After the Scala 3.2 release added ‘Code Completion for Refined Types’ (Scala 3.2.0 released! | The Scala Programming Language ), the auto-complete now works great in Metals
Unfortunately it does not work in IDEA yet.
I created an IDEA issue here https://youtrack.jetbrains.com/issue/SCL-20993/No-auto-complete-for-Scala-3-transparent-inline-method.
However, this macro is pretty complicated. And the the use case is very common in any data modeling domain.
@markehammons explains with more detail in Allow structural types to be completely generated from match types
If we could use match types & inline to define our own structural types, I bet 90% of macros in the wild could be eliminated.