BuildFeed is a popular 3rd party Twitter account and website that does one thing, scours the internet (we think, or who-knows-where) for the latest Microsoft build numbers. These largely unreleased build numbers don't have much if any other information about them, but it can be an interesting source of conjecture as to the next Windows Insider or Xbox Insider build number, for example, and can sometimes shed some new light as to what's going on behind closed doors at Microsoft.
Over the weekend, BuildFeed has posted a number of new numbers with some interesting new information. For the first time to our knowledge, has included some builds marked with OneCore and WCOS, the Windows Core Operating System naming that Microsoft is reportedly working on to power "Andromeda," or what at one time was known as Surface Phone, the Surface Hub 2, possibly HoloLens v2, and perhaps a lot more.
BuildFeed has also recently posted some other interesting info, along with what appear to be old build numbers, perhaps newly captured, including a build referring to "shell devices foldable," a 19H1 version, and even something called "rs_fun_pkg"
— BuildFeed (@buildfeed) January 14, 2019
Having these builds show up on BuildFeed is interesting, but it may not be much more than that. For one thing, we don't have any reliable information as to the source of these posted build numbers, it could be that BuildFeed has just gained new access to what internally is an ongoing series of OneCore and other builds (and we suspect this is the case). Still, having the builds in the 19H1 numbering sequence is noteworthy, and expectations are to hear a lot more about OneCore in the coming year. Whether this is just a peek through a keyhole or an important new development is unclear at this point, but we'll be keeping a close watch on BuildFeed and beyond, so stay tuned to OnMSFT.com.