Duology

Claude Code skills for designing, building, testing and shipping apps on iPhone Duo.

Your agent learned iOS before the iPhone Duo existed. Duology teaches it the rest.

Quick start · What's inside · Patterns · Recipes · Proof · FAQ · Roadmap

/plugin marketplace add Kimeur/duology

[!IMPORTANT] v0.4 is out (29 October 2026): for apps that already ship. duo-migrate moves an app to Xcode 27.1 and the scene life cycle step by step, duo-app-store makes the App Store screenshots of both displays, and /duo-ship checks the April 2027 App Store rules before you submit: it runs your app in every pose, and the duo-pose-tester agent reports each failure with its screenshot. Plus a sixth recipe, recipe-kids-learning. 33 skills in 5 plugins, 6 commands and 2 agents, checked on Xcode 27.1 and the iPhone Duo simulator. Checks on a real iPhone Duo and published test results come next. Duology is built in the open: the full pack of 36 skills is planned for v1.0 in January 2027. Star or watch the repo to follow along. See the roadmap and the release notes.

[!NOTE] Duology is a community project. It is not affiliated with, endorsed by or sponsored by Apple Inc. iPhone is a trademark of Apple Inc. Every API claim links to Apple's own documentation in reference/sources.md.

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The problem

iPhone Duo is in stores from 23 October 2026. It has a 5.4″ outer display, a 7.6″ inner display and a fold. Coding agents were trained before it existed, so when you ask one to "make this work on Duo" it writes code Apple tells you not to write:

• it measures UIScreen.main.bounds, which is ambiguous on a phone with two displays;
• it branches on device orientation or userInterfaceIdiom and treats "regular width" as "iPad";
• it puts buttons and text where the phone folds;
• it rebuilds the screen when you unfold, so you lose your scroll position, your typing or your video;
• it designs one screen and stretches it, instead of a layout for each way people hold the phone.

Apple published the rules in six Tech Talks, a HIG page and the iOS 27.1 SDK. Duology turns them, plus what we learned shipping a real Duo app, into skills Claude Code loads when it needs them.

How Duology fixes it

1. It knows the device. Size classes, reserved regions, ArrangementView, vertical bars and the hinge. Each fact is checked against the iOS 27.1 SDK. Scenes and windows have their own skill (v0.2), and so do the cameras (duo-camera, v0.3).
2. It designs, not just compiles. Eight named layout patterns, state that survives fold and unfold, and two people on one screen, each with SwiftUI code. v0.2 adds design tokens, guidance for each pose, fold transitions, thumb reach and accessibility on both displays.
3. It builds whole apps. A recipe creates a project that builds and runs on the iPhone Duo simulator. All eight are ready: a two-player game, a finance dashboard, a media player, a reader, a shop, a learning app for young children, notes with on-device AI summaries and a camera studio.
4. It checks its own work. duo-lint finds code Apple warns against. /duo-audit adds a 15-point design checklist on screenshots from the simulator. /duo-poses (v0.2) screenshots your app closed, open, in book pose and in tabletop, and /duo-review hands those frames to a design review agent. /duo-ship checks the App Store rules for Duo before you submit, with a pose test agent and screenshots of both displays.

Quick start

You need: a Mac with Apple silicon, Xcode 27.1 (27A9275 or later) and Claude Code.

/plugin marketplace add Kimeur/duology
/plugin install duology@duology

Add the other plugins when you need them:

/plugin install duology-design@duology
/plugin install duology-recipes@duology
/plugin install duology-ship@duology
/plugin install duology-features@duology

duology-recipes and duology-ship need duology, which gives them /duo-doctor. duology-design and duology-features install on their own, but their skills point to duology's skills (duo-layout, duo-continuity, duo-scenes), so install duology first. duology-features adds the iOS 27 features: Foundation Models, App Intents, the camera, media, reading, games, the iOS 27 SwiftUI changes, and widgets, Live Activities and Controls.

Restart Claude Code, then check your setup:

/duo-doctor

This is the beginning of the README. Read the rest at the original. Read the full README ↗