Add spell checker page

[simonw]

Summary

• add spellcheck.html with a Claude-based spell checker UI
• document the new page in spellcheck.docs.md

Testing

• pytest -q (fails: ModuleNotFoundError: No module named 'playwright')

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https://chatgpt.com/codex/tasks/task_e_6872f31ed2348326bc439d5f99ba1e35

[cloudflare-workers-and-pages]

Deploying tools with    Cloudflare Pages

Latest commit:	703ab01
Status:	✅  Deploy successful!
Preview URL:	https://a30c00ab.tools-b1q.pages.dev
Branch Preview URL:	https://codex-build-spellcheck-html.tools-b1q.pages.dev

View logs

[claude]

Claude finished @simonw's task —— View job

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Code Review Completed ✅

I've thoroughly reviewed the spell checker implementation. Overall, this is a well-structured and functional tool, but there are several important security and quality concerns that should be addressed.

Review Tasks

• Read and analyze spellcheck.html
• Read and analyze spellcheck.docs.md
• Review code quality and best practices
• Check for potential bugs and issues
• Assess security concerns
• Evaluate performance considerations
• Review test coverage needs
• Provide comprehensive review feedback

🚨 Critical Security Issues

1. API Key Storage (spellcheck.html:117-126)

Issue: API keys stored in localStorage are accessible to any script and persist across sessions.
Risk: High - API key exposure to malicious scripts or browser inspection
Recommendation: Consider server-side proxy or environment variables for API key management

2. XSS Vulnerability (spellcheck.html:250-251)

Issue: User input directly inserted into innerHTML without sanitization:

errorDiv.innerHTML = `<strong>"${error.word_to_replace}"</strong> → <strong style="color: #4CAF50;">"${error.replacement_string}"</strong>`

Risk: High - Potential script injection if Claude API returns malicious content
Recommendation: Use textContent or proper HTML escaping

3. Client-Side API Exposure (spellcheck.html:193-206)

Issue: API calls made directly from client-side expose implementation details
Risk: Medium - API key visible in network requests, rate limiting bypassed
Recommendation: Implement server-side proxy endpoint

🐛 Potential Bugs & Issues

1. Regex Word Boundary Matching (spellcheck.html:278-279)

Issue: Simple find/replace may not handle punctuation and capitalization edge cases properly
Example: "Hello," vs "hello" replacement scenarios
Recommendation: Enhanced word boundary detection with context awareness

2. Memory Leak (spellcheck.html:111)

Issue: MutationObserver never disconnected, could accumulate over time
Recommendation: Add cleanup method and disconnect observer when appropriate

3. DOM Assumptions (spellcheck.html:88)

Issue: Assumes textarea.parentNode and nextSibling exist without validation
Recommendation: Add null checks before DOM manipulation

⚡ Performance Considerations

1. API Call Efficiency

• Each spell check triggers full API call (potentially expensive)
• Consider debouncing for real-time checking
• Implement caching for repeated text

2. MutationObserver Overhead (spellcheck.html:95-111)

• Observes all DOM changes, could be intensive on dynamic pages
• Consider more targeted observation or lazy initialization

🧪 Test Coverage

Missing Tests

• No automated tests for JavaScript functionality
• No API response mocking
• No edge case testing (empty text, malformed responses, API errors)
• The mentioned pytest failure suggests testing infrastructure exists but isn't utilized

Recommendation: Add Playwright/Jest tests for:

• UI interactions (button clicks, text input)
• API error handling
• DOM manipulation edge cases
• Security scenarios

👍 Code Quality Highlights

• Clean Architecture: Well-structured class-based design with clear separation of concerns
• Modern JavaScript: Good use of async/await, template literals, and modern DOM APIs
• Error Handling: Comprehensive try/catch blocks with user-friendly error messages
• User Experience: Intuitive UI with loading states and one-click fixes
• Dynamic Content Support: MutationObserver handles dynamically added textareas

📝 Minor Improvements

1. Documentation: Add JSDoc comments for better maintainability
2. Configuration: Make model name and API parameters configurable
3. Constants: Extract magic numbers (max_tokens: 1000) to named constants
4. Progressive Enhancement: Add fallback behavior for JavaScript-disabled environments

🏆 Overall Assessment

This is a functional and user-friendly spell checker implementation with good code structure. However, the security vulnerabilities (especially XSS and API key storage) should be addressed before production use. The core functionality is solid and the UI/UX is well-designed.

Recommendation: Address security issues first, then consider performance optimizations and test coverage improvements.

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