fun main(args: Array<String>) = runBlocking {
  println("Program start")
  val jobLoop = LazyJobLoop(Dispatchers.Default)
  jobLoop.job.collect {
    withContext(it) {
      println("In withContext")
    }
  }
  Unit
}

interface JobLoop : CoroutineScope {
  val job: StateFlow<Job>
}

class LazyJobLoop(
  coroutineContext: CoroutineContext,
) : JobLoop, CoroutineScope by CoroutineScope(coroutineContext) {
  private val _job = MutableStateFlow(launchJob())
  override val job = _job.asStateFlow()

  private fun launchJob() = launch(start = CoroutineStart.LAZY) {
    println("In job")
  }
}

Exception in thread "main" java.lang.IllegalStateException: Job is still new or active: LazyStandaloneCoroutine{New}@544a2ea6

CoroutineContext

jobLoop.job.value.start()

jobLoop.job
  .onEach { job ->
    // Maybe do some suspending work beforehand,
    // like fetch another resource, get a fresh token, whatever
    job.start()
  }
  .launchIn(myClientScope)

launch { }

start