Build 2026: Rayfin, databases, and agents for Microsoft Fabric take center-stage

Attendees gathered in-person and online for this year’s annual Microsoft Build event. This year’s event focused heavily on new tools like Rayfin, as well as improvements to existing Fabric and database capabilities.

Rayfin: A new approach to agents

The company launched Rayfin, a new open-source SDK and CLI, that is intended to close gaps in existing platforms that aren’t designed for agents or don’t meet enterprise security and governance requirements. Developers using Rayfin can work through GitHub-based workflows to define data models, set up access policies, and control backend logic.

Currently, Rayfin needs to be deployed directly with Fabric. Application data is routed into OneLake where it becomes available to the full Fabric data stack, with operational and real-time data, unified analytics, and AI engine integration. As part of the Rayfin launch, Microsoft is partnering with Replit, an AI coding platform, in a bid to help customers build enterprise apps. 

Microsoft General Manager Sachin Patney and Principal PM Architect Ben Zulauf demoed Rayfin capabilities in an Build session.

In the demo, Zulauf opened a VS Code CLI and walked through the setup, starting with basic project templates. He gave the project a name, adding needed files. Calling up Rayfin provisions the project in Fabric. “I can now run my development environment pointing to those resources. This is where it gets to be fun, because you can tell an agent to build the app you want to build.” 

Fabric Workspaces is where items and artifacts live. A new demo app database was present in Fabric along with a child SQL database. 

A member of the Replit team explained the integration of Rayfin and Fabric within browser-based IDE. 

“The focus is really making it easy for people to build enterprise artifacts,” he said. “Very soon, we will add support for Functions, RBAC, and additional data connectors in OneLake and Blob Storage. Then you will have the full suite of tools to build within an enterprise tenant. As we look forward to the end of the year, we want to support more B2B and B2C services. We want to make it easier and easier to get started with Rayfin. We’ll have a perpetual free tier offering. We encourage everybody to go do that.”

Fabric and databases

Microsoft is increasingly re-defining its databases for AI workloads. HorizonDB, available in public preview, is a managed PostgreSQL-compatible database that combines PostgreSQL capabilities with cloud-scale architecture. The offering incorporates elastic storage with the option to scale up to 128 TB and is zone resilient by default. It comes equipped with vector search, integrated AI model management, and direct connectivity to Fabric.