feat(core): reachable SW landmark chamber demo with a reachability audit (L45); research R12

Stamp vocabulary v2; the flagged SW demo opens through a side-facing portal and a bent ramp (max 14 deg,
two landings) into a 17 x 15 m chamber with a rock dais. New reachability audit: a capsule surface search
from walkable ground near the arrival mouth to the chamber floor (66 samples, 0 blocked/unsupported); the
buried L43 layout fails it. Demo off: owner hashes identical to L44. fast/medium/full PASS (Clang+GCC).
Research R12 (read-only): composite cavern-graph generator design and slices.

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

Standalone/Core/src/ResolvedLayoutInternal.h

@@ -830,8 +830,9 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
         if(stampVocabularyVersion!=0)
             add("stamp_vocabulary_version","stamp vocabulary version is set without any stamp records");
     }
-    else if(stampVocabularyVersion!=ResolvedLayoutStampVocabularyVersionV1)
-        add("stamp_vocabulary_version","resolved stamps require vocabulary version 1");
+    else if(stampVocabularyVersion!=ResolvedLayoutStampVocabularyVersionV1
+        &&stampVocabularyVersion!=ResolvedLayoutStampVocabularyVersionV2)
+        add("stamp_vocabulary_version","resolved stamps require supported vocabulary version 1 or 2");
     std::vector<std::string> stampIds;
     for(const auto& stamp:stamps)
     {
@@ -1065,6 +1066,20 @@ bool ResolveResolvedLayoutStampsV1(ResolvedLayoutSnapshotV3& layout,std::int32_t
     layout=std::move(candidate);return true;
 }
 
+bool ResolveResolvedLayoutStampsV2(ResolvedLayoutSnapshotV3& layout,std::int32_t seed,
+    std::span<const ResolvedLayoutStampRequestV1> requests,std::string& error)
+{
+    if(!ResolveResolvedLayoutStampsV1(layout,seed,requests,error))return false;
+    if(requests.empty())return true;
+    ResolvedLayoutSnapshotV3 candidate=layout;
+    candidate.stampVocabularyVersion=ResolvedLayoutStampVocabularyVersionV2;
+    if(!candidate.finalize(error))return false;
+    std::vector<ResolvedLayoutIssueV2> issues;std::string strictError;
+    if(!candidate.validate(ResolvedLayoutValidationModeV3::strict,issues,strictError))
+    {error="strict stamp vocabulary-2 validation failed: "+strictError;return false;}
+    layout=std::move(candidate);return true;
+}
+
 ResolvedLayoutStampPlacementAuditV1 AuditResolvedLayoutStampPlacementV1(
     const ResolvedLayoutSnapshotV3& layout)
 {

Standalone/Core/src/ShapeWorldInternal.h

@@ -3339,6 +3339,10 @@ private:
                 return result;
             }
         QueryStampSpatialNode(0,minimum,maximum,result);
+        // Stamp union/carve composition follows canonical stable-ID order. The BVH query
+        // order is spatial and can differ per tile, which would let a later carve erase a
+        // fill on meshed tiles even though unscoped density queries use the canonical order.
+        std::sort(result.begin(),result.end());
         return result;
     }
 
@@ -5673,9 +5677,14 @@ private:
         case VoxelForgeCore::ResolvedSdfStampKindV1::fillPillar:
             distance=StampPillarSdf(localX,localY,localZ,stamp.halfExtentsVoxels);break;
         case VoxelForgeCore::ResolvedSdfStampKindV1::fillDais:
-            distance=StampRoundedBoxSdf(localX,localY,localZ,stamp.halfExtentsVoxels,
-                std::min(0.35f,std::min({stamp.halfExtentsVoxels[0],
-                    stamp.halfExtentsVoxels[1],stamp.halfExtentsVoxels[2]})*0.15f));break;
+            if(ResolvedLayout&&ResolvedLayout->stampVocabularyVersion
+                >=VoxelForgeCore::ResolvedLayoutStampVocabularyVersionV2)
+                distance=StampEllipsoidSdf(localX,localY,localZ,stamp.halfExtentsVoxels);
+            else
+                distance=StampRoundedBoxSdf(localX,localY,localZ,stamp.halfExtentsVoxels,
+                    std::min(0.35f,std::min({stamp.halfExtentsVoxels[0],
+                        stamp.halfExtentsVoxels[1],stamp.halfExtentsVoxels[2]})*0.15f));
+            break;
         default:return std::numeric_limits<float>::infinity();
         }
         if(stamp.irregularityAmplitudeVoxels>0.0f)

Standalone/Core/src/VoxelForgeCore.cpp

@@ -989,6 +989,15 @@ namespace VoxelForgeCore
     const ResolvedLayoutSnapshotV3* ResolvedWorldSnapshot::resolvedLayout() const noexcept
     { return data_?data_->resolvedLayout.get():nullptr; }
 
+    ResolvedWorldSnapshot ResolvedWorldSnapshot::withResolvedLayout(
+        const ResolvedLayoutSnapshotV3& layout) const
+    {
+        if(!data_)return {};
+        auto copy=std::make_shared<Data>(*data_);
+        copy->resolvedLayout=std::make_shared<ResolvedLayoutSnapshotV3>(layout);
+        return ResolvedWorldSnapshot(std::move(copy));
+    }
+
     ResolvedWorldSnapshot ResolvedWorldSnapshot::withoutResolvedLayoutPassages() const
     {
         if(!data_||!data_->resolvedLayout)return {};
@@ -2222,6 +2231,40 @@ namespace VoxelForgeCore
                         RelevantMinimum=std::min(RelevantMinimum,FeatureMinimum);
                         RelevantMaximum=std::max(RelevantMaximum,FeatureMaximum);
                     }
+                    // The native heightfield band only covers the owner terrain and its
+                    // manifest features. Resolved SDF stamps can carve below that band or
+                    // add a floor there, so include every overlapping stamp's bounded Z
+                    // support before clipping marching-cubes samples.
+                    if(impl_->resolvedLayout&&impl_->owner->CoreVoxelSizeMicrons>0)
+                    {
+                        const double MicronsToVoxels=1.0
+                            /static_cast<double>(impl_->owner->CoreVoxelSizeMicrons);
+                        const double TileMinimumX=static_cast<double>(origin.X-step);
+                        const double TileMinimumY=static_cast<double>(origin.Y-step);
+                        const double TileMaximumX=static_cast<double>(origin.X+extent+step);
+                        const double TileMaximumY=static_cast<double>(origin.Y+extent+step);
+                        for(const auto& Stamp:impl_->resolvedLayout->stamps)
+                        {
+                            if(Stamp.strateIndex!=PlanIt->strateIndex)continue;
+                            const double MinimumX=Stamp.boundsMinimumMicrometres[0]
+                                *MicronsToVoxels;
+                            const double MaximumX=Stamp.boundsMaximumMicrometres[0]
+                                *MicronsToVoxels;
+                            const double MinimumY=Stamp.boundsMinimumMicrometres[1]
+                                *MicronsToVoxels;
+                            const double MaximumY=Stamp.boundsMaximumMicrometres[1]
+                                *MicronsToVoxels;
+                            if(MaximumX<TileMinimumX||MinimumX>TileMaximumX
+                                ||MaximumY<TileMinimumY||MinimumY>TileMaximumY)continue;
+                            const double MinimumZ=Stamp.boundsMinimumMicrometres[2]
+                                *MicronsToVoxels;
+                            const double MaximumZ=Stamp.boundsMaximumMicrometres[2]
+                                *MicronsToVoxels;
+                            if(MaximumZ<TileMinimumZ||MinimumZ>TileMaximumZ)continue;
+                            RelevantMinimum=std::min(RelevantMinimum,MinimumZ);
+                            RelevantMaximum=std::max(RelevantMaximum,MaximumZ);
+                        }
+                    }
                     if(std::isfinite(RelevantMinimum)&&std::isfinite(RelevantMaximum))
                     {
                         const int32 NativeBandMinimum=FMath::FloorToInt(RelevantMinimum)-step;