Reactor — Wrapping Arbitrary Controls (source generator)

Use this skill when the app needs a control Reactor has no built-in factory for — a Windows Community Toolkit control, a third-party vendor control, or the app's own custom Control subclass. The Reactor.Wrappers.Generator source generator turns the control into a first-class declarative element (init-props + ControlDescriptor + Pattern-A registration + a parameterized factory named after the control) from a single annotated partial record. No hand-written wrapper, handler, or registration code.

Canonical worked example: samples/apps/wct-controls/ (declarations in WctControls.cs, usage in Program.cs). Design spec: docs/specs/058-control-wrapper-generator.md. For controls the generator still can't express, drop to the hand-written ControlDescriptor / IElementHandler path in docs/guide/extending-reactor-controls.md.

The whole feature in one example

using Microsoft.UI.Reactor.Wrappers;   // the [Wrap*] authoring attributes