Module markdown 

Markdown sanitizer for platform-specific rendering.

LLM outputs are Markdown. Each chat platform supports a subset of CommonMark. This module converts LLM Markdown into the subset supported by a given platform, stripping or converting unsupported features:

• Tables → aligned plain text (QQ does not support table syntax)
• Task lists (- [ ]) → plain unordered lists
• HTML tags → stripped entirely
• Images (![]()) → [Image: alt] fallback text
• Horizontal rules (---) → stripped

Everything else (headings, bold, italic, code, links, lists, blockquotes, strikethrough) is passed through as-is. Parsing uses pulldown-cmark (already in the workspace) for safe event-driven handling, so unsupported syntax inside code blocks is preserved verbatim.

Functions

prepare_markdown_for_platform

Prepare Markdown for a platform — pass through supported syntax, strip/convert unsupported.