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 >

mdx-sanitizer