Expo Router Expert

Purpose

Provide expert guidance on Expo Router, the file-based routing and navigation library for React Native and Expo apps.

When to Use

Auto-invoke when users mention:

• Expo Router or file-based routing
• App directory structure
• Navigation in Expo apps
• Dynamic routes or route parameters
• Layouts and nested routes
• Deep linking
• Tab navigation or stack navigation

Knowledge Base

Expo Router documentation in

.Codex/skills/frontend/expo/docs/

Search patterns:

• Grep "expo router|router|routing" .Codex/skills/frontend/expo/docs/ -i

• Grep "navigation|layout|dynamic route" .Codex/skills/frontend/expo/docs/ -i

• Grep "app directory|deep link" .Codex/skills/frontend/expo/docs/ -i

Coverage Areas

File-Based Routing

• app/ directory structure
• Route conventions
• Index routes
• Dynamic routes ([id].tsx)
• Catch-all routes ([...slug].tsx)

Navigation

• useRouter hook
• useLocalSearchParams hook
• Link component
• Programmatic navigation
• Navigation state

Layouts

• Root layout (_layout.tsx)
• Nested layouts
• Layout groups (parentheses)
• Shared UI elements
• Layout persistence

Route Types

• Stack navigation
• Tab navigation
• Drawer navigation
• Modal routes
• Web-style navigation

Advanced Features

• Deep linking
• URL parameters
• Query strings
• Route guards
• TypeScript typed routes
• SEO (web)

API Routes

• Server endpoints
• API handlers
• Request/response

Response Format

## [Router Topic]

[Overview of routing feature]

### File Structure

app/ _layout.tsx # Root layout index.tsx # Home screen [id].tsx # Dynamic route (tabs)/ # Layout group _layout.tsx # Tab layout home.tsx profile.tsx

### Implementation

```typescript
// app/[id].tsx
import { useLocalSearchParams } from 'expo-router';

export default function DetailScreen() {
  const { id } = useLocalSearchParams();
  return <View>...</View>;
}

Navigation

import { useRouter, Link } from 'expo-router';

// Programmatic
const router = useRouter();
router.push('/details/123');

// Declarative
<Link href="/details/123">View Details</Link>

Key Concepts

• File system = route structure
• Automatic TypeScript types
• Universal navigation (iOS/Android/Web)

Source:

.Codex/skills/frontend/expo/docs/[filename].md

## Key Patterns

**Stack Navigation:**

app/ _layout.tsx # Stack index.tsx details.tsx

**Tab Navigation:**

app/ (tabs)/ _layout.tsx # Tab layout home.tsx profile.tsx

**Dynamic Routes:**

app/ posts/ [id].tsx # /posts/123 [...slug].tsx # /posts/a/b/c

## Always

- Reference Expo documentation
- Show file structure examples
- Provide TypeScript examples
- Explain navigation patterns
- Include deep linking setup
- Consider web compatibility