NSBH merger-branch classification component gate — 27 September 2026

The frozen specification was committed as 49054e8 before native comparison. Its classification is the four-way Table I decision in Thompson et al. (2020), also identified as step 6 of Sec. II.A. Equality \(f_{\rm tide}=f_{\rm RD}\) belongs to the \(f_{\rm tide}\ge f_{\rm RD}\) side; only a strictly positive torus ratio has a torus remnant. The scalar reference uses the printed inequalities directly, without source or binary output from LAL.

The scalar-only precision and boundary checks passed locally (5/5). On len, the command JAX_ENABLE_X64=1 PYTHONPATH=src /home/xangma/repos/diffgw-worktrees/xas-whole-waveform-gate/.venv/bin/python -m pytest -q -s tests/test_nsbh_branch_reference.py tests/test_nsbh_torus_reference.py tests/test_nsbh_disruption_reference.py tests/parity/test_nsbh_parity.py ran from /home/xangma/tmp/diffgw-nsbh-branch-20260927 on Linux x86-64 CPU FP64. It passed 71/71 in 69.24 s with no skips or expected failures; the log is pytest.log in that directory. The new gate tests all nine exact and nextafter boundary combinations in each backend, then composes the existing independent disruption and torus references over 60 physical inputs and three controlled \(f_{\rm RD}/f_{\rm tide}\) ratios each. All four classes occur. Native Torch and JAX predicates agree exactly with the scalar decisions on every frozen case; the gate has no numerical tolerance.

The neighboring torus gate in the same run reports maximum raw torus-ratio absolute error \(5.329\times10^{-15}\) and clipped error \(2.776\times10^{-16}\) in each backend. The disruption gate reports maximum relative tidal-frequency error \(1.069\times10^{-15}\) (Torch) and \(9.897\times10^{-16}\) (JAX). These gates support the composed branch inputs; they do not validate a remnant-derived \(f_{\rm RD}\).

Environment: Python 3.12.3, Torch 2.14.0+cpu, JAX 0.11.2, NumPy 2.5.3, mpmath 1.3.0, pytest 9.1.1. This result qualifies the discrete merger-class selection in the native amplitude path. The remnant/QNM provider, branch-dependent amplitude fits and windows, phase, full waveform, and external physical agreement remain separate mandatory gates.