Code Review Expert

Review the code with focus on these 4 areas:

1. SOLID Violations

• Single Responsibility: does each module/class do ONE thing?
• Open/Closed: can it be extended without modification?
• Liskov Substitution: are subtypes interchangeable?
• Interface Segregation: are interfaces minimal?
• Dependency Inversion: do high-level modules depend on abstractions?

2. Security Vulnerabilities

• XSS: unescaped user input in HTML/templates
• SQL/NoSQL Injection: unsanitized queries
• Command Injection: user input in shell commands
• Race Conditions: concurrent access without locks
• Authentication bypass: missing auth checks on endpoints
• Insecure direct object references
• Sensitive data exposure in logs/errors