IsValid() || !Object->HasField(Key))
    {
        return false;
    }
    OutValue = Object->GetNumberField(Key);
    return FMath::IsFinite(OutValue);
}

bool JsonString(const TSharedPtr<FJsonObject>& Object, const TCHAR* Key, FString& OutValue)
{
    if (!Object.IsValid() || !Object->HasField(Key))
    {
        return false;
    }
    OutValue = Object->GetStringField(Key);
    return true;
}

bool JsonBool(const TSharedPtr<FJsonObject>& Object, const TCHAR* Key, bool& OutValue)
{
    if (!Object.IsValid() || !Object->HasField(Key))
    {
        return false;
    }
    OutValue = Object->GetBoolField(Key);
    return true;
}

bool BuildBatchCaseParams(
    const TSharedPtr<FJsonObject>& Case,
    const FString& CaseOutDirectory,
    FString& OutParams,
    FString& OutError)
{
    if (!Case.IsValid())
    {
        OutError = TEXT("Each batch case must be a JSON object.");
        return false;
    }

    double Number = 0.0;
    int32 Seed = 0;
    if (JsonNumber(Case, TEXT("seed"), Number))
    {
        Seed = FMath::RoundToInt(Number);
    }
    FString Archetype = TEXT("Maze");
    JsonString(Case, TEXT("archetype"), Archetype);
    int32 Slot = 4;
    if (JsonNumber(Case, TEXT("slot"), Number))
    {
        Slot = FMath::RoundToInt(Number);
    }
    int32 ExportSize = DefaultExportSize;
    if (JsonNumber(Case, TEXT("export_size"), Number))
    {
        ExportSize = FMath::RoundToInt(Number);
    }
    int32 ExportStep = DefaultExportStep;
    if (JsonNumber(Case, TEXT("export_step"), Number)
        || JsonNumber(Case, TEXT("step"), Number))
    {
        ExportStep = FMath::RoundToInt(Number);
    }
    if (JsonNumber(Case, TEXT("lod"), Number))
    {
        const int32 Lod = FMath::RoundToInt(Number);
        if (Lod < 0 || Lod > 3)
        {
            OutError = TEXT("case.lod must be in [0,3].");
            return false;
        }
        ExportStep = 1 << Lod;
    }

    bool bReuseDensityGrid = true;
    JsonBool(Case, TEXT("density_grid_reuse"), bReuseDensityGrid);
    bool bBlockEarlyOut = false;
    JsonBool(Case, TEXT("block_early_out"), bBlockEarlyOut);
    int32 MeshMinBatchSize = 1;
    if (JsonNumber(Case, TEXT("mesh_min_batch_size"), Number))
    {
        MeshMinBatchSize = FMath::Clamp(FMath::RoundToInt(Number), 1, 64);
    }

    FString Modes = TEXT("export");
    JsonString(Case, TEXT("modes"), Modes);
    bool bProfileDensity = false;
    JsonBool(Case, TEXT("profile_density"), bProfileDensity);
    bool bProfileDensityFull = false;
    JsonBool(Case, TEXT("profile_density_full"), bProfileDensityFull);
    bProfileDensity |= bProfileDensityFull;
    bool bPerfAttribution = false;
    JsonBool(Case, TEXT("perf_attribution"), bPerfAttribution);
    bool bSampleStacks = false;
    JsonBool(Case, TEXT("sample_stacks"), bSampleStacks);
    int32 SampleStacksIntervalUs = static_cast<int32>(FVoxelStackSampler::DefaultIntervalUs);
    if (JsonNumber(Case, TEXT("sample_stacks_interval_us"), Number))
    {
        SampleStacksIntervalUs = FMath::RoundToInt(Number);
        bSampleStacks = true;
    }
    bool bProfileLod = false;
    JsonBool(Case, TEXT("profile_lod"), bProfileLod);
    bool bOpBounds = false;
    JsonBool(Case, TEXT("op_bounds"), bOpBounds);
    bool bFailureFocus = false;
    JsonBool(Case, TEXT("failure_focus_render"), bFailureFocus);
    bool bTunnelFloorEnabled = true;
    const bool bHasTunnelFloorEnabled = JsonBool(
        Case, TEXT("tunnel_floor_enabled"), bTunnelFloorEnabled);
    bool bTunnelFloorTerracing = true;
    const bool bHasTunnelFloorTerracing = JsonBool(
        Case, TEXT("tunnel_floor_terracing"), bTunnelFloorTerracing);

    OutParams = FString::Printf(
        TEXT("-seed=%d -archetype=%s -slot=%d -modes=%s "
             "-exportsize=%d -exportstep=%d -densitygridreuse=%d "
             "-blockearlyout=%d -meshminbatch=%d "
             "-failurefocus=%d -out=\"%s\""),
        Seed, *Archetype, Slot, *Modes,
        ExportSize, ExportStep, bReuseDensityGrid ? 1 : 0,
        bBlockEarlyOut ? 1 : 0, MeshMinBatchSize,
        bFailureFocus ? 1 : 0, *CaseOutDirectory);

    if (bHasTunnelFloorEnabled)
    {
        OutParams += FString::Printf(
            TEXT(" -tunnelfloor=%d"), bTunnelFloorEnabled ? 1 : 0);
    }
    if (bHasTunnelFloorTerracing)
    {
        OutParams += FString::Printf(
            TEXT(" -tunnelfloorterracing=%d"), bTunnelFloorTerracing ? 1 : 0);
    }

    if (bProfileDensity)
    {
        OutParams += bProfileDensityFull
            ? TEXT(" -profiledensityfull")
            : TEXT(" -profiledensity");
    }
    if (bPerfAttribution)
    {
        OutParams += TEXT(" -perfattribution");
    }
    if (bSampleStacks)
    {
        OutParams += FString::Printf(
            TEXT(" -samplestacks=%d"), SampleStacksIntervalUs);
    }
    if (bProfileLod)
    {
        OutParams += TEXT(" -profilelod");
    }
    if (bOpBounds)
    {
        OutParams += TEXT(" -opbounds");
    }

    const TPair<const TCHAR*, const TCHAR*> IntegerFields[] = {
        { TEXT("render_width"), TEXT("renderwidth") },
        { TEXT("render_height"), TEXT("renderheight") },
        { TEXT("max_walk_cells"), TEXT("maxwalkcells") },
    };
    for (const auto& Field : IntegerFields)
    {
        if (JsonNumber(Case, Field.Key, Number))
        {
            OutParams += FString::Printf(TEXT(" -%s=%d"),
                Field.Value, FMath::RoundToInt(Number));
        }
    }
    const TPair<const TCHAR*, const TCHAR*> FloatFields[] = {
        { TEXT("render_step"), TEXT("renderstep") },
        { TEXT("render_max_distance"), TEXT("rendermaxdistance") },
        { TEXT("surface_roughness"), TEXT("surfaceroughness") },
        { TEXT("roughness_frequency"), TEXT("roughnessfrequency") },
        { TEXT("room_mouth_rise_strength"), TEXT("roommouthrise") },
        { TEXT("room_mouth_rise_blend_voxels"), TEXT("roommouthriseblend") },
        { TEXT("tunnel_floor_step_height"), TEXT("tunnelfloorstep") },
        { TEXT("tunnel_floor_max_ledge_height"), TEXT("tunnelfloormaxledge") },
        { TEXT("tunnel_floor_gentle_slope"), TEXT("tunnelfloorgentle") },
    };
    for (const auto& Field : FloatFields)
    {
        if (JsonNumber(Case, Field.Key, Number))
        {
            OutParams += FString::Printf(TEXT(" -%s=%.9g"), Field.Value, Number);
        }
    }

    FString RoughnessType;
    if (JsonString(Case, TEXT("roughness_noise_type"), RoughnessType))
    {
        OutParams += FString::Printf(TEXT(" -roughnesstype=%s"), *RoughnessType);
    }

    const TPair<const TCHAR*, const TCHAR*> IntegerFloorFields[] = {
        { TEXT("tunnel_floor_ledge_count"), TEXT("tunnelfloorledges") },
        { TEXT("tunnel_floor_max_ledges"), TEXT("tunnelfloormaxledges") },
    };
    for (const auto& Field : IntegerFloorFields)
    {
        if (JsonNumber(Case, Field.Key, Number))
        {
            OutParams += FString::Printf(TEXT(" -%s=%d"),
                Field.Value, FMath::RoundToInt(Number));
        }
    }

    return true;
}

int32 RunBatch(const FString& Params)
{
    FString BatchPath;
    FString OutText;
    if (!FParse::Value(*Params, TEXT("batch="), BatchPath)
        || !FParse::Value(*Params, TEXT("out="), OutText))
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeExplore] batch requires -batch=<json> and an absolute -out=<Saved path>."));
        return 1;
    }
    if (FPaths::IsRelative(OutText))
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeExplore] batch -out must be absolute and under '%s'."),
            *VoxelForgeSavedRoot());
        return 1;
    }
    const FString BatchOutDirectory = FPaths::ConvertRelativePathToFull(OutText);
    if (!IsUnderVoxelForgeSaved(BatchOutDirectory))
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeExplore] batch -out must be under '%s' (got '%s')."),
            *VoxelForgeSavedRoot(), *BatchOutDirectory);
        return 1;
    }
    if (!IFileManager::Get().MakeDirectory(*BatchOutDirectory, true))
    {
        UE_LOG(LogTemp, Error,
            TEXT("[VoxelForgeExplore] could not create batch output '%s'."),
            *BatchOutDirectory);
        return 1;
    }

    BatchPath = FPaths::ConvertRelativePathToFull(BatchPath);
    FString BatchText;
    if (!FFileHelper::LoadFileToString(BatchText, *BatchPath))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] could not read batch file '%s'."), *BatchPath);
        return 1;
    }
    TSharedPtr<FJsonObject> Root;
    const TSharedRef<TJsonReader<>> Reader = TJsonReaderFactory<>::Create(BatchText);
    if (!FJsonSerializer::Deserialize(Reader, Root) || !Root.IsValid())
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] batch file is not valid JSON."));
        return 1;
    }
    const TArray<TSharedPtr<FJsonValue>>* Cases = nullptr;
    if (!Root->TryGetArrayField(TEXT("cases"), Cases) || Cases == nullptr || Cases->Num() == 0)
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] batch JSON needs a non-empty 'cases' array."));
        return 1;
    }
    if (Cases->Num() > 256)
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] batch is capped at 256 cases."));
        return 1;
    }

    double BatchBudgetMinutes = 29.0;
    double Number = 0.0;
    if (JsonNumber(Root, TEXT("budget_minutes"), Number))
    {
        BatchBudgetMinutes = Number;
    }
    if (FParse::Value(*Params, TEXT("batchbudget="), Number))
    {
        BatchBudgetMinutes = Number;
    }
    BatchBudgetMinutes = FMath::Clamp(BatchBudgetMinutes, 0.01, 30.0);
    const double BatchStartSeconds = FPlatformTime::Seconds();
    bool bTruncated = false;
    int32 CompletedCases = 0;
    int32 FailedCases = 0;
    TSet<FString> UsedCaseIds;
    TArray<TSharedPtr<FJsonValue>> CaseReports;
    CaseReports.Reserve(Cases->Num());

    for (int32 Index = 0; Index < Cases->Num(); ++Index)
    {
        const double RemainingSeconds = BatchBudgetMinutes * 60.0
            - (FPlatformTime::Seconds() - BatchStartSeconds);
        if (RemainingSeconds <= 0.25)
        {
            bTruncated = true;
            break;
        }
        const TSharedPtr<FJsonObject> Case = (*Cases)[Index]->AsObject();
        FString CaseId;
        JsonString(Case, TEXT("id"), CaseId);
        CaseId = SanitizeBatchCaseId(CaseId, Index);
        const FString BaseCaseId = CaseId;
        int32 Suffix = 1;
        while (UsedCaseIds.Contains(CaseId))
        {
            CaseId = FString::Printf(TEXT("%s_%d"), *BaseCaseId, Suffix++);
        }
        UsedCaseIds.Add(CaseId);
        FString CaseOutDirectory = FPaths::Combine(BatchOutDirectory, TEXT("cases"), CaseId);
        FString CaseParams;
        FString CaseError;
        if (!BuildBatchCaseParams(Case, CaseOutDirectory, CaseParams, CaseError))
        {
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] batch case %d (%s): %s"),
                Index, *CaseId, *CaseError);
            TSharedPtr<FJsonObject> CaseReport = MakeShared<FJsonObject>();
        CaseReport->SetStringField(TEXT("case_id"), CaseId);
        CaseReport->SetNumberField(TEXT("case_index"), Index);
        CaseReport->SetNumberField(TEXT("case_exit_code"), 1);
        CaseReport->SetStringField(TEXT("status"), TEXT("invalid"));
            CaseReport->SetStringField(TEXT("error"), CaseError);
            CaseReports.Add(MakeShared<FJsonValueObject>(CaseReport));
            ++CompletedCases;
            ++FailedCases;
            continue;
        }

        double CaseBudgetMinutes = FMath::Min(25.0, RemainingSeconds / 60.0);
        if (JsonNumber(Case, TEXT("budget_minutes"), Number))
        {
            CaseBudgetMinutes = FMath::Min(CaseBudgetMinutes, Number);
        }
        CaseBudgetMinutes = FMath::Clamp(CaseBudgetMinutes, 0.01, 30.0);
        CaseParams += FString::Printf(TEXT(" -budget=%.9g"), CaseBudgetMinutes);

        FString CaseJson;
        const int32 CaseResult = RunExploreCase(CaseParams, &CaseJson);
        TSharedPtr<FJsonObject> CaseReport;
        const TSharedRef<TJsonReader<>> CaseReader = TJsonReaderFactory<>::Create(CaseJson);
        if (!FJsonSerializer::Deserialize(CaseReader, CaseReport) || !CaseReport.IsValid())
        {
            CaseReport = MakeShared<FJsonObject>();
            CaseReport->SetStringField(TEXT("error"), TEXT("case did not produce a JSON report"));
        }
        CaseReport->SetStringField(TEXT("case_id"), CaseId);
        CaseReport->SetNumberField(TEXT("case_index"), Index);
        CaseReport->SetNumberField(TEXT("case_exit_code"), CaseResult);
        CaseReports.Add(MakeShared<FJsonValueObject>(CaseReport));
        ++CompletedCases;
        if (CaseResult != 0)
        {
            ++FailedCases;
        }

        // RunExploreCase owns a complete transient UObject world.  Release that case's strong
        // roots before starting the next one and collect now; otherwise a batch retains every
        // completed mesh/settings/manager graph until the commandlet exits, making peak RSS grow
        // with the number of cases even though no report needs those objects afterward.
        CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
    }

    TSharedPtr<FJsonObject> BatchReport = MakeShared<FJsonObject>();
    BatchReport->SetNumberField(TEXT("schema_version"), 2);
    BatchReport->SetStringField(TEXT("tool"), TEXT("VoxelForgeExplore"));
    BatchReport->SetBoolField(TEXT("batch"), true);
    BatchReport->SetStringField(TEXT("input_file"), BatchPath);
    BatchReport->SetStringField(TEXT("output_directory"), BatchOutDirectory);
    BatchReport->SetNumberField(TEXT("budget_minutes"), BatchBudgetMinutes);
    BatchReport->SetNumberField(TEXT("elapsed_seconds"), FPlatformTime::Seconds() - BatchStartSeconds);
    BatchReport->SetBoolField(TEXT("truncated"), bTruncated);
    BatchReport->SetNumberField(TEXT("completed_cases"), CompletedCases);
    BatchReport->SetNumberField(TEXT("failed_cases"), FailedCases);
    BatchReport->SetArrayField(TEXT("cases"), MoveTemp(CaseReports));

    FString BatchJson;
    const TSharedRef<TJsonWriter<>> Writer = TJsonWriterFactory<>::Create(&BatchJson);
    if (!FJsonSerializer::Serialize(BatchReport.ToSharedRef(), Writer)
        || !FFileHelper::SaveStringToFile(
            BatchJson,
            *FPaths::Combine(BatchOutDirectory, TEXT("batch.json")),
            FFileHelper::EEncodingOptions::ForceUTF8WithoutBOM))
    {
        UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] could not write batch.json."));
        return 1;
    }
    UE_LOG(LogTemp, Display,
        TEXT("[VoxelForgeExplore] batch completed=%d failed=%d truncated=%s report=%s"),
        CompletedCases, FailedCases, bTruncated ? TEXT("yes") : TEXT("no"),
        *FPaths::Combine(BatchOutDirectory, TEXT("batch.json")));
    return FailedCases > 0 || bTruncated ? 2 : 0;
}
}

int32 UVoxelForgeExploreCommandlet::Main(const FString& Params)
{
    const bool bRegionEvalSwitch = FParse::Param(*Params, TEXT("regioneval"));
    int32 RegionEvalFlag = 0;
    const bool bRegionEvalValue = FParse::Value(*Params, TEXT("regioneval="), RegionEvalFlag);
    if (bRegionEvalSwitch || (bRegionEvalValue && RegionEvalFlag != 0))
    {
        return RunRegionEval(Params);
    }

    FString SymbolizeCsvPath;
    if (FParse::Value(*Params, TEXT("symbolizestacks="), SymbolizeCsvPath))
    {
        FString SymbolizedOutputPath;
        FString SymbolPath;
        FParse::Value(*Params, TEXT("symbolizedout="), SymbolizedOutputPath);
        FParse::Value(*Params, TEXT("symbolpath="), SymbolPath);

        FString SummaryPath;
        FString Error;
        if (!VoxelForgeOfflineStackSymbolizer::Run(
                SymbolizeCsvPath, SymbolizedOutputPath, SymbolPath, SummaryPath, Error))
        {
            UE_LOG(LogTemp, Error, TEXT("[VoxelForgeExplore] offline stack symbolization failed: %s"),
                *Error);
            return 2;
        }
        UE_LOG(LogTemp, Display,
            TEXT("[VoxelForgeExplore] offline stack symbolization completed summary=%s"),
            *SummaryPath);
        return 0;
    }

    FString BatchPath;
    if (FParse::Value(*Params, TEXT("batch="), BatchPath))
    {
        return RunBatch(Params);
    }
    return RunExploreCase(Params, nullptr);
}