Review finding, verified: rev 2's "no new build cost" was true only under
an unstated condition. ttf-parser re-exports `math` behind
`#[cfg(feature = "opentype-layout")]`, and it is compiled today only
because fontdb requests that feature — with `default-features = false` and
a set that is NOT ttf-parser's own default (fontdb's adds no-std-float and
omits std). A plain `ttf-parser = "0.25"` therefore unions std in and
forces a one-time rebuild of ttf-parser, fontdb, cosmic-text and glyphon.
Record the zero-rebuild spelling, `default-features = false, features =
["opentype-layout"]`, in Tier 3 §A and in the component table, so the
Tier 3 implementer declares it deliberately rather than tripping over it.
The C1 row points at the detail rather than repeating it.
Also note in the header that every anchor was re-checked at f07b75b. The
scout pin stays at ddaa80d because that is when the scouting happened;
#153 landed between the two and is test-only, moving no anchor cited here.
Framing only; no implementation, no runtime code.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Revision 1 was written against protocol v18, before LaTeX Stage 1 (#144),
web grammars (#146), folding Stages 1-2 (#142/#149) and the GPU initial
target (#148) landed. Revision 2 changes no design decision; it corrects
the ground truth those merges invalidated and records the staging decision
the sibling substrate framing already took. A new section 0 lists every
correction so a reader who knows revision 1 can read it alone.
Two corrections change implementation choices rather than line numbers:
- The MATH-table dependency story was wrong in both directions. Revision 1
said a crate must be added and that "neither is in the tree today";
ttf-parser 0.25.1 already reaches pmacs-gpu non-optionally through
fontdb -> cosmic-text -> glyphon, the same fontdb the frontend already
calls. And the choice is not "one of ttf-parser or read-fonts": only
ttf-parser exposes the MATH table, supplying exactly the constants Tier
3 names. read-fonts 0.37.0 is present but has none, so selecting it
would be a dead end.
- Tier 2's staging was already decided elsewhere and this note did not say
so. The sibling framing's Q#LX5 puts the parser beside its Tier 3
consumer, never ahead of it, because MathNode's shape is only validated
by a layout consumer. That makes Tier 2 not independently shippable,
which is worth stating explicitly: it is pure and conflict-free, so
landing it alone while other lanes hold the render path is exactly the
tempting move Q#LX5 refused.
Tier 1 is materially de-risked: the LaTeX grammar already exposes
math_environment and math_delimiter, and the in-repo query overlay this
tier proposed already exists and captures both, so the mechanism is proven
rather than speculative. The guessed node name (math_expression) is
corrected to the grammar's own. Markdown still needs the overlay
treatment.
Tier 4 gains a contention note. Revision 1 described the GPU render path
as though math were its only claimant; folding Stage 3 and the
bottom-panel arc's Stage 2 now converge on it, so whichever lands second
re-scouts against the first.
Framing only; no implementation, no runtime code.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The parent-arc framing was authored on the desktop but never tracked, so
references to it — from the merged latex-grammar lane framing and its Cargo.toml
comment (#144) — dangled on a fresh clone. Commit it as its own docs change and
drop the now-stale "untracked, desktop-only" caveat from the lane framing.
Frames the full four-tier inline-math renderer (detection -> parse -> layout ->
GPU render). Stage 1 (LaTeX grammar) shipped as #144; the math parser (Tier 2),
layout (Tier 3), GPU render (Tier 4), and (math_environment) @math injection are
deferred, tracked in docs/latex-grammar-math-substrate-framing.md.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Levi Neuwirth