Font, licence, and the metrics half of Tier 3.
The bundled font is Latin Modern Math under the GUST Font License, added as
fonts/GUST-FONT-LICENSE.txt — deliberately a separate file from fonts/OFL.txt,
which covers JetBrains Mono only. GFL is LPPL-derived, not the SIL OFL; the
framing's F6 corrected that error and this is the discharge. At 733,736 bytes
the font is now the largest embedded asset in the repository.
ttf-parser is declared with default-features = false and only
"opentype-layout". Verified differentially: the ttf-parser feature set from
`cargo tree -e features` is byte-identical with and without this dependency
line, so the declaration widens nothing and forces no rebuild of the font
chain.
That check also corrected acceptance 17, which asserted `std` would be absent.
It is not — fontdb already enables it via `std = ["ttf-parser/std"]`, upstream
and independent of us. As written the criterion would have failed a correct
implementation, so it is now stated as the differential property that actually
matters.
MathConstants reads only what the Q#MS2 subset needs — axis height, script
scale percent, the two script shifts, and fraction rule thickness. Reading
more would be speculative: constants for deferred constructs have no consumer
to validate them, which is the Q#LX5 discipline applied to metrics. A font
with no MATH table is a typed error rather than plausible-looking zeros, so a
bundled-font regression cannot be silent (Q#MS7).
math_italic implements TeX's convention as the framing's table states it:
ASCII letters and lowercase Greek italic, uppercase Greek upright, digits and
operators unchanged, with U+210E for `h` because the 1D4xx run has a hole
there and arithmetic would land on a reserved codepoint.
Five tests, all against the real embedded bytes rather than fixtures, since B5
is the bet that would sink Tier 3 if false. One goes beyond the framing: every
italic mapping must resolve to a glyph the bundled font actually has, because
a mapping that produced tofu would be worse than the roman fallback it
replaces.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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