wip(assembler): M1 repair round -- raised block and cliff fixed; native 7x faster than legacy

Luna, M1 repair round: the rectangular raised block and the broken cliff shared one cause,
a type-2 solid AABB in the generated plan; it is now a tapered, terrain-following shelf, and
a negative-control audit catches the old box behaviour; seam classification check passes.
Bound audit 298 boxes / 8,046 samples, 0 misses. Evaluator and 120-tile density/mesh/payload/
topology hashes identical at W1/W8/W16. Cave regression: walkability 5,642/5,642, 64/64 tiles.
Legacy mismatch unchanged (0 biome mismatches, 18.14% signs).
Speed (matched workloads): 120-tile full detail 0.089 s native vs 0.625 s legacy; 529-tile
clipmap 3.858 s vs 11.687 s -- 2.29 s above the ~1.57 s aim; LOD8 dominates (165 unknown
tiles, 13.27 M field calls, 10.88 M column-cache misses).
My capture review: coast matches legacy closely; surface clean but a dark flat slab on the far
horizon; cliff shelf renders as a stack of thin plates with back faces showing (sub-voxel
shelf thickness suspected).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Standalone/Research/WorldAssemblerM1/round3/performance/cliff-native.txt

@@ -0,0 +1,31 @@
+[ProcessControls] priority_class=Normal priority_source=argument affinity_mask=0xFFFF affinity_source=argument requested_affinity=0xFFFF system_affinity=0xFFFF
+[ColdTimeline] stage=owner_data_load begin_ms=0.058
+[ColdTimeline] stage=owner_data_load end_ms=16.138
+[WorldAssemblerPrototype] recipe_version=1 evaluator_version=3 strata=1 biomes=4 strate_index=1 chunk_z=-16..-79 serialized_bytes=4524 recipe_hash=dbbc0ac1267bbb97 plan_hash=b5f74995825f80c0 manifest_hash=023cfa0da07fc3a6 source=owner_surface_params_and_biome_map route_points=0 features=1
+[WorldAssemblerPlanTiming] total_ms=6.957 status=PASS
+[ConfigureProfile] stage=desired_tiles_and_bounds tiles=120 duration_ms=0.065
+[ConfigureProfile] stage=snapshot_and_build_request duration_ms=0.866
+[ColdTimeline] stage=shape_compile begin_ms=24.032
+[GridStairDistanceRepair] exact_endpoint_proxies=0 occupancy_corrections=0
+[Walkability] PASS 5642/5642 passage centerline samples remain open; native landing floors retained
+[ShapeProfile] local_primitives=33.368ms line_bins=4.112ms rock_lines_wall=8.067ms rock_lines_worker=9.636ms candidate_axes_wall=14.039ms candidate_axes_worker=1.100ms candidate_merge_wall=14.904ms candidate_merge_worker=3.235ms candidate_merge_serial=0.116ms detail_lines_wall=8.722ms detail_lines_worker=12.508ms
+[ShapeSubstage] detail_apply=8.728ms sign_edge_distances=1.176ms passage_validation=1.017ms shared_field_primitives=0.022ms far_parents=0.000ms
+[ShapeAllocation] words=5.20MiB candidate_axis_words=5.20MiB proxy=33.91MiB primitives=0.13MiB spatial_bins=27116 spatial_bin_refs=54379 spatial_bin_capacity=109288 inline_bins=26920 overflow_bins=196 far_primitive_build=0.000ms far_bin_rebuild=0.000ms
+[ShapeCompile] primitives=297 rooms=49 tunnels=50 passages=2 nodes=17779581 packed=5.20 MiB surface_proxy_nodes=0 proxy_address_capacity=33.91 MiB workers=16
+[ShapeStage] local-shapes=37.488 ms intervals+signs=38.626 ms surface-band=9.905 ms far-parents=0.000 ms total=88.025 ms candidates=0 flips=0 walk=5642/5642
+[RoomFloorJoinAudit] automatic_room_overlaps=2 thin_positive_support_overlays=0 status=PASS
+[FloorSlopeJoinAudit] raw_unmarked_max_delta=3.28058 vox generated_tangent_delta=0.00000 vox bend_direction_slope_change=0.15524 vox marked_max_delta=0.00000 vox marked_joins=0 threshold=0.750 status=PASS
+[FloorProfileBlend] c1_segments=227 max_curve_deviation=0.753 vox threshold=2.000 status=PASS
+[TunnelRadiusAudit] shared_joins=175 legacy_fixed_segment_max_step=2.7093 vox smoothed_profile_max_step=1.5425 vox tapered_endpoint_max_delta=0.000000 vox radius_slope_join_delta=0.00000000 floor_endpoint_max_delta=0.000000 vox floor_slope_join_delta=0.00000 unmarked_floor_slope_delta=0.00000 marked_floor_slope_delta=0.00000 marked_slope_joins=0 smooth_union_growth_bound=0.2500 vox thresholds=(0.005,0.000001,0.005,0.25) status=PASS
+[TunnelBendAudit] sharpest_bend=49.12 deg centerline=(-932.38,-73.30,-2336.41) vox tangent=(0.4895,0.4468,-0.7488) camera_yaw=47.62 camera_pitch=-48.49
+[ColdTimeline] stage=shape_compile end_ms=112.109 duration_ms=88.077
+[ShapeRegion] fine_tiles=120 bounds=(-768,128,-1920)..(-512,384,-1664) clip=(-57344,-49152,-8192)..(49152,57344,0)
+Standalone clip override: exported radius=6 (112 m cube) -> radius=1 (32 m LOD0 cube), voxel size=25 cm.
+[StreamBenchmarkConfig] clip_radius=1 lod0_cube=32m voxel=25cm fullres_levels=2 max_level_filter=1 workers=16 full_detail_tiles=120 desired_tiles=120 variant=base uv=full colors=full material_groups=full hash=off
+[StreamFullDetail] wall=0.786s generated=120/120 resident_tiles_cpu_only=1 hash=off
+[WorldAssemblerTilePipeline] full_detail_tiles=120 solid_boxes=191 air_boxes=1 mixed_boxes=56 unknown_boxes=0 whole_tile_skips=89 field_calls=1525225 column_cache_hits=110438 column_cache_misses=1417570 column_compute_worker_ms=10907.867 classification_worker_ms=960.065 meshing_worker_ms=10340.275
+[PlayerNeighborhood] lod0_tiles=27/27 mesh_ready=0.036s collision_cook=unavailable_in_standalone
+[StreamFullClipmap] wall=0.786s generated=120/120 worker_sum=11.288s worker_busy=89.8% worker_idle=10.2% payload_alloc=4.32MiB viewer_output=2.11MiB tiles=120 hash=off
+[StreamCacheUse] hits=0 requested=120
+[StreamLevel] lod=0 tiles=64 samples=0.086M worker_sum=0.694s first_ready=0.015s complete=0.141s worker_busy=30.8% payload_alloc=0.20MiB viewer_output=0.10MiB vertices=2377 indices=10473 hash=off
+[StreamLevel] lod=1 tiles=56 samples=1.243M worker_sum=10.594s first_ready=0.036s complete=0.785s worker_busy=84.3% payload_alloc=4.12MiB viewer_output=2.02MiB vertices=47375 indices=225756 hash=off