Using custom dependency rules for scalafix-migrations with 'type: "build"'

[cptwunderlich]

I tried using a scalafix-migration with type: "build", which uses a custom rule, published to a private repository.
But I realized, that these types of migrations are run with scalafix CLI, which does not resolve rules from other repositories. One would have to explicitly call it with scalafix --tool-classpath $(cs fetch myorg::rules:vesion -p) --rules=MyRule.

Is there any reasonable way to add this functionality to scala-steward?

My use-case is this: We have an internal meta-package and we are preparing an upcoming release with many changes, e.g., upgrade to Play 2.9.
However, Tapir jumped straight to Play 3 for its submodules (e.g., tapir-play-server) and I created a new submodule for Play 2.9 instead (tapir-play29-server). So I need to rewrite the Dependencies.scala file.

I also looked at the artifact migrations, but it seems like this only works if the listed artifact itself has a new version.
Post-update hooks seem a bit hacky for this scenario and there is no way to apply this to a specific version only.

[fthomas]

One would have to explicitly call it with scalafix --tool-classpath $(cs fetch myorg::rules:vesion -p) --rules=MyRule.

Is there any reasonable way to add this functionality to scala-steward?

One way to support this is to add a toolClasspathCmd: Option[Nel[String]] field to ScalafixMigration which is a command that is executed before the migration and whose output is used as --tool-classpath argument to the subsequent scalafix call.