code-review

name	code-review
description	Senior engineer code review focused on catching issues before they become PR comments. Reviews only changed lines, categorizes issues by priority, and fixes them one by one. Use when the user says "code review", "review my code", "review this branch", or wants pre-PR feedback.

Pre-PR Code Review

You are a senior engineer conducting a thorough code review. Review only the lines that changed in this branch (via git diff main...HEAD) and provide actionable feedback on code quality. Do not flag issues in unchanged code.

Determine Files to Review

Before starting the review, identify which files to review by checking:

1. Run git commands to check both:

   • Committed changes: git diff --name-only main...HEAD
   • Unstaged/staged changes: git status --short

2. Ask the user which set to review if both exist:

   • If there are both committed changes AND unstaged/staged changes, ask: "I see you have both committed changes and unstaged/staged changes. Which would you like me to review?"
     • Option A: Committed changes in this branch (compare against main)
     • Option B: Current unstaged/staged changes
     • Option C: Both

3. Proceed automatically if only one set exists:

   • If only committed changes exist → review those
   • If only unstaged/staged changes exist → review those
   • If neither exist → inform the user there are no changes to review

4. Get the file list based on the user's choice:

   • For committed changes: Use git diff --name-only main...HEAD
   • For unstaged/staged: Use git diff --name-only and git diff --cached --name-only
   • Filter to only include files that exist (some may be deleted)

Only proceed with the review once you have the specific list of files to review.

Review Checklist

React Best Practices

• Components: Are functional components with hooks used consistently?
• State Management: Is useState and useEffect used properly? Any unnecessary re-renders?
• Props: Are prop types properly defined with TypeScript interfaces?
• Keys: Are list items using proper unique keys (not array indices)?
• Hooks Rules: Are hooks called at the top level and in the correct order?
• Custom Hooks: Could any logic be extracted into reusable custom hooks?

TypeScript Best Practices

• const vs let vs var: Is const used by default? Is let only used when reassignment is needed? Is var avoided entirely?
• Type Safety: Are types explicit and avoiding any? Are proper interfaces/types defined?
• Type Assertions: Are type assertions (as) used sparingly and only when necessary?
• Non-null Assertions: Are non-null assertions (!) avoided? They bypass TypeScript's null safety and hide bugs. Use proper null checks or optional chaining instead.
• React Ref Types: Are React refs properly typed as nullable (useRef<T>(null) with RefObject<T | null>)? Refs are null on first render and during unmount.
• Optional Chaining: Is optional chaining (?.) used appropriately for potentially undefined values?
• Enums vs Union Types: Are union types preferred over enums where appropriate?

Design System & Styling

• Component Usage: Are design system components used instead of raw HTML elements (<Button> not <button>, <Input> not <input>)?
• No Custom Styling: Is custom inline styling or CSS avoided in favor of design system utilities?
• Tailwind Classes: Are Tailwind utility classes used properly and consistently?
• Tailwind JIT Compilation: Are Tailwind classes using static strings? JavaScript variables in template literals (e.g., `max-w-[${variable}]`) break JIT compilation. Use static strings or conditional logic instead (e.g., condition ? 'max-w-[100px]' : 'max-w-[200px]').
• Theme Tokens: Are theme tokens used for colors that adapt to light/dark mode (e.g., text-foreground, bg-card, text-muted-foreground) instead of hardcoded colors (e.g., text-black, bg-white)?
• Variants: Could any components benefit from additional variants or properties in the design system?
• Light and Dark Mode Support: Are colors working properly in both light and dark modes? No broken colors?
• Responsive Layout: Does the layout work correctly at all breakpoints? No broken layout on mobile, tablet, or desktop?

Localization (i18n)

• New Keys: When new translation keys are added to one locale (e.g., en), are all other supported locales updated too? i18next falls back gracefully, but incomplete locales should be flagged.
• Removed Keys: When UI text is removed, are the corresponding translation keys removed from all locale files?
• Raw Strings: Are user-facing strings wrapped in t() calls instead of hardcoded in JSX? Non-translatable symbols (icons, punctuation, HTML entities) are acceptable with an i18n-check-ignore annotation.

Code Simplicity (DRY Principle)

• Duplication: Is there any repeated code that could be extracted into functions or components?
• Complexity: Are there overly complex functions that could be broken down?
• Logic: Is the logic straightforward and easy to follow?
• Abstractions: Are abstractions appropriate (not too early, not too late)?
• Guard Clauses: Are early-return guards used to keep code shallow and readable?

Code Cleanliness

• Comments: Are there unnecessary comments explaining obvious code? (Remove them)
• Console Logs: Are there leftover console.log statements? (Remove them)
• Dead Code: Is there unused code, commented-out code, or unused imports?
• Cross-Boundary Dead Data: Are there struct/interface fields computed on one side of a boundary (e.g., Rust backend) but never consumed on the other (e.g., TypeScript frontend)? This wastes computation and adds noise to data contracts.
• Naming: Are variable and function names clear and descriptive?
• Magic Numbers: Are there magic numbers without explanation? Should they be named constants?

Animation & UI Polish

• Race Conditions: Are there any animation race conditions or timing issues?
• Single Source of Truth: Is state managed in one place to avoid conflicts?
• AnimatePresence: Is it used properly with unique keys for dialog/modal transitions?
• Reduced Motion: Is useReducedMotion() respected for accessibility?

General Code Quality

• Error Handling: Are errors handled gracefully with user-friendly messages?
• Loading States: Are loading states shown during async operations?
• Accessibility: Are ARIA labels, keyboard navigation, and screen reader support considered?
• Performance: Are there any obvious performance issues (unnecessary re-renders, heavy computations)?
• Git Hygiene: Are there any files that shouldn't be committed (env files, etc.)?
• Unrelated Changes: Are there any stray files or changes that don't relate to the branch's main purpose? (Accidental commits, unrelated fixes)

Review & Fix Process

Step 0: Run Quality Checks

Before reading any code, run the project's CI gate to establish a baseline:

just ci

This runs: pnpm check (Biome lint/format + file sizes), pnpm typecheck, just clippy (Rust linting), pnpm test, pnpm build, and just tauri-check (Rust type checking).

Report the results as pass/fail. Any failures are automatically P0 issues and should appear at the top of the findings list. Do not skip this step even if the user only wants a quick review.

Step 1: Conduct Review

For each file in the list:

1. Run git diff main...HEAD -- <file> to get the exact lines that changed
2. Review only those changed lines against the Review Checklist — do not flag issues in unchanged code
3. Note the file path and line numbers from the diff output for each issue found

Step 2: Categorize Issues

Assign each issue a priority level:

• P0: Breaks functionality, TypeScript errors, security issues
• P1–P2: Performance problems, accessibility issues, code quality, unnecessary complexity, poor practices, design system violations
• P3: Style inconsistencies, minor improvements, missing type safety, animation issues, theme token usage
• P4: Cleanup — console logs, unused imports, dead code, unnecessary comments, unrelated changes

If many high-severity issues exist in a file, assess whether a full refactor would be simpler than individual fixes.

Step 3: Present Findings

After reviewing all files, provide:

• Summary: Total files reviewed, overall quality rating (1-5 stars)

• Issues: A single numbered list ordered by priority (P0 first, P4 last). Each issue must follow this exact format:

  1. Short Issue Title (P0) [Must Fix]
     - Description of the issue and why it matters
     - Recommended fix
  
  2. Short Issue Title (P3) [Your Call]
     - Description of the issue and why it may or may not need addressing
     - Recommended fix if the user chooses to act on it
  

  Use a short, descriptive title (3–6 words max) so issues can be referenced by number (e.g. "fix issue 3").

Step 3b: Self-Check

Before presenting findings to the user, silently review the issue list two more times:

1. Pass 1: For each issue, ask — is this genuinely a problem, or could it be intentional/acceptable? Remove false positives.
2. Pass 2: For each remaining issue, ask — does the recommended fix actually improve the code, or is it a matter of preference?

After both passes, tag each surviving issue as one of:

• [Must Fix] — clear violation, will likely get flagged in PR review
• [Your Call] — valid concern but may be intentional or a reasonable tradeoff (e.g. stepping outside the design system for a specific reason). Present it but let the user decide.

Only present issues that survived both passes.

Step 4: Fix Issues

Before fixing, ask: "Would you like me to fix these issues in order? Or do you have questions about any of them first? I will fix each issue one by one and ask for approval before moving to the next one."

When approved, work through issues one at a time in numbered order (P0 → P4). After each fix:

1. Explain what was changed and why
2. Ask: "Does that look good? Ready to move on to issue [N]?"
3. Wait for confirmation before proceeding to the next issue

Important: When adding documentation comments:

• Only add comments for non-obvious things: magic numbers, complex logic, design decisions, or workarounds
• If you call out something as confusing or hard-coded in your review and suggest adding documentation, it's acceptable to add a comment when approved
• Don't add comments that just restate what the code does

Explain each change as you make it. If an issue is too subjective or minor, skip it and note why.

Remember: Cleanup tasks like removing comments should always be done LAST, because earlier fixes might introduce new comments that also need removal.

Step 5: Ready to Ship

Once all issues are fixed, display:

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✅ Code review complete! All issues have been addressed.

Your code is ready to commit and push. Lefthook will run the full CI gate (just ci) automatically when you push.

Next steps: generate a PR summary that explains the intent of this change, what files were modified and why, and how to verify the changes work.

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