Duo Fold Test

Open, half fold and close the phone. Every change is logged and kept across closes. Clear log keeps the sizes it has learned; Forget sizes resets them.

Best guess

…

APIs

Device Posture
Viewport Segments
CSS posture query
foldedcontinuousno match
An API is missing. On the phone, go to Settings > Apps > Safari > Advanced > Feature Flags, turn on Device Posture API and Viewport Segments API, then fully close Safari and reload this page.

Live

Posture
Window (inner)
Visual viewport
Screen
Pixel ratio
Orientation
Visibility
Largest seen
Segments
Screens seen
Segment rects

Try this

  1. Start with the phone open flat for a few seconds.
  2. Fold it halfway, like a laptop, and hold.
  3. Close it fully, wait about 10 seconds, then open it again.
  4. Tap Copy log and paste it back.

Event log