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Mobile Offline Support

Offline-first mobile apps with local storage, sync queues, conflict resolution. Use for offline functionality, data sync, connectivity handling, or encountering sync conflicts, queue management, storage limits, network transition errors.

rag
By secondsky
17928Updated 1 day agoTypeScriptMIT

Skill Content

# Mobile Offline Support

Build offline-first mobile applications with local storage and synchronization.

## React Native Implementation

```javascript
import AsyncStorage from '@react-native-async-storage/async-storage';
import NetInfo from '@react-native-community/netinfo';

class OfflineManager {
  constructor() {
    this.syncQueue = [];
    this.isOnline = true;
    // Maximum items in sync queue before discarding oldest
    this.MAX_SYNC_QUEUE_LENGTH = 1000;

    NetInfo.addEventListener(state => {
      this.isOnline = state.isConnected;
      if (this.isOnline) this.processQueue();
    });
  }

  /**
   * Fetch data from server.
   * TODO: Replace with actual API endpoint implementation.
   */
  async fetchFromServer(key) {
    try {
      // Example implementation - replace with your API
      const response = await fetch(`${API_BASE_URL}/data/${key}`);
      if (!response.ok) {
        throw new Error(`Server returned ${response.status}`);
      }
      return await response.json();
    } catch (error) {
      console.error('fetchFromServer failed:', error);
      throw new Error(`Failed to fetch ${key}: ${error.message}`);
    }
  }

  /**
   * Sync data to server.
   * TODO: Replace with actual API endpoint implementation.
   */
  async syncToServer(key, data) {
    try {
      // Example implementation - replace with your API
      const response = await fetch(`${API_BASE_URL}/data/${key}`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(data)
      });
      if (!response.ok) {
        throw new Error(`Server returned ${response.status}`);
      }
      return await response.json();
    } catch (error) {
      console.error('syncToServer failed:', error);
      throw new Error(`Failed to sync ${key}: ${error.message}`);
    }
  }

  async getData(key) {
    const cached = await AsyncStorage.getItem(key);
    if (cached) return JSON.parse(cached);

    if (this.isOnline) {
      const data = await this.fetchFromServer(key);
      await AsyncStorage.setItem(key, JSON.stringify(data));
      return data;
    }

    return null;
  }

  async saveData(key, data) {
    await AsyncStorage.setItem(key, JSON.stringify(data));

    if (this.isOnline) {
      await this.syncToServer(key, data);
    } else {
      // Add to queue
      this.syncQueue.push({ key, data, timestamp: Date.now() });

      // Enforce queue bounds - discard oldest if exceeded
      while (this.syncQueue.length > this.MAX_SYNC_QUEUE_LENGTH) {
        const discarded = this.syncQueue.shift();
        console.warn(`Sync queue full - discarded oldest item: ${discarded.key}`);
      }

      // Persist trimmed queue
      await AsyncStorage.setItem('syncQueue', JSON.stringify(this.syncQueue));
    }
  }

  async processQueue() {
    const failedItems = [];
    for (const item of this.syncQueue) {
      try {
        await this.syncToServer(item.key, item.data);
      } catch (err) {
        console.error('Sync failed:', err);
        failedItems.push(item);
      }
    }
    this.syncQueue = failedItems;
    if (failedItems.length === 0) {
      await AsyncStorage.removeItem('syncQueue');
    } else {
      await AsyncStorage.setItem('syncQueue', JSON.stringify(failedItems));
    }
  }
}
```

## Conflict Resolution

```javascript
function resolveConflict(local, server) {
  // Last-write-wins
  if (local.updatedAt > server.updatedAt) return local;
  return server;

  // Or merge changes
  // return { ...server, ...local };
}
```

## UI Indicators

```jsx
function OfflineIndicator() {
  const [isOnline, setIsOnline] = useState(true);

  useEffect(() => {
    return NetInfo.addEventListener(state => {
      setIsOnline(state.isConnected);
    });
  }, []);

  if (isOnline) return null;

  return (
    <View style={styles.banner}>
      <Text>You're offline. Changes will sync when connected.</Text>
    </View>
  );
}
```

## Best Practices

- Cache frequently accessed data locally
- Queue actions for later sync
- Show clear offline indicators
- Handle sync conflicts gracefully
- Compress stored data
- Test offline scenarios thoroughly

## Native Implementations

See [references/native-implementations.md](references/native-implementations.md) for:
- iOS Core Data with sync manager
- Android Room database with WorkManager sync

## Avoid

- Assuming connectivity
- Losing data on sync failures
- Unbounded queue growth
- Syncing sensitive data insecurely

How to use

  1. Copy the skill content above
  2. Create a .claude/skills directory in your project
  3. Save as .claude/skills/claude-skills-mobile-offline-support.md
  4. Use /claude-skills-mobile-offline-support in Claude Code to invoke this skill

README

View on GitHub

Claude Code Skills Collection

170 production-ready skills for Claude Code CLI

Version 3.3.1 | Last Updated: 2026-05-14

<div align="center">

šŸ”Œ Platform Support

This repository uses Claude Plugin Patterns ā€” natively supported by:

PlatformStatusNotes
Claude Codeāœ… NativeFull marketplace support
Factory Droidāœ… NativeFull marketplace support
</div> **For all other Platforms like opencode, codex and others, you can use https://github.com/enulus/OpenPackage **

A curated collection of battle-tested skills for building modern web applications with Cloudflare, AI integrations, React, Tailwind, and more.

PS: if skills.sh warns about any skill: Their scan process is a outdated LLM which flags newest versions pins (like in ZOD) as non existent and by that potentially malicous.

Quick Start

Marketplace Installation (Recommended)

# Add the marketplace
/plugin marketplace add https://github.com/secondsky/claude-skills

# Install individual skills as needed
/plugin install cloudflare-d1@claude-skills
/plugin install tailwind-v4-shadcn@claude-skills
/plugin install ai-sdk-core@claude-skills

See MARKETPLACE.md for complete catalog of all 170 skills.

Bulk Installation (Contributors)

# Clone the repository
git clone https://github.com/secondsky/claude-skills.git
cd claude-skills

# Install all 170 skills at once
./scripts/install-all.sh

# Or install individual skills
./scripts/install-skill.sh cloudflare-d1

Repository Structure

This repository contains 170 production-tested skills for Claude Code, each focused on a specific technology or capability.

Individual Skills: Each skill is a standalone unit with:

  • SKILL.md - Core knowledge and guidance
  • Templates - Working code examples
  • References - Extended documentation
  • Scripts - Helper utilities

Installation Options:

  1. Individual - Install only the skills you need via marketplace
  2. Bulk - Install all 170 skills using ./scripts/install-all.sh

Available Skills (170 Individual Skills)

Each skill is individually installable. Install only the skills you need.

Full Catalog: See MARKETPLACE.md for detailed listings.

Categories

CategorySkillsExamples
tooling29turborepo, plan-interview, code-review
frontend26nuxt-v4, nuxt-v5, tailwind-v4-shadcn, tanstack-query, nuxt-studio, maz-ui, threejs
cloudflare21cloudflare-d1, cloudflare-workers-ai, cloudflare-agents
ai20openai-agents, claude-api, ai-sdk-core
api16api-design-principles, graphql-implementation
web10hono-routing, firecrawl-scraper, web-performance
mobile7swift-best-practices, react-native-app, react-native-skills
database6drizzle-orm-d1, neon-vercel-postgres, supabase-postgres-best-practices
security6csrf-protection, access-control-rbac
auth4better-auth
testing4vitest-testing, playwright-testing
design4design-review, design-system-creation
woocommerce4woocommerce-backend-dev
cms4hugo, sveltia-cms, wordpress-plugin-core
architecture3microservices-patterns, architecture-patterns
data3sql-query-optimization, recommendation-engine
seo2seo-optimizer, seo-keyword-cluster-builder
documentation1technical-specification

How It Works

Auto-Discovery

Claude Code automatically checks ~/.claude/skills/ for relevant skills before planning tasks:

User: "Set up a Cloudflare Worker with D1 database"
           ā†“
Claude: [Checks skills automatically]
           ā†“
Claude: "Found cloudflare-d1 skills.
         These prevent 12 documented errors. Use them?"
           ā†“
User: "Yes"
           ā†“
Result: Production-ready setup, zero errors, ~65% token savings

Note: Due to token limits, not all skills may be visible at once. See āš ļø Important: Token Limits below.

Skill Structure

Each skill includes:

skills/[skill-name]/
ā”œā”€ā”€ SKILL.md              # Complete documentation
ā”œā”€ā”€ .claude-plugin/
ā”‚   ā””ā”€ā”€ plugin.json       # Plugin metadata
ā”œā”€ā”€ templates/            # Ready-to-copy templates
ā”œā”€ā”€ scripts/              # Automation scripts
ā””ā”€ā”€ references/           # Extended documentation

Recent Additions

May 2026

Supply Chain Security (cross-cutting):

  • dependency-upgrade expanded with Socket CLI integration ā€” proactive malicious package detection, typosquatting alerts, and CI/CD security gates. New 418-line reference guide, 2 GitHub Actions templates, and expanded supply chain security comparison (3 tools)
  • 31 skills now include "Secure Installation" guidance ā€” contextually-tailored security sections across all high-risk skill categories (scaffolding, MCP/agent SDKs, multi-provider installs, Docker, CI/CD). Covers 8 Bun skills, 5 Nuxt skills, 6 Cloudflare skills, 4 AI/agent skills, and 8 frontend/tooling skills
  • Supply chain security is now a first-class cross-cutting concern woven into the skill collection ā€” not a standalone topic

February - April 2026

Full-Stack Frameworks:

  • nuxt-v5 (v1.0.0) - Full Nuxt 5 support with 4 skills (core, data, server, production), 3 diagnostic agents, and interactive setup wizard
  • supabase-postgres-best-practices - 30 Postgres optimization rules from Supabase across 8 categories
  • threejs (v1.0.0) - 3D web graphics: scenes, geometries, shaders, animations, post-processing

Infrastructure:

  • JSON schema validation - Automated plugin.json validation with CI support
  • GitHub issue templates - Skill-specific issue templates for bug reports, feature requests, and submissions

Plugin Enhancements:

  • mutation-testing - Added Bun native runner support
  • dependency-upgrade - Added supply chain security content

December 2025 - January 2026

Frontend Expansion:

  • nuxt-studio (v1.0.0) - Visual CMS for Nuxt Content with live preview, OAuth auth, and R2 storage integration
  • maz-ui (v1.0.0) - 50+ Vue/Nuxt components with theming, i18n, form generation, and 14 composables

Developer Workflow:

  • plan-interview (v2.0.0) - Adaptive interview-driven spec generation with autonomous quality review
  • turborepo (v2.8.0) - Updated to official Vercel skill with enhanced monorepo build optimization

Mobile Development:

  • react-native-skills (v1.0.0) - React Native & Expo best practices with performance optimization patterns

Enhanced Authentication:

  • better-auth (v2.2.0) - Expanded to 18 framework integrations with 30+ authentication plugins

āš ļø Important: Token Limits

Skill Visibility Constraint

Claude Code has a 15,000 character limit for the total size of skill descriptions in the system prompt. This limit also applies to commands and agents.

What this means:

  • Not all 170 skills may be visible in Claude's context at once
  • Skills are loaded based on relevance and available token budget
  • You can verify how many skills Claude currently sees by asking: "How many skills do you see in your system prompt?"

Checking Visible Skills

To verify which skills are currently loaded:

# Ask Claude Code directly
"Check what skills/plugins you see in your system prompt"

Claude will report something like: "85 of 170 skills visible due to token limits"

Workaround: Increase Token Budget

You can double the headroom for skill descriptions by setting an environment variable:

# Increase limit to 30,000 characters
export SLASH_COMMAND_TOOL_CHAR_BUDGET=30000

# Then launch Claude Code
claude

This gives you approximately 2x more skill visibility in the system prompt.

Note: This is a temporary workaround. The Claude Code team is working on better solutions for skill discovery and loading.

Token Efficiency

MetricManual SetupWith SkillsSavings
Average Tokens12,000-15,0004,000-5,000~65%
Typical Errors2-4 per service0 (prevented)100%
Setup Time2-4 hours15-45 minutes~80%

Across all 170 skills: 400+ documented errors prevented.

Contributing

Prerequisites for Contributors

Install the official plugin development toolkit:

/plugin install plugin-dev@claude-code-marketplace

This provides:

  • /plugin-dev:create-plugin command (8-phase guided workflow)
  • 7 comprehensive skills (hooks, MCP, structure, agents, commands, skills)
  • 2 specialized agents (agent-creator, plugin-validator)

Quick Steps

  1. Create skill directory in plugins/
  2. Add SKILL.md with YAML frontmatter
  3. Run ./scripts/sync-plugins.sh
  4. Submit pull request

See CONTRIBUTING.md and PLUGIN_DEV_BEST_PRACTICES.md for detailed guidelines.

Documentation

DocumentPurpose
START_HERE.mdStart here! Quick navigation guide
PLUGIN_DEV_BEST_PRACTICES.mdRepository-specific best practices (marketplace, budget, quality)
MARKETPLACE.mdFull skill catalog and installation guide
MARKETPLACE_MANAGEMENT.mdTechnical infrastructure (plugin.json, scripts, validation)
CLAUDE.mdProject context and development standards
CONTRIBUTING.mdContribution guidelines

Links

Built with ā¤ļø by Claude Skills Maintainers

View source on GitHub

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