`$\sqrt[3]{8}$` renders as a plain square root — the index is gone. It is
not a KaTeX layout problem: the index never reaches KaTeX. CITATION_MARKER_RE
strips `[3]` as a citation marker, because its lookbehind accepts any letter
and the `t` of `\sqrt` qualifies. That runs inside normalizeVisibleProse,
which splits out inline code spans but not math, so TeX is fed to rewrites
written for prose.
Numeric-only, which is why `\sqrt[n]{8}` survives and made this look like a
layout edge case rather than a preprocessing one.
Shield math the same way inline code is already shielded: split each prose
part on math spans and rewrite only the segments between them. That also
takes math out of the reach of the other rewrites in that pass
(autoLinkRawUrls, LOCAL_PREVIEW_URL_RE, the ``` stripper, linkifySessionRefs),
any of which can corrupt TeX the same way with different input.
The split is capturing, and math segments are identified by index parity
rather than a leading `$`, so a prose run that merely opens with a stray
dollar cannot be mistaken for math. Escaped `\$` delimiters stay prose, which
is what keeps `$5 and $10` escaping intact.
Verified in the real renderer through the desktop mock-backend E2E harness:
`.katex .root` (the span KaTeX emits for a radical index) goes from 1 to 4 on
the same four-radical reply, and the MathML annotations show KaTeX receiving
`\sqrt[3]{8}` intact rather than `\sqrt{8}`.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SPGjEQ2yrS4nWiooUEdYti
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