proto: first liminal fixtures - flat field + monolith, periodic hills, raised road in fog (L141)

Standalone only: fixtures, liminal_road_override (fillDais), --audit-liminal-road-walk, capture-only distance fog.
Road 65 m x 6 m, 22 m up, capsule walk 127/127. Owner hashes unchanged (v227), fast tier, Clang/GCC green.
Hills repeat every 80 m but the capture reaches 56 m, so only one rise shows. Also R48 (who owns the tunnel mouth):
recommends a bounded joint plan of passage ports and layer landing candidates.

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

Standalone/Source/StreamBenchmarkHeadless.cpp

@@ -108,6 +108,7 @@ namespace
         bool ResolvedLayoutOnly=false;
         bool AuditResolvedLayoutBoundaries=false;
         bool AuditResolvedLayoutPassages=false;
+        bool AuditLiminalRoadWalk=false;
         bool AuditSurfaceClearance=false;
         bool AuditStrateTransitions=false;
         int TransitionModeOverride=-1;
@@ -1447,6 +1448,7 @@ namespace
                     "  --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-liminal-road-walk (capsule, support, width and grade audit for the liminal road)\n"
                     "  --audit-heightfield-profile (brute-force the profiled field intervals and route)\n"
                     "  --audit-motif-intervals (brute-force motif bounds, BVH and shape-free guards)\n"
                     "  --audit-landmark-reachability (capsule, support, grade and buried-L43 control)\n"
@@ -1494,6 +1496,7 @@ namespace
             else if(arg=="--resolved-layout-only")options.ResolvedLayoutOnly=true;
             else if(arg=="--audit-resolved-layout-boundaries")options.AuditResolvedLayoutBoundaries=true;
             else if(arg=="--audit-resolved-layout-passages")options.AuditResolvedLayoutPassages=true;
+            else if(arg=="--audit-liminal-road-walk")options.AuditLiminalRoadWalk=true;
             else if(arg=="--native-owner-fi")options.NativeOwnerFloatingIslandsRecipe=true;
             else if(arg=="--density-dispatch-report")
             {options.DensityDispatchReport=true;options.StreamHash=true;options.StreamHashTiles=true;}
@@ -1875,7 +1878,13 @@ int main(int argc,char** argv)
             &&!StandaloneWorldAssemblyPrototype::ValidateExportedCorePlanMatchesOwner(
                 *ownerWorld,worldAssembly,resolvedLayout,error))
         {std::fprintf(stderr,"Unreal-resolved Core plan/owner slot validation failed: %s\n",error.c_str());return 2;}
-        if(!std::holds_alternative<std::nullptr_t>(ownerJsonRoot.Get("motif_family_override").Data))
+        const bool hasMotifFamily=!std::holds_alternative<std::nullptr_t>(
+            ownerJsonRoot.Get("motif_family_override").Data);
+        const bool hasLiminalRoad=!std::holds_alternative<std::nullptr_t>(
+            ownerJsonRoot.Get("liminal_road_override").Data);
+        if(hasMotifFamily&&hasLiminalRoad)
+        {std::fprintf(stderr,"motif_family_override and liminal_road_override cannot be combined\n");return 2;}
+        if(hasMotifFamily)
         {
             std::vector<VoxelForgeCore::ResolvedLayoutStampRequestV1> requests;
             if(!StandaloneWorldAssemblyPrototype::BuildMotifFamilyRequests(ownerJsonRoot,
@@ -1903,6 +1912,25 @@ int main(int argc,char** argv)
                     static_cast<unsigned long long>(motif.irregularitySeed));
             }
         }
+        if(hasLiminalRoad)
+        {
+            std::vector<VoxelForgeCore::ResolvedLayoutStampRequestV1> requests(1);
+            if(!StandaloneWorldAssemblyPrototype::BuildLiminalRoadRequest(ownerJsonRoot,
+                    *ownerWorld,worldAssembly,resolvedLayout,requests.front(),error)
+                ||!VoxelForgeCore::ResolveResolvedLayoutStampsV1(
+                    resolvedLayout,seed,requests,error))
+            {std::fprintf(stderr,"Liminal road resolution failed: %s\n",error.c_str());return 2;}
+            const auto& road=resolvedLayout.stamps.front();
+            std::printf("[LiminalRoadResolved] vocabulary=%u id=%s strate=%d shape=rounded_dais "
+                "center_m=(%.3f,%.3f,%.3f) top_m=%.3f span_m=%.3f width_m=%.3f "
+                "grade_deg=0.000 placement=free route_keepout=PASS band_clearance=PASS status=PASS\n",
+                resolvedLayout.stampVocabularyVersion,road.stableId.c_str(),road.strateIndex,
+                road.positionMicrometres[0]/1.0e6,road.positionMicrometres[1]/1.0e6,
+                road.positionMicrometres[2]/1.0e6,
+                (road.positionMicrometres[2]+road.halfExtentsMicrometres[2])/1.0e6,
+                2.0*road.halfExtentsMicrometres[0]/1.0e6,
+                2.0*road.halfExtentsMicrometres[1]/1.0e6);
+        }
         if(options.LandmarkChamberDemo)
         {
             std::vector<VoxelForgeCore::ResolvedLayoutStampRequestV1> requests;
@@ -2404,5 +2432,5 @@ int main(int argc,char** argv)
         options.MovingCameraSpeedMetersPerSecond,options.MovingCameraDurationSeconds,
         options.MovingCameraDwellSeconds,options.ColdWorkerTimeline,
         options.AuditPassageSourceClamp,options.AuditPassageCarveReach,
-        options.AuditPassageTileSeams);
+        options.AuditPassageTileSeams,options.AuditLiminalRoadWalk);
 }