iphone-duo-skills

iPhone Duo Skills

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Image © Apple Inc., from the iPhone Duo developer page, used for identification. Not affiliated with or endorsed by Apple.

Agent skills for building iOS apps on iPhone Duo — Apple's first foldable iPhone, announced September 9, 2026.

Apple's developer material for iPhone Duo is now six Tech Talk videos, the Designing for iPhone Duo HIG page, the Prepare checklist, and the API reference. The last two landed after this repo started — the API reference corrected three claims, and the Prepare guide added several more. Both passes are reflected here.

These skills distill all of it into structured guidance an agent can act on, plus reference sheets for device facts and the full API surface.

Install

npx skills add mirzaaghazadeh/iphone-duo-skills

Installs all eleven. The CLI detects your agent — Claude Code, Cursor, Copilot, Gemini and others — and puts them where that agent looks.

Useful flags:

# just one skill
npx skills add mirzaaghazadeh/iphone-duo-skills --skill iphone-duo-readiness

# user-level instead of project-level
npx skills add mirzaaghazadeh/iphone-duo-skills --global

# see what's in here without installing
npx skills add mirzaaghazadeh/iphone-duo-skills --list

To try a skill without installing it at all:

npx skills use mirzaaghazadeh/iphone-duo-skills@iphone-duo-readiness

Manual install

git clone https://github.com/mirzaaghazadeh/iphone-duo-skills.git
cp -r iphone-duo-skills/skills/* ~/.claude/skills/

Or project-level, into .claude/skills/ in a repo.

Each skill is a self-contained SKILL.md with YAML frontmatter, so it also works anywhere that reads plain Markdown instructions. Restart the session and the skills appear; invoke one by name or just describe the task.

The skills

Which skills apply to your stack

Native iOS — SwiftUI or UIKit. Start with iphone-duo-readiness, which routes you to the rest. The five Swift-focused skills name real iOS 27.1 APIs you can call directly; iphone-duo-design-review applies whatever you build in.

Flutter. Read iphone-duo-flutter first, then iphone-duo-design-review — the design guidance is framework-neutral and applies unchanged. Skim iphone-duo-adaptive-layout for the reasoning behind reserved regions and displacement; the concepts transfer even though the code doesn't.

React Native or Expo. Same shape: iphone-duo-react-native, then iphone-duo-design-review, then iphone-duo-adaptive-layout for background.

Any framework, if you capture photo or video. iphone-duo-camera matters regardless of stack, because the two front cameras and the "which way is this camera facing" problem are AVFoundation-level facts. Cross-platform apps hit them through whatever camera plugin they use, or through their own bridge.

Games — Unity, Unreal, Godot, SpriteKit, Metal. Read iphone-duo-games. Games sidestep most of the UI guidance but not resizing, and the fold is a genuine hazard for on-screen touch controls.

Capacitor, Ionic or another web view. Read iphone-duo-capacitor first, then iphone-duo-design-review. The twist there is that the standard web APIs for this exist but are flagged off in a WKWebView, so the fold has to come from the native side even though the CSS for it is specified.

Kotlin Multiplatform, .NET MAUI and friends. No dedicated skill, but the pattern from the Flutter and React Native skills carries over directly: everything is either resize and safe-area handling you can do in your existing layer, or a native bridge to the iOS 27.1 APIs. Read whichever cross-platform skill is closer to your setup, plus iphone-duo-design-review.

Cross-platform reality check. Neither Flutter nor React Native supports iPhone Duo yet. Flutter's MediaQuery.displayFeatures is documented as populated only on Android, so it returns an empty list here; React Native has no fold API at all. Both skills split what works today from what needs a native bridge, so you don't lose an afternoon hunting for an API that isn't there.

Reference

• reference/device-facts.md — displays (pixels, ppi, points), dimensions, silicon, cameras, poses, and the size-class table
• reference/api-index.md — every announced API by job, with framework and minimum SDK
• reference/sources.md — every source, linked

What actually matters on this device

If you read nothing else:

iPhone Duo is not a new idiom — it's a wider continuum of sizes. Every bug in a foldable port comes from an app asserting something fixed (this idiom, this orientation, this screen, this width, this symmetric inset), and every fix replaces that assertion with a question about the space available right now.

Diagram by this project. The underlying behavior is documented across Apple's iPhone Duo Tech Talks and Designing for iPhone Duo; see reference/sources.md.

Three concrete consequences:

1. The inner display ignores your supported interface orientations. Branch on size class, never on orientation or idiom.
2. UIScreen.main is ambiguous here and slated for deprecation. Use the environment, the trait collection, or the scene's bounds.
3. Safe areas are asymmetric. Any math shaped like width - safeAreaInsets.left * 2 is a defect.

And the highest-leverage single change: build against the iOS 27.1 SDK. It's the gate for edge-to-edge content, vertical bars, reserved regions and arrangements.

Accuracy

Every technical claim traces to Apple's Tech Talks, the Designing for iPhone Duo HIG page, the published API reference, or the Newsroom announcement.

Verified against Apple's API reference on 25 September 2026. The symbol docs are now live, so the signatures in reference/api-index.md come from them rather than from the Tech Talk sessions. That pass corrected three things that had been wrong:

• The direction coordinator's change handler receives an AVCaptureDeviceDirectionMap, not an AVCaptureDeviceDescriptor — it hands you arrays of forward- and backward-facing descriptors to choose from.
• The UIKit arrangement mutators take an animated: parameter. (It defaults to false, the October pass found, so the Tech Talks' shorter calls compile — they just don't animate.)
• toolbarVerticalEdge reports the system's preferred edge whether or not a vertical bar is visible — it isn't a "are items vertical right now" flag.

A second pass on 27 September 2026 covered the hinge types and the SwiftUI reserved-region query, and corrected three more:

• UIKit's UIHinge.angle is in radians, and UIHinge.Status has a fourth case, .unknown. SwiftUI's DeviceHinge.Status is a struct, not an enum.
• The SwiftUI reservedRegions query takes a layoutDirectionBehavior: parameter (default .mirrors).
• A reserved region's frame already includes its margins — they aren't extra padding to add around it.

A third pass on 23 October 2026, after Apple expanded the reserved-region and arrangement pages into full articles, settled one question and opened another:

• The region query returns only active regions by default. The September reference had read otherwise; it now agrees with the Tech Talks.
• The Tech Talk says a flat fold is inactive with zero width; the reference and Group Lab Day 3 now say an inactive region keeps a frame you can leave room for ahead of time. The skills follow the later sources, with a note to check the frame in the simulator.
• A split arrangement shows only its primary view on a closed iPhone Duo held in landscape, and along any axis you excluded.

A fourth pass on 30 October 2026 read Registering a camera capture accessory on iPhone Duo, which the docs watcher had been looking for at the wrong path, and corrected one more:

• UIKit has no CameraCaptureAccessory. It registers a UISceneAccessory.cameraCapture(sceneConfiguration:userInfo:) on the view controller and gets back a UISceneAccessoryRegistration to observe and toggle.

A fifth pass on 6 November 2026 diffed every page the watcher flagged against an archived copy. Apple had only reordered text or added links, but the pass filled two gaps:

• toolbarVerticalEdge is nil only where the system never places a vertical bar. The bar keeps its physical side in right-to-left languages, so its .leading / .trailing value changes with the locale.
• Tech Talk 111465 now links Supporting device rotation in your camera app. A rotation coordinator is bound to one camera, so each camera switch a fold