An art edge with no Riot line alongside used to take the nearest line within
2 units, so a ring or box touching a wall took the wall's line where it came
near. An agent just inside Split's ring by the B wall got a cone cut into
slivers. Now only a short stretch (at most 4 units) between walled edges
borrows the nearest line: a bevel, a jog, a wall's end. A test pins the
Split ring; it fails on the previous models.

The 3D check in the doc now counts only what lands on floor the app draws.
Rays leaving the map were counted before, which made Pearl look worse than it
is. Walling the void was tried and dropped: it blocked real sightlines
across drops on Abyss and Icebox.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>