streaming: fast-travel near readiness in Unreal (L108)

Policy 3 movement traces (12 s move + 5 s dwell, 3 runs each). Unreal 30 m/s: near LOD0-2
ready while moving 31.6 -> 44.2% (LOD0 15.4 -> 34.7%), world tick p99/max 23.1/28.3 ->
11.3/13.6 ms, dwell completion 3.55 -> 3.22 s; far holes 2.5 -> 4.3%. Walking unchanged (~99%).
Stale work is small (1.9% of moving LOD0 tiles finish out of range); the remaining limit is
sustained generation throughput (8 task slots, p95 worker 105 ms). Near:far stays 4:1.
World unchanged (pinned hashes pass). Fast tier PASS; Linux UE builds.

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

Standalone/Source/StreamBenchmarkPipeline.h

@@ -5631,6 +5631,7 @@ namespace StandaloneStreamBenchmark
                     return 9;
                 }
                 std::size_t NearDesired=0,NearResident=0,FarDesired=0,FarResident=0,FarCovered=0;
+                std::size_t WalkableRingResident=0;
                 double FarStaleAgeSum=0.0,FarStaleAgeMax=0.0;
                 const auto FloorDiv=[](int32 Value,int32 Divisor)
                 {
@@ -5672,6 +5673,19 @@ namespace StandaloneStreamBenchmark
                         }
                     }
                 }
+                for(int32 Dy=-1;Dy<=1;++Dy)
+                for(int32 Dx=-1;Dx<=1;++Dx)
+                {
+                    const FVoxelTileKey WalkableKey(
+                        FIntVector(CurrentDesired.CenterChunk.X+Dx,
+                                   CurrentDesired.CenterChunk.Y+Dy,
+                                   CurrentDesired.CenterChunk.Z),0);
+                    const bool bWalkableKeyDesired=std::find(
+                        CurrentDesired.Tiles.begin(),CurrentDesired.Tiles.end(),WalkableKey)
+                        !=CurrentDesired.Tiles.end();
+                    if(bWalkableKeyDesired&&Resident.contains(WalkableKey))
+                        ++WalkableRingResident;
+                }
                 FarMissingSince.swap(CurrentFarMissing);
                 const double NearReadyPercent=100.0*static_cast<double>(NearResident)
                     /static_cast<double>(std::max<std::size_t>(1,NearDesired));
@@ -5681,12 +5695,15 @@ namespace StandaloneStreamBenchmark
                     /static_cast<double>(std::max<std::size_t>(1,FarDesired));
                 const double FarStaleAgeMean=FarDesired>FarResident
                     ?FarStaleAgeSum/static_cast<double>(FarDesired-FarResident):0.0;
+                const double WalkableRingReadyPercent=100.0
+                    *static_cast<double>(WalkableRingResident)/9.0;
                 if(FarDesired>0&&FarDesired==FarResident&&FirstAllFarReadySeconds<0.0)
                     FirstAllFarReadySeconds=ElapsedSeconds;
                 const char* Phase=ElapsedSeconds<MovingCameraDurationSeconds?"move":"dwell";
-                std::printf("[L79MovingSample] policy=%d speed_mps=%.3f t_s=%.3f phase=%s x_m=%.3f near=%zu/%zu near_ready_pct=%.3f far=%zu/%zu far_missing_pct=%.3f far_covered=%zu/%zu far_hole_pct=%.3f far_stale_mean_s=%.3f far_stale_max_s=%.3f queued_jobs=%d queue_update_ms=%.3f generation_failures=%d\n",
+                std::printf("[L79MovingSample] policy=%d speed_mps=%.3f t_s=%.3f phase=%s x_m=%.3f near=%zu/%zu near_ready_pct=%.3f walkable_ring=%zu/9 walkable_ring_ready_pct=%.3f far=%zu/%zu far_missing_pct=%.3f far_covered=%zu/%zu far_hole_pct=%.3f far_stale_mean_s=%.3f far_stale_max_s=%.3f queued_jobs=%d queue_update_ms=%.3f generation_failures=%d\n",
                     SchedulerPolicy,MovingCameraSpeedMetersPerSecond,ElapsedSeconds,Phase,
                     Camera.X*VoxelMetres,NearResident,NearDesired,NearReadyPercent,
+                    WalkableRingResident,WalkableRingReadyPercent,
                     FarResident,FarDesired,FarMissingPercent,FarCovered,FarDesired,
                     FarHolePercent,FarStaleAgeMean,FarStaleAgeMax,
                     MovingUpdate.NewJobs,UpdateMilliseconds,GenerationFailures);