research(intervals): one-day spike -- whole near region in 241 ms (6 workers), exact signs, far proxy 8.6 ms

Standalone C++20 (MSVC /O2 /arch:AVX2), no Unreal. A 372-shape corpus (rooms at the hardest
profile's scale, winding tunnels, pillars, stalactites, shelves, floating masses, thin strata,
rotated shapes, crowded junctions, craters), built two ways: point-by-point reference vs column
intervals on 3 axes + 64-bit sign words + bit-scanned active cells + meshing from analytic crossings.
64 m near region at 25 cm (17.4 M nodes), 5 seeds, fresh processes:
  workers  near CPU total (median/p95/worst)  interval stage   mesh stage (single-threaded)
  1        349 / 358 / 358 ms                  154 ms           188 ms
  6        241 / 280 / 288 ms                   48 ms           191 ms
  8        240 / 271 / 277 ms                   43 ms           193 ms
Near mesh ~563k triangles, 13.5 MB; total output 19.9 MB; busiest line 58 candidates (< 64).
Correctness: 0 sign mismatches vs reference at every node, 0 missing crossings/open contours, thin
strata with no lattice node inside get explicit triangles (dropping them is caught), same hash on
1/6/8 workers and a repeated run. Far field: 47k nodes / 92k patches in ~8.6 ms, but fixed-grid
ellipsoid sheets, not a validated cave hierarchy: unproven. No noise detail in this corpus.

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

Saved/Research/intervals/bench_seed4_w8.json

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