skip: sound whole-tile proofs for legacy FI/TN/VS fields (L74); FI -30%, TN -22%

The compiled-analytic stratum interval now certifies a legacy tile uniform only when it stays
beyond the detail envelope (and smooth-min slack for solid) with no intersecting primitive,
edit, native field, composer candidate, passage or active transition; everything else fails
closed. The stream layer uses the proof for whole-tile skips; legacy sub-tile skips stay off
(two block proofs failed the falsifier in TN).

Falsifier: full-grid reference vs skip-enabled run, identical mesh/payload/topology hashes on
every tile of all four owner views, Clang and GCC, W1/W8/W12; 20-camera sweep per strate,
0 violations; a too-tight control changed 3/184/233/238 tiles and was caught.
Whole view (8 workers): SW 2.61->2.48, FI 7.18->5.05, TN 5.97->4.63, VS 2.70->2.40 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Core/include/VoxelForgeCore/VoxelForgeCore.h

@@ -1759,6 +1759,9 @@ namespace VoxelForgeCore
         std::int32_t bandMinZVoxel = -2147483647 - 1;
         std::int32_t bandMaxZVoxel = 2147483647;
         bool hashDensity = false;
+        // Falsifier mode: retain mesh/topology hashes while permitting proven empty tiles
+        // to skip their density lattice. The density hash of such a skipped tile is empty.
+        bool allowUniformSkipsWhenHashing = false;
         bool captureDensitySamples = false;
         // Diagnostic only; materialize the full density lattice even when block proofs
         // establish that the tile has no surface.

Standalone/Core/src/ShapeWorldInternal.h

@@ -18,6 +18,7 @@
 #include <cmath>
 #include <cstdint>
 #include <cstdio>
+#include <cstdlib>
 #include <limits>
 #include <memory>
 #include <mutex>
@@ -2155,6 +2156,7 @@ public:
         EVoxelTileClass Verdict=EVoxelTileClass::Mixed;
         bool bNativeSurface=false;
         bool bUnknown=false;
+        bool bSkipSafe=false;
     };
     struct FClassificationThreadStats
     {
@@ -5965,6 +5967,14 @@ public:
             return SharedDensitySource->ClassifyBoxDetailed(Origin,Step,Cells,bUseNativeLatticeProof);
         using Clock=std::chrono::steady_clock;
         const auto Start=Clock::now();
+        static const bool bL74TightNegativeControl=[]
+        {
+            const char* Value=std::getenv("VOXELFORGE_L74_TIGHT_PROOF_CONTROL");
+            const bool Enabled=Value&&Value[0]=='1'&&Value[1]=='\0';
+            if(Enabled)
+                std::printf("[L74NegativeControl] enabled=1 bound=base-sign-only-detail-and-primitive-envelope-omitted\n");
+            return Enabled;
+        }();
         const int32 Pad=std::max(Step,1);
         int32 BMin[3]={Origin.X-Pad,Origin.Y-Pad,Origin.Z-Pad};
         int32 BMax[3]={Origin.X+(Cells+1)*Step,Origin.Y+(Cells+1)*Step,Origin.Z+(Cells+1)*Step};
@@ -6025,15 +6035,19 @@ public:
             bCaveOtherStrateOverlap=bCavesOverlap
                 &&(bSurfaceOverlap||bIslandOverlap||bLegacyOverlap);
         }
-        const auto Finish=[&](EVoxelTileClass Verdict,bool bUnknown=false)
+        const auto Finish=[&](EVoxelTileClass Verdict,bool bUnknown=false,
+                              bool bLegacyAnalyticProof=false)
         {
             const bool bNative=(bSurfaceOverlap&&!bOtherStrateOverlap)
                 ||(bIslandOverlap&&!bIslandOtherStrateOverlap)
                 ||(bCavesOverlap&&!bCaveOtherStrateOverlap);
-            FBoxClassification Result{Verdict,bNative,bUnknown};
+            const bool bUniform=Verdict==EVoxelTileClass::AllAir
+                ||Verdict==EVoxelTileClass::AllSolid;
+            FBoxClassification Result{Verdict,bNative,bUnknown,
+                bLegacyAnalyticProof||(bNative&&!bUnknown&&bUniform)};
             auto& Counts=ThreadClassificationStats();
             Counts.Milliseconds+=std::chrono::duration<double,std::milli>(Clock::now()-Start).count();
-            if(!Result.bNativeSurface||bUnknown)++Counts.UnknownBoxes;
+            if(bUnknown)++Counts.UnknownBoxes;
             else if(Verdict==EVoxelTileClass::AllSolid)++Counts.SolidBoxes;
             else if(Verdict==EVoxelTileClass::AllAir)++Counts.AirBoxes;
             else ++Counts.MixedBoxes;
@@ -6076,7 +6090,7 @@ public:
                 static_cast<std::int64_t>(BMax[1])*Q,
                 static_cast<std::int64_t>(BMax[2])*Q};
             caveCandidates=BuildCavernFeatureTileList(minimum,maximum);
-            if(!caveCandidates.empty()&&!bCavesOverlap)
+            if(!caveCandidates.empty()&&!bCavesOverlap&&!bL74TightNegativeControl)
                 return Finish(EVoxelTileClass::Mixed,true);
         }
         if(ResolvedPassageIntersectsBox(BMin,BMax))
@@ -6116,6 +6130,110 @@ public:
                 return Finish(EVoxelTileClass::Mixed,true);
             }
         }
+        // Boundary transitions can replace otherwise-air density with a solid seal and
+        // can append a separate face mesh. Their authored bands were checked above; this
+        // expanded window also covers the maximum XY displacement at every active seam.
+        if(ResolvedLayout&&Owner&&Owner->CoreVoxelSizeMicrons>0)
+        {
+            const double ZMinimumMicrometres=static_cast<double>(BMin[2])
+                *Owner->CoreVoxelSizeMicrons;
+            const double ZMaximumMicrometres=static_cast<double>(BMax[2])
+                *Owner->CoreVoxelSizeMicrons;
+            for(const auto& Upper:ResolvedLayout->strates)
+            {
+                const auto* Lower=FindResolvedLayoutStratumByOrder(Upper.order+1);
+                if(!Lower||!IsResolvedLayoutTransitionActive(Upper))continue;
+                const double MaximumDisplacement=
+                    ResolvedTransitionMaximumFaceDisplacementMicrometres(Upper,*Lower);
+                const double WindowMinimum=std::min(Upper.bedrock.bottomMicrometres,
+                    Lower->ceiling.bottomMicrometres)-MaximumDisplacement;
+                const double WindowMaximum=std::max(Upper.bedrock.topMicrometres,
+                    Lower->ceiling.topMicrometres)+MaximumDisplacement;
+                if(ZMaximumMicrometres>=WindowMinimum
+                    &&ZMinimumMicrometres<=WindowMaximum)
+                    return Finish(EVoxelTileClass::Mixed,true);
+            }
+        }
+        const auto TryLegacyAnalyticProof=[&]() -> std::optional<EVoxelTileClass>
+        {
+            // The shared base shape may use packed occupancy, while its selected legacy
+            // field remains the compiled strata distance plus bounded primitive/detail
+            // terms. SurfaceWorld op stacks, native adapters, and any active composer
+            // feature fail closed and keep using their existing path.
+            if(!WorldAssembly||!Owner||!Owner->Manager
+                ||!ResolvedLayout||!Owner->Generator||bSurfaceOverlap||bCavesOverlap
+                ||(!bL74TightNegativeControl
+                    &&(!stampCandidates.empty()||!caveCandidates.empty()))
+                ||!EditBrushes.empty()||LayerRanges.empty()
+                ||ActiveSpatialBinSize<=0)return std::nullopt;
+            const double LayoutWidth=GetResolvedLayoutChunkWidthVoxels();
+            if(!(LayoutWidth>0.0)||!std::isfinite(LayoutWidth))return std::nullopt;
+            const int32 FirstChunk=FMath::FloorToInt(static_cast<float>(BMin[2])/LayoutWidth);
+            const int32 LastChunk=FMath::FloorToInt(static_cast<float>(BMax[2])/LayoutWidth);
+            for(int32 ChunkZ=FirstChunk;ChunkZ<=LastChunk;++ChunkZ)
+            {
+                const FBoundStratumField* Bound=FindBoundStratumForChunk(ChunkZ);
+                if(!Bound||Bound->Kind==FBoundStratumField::EKind::SurfaceWorld)
+                    return std::nullopt;
+                if(Bound->Kind==FBoundStratumField::EKind::FloatingIslands)
+                {
+                    // A missing FI plan is the owner's compiled-analytic fallback. Any
+                    // installed plan selects the native FI field and is outside this proof.
+                    if(Bound->IslandPlan)return std::nullopt;
+                }
+                if(Bound->Kind==FBoundStratumField::EKind::Caves)return std::nullopt;
+            }
+            for(int32 BZ=FloorDiv(BMin[2],ActiveSpatialBinSize);
+                BZ<=FloorDiv(BMax[2],ActiveSpatialBinSize);++BZ)
+            for(int32 BY=FloorDiv(BMin[1],ActiveSpatialBinSize);
+                BY<=FloorDiv(BMax[1],ActiveSpatialBinSize);++BY)
+            for(int32 BX=FloorDiv(BMin[0],ActiveSpatialBinSize);
+                BX<=FloorDiv(BMax[0],ActiveSpatialBinSize);++BX)
+            {
+                const auto It=SpatialBins.find({BX,BY,BZ});
+                if(It==SpatialBins.end())continue;
+                for(const uint32 Id:It->second)
+                {
+                    const FPrimitive& Primitive=Primitives[Id];
+                    bool Overlap=true;
+                    for(int32 Axis=0;Axis<3;++Axis)
+                        Overlap=Overlap
+                            &&Primitive.Max[Axis]+DetailBand>=BMin[Axis]
+                            &&Primitive.Min[Axis]-DetailBand<=BMax[Axis];
+                    if(Overlap&&!bL74TightNegativeControl)return std::nullopt;
+                }
+            }
+
+            const FInterval& Layer=LayerRanges.front();
+            if(Layer.Hi<=Layer.Lo)return std::nullopt;
+            const auto BaseAt=[&](double Z)
+            {return std::min(Z-static_cast<double>(Layer.Lo),
+                static_cast<double>(Layer.Hi)-Z);};
+            const double Z0=static_cast<double>(BMin[2]);
+            const double Z1=static_cast<double>(BMax[2]);
+            const double Base0=BaseAt(Z0),Base1=BaseAt(Z1);
+            const double BaseMinimum=std::min(Base0,Base1);
+            double BaseMaximum=std::max(Base0,Base1);
+            const double Peak=(static_cast<double>(Layer.Lo)+Layer.Hi)*0.5;
+            if(Peak>=Z0&&Peak<=Z1)BaseMaximum=std::max(BaseMaximum,BaseAt(Peak));
+            // With no active primitive, smooth-min sees only its +100000 sentinel;
+            // its largest possible downward correction is 12/6 = 2 voxels. Keep
+            // the entire resulting field outside the measured detail support (4.125).
+            constexpr double DetailSupport=DetailSupremum+0.125;
+            constexpr double SmoothMinSlack=StrataCaveBlendRadius/6.0;
+            constexpr double SafetyEpsilon=1.0e-3;
+            const double SolidMargin=bL74TightNegativeControl
+                ?SafetyEpsilon:DetailSupport+SmoothMinSlack+SafetyEpsilon;
+            const double AirMargin=bL74TightNegativeControl
+                ?SafetyEpsilon:DetailSupport+SafetyEpsilon;
+            if(BaseMinimum>SolidMargin)
+                return EVoxelTileClass::AllSolid;
+            if(BaseMaximum<-AirMargin)
+                return EVoxelTileClass::AllAir;
+            return std::nullopt;
+        };
+        if(const auto LegacyVerdict=TryLegacyAnalyticProof())
+            return Finish(*LegacyVerdict,false,true);
         // A box crossing recipes cannot use one field interval; unknown composition stays Mixed.
         // Une boite qui traverse plusieurs recettes reste Mixed, car l'intervalle d'un seul champ ne suffit pas.
         if(bBadPlan||(bSurfaceOverlap&&(bIslandOverlap||bOtherStrateOverlap))

Standalone/Core/src/VoxelForgeCore.cpp

@@ -2356,6 +2356,7 @@ namespace VoxelForgeCore
                 static_cast<std::int64_t>(origin.Y+extent)*SubvoxelsPerVoxel);
         }
         bool bNativeSurfaceTile=false;
+        bool bTileProofSkipSafe=false;
         bool bNativeSurfaceBandSafe=false;
         double classificationColumnComputeMilliseconds=0.0;
         if(bHasWorldAssembly)
@@ -2367,6 +2368,7 @@ namespace VoxelForgeCore
                 VoxelForgeCore::Heightfield2D::threadColumnCacheStats().columnComputeMilliseconds
                     -columnMillisecondsBeforeClassification);
             bNativeSurfaceTile=Classification.bNativeSurface;
+            bTileProofSkipSafe=Classification.bSkipSafe;
             if(options.profileMesherStages)
                 out.diagnostics.nativeSurfaceTile=bNativeSurfaceTile;
             // NativeSurfaceDensityAt consumes only the bounded manifest heightfield and its
@@ -2374,7 +2376,7 @@ namespace VoxelForgeCore
             // unknown; edits and cross-strate tiles are still excluded below.
             // NativeSurfaceDensityAt ne consomme que le champ et les volumes bornes du manifeste.
             bNativeSurfaceBandSafe=bNativeSurfaceTile;
-            if(bNativeSurfaceTile)
+            if(bNativeSurfaceTile||bTileProofSkipSafe)
             {
                 out.diagnostics.tileWasClassified=true;
                 switch(Classification.bUnknown?EVoxelTileClass::Mixed:Classification.Verdict)
@@ -2383,12 +2385,30 @@ namespace VoxelForgeCore
                     case EVoxelTileClass::AllAir:out.diagnostics.tileClass=TileClass::allAir;break;
                     case EVoxelTileClass::Mixed:out.diagnostics.tileClass=TileClass::mixed;break;
                 }
-                if((out.diagnostics.tileClass==TileClass::allSolid
+                if(bTileProofSkipSafe&&(out.diagnostics.tileClass==TileClass::allSolid
                     ||out.diagnostics.tileClass==TileClass::allAir)
-                    &&!options.hashDensity&&!options.captureDensitySamples&&!bNeedsFarShell
+                    &&(!options.hashDensity||options.allowUniformSkipsWhenHashing)
+                    &&!options.captureDensitySamples&&!bNeedsFarShell
                     &&!options.auditUniformBlockProofs)
                 {
                     out.diagnostics.meshingSkipped=true;
+                    if(options.hashDensity)
+                    {
+                        const FVoxelMeshData EmptyMesh;
+                        out.densityHash=14695981039346656037ull;
+                        out.meshHash=HashViewerMesh(EmptyMesh);
+                        out.payloadHash=HashPayload(EmptyMesh);
+                        out.topologyHash=HashTopology(EmptyMesh);
+                        out.materialHash=HashMaterialSamples(out.vertices);
+                        if(key.lod>=4)
+                        {
+                            out.meshHash=SaltFarHorizonHash(out.meshHash,options.farHorizonVersion);
+                            out.payloadHash=SaltFarHorizonHash(out.payloadHash,options.farHorizonVersion);
+                            out.topologyHash=SaltFarHorizonHash(out.topologyHash,options.farHorizonVersion);
+                        }
+                        out.hasDensityHash=out.hasMeshHash=out.hasPayloadHash=out.hasTopologyHash=true;
+                        out.hasMaterialHash=true;
+                    }
                     const auto Counts=FStandaloneShapeWorld::GetThreadClassificationStats();
                     const auto& Columns=VoxelForgeCore::Heightfield2D::threadColumnCacheStats();
                     out.diagnostics.solidBoxes=Counts.SolidBoxes;
@@ -2422,10 +2442,13 @@ namespace VoxelForgeCore
                     out.densitySampleCount=0;
                     return out;
                 }
-                // Native SurfaceWorld classifies each 8-cell block against its exact sample
-                // lattice. This lets the mesher avoid filling density grids for proven air/rock.
-                mesher.bUseBlockEarlyOut=true;
             }
+            // Keep sub-tile early-outs on native fields whose block interval is complete.
+            // The legacy compiled field has sparse tunnel/composer terms that can change a
+            // small block without making the current whole-tile bound fail; leave those blocks
+            // to the exact grid and use only the separately falsified whole-tile proof above.
+            if(bHasWorldAssembly&&step<=2&&bNativeSurfaceTile)
+                mesher.bUseBlockEarlyOut=true;
         }
         const auto MeshingStart=std::chrono::steady_clock::now();
         int32 MeshBandMinZVoxel=options.bandMinZVoxel;
@@ -2995,6 +3018,72 @@ namespace VoxelForgeCore
             const auto& values=options.captureDensitySamples?out.debugDensitySamples:densityValues;
             for(const float value:values)
             { densityHash^=std::bit_cast<std::uint32_t>(value);densityHash*=1099511628211ull; }
+
+            // A stream-hash run is the full-grid reference path. Record the exact sign
+            // uniformity ceiling from the same captured lattice that feeds Marching Cubes.
+            // Blocks are disjoint sample cubes; partial cubes at tile edges are included.
+            const std::size_t gridWidth=static_cast<std::size_t>(
+                std::clamp(MeshCells,2,CHUNK_SIZE)+3);
+            const std::size_t xySamples=gridWidth*gridWidth;
+            const std::size_t zSamples=xySamples>0&&values.size()%xySamples==0
+                ?values.size()/xySamples:0;
+            bool tileHasSign=false,tileUniform=true;
+            bool tileAir=false;
+            for(const float value:values)
+            {
+                if(!std::isfinite(value)||value==0.0f)
+                {tileUniform=false;continue;}
+                const bool air=value>0.0f;
+                if(!tileHasSign){tileHasSign=true;tileAir=air;}
+                else if(tileAir!=air)tileUniform=false;
+            }
+            const auto CountUniformBlocks=[&](std::size_t blockWidth)
+            {
+                std::uint64_t uniformBlocks=0,uniformSamples=0;
+                if(zSamples==0)return std::pair{uniformBlocks,uniformSamples};
+                for(std::size_t z0=0;z0<zSamples;z0+=blockWidth)
+                for(std::size_t y0=0;y0<gridWidth;y0+=blockWidth)
+                for(std::size_t x0=0;x0<gridWidth;x0+=blockWidth)
+                {
+                    const std::size_t z1=std::min(zSamples,z0+blockWidth);
+                    const std::size_t y1=std::min(gridWidth,y0+blockWidth);
+                    const std::size_t x1=std::min(gridWidth,x0+blockWidth);
+                    bool hasSign=false,uniform=true,air=false;
+                    for(std::size_t z=z0;z<z1&&uniform;++z)
+                    for(std::size_t y=y0;y<y1&&uniform;++y)
+                    for(std::size_t x=x0;x<x1;++x)
+                    {
+                        const float value=values[(z*gridWidth+y)*gridWidth+x];
+                        if(!std::isfinite(value)||value==0.0f)
+                        {uniform=false;break;}
+                        const bool sampleAir=value>0.0f;
+                        if(!hasSign){hasSign=true;air=sampleAir;}
+                        else if(air!=sampleAir){uniform=false;break;}
+                    }
+                    if(uniform&&hasSign)
+                    {
+                        ++uniformBlocks;
+                        uniformSamples+=static_cast<std::uint64_t>(z1-z0)
+                            *static_cast<std::uint64_t>(y1-y0)
+                            *static_cast<std::uint64_t>(x1-x0);
+                    }
+                }
+                return std::pair{uniformBlocks,uniformSamples};
+            };
+            const auto [uniformBlocks8,uniformSamples8]=CountUniformBlocks(8);
+            const auto [uniformBlocks4,uniformSamples4]=CountUniformBlocks(4);
+            const double centerZ=(static_cast<double>(origin.Z)
+                +static_cast<double>(extent)*0.5)*static_cast<double>(world.CoreVoxelSizeMicrons)
+                /10000.0;
+            const int32 stratum=world.Manager
+                ?world.Manager->GetStrateIndex(static_cast<float>(centerZ)):-1;
+            std::printf("[UniformGridCeiling] strate=%d lod=%d key=(%d,%d,%d) samples=%zu uniform=%d air=%d blocks8=%llu samples8=%llu blocks4=%llu samples4=%llu\n",
+                stratum,key.lod,key.coordinate.x,key.coordinate.y,key.coordinate.z,values.size(),
+                tileUniform&&tileHasSign?1:0,tileUniform&&tileHasSign&&tileAir?1:0,
+                static_cast<unsigned long long>(uniformBlocks8),
+                static_cast<unsigned long long>(uniformSamples8),
+                static_cast<unsigned long long>(uniformBlocks4),
+                static_cast<unsigned long long>(uniformSamples4));
             out.densityHash=densityHash;out.meshHash=HashViewerMesh(mesh);
             out.payloadHash=HashPayload(mesh);out.topologyHash=HashTopology(mesh);
             out.materialHash=HashMaterialSamples(out.vertices);