Currently two modules have implementation dependencies on api.progress:
core.execution - uses module.Controller and spi.InternalHandle from Install
progress.ui - uses various spi.* and module.ProgressListAction from various classes
We are trying to remove impl deps from the platform cluster and these seem pretty easily solvable. Would need to move Controller and ProgressListAction into the spi package, review what this package exports for basic API design principles, and make it public.
Implemented in prototypes #bb9ae35d671c, though SPI package probably needs cleanup and documentation before finalized.
Fix is in trunk, see master issue.