• In SCM, we have input modulemd yaml, prepared by users.
• When that gets submitted to MBS, we modify it to set stream name, version, etc. We resolve stream names to refs in some place as well.
• We want to publish that modified modulemd yaml to fedmsg when we advertise the wait state so that pdc-updater can pick it up and store it in PDC.

Compose tooling later will pull that modified yaml from PDC in order to bake it into the composed repo.