Unit 5 filtered on height, so a collapsed quad would have been invisible to
it by construction. Dropping that filter: across the whole title era,
frames >=700, every quad regardless of size --
RIGHT->LEFT travellers (pteff03a's direction): 0
LEFT->RIGHT travellers: 2 (both pteff03)
static shapes: 10
degenerate/collapsed quads: 0
Not one quad travels right-to-left in the entire title era at any size, and
nothing is submitted collapsed. So pteff03a is absent from the draw stream
-- not drawn invisibly, not drawn at zero scale. That strengthens unit 5
from "no tall quad of that size" to "no quad of that motion at all".
All three candidate mechanisms are now dead: the zero-alpha skip is weak on
its own terms (explains opening frames, not a whole run), the focus/variant
link was eliminated by the port's wider survey (linked targets chain across
unrelated element kinds -- on one menu a sweep points at a button, so the
field is a chain pointer rather than a variant selector), and collapsed
scale dies here.
Recording that as the state rather than proposing a fourth candidate.
Three have been named and three have failed, two by checks that took
minutes. A fourth guess before the human's "one streak or two" look would
be guessing against an answer about to arrive for free.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
d53128151f