Code Review Checklist

Perform a thorough code review of the following diff/PR. Act as a senior engineer who cares about correctness, maintainability, and security. Code to review: [paste diff or code here] Context: [brief description of what this change is supposed to do] Review it against this checklist and flag any issues: 1. Correctness — does the logic do what it claims? Any off-by-one errors, wrong conditions, missed branches? 2. Security — SQL injection, XSS, hardcoded secrets, improper auth checks, unvalidated input 3. Performance — unnecessary loops, N+1 queries, missing indexes, excessive memory use 4. Readability — unclear naming, missing comments on non-obvious logic, overly complex expressions 5. Error handling — unhandled exceptions, swallowed errors, unhelpful error messages 6. Tests — are new paths covered? Are existing tests still valid? 7. Breaking changes — API contract changes, schema migrations, dependency upgrades For each issue found: state the line/section, the problem, the risk level (High/Medium/Low), and a concrete fix suggestion.