The document ID (partial name) of CiStaging is:

static String documentIdFor({
  required RepositorySlug slug,
  required String sha,
  required CiStage stage,
}) => '${slug.owner}_${slug.name}_${sha}_$stage';

However, none of those fields are stored in the document itself.

Not only does that mean it's hard to query, but it breaks the AppDocument model where it is supposed to be possible to, given a T (including one yet to be inserted into Firestore), determine it's ID.

We can work around this by adding getters/setters, but it's not ideal.