Owner report: floor openings (stairs down) briefly covered by outside
terrain at camera in/out crossings - the historic #119 family
transition arm. Root cause: at a doorway graze the camera collision
sweep can transiently fail; retail total-failure fallback
set_viewer(&player->m_position, 1) (update_viewer @0x00453fad, and the
cell==0 bail @0x00453d1d) copies the WHOLE player Position - objcell_id
included - so retail roots those frames on the player interior cell.
Our fallback left ViewerCellId = 0, which the walk reads as an OUTDOOR
root while the eye is inside: full-screen terrain with the look-in
gates correctly refusing from the interior side - grass over the
stairwell for exactly the failing frames. The fallback now inherits
the pivot/player cell, matching retail byte-for-byte.
Suites: full Release build 0 warnings; hermetic 6,758/0.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>