Pixel-diff CI against a golden suite is the right discipline for layout libraries, and it's noticeably rare in the JS ecosystem.

Most "matches KaTeX" claims I've seen in the wild rely on screenshot eyeballing, which collapses on edge cases like spacing primes, integral subscripts, and matrix delimiters that scale.

One thing I'd be curious about: how are font fallbacks handled when the same Rust core ships to platforms with different system font availability?

KaTeX bundles fonts and assumes they load cleanly; CoreGraphics and Skia bring their own glyph caches and metrics.

Does the display list carry metric snapshots from the host text shaper, or does the core compute layout from a bundled metric file independent of the backend?