In addition, I would love a clickable link to search for the message online, as I mentioned before on Compiler warnings/errors with http document pointers to help resolve them
I’m not sure this is a good idea. I’m afraid of having external links that can die in an error. I would be even wary of linking to the Scala docs website from it I think having an error catalog and forcing you to search for the id is a better solution with a lower maintenance cost and lesser risk.
Absolutely 
I’d like the new architecture to allow users to filter warnings.
Any concrete suggestions? I believe this is an area where we can innovate compared to other languages: implicits need special suggestions and tooling support to be nicer to use.