passages: rounded half-pipe crest (L113, v220); floor bands diagnosed, speed not recovered

Open-air walls: 0.75 m rounded shell, relief fades over the top 0.25 m - the needle spikes are
gone. Every owner plan passes the 15 deg forward-grade check (max ~10.7 deg) and all walk audits.
Floor bands: median 1.25 m interval, ~0.21 m drop on a ~10.4 deg floor = one 0.25 m voxel row
projected along the grade (not control points, not slab thickness) - not yet fixed. Exact
segment-to-tile filter did not reduce candidates; removed. Timings this round are unreliable
(a gitea process used ~43% CPU throughout). Fast tier PASS; Clang/GCC deterministic; UE builds.

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

Standalone/Source/StreamBenchmarkPipeline.h

@@ -3035,7 +3035,7 @@ namespace StandaloneStreamBenchmark
                 const auto controls=passageSplineControls(passage);
                 const auto floorProfile=passageSplineFloorProfile(passage);
                 const auto segments=VoxelForgeCore::PassageSpline::BuildSegments(
-                    controls,routeEnd,1.0,1.0,floorProfile);
+                    controls,routeEnd,8.0,1.0,floorProfile,0.025);
                 const auto consider=[&](double distance,double radius)
                 {
                     minimumRadius=std::min(minimumRadius,radius);
@@ -3070,7 +3070,7 @@ namespace StandaloneStreamBenchmark
                 const auto controls=passageSplineControls(passage);
                 const auto floorProfile=passageSplineFloorProfile(passage);
                 const auto segments=VoxelForgeCore::PassageSpline::BuildSegments(
-                    controls,routeEnd,1.0,1.0,floorProfile);
+                    controls,routeEnd,8.0,1.0,floorProfile,0.025);
                 const auto effectiveCenterZ=[&](const auto& point,double plannedFloor)
                 {
                     return plannedFloor+passageTubeDepthAt(point[3],bodyDepth);
@@ -3125,7 +3125,7 @@ namespace StandaloneStreamBenchmark
                     const std::size_t routeEnd=std::clamp<std::size_t>(
                         passage.lowerMouthControlIndex,1,passage.controlPoints.size()-1);
                     const auto segments=VoxelForgeCore::PassageSpline::BuildSegments(
-                        controls,routeEnd,1.0,1.0,floorProfile);
+                        controls,routeEnd,8.0,1.0,floorProfile,0.025);
                     if(!segments.empty())
                     {
                         blend.mouthX=segments.front().a[0];
@@ -3232,16 +3232,6 @@ namespace StandaloneStreamBenchmark
                         bestRoundDistance+radius);
                     const double verticalWallAlignment=std::clamp(
                         -(zMetres-centerZ)/distanceToCenter,0.0,1.0);
-                    const double wallReliefWeight=0.05+0.95
-                        *(1.0-verticalWallAlignment);
-                    const float relief=VF_FieldPassageWallRelief(
-                        static_cast<float>(xMetres/coreMetres),
-                        static_cast<float>(yMetres/coreMetres),
-                        static_cast<float>(zMetres/coreMetres),
-                        static_cast<std::uint32_t>(World.Seed));
-                    const double roughRoundDistance=bestRoundDistance
-                        +static_cast<double>(std::clamp(relief,-1.0f,1.0f))
-                            *WallReliefMetres*wallReliefWeight;
                     const auto& aFloor=route[bestSegment-1];
                     const auto& bFloor=route[bestSegment];
                     const double floorDx=bFloor.x-aFloor.x;
@@ -3252,6 +3242,21 @@ namespace StandaloneStreamBenchmark
                             +(yMetres-aFloor.y)*floorDy)/horizontalSquared,0.0,1.0):t;
                     const double floorCenterZ=passageFloorAtXY(passageIndex,
                         xMetres,yMetres,std::lerp(aFloor.floorZ,bFloor.floorZ,floorT));
+                    const double wallElevationMetres=zMetres-floorCenterZ;
+                    const double crestFade=std::clamp((1.0-wallElevationMetres)/0.25,
+                        0.0,1.0);
+                    const double smoothCrestFade=crestFade*crestFade
+                        *(3.0-2.0*crestFade);
+                    const double wallReliefWeight=(0.05+0.95
+                        *(1.0-verticalWallAlignment))*smoothCrestFade;
+                    const float relief=VF_FieldPassageWallRelief(
+                        static_cast<float>(xMetres/coreMetres),
+                        static_cast<float>(yMetres/coreMetres),
+                        static_cast<float>(zMetres/coreMetres),
+                        static_cast<std::uint32_t>(World.Seed));
+                    const double roughRoundDistance=bestRoundDistance
+                        +static_cast<double>(std::clamp(relief,-1.0f,1.0f))
+                            *WallReliefMetres*wallReliefWeight;
                     const double floorDistance=floorCenterZ-zMetres;
                     const double blend=std::max(CornerBlendMetres-
                         std::abs(roughRoundDistance-floorDistance),0.0)/CornerBlendMetres;
@@ -4033,6 +4038,7 @@ namespace StandaloneStreamBenchmark
             };
             constexpr double PassageShellAuditSpacingMetres=0.25;
             constexpr std::array<double,2> PassageShellAuditDepthsMetres{{0.125,0.375}};
+            constexpr float PassageShellDensityTolerance=1.0e-6f;
             const auto expectedPassageShellAt=[&](double xMetres,double yMetres,
                 double zMetres)
             {
@@ -4170,8 +4176,8 @@ namespace StandaloneStreamBenchmark
                                     const bool shellExpected=depth+0.011
                                         <expectedFloorThickness(along,depth);
                                     const float density=Field.densityAt(position);
-                                    if((shellExpected&&density>=0.0f)
-                                        ||(!shellExpected&&density<0.0f))
+                                    if((shellExpected&&density>=PassageShellDensityTolerance)
+                                        ||(!shellExpected&&density<-PassageShellDensityTolerance))
                                     {
                                         ++audit.floorViolations;
                                         if(audit.firstViolationCount<audit.firstViolations.size())
@@ -4227,8 +4233,10 @@ namespace StandaloneStreamBenchmark
                             const int shellExpected=expectedPassageShellAt(
                                 sampleX,sampleY,sampleZ);
                             if(shellExpected>=0
-                                &&((shellExpected==1&&density>=0.0f)
-                                    ||(shellExpected==0&&density<0.0f)))
+                                &&((shellExpected==1
+                                        &&density>=PassageShellDensityTolerance)
+                                    ||(shellExpected==0
+                                        &&density<-PassageShellDensityTolerance)))
                             {
                                 ++audit.wallViolations;
                                 if(audit.firstWallViolationCount