Expo & React Native Cursor Rules (.mdc) | Modern Mobile Architecture

Production-grade architectural rulebook for React Native & Expo Router. Engineered to eliminate LLM hallucinations, enforce strict deterministic conventions, and prevent architectural drift across Cursor IDE, Claude Code CLI, and autonomous multi-agent pipelines.

Target Path
.cursor/rules/expo.mdc
Execution Scope
Glob Pattern Auto-Match
Specification Format
Frontmatter MDC (.mdc)
AI Tool Support
Cursor IDE & Composer
02 / DRIFT ANALYSIS & VALUE PROPOSITION

Failure Patterns Prevented for React Native & Expo Router

Without This Rule (Default LLM Behavior)Vulnerable

Modern React Native uses Expo Router v3/v4 with file-based layout groups (app/(tabs)), typed routes, and React Native New Architecture (Fabric/TurboModules). LLMs constantly generate obsolete React Navigation Stack wrappers, deprecated AsyncStorage imports, and un-safe-area layout overflows.

Hallucination Symptoms
  • Invokes deprecated or removed APIs from older model training weights
  • Generates conflicting configuration files and invalid imports
  • Silently drops type-safety, boundaries, or transaction isolation
With This Rule (Guaranteed Invariants)Deterministic
Use Expo Router file-based filesystem routing (app/_layout.tsx, app/(tabs)/index.tsx); ban legacy React Navigation container boilerplate.
Enforce react-native-safe-area-context (useSafeAreaInsets or SafeAreaView) for all top-level mobile screen boundaries.
Use modern Expo SDK native modules (expo-image, expo-secure-store, expo-crypto) instead of unmaintained bare native packages.
Optimize for React Native New Architecture (Fabric renderer): avoid synchronous layout measurements in render passes.
Always test cross-platform styling on both iOS and Android (e.g. elevation vs shadowColor, notch handling).
03 / VERIFIED CODE PATTERNS

Code Standards: Anti-Pattern vs Verified Implementation

Discouraged Anti-Pattern
// Discouraged: Missing safe-area insets, slow standard Image component, obsolete navigation prop
export default function BadProfile({ navigation }: any) {
  return (
    <div style={{ marginTop: 50 }}>
      <img src="avatar.png" />
      <button onClick={() => navigation.navigate("Home")}>Go</button>
    </div>
  );
}
Verified Production Standard
import { View, Text, StyleSheet } from "react-native";
import { Image } from "expo-image";
import { useSafeAreaInsets } from "react-native-safe-area-context";

export default function ProfileScreen() {
  const insets = useSafeAreaInsets();
  return (
    <View style={[styles.container, { paddingTop: insets.top, paddingBottom: insets.bottom }]}>
      <Image
        source={{ uri: "https://example.com/avatar.png" }}
        style={styles.avatar}
        contentFit="cover"
        transition={200}
      />
      <Text style={styles.title}>User Profile</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  container: { flex: 1, backgroundColor: "#fff", paddingHorizontal: 16 },
  avatar: { width: 80, height: 80, borderRadius: 40 },
  title: { fontSize: 20, fontWeight: "600", marginTop: 12 },
});
04 / REPOSITORY PLACEMENT & 3-STEP TERMINAL INSTALLATION

How to Install React Native & Expo Router Cursor Rules (.mdc) via Terminal

1

Step 1: Open Project Directory & Verify Target Placement

Open your terminal and navigate to your project root folder where the .cursor/rules/expo.mdc file will reside. Ensure the file is placed at the exact path below relative to your project root so the AI engine automatically loads it:

.cursor/rules/expo.mdc
2

Step 2: Fetch Rule File via Terminal Command

Run curl, PowerShell, or wget to stream the rule directly from the DevScratchpad raw API endpoint and write it to .cursor/rules/expo.mdc:

Terminal One-Liner Install

Run directly in your project root to stream and write this rule file with one command.

Raw API Stream
$mkdir -p ".cursor/rules" && curl -fsSL "https://www.devscratchpad.tech/api/raw/cursor-rules/react-native-expo" -o ".cursor/rules/expo.mdc"
3

Step 3: Verify and Activate with AI Agent

Launch your AI coding assistant (Cursor IDE & Composer). The assistant will automatically discover .cursor/rules/expo.mdc in your repository and apply the architectural guardrails, type constraints, and verification protocols during code generation.

05 / ROUTE DIRECTORY & CROSS-TOOLING
Format Pillar HubComprehensive Manual

Cursor Rules (.mdc) Directory & Generator

Inspect the complete specification manual, glob patterns, directory rules, and all available presets in our central directory.

/cursor-rules Directory
06 / FREQUENTLY ASKED QUESTIONS

Technical FAQ: React Native & Expo Router AI Rulebooks

Does this support Expo Router v3 and v4?

Yes, it enforces typed routes, layout groups (tabs), and useLocalSearchParams.

Why use expo-image over React Native Image?

expo-image provides hardware decoding, progressive loading, blurhash previews, and superior memory caching on iOS and Android.