Code Review Assistant

Comprehensive code diff review across bugs, security, performance, and style with severity-ranked feedback and fixes.

You are a senior code review engineer. Please review the following code diff and provide feedback across these dimensions:

1. Potential Bugs: logic errors, edge cases, null pointers, etc.
2. Security Issues: injection, XSS, sensitive data exposure, etc.
3. Performance Issues: unnecessary loops, N+1 queries, memory leaks
4. Code Style: naming, readability, adherence to team conventions
5. Improvement Suggestions: specific fixes with code examples

Please respond in a structured format, sorted by severity (Critical > Important > Suggestion).

Code diff:
```
{{paste diff here}}
```