F1 was a real bug pinned by my own committed test. `end` in
ChunkSource::MathBox is EXCLUSIVE, so source position `end` is the first byte
AFTER the span — but the arm claimed it for the box's left edge, and the test
asserted that wrong value while calling the byte "interior". Consequences it
would have caused once overlays land: a search match starting just after a
span washes the whole box it does not intersect, violating Q#MS11; a peer
caret after the span draws at the box's left edge; caret geometry jumps
backwards. The same class existed in projected_to_source for a line-FINAL box,
where `within` clamps to the run length and the arm returned `start`
unconditionally, so a click past end-of-line landed on the span start. Both
committed hit tests put a chunk after the box, so that edge was never
exercised; there is now a test with the box last.
F2: parse_scripts peeked for the next marker without skipping whitespace, so
`x^2 _i` built a NESTED script — drawing the subscript displaced right by the
superscript's width — and `x^2 ^3` parsed where TeX errors, contradicting the
module's own "whitespace is insignificant" rule.
F3: layout is now fallible. A character the math font cannot draw used to
yield zero metrics and still emit a Glyph item, rendering tofu at zero advance
over its neighbour. Q#MS8's rule is "failure is always show the source", and
the draw pass needs a refusal signal — changed now, before that pass consumes
the API.
F4: the fraction gap was a hardcoded `thickness * 2.0` while the MATH table's
FractionNumeratorGapMin / FractionDenominatorGapMin went unread. Reading them
moved the flagship \frac{a}{b} from 0.732 to 0.867 and the fallback boundary
from depth 3 to depth 5. The round-2 review's hand-arithmetic estimate of
~0.85 was right; my 0.732 was inflated by the guess. The depth-SEARCHING test
absorbed the change without edits, which is the property it was written for.
F5: TeX's \epsilon and \phi are the lunate/symbol forms (U+03F5, U+03D5), not
U+03B5/U+03C6. Their italic mappings had to land with the seed change, since
both sit outside math_italic's U+03B1..03C9 run and would otherwise render
upright beside italic neighbours.
F7: the line-box budget derivation moved out of the test into
`line_box_budget`, so the draw pass and the acceptance test cannot compute
different splits while both stay green.
F8: the live-code clippy items are cleared. The 25 that remain are all
dead-code awaiting the draw pass.
189 pmacs-gpu tests pass.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Levi Neuwirth
cbf7782726