`Holds::through`'s allowance for the two routes to a length was four half
steps either side, from a derivation that said each rounding now drops a
whole step where it used to drop half of one. That overshot: three is the
floor, two fires the `Holds` assertion in `draw_at` on eleven generated
cases, and four was never measured as necessary. Tightening both ends did
not move one of the rig's twenty-five work counters, so the extra half step
was not buying any reuse either.
It cannot go to zero. The range has to contain the box a drawing was made
in, which the assertion checks, and it must not contain a box the drawing
does not hold for, which the warm-against-cold oracle checks -- and those
two only coincide where a length reached two ways is the same number. It is
not, yet; composing in `i64` and narrowing once is the queued change that
would make it so, and shrinking this allowance is how to tell whether that
worked.
Checked: fmt, clippy, 81 suite tests, 17 core unit tests, the release oracle
at 100 seeds and at 1000 seeds of depth 6, all fifteen shrinker cases at 400
seeds of depth 5, and `tabs`, `view`, `minimal`, `text`, `random` and the tab
replay byte-identical at 1920x1200 against `2bc6bdf`.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
iris-aiandClaude Opus 5
38eba543f6