fix(app): render \[...\] LaTeX display math delimiters

[simonechecchia]

Issue for this PR

Closes #24426

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Model output often uses \(...\) / \[...\] for LaTeX math instead of $...$ / $$...$$. Inline \(...\) was already handled by the existing katex tokenizer, but \[...\] was not, so it fell through to CommonMark's backslash-escape rule (which strips \[ and \] to plain [/]) and rendered as mangled text instead of math.

I added a \[...\] block-math path alongside the existing $$...$$ one, in both places math is currently handled:

• the marked tokenizer extension (blockKatex), used for the main JS render path
• the native-parser HTML post-processing fallback (renderMathInText)

Code fences and inline code spans are left untouched in both paths (verified in tests).

How did you verify your code works?

Added unit tests in packages/ui/src/context/marked.test.ts covering:

• inline \(...\) and display \[...\] / $$...$$ math on both render paths
• fenced code blocks containing \[...\]-like text are not touched
• a markdown table with math in cells (the exact shape that triggers CommonMark's backslash-escape stripping)

Ran bun test (all passing) and bun run typecheck (clean) in packages/ui.

Screenshots / recordings

Not a UI change (no new components/styles), just extends the existing katex delimiter handling in packages/ui/src/context/marked.tsx.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Related PR Found

PR #34642: fix(ui): fallback math rendering for multiline $$ blocks

• fix(ui): fallback math rendering for multiline $$ blocks #34642

Why it's related: This PR addresses similar math rendering issues. PR #35951 (current) adds support for \[...\] display math delimiters alongside the existing $$...$$ path. PR #34642 appears to handle fallback math rendering for $$ blocks. Both PRs are improving LaTeX math rendering in the app's UI, specifically in the marked tokenizer and HTML post-processing. You should verify whether #34642 already addresses the \[...\] case or if it's complementary work.

[github-actions]

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[Copilot]

Pull request overview

This PR fixes LaTeX display-math rendering for \[...\] delimiters in the UI markdown pipeline, aligning with common model output conventions and preventing CommonMark backslash-escape from mangling intended math blocks.

Changes:

• Extend math rendering to treat \[...\] as display math alongside existing $$...$$ support.
• Update the Marked tokenizer extension to recognize \[...\] as a block KaTeX token.
• Add unit tests covering both render paths, code-fence non-interference, and the reported issue repro.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/ui/src/context/marked.tsx	Adds \[...\] display-math handling in both the HTML post-processing renderer and the Marked block tokenizer path.
packages/ui/src/context/marked.test.ts	Adds coverage for inline + display math across both parsing paths, including code-fence safety and issue repro.

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