Internals: Why does compose not use java.lang.ThreadLocal on JVM, but a custom ThreadLocal implementation?

Compose does use java.lang.ThreadLocal on JVM, just through a wrapper. You can't directly use a JVM-specific class in multiplatform common code.

Ok, it does define an external/actual for ThreadLocal, although I have not found any usage of it. The question should be why a

SnapshotThreadLocal

is there`.` But as I see now it is already documented - it has lower overhead than JVM/ART implementation.