§4. Same‐name declarations

Two declarations with the exact same name and parameter types in the same class are a Kotlin compile error — the type-checker sees both before the IR phase where Platform Weaver runs.

// Kotlin frontend duplicate error, Platform Weaver never even gets to run
@FabricOnly val configDir: String = "config/mod"
@PaperOnly  val configDir: String = "plugins/Mod"

This is intentional and will not be fixed — it's actually a feature.

The pattern around it

If you need the same name on both platforms, that's a signal the concept belongs behind an interface. Define it once in shared code, implement it per platform:

// Shared. No annotation, compiled into every JAR
interface PlatformPaths {
    val configDir: String
}

// Compiled into the Fabric JAR only:
@FabricOnly
object FabricPaths : PlatformPaths {
    override val configDir = "config/mod"
}

// Compiled into the Paper JAR only:
@PaperOnly
object PaperPaths : PlatformPaths {
    override val configDir = "plugins/Mod"
}

Shared code talks to PlatformPaths. Each JAR ships exactly one implementation.

This same adapter idea is how you handle structural divergence with @Chameleon: normalize the differing platform data behind one small type, then let the shared code — and your chameleons — speak only to that.