🍎📚 Cupertino

Apple Documentation Crawler & MCP Server

A Swift-based tool to crawl, index, and serve Apple's developer documentation to AI agents via the Model Context Protocol (MCP).

What is Cupertino?

Cupertino is a local, structured, AI-ready documentation system for Apple platforms. It:

• Crawls Apple Developer documentation, Swift.org, Swift Evolution proposals, Human Interface Guidelines, Apple Archive legacy guides, and Swift package metadata
• Indexes everything into a fast, searchable SQLite FTS5 database with BM25 ranking
• Serves documentation to AI agents like Claude via the Model Context Protocol
• Provides offline access to 302,424+ documentation pages across 307 frameworks

Why Build This?

• No more hallucinations: AI agents get accurate, up-to-date Apple API documentation
• Offline development: Work with full documentation without internet access
• Deterministic search: Same query always returns same results
• Local control: Own your documentation, inspect the database, script workflows
• AI-first design: Built specifically for AI agent integration via MCP

Quick Start

Note: When building from source, commands must be run from the Packages directory. The one-command install works from anywhere.

Requirements

• macOS 15+ (Sequoia)
• ~2-3 GB disk space for full documentation

Building from source additionally requires Swift 6.2+ and Xcode 16.0+

Installation

One-command install (recommended):

bash  **Note:** Use `/opt/homebrew/bin/cupertino` for Homebrew on Apple Silicon, `/usr/local/bin/cupertino` for Intel or manual install. Run `which cupertino` to find your path.

2. **Restart Claude Desktop**

3. **Ask Claude about Apple APIs:**
   - "Search for SwiftUI documentation"
   - "What does Swift Evolution proposal SE-0001 propose?"
   - "List available frameworks"

### Use with Claude Code

If you're using [Claude Code](https://code.claude.com/docs/en/overview), you can add Cupertino as an MCP server with a single command:

```bash
claude mcp add cupertino --scope user -- $(which cupertino)

This registers Cupertino globally for all your projects. Claude Code will automatically have access to Apple documentation search.

Use with OpenAI Codex

If you're using OpenAI Codex, add Cupertino with:

codex mcp add cupertino -- $(which cupertino) serve

Or add directly to ~/.codex/config.toml:

[mcp_servers.cupertino]
command = "/opt/homebrew/bin/cupertino"  # Homebrew on Apple Silicon
# command = "/usr/local/bin/cupertino"   # Intel Mac or manual install
args = ["serve"]

Tip: Run which cupertino to find your installation path.

Use with Cursor

Add to .cursor/mcp.json in your project (or ~/.cursor/mcp.json for global access):

{
  "mcpServers": {
    "cupertino": {
      "command": "/opt/homebrew/bin/cupertino",
      "args": ["serve"]
    }
  }
}

Use with VS Code (GitHub Copilot)

Add to .vscode/mcp.json in your workspace:

{
  "servers": {
    "cupertino": {
      "type": "stdio",
      "command": "/opt/homebrew/bin/cupertino",
      "args": ["serve"]
    }
  }
}

Use with Zed

Add to your Zed settings.json:

{
  "context_servers": {
    "cupertino": {
      "command": "/opt/homebrew/bin/cupertino",
      "args": ["serve"]
    }
  }
}

Use with Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "cupertino": {
      "command": "/opt/homebrew/bin/cupertino",
      "args": ["serve"]
    }
  }
}

Use with opencode

Add to opencode.jsonc:

{
  "mcp": {
    "cupertino": {
      "type": "local",
      "command": ["/opt/homebrew/bin/cupertino", "serve"]
    }
  }
}

Note: All examples use /opt/homebrew/bin/cupertino (Homebrew on Apple Silicon). Use /usr/local/bin/cupertino for Intel Macs or manual installs. Run which cupertino to find your path.

What You Get

Once configured, Claude Desktop can search your local documentation:

Search Results Example:

# Search Results for "SwiftUI"

Found **20** results:

## 1. NSHostingView | Apple Developer Documentation
- **Framework:** `swiftui`
- **URI:** `apple-docs://swiftui/documentation_swiftui_nshostingview`
- **Score:** 1.82

An AppKit view that hosts a SwiftUI view hierarchy.

## 2. UIHostingController | Apple Developer Documentation
- **Framework:** `swiftui`
- **URI:** `apple-docs://swiftui/documentation_swiftui_uihostingcontroller`

A UIKit view controller that manages a SwiftUI view hierarchy.
...

Framework Statistics:

Framework	Documents
Kernel	39,396
Matter	24,320
Swift	17,466
AppKit	12,443
Foundation	12,423
UIKit	11,158
Accelerate	9,114
SwiftUI	7,062
...	...
307 Frameworks	302,424

Core Features

1. Multi-Source Documentation Fetching

• Apple Developer Documentation (301,000+ pages)

  • JavaScript-aware rendering via WKWebView
  • HTML to Markdown conversion
  • Smart change detection

• Swift Evolution Proposals (~400 proposals)

  • GitHub-based fetching
  • Markdown format
  • Fast downloads

• Swift.org Documentation

  • Official Swift language docs
  • Clean HTML structure

• Swift Package Metadata

  • Priority package catalogs
  • README files

• Apple Sample Code (606 projects)

  • Two fetch methods: GitHub (recommended) or Apple website
  • Full-text search across all source files
  • 18,000+ indexed Swift files

• Apple Archive Legacy Guides (~75 pages)

  • Pre-2016 programming guides (Core Animation, Quartz 2D, Core Text, etc.)
  • Deep conceptual knowledge not in modern docs
  • Excluded from search by default (use --include-archive)

• Human Interface Guidelines

  • Apple's official design guidelines for all platforms
  • Covers iOS, macOS, watchOS, visionOS, and tvOS
  • Design patterns, components, foundations, and best practices

2. Bundled Resources

Cupertino includes pre-indexed catalog data bundled directly into the application:

• Swift Packages Catalog (9,699 packages)

  • Manually curated from Swift Package Index + GitHub API
  • Includes package metadata, stars, licenses, descriptions
  • Updated periodically by maintainers

• Sample Code Catalog (606 entries)

  • Apple's official sample code projects
  • Includes titles, descriptions, frameworks, download URLs
  • Bundled because Apple's catalog doesn't change frequently

• Priority Packages (36 curated packages)

  • Apple official packages (31) + essential ecosystem packages (5)
  • High-priority Swift packages for quick access

These catalogs are indexed during cupertino save and enable instant search without requiring multi-hour downloads. You can still fetch package READMEs and sample code separately via cupertino fetch if needed.

3. Full-Text Search Engine

• Technology: SQLite FTS5 with BM25 ranking
• Features:
  • Porter stemming (e.g., "running" matches "run")
  • Framework filtering
  • Platform availability filtering (iOS/macOS version)
  • Snippet generation
  • Sub-100ms query performance
• Size: ~2.4GB index for full documentation (302,000+ documents across 307 frameworks)
• Storage: Database must be on local filesystem - SQLite does not work reliably on network drives (NFS/SMB)

4. Model Context Protocol Server

• Resources: Direct access to documentation pages
  • apple-docs://{framework}/{page}
  • swift-evolution://{proposal-id}
  • hig://{category}/{page}
• Tools: Search and read capabilities for AI agents
  • Documentation Tools (requires cupertino save):
    • search_docs - Full-text search across all documentation
      • Parameters: query (required), source, framework, min_ios, min_macos, include_archive, limit (all optional)
    • search_hig - Search Human Interface Guidelines
      • Parameters: query (required), platform (optional), category (optional), limit (optional)
    • list_frameworks - List available frameworks
    • read_document - Read document by URI with format option
      • Parameters: uri (required), format (optional: json or markdown, default: json)
      • JSON format returns the full structured document data (recommended for AI)
      • Markdown format returns rendered content for human reading
  • Sample Code Tools (requires cupertino index):
    • search_samples - Search sample code projects and files
    • list_samples - List all indexed sample projects
    • read_sample - Read sample project README and metadata
    • read_sample_file - Read specific source file from a sample

5. Intelligent Crawling

• Resumable: Continue interrupted crawls from saved state
• Change Detection: Skip unchanged pages on updates
• Respectful: 0.5s default delay between requests (configurable)
• Deduplication: Automatic URL queue management
• Priority Queues: Important content fetched first

Commands

Command	Description
cupertino	Start MCP server (default)
cupertino setup	Download pre-built databases from GitHub
cupertino serve	Start MCP server
cupertino fetch	Download documentation
cupertino save	Build search index
cupertino search	Search documentation from CLI
cupertino read	Read full document by URI
cupertino doctor	Check server health
cupertino index	Index sample code for search
cupertino cleanup	Clean up sample code archives

See docs/commands/ for detailed usage and options.

Architecture

Cupertino uses an ExtremePackaging architecture with 9 consolidated packages:

Foundation Layer:
  ├─ MCP                    # Consolidated MCP framework (Protocol + Transport + Server)
  ├─ Logging                # os.log infrastructure
  └─ Shared                 # Configuration & models

Infrastructure Layer:
  ├─ Core                   # Crawler & downloaders
  └─ Search                 # SQLite FTS5 search

Application Layer:
  ├─ MCPSupport             # Resource providers
  ├─ SearchToolProvider     # Search tool implementations
  └─ Resources              # Embedded resources

Executables:
  ├─ CLI                    # Unified cupertino binary
  ├─ TUI                    # Terminal UI (cupertino-tui)
  └─ MockAIAgent            # Testing tool (mock-ai-agent)

Data Flow

1. Fetch:  cupertino fetch --type docs
   ↓
   WKWebView → HTML → Markdown → disk (~/.cupertino/docs/)

2. Save:   cupertino save
   ↓
   Markdown files → SQLite FTS5 index (~/.cupertino/search.db)

3. Serve:  cupertino serve
   ↓
   MCP Server (stdio) ← JSON-RPC ← Claude Desktop
   ↓
   DocsResourceProvider + CupertinoSearchToolProvider

Key Design Principles

• Swift 6.2 Concurrency: 100% strict concurrency checking with actors and async/await
• Value Semantics: Immutable structs by default, Sendable conformance
• Actor Isolation: @MainActor for WKWebView, actors for shared state
• Explicit Dependencies: No singletons, clear dependency injection
• Separation of Concerns: Crawling → Indexing → Serving as distinct phases

Development

Build System

# Show all available commands
make help

# Common tasks
make build                  # Build release binaries
sudo make install           # Install to /usr/local/bin
sudo make update            # Rebuild and reinstall
make test                   # Run all tests
make clean                  # Clean build artifacts

# Development workflow
make test-unit              # Fast unit tests only
make test-integration       # All tests (includes network calls)
make format                 # Format code with SwiftFormat
make lint                   # Lint with SwiftLint

Testing

Test Suite:

• 698 tests across 73 test suites
• ~35 seconds duration
• Includes unit tests, integration tests, and formatter tests

Test Categories:

• Web Crawl Tests - Real Apple documentation fetching
• Fetch Command Tests - Package/code downloading
• Save Command Tests - Search index building
• MCP Tests - Server health, tool/resource providers
• Core Tests - Search, logging, state management

Logging

Cupertino uses os.log for structured logging:

# View all logs
log show --predicate 'subsystem == "com.cupertino"' --last 1h

# View specific category
log show --predicate 'subsystem == "com.cupertino" AND category == "crawler"' --last 1h

# Stream live logs
log stream --predicate 'subsystem == "com.cupertino"'

Categories: crawler, mcp, search, cli, transport, pdf, evolution, samples

Performance

Operation	Time	Size
Build CLI	10-15s	4.3MB
Crawl 301,000+ pages	12+ days	2-3GB
Swift Evolution	2-5 min	429 proposals
Swift.org docs	5-10 min	501 pages
Build search index	2-5 min	~160MB
Search query	<100ms	-

Why Crawling Takes 12+ Days

The crawler respects Apple's servers with a 0.5 second default delay between each request (configurable):

• 301,000 pages × 0.5s = 150,500 seconds (~42 hours minimum)
• Plus page rendering, parsing, and saving time
• Crawl must reach depth 21+ to get all documentation
• Total: ~12+ days for initial full crawl

Use cupertino setup to download pre-built databases instead (~30 seconds).

This is a one-time operation. Incremental updates use change detection to skip unchanged pages and complete much faster.

Example Use Cases

1. Offline Documentation Archive

# Download everything for offline access
cupertino fetch --type docs --max-pages 15000
cupertino fetch --type evolution
cupertino save

2. Framework-Specific Research

# Just SwiftUI documentation
cupertino fetch --type docs \
  --start-url "https://developer.apple.com/documentation/swiftui" \
  --max-pages 500

3. AI-Assisted Development

# Serve documentation to Claude
cupertino serve

# Then ask Claude: "How do I use @Observable in SwiftUI?"

4. Custom Documentation Workflows

# Multiple sources with custom paths
cupertino fetch --type docs --output-dir ~/docs/apple
cupertino fetch --type evolution --output-dir ~/docs/evolution
cupertino save --base-dir ~/docs --search-db ~/docs/search.db
cupertino serve --docs-dir ~/docs/apple --search-db ~/docs/search.db

Documentation

• DEVELOPMENT.md - Build, test, contribute, and release workflow
• docs/ARCHITECTURE.md - Technical deep-dives (Concurrency, MCP, WKWebView testing)
• docs/DEPLOYMENT.md - Homebrew distribution and CI/CD setup
• docs/commands/ - Command-specific documentation

Command Documentation

Each command has detailed documentation:

• docs/commands/fetch/ - Download documentation
• docs/commands/save/ - Build search indexes
• docs/commands/serve/ - Start MCP server
• docs/commands/search/ - Search documentation from CLI
• docs/commands/doctor/ - Check server health

Contributing

Issues and pull requests are welcome! I'd love to hear how you're using Cupertino with your AI workflow.

For questions and discussion, use GitHub Discussions.

I prefer collaboration over competition — if you're working on something similar, let's find ways to work together.

Don't hesitate to submit a PR because of code style. I'd rather have your contribution than perfect formatting.

By participating in this project you agree to abide by the Contributor Covenant Code of Conduct.

For development setup, see DEVELOPMENT.md.

Project Status

Version: 0.9.1 Status: 🚧 Active Development

• ✅ All core functionality working
• ✅ 93 tests passing (100% pass rate)
• ✅ 0 lint violations
• ✅ Swift 6.2 compliant with 100% strict concurrency checking
• ✅ All production bugs resolved

License

MIT License - see LICENSE for details

Acknowledgments

• Built with Swift 6.2 and Swift Package Manager
• Uses swift-argument-parser for CLI
• Implements Model Context Protocol specification
• Inspired by the need for offline Apple documentation access

Related Repositories

• cupertino-desktop - Native macOS desktop app with graphical interface
• cupertino-docs - Pre-built documentation archive for quick installation
• cupertino-sample-code - Apple sample code repository mirror

The docs and sample-code repositories will be used by the planned make install (full) command (see #52), providing pre-built documentation and sample code to avoid the initial 20+ hour crawl.

Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions

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Note: This tool is for educational and development purposes. Respect Apple's Terms of Service when using their documentation.