# expo

Expo and React Native performance guide that directs coding agents to optimize app launch, bundle size, list virtualization, and memory usage.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 553 installs · ★ 218
- Author: pproenca
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/pproenca/dot-skills/tree/HEAD/skills/.curated/expo/SKILL.md
- Updated: 2026-08-15
- HTML: https://affpapa.org/en/nevibecode/skills/expo

## What it does

The skill equips the agent with 54 performance guidelines grouped into 9 impact tiers. Top priority goes to critical startup gains, like managing splash screens, preloading assets, enabling Hermes, and trimming bundle bloat by dropping barrel files and unused dependencies.

It enforces concrete component conventions. For lists, it mandates FlashList over FlatList with accurate item estimates. For assets, it defaults to `expo-image` alongside WebP or BlurHash placeholders. Animations run on the UI thread via Reanimated, while hooks receive clean teardowns to prevent closure leaks.

The entire rulebook focuses strictly on Expo and React Native projects. Using it outside this framework ecosystem produces irrelevant advice.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill expo -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/expo/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/expo/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill expo -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/expo/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill expo -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/expo/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install pproenca/dot-skills expo
```

2. **Manually: put the files in place**
- File: `.github/skills/expo/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill expo -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/pproenca/dot-skills --path skills/.curated/expo
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/expo/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill expo -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/pproenca/dot-skills/tree/HEAD/skills/.curated/expo/SKILL.md

## When to use it
- speed up app cold starts using Hermes and deferred loading
- shrink release bundle size and strip unneeded dependencies
- replace FlatList with FlashList to eliminate scroll stutter
- migrate image rendering to expo-image with placeholder support
- prevent closure leaks and abort pending fetch requests on unmount

## Example prompts
- Refactor this product feed to use FlashList and memoized item components.
- Review App.js to optimize startup time and minimize root imports.
- Switch our image components to expo-image with WebP format and blurhash placeholders.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 53be4a964d6e9950.

BEGIN THIRD-PARTY FILE 53be4a964d6e9950
```text
---
name: expo
description: Expo React Native performance optimization guidelines. This skill should be used when writing, reviewing, or refactoring Expo React Native code to ensure optimal performance patterns. Triggers on tasks involving React Native components, navigation, lists, images, animations, bundle optimization, or mobile performance improvements.
---

# Community Expo React Native Best Practices

Comprehensive performance optimization guide for Expo React Native applications. Contains 54 rules across 9 categories, prioritized by impact to guide automated refactoring and code generation.

## When to Apply

Reference these guidelines when:
- Writing new Expo React Native components
- Optimizing app startup and Time to Interactive
- Implementing lists, images, or animations
- Reducing bundle size and memory usage
- Reviewing code for mobile performance issues

## Rule Categories by Priority

| Priority | Category | Impact | Prefix |
|----------|----------|--------|--------|
| 1 | Launch Time Optimization | CRITICAL | `launch-` |
| 2 | Bundle Size Optimization | CRITICAL | `bundle-` |
| 3 | List Virtualization | HIGH | `list-` |
| 4 | Image Optimization | HIGH | `image-` |
| 5 | Data Fetching Patterns | HIGH | `data-` |
| 6 | Navigation Performance | MEDIUM-HIGH | `nav-` |
| 7 | Re-render Prevention | MEDIUM | `rerender-` |
| 8 | Animation Performance | MEDIUM | `anim-` |
| 9 | Memory Management | LOW-MEDIUM | `mem-` |

## Quick Reference

### 1. Launch Time Optimization (CRITICAL)

- `launch-splash-screen-control` - Control splash screen visibility during asset loading
- `launch-preload-critical-assets` - Preload fonts and images during splash
- `launch-hermes-engine` - Use Hermes engine for faster startup
- `launch-defer-non-critical` - Defer non-critical initialization
- `launch-new-architecture` - Enable New Architecture for synchronous native communication
- `launch-minimize-root-imports` - Minimize imports in root App component

### 2. Bundle Size Optimization (CRITICAL)

- `bundle-avoid-barrel-files` - Avoid barrel file imports
- `bundle-analyze-size` - Analyze bundle size before release
- `bundle-remove-unused-dependencies` - Remove unused dependencies
- `bundle-split-by-architecture` - Generate architecture-specific APKs
- `bundle-enable-proguard` - Enable ProGuard for Android release builds
- `bundle-optimize-fonts` - Subset custom fonts to used characters
- `bundle-use-lightweight-alternatives` - Use lightweight library alternatives

### 3. List Virtualization (HIGH)

- `list-use-flashlist` - Use FlashList instead of FlatList
- `list-provide-estimated-size` - Provide accurate estimatedItemSize
- `list-avoid-inline-functions` - Avoid inline functions in renderItem
- `list-provide-getitemlayout` - Provide getItemLayout for fixed-height items
- `list-avoid-key-prop` - Avoid key prop inside FlashList items
- `list-batch-rendering` - Configure list batch rendering
- `list-memoize-item-components` - Memoize list item components

### 4. Image Optimization (HIGH)

- `image-use-expo-image` - Use expo-image instead of React Native Image
```
END THIRD-PARTY FILE 53be4a964d6e9950

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