FfmLibrary

One host library reached with java.lang.foreign, and the symbols bound out of it.

Every JVM binding koblas ships opens its library the same way: try each candidate name in turn, keep the first that both loads and carries a key symbol, and bind handles out of it lazily. This is that, so a binding contributes only its prototypes. The native targets have openNativeLibrary for the same reason.

Handles are bound with Linker.Option.critical by default, which lets a call read and write the Kotlin arrays handed to it in place rather than copying them.

Calls on the result use invokeExact, a signature-polymorphic call site: the descriptor lands in the bytecode, where invokeWithArguments would box every argument into a varargs array and pay a fixed cost per call that a short routine cannot amortise.

The exactness is load-bearing. invokeExact converts nothing, so an argument whose Kotlin type does not match its layout throws WrongMethodTypeException where invokeWithArguments would have widened it silently. Two consequences for the call sites: a routine called for effect whose descriptor returns a value still needs the cast, since Kotlin infers Unit in statement position and emits a void descriptor that will not match; and a safe-call chain has to be resolved to a local first, because as Unit? is the boxed Unit rather than void.