Gate bounded 140 s OSWEC selected-heading quarter-step prefix

[cmccomb]

Purpose

Extend the pinned irregular OSWEC selected-heading motion gate beyond 120 s without relying on a MATLAB run that exceeds the hosted job limit. The 160 s quarter-step attempt in run 38311782322 timed out after 330 minutes before producing a quarter-step trajectory; it supplied no 160 s numerical result.

Bounded 140 s audit

• Reuse the checksum-pinned 250 s MATLAB coarse and half-step source artifact, and run only the 140 s quarter-step source case at 0.0025 s. The case input, sea, direction bank, HDF5 generation, and existing numerical limits are unchanged.
• Keep the existing unconditional 120 s MATLAB self-change and independent Python/source gates.
• At 140 s, require both MATLAB half-to-quarter-step self-change and independent Python/quarter-step differences to meet those same limits: yaw <0.0006 rad, yaw speed <0.00015 rad/s, PTO torque <20 Nm, and relative PTO work <0.001. If either fails, the check fails and the case remains open.

The 140 s boundary was selected before this quarter-step run. In the pinned 0.01-to-0.005 s MATLAB pair, yaw self-change is 0.000459 rad at 140 s and exceeds the existing yaw limit by 145 s. An independent local Python 0.0025 s run compared with the pinned MATLAB 0.005 s path through 140 s differs by 0.000315 rad yaw, 0.0000537 rad/s speed, 6.44 Nm torque, and 0.0563% PTO work. These are diagnostics; only the new quarter-step source artifact can establish the 140 s gate.

Verification

• actionlint .github/workflows/oswec-variable-yaw-250s-step-audit.yml
• .venv/bin/python -m py_compile tests/test_variable_yaw_quarter_step_audit.py
• git diff --check
• Independent local 140 s Python run completed against the pinned half-step source artifact.

No 600 s irregular-motion parity claim or badge change follows from this bounded audit. Review the MATLAB artifact and printed numerical differences before merging.