The fact that Microsoft is working on some kind of device with a foldable, dual-display feels almost like an unstated truth at this moment, with far too many leaks to count. This device, often referred to as the Surface Phone or Andromeda, may feature a 360-degree hinge according to information found by the erudite WalkingCat.
Tracking new APIs added by Microsoft in the latest build released to Windows Insiders, the Microsoft enthusiast was able to spot the addition of APIs that can track different "hinge states", being 5 in number. They are: closed, presumably meaning the two screens are facing each other; convex, which might refer to the two screens being open but at less than 180-degrees; flat; concave, with both screens being open at more than 180-degrees à la tent mode; and full, likely representing a full 360-degree rotation of the hinge.
enum Windows.System.Preview.HingeState
— WalkingCat (@h0x0d) June 28, 2018
{ Unknown, Closed, Concave, Flat, Convex, Full } ? pic.twitter.com/DieWl4fa52
Of course, the first 4 modes already exist in some capacity or the other among modern 2-in-1 Windows PC, with the 360-degree rotation being the most interesting of the bunch. Giving Windows the ability to detect these different modes would allow developers to track how the user may be handling their device, and modify their software to respond accordingly. What use cases Microsoft may be working on for the "full" configuration, however, we can only guess at this point.
The APIs don"t, of course, make any mention of Andromeda by name but that is the most likely target for this functionality. We will find out soon enough though, as the company is expected to finally announce the device at some point this year.
Source: WalkingCat (Twitter) via MSPoweruser