🍎📚 Cupertino

June 9, 2026 · View on GitHub

Apple documentation CLI for humans and MCP server for AI agents.

Cupertino is a CLI for human developers and an MCP server for AI agents. Both surfaces use the same local catalog of Apple documentation, Swift packages, sample code, Human Interface Guidelines, Swift Evolution proposals, and Swift.org pages.

Cupertino Demo

Latest: v1.3.0 (2026-05-31): per-source database bundle, read-only databases. The Apple documentation slice carries 351,505 documents / 240,543 symbols across 420+ frameworks, alongside the HIG, archive, Swift Evolution, Swift.org, Swift Book, package, and sample-code DBs. Release notes · CHANGELOG · Roadmap · live dashboard at https://cupertino.aleahim.com/. Follow updates on X: @cupertinomcp.

If Cupertino is useful to your work with Apple docs or AI agents, consider sponsoring its development. Sponsorship helps keep releases, documentation, and the Apple/Linux tooling around it moving.

What is Cupertino?

Cupertino is a local, structured 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 fast, searchable SQLite FTS5 databases with field-weighted BM25 (BM25F) ranking and AST-extracted symbol columns
Runs as a terminal CLI for developers who want fast local search, read, doctor, and setup commands
Serves the same corpus to AI agents like Claude, ChatGPT, Codex, Cursor, and Copilot via the Model Context Protocol
Provides offline access to 351,505 Apple documentation pages / 240,543 Apple-doc symbols across 420+ frameworks, plus the HIG, archive, Swift Evolution, Swift.org, Swift Book, package, and sample-code slices (v1.3.0 bundle)

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: the same query always returns the same results
Local control: own your documentation, inspect the database, script workflows
Dual-consumer design: use it directly at the terminal or wire it into an MCP-capable AI client

Installation

Requires macOS 15+ (Sequoia) and ~4.2 GB free disk for the full v1.3.0 bundle (compressed download ~742 MB). Building from source additionally needs Swift 6.3+ and Xcode 26+ (use xcrun swift build, not bare swift).

One-command install (recommended): downloads a signed, notarized universal binary to /usr/local/bin and fetches the databases:

bash <(curl -sSL https://raw.githubusercontent.com/mihaelamj/cupertino/main/install.sh)

Homebrew:

brew tap mihaelamj/tap
brew install cupertino
cupertino setup            # download the pre-built databases

Build from source:

git clone https://github.com/mihaelamj/cupertino.git
cd cupertino
make build                 # release binary (or: cd Packages && swift build -c release)
sudo make install          # install to /usr/local/bin
cupertino setup            # download the pre-built databases

The Homebrew path on Apple Silicon installs to /opt/homebrew/bin/cupertino; Intel and manual installs use /usr/local/bin/cupertino. Run which cupertino to confirm your path. See docs/DEPLOYMENT.md for distribution and CI/CD notes.

Quick start

cupertino setup                                  # download pre-built databases (~30s)
cupertino search "NavigationStack" --limit 5     # search from the terminal
cupertino read "apple-docs://swiftui/navigationstack" --source apple-docs
cupertino doctor                                 # check local database health
cupertino serve                                  # start the MCP server (also the default command)

Prefer to build the index yourself instead of downloading it? cupertino save --remote streams the corpus from GitHub and rebuilds locally, and cupertino fetch --source <name> crawls a single source from the original site. See docs/commands/ for every command, flag, and the slower self-hosted paths.

Two surfaces, one catalog

A terminal search prints a human-friendly result with scores and follow-up commands:

$ cupertino search "NavigationStack" --format text --limit 2
Question: NavigationStack
Searched: apple-docs, samples, swift-evolution, swift-org, swift-book, packages

======================================================================
[1] NavigationStack  •  source: apple-docs  •  score: 0.0324
    apple-docs://swiftui/navigationstack
----------------------------------------------------------------------
A view that displays a root view and enables navigation to additional views.

▶ Read full: cupertino read "apple-docs://swiftui/navigationstack" --source apple-docs

💡 Narrow with --source <name>: apple-docs, samples, hig, apple-archive, swift-evolution, swift-org, swift-book, packages
💡 Filter by platform: --platform iOS --min-version 16.0  (or macOS / tvOS / watchOS / visionOS)

The same query over MCP returns a structured tool result an AI client can read, cite, and follow with read_document:

{
  "name": "search",
  "arguments": { "query": "NavigationStack", "source": "apple-docs", "limit": 2 }
}

Demo: Watch on YouTube.

Use with AI agents

Claude Code registers Cupertino globally with one command:

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

Claude Desktop, OpenAI Codex, Cursor, VS Code (Copilot), GitHub Copilot for Xcode, Zed, Windsurf, and opencode are all covered with copy-paste config in docs/mcp-clients.md. Cupertino can also run as a stateless CLI Agent Skill with no server: see docs/agent-skill.md.

What you get

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
...	...
420+ frameworks	351,505

Core features

Multi-source documentation

Apple Developer Documentation (~351,505 indexed pages): JavaScript-aware rendering via WKWebView, HTML-to-Markdown conversion, smart change detection
Swift Evolution (~429 proposals) and Swift.org (~501 pages): GitHub- and site-based fetching in Markdown
Swift package metadata: packages.db ships 185 packages with full source, stars, licenses, deployment-target platforms, and authored swift-tools-version
Apple Sample Code (619 projects, 18,000+ indexed Swift files): fetched from Apple's CDN or the GitHub mirror, full-text searchable
Apple Archive legacy guides (~368 pages in v1.3.0): pre-2016 conceptual docs (Core Animation, Quartz 2D, Core Text); included in default fan-out with a lower rank weight, or searchable alone with --source apple-archive
Human Interface Guidelines: Apple's design guidelines across iOS, macOS, watchOS, visionOS, and tvOS

Full-text search engines

BM25F ranking: SQLite FTS5 with field-weighted BM25 (Robertson/Zaragoza/Taylor 2004) over a 9-column index (uri, source, framework, language, title, content, summary, symbols, symbol_components). Title 10×, AST-extracted symbols 5×, summary 3×, framework 2×, CamelCase-split components 1.5×.
AST-aware: a Swift extractor pulls identifiers from every embedded code block and the page declaration into a symbols column, so a query like Task ranks the Swift Task struct above prose mentions of "task".
smart-query: cupertino search (and the Search.SmartQuery API) fans the question across every source in parallel and fuses per-source rankings via reciprocal rank fusion (RRF, k=60, Cormack/Clarke/Büttcher 2009); one dead source never takes the whole query down.
Porter stemming, framework + platform-availability filtering, snippet generation, sub-100 ms queries.
Databases must live on a local filesystem (SQLite is unreliable on NFS/SMB).

Model Context Protocol server

Resources: direct page access via apple-docs://{framework}/{page}, swift-evolution://{proposal-id}, hig://{category}/{page}
search: unified full-text search across every indexed source. Parameters: query (required), source, framework, language, include_archive, limit, and the min_ios/min_macos/min_tvos/min_watchos/min_visionos/min_swift platform filters (AND-combined; malformed values are rejected at the boundary with a clear error frame). Replaces the pre-#239 per-source tools.
list_frameworks, list_documents, list_children, read_document (format: json for agents, markdown for humans)
Sample-code tools: list_samples, read_sample, read_sample_file; pass format=json for typed project/file payloads
AST-powered symbol tools (#81): search_symbols, search_property_wrappers, search_concurrency, search_conformances, search_generics, get_inheritance; pass format=json for typed symbol rows and title-bearing inheritance trees
Desktop boundary: desktop UI code consumes these backend/tool contracts. It must not open SQLite databases directly or duplicate Cupertino's read engine.

See docs/tools/ for per-tool documentation.

Intelligent crawling

Resumable from saved state, change-detection to skip unchanged pages, a respectful 0.05 s default delay (configurable), automatic URL-queue deduplication, and priority queues so important content is fetched first.

How it works

Cupertino uses an ExtremePackaging architecture: 48 in-tree strict-producer SPM targets with explicit import contracts, plus the external CupertinoDataEngine package. See docs/ARCHITECTURE.md for the full breakdown and docs/package-import-contract.md for the strict per-target import rules.

flowchart TB
  Foundation["Foundation tier<br/>SharedConstants · LoggingModels · MCPCore · MCPSharedTools · Resources"]
  Infrastructure["Infrastructure<br/>ASTIndexer · Diagnostics · Logging"]
  Producers["Strict producers<br/>Crawler · Core · Search · SampleIndex · Services<br/>AppleConstraintsKit · Availability · Cleanup · more"]
  Operations["Operation packs<br/>Distribution setup · Diagnostics doctor · Indexer save · Ingest fetch"]
  MCP["MCP layer<br/>MCPSupport · MCPClient · SearchToolProvider"]
  FrontDoors["Front doors<br/>CLI cupertino · TUI cupertino-tui"]
  External["External packages<br/>CupertinoDataKit · CupertinoDataEngine<br/>SwiftMCPCore · SwiftMCPClient"]

  Foundation --> Infrastructure
  Foundation --> Producers
  Producers --> Operations
  Producers --> MCP
  Operations --> FrontDoors
  MCP --> FrontDoors
  External --> Producers
  External --> MCP

Data flows through three distinct phases:

flowchart LR
  Fetch["Fetch<br/>cupertino fetch --source apple-docs"]
  Raw["Raw corpus<br/>DocC render JSON, Markdown,<br/>sample archives, package sources"]
  Save["Save<br/>cupertino save --all"]
  Bundle["v1.3.0 catalog bundle<br/>apple-documentation.db · hig.db · apple-archive.db<br/>swift-evolution.db · swift-org.db · swift-book.db<br/>apple-sample-code.db · packages.db"]
  Services["Read services<br/>search · read · list · semantic tools"]
  CLI["Terminal CLI<br/>human-readable text / JSON / markdown"]
  MCP["MCP server<br/>typed tool responses over stdio"]
  Agents["AI agents<br/>Claude · Codex · Cursor · Copilot · more"]

  Fetch --> Raw --> Save --> Bundle --> Services
  Services --> CLI
  Services --> MCP --> Agents

Key design principles: Swift 6.3 with 100% strict concurrency checking, value semantics and Sendable by default, actor isolation (@MainActor for WKWebView), explicit dependency injection with no singletons, and a hard separation of Crawling → Indexing → Serving.

Published packages

Cupertino factors reusable, independently-versioned Swift packages out of the monorepo. Each is its own public repository and is consumed by tag:

Package	Repo	What it is
SwiftMCPCore	mihaelamj/SwiftMCPCore	Neutral MCP wire types (the JSON-RPC + protocol value types). Not cupertino-specific; a general MCP building block.
SwiftMCPClient	mihaelamj/SwiftMCPClient	Neutral, transport-injectable MCP client (`Client.MCP` seam, `MCPClient` actor, subprocess transport). Depends on SwiftMCPCore.
CupertinoDataKit	mihaelamj/CupertinoDataKit	Cupertino's public read contract: documentation/source reading, document browsing, symbol/code-intelligence reading, and sample-code reading protocols plus every value type they return. Protocols + value types only, zero implementation; cupertino's engine conforms server-side, and an embedded/in-process reader (e.g. an iOS app) conforms a different implementation. Cupertino's foundation tier re-exports it (`@_exported import CupertinoDataKit`).
CupertinoDataEngine	mihaelamj/CupertinoDataEngine	Cupertino's embedded read-only backend facade for app clients. The engine itself conforms to the public read/browse contracts and fans out across configured source, sample, and package readers. The current v0.2.6 slice keeps the opaque `Corpus` handle and aligns current-corpus opening with release bundles: sample code is opened through the sample reader, and packages stay on `packages.db`. UI code must not know the storage files exist.

See the current CupertinoDataEngine wiring diagram for the boundary between CupertinoDataEngine, in-tree CupertinoComposition, and downstream app clients. Mobile catalog installation is documented in docs/design/mobile-catalog-delivery.md, including app storage and the CatalogStore contract.

flowchart LR
  subgraph Apps["Downstream app clients"]
    Desktop["macOS / Linux desktop UI<br/>SwiftUI · AppKit · Qt"]
    Mobile["iPhone / iPad UI<br/>UIKit · SwiftUI"]
  end

  Backend["App backend interface<br/>CupertinoDataKit contracts"]
  Boundary["Contract boundary<br/>storage hidden from UI"]
  Engine["CupertinoDataEngine<br/>opaque Corpus handle"]
  Composition["CupertinoComposition<br/>cupertino-owned production wiring"]
  Internals["Cupertino internals<br/>source, sample, package readers<br/>schema checks, storage filenames"]
  CatalogStore["DownloadedCatalogStore<br/>free mobile catalog download"]
  AppSupport["Application Support/Catalogs<br/>not Documents, excluded from backup"]

  Desktop --> Backend
  Mobile --> Backend
  Backend --> Boundary --> Engine
  Composition --> Engine
  Engine --> Internals
  Mobile --> CatalogStore --> AppSupport --> Engine
  Boundary -.-> Internals

Roadmap

The canonical living roadmap is #183; the diagram below tracks epic progress at a glance.

Status legend:

flowchart LR
  done["Done"]:::done
  review["Review"]:::review
  active["Active"]:::active
  next["Next"]:::next
  partial["Partial"]:::partial
  todo["Todo"]:::todo
  classDef done    fill:#34C759,color:#FFFFFF
  classDef review  fill:#30B0C7,color:#FFFFFF
  classDef active  fill:#007AFF,color:#FFFFFF
  classDef next    fill:#5856D6,color:#FFFFFF
  classDef partial fill:#FF9500,color:#FFFFFF
  classDef todo    fill:#8E8E93,color:#FFFFFF

Epic progress:

flowchart TB
  subgraph Active["Active"]
    direction TB
    E1242["#1242 critical path"]:::active ~~~ E1262["#1262 desktop backend surface"]:::active ~~~ E1270["#1270 pre-UI readiness gate"]:::active ~~~ E1221["#1221 recrawl and resume"]:::active
  end

  subgraph Partial["Partial"]
    direction TB
    E1261["#1261 data engine extraction (opaque corpus shipped)"]:::partial ~~~ E1036["#1036 per-source DB split (#1061 left)"]:::partial ~~~ E191["#191 search quality and FTS"]:::partial
  end

  subgraph Planned["Planned"]
    direction TB
    E1228["#1228 semantic and vector search"]:::todo ~~~ E1223["#1223 declarative pluggability"]:::todo ~~~ E1222["#1222 Linux port"]:::todo ~~~ E769["#769 layer separation"]:::todo ~~~ E268["#268 MCP capability expansion"]:::todo ~~~ E266["#266 availability annotation v2"]:::todo ~~~ E190["#190 source expansion"]:::todo ~~~ E189["#189 TUI internal tracker"]:::todo
  end

  subgraph Closed["Closed"]
    direction TB
    E1227["#1227 distribution and discoverability"]:::done ~~~ E1226["#1226 docs and DocC"]:::done ~~~ E1225["#1225 diagnostics and logging"]:::done ~~~ E1224["#1224 CLI ergonomics"]:::done ~~~ E1220["#1220 v1.3.x bug sweep"]:::done ~~~ E943["#943 query batteries"]:::done ~~~ E919["#919 source and DB pluggability"]:::done ~~~ E893["#893 producer-backend split"]:::done ~~~ E673["#673 v1.2.x ironclad"]:::done ~~~ E503["#503 package-import purification"]:::done ~~~ E495["#495 GoF protocol DI"]:::done ~~~ E381["#381 dependency injection by default"]:::done ~~~ E251["#251 unify sources and databases"]:::done
  end

  Active ~~~ Partial ~~~ Planned ~~~ Closed
  classDef done    fill:#34C759,color:#FFFFFF
  classDef review  fill:#30B0C7,color:#FFFFFF
  classDef active  fill:#007AFF,color:#FFFFFF
  classDef next    fill:#5856D6,color:#FFFFFF
  classDef partial fill:#FF9500,color:#FFFFFF
  classDef todo    fill:#8E8E93,color:#FFFFFF

Pre-UI readiness gate:

flowchart TD
  release["#1268 current read surfaces green on main"]:::done
  source["CupertinoDataEngine v0.2.2 source-corpus reader"]:::done
  samples["v0.2.3 sample-reader construction"]:::done
  packages["v0.2.3 package-reader construction"]:::done
  bundle["v0.2.6 opaque release-corpus layout"]:::done
  ios["iOS build proof for complete closure"]:::done
  catalog["CatalogStoreAPI supplies opaque corpus handles"]:::done
  embedded["Live LocalEmbeddedBackend real-corpus smoke"]:::done
  smoke["#1269 repeatable release-corpus smoke"]:::done
  stores["Mobile catalog install via CatalogStore"]:::next
  ui["Begin native UI showcase work"]:::todo

  release --> source --> samples --> packages --> bundle --> ios --> catalog --> embedded --> smoke --> stores --> ui
  classDef done    fill:#34C759,color:#FFFFFF
  classDef next    fill:#5856D6,color:#FFFFFF
  classDef todo    fill:#8E8E93,color:#FFFFFF

Performance

Operation	Time	Size
`cupertino setup` (download pre-built bundle)	~30 s	~742 MB download, ~4.2 GB on disk
Build CLI	10–15 s	4.3 MB
Search query	<100 ms	n/a
Swift Evolution fetch	2–5 min	429 proposals
Swift.org fetch	5–10 min	501 pages
Build the full index from local JSON (`cupertino save --all`)	~12 h	~2.8 GB `apple-documentation.db` + per-source siblings
Full crawl of Apple docs from source (`cupertino fetch`)	~12 days	~404,000 raw pages → 351,505 indexed

The full crawl is slow by design: with the 0.05 s default delay, ~404,000 pages cost ~5.6 hours in delay alone, and WKWebView rendering, parsing, and saving per page dominate the rest, pushing wall-clock to ~12 days at depth 21+. This is a one-time operation, and incremental updates skip unchanged pages. Almost everyone should run cupertino setup instead and get the same corpus in seconds.

Development

make help                   # all available commands
make build                  # build release binaries
sudo make install           # install to /usr/local/bin
make test                   # run all tests
make test-unit              # fast unit tests only
make test-integration       # all tests (includes network calls)
make format                 # SwiftFormat
make lint                   # SwiftLint

Tests: the current full package suite reports 3,122 runtime tests across 501 suites from 351 Swift test files; parameterized @Test(arguments:) cases expand at runtime. Built on Swift Testing (@Test, @Suite, #expect) with withDependencies for injection, spanning unit tests, integration tests (real WKWebView against real Apple docs), and formatter tests.

Logging: structured os.log under the com.cupertino.cli subsystem (categories: crawler, mcp, search, cli, transport, evolution, samples, package-downloader, archive, hig).

log show --predicate 'subsystem == "com.cupertino.cli"' --last 1h
log stream --predicate 'subsystem == "com.cupertino.cli"'

MCP JSON-RPC wire traffic goes to stderr, not os.log, because stdout carries the protocol itself. Capture it with cupertino serve 2>/tmp/cupertino-mcp.log or your client's server-output panel. MCP lifecycle and diagnostic messages still log to os.log under the mcp category.

See CONTRIBUTING.md for the full build, test, and release workflow.

Documentation

CONTRIBUTING.md: build, test, contribute, and release workflow
docs/PRINCIPLES.md: engineering principles (lossless URIs, no content lost at the door, 10x scale headroom)
docs/ARCHITECTURE.md: technical deep-dives (concurrency, MCP, WKWebView testing)
docs/DEPLOYMENT.md: Homebrew distribution and CI/CD setup
docs/release/release-corpus-smoke.md: on-demand release-corpus smoke gate for repo-built binaries
docs/mcp-clients.md: per-client MCP setup (Claude, Codex, Cursor, VS Code, Zed, Windsurf, opencode, and more)
docs/agent-skill.md: use Cupertino as a stateless CLI Agent Skill (no server)
docs/commands/: command-specific documentation (fetch, save, serve, search, doctor, and more)
docs/tools/: MCP-tool-specific documentation
docs/roadmap-maintenance-protocol.md: maintainer roadmap update protocol

Project status

Released: v1.3.0 (2026-05-31): the per-source database bundle + read-only databases release. The unified search.db is split into 8 per-source databases shipped in rollback journal mode, so each opens read-only without an -shm sidecar and no query / read / serve connection can write or delete rows (#1194). databaseVersion is 1.3.0; cupertino setup downloads cupertino-databases-v1.3.0.zip (742 MB) carrying 351,505 documents / 240,543 symbols in apple-documentation.db (2.8 GB, user_version 18), plus packages.db (1.09 GB, 185 packages), apple-sample-code.db (192 MB), and the HIG / archive / evolution / org / book databases.

Previously: v1.2.1 (2026-05-23, maintenance + Source Independence Day), v1.2.0 "ironclad" (2026-05-20, search-quality release: rank-1 accuracy on canonical-lookup queries 52% → 92%), v1.1.0 (2026-05-14), v1.0.2 (2026-05-11). Full history in CHANGELOG.md.

✅ All core functionality working, all production bugs resolved at ship time
✅ 3,122 runtime tests across 351 Swift test files (501 suites)
⚠️ SwiftLint exits clean with 0 serious violations; warning-level lint debt and SwiftFormat drift remain in existing Swift files. Swift 6.3 with 100% strict concurrency checking.
✅ Search quality measured end-to-end (Phase 1 of docs/design/search-quality-eval.md): single-system baselines on 7 query classes + 3 paired v1.1.0 → v1.2.0 version-diff audits, all checked into docs/audits/

Contributing

Issues and pull requests are welcome, and 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 you agree to abide by the Contributor Covenant Code of Conduct. For development setup, see CONTRIBUTING.md.

cupertino-docs: pre-built documentation archive for quick installation
cupertino-sample-code: Apple sample-code repository mirror
cupertino-packages: Swift package source corpus indexed into packages.db
cupertino-symbolgraphs: Apple SDK symbol-graph corpus, the source for the apple-constraints.json and apple-conformances.json enrichment tables

License

MIT License, see LICENSE for details.

Support

Issues: GitHub Issues
Discussions: GitHub Discussions

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