EM18B: one-way distance fidelity and the contact-verdict error of collision proxies, Study 2, pre-registered campaign data and code

Data and code of the pre-registered measurement campaign EM18B (run EM18B-20261024T210621Z-885de1f, 25 to 26 October 2026), the second study of a programme whose first study, EM18, is deposited as 10.5281/zenodo.23605693 and is not amended here. For 72 rigid watertight triangle meshes of the Thingi10K dataset, disjoint from the first study's and drawn by a seeded rule into three concavity strata of 24, collision proxies built by QEM decimation, V-HACD v4.1.0 at three settings and CoACD 1.0.14 at matched memory, together with the convex hull and an oriented box, are graded against exact volumetric contact on the source over isotropic approach lines, at directional separations and depths of 0.0005 to 0.02 of the source's bounding-box diagonal, with an icosphere probe at three sizes and a plate probe at one. Convex parts are admitted by a corrected convexity gate. The registered tests ask whether the union-boundary one-way Chamfer distance from proxy to source orders proxies of matched memory consistently with their near-contact verdict error on all cross-arm pairs and on pairs whose proxies come from different tools, and whether excess beyond the contact band is part of the reason. The registered outcomes are recorded verbatim in registration_EM18B_RESULT.md, with the adversarial review of the results. The deposit holds the registration verbatim with its six dated amendments, the code at the pinned commit and the five files added afterwards by amendment, every built proxy, the poses and truth verdicts, every proxy verdict, the readers' input exactly as read and the output of each single reader run, the campaign records with every unit marker and log, a determinism check of CoACD rebuilt outside the run, and a diagnosis of a hang in CoACD's default setting, which is not registered and decides nothing. Raw models are not redistributed; their origins and SHA-256 values are listed. Licence: CC BY 4.0; the proxies are derived works of the Thingi10K models, credited per source with each model's licence (Creative Commons Attribution, CC0 or BSD) in LICENSES.md.