According to BuildFeed, which regularly posts about new builds of Windows 10, the first build of a new SKU for foldable devices has been compiled. It comes with the build string rs_shell_devices_foldables.190111-1800, and it’s from the 19H1 development branch. The build number is 18313.1004.
The obvious conclusion to draw is that this is for Microsoft’s rumored Andromeda device. While the project was shelved back in July, it was originally for a foldable PC that could fit in your pocket. It’s likely now that it will be a larger device that’s slated for later on this year.
Foldable devices are definitely coming this year, but I feel like it might take a while for both users and device and software makers to figure out where, exactly, the fit into our lives.