Kotlin

Writes, debugs, and reviews Kotlin: coroutines and flows, null safety, collections, Java interop, and Compose state. Use when an NPE hits a non-null type, `!!` or a Java platform type blows up, a coroutine leaks, never cancels, or swallows exceptions, a StateFlow stops emitting or a SharedFlow drops events, a Compose screen recomposes too much or loses state on rotation, `equals`/`copy`/`==` behave unexpectedly, a `when` stops being exhaustive, kapt/KSP or JVM-target errors break the Gradle build, JSON puts null into a non-null property, a coroutine test hangs or passes only in isolation; also