Package 10.8.1–10.8.2: real-map corpus and scientific isosurface convergence gate

[aliorhun]

Package 10.8.1–10.8.2 — real-map corpus and required scientific convergence gate

Implementation: The current production volume-iso-worker.js final marching-tetrahedra algorithm is invoked in a new analytic/real-map numerical gate. The P10.7 octree remains preview-only.

• Analytic reference: signed-distance sphere evaluated at 16³, 24³, 32³. Fail CI if maximum radial vertex error ≥0.025 Å, surface relative error ≥8%, enclosed-volume relative error ≥10%, or fine-resolution measures do not improve on coarse.
• Independent crystallographic data: real 5i55 partial monoclinic CCP4 fixture, and real 5wkd C2 MTZ FWT/PHWT and DELFWT/PHDELWT coefficients converted to 64³ density maps by pinned Gemmi 0.7.5 (not by JavaScript FFT).
• Real-map measurements: physically matched resampling at 16³/24³/32³, production triangle cap enforced, surface areas, voxel-quadrature occupied volume, source-field scalar residual, CUBE/XSF coordinate+voxel round trips, machine-readable JSON artifact.
• Required PR CI: Validate and deploy crystal studio runs the gate; malformed, nonfinite, truncated, degenerate or analytically inaccurate results fail CI. Existing Gemmi MTZ/CCP4/Chromium gates are retained.

Measured experimental resolution sensitivity (16³ → 32³)

Real source	Absolute relative surface-area change	Thresholded volume change
5i55 partial CCP4	3.668%	2.116%
5wkd FWT/PHWT	46.270%	24.229%
5wkd DELFWT/PHDELWT	3.790%	1.685%

Scientific finding: The refinement-weighted 5wkd FWT surface is not geometrically converged at these tested resolutions. A passing CI means the implementations, analytic shape and reproducible measurement/reporting gates passed; it does not mean every experimental surface converged. These between-grid changes are not Hausdorff guarantees. The real-map threshold is chosen near signed density peaks to keep measurements within the production 75,000-triangle safety budget.

Open work: higher-resolution 5wkd convergence plus independent experimental CHGCAR/CUBE/XSF and wider MRC vendor corpora; manifold/oriented volume on real closed surfaces; multi-GPU/OS benchmark matrix.

Unmerged pending browser CI.