§2. Annotations

Platform Weaver decides what stays and what is stripped from each build based on platform annotations.

Built-in annotations

Annotation	Kept when building for	Stripped when building for
@FabricOnly	fabric	Paper, Neoforge, anything else
@PaperOnly	paper	Fabric, Neoforge, anything else
@NeoForgeOnly	neoforge	Fabric, Paper, anything else

A declaration with no platform annotation is compiled into every JAR. A declaration annotated for a platform other than the target is removed before bytecode is written, so its platform-specific types never need to resolve at runtime.

Custom platform annotations

Platform Weaver isn't limited to the three built-in annotations. Define your own in one line with @PlatformOnly:

import io.github.arnodoelinger.platformweaver.PlatformOnly

@PlatformOnly("spigot")
@Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY)
@Retention(AnnotationRetention.SOURCE)
annotation class SpigotOnly

The string passed to @PlatformOnly is the platform key matched against your build's target. The plugin picks the annotation up automatically — you don't need to add it to the compiler plugin classpath.