public static class DesktopHotReloadTurns on every reload channel for every application in this process.
No guide page documents this yet — the page shows what the code says about itself.
Remarks
Referencing this assembly is the whole of the opt-in. There is no call to make and no options to set: a module initializer fills the two hooks UiDevelopment leaves open, and every UiApplication constructed afterwards mounts its content under a reload host and gets a stylesheet watcher over its own source directory.
⚠ An application that wants none of this does not reference it. The reference is conditioned on Debug in the sample and in the vixen-app template, so a Release build does not resolve the assembly, the initializer never runs, and the hooks stay null — which is the ordinary build. There is no runtime flag to get wrong and no #if in anybody's Main.
⚠ An application that wants something else still wins. UiApplicationOptions.Mount is checked before Mount, so an application with its own idea of how to mount keeps it.