CallerAttribution

Names the app on the other end of a binder transaction.

Every guarded verb reads the caller here, on the binder thread, before it hands the work to a coroutine: Binder.getCallingUid() is only meaningful while the transaction is in flight. A UID resolves to a package once and is remembered, because the same app calls thousands of times. install has to run before the first transaction; HostService does it in onCreate.