The problem with "fast", "direct", and maybe "bare" is that they
describe some property we're trying to provide with these. Like
hidden, I think the chance that they will evolve or be applied in some
way for which these terms won't apply is too great.
I disagree in general. Hidden service is still a perfectly accurate term. “Fast” may have this issue if such services change and take advantage of the fact that the server location is known for other purposes (e.g. location-based security improvements).
The problem with "exposed", "peeled", and maybe "bare" is that these
all imply that these are onion services that are diminished in some
way.
I can see this with “exposed” (although it actually has the advantage of making it clear to the operators that the service is *not hidden*). Neither “peeled” nor “bare” seems negative to me.
because if it ends up not having the .onion
domain name or requiring lookup in the HSdir system etc.
This doesn’t seem relevant. We are discussing an existing proposal, in which the .onion domain and Tor's name resolution service are used.
This is another reason why [modifier] onion service is
problematic; it will almost certainly get shortened in use, just
as location-hidden service did.
The obvious and suggested shortening (i.e. omitting the word “onion”) works well, in my opinion.
Here's one suggestion: must-tor service (or mustor service if we want
to be even more compressed.
This reminds me of the “Tor-required service” suggestion you initially made. I dislike like it for the same reasons, the primary one of which is that it uses two entirely separate names for services that actually will probably indistinguishable to the user. That’s why I like the “onion services” umbrella over both hidden and fast/direct/exposed/public/peeled/etc.