MathBox/MathItem composition for the Q#MS2 subset: characters advance a pen,
scripts shift by the MATH table's superscript/subscript amounts at script
scale, and \frac stacks its operands around a rule at the math axis. Inline
\frac sets its operands one style down, which is TeX's rule and also what the
parent framing's Tier 3 specifies — and it is load-bearing for Q#MS10, since
full-size operands would not fit the line at all.
The height budget is now measured rather than assumed, and the round-2 review
was right to insist on that. Two things were wrong.
First, my own test derived the budget from the MATH font's metrics. Q#MS10
says the budget is the LINE BOX, whose baseline the CODE font places —
JetBrains Mono ascends 16.32 px and descends 4.80 px at 16 px inside the 22 px
line, against Latin Modern Math's 12.90/3.10. Using the wrong font made a
plain \frac{a}{b} score 0.485 and appear to fall below the floor, which would
have meant the flagship case never rendering.
Second, with the budget derived correctly, B6 holds — \frac{a}{b} scales to
0.732 — but rev 3's guessed fallback case does not. A doubly-nested fraction
scores 0.744 and still renders; the floor is not tripped until depth 3, at
0.580. Round 2 predicted precisely this surprise-pass. Worth keeping: depth 2
scores HIGHER than depth 1, because the binding constraint flips from descent
to ascent as nesting grows asymmetrically, so "deeper is always tighter" is
false.
The test therefore SEARCHES for the tripping depth instead of hardcoding it,
and fails if no depth trips the floor at all — which would mean the fallback
arm is unreachable and the floor is dead code. Acceptance 12 records the
measured table.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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