Ok it's domain/port level - the problem is the same. Do you even get the problem?

[flagged]

No. That is for the host/domain entirely not a specific stream.

I might want several directories in the future, and even if I don't, I might want it separate from my .well-known robots.txt. Many, many reasons I can think of not to blend these.

Bad idea.

I don’t love well-known for this because it isn’t app- or account-level it’s host-level.

And maybe I want 2 of those directories.

SSL, file-based verifications, sure. Not for this.