In our previous post “Reinventing how .NET Builds and Ships”, Matt covered our recent overhaul of .NET’s building and shipping processes. A key part of this multi-year effort, which we called Unified Build, is the introduction of the Virtual Monolithic Repository (VMR) that aggregates all the source code and infrastructure needed to build the .NET SDK. This article focuses on the monorepo itself: how it was created and the technical details of the two-way synchronization that keeps it alive.