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mobile-pro skill

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This skill helps you master cross-platform mobile performance by leveraging Expo SDK 54, React Native Fabric, and Compose Multiplatform for native-like 120fps

npx playbooks add skill yuniorglez/gemini-elite-core --skill mobile-pro

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SKILL.md
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---
name: mobile-pro
id: mobile-pro
version: 1.1.0
description: "Senior Mobile Engineer. Expert in Expo SDK 54+, React Native New Architecture (Fabric), and Compose Multiplatform."
---

# 📱 Skill: Mobile Pro (v1.1.0)

## Executive Summary
The `mobile-pro` is an elite specialist in cross-platform mobile development. In 2026, building mobile apps is about **Native-Grade Performance**, **On-Device Intelligence**, and **Architectural Unity**. This skill focuses on mastering **Expo SDK 54**, the **React Native New Architecture (Fabric)**, and **Compose Multiplatform** to deliver premium, 120fps experiences on any device. We bridge the gap between shared logic and native feel.

---

## 📋 Table of Contents
1. [Core Mobile Philosophies](#core-mobile-philosophies)
2. [The "Do Not" List (Anti-Patterns)](#the-do-not-list-anti-patterns)
3. [Expo SDK 54 Mastery](#expo-sdk-54-mastery)
4. [Reanimated 4 & Worklets](#reanimated-4--worklets)
5. [React Native New Architecture](#react-native-new-architecture)
6. [Compose Multiplatform Standards](#compose-multiplatform-standards)
7. [Reference Library](#reference-library)

---

## 🏗️ Core Mobile Philosophies

1.  **Performance is the UX**: If it's not 120fps, it's a bug. Use worklets for all gesture logic.
2.  **Shared Logic, Native Feel**: Use cross-platform frameworks for 90% of the code, but never compromise on platform-specific UI nuances (e.g., iOS Liquid Glass).
3.  **On-Device Intelligence**: Leverage local vector DBs (SQLite VEC) for privacy-first AI features.
4.  **Zero Bridge Policy**: Fully embrace JSI and Fabric. No more slow JSON serialization.
5.  **Security-First Storage**: Never use `AsyncStorage` for sensitive data; use `expo-secure-store`.

---

## 🚫 The "Do Not" List (Anti-Patterns)

| Anti-Pattern | Why it fails in 2026 | Modern Alternative |
| :--- | :--- | :--- |
| **Bridge-Based Modules**| High latency and overhead. | Use **JSI & TurboModules**. |
| **`SafeAreaView` (RN)** | Deprecated in SDK 54. | Use **`react-native-safe-area-context`**. |
| **Manual Build Scripts** | Slow and hard to maintain. | Use **Expo EAS & Prebuild**. |
| **Inline Styles** | Degrades performance. | Use **StyleSheet.create**. |
| **JSON Web Tokens (local)**| Vulnerable to extraction. | Use **Secure Enclaves / Keychains**. |

---

## 🚀 Expo SDK 54 Mastery

The standard for 2026:
-   **Native iOS Builds**: 10x faster local development.
-   **iOS 26 Liquid Glass**: Seamless integration with Apple's latest design language.
-   **Edge-to-Edge Android**: Default target for API 36+.

*See [References: Expo SDK 54](./references/expo-sdk-54-features.md) for details.*

---

## ⚡ Reanimated 4 & Worklets

Run complex logic directly on the UI thread.
-   **Worklet Directives**: `'worklet';` for isolated execution.
-   **CSS Animations**: Native support for standard CSS syntax.
-   **Gesture Orchestration**: Zero-latency tactile response.

---

## 📖 Reference Library

Detailed deep-dives into Mobile Excellence:

- [**Expo SDK 54 Features**](./references/expo-sdk-54-features.md): The 2026 standard.
- [**Reanimated 4 Worklets**](./references/reanimated-4-worklets.md): Concurrent JS on the UI thread.
- [**New Architecture (Fabric)**](./references/new-architecture-fabric.md): Moving beyond the bridge.
- [**Compose Multiplatform**](./references/compose-multiplatform-2026.md): Native quality everywhere.

---

*Updated: January 22, 2026 - 20:20*

Overview

This skill is a senior mobile engineering specialist focused on delivering native-grade, cross-platform apps using Expo SDK 54, the React Native New Architecture (Fabric), and Compose Multiplatform. It codifies performance-first philosophies, modern tooling, and secure on-device intelligence patterns to reach 120fps experiences and consistent platform UX. The guidance is pragmatic and battle-tested for 2026 mobile requirements.

How this skill works

The skill inspects architecture choices, runtime paths, and build flows to eliminate bridge-based bottlenecks and enable JSI/TurboModules and Fabric. It recommends concrete libraries, runtime directives (e.g., worklets for Reanimated 4), and Expo/EAS workflows to speed iteration while keeping native integrations and secure storage. It also prescribes on-device AI patterns like local vector DBs and secure enclaves for privacy-sensitive features.

When to use it

  • Building cross-platform apps that must feel native on iOS and Android while sharing most logic.
  • Optimizing performance-critical UI and gesture interactions to reach 120fps and zero-latency feedback.
  • Migrating legacy bridge-based React Native modules to the new architecture (Fabric/JSI).
  • Implementing local AI features with privacy-first storage and vector search.
  • Setting up modern Expo-based CI/CD and prebuild flows for reproducible native releases.

Best practices

  • Treat performance as UX: push animation and gesture logic into worklets on the UI thread.
  • Adopt JSI/TurboModules and Fabric; avoid JSON bridge calls for performance-sensitive code.
  • Use Expo EAS and prebuilds to standardize builds and speed native development loops.
  • Store secrets in secure enclaves/keychains or expo-secure-store; never keep sensitive data in AsyncStorage.
  • Prefer StyleSheet.create and platform-specific UI refinements over inline styles.
  • Use local vector DBs (SQLite VEC) for on-device intelligence and privacy-first search.

Example use cases

  • Rewriting a high-interaction animation screen to use Reanimated 4 worklets and Fabric to eliminate jank.
  • Migrating a large app from bridge modules to JSI/TurboModules to reduce latency and memory overhead.
  • Building an offline-first assistant using local vector embeddings with secure storage for private user data.
  • Standardizing builds across teams with Expo SDK 54 and EAS to reduce 'it works on my machine' issues.
  • Delivering a Compose Multiplatform UI layer that shares business logic while preserving native look-and-feel.

FAQ

Do I need to drop existing bridge-based modules immediately?

Not immediately; prioritize modules on the hot path (animations, gestures, frequent I/O) and plan staged migration to JSI/TurboModules.

Is Expo SDK 54 required to follow these practices?

Expo SDK 54 is the recommended baseline for the 2026 workflow, but many principles (JSI, worklets, secure storage) apply across compatible RN and Compose setups.