Session shipped the _datLock-contention fix (lockwait 88ms->0, kept). Remaining
FPS pain (sustained ~30 in Fort Tethana, view-direction-dependent) root-caused to
the absence of distance-based LOD/degrade: we draw every frustum-visible object at
full detail. Next: port retail UpdateViewerDistance/get_degrade. Full mechanism,
file:line map, apparatus state, and DO-NOT-RETRY lessons captured.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
