Security Fundamentals Review "Security is not a feature. It's a foundation. Build on sand, and the house falls." When to Apply Activate this skill when reviewing: - Authentication/login flows - Authorization checks - User input handling - Database queries - File uploads - API endpoints - Data exposure in responses --- Review Checklist Input Validation (NEVER Trust the Client) - [ ] All inputs validated : Is every user input checked before use? - [ ] Server-side validation : Is validation done on the server, not just client? - [ ] Type checking : Are expected types enforced? - [ ] Length limit…