core: coarser smooth-route tolerance + shell support bound (L119, evaluator v224)

Chord error 2.5 -> 10 cm, shell work skipped outside the 0-0.75 m band. Sweep pairs -39%, prepare -60%,
near-ready 3-8% faster than L115 but still +13..+22% vs L109. Floor offset 7.88 mm; captures match L115
by eye; fast tier, walk audits, Clang/GCC W1/W8/W12 determinism green. Not for merge yet.

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,8.0,1.0,floorProfile,0.025);
+                    controls,routeEnd,8.0,1.0,floorProfile,0.100);
                 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,8.0,1.0,floorProfile,0.025);
+                    controls,routeEnd,8.0,1.0,floorProfile,0.100);
                 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,8.0,1.0,floorProfile,0.025);
+                        controls,routeEnd,8.0,1.0,floorProfile,0.100);
                     if(!segments.empty())
                     {
                         blend.mouthX=segments.front().a[0];
@@ -3605,7 +3605,45 @@ namespace StandaloneStreamBenchmark
                             }
                             else ++audit.missingFloorSamples;
                         }
-                        if(i%4!=0)continue;
+                    }
+                }
+                // Keep wall probe density tied to route distance, not to the number
+                // of adaptive spline segments. A coarser chord tolerance may leave
+                // long segments around a mouth; fixed stations still exercise the
+                // same wall geometry without weakening the coverage requirement.
+                for(std::size_t endpoint=0;endpoint<2;++endpoint)
+                {
+                    for(double localDistance=0.0;
+                        localDistance<=PassageMouthProfileReachMetres+1.0e-9;
+                        localDistance+=1.0)
+                    {
+                        const double routeDistance=endpoint==0?localDistance
+                            :lowerMouthDistance-localDistance;
+                        if(routeDistance<0.0||routeDistance>lowerMouthDistance)continue;
+                        const auto upper=std::lower_bound(path.begin(),path.end(),routeDistance,
+                            [](const FProfilePose& pose,double value)
+                            {return pose.distance<value;});
+                        const auto b=upper==path.end()?path.end()-1:upper;
+                        const auto a=b==path.begin()?b:b-1;
+                        const double span=b->distance-a->distance;
+                        const double t=span>1.0e-12
+                            ?std::clamp((routeDistance-a->distance)/span,0.0,1.0):0.0;
+                        const double dx=b->x-a->x,dy=b->y-a->y;
+                        const double tangentLength=std::hypot(dx,dy);
+                        if(tangentLength<=1.0e-6)
+                        {
+                            audit.missingWallSamples+=2;
+                            continue;
+                        }
+                        const double nx=-dy/tangentLength,ny=dx/tangentLength;
+                        FProfilePose pose;
+                        pose.distance=routeDistance;
+                        pose.x=std::lerp(a->x,b->x,t);
+                        pose.y=std::lerp(a->y,b->y,t);
+                        pose.z=std::lerp(a->z,b->z,t);
+                        pose.floorZ=std::lerp(a->floorZ,b->floorZ,t);
+                        pose.radius=std::lerp(a->radius,b->radius,t);
+                        pose.segmentIndex=t<0.5?a->segmentIndex:b->segmentIndex;
                         for(std::size_t side=0;side<2;++side)
                         {
                             const double sign=side==0?-1.0:1.0;
@@ -3613,10 +3651,12 @@ namespace StandaloneStreamBenchmark
                             // above its floor. Probe at mid-wall height so this check
                             // measures those walls instead of the absent roof-height
                             // shell at the centreline.
-                            const double radius=findWallRadius(pose,sign*nx,sign*ny,0.50);
+                            const double radius=findWallRadius(
+                                pose,sign*nx,sign*ny,0.50);
                             if(std::isfinite(radius))
                             {
-                                wallProfiles[endpoint][side].push_back({localDistance,radius});
+                                wallProfiles[endpoint][side].push_back(
+                                    {localDistance,radius});
                                 ++audit.wallSamples;
                             }
                             else ++audit.missingWallSamples;