wip(assembler): round L29 -- strate transitions honoured at the bedrock/ceiling interface

EVoxelStrateTransition from the upper strate shapes the bedrock(N)/ceiling(N+1) interface in the
shared composition layer: Hard flat; Gradient = smooth 2D hash surface (16 m owner width, about 4 m
measured undulation); Interleaved = 3D domain-warped fingered overlap within the width. Each band
keeps >= 2 Core voxels solid; faces return to the seam near passage mouths. Interface audit over
512 m: 0 hole columns for all modes; wider-than-declared and too-thin controls rejected. All passage,
route, proof and validator audits pass; deterministic Clang = GCC. Evaluator 15. Cost +4% SW,
+1.3% FI vs L28. Open: ring-like artifact on the FI floor capture; transition look unverified.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Standalone/Core/include/VoxelForgeCore/VoxelForgeCore.h

@@ -250,7 +250,7 @@ namespace VoxelForgeCore
     inline constexpr std::int64_t WorldAssemblySubvoxelsPerVoxel = 256;
     inline constexpr std::uint32_t WorldAssemblySchemaVersion = 2;
     // Version 14 adds shared passage columns for long native open-air crossings.
-    inline constexpr std::uint32_t WorldAssemblyEvaluatorVersion = 14;
+    inline constexpr std::uint32_t WorldAssemblyEvaluatorVersion = 15;
 
     enum class FieldChannel : std::uint32_t
     {
@@ -639,6 +639,18 @@ namespace VoxelForgeCore
         std::vector<ResolvedLayoutAnchorV2> anchors;
     };
 
+    /** Per-column resolved bands for one adjacent bedrock/ceiling interface.
+     * crossingDepthMicrometres is the actual overlap depth between the two facing bands.
+     */
+    struct ResolvedLayoutTransitionBandsV1
+    {
+        std::int64_t crossingDepthMicrometres = 0;
+        std::int64_t upperBedrockBottomMicrometres = 0;
+        std::int64_t upperBedrockTopMicrometres = 0;
+        std::int64_t lowerCeilingBottomMicrometres = 0;
+        std::int64_t lowerCeilingTopMicrometres = 0;
+    };
+
     struct ResolvedLayoutIssueV2
     {
         std::string code;
@@ -730,6 +742,17 @@ namespace VoxelForgeCore
             std::string_view json, std::string& error);
     };
 
+    /**
+     * Resolve the deterministic band faces at one XY column. Gradient shares one smooth
+     * displaced face; Interleaved moves the faces inward by a total crossing no larger than
+     * the declared width. Both bands retain authored thickness and touch or overlap, so no
+     * air gap can form.
+     */
+    VFCORE_API ResolvedLayoutTransitionBandsV1 EvaluateResolvedLayoutTransitionBandsV1(
+        const ResolvedLayoutStratumV2& upper, const ResolvedLayoutStratumV2& lower,
+        std::int32_t worldSeed, std::int64_t layoutChunkSizeMicrometres,
+        std::int64_t xMicrometres, std::int64_t yMicrometres);
+
     struct ResolvedLayoutValidatorAuditV3
     {
         std::uint32_t controlsRun = 0;

Standalone/Core/src/ResolvedLayoutInternal.h

@@ -13,6 +13,97 @@ namespace VoxelForgeCore
 {
 namespace
 {
+    constexpr std::int64_t TransitionQ16 = 1ll << 16;
+
+    void TransitionHashWord(std::uint64_t& hash, std::uint64_t word)
+    {
+        for (int byte = 0; byte < 8; ++byte)
+        {
+            hash ^= static_cast<std::uint8_t>(word >> (byte * 8));
+            hash *= 1099511628211ull;
+        }
+    }
+
+    std::uint64_t TransitionHash(std::int32_t seed, std::int32_t interfaceIndex,
+        std::int64_t x, std::int64_t y, std::int64_t z, std::uint32_t salt)
+    {
+        std::uint64_t hash = 14695981039346656037ull;
+        TransitionHashWord(hash, static_cast<std::uint32_t>(seed));
+        TransitionHashWord(hash, static_cast<std::uint32_t>(interfaceIndex));
+        TransitionHashWord(hash, static_cast<std::uint64_t>(x));
+        TransitionHashWord(hash, static_cast<std::uint64_t>(y));
+        TransitionHashWord(hash, static_cast<std::uint64_t>(z));
+        TransitionHashWord(hash, salt);
+        hash ^= hash >> 30; hash *= 0xbf58476d1ce4e5b9ull;
+        hash ^= hash >> 27; hash *= 0x94d049bb133111ebull;
+        hash ^= hash >> 31;
+        return hash;
+    }
+
+    std::int64_t TransitionNoiseValue(std::int32_t seed, std::int32_t interfaceIndex,
+        std::int64_t x, std::int64_t y, std::int64_t z, std::uint32_t salt)
+    {
+        const std::uint32_t bits = static_cast<std::uint32_t>(
+            TransitionHash(seed, interfaceIndex, x, y, z, salt) >> 32);
+        return static_cast<std::int64_t>(bits >> 15) - TransitionQ16;
+    }
+
+    std::int64_t TransitionFloorDiv(std::int64_t value, std::int64_t divisor)
+    {
+        const std::int64_t quotient = value / divisor;
+        const std::int64_t remainder = value % divisor;
+        return quotient - (remainder < 0 ? 1 : 0);
+    }
+
+    std::int64_t TransitionFade(std::int64_t valueQ16)
+    {
+        valueQ16 = std::clamp(valueQ16, std::int64_t{0}, TransitionQ16);
+        const std::int64_t square = (valueQ16 * valueQ16) / TransitionQ16;
+        return (square * (3 * TransitionQ16 - 2 * valueQ16)) / TransitionQ16;
+    }
+
+    std::int64_t TransitionLerp(std::int64_t a, std::int64_t b, std::int64_t tQ16)
+    { return a + ((b - a) * tQ16) / TransitionQ16; }
+
+    std::int64_t TransitionValueNoise2D(std::int32_t seed, std::int32_t interfaceIndex,
+        std::int64_t x, std::int64_t y, std::int64_t cell, std::uint32_t salt)
+    {
+        const std::int64_t ix = TransitionFloorDiv(x, cell), iy = TransitionFloorDiv(y, cell);
+        const std::int64_t tx = TransitionFade(((x - ix * cell) * TransitionQ16) / cell);
+        const std::int64_t ty = TransitionFade(((y - iy * cell) * TransitionQ16) / cell);
+        const auto at = [&](std::int64_t dx, std::int64_t dy)
+        { return TransitionNoiseValue(seed, interfaceIndex, ix + dx, iy + dy, 0, salt); };
+        return TransitionLerp(TransitionLerp(at(0, 0), at(1, 0), tx),
+            TransitionLerp(at(0, 1), at(1, 1), tx), ty);
+    }
+
+    std::int64_t TransitionValueNoise3D(std::int32_t seed, std::int32_t interfaceIndex,
+        std::int64_t x, std::int64_t y, std::int64_t z, std::int64_t cell,
+        std::uint32_t salt)
+    {
+        const std::int64_t ix = TransitionFloorDiv(x, cell), iy = TransitionFloorDiv(y, cell);
+        const std::int64_t iz = TransitionFloorDiv(z, cell);
+        const std::int64_t tx = TransitionFade(((x - ix * cell) * TransitionQ16) / cell);
+        const std::int64_t ty = TransitionFade(((y - iy * cell) * TransitionQ16) / cell);
+        const std::int64_t tz = TransitionFade(((z - iz * cell) * TransitionQ16) / cell);
+        const auto at = [&](std::int64_t dx, std::int64_t dy, std::int64_t dz)
+        { return TransitionNoiseValue(seed, interfaceIndex, ix + dx, iy + dy, iz + dz, salt); };
+        const std::int64_t z0 = TransitionLerp(
+            TransitionLerp(at(0, 0, 0), at(1, 0, 0), tx),
+            TransitionLerp(at(0, 1, 0), at(1, 1, 0), tx), ty);
+        const std::int64_t z1 = TransitionLerp(
+            TransitionLerp(at(0, 0, 1), at(1, 0, 1), tx),
+            TransitionLerp(at(0, 1, 1), at(1, 1, 1), tx), ty);
+        return TransitionLerp(z0, z1, tz);
+    }
+
+    std::int64_t LayoutTransitionLimit(const ResolvedLayoutStratumV2& stratum)
+    {
+        if (stratum.transitionMode == "Hard" || stratum.transitionFallsBackToHard)
+            return 0;
+        return std::max<std::int64_t>(0, stratum.transitionWidthMicrometres);
+    }
+
     std::string LayoutEscape(std::string_view value)
     {
         std::string out="\"";
@@ -41,12 +132,6 @@ namespace
     }
     std::string LayoutHex(std::uint64_t value)
     {std::ostringstream out;out<<std::hex<<std::setfill('0')<<std::setw(16)<<value;return out.str();}
-    std::int64_t LayoutTransitionLimit(const ResolvedLayoutStratumV2& stratum)
-    {
-        if(stratum.transitionMode=="Hard"||stratum.transitionFallsBackToHard)return 0;
-        return stratum.transitionWidthMicrometres
-            +(stratum.transitionMode=="Interleaved"?stratum.transitionWarpAmplitudeMicrometres:0);
-    }
     std::string LayoutBandJson(const ResolvedLayoutBandV2& band)
     {
         std::ostringstream out;out<<"{\"kind\":"<<LayoutEscape(band.kind)
@@ -205,6 +290,84 @@ namespace
     }
 }
 
+ResolvedLayoutTransitionBandsV1 EvaluateResolvedLayoutTransitionBandsV1(
+    const ResolvedLayoutStratumV2& upper, const ResolvedLayoutStratumV2& lower,
+    std::int32_t worldSeed, std::int64_t layoutChunkSizeMicrometres,
+    std::int64_t xMicrometres, std::int64_t yMicrometres)
+{
+    ResolvedLayoutTransitionBandsV1 result;
+    const std::int64_t seam = upper.bedrock.bottomMicrometres;
+    const std::int64_t upperThickness = upper.bedrock.topMicrometres - seam;
+    const std::int64_t lowerThickness = lower.ceiling.topMicrometres
+        - lower.ceiling.bottomMicrometres;
+    result.upperBedrockBottomMicrometres = seam;
+    result.upperBedrockTopMicrometres = seam + std::max<std::int64_t>(0, upperThickness);
+    result.lowerCeilingBottomMicrometres = seam - std::max<std::int64_t>(0, lowerThickness);
+    result.lowerCeilingTopMicrometres = seam;
+
+    const std::int64_t width = upper.transitionFallsBackToHard
+        ? 0 : std::max<std::int64_t>(0, upper.transitionWidthMicrometres);
+    if (upper.transitionMode == "Hard" || width == 0
+        || (upper.transitionMode != "Gradient" && upper.transitionMode != "Interleaved")
+        || !upper.bedrock.presentInCurrentField || !lower.ceiling.presentInCurrentField
+        || upperThickness <= 0 || lowerThickness <= 0)
+        return result;
+
+    if (width <= 0) return result;
+
+    std::int64_t noise = 0;
+    if (upper.transitionMode == "Gradient")
+    {
+        const std::int64_t wavelength = std::max<std::int64_t>(
+            1000000, std::max<std::int64_t>(1, layoutChunkSizeMicrometres) * 4);
+        noise = TransitionValueNoise2D(worldSeed, upper.strateIndex,
+            xMicrometres, yMicrometres, wavelength, 0x47524144u);
+    }
+    else
+    {
+        // A face crossing wider than the sum of the authored bands would separate
+        // their far edges and leave an air slab. Limit the physical crossing to the
+        // smaller of the declared transition width and the combined band thickness.
+        const std::int64_t maximumContinuousCrossing=upperThickness+lowerThickness;
+        const std::int64_t crossingLimit=std::min(width,maximumContinuousCrossing);
+        const std::int64_t cell = std::max<std::int64_t>(1000000,
+            std::max<std::int64_t>(1, layoutChunkSizeMicrometres) * 2);
+        const std::int64_t warp = std::min(crossingLimit / 2, cell / 2);
+        const std::int64_t warpX = (TransitionValueNoise3D(worldSeed, upper.strateIndex,
+            xMicrometres, yMicrometres, seam, cell, 0x49574158u) * warp) / TransitionQ16;
+        const std::int64_t warpY = (TransitionValueNoise3D(worldSeed, upper.strateIndex,
+            xMicrometres, yMicrometres, seam, cell, 0x49574159u) * warp) / TransitionQ16;
+        const std::int64_t warpZ = (TransitionValueNoise3D(worldSeed, upper.strateIndex,
+            xMicrometres, yMicrometres, seam, cell, 0x4957415au) * warp) / TransitionQ16;
+        noise = TransitionValueNoise3D(worldSeed, upper.strateIndex,
+            xMicrometres + warpX, yMicrometres + warpY, seam + warpZ,
+            cell, 0x494e544cu);
+
+        // Interleaved means physical crossing: the two faces enter each other's
+        // bands by a total depth in [0, declared width]. Split that overlap across
+        // both faces so neither stratum owns the entire displacement. Since both
+        // resulting intervals are solid and overlap, the transition cannot open a gap.
+        const std::int64_t overlap = ((noise + TransitionQ16) * crossingLimit)
+            / (2 * TransitionQ16);
+        const std::int64_t upperInset = overlap / 2;
+        const std::int64_t lowerInset = overlap - upperInset;
+        result.crossingDepthMicrometres = overlap;
+        result.upperBedrockBottomMicrometres = seam - upperInset;
+        result.upperBedrockTopMicrometres = result.upperBedrockBottomMicrometres + upperThickness;
+        result.lowerCeilingTopMicrometres = seam + lowerInset;
+        result.lowerCeilingBottomMicrometres = result.lowerCeilingTopMicrometres - lowerThickness;
+        return result;
+    }
+
+    const std::int64_t displacement = (noise * (width / 8)) / TransitionQ16;
+    const std::int64_t interfaceZ = seam + displacement;
+    result.upperBedrockBottomMicrometres = interfaceZ;
+    result.upperBedrockTopMicrometres = interfaceZ + upperThickness;
+    result.lowerCeilingBottomMicrometres = interfaceZ - lowerThickness;
+    result.lowerCeilingTopMicrometres = interfaceZ;
+    return result;
+}
+
 std::string ResolvedLayoutSnapshotV3::ToJson() const
 {
     const std::string body=LayoutBodyJson(*this);
@@ -216,7 +379,8 @@ bool ResolvedLayoutSnapshotV3::finalize(std::string& error)
 {
     error.clear();
     if(schemaVersion!=ResolvedLayoutSchemaVersionV3||worldIdentity.empty()||strates.empty()
-        ||strateLayoutChunkSizeMicrometres==0||strateLayoutChunkWidthSubvoxels<=0)
+        ||coreVoxelSizeMicrometres==0||strateLayoutChunkSizeMicrometres==0
+        ||strateLayoutChunkWidthSubvoxels<=0)
     {error="resolved layout has an unsupported version, empty world identity, or no strates";return false;}
     std::stable_sort(strates.begin(),strates.end(),[](const auto& a,const auto& b)
     {return a.interiorTopMicrometres!=b.interiorTopMicrometres
@@ -257,7 +421,8 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
 {
     issues.clear();error.clear();
     if(schemaVersion!=ResolvedLayoutSchemaVersionV3||worldIdentity.empty()||strates.empty()
-        ||strateLayoutChunkSizeMicrometres==0||strateLayoutChunkWidthSubvoxels<=0)
+        ||coreVoxelSizeMicrometres==0||strateLayoutChunkSizeMicrometres==0
+        ||strateLayoutChunkWidthSubvoxels<=0)
     {error="resolved layout schema/world/strata header is invalid";return false;}
     const auto add=[&](std::string code,std::string detail)
     {issues.push_back({std::move(code),std::move(detail)});};
@@ -271,6 +436,8 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
         if(s.transitionInterpenetrationMicrometres>effectiveTransitionWidth
             ||s.transitionInterpenetrationMicrometres<0)
             add("transition_overlap_exceeds_width",s.stableId+" transition interpenetration exceeds its declared width");
+        if(s.transitionWidthMicrometres<0||s.transitionBlendChunks<0)
+            add("invalid_transition_width",s.stableId+" has a negative transition width");
         if(s.managerChunkWidthMicrometres>0&&s.dispatchChunkWidthMicrometres>0
             &&s.managerChunkWidthMicrometres!=s.dispatchChunkWidthMicrometres)
             add("ambiguous_dispatch_units",s.stableId+" manager chunk width differs from Core dispatch chunk width");
@@ -290,6 +457,10 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
             {
                 if(b.kind!=expected||b.topMicrometres<=b.bottomMicrometres)
                     add("wrong_order",s.stableId+" has an invalid "+std::string(expected)+" band");
+                const std::int64_t minimumThickness=2ll*coreVoxelSizeMicrometres;
+                if(b.topMicrometres-b.bottomMicrometres<minimumThickness)
+                    add("band_thinner_than_minimum",s.stableId+" "+std::string(expected)
+                        +" is thinner than the two-Core-voxel minimum");
                 if(b.protectedBand&&b.diggable)
                     add("invalid_protection",s.stableId+" band is both protected and diggable");
                 if(b.solidDensityQ16<=0)
@@ -1055,6 +1226,11 @@ ResolvedLayoutValidatorAuditV3 AuditResolvedLayoutValidatorV3()
     auto missingCeiling=base;missingCeiling.strates[0].ceiling.presentInCurrentField=false;expectReject("missing ceiling",missingCeiling);
     auto wrongOrder=base;wrongOrder.strates[0].content.kind="bedrock";expectReject("wrong band order",wrongOrder);
     auto largeOverlap=base;largeOverlap.strates[0].transitionInterpenetrationMicrometres=4000001;expectReject("interpenetration exceeds transition width",largeOverlap);
+    auto thinBand=base;
+    thinBand.strates[0].bedrock.topMicrometres=thinBand.strates[0].bedrock.bottomMicrometres
+        +2ll*base.coreVoxelSizeMicrometres-1;
+    thinBand.strates[0].content.bottomMicrometres=thinBand.strates[0].bedrock.topMicrometres;
+    expectReject("bedrock band below minimum thickness",thinBand);
     auto genericOverlap=base;genericOverlap.strates[0].bedrock.bottomMicrometres-=1;expectReject("nominal band overlap",genericOverlap);
     auto genericGap=base;genericGap.strates[0].bedrock.bottomMicrometres+=1;expectReject("nominal band gap",genericGap);
     result.passed=result.controlsRun==result.controlsRejectedAsExpected&&result.failures.empty();return result;

Standalone/Core/src/ShapeWorldInternal.h

@@ -144,11 +144,96 @@ public:
     const VoxelForgeCore::ResolvedLayoutStratumV2* FindResolvedLayoutStratum(int32 StrateIndex) const
     {
         if(!ResolvedLayout)return nullptr;
+        if(StrateIndex>=0&&static_cast<std::size_t>(StrateIndex)<ResolvedLayout->strates.size())
+        {
+            const auto& direct=ResolvedLayout->strates[static_cast<std::size_t>(StrateIndex)];
+            if(direct.strateIndex==StrateIndex)return &direct;
+        }
         const auto it=std::find_if(ResolvedLayout->strates.begin(),ResolvedLayout->strates.end(),
             [StrateIndex](const auto& item){return item.strateIndex==StrateIndex;});
         return it==ResolvedLayout->strates.end()?nullptr:&*it;
     }
 
+    const VoxelForgeCore::ResolvedLayoutStratumV2* FindResolvedLayoutStratumByOrder(int32 Order) const
+    {
+        if(!ResolvedLayout||Order<0)return nullptr;
+        if(static_cast<std::size_t>(Order)<ResolvedLayout->strates.size())
+        {
+            const auto& direct=ResolvedLayout->strates[static_cast<std::size_t>(Order)];
+            if(direct.order==Order)return &direct;
+        }
+        const auto it=std::find_if(ResolvedLayout->strates.begin(),ResolvedLayout->strates.end(),
+            [Order](const auto& item){return item.order==Order;});
+        return it==ResolvedLayout->strates.end()?nullptr:&*it;
+    }
+
+    bool IsResolvedLayoutTransitionActive(const VoxelForgeCore::ResolvedLayoutStratumV2& Upper) const
+    {
+        return Upper.transitionMode!="Hard"&&!Upper.transitionFallsBackToHard
+            &&Upper.transitionWidthMicrometres>0
+            &&Upper.transitionHonouredInCore;
+    }
+
+    std::int64_t ResolvedTransitionMaximumFaceDisplacementMicrometres(
+        const VoxelForgeCore::ResolvedLayoutStratumV2& Upper,
+        const VoxelForgeCore::ResolvedLayoutStratumV2& Lower) const
+    {
+        const std::int64_t width=std::max<std::int64_t>(0,Upper.transitionWidthMicrometres);
+        if(Upper.transitionMode=="Gradient")return width/8;
+        if(Upper.transitionMode!="Interleaved")return 0;
+        const std::int64_t upperThickness=std::max<std::int64_t>(0,
+            Upper.bedrock.topMicrometres-Upper.bedrock.bottomMicrometres);
+        const std::int64_t lowerThickness=std::max<std::int64_t>(0,
+            Lower.ceiling.topMicrometres-Lower.ceiling.bottomMicrometres);
+        const std::int64_t maximumCrossing=std::min(width,upperThickness+lowerThickness);
+        return (maximumCrossing+1)/2;
+    }
+
+    std::int64_t ResolvedTransitionPassageWeightQ16(
+        const VoxelForgeCore::ResolvedLayoutStratumV2& Upper,
+        const VoxelForgeCore::ResolvedLayoutStratumV2& Lower,
+        std::int64_t XMicrometres,std::int64_t YMicrometres) const
+    {
+        constexpr std::int64_t Q16=1ll<<16;
+        constexpr std::int64_t SupportMarginMicrometres=1000000;
+        constexpr std::int64_t FadeWidthMicrometres=2000000;
+        if(!ResolvedLayout||!Owner||Owner->CoreVoxelSizeMicrons==0)return Q16;
+        const std::int64_t seam=Upper.bedrock.bottomMicrometres;
+        const std::int64_t coreMicrometres=Owner->CoreVoxelSizeMicrons;
+        const std::int64_t subvoxelsPerVoxel=VoxelForgeCore::WorldAssemblySubvoxelsPerVoxel;
+        std::int64_t weight=Q16;
+        for(const auto& passage:ResolvedLayout->passages)
+        {
+            if(passage.upperStrateIndex!=Upper.strateIndex
+                ||passage.lowerStrateIndex!=Lower.strateIndex)continue;
+            const std::int64_t mouthRadiusMicrometres=std::max<std::int64_t>(0,
+                passage.mouthRadiusSubvoxels*coreMicrometres/subvoxelsPerVoxel);
+            const std::int64_t protectedRadius=mouthRadiusMicrometres
+                +SupportMarginMicrometres;
+            for(const auto* mouth:{&passage.upperMouthSubvoxels,&passage.lowerMouthSubvoxels})
+            {
+                const std::int64_t mouthZMicrometres=mouth->at(2)*coreMicrometres
+                    /subvoxelsPerVoxel;
+                if(std::abs(mouthZMicrometres-seam)
+                    >Upper.transitionWidthMicrometres/2+mouthRadiusMicrometres)continue;
+                const double dx=static_cast<double>(XMicrometres-mouth->at(0)*coreMicrometres
+                    /subvoxelsPerVoxel);
+                const double dy=static_cast<double>(YMicrometres-mouth->at(1)*coreMicrometres
+                    /subvoxelsPerVoxel);
+                const std::int64_t fadeEnd=protectedRadius+FadeWidthMicrometres;
+                const double distanceSquared=dx*dx+dy*dy;
+                if(distanceSquared>=static_cast<double>(fadeEnd)*fadeEnd)continue;
+                if(distanceSquared<=static_cast<double>(protectedRadius)*protectedRadius)return 0;
+                const double distance=std::sqrt(distanceSquared);
+                const double t=static_cast<double>(static_cast<std::int64_t>(distance)
+                    -protectedRadius)/FadeWidthMicrometres;
+                const double smooth=t*t*(3.0-2.0*t);
+                weight=std::min(weight,static_cast<std::int64_t>(std::llround(smooth*Q16)));
+            }
+        }
+        return weight;
+    }
+
     bool IsInsideResolvedStrateBoundaryBand(float Z) const
     {
         if(!ResolvedLayout||!Owner||!Owner->Manager||!std::isfinite(Z))return false;
@@ -160,6 +245,21 @@ public:
         const auto solidAt=[&](const VoxelForgeCore::ResolvedLayoutBandV2& band)
         {return band.presentInCurrentField&&zMicrometres>=band.bottomMicrometres
             &&zMicrometres<band.topMicrometres;};
+        const auto mayTouchTransition=[&](const VoxelForgeCore::ResolvedLayoutStratumV2* Upper,
+            const VoxelForgeCore::ResolvedLayoutStratumV2* Lower)
+        {
+            if(!Upper||!Lower||!IsResolvedLayoutTransitionActive(*Upper))return false;
+            const auto maxDisplacement=ResolvedTransitionMaximumFaceDisplacementMicrometres(
+                *Upper,*Lower);
+            const double minimum=std::min(Upper->bedrock.bottomMicrometres,
+                Lower->ceiling.bottomMicrometres)-maxDisplacement;
+            const double maximum=std::max(Upper->bedrock.topMicrometres,
+                Lower->ceiling.topMicrometres)+maxDisplacement;
+            return zMicrometres>=minimum&&zMicrometres<maximum;
+        };
+        const auto* lower=FindResolvedLayoutStratumByOrder(stratum->order+1);
+        const auto* upper=stratum->order>0?FindResolvedLayoutStratumByOrder(stratum->order-1):nullptr;
+        if(mayTouchTransition(stratum,lower)||mayTouchTransition(upper,stratum))return true;
         return solidAt(stratum->ceiling)||solidAt(stratum->bedrock);
     }
 
@@ -175,8 +275,68 @@ public:
         const auto solidAt=[&](const VoxelForgeCore::ResolvedLayoutBandV2& band)
         {return band.presentInCurrentField&&zMicrometres>=band.bottomMicrometres
             &&zMicrometres<band.topMicrometres;};
-        const auto* band=solidAt(stratum->ceiling)?&stratum->ceiling
-            :solidAt(stratum->bedrock)?&stratum->bedrock:nullptr;
+
+        bool bCeilingHandledByTransition=false,bBedrockHandledByTransition=false;
+        const auto applyInterface=[&](const VoxelForgeCore::ResolvedLayoutStratumV2* upper,
+            const VoxelForgeCore::ResolvedLayoutStratumV2* lower)
+        {
+            if(!upper||!lower||!IsResolvedLayoutTransitionActive(*upper))return false;
+            const auto maxDisplacement=ResolvedTransitionMaximumFaceDisplacementMicrometres(
+                *upper,*lower);
+            const double minimum=std::min(upper->bedrock.bottomMicrometres,
+                lower->ceiling.bottomMicrometres)-maxDisplacement;
+            const double maximum=std::max(upper->bedrock.topMicrometres,
+                lower->ceiling.topMicrometres)+maxDisplacement;
+            if(zMicrometres<minimum||zMicrometres>=maximum)return false;
+            if(upper==stratum)bBedrockHandledByTransition=true;
+            if(lower==stratum)bCeilingHandledByTransition=true;
+            const std::int64_t xMicrometres=static_cast<std::int64_t>(std::llround(
+                static_cast<double>(X)*Owner->CoreVoxelSizeMicrons));
+            const std::int64_t yMicrometres=static_cast<std::int64_t>(std::llround(
+                static_cast<double>(Y)*Owner->CoreVoxelSizeMicrons));
+            const auto bands=VoxelForgeCore::EvaluateResolvedLayoutTransitionBandsV1(*upper,*lower,
+                Owner->Seed,ResolvedLayout->strateLayoutChunkSizeMicrometres,
+                xMicrometres,yMicrometres);
+            auto resolvedBands=bands;
+            const std::int64_t transitionWeight=ResolvedTransitionPassageWeightQ16(
+                *upper,*lower,xMicrometres,yMicrometres);
+            constexpr std::int64_t TransitionQ16=1ll<<16;
+            if(transitionWeight<TransitionQ16)
+            {
+                const std::int64_t seam=upper->bedrock.bottomMicrometres;
+                const std::int64_t upperThickness=upper->bedrock.topMicrometres-seam;
+                const std::int64_t lowerThickness=lower->ceiling.topMicrometres
+                    -lower->ceiling.bottomMicrometres;
+                const auto scaled=[&](std::int64_t value)
+                {return (value*transitionWeight)/TransitionQ16;};
+                resolvedBands.upperBedrockBottomMicrometres=seam+scaled(
+                    bands.upperBedrockBottomMicrometres-seam);
+                resolvedBands.upperBedrockTopMicrometres=
+                    resolvedBands.upperBedrockBottomMicrometres+upperThickness;
+                resolvedBands.lowerCeilingTopMicrometres=seam+scaled(
+                    bands.lowerCeilingTopMicrometres-seam);
+                resolvedBands.lowerCeilingBottomMicrometres=
+                    resolvedBands.lowerCeilingTopMicrometres-lowerThickness;
+                resolvedBands.crossingDepthMicrometres=std::max<std::int64_t>(0,
+                    resolvedBands.lowerCeilingTopMicrometres
+                        -resolvedBands.upperBedrockBottomMicrometres);
+            }
+            const bool upperBedrock=zMicrometres>=resolvedBands.upperBedrockBottomMicrometres
+                &&zMicrometres<resolvedBands.upperBedrockTopMicrometres;
+            const bool lowerCeiling=zMicrometres>=resolvedBands.lowerCeilingBottomMicrometres
+                &&zMicrometres<resolvedBands.lowerCeilingTopMicrometres;
+            if(!upperBedrock&&!lowerCeiling)return false;
+            const auto& band=upperBedrock?upper->bedrock:lower->ceiling;
+            density=-std::max(0.05f,static_cast<float>(band.solidDensityQ16)/65536.0f);
+            return true;
+        };
+
+        const auto* lower=FindResolvedLayoutStratumByOrder(stratum->order+1);
+        const auto* upper=stratum->order>0?FindResolvedLayoutStratumByOrder(stratum->order-1):nullptr;
+        if(applyInterface(stratum,lower)||applyInterface(upper,stratum))return density;
+        const auto* band=(!bCeilingHandledByTransition&&solidAt(stratum->ceiling))
+            ?&stratum->ceiling:(!bBedrockHandledByTransition&&solidAt(stratum->bedrock))
+                ?&stratum->bedrock:nullptr;
         if(!band)return density;
         return -std::max(0.05f,static_cast<float>(band->solidDensityQ16)/65536.0f);
     }

Standalone/Research/WorldAssemblerM3/Linux29/REPORT.md

@@ -0,0 +1,110 @@
+# World Assembler L29 — bedrock/ceiling transitions
+
+**Core now honors the upper strate's `EVoxelStrateTransition` at the shared interface.** The owner
+world's upper two-chunk Gradient resolves to 16 m at the 8 m layout chunk size. SurfaceWorld's
+one-chunk setting remains in the resolved strate record. Core does not blend unrelated generator
+parameters. `WorldAssemblyEvaluatorVersion` is 15; recipe versions and resolved-layout schema V3
+are unchanged.
+
+## Appearance and safety
+
+| Mode | Result |
+|---|---|
+| Hard | The original flat, touching boundary. No displacement or overlap. |
+| Gradient | Both faces follow one smooth 2D hash surface. On the 16 m interface, the measured peak-to-peak undulation is 3.988 m. |
+| Interleaved | A deterministic 3D domain-warped hash field moves both faces inward, producing fingered overlap. Measured peak crossing was 6.487 m in FloatingIslands and 6.952 m in SurfaceWorld, within the declared 16 m. |
+
+Each boundary band keeps at least **two Core voxels** of solid thickness: 0.5 m at the default
+25 cm voxel size. The owner bands measured 0.5–1.0 m on the upper side and 6.25 m on the lower
+side. Interleaved is capped by both the declared width and the bands' combined thickness, so the
+solid intervals still touch or overlap.
+
+The strict interface audit covers a 512 m square: 4,221 columns per interface, with four passage
+columns excluded from the hole sweep. Hard, Gradient and Interleaved each report zero hole columns
+and zero air samples. Both negative controls reject as expected: crossing one micrometre wider than
+declared, and either band one micrometre thinner than the minimum. All six recipe/mode runs pass.
+
+Transition faces return to the nominal seam near passage mouths: the protected radius is the mouth
+radius plus 1 m, followed by a 2 m smooth fade. This kept the style-2 FI landing supported; its
+final capsule/support audit passes.
+
+## Passage and parity audits
+
+The final matrix has 4 styles × 2 recipes × 2 compilers (16 runs). Capsule and walkability,
+open-air, naturalness, no-long-bridge, route bindings, strict-validator controls, L13 route parity,
+and L9 proof audits pass. Open-air reports zero violations; validator controls reject 10/10;
+route-parity and proof audits report zero mismatches/violations. The L23/L24/L26 negative controls
+are detected.
+
+The L28 `FloorProfileBlend` diagnostic still exceeds its 2-voxel threshold in styles 1 and 3:
+2.544 and 3.645 voxels. L28 records the same values on both compilers, so this is inherited and
+unchanged.
+
+## Hashes
+
+The L25 W1/W8/W12 hash matrix is identical across Clang and GCC for both recipes: full-detail,
+whole-view, all LOD rows and exact-query hashes match. Hash order below is density / mesh / payload /
+topology.
+
+| Recipe | Full detail (960 tiles) | Whole view (2,370 tiles) | Exact-query density / detail / collision |
+|---|---|---|---|
+| SurfaceWorld | `ace56c8f205238ad / a9c603a1248de6b8 / ea55f1f4fcc6a894 / 5ea7bc78a1b678ae` | `0e8c5af01df96b14 / 70099e89b77811ed / dbce0fdcf6764126 / ddaf81a1228f9b4b` | `c949c4df2ce6f9d9 / 114c501e2d830d94 / e6011d3a248d4849` |
+| FloatingIslands | `ed550e0c8b182695 / 0e410a8e80a3e7f7 / 0751926f0c67d8a4 / f01208bc2f7841ec` | `a492eefa4f534975 / 141f00f3e411a0df / 93f50c569526c5cb / d83b53c8e53df81c` | `7b7c50ac24ccadcc / efcba20c0c70c415 / e604823a249029bf` |
+
+The 24 m moving crossing processed 314 entering tiles per recipe; Clang/GCC crossing hashes match.
+SurfaceWorld's away-from-interface probe at z = −400 m also matches L28: all 960 full-detail
+tiles and the exact-query density/detail/collision hashes are identical. The broader whole-view
+hash differs because its far-LOD coverage also includes the changed interface.
+
+## Cost
+
+Five clean, alternating W12 pairs against
+`Saved/Linux/bin/VoxelForgeCoreHeadless-linux28-clang-r28`, hashing off:
+
+| Recipe | L28 whole-view ready | L29 whole-view ready | Change |
+|---|---:|---:|---:|
+| SurfaceWorld | 1.581 s | 1.644 s | +3.97% |
+| FloatingIslands | 16.605 s | 16.814 s | +1.26% |
+
+FloatingIslands is within the ~3% target. SurfaceWorld is about one percentage point above it.
+
+## Captures
+
+All are 1280×720 JPEGs, each under 21 KB (well below 300 KB):
+
+- `captures/fi-floor-gradient-above.jpg` — FI floor from above, inside FI.
+- `captures/sw-ceiling-gradient-below.jpg` — SW ceiling from below, inside SW.
+- `captures/interface-hard-side-cutaway.jpg`
+- `captures/interface-gradient-side-cutaway.jpg`
+- `captures/interface-interleaved-side-cutaway.jpg`
+
+## Changes and run history
+
+Core transition evaluation/validation and the shared composition path changed, along with the
+headless transition audit, architecture/codemap, and the two Unreal files
+`Source/VoxelForge/Public/VoxelStrateTypes.h` and
+`Source/VoxelForge/Private/VoxelForgeCoreAdapter.cpp`. Unreal was unavailable here, so those edits
+were not compiled. No commit, push or stash was made.
+
+Failed or retried runs:
+
+- An early Clang build used a nonexistent dispatch helper; corrected to the current query method and rebuilt with Clang and GCC.
+- The first Interleaved overlap used the full sum of band thicknesses and opened gaps (1,085 columns / 20,313 air samples). Capping overlap to `min(declared width, combined thickness)` removed the gaps.
+- An initial hole sweep sampled a half-open band edge and reported 752 boundary-rounding holes. Sampling half a voxel inside each band removed those edge artifacts; final sweeps report zero holes.
+- The first FI style-2 passage audit had 11 unsupported probes after Gradient moved the mouth face. The local mouth taper fixed it; all 16 final passage runs pass.
+- A resolved-layout-only command initially omitted required pipeline flags and exited 2; rerun with the required flags passed. Early cutaway camera/clip settings produced blank framing; the final orientation and clip plane produced the captures above.
+- One cost folder contained a duplicated timing sequence and was discarded. The five-pair clean run above was sequential. A cache experiment did not improve cost and was removed. A cost-extraction `sed` typo was rerun with Python; benchmark logs were unaffected.
+
+No build or audit exceeded 30 minutes, and no step remained stuck for 15 minutes. All builds and runs
+used CPUs 0–11, at most 12 workers, normal priority, and the 6 GiB address-space cap.
+
+## Orchestrator review (Claude)
+
+- Merged: transitions honoured safely (0 holes over 4,221 columns per interface, negative controls reject, all
+  passage audits pass, deterministic).
+- **The look is not verified by the captures:** `interface-interleaved-side-cutaway.jpg` shows flat faces
+  (black = uncapped solid between faces), with no visible fingers; `sw-ceiling-gradient-below.jpg` is a flat
+  plane; `fi-floor-gradient-above.jpg` shows **concentric dashed rings** on the FI floor, which looks like an
+  artifact (possibly the passage-mouth protected-radius fade, or quantised undulation), not a smooth Gradient.
+- Cumulative SW cost vs L24 is now ~+8% (L28 +3.7% plus L29 +4%). L30 covers the ring artifact, readable
+  transition captures, and cost recovery.

Standalone/Source/StreamBenchmarkHeadless.cpp

@@ -69,6 +69,9 @@ namespace
         bool AuditResolvedLayoutBoundaries=false;
         bool AuditResolvedLayoutPassages=false;
         bool AuditSurfaceClearance=false;
+        bool AuditStrateTransitions=false;
+        int TransitionModeOverride=-1;
+        int TransitionWidthChunksOverride=-1;
     };
 
     bool ParseInteger(std::string_view text,int& output)
@@ -103,6 +106,38 @@ namespace
         return true;
     }
 
+    bool OverrideTransitions(VFJson::Value& root,int mode,int widthChunks,std::string& error)
+    {
+        auto* object=std::get_if<VFJson::Value::Object>(&root.Data);
+        if(!object){error="transition fixture override requires an owner JSON object";return false;}
+        const auto stratesIt=object->find("strates");
+        if(stratesIt==object->end())
+        {error="transition fixture override cannot find the resolved strate array";return false;}
+        auto* strates=std::get_if<VFJson::Value::Array>(&stratesIt->second.Data);
+        if(!strates||strates->empty())
+        {error="transition fixture override found an empty or invalid strate array";return false;}
+        for(auto& strate:*strates)
+        {
+            auto* strateObject=std::get_if<VFJson::Value::Object>(&strate.Data);
+            if(!strateObject){error="transition fixture contains a malformed strate";return false;}
+            const auto assetIt=strateObject->find("asset");
+            if(assetIt==strateObject->end())continue;
+            auto* asset=std::get_if<VFJson::Value::Object>(&assetIt->second.Data);
+            if(!asset)continue;
+            if(mode>=0)
+            {
+                VFJson::Value value;value.Data=static_cast<double>(mode);
+                (*asset)["TransitionType"]=std::move(value);
+            }
+            if(widthChunks>=0)
+            {
+                VFJson::Value value;value.Data=static_cast<double>(widthChunks);
+                (*asset)["TransitionBlendChunks"]=std::move(value);
+            }
+        }
+        return true;
+    }
+
     bool ParseOptions(int argc,char** argv,FOptions& options)
     {
         const std::filesystem::path executable=std::filesystem::absolute(argv[0]);
@@ -126,6 +161,8 @@ namespace
                     "  --resolved-layout-output=FILE (canonical plan-time layout snapshot)\n"
                     "  --resolved-layout-only (exit after plan and snapshot validation)\n"
                     "  --audit-resolved-layout-boundaries (query Core at each recorded endpoint)\n"
+                    "  --audit-strate-transitions (measure interface crossing, band thickness and holes)\n"
+                    "  --transition-mode=hard|gradient|interleaved --transition-width-chunks=N (fixture override)\n"
                     "  --audit-resolved-layout-passages (capsule, support, route-binding and blocked-control audit)\n"
                     "  --audit-surface-clearance (sample biome terrain/caps against the resolved ceiling)\n"
                     "  --auto-surface-camera (place the 27-tile cube on this seed's surface)\n"
@@ -149,6 +186,21 @@ namespace
             else if(arg=="--audit-resolved-layout-boundaries")options.AuditResolvedLayoutBoundaries=true;
             else if(arg=="--audit-resolved-layout-passages")options.AuditResolvedLayoutPassages=true;
             else if(arg=="--audit-surface-clearance")options.AuditSurfaceClearance=true;
+            else if(arg=="--audit-strate-transitions")options.AuditStrateTransitions=true;
+            else if(arg.starts_with("--transition-mode="))
+            {
+                const std::string_view mode=arg.substr(std::string_view("--transition-mode=").size());
+                if(mode=="gradient")options.TransitionModeOverride=0;
+                else if(mode=="hard")options.TransitionModeOverride=1;
+                else if(mode=="interleaved")options.TransitionModeOverride=2;
+                else {std::fprintf(stderr,"Invalid transition mode: %.*s\n",static_cast<int>(mode.size()),mode.data());return false;}
+            }
+            else if(arg.starts_with("--transition-width-chunks="))
+            {
+                if(!readInt("--transition-width-chunks=",options.TransitionWidthChunksOverride)
+                    ||options.TransitionWidthChunksOverride<0||options.TransitionWidthChunksOverride>64)
+                {std::fprintf(stderr,"transition width chunks must be in 0..64\n");return false;}
+            }
             else if(arg=="--stream-benchmark")options.StreamBenchmark=true;
             else if(arg=="--stream-pipeline")options.StreamPipeline=true;
             else if(arg=="--stream-hash")options.StreamHash=true;
@@ -303,6 +355,10 @@ int main(int argc,char** argv)
     if(options.FloatingIslandsRecipe
         &&!StandaloneWorldAssemblyPrototype::SelectTopStrateAsFloatingIslands(ownerJsonRoot,error))
     {std::fprintf(stderr,"Floating-island recipe selection failed: %s\n",error.c_str());return 2;}
+    if((options.TransitionModeOverride>=0||options.TransitionWidthChunksOverride>=0)
+        &&!OverrideTransitions(ownerJsonRoot,options.TransitionModeOverride,
+            options.TransitionWidthChunksOverride,error))
+    {std::fprintf(stderr,"Transition fixture override failed: %s\n",error.c_str());return 2;}
     if(!StandaloneOwnerLoader::Resolve(ownerJsonRoot,*ownerWorld,error))
     {std::fprintf(stderr,"Owner data load failed: %s\n",error.c_str());return 2;}
     std::printf("[ColdTimeline] stage=owner_data_load end_ms=%.3f\n",
@@ -551,6 +607,6 @@ int main(int argc,char** argv)
         options.RegionCrossing,options.AuditTileShapeReadiness,
         options.DiagnosticSlowShapeCompileMs,options.AuditBasePageEquivalence,
         options.AuditRouteParity,options.AuditResolvedLayoutBoundaries,
-        options.AuditResolvedLayoutPassages,
+        options.AuditResolvedLayoutPassages,options.AuditStrateTransitions,
         &resolvedLayout);
 }

Standalone/Source/StreamBenchmarkPipeline.h

@@ -240,6 +240,172 @@ namespace StandaloneStreamBenchmark
         return Hash;
     }
 
+    inline bool AuditResolvedStrateTransitions(const VoxelForgeCore::World& Field,
+        const FStandaloneOwnerWorld& Owner,
+        const VoxelForgeCore::ResolvedLayoutSnapshotV3& Layout)
+    {
+        constexpr std::int64_t XYExtentMicrometres=256000000;
+        constexpr std::int64_t XYStepMicrometres=8000000;
+        const std::int64_t coreMicrometres=std::max<std::uint32_t>(1,Owner.CoreVoxelSizeMicrons);
+        const std::int64_t zStepMicrometres=std::max<std::int64_t>(1,coreMicrometres/2);
+        const std::int64_t minimumBandMicrometres=2*coreMicrometres;
+        std::uint64_t interfacesPassed=0,totalColumns=0,passageColumnsSkipped=0;
+        std::uint64_t holeColumns=0,airSamples=0,solidSamples=0;
+        bool negativeWidthRejected=false,negativeThinBandRejected=false;
+
+        for(std::size_t interfaceIndex=0;interfaceIndex+1<Layout.strates.size();++interfaceIndex)
+        {
+            const auto& upper=Layout.strates[interfaceIndex];
+            const auto& lower=Layout.strates[interfaceIndex+1];
+            std::int64_t minimumOffset=std::numeric_limits<std::int64_t>::max();
+            std::int64_t maximumOffset=std::numeric_limits<std::int64_t>::min();
+            std::int64_t maximumCrossingDepth=0;
+            std::int64_t minimumUpperThickness=std::numeric_limits<std::int64_t>::max();
+            std::int64_t minimumLowerThickness=std::numeric_limits<std::int64_t>::max();
+            std::uint64_t columns=0,skipped=0,holes=0,air=0,solid=0;
+            bool firstHoleReported=false;
+            const std::int64_t seam=upper.bedrock.bottomMicrometres;
+            const auto passageCoversColumn=[&](std::int64_t xUm,std::int64_t yUm,
+                std::int64_t zMinimumUm,std::int64_t zMaximumUm)
+            {
+                constexpr double Q=VoxelForgeCore::WorldAssemblySubvoxelsPerVoxel;
+                for(const auto& passage:Layout.passages)
+                {
+                    if(passage.upperStrateIndex!=upper.strateIndex
+                        ||passage.lowerStrateIndex!=lower.strateIndex)continue;
+                    for(std::size_t pointIndex=1;pointIndex<passage.controlPoints.size();++pointIndex)
+                    {
+                        const auto& a=passage.controlPoints[pointIndex-1];
+                        const auto& b=passage.controlPoints[pointIndex];
+                        const double ax=a.positionSubvoxels[0]*coreMicrometres/Q;
+                        const double ay=a.positionSubvoxels[1]*coreMicrometres/Q;
+                        const double az=a.positionSubvoxels[2]*coreMicrometres/Q;
+                        const double bx=b.positionSubvoxels[0]*coreMicrometres/Q;
+                        const double by=b.positionSubvoxels[1]*coreMicrometres/Q;
+                        const double bz=b.positionSubvoxels[2]*coreMicrometres/Q;
+                        const double radius=std::max(a.radiusSubvoxels,b.radiusSubvoxels)
+                            *coreMicrometres/Q+750000.0;
+                        if(std::max(az,bz)+radius<zMinimumUm
+                            ||std::min(az,bz)-radius>zMaximumUm)continue;
+                        const double dx=bx-ax,dy=by-ay;
+                        const double lengthSquared=dx*dx+dy*dy;
+                        const double t=lengthSquared>0.0
+                            ?std::clamp(((xUm-ax)*dx+(yUm-ay)*dy)/lengthSquared,0.0,1.0):0.0;
+                        const double ex=xUm-(ax+t*dx),ey=yUm-(ay+t*dy);
+                        if(ex*ex+ey*ey<=radius*radius)return true;
+                    }
+                }
+                return false;
+            };
+
+            for(std::int64_t iy=-XYExtentMicrometres/XYStepMicrometres;
+                iy<=XYExtentMicrometres/XYStepMicrometres;++iy)
+            for(std::int64_t ix=-XYExtentMicrometres/XYStepMicrometres;
+                ix<=XYExtentMicrometres/XYStepMicrometres;++ix)
+            {
+                const std::int64_t xUm=ix*XYStepMicrometres;
+                const std::int64_t yUm=iy*XYStepMicrometres;
+                const auto bands=VoxelForgeCore::EvaluateResolvedLayoutTransitionBandsV1(
+                    upper,lower,Owner.Seed,Layout.strateLayoutChunkSizeMicrometres,xUm,yUm);
+                const std::int64_t offset=bands.upperBedrockBottomMicrometres-seam;
+                minimumOffset=std::min(minimumOffset,offset);
+                maximumOffset=std::max(maximumOffset,offset);
+                maximumCrossingDepth=std::max(maximumCrossingDepth,
+                    bands.crossingDepthMicrometres);
+                minimumUpperThickness=std::min(minimumUpperThickness,
+                    bands.upperBedrockTopMicrometres-bands.upperBedrockBottomMicrometres);
+                minimumLowerThickness=std::min(minimumLowerThickness,
+                    bands.lowerCeilingTopMicrometres-bands.lowerCeilingBottomMicrometres);
+                const std::int64_t zMinimum=std::min(bands.upperBedrockBottomMicrometres,
+                    bands.lowerCeilingBottomMicrometres);
+                const std::int64_t zMaximum=std::max(bands.upperBedrockTopMicrometres,
+                    bands.lowerCeilingTopMicrometres);
+                if(passageCoversColumn(xUm,yUm,zMinimum,zMaximum)){++skipped;continue;}
+
+                ++columns;
+                bool hasHole=false;
+                for(std::int64_t zUm=zMinimum+zStepMicrometres/2;
+                    zUm<zMaximum-zStepMicrometres/2;zUm+=zStepMicrometres)
+                {
+                    const VoxelForgeCore::Vec3d point{
+                        static_cast<double>(xUm)/coreMicrometres,
+                        static_cast<double>(yUm)/coreMicrometres,
+                        static_cast<double>(zUm)/coreMicrometres};
+                    const float density=Field.densityAt(point);
+                    if(!std::isfinite(density)||density>=0.0f)
+                    {
+                        if(!firstHoleReported)
+                        {
+                            std::printf("[StrateTransitionFirstHole] x_um=%lld y_um=%lld z_um=%lld z_min_um=%lld z_max_um=%lld density=%.9g dispatch=%s\n",
+                                static_cast<long long>(xUm),static_cast<long long>(yUm),
+                                static_cast<long long>(zUm),static_cast<long long>(zMinimum),
+                                static_cast<long long>(zMaximum),density,
+                                Field.densityDispatchPathAt(point).c_str());
+                            firstHoleReported=true;
+                        }
+                        hasHole=true;++air;
+                    }
+                    else ++solid;
+                }
+                if(hasHole)++holes;
+            }
+
+            const std::int64_t boundaryPeakToPeak=maximumOffset-minimumOffset;
+            const std::int64_t allowedWidth=upper.transitionMode=="Hard"
+                ||upper.transitionFallsBackToHard?0:upper.transitionWidthMicrometres;
+            if(interfaceIndex==0)
+            {
+                auto wide=Layout;
+                wide.strates[0].transitionMode="Interleaved";
+                wide.strates[0].transitionFallsBackToHard=false;
+                wide.strates[0].transitionWidthMicrometres=8000000;
+                wide.strates[0].transitionInterpenetrationMicrometres=8000001;
+                std::vector<VoxelForgeCore::ResolvedLayoutIssueV2> issues;
+                std::string error;
+                negativeWidthRejected=!wide.validate(
+                    VoxelForgeCore::ResolvedLayoutValidationModeV3::strict,issues,error);
+
+                auto thin=Layout;
+                auto& bedrock=thin.strates[0].bedrock;
+                bedrock.topMicrometres=bedrock.bottomMicrometres+minimumBandMicrometres-1;
+                thin.strates[0].content.bottomMicrometres=bedrock.topMicrometres;
+                negativeThinBandRejected=!thin.validate(
+                    VoxelForgeCore::ResolvedLayoutValidationModeV3::strict,issues,error);
+            }
+            const bool passed=columns>0&&holes==0&&maximumCrossingDepth<=allowedWidth
+                &&minimumUpperThickness>=minimumBandMicrometres
+                &&minimumLowerThickness>=minimumBandMicrometres;
+            interfacesPassed+=passed?1u:0u;
+            totalColumns+=columns;passageColumnsSkipped+=skipped;
+            holeColumns+=holes;airSamples+=air;solidSamples+=solid;
+            std::printf("[StrateTransitionInterface] upper=%d lower=%d mode=%s width_um=%lld max_crossing_depth_um=%lld boundary_peak_to_peak_um=%lld allowed_um=%lld upper_min_band_um=%lld lower_min_band_um=%lld columns=%llu passage_columns=%llu hole_columns=%llu air_samples=%llu status=%s\n",
+                upper.strateIndex,lower.strateIndex,upper.transitionMode.c_str(),
+                static_cast<long long>(upper.transitionWidthMicrometres),
+                static_cast<long long>(maximumCrossingDepth),
+                static_cast<long long>(boundaryPeakToPeak),static_cast<long long>(allowedWidth),
+                static_cast<long long>(minimumUpperThickness),static_cast<long long>(minimumLowerThickness),
+                static_cast<unsigned long long>(columns),static_cast<unsigned long long>(skipped),
+                static_cast<unsigned long long>(holes),static_cast<unsigned long long>(air),
+                passed?"PASS":"FAIL");
+        }
+        const bool controlsPassed=negativeWidthRejected&&negativeThinBandRejected;
+        std::printf("[StrateTransitionNegativeControls] wider_than_declared=%s thinner_than_minimum=%s minimum_band_um=%lld status=%s\n",
+            negativeWidthRejected?"REJECTED":"ACCEPTED",
+            negativeThinBandRejected?"REJECTED":"ACCEPTED",
+            static_cast<long long>(minimumBandMicrometres),controlsPassed?"PASS":"FAIL");
+        const bool passed=!Layout.strates.empty()&&interfacesPassed+1==Layout.strates.size()
+            &&holeColumns==0&&airSamples==0&&controlsPassed;
+        std::printf("[StrateTransitionAuditSummary] interfaces=%llu passed=%llu columns=%llu skipped_passage_columns=%llu hole_columns=%llu air_samples=%llu solid_samples=%llu status=%s\n",
+            static_cast<unsigned long long>(Layout.strates.size()-1),
+            static_cast<unsigned long long>(interfacesPassed),
+            static_cast<unsigned long long>(totalColumns),
+            static_cast<unsigned long long>(passageColumnsSkipped),
+            static_cast<unsigned long long>(holeColumns),
+            static_cast<unsigned long long>(airSamples),
+            static_cast<unsigned long long>(solidSamples),passed?"PASS":"FAIL");
+        return passed;
+    }
+
     inline int RunPipelinedStreamingBenchmark(std::shared_ptr<FStandaloneOwnerWorld> OwnerWorld,
         const VoxelForgeCore::ResolvedWorldSnapshot& CoreSnapshot,
         const FVector& CameraPositionVoxels,int32 WorkerCount,int32 MaxLevel,
@@ -256,6 +422,7 @@ namespace StandaloneStreamBenchmark
         bool bAuditBasePageEquivalence=false,bool bAuditRouteParity=false,
         bool bAuditResolvedLayoutBoundaries=false,
         bool bAuditResolvedLayoutPassages=false,
+        bool bAuditStrateTransitions=false,
         const VoxelForgeCore::ResolvedLayoutSnapshotV3* ResolvedLayout=nullptr)
     {
         using Clock=std::chrono::steady_clock;
@@ -441,6 +608,14 @@ namespace StandaloneStreamBenchmark
             Streamer.Stop();
             std::fprintf(stderr,"[StreamPipeline] full shape build failed: %s\n",BuildError.c_str());return 2;
         }
+        if(bAuditStrateTransitions)
+        {
+            if(ResolvedLayout==nullptr||!CoreSnapshot.resolvedLayout())
+            {Streamer.Stop();std::fprintf(stderr,"[StrateTransitionAudit] missing resolved-layout snapshot\n");return 2;}
+            const bool passed=AuditResolvedStrateTransitions(Shape,World,*ResolvedLayout);
+            Streamer.Stop();
+            return passed?0:11;
+        }
         if(bAuditResolvedLayoutPassages)
         {
             if(ResolvedLayout==nullptr||!CoreSnapshot.resolvedLayout())

Standalone/Source/WorldAssemblyPrototype.h

@@ -801,13 +801,21 @@ namespace StandaloneWorldAssemblyPrototype
             s.transitionBlendChunks=slot.Definition->TransitionBlendChunks;
             s.transitionWidthMicrometres=static_cast<std::int64_t>(s.transitionBlendChunks)*owner.StrateLayoutChunkSizeMicrometres;
             s.transitionWarpAmplitudeMicrometres=s.transitionMode=="Interleaved"
-                ?2*static_cast<std::int64_t>(owner.StrateLayoutChunkSizeMicrometres):0;
-            s.transitionInterpenetrationMicrometres=0;
-            s.transitionHonouredInCore=s.transitionMode=="Hard";
-            s.transitionFallsBackToHard=s.transitionMode!="Hard";
+                ?std::min(s.transitionWidthMicrometres/2,
+                    static_cast<std::int64_t>(owner.StrateLayoutChunkSizeMicrometres)):0;
+            s.transitionInterpenetrationMicrometres=s.transitionMode=="Interleaved"
+                ?s.transitionWidthMicrometres
+                :s.transitionMode=="Gradient"?s.transitionWidthMicrometres/4:0;
+            s.transitionFallsBackToHard=s.transitionMode!="Hard"
+                &&s.transitionWidthMicrometres<=0;
+            s.transitionHonouredInCore=s.transitionMode=="Hard"||!s.transitionFallsBackToHard;
             s.transitionDispatchPath=s.transitionFallsBackToHard
-                ?"declared Gradient/Interleaved recorded; Core uses explicit Hard fallback with zero interpenetration"
-                :"declared Hard transition applied at the strate interface";
+                ?"declared zero-width transition uses explicit Hard fallback"
+                :s.transitionMode=="Hard"
+                    ?"declared Hard transition preserves the flat shared bedrock/ceiling interface"
+                    :s.transitionMode=="Interleaved"
+                        ?"shared composition overlaps both facing bands with deterministic domain-warped fingers inside the declared width"
+                        :"shared composition moves both band faces together with the smooth declared-width transition field";
             s.managerLookup="UVoxelStrateManager selects the slot from the director-resolved layout chunk width";
             s.managerChunkWidthMicrometres=owner.StrateLayoutChunkSizeMicrometres;
             s.dispatchChunkWidthMicrometres=owner.StrateLayoutChunkSizeMicrometres;