expo

Coding rules for Expo and React Native mobile apps. They cover navigation, shared components, platform-specific files, styling, screen safety, lists, and data fetching.

In plain words
What is it for?
Use them when building or reviewing Expo screens, routes, navigation, reusable components, platform-specific behavior, styles, and lists.
Why use it?
They help keep mobile code organized and avoid common problems across iPhone, Android, and web versions.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/nedcodes-ok/cursorrules-collection/expo
Clone the repo
git clone --depth 1 https://github.com/nedcodes-ok/cursorrules-collection
Per session 494 This file is loaded in full into every session.
When invoked 494 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00494 $0.00494
Opus 5 $0.00247 $0.00247
Sonnet 5 $0.00099 $0.00099
Haiku 4.5 $0.00049 $0.00049

Measured 3d ago against content hash b81a48128eb9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

expo scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

rules-mdc/frameworks/expo.mdc · 48 lines

How it starts

The opening of the file, as written. The whole thing — 48 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Expo Cursor Rules

You are an expert Expo/React Native developer. Follow these rules:

Project Structure

  • Use Expo Router for file-based navigation. Routes in app/ directory
  • Shared components in components/, hooks in hooks/, utils in utils/
  • Platform-specific files: Component.ios.tsx, Component.android.tsx, Component.web.tsx
  • Use expo-constants for app config. Access via Constants.expoConfig
  • File-based routing: app/(tabs)/index.tsx, app/[id].tsx, app/_layout.tsx
  • Use Stack, Tabs, Drawer from expo-router for layout types
  • Type-safe navigation with useRouter() and Link component
  • Deep linking configured via app.json scheme field
  • Use useLocalSearchParams() for route params, typed with generics

Components & Styling

  • StyleSheet.create() for all styles — never inline style objects
  • Use Pressable over TouchableOpacity. Better accessibility and customization
  • Platform.select() for platform-specific values, not runtime if/else
  • SafeAreaView (from react-native-safe-area-context) on all screen components
  • FlatList for lists, never ScrollView with .map() — virtualization matters

State & Data

  • TanStack Query for server state. AsyncStorage for local persistence
  • Zustand or Jotai for global client state — avoid Redux in Expo projects
  • Use expo-secure-store for sensitive data (tokens, credentials), not AsyncStorage
  • Handle offline state: check NetInfo, queue mutations, sync on reconnect

Native Features

  • Use Expo SDK modules first (expo-camera, expo-location, expo-notifications)
  • Request permissions with expo-* permission hooks. Handle denied state in UI
  • Use expo-image over React Native Image — better caching and performance
  • Animations: react-native-reanimated for complex, Animated API for simple

Build & Config

  • EAS Build for production builds. Never eject unless absolutely required
  • app.json/app.config.ts for all Expo config. Use config plugins for native customization
  • Environment variables via .env with expo-constants, not process.env
  • OTA updates with expo-updates. Set fallbackToCacheTimeout for reliability

Read the full file on GitHub · 48 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 48 lines · 494 tokens per session scan A b81a48128eb9

Subscribe to this mod's changes

expo is a cursor rule published in the GitHub repository nedcodes-ok/cursorrules-collection (37 stars, last pushed 6mo ago), licensed MIT. It adds 494 tokens to every session, about $0.0025 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.