How to serialize materialization of `concat`enated sources?

Akka Libraries Akka Streams & Alpakka
1

So I have a Source of Committable[A] elements

case class Committable[A](commit: () => Future[Unit], value: A)
val source: Source[Committable[A], NotUsed] = ...

and I want to transform it into Source that runs commit after successful processing of value by downstream.

The naive implementation (that works with fs2 btw) is:

def autocommit[A](in: Source[Committable[A], NotUsed]): Source[A, NotUsed]  =
  in.flatMapConcat { c =>
    val commit = Source.single(())
      .mapAsync(_ => c.commit())
      .flatMapConcat(_ => Source.empty[A])
    Source.single(c.value).concat(commit)
  }

The problem is that c.commit() is called regardless of how c.value is processed by downstream. So the following code would commit:

autocommit(source).mapAsync(1)(_ => Future.failed(new RuntimeException))

As I understand from docs this is kinda expected behaviour due to materialization and buffering.

So is it possible to achieve what I want?