fix: katex array breaking the app

[OtavioStasiak]

Proposed changes

KaTeX arrays should be rendered using our KaTeX component, not MathView.
Usually, this kind of KaTeX should go to renderError and then be rendered using the KaTeX component. However, MathView is not treating it as an error and is also unable to render it correctly. Because of that, I added a validation to detect arrayKaTeX and render it using the correct component.

Issue(s)

https://rocketchat.atlassian.net/browse/SUP-990

How to test or reproduce

• send a katex message like this and open the room:

 \\begin{array}{|c|c|c|c|c|c|} \\hline \\text{testing} & \\text{testingII} & \\text{testing III} & \\text{testing IV} & \\text{testV} & \\text{testVI} \\\\ \\hline \\text{TEST} & \\text{TEST} & \\text{TEST} & \\text{TEST} & \\text{TEST} & \\text{TEST} \\\\ \\hline\\text{TEST} & \\text{✅} & \\text{test} & \\text{test} & \\text{test} & \\text{✅} \\\\ \\hline \\end{array} 

Screenshots

Before	After

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments

Summary by CodeRabbit

• Bug Fixes

  • Improved rendering of block mathematical environments (arrays, matrices) with proper display formatting and error handling.

• Tests

  • Added test stories for array-based mathematical formula rendering scenarios.

[coderabbitai]

Walkthrough

These changes address KaTeX array rendering by introducing block environment detection in the KaTeX component, which short-circuits rendering in display mode instead of delegating through MathView. New story exports are added to demonstrate KaTeX array rendering behavior.

Changes

Cohort / File(s)	Summary
KaTeX Block Environment Detection app/containers/markdown/components/Katex.tsx	Added BLOCK_ENV_PATTERN regex to identify block environments (array, matrix, pmatrix, bmatrix, Bmatrix, vmatrix, Vmatrix) and modified rendering logic to short-circuit display mode for detected blocks, bypassing MathView. Updated renderError to display block KaTeX in display mode consistently.
Story Exports app/containers/message/Message.stories.tsx	Introduced KatexArray and KatexArrayLargeFont story exports with corresponding katexArray payload structure to demonstrate array-based KaTeX rendering.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix: katex breaking the app #6710: Both PRs modify KaTeX-related message stories in app/containers/message/Message.stories.tsx by adding new KaTeX story exports for testing different KaTeX rendering scenarios.

Suggested reviewers

• diegolmello

Poem

🐰✨ A hop through matrices and arrays so fine,
Block patterns gleaming in display design,
No black squares now—just beauty in sight,
KaTeX arrays rendering perfectly right! 📐

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately identifies the main fix: routing KaTeX array rendering to the correct component to prevent app breakage.
Linked Issues check	✅ Passed	The PR implements the required fix for SUP-990 by detecting array-style KaTeX and routing it to the KaTeX component, preventing rendering failures and app breakage.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the KaTeX array rendering issue: pattern detection, component routing, and story examples demonstrating the fix.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix.katex-array-breaking-the-app

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[Rohit3523]

LGTM