mdx-sanitizer

name: mdx-sanitizer description: Sanitize MDX content for Docusaurus builds. Fixes unescaped angle brackets (<, >, <=, >=), Liquid/Nunjucks template syntax ({{ }}), TypeScript generics (Promise<T>), 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. allowed-tools:

Read
Write
Edit
Bash
Glob
Grep version: 1.0.0 triggers:
mdx error
angle bracket
jsx parsing
build failure mdx
escape angle brackets
sanitize markdown metadata: category: DevOps & Automation tags:
- mdx
- docusaurus
- markdown
- build-tools
- sanitization pairs-with:
- skill: site-reliability-engineer reason: MDX build failures are a primary Docusaurus deployment blocker that SRE validates
- skill: technical-writer reason: Technical writers produce the MDX content that needs sanitization for safe rendering
- skill: skill-documentarian reason: Skill documentation in MDX format requires sanitization before website deployment

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<T>, Array<string>, Map<K, V>
Comparisons: <100ms, <=, >=
Arrows: -->, <--, ->
Invalid tags: <link> in prose, <tag> placeholders
Empty brackets: <>

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	`<`	`<`
Greater-than	`>`	`>`
Generics	`<T>`	`&lt;T&gt;`
Comparison	`<=`	`&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: <100, <0.5ms
Comparison operators: <=, >=
Empty brackets: <>
Arrows: <--, -->
Generic types: Promise<T>, Array<string>
Space after less-than: < value
Invalid pseudo-tags: <link>, <tag> (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., <MyComponent>)
Check they're valid HTML5 elements

Manual Escaping

For edge cases, manually escape in source:

Use backticks for inline code: `<T>`
Use fenced code blocks for multi-line
Use HTML entities: < and >