Extension()
Browser availability: desktop-only.
This API requires the desktop runtime. Browser declarations may report the limitation without performing the operation.
An extension: found through ServiceLoader (a line in
META-INF/services/org.openpatch.scratch.extension.Extension) or registered with
Window.use(...), installed once when the window is created. Learner code never sees
it.
The metadata lives in code, not in a resource file, because the fat jar shades every first-party extension into one jar, where a fixed resource path would survive only once.