openclaw - 💡(How to fix) Fix Add LaTeX math formula rendering (KaTeX) to markdown renderer

Summary

Add LaTeX/math formula rendering support to the built-in markdown renderer (e.g. via KaTeX).

Problem to solve

Many users need to write mathematical formulas in chat messages — $E=mc^2$, $$\int_0^1 x^2 dx$$, matrices, integrals, summations, etc. Currently, writing LaTeX syntax in OpenClaw messages displays as raw text with no rendering. This is a common pain point for researchers, students, and technical professionals.

Proposed solution

Integrate KaTeX (preferred over MathJax for performance) into the markdown rendering pipeline:

1. Backend (send-hHuodC8E.js): Extend the existing markdown-it instance with markdown-it-katex or equivalent math block/inline token rules, so $...$ (inline) and $$...$$ (block) expressions are rendered to HTML with proper KaTeX output.
2. Frontend (Control UI): Load KaTeX CSS/JS in index.html and ensure the frontend markdown renderer (also markdown-it based) handles math expressions consistently.

Both the sender-side (when composing) and receiver-side (when viewing) should render math identically.

Alternatives considered

Impact

• Affected users/systems/channels: All channels using markdown rendering (webchat, QQ Bot, Telegram, Feishu, etc.)
• Severity: Annoying — doesn't break functionality but forces ugly workarounds
• Frequency: Common for academic/technical users; every math-heavy conversation is affected
• Consequence: Users either give up writing math in OpenClaw, or use screenshots/external tools

Evidence / Prior art

Nearly every modern note-taking and messaging platform supports LaTeX math rendering:

• GitHub (readmes, issues) — KaTeX
• Notion — native
• Obsidian — KaTeX plugin (default in many configs)
• Typora — native
• Discord — KaTeX (via bots)
• Mattermost — KaTeX
• Stack Overflow — KaTeX

Supporting math rendering would bring OpenClaw in line with user expectations for a modern AI agent platform.

Additional context

• KaTeX is MIT licensed, lightweight (~400KB vs MathJax's ~2MB), and renders 10-100x faster.
• markdown-it ecosystem has mature KaTeX integration: markdown-it-katex, markdown-it-mathjax, or custom token rules.
• The backend already uses markdown-it (send-hHuodC8E.js line 264), so the plugin hook point is already there — only the plugin registration and KaTeX dependency are missing.
• Configuration could be a simple boolean toggle in openclaw.json:

  {
    \"markdown\": {
      \"mathRendering\": \"katex\"  // or \"off\" (default), or \"mathjax\"
    }
  }