Every new physical move the iPhone Duo hands your app, what it does, what it apparently feels like, and things you could actually build on each one.

A companion to The Diff's idea post: How to stand out with Duo. The short version: there's a way to build your app's iBeer or Pixel Pals inside every one of these. They're prompts to steal, not prescriptions. Swap in your own product, your own users, your own weirdness.

I don't have a Duo yet, so the "feels like" column is assembled from hands-on coverage and Apple's own sessions rather than my own thumbs.

Move	What it does	What it feels like
Unfold	UI blurs and stretches from the 5.4" outer screen to the 7.6" inner one. Content stays locked in space while the phone reorients around it. Audio retunes as the speakers separate.	The "work of art" clip everyone shared. The hello. The opening moment that makes people want to open you again.
Fold	The same transition in reverse. The system nudges any interactive control off the hinge as it closes.	The putting-it-away moment. Nobody has built a goodbye for it yet.
Tent pose (45–120°)	The phone stands on its own. StandBy runs without being plugged in: clock, photos, widgets, controls.	A tiny display on your desk, your nightstand, the kitchen counter.
Laptop pose (~90°)	Content on the top half, controls on the bottom half. Netflix moves its playback controls down here.	Hands-free video and calls. A phone that behaves like a tiny laptop on a tray table.
Flat open	The full 7.6" canvas. Split View on iPhone for the first time, including two windows of the same app.	An iPad Mini in your pocket. Slack shows a whole workspace, Zoom stacks the shared doc over the faces.
Outer to inner handoff	Start on the small screen, unfold, continue in place with no reload and no lost position.	The unfold-to-see-more hook.
Hinge as a control	A new API reports closed, partially open or fully open, plus a continuous angle. Apple's own demo is a guitar whammy bar that bends pitch as you fold.	The phone is a physical input now. This is the weird one.
Second screen accessory	While the inner screen runs your app, the outer screen shows something else entirely to the person in front of you. Apple's demo is a teleprompter.	Two people, two screens, one phone.

The build ideas

✨ Unfold

A hello that changes. The first thing revealed isn't your home screen, it's the one thing that's different since last time. What's new, the streak, who's waiting.
Put the payoff behind the fold. Whatever they opened the app for lives on the inside. The balance, the match, the result. Opening the phone becomes opening a box.
Continue, don't reload. If they were doing something outside, expand it in place. That's the whole Netflix Clips trick.
Own the three seconds. The transition is screen time nobody is using yet. A logo bloom, a colour wash, a sound.

The test: would a stranger understand it on mute, on a loop, with no caption?

👋 Fold

A goodbye. One line on the outer screen as it closes. Apps are obsessed with the open and ignore the close.
Closing as a commit. Fold and the thing happens. Save, send, end the session, log the workout, start sleep tracking. The gesture is the button.
Fold to hide. A banking app that shows nothing on the outside is making a promise you can see.
The stamp. A streak tick or a day-complete mark that lands as the screen goes dark.

This is the half of the gesture nobody has claimed, and it happens exactly when your user is deciding whether the thing was worth it.

⛺ Tent pose

Ambient mode. Your app as a desk object. No charger needed now, which is the change. What's worth looking at from across a room?