Windows 10 preview build 18917 has given developers a peek into Microsoft's plans to separate the OS' Shell from the rest of the system. Under the new methodology, the company would make Shell UI parts like the Action Center, taskbar, and Start menu independently updatable.
Twitter's Albacore found evidence of this via a ‘Shell Update Agent', which he says “is capable of obtaining and updating the shell on demand”.
It's referred to as a PackageFamilyName, which Albacore believes is enough proof to discern it will be a separate packaged component that could even be shipped inside an Appx. This component is associated with a mechanism called Undocked Shell.
Accommodating Windows Core OS
Those who have been closely following the rumor mill will note that this is a step towards Windows Core OS, an unannounced evolution of the platform that's turning a poorly kept secret.
Core OS is reportedly a modular version of Windows, so it makes perfect sense that we're seeing this separation now. The version can pull different Shells for different form-factors, with say, a modified taskbar and start menu setup for foldables or HoloLens.
Even so, it's clear these additions are in the early days when it comes to public builds. Albacore was able to call a function from ShellUpdateAgent called StartInternalPackageAcquistion, but it only returned a placeholder UX package for the Action Center.
It's worth noting that this build is a preview of the Windows 10 release for 20H1, so that's to be expected. It's unlikely to launch until May next year, which gives plenty of time to push more changes.