What is Rayfin Fabricator?

Rayfin Fabricator is a desktop workbench (Windows 10/11 and macOS Apple Silicon) for building Rayfin apps. It combines chat-to-build, a Monaco code editor, a live inline preview, and one-click deployment to Microsoft Fabric in a single window — so you never have to juggle CLIs, terminal tabs, and a browser. It's built with Tauri v2 (Rust core + React renderer) and runs on your existing GitHub Copilot account. Important: it's a personal project by Sachin Patney, who works at Microsoft, but it is NOT a Microsoft product and is not affiliated with, endorsed, or supported by Microsoft.

Rayfin is Microsoft's Backend-as-a-Service for the agentic era (github.com/microsoft/rayfin). You define your data model with TypeScript decorators, and the platform provisions and manages the database, authentication, data APIs, storage, and hosting for you — all on Microsoft Fabric with enterprise-grade governance. Fabricator is the desktop shell that makes building those Rayfin apps effortless.

Do I need a new subscription or account to use Fabricator?

No. Fabricator runs on the GitHub Copilot account you already have — nothing new to sign up for and no extra subscription. Copilot ships bundled with the app, so you don't need a separate global Copilot install or terminal login. You sign in to GitHub Copilot and Azure through the app's onboarding, and sign in to Microsoft Fabric when you open a project and deploy.

How do I install Rayfin Fabricator?

Download the latest release from GitHub. On Windows, grab the x64-setup.exe — it's Authenticode code-signed via Azure Artifact Signing (SmartScreen reputation builds over time, so early downloads may warn; choose More info → Run anyway). On macOS Apple Silicon, grab the aarch64.dmg, drag to Applications, then clear the quarantine flag once with: xattr -dr com.apple.quarantine "/Applications/Rayfin Fabricator.app" — the macOS build is ad-hoc signed but not yet notarized, so this one-time step prevents a false 'damaged' warning.

What does the build-and-ship loop actually look like?

You describe what you want in plain English; the bundled Copilot agent writes and edits project files while git snapshots every change for diff/rollback. You inspect and edit any file in Monaco, view your data model as an entity diagram, and watch the app in a native inline preview. Hit deploy and Fabricator runs 'rayfin up' to ship to Microsoft Fabric, managing create/switch/redeploy across workspaces and sharing with tenant teammates from one panel. An AI Advisor runs security and policy checks — flagging unprotected routes or over-permissive database policies — and offers one-click 'harden' prompts.

Rayfin Fabricator: A Chat-to-Ship Desktop Workbench for Building Microsoft Fabric Apps

By Prahlad Menon Published 2026-09-17 4 min read

If you’ve ever built a backend app the modern way, you know the tab-juggle: scaffold with one CLI, prompt an AI agent in another terminal, run a deploy command, flip to a browser to check it, wrangle git, repeat. Rayfin Fabricator collapses that entire loop into a single desktop window. You chat, the app gets built in front of you, and you ship it — no commands to memorize, no terminal tabs to babysit.

First, the honest disclaimer the author leads with: Fabricator is a personal project by Sachin Patney, built in his own free time. He works at Microsoft, but this is not a Microsoft product and is not affiliated with, endorsed by, or supported by Microsoft. Worth stating up front because the tech it targets — Rayfin and Microsoft Fabric — is very much Microsoft’s.

What’s Rayfin, and why a workbench?

Rayfin is Microsoft’s Backend-as-a-Service “for the agentic era.” You define your data model with TypeScript decorators, and the platform provisions and manages the database, auth, data APIs, storage, and hosting for you — all running on Microsoft Fabric with enterprise-grade governance baked in.

That’s a powerful backend, but building against it still means living in the CLI. Fabricator is the desktop shell that wraps those tools so you don’t have to run them by hand.

The four-part loop

Fabricator organizes the work into a tight cycle:

Chat to build. Describe what you want in plain English. A bundled GitHub Copilot agent writes and edits your project files — you never touch a command line. Git quietly snapshots every change, so you can diff and roll back anytime. You pick the model and reasoning effort, steer mid-turn, and keep separate threads with full history.
See it as it’s built. Inspect and edit any file in a built-in Monaco editor, view your data model as an entity diagram, and watch the running app in a native inline preview — with navigation, reload, devtools, a Fabric portal shell toggle, and annotate-a-screenshot-straight-into-chat. No separate browser, no copy-pasting URLs.
Deploy with a click. Hit deploy and Fabricator runs rayfin up for you, shipping to Microsoft Fabric. A deployments panel handles create, switch, and redeploy across workspaces — then shares a deployed app with people in your Entra tenant by email (each recipient gets Contributor on the workspace).
Harden it. An Advisor runs Copilot-driven security and policy checks — unprotected routes, over-permissive database policies — and flags them when the project changes. The Model tab flags loose access on any entity and hands a one-click “harden” prompt straight to the agent.

No new subscription — that’s the clever part

The best design decision here is authentication. Fabricator runs on the GitHub Copilot account you already have. Copilot ships bundled with the app, so there’s no separate global install and no terminal login — setup verifies auth and model access through the same engine that powers chat. It even handles the annoying edge cases gracefully: expired Copilot credentials can be refreshed mid-conversation without clearing your draft, GitHub Enterprise Cloud data-residency hosts are supported, and Azure/Fabric sessions are checked separately rather than silently failing.

Under the hood

Architecturally, it’s a clean Tauri v2 app: a React 18 + TypeScript renderer drives the workbench UI (chat, editor, model view, preview, deployments, advisor, skills, history), and a Rust core owns the IPC handlers and services for running external tools, persistence, preview hosting, telemetry, auto-updates, and crash logging. It shells out to the GitHub Copilot CLI to author and the Rayfin CLI to deploy, tracks the project with git, and loads the deployed app into an embedded WebView preview.

Getting it running

Fabricator supports Windows 10/11 and macOS (Apple Silicon), downloadable from the releases page. The Windows installer is Authenticode code-signed via Azure Artifact Signing (SmartScreen reputation still builds over time — early downloads may need “More info → Run anyway”). The macOS build is ad-hoc signed but not yet notarized, so you clear the quarantine flag once:

xattr -dr com.apple.quarantine "/Applications/Rayfin Fabricator.app"

That one-time step avoids a false “damaged and can’t be opened” warning; it goes away once the app is notarized. The app auto-updates on both platforms.

The takeaway

Fabricator is a smart example of a pattern worth watching: instead of asking developers to learn yet another agentic CLI dance, wrap the CLIs you’d already run into one opinionated desktop app and let the AI agent, git history, live preview, and deploy button share a single surface. For teams building on Microsoft Fabric with Rayfin — and who already have Copilot — it removes almost all the friction between “describe an app” and “share it with your tenant.”

Repo: github.com/spatney/rayfin-fabricator