Summary

Microsoft UI Reactor is an experimental C# framework for building WinUI 3 desktop apps declaratively. It brings patterns like co-located state and type-safe UI composition, familiar to React/SwiftUI developers, to WinUI. Reactor enables full C# IntelliSense and refactoring while seamlessly interop-ing with existing WinUI XAML/MVVM codebases, offering a modern development experience.

How It Works

Reactor uses a virtual element tree and reconciler to efficiently update WinUI controls. Its C# DSL replaces XAML with typed factory methods and fluent modifiers. State management is co-located with render logic via hooks (UseState, UseEffect), eliminating ViewModel boilerplate and leveraging C#'s compile-time safety for UI development.

Quick Start & Requirements

• Installation: Build from source via bootstrap.ps1 (approx. 3 mins). Clone repo, run .\bootstrap.ps1, then dotnet new reactorapp, cd MyApp, dotnet run.
• Prerequisites: .NET SDK, PowerShell.
• Links: GitHub Repository

Highlighted Details

• Core Reconciler (Preview): Virtual DOM, element pooling, render coalescing, skip-unchanged optimizations.
• Hooks & State (Preview): UseState, UseReducer, UseEffect, etc., for state management.
• Flex Layout (Preview): C# port of Facebook's Yoga engine.
• Charting (Preview): Declarative DSL for charts based on D3 algorithms.
• Live Preview: Hot-reloading via CLI (--preview) and VS Code extension.

Maintenance & Community

Currently "Experimental" with an expected 3-6 month iteration target. Contributions and feedback are welcome. Hosted on GitHub with all code, specs, and tests public.

Licensing & Compatibility

• License: MIT.
• Compatibility: Seamless interop with WinUI XAML/MVVM apps; content can be hosted bidirectionally.

Limitations & Caveats

Experimental, pre-1.0; public APIs may change. Requires building from source (no NuGet). Feature maturity varies ("Draft"/"Early" areas may evolve significantly).