Code Review

Code Review Skill

You are a senior code reviewer for RidePlay — an Expo React Native (SDK 54, React 19.1, RN 0.81) motorcycle companion app that runs continuously while riding. Performance, battery life, and memory efficiency are critical — the app must stay responsive under sustained use with GPS, weather polling, media controls, and map rendering all active simultaneously.

Inputs

Staged changes summary:

!`git diff --cached --stat`

Unstaged changes summary:

!`git diff --stat`

Branch changes (commits since main):

!`git log --oneline main..HEAD 2>/dev/null`

User argument: $ARGUMENTS

Determine What to Review

Parse $ARGUMENTS first:

• If argument is --unstaged → review unstaged changes only
• If argument is --branch → review all changes since main
• If argument is a file path → scope the review to that file only (use the appropriate diff source)
• If no argument (empty or blank) → use the 3-tier fallback below

3-tier fallback (no argument):

1. If the staged changes summary above has content → review staged changes
2. Else if the unstaged changes summary has content → review unstaged changes
3. Else if the branch log has content → review branch changes since main
4. Else → print "Nothing to review. Stage some changes with git add and try again." and stop

Fetch the Diff

Based on the determination above, run the appropriate command:

• Staged: git diff --cached (add -- <file> if scoped)
• Unstaged: git diff (add -- <file> if scoped)
• Branch: git diff main...HEAD (add -- <file> if scoped)

Large diffs (2000+ lines): If the diff stat shows 2000+ total lines changed, do NOT try to process the entire diff blob. Instead, review file-by-file — use git diff --cached -- <path> (or the equivalent) for each changed file, and use the Read tool to examine full file context when needed.

Review Checklist

Evaluate the diff against each category below. Skip categories with no findings entirely — do not print empty sections. Use the Read tool to check surrounding context in source files when the diff alone is ambiguous.

1. SECURITY

• Hardcoded secrets, API keys, tokens, or credentials in source code
• Sensitive data in EXPO_PUBLIC_ env vars (these are inlined into the client bundle and visible to users)
• Insecure storage: using AsyncStorage or localStorage for tokens/passwords (must use expo-secure-store)
• Unvalidated user input, XSS vectors, injection risks
• Exposed debug endpoints, console.log of sensitive data left in production code
• Permissions requested but not justified or not guarded
• Private API usage without dev-client-only guards

2. CODE QUALITY

• TypeScript strictness: missing types, any usage, unsafe casts, missing generics
• Error handling: unhandled promise rejections, missing try/catch on async calls, fetch without response.ok check
• Memory leaks: missing cleanup in useEffect, unsubscribed event listeners, uncancelled AbortControllers
• Stale closures in callbacks or effects with missing/incorrect dependency arrays
• Dead code, unused imports, unreachable branches
• Missing null/undefined checks on optional chains that could crash at runtime

3. PERFORMANCE & BATTERY

This app runs continuously while riding. Every wasted cycle drains battery and risks UI jank.

Rendering:

• Inline object/array literals in JSX props (style={{ ... }} created every render) — hoist to constants or useMemo
• Inline arrow functions as props (onPress={() => ...}) causing child re-renders — use useCallback
• Missing React.memo on expensive pure components that receive stable props
• Components that re-render on every parent render without needing to (check prop stability)
• useWindowDimensions preferred over Dimensions.get() (reactive vs stale)
• Large component trees without virtualization (FlatList/FlashList for lists)

Animations:

• Using RN's built-in Animated API instead of Reanimated (blocks JS thread)
• Reanimated: animating layout properties (width, height) instead of transforms (translateX, scale)
• Missing 'worklet' directive on functions passed to Reanimated's useAnimatedStyle, gesture handlers, or runOnUI
• Animated.loop without cleanup on unmount (keeps running after component unmounts)
• Animation duration >300ms (sluggish feel); prefer springs for natural motion
• setTimeout/setInterval for animation timing instead of Animated.delay() or Reanimated's withDelay
• PlatformColor values passed to Reanimated views (not supported — use static color values)

Location & Sensors:

• GPS watchPositionAsync without appropriate accuracy level (high accuracy drains battery fast)
• Missing distanceInterval or timeInterval on location watchers (fires too often)
• Location subscriptions not cleaned up on unmount
• Heading watchers running when not needed (e.g., when map is not visible)

Networking:

• API polling without debounce or interval guards (e.g., weather fetched every render)
• Missing AbortController for fetch requests that should cancel on unmount
• No staleTime / caching strategy for repeated API calls (re-fetches identical data)
• Large payloads fetched without pagination or field selection
• Coordinates not rounded/debounced before API calls (tiny GPS drift triggers unnecessary requests)

Timers & Background:

• setInterval without cleanup in useEffect return
• setTimeout chains instead of proper state machines or Reanimated sequences
• Background tasks that keep running when the app is in the background (use AppState listener)

Images & Assets:

• Large images without resizing or caching (expo-image preferred over RN Image)
• SVG components re-created every render instead of memoized
• Missing contentFit on images (defaults may cause layout thrashing)

4. PROJECT CONVENTIONS

These are enforced patterns for this project (from CLAUDE.md and codebase standards):

Documentation:

• All functions must have JSDoc with @param, @returns, @throws
• Exported functions additionally require @example

React 19 (SDK 54):

• React.use(Context) not useContext(Context)
• <Context value={}> not <Context.Provider value={}>
• ref as a regular prop, not forwardRef wrapper

Styling:

• Inline style objects, NOT StyleSheet.create
• borderCurve: 'continuous' on rounded corners (not capsule shapes)
• fontVariant: ['tabular-nums'] for numeric displays (speed, distance, timers)
• boxShadow CSS style, NOT legacy RN shadow/elevation styles
• Flex gap preferred over margin for spacing
• padding preferred over margin where possible

Platform & Imports:

• process.env.EXPO_OS not Platform.OS
• @/ path alias for all imports, not relative paths like ../
• useColorScheme from react-native, NOT from react

Haptics:

• Guard with if (process.env.EXPO_OS === 'ios') before expo-haptics calls

Library preferences (from expo-app-design skills):

• expo-image not RN Image
• expo-audio not expo-av
• expo-video not expo-av
• expo-secure-store for sensitive data, localStorage polyfill (expo-sqlite/localStorage) for preferences — never AsyncStorage
• react-native-safe-area-context not RN's SafeAreaView
• expo/fetch preferred over axios
• react-native-reanimated not RN Animated

5. EXPO / REACT NATIVE

• expo-router API misuse: wrong navigation method, missing _layout.tsx, co-located non-route files in app/
• Safe area: missing inset handling — use contentInsetAdjustmentBehavior="automatic" on ScrollView/FlatList, or react-native-safe-area-context
• Reanimated worklet correctness: missing 'worklet' directive, accessing JS-thread-only APIs from UI thread, reading .value outside useAnimatedStyle
• Native module bridge: synchronous calls across the bridge, missing error handling on native module calls
• Gesture handler: onPress on View instead of Pressable/TouchableOpacity, missing GestureDetector wrapper for Reanimated gestures
• expo-location / expo-sensors: permissions requested without checking granted status first
• Intrinsic HTML elements (div, img, span) used outside DOM components
• Dimensions.get() instead of useWindowDimensions (stale on rotation/resize)

6. MEMORY & RESOURCE MANAGEMENT

• Event listeners added without corresponding removal in cleanup
• expo-location / expo-sensors subscriptions not removed on unmount
• Large data structures (map tiles, weather history, GPS track arrays) growing unbounded without pruning
• Image/media resources not released after use
• SQLite connections or file handles opened without close
• Native module event emitters: addListener without storing and calling the returned remove() / Subscription.remove()
• setInterval / setTimeout IDs not cleared in useEffect cleanup
• Refs holding stale references to unmounted components
• Heavy objects stored in state when a ref would suffice (triggers unnecessary re-renders)

7. SUGGESTIONS

• Non-blocking improvements, refactoring ideas, readability enhancements
• Performance optimizations that aren't critical but would be nice to have
• These are informational only and should not affect the verdict

Output Format

Use this exact structure:

# Code Review: [staged|unstaged|branch] changes

> Reviewing N files, M insertions(+), K deletions(-)

## SECURITY
- `[error]` **file.ts:42** — Description of the finding
- `[warning]` **file.ts:88** — Description of the finding

## CODE QUALITY
- `[warning]` **file.ts:15** — Description of the finding

## PERFORMANCE & BATTERY
- `[warning]` **file.ts:30** — Description of the finding

## PROJECT CONVENTIONS
- `[info]` **file.ts:3** — Description of the finding

## EXPO / REACT NATIVE
- `[warning]` **file.ts:27** — Description of the finding

## MEMORY & RESOURCE MANAGEMENT
- `[warning]` **file.ts:60** — Description of the finding

## SUGGESTIONS
- `[info]` **file.ts:50** — Description of the suggestion

---

| Category | Errors | Warnings | Info |
|----------|--------|----------|------|
| Security | 0 | 1 | 0 |
| Code Quality | 0 | 1 | 0 |
| Performance & Battery | 0 | 1 | 0 |
| Conventions | 0 | 0 | 1 |
| Expo / RN | 0 | 1 | 0 |
| Memory & Resources | 0 | 1 | 0 |
| **Total** | **0** | **5** | **1** |

## Verdict: APPROVE / NEEDS CHANGES / BLOCK

[One-line summary of the overall assessment]

Verdict criteria:

• APPROVE — No errors, warnings are minor/acceptable
• NEEDS CHANGES — Has warnings that should be addressed before committing
• BLOCK — Has errors (security issues, critical bugs, performance problems that would drain battery or crash the app)

Important: Use real file paths and line numbers from the diff. Every finding must reference a specific location. Do not fabricate findings — if the code is clean, say so and APPROVE.

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