mcpbeat

Mdx Sanitizer

curiositech/mdx-sanitizer

Sanitize MDX content for Docusaurus builds. Fixes unescaped angle brackets (<, >, &lt;=, &gt;=), Liquid/Nunjucks template syntax ({{ }}), TypeScript generics (Promise&lt;T&gt;), and inline code backtick edge cases. Use when pre-commit hooks fail on bracket or Liquid validation, or when MDX/JSX build errors reference unexpected tokens. NOT for general markdown linting or prose editing.

1k tokens
context cost
the whole folder, loaded on every use
1
files
instructions only
0
copies elsewhere
how many repositories repackaged it
177
stars on the repo
on the repository, not the skill itself

Install

one command, takes just this skill from the repository 
npx skills add https://github.com/curiositech/some_claude_skills --skill mdx-sanitizer

The instruction itself

18 sections, as written by the author

MDX Sanitizer

Comprehensive MDX content sanitizer that prevents JSX parsing errors caused by angle brackets, generics, and other conflicting patterns.

The Problem

MDX 2.x treats unescaped < and { as JSX syntax. This causes build failures when content contains:

  • TypeScript generics: Promise&lt;T&gt;, Array&lt;string&gt;, Map&lt;K, V&gt;
  • Comparisons: &lt;100ms, &lt;=, &gt;=
  • Arrows: --&gt;, &lt;--, -&gt;
  • Invalid tags: &lt;link&gt; in prose, &lt;tag&gt; placeholders
  • Empty brackets: &lt;&gt;

Solution Architecture

This skill implements a three-layer defense:

1. Sync-Time Sanitization (Proactive)

Content is sanitized when syncing from .claude/skills/ to website/docs/:

  • syncSkillDocs.ts - Main skill files
  • syncSkillSubpages.ts - Reference files
  • doc-generator.ts - Generated docs

2. Pre-Commit Validation (Reactive)

The git pre-commit hook validates files before commit using validate-brackets.js.

3. Build-Time Validation (Final Check)

npm run validate:all runs as part of prebuild to catch any issues.

Usage

Check for Issues (Dry Run)

cd website
npm run sanitize:mdx
# or with verbose output
npm run sanitize:mdx -- --verbose

Fix All Issues

cd website
npm run sanitize:mdx -- --fix
# or shorthand
npm run fix:mdx

Programmatic API

import { sanitizeForMdx, validateMdxSafety, isMdxSafe } from './lib/mdx-sanitizer';

// Sanitize content
const result = sanitizeForMdx(content, { useHtmlEntities: true });
if (result.modified) {
  console.log(`Fixed ${result.issues.length} issues`);
  fs.writeFileSync(path, result.content);
}

// Validate without modifying
const issues = validateMdxSafety(content, 'path/to/file.md');

// Quick check
if (!isMdxSafe(content)) {
  // Handle issues
}

Escaping Strategies

The sanitizer uses HTML entities for maximum compatibility:

| Pattern | Original | Escaped |

|---------|----------|---------|

| Less-than | < | &lt; |

| Greater-than | > | &gt; |

| Generics | &lt;T&gt; | &amp;lt;T&amp;gt; |

| Comparison | &lt;= | &amp;lt;= |

Content inside code blocks ( or ) is automatically protected and never escaped.

Files Modified

  • website/scripts/lib/mdx-sanitizer.ts - Core sanitizer module
  • website/scripts/sanitize-mdx.ts - CLI wrapper
  • website/scripts/syncSkillDocs.ts - Integration
  • website/scripts/syncSkillSubpages.ts - Integration
  • website/scripts/lib/doc-generator.ts - Integration
  • website/package.json - npm scripts

Patterns Detected

  • Less-than before digit: &lt;100, &lt;0.5ms
  • Comparison operators: &lt;=, &gt;=
  • Empty brackets: &lt;&gt;
  • Arrows: &lt;--, --&gt;
  • Generic types: Promise&lt;T&gt;, Array&lt;string&gt;
  • Space after less-than: &lt; value
  • Invalid pseudo-tags: &lt;link&gt;, &lt;tag&gt; (not valid HTML)

Troubleshooting

Build Still Fails After Running Sanitizer

  • Clear Docusaurus cache: npm run clear
  • Re-run sanitizer: npm run sanitize:mdx -- --fix
  • Rebuild: npm run build

False Positives

If valid JSX components are being escaped:

  • Ensure they use PascalCase (e.g., &lt;MyComponent&gt;)
  • Check they're valid HTML5 elements

Manual Escaping

For edge cases, manually escape in source:

  • Use backticks for inline code: &lt;T&gt;
  • Use fenced code blocks for multi-line
  • Use HTML entities: &lt; and &gt;

Sources

How to use it

Copy the folder

Take curiositech/mdx-sanitizer from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.