Microsoft used Build on June 2 and 3 to preview Rayfin, an open-source SDK and command-line tool that can generate a typed, governed backend and send it straight to Microsoft Fabric. With one CLI command, the project moves from code to a managed service, where app data lands in OneLake by default.
The announcement lands at a moment when developers are leaning harder on coding agents to spin up apps quickly, but still spending far longer getting those apps ready for production. Rayfin is aimed at that bottleneck. It is built to create the plumbing before the first user ever sees the product: database setup, authentication, storage and access policies all come bundled into the backend it generates.
That matters because the people building with agents are often left stitching together the pieces that make software safe to run in the real world. Microsoft is trying to pull that work into Fabric, where the app, its data and its services stay inside the user's own tenant under identity, network and governance controls that are already in place. The pitch is simple enough: if the backend is governed from the start, teams spend less time on the handoff between a working demo and something they can actually ship.
Rayfin is not finished yet. Microsoft said it is in preview, and it did not give a date for general availability. That leaves the central question open for developers watching Build closely: whether the tool becomes the default route for getting agent-built apps into production, or whether teams will still treat it as a promising shortcut that needs more time before it can replace the slower, familiar path.
