sorry, i had just updated my post at the same time as you posted to clarify mastodon’s implementation vs my general position on the spec!
Gotcha! Thanks. I should have double checked before logging off last night & saved you the trouble.
I don’t mean to continue the derail. If I can summarize, it sounds like the conclusion is that “using JSON-LD framing may cause some federation problems right now (for various software), but is a tractable problem with a solution that could be provided for the future”. Feel free to correct me.
I ran into this object id #fragment problem as well. It seems because of some URL normalization, Mastodon will remove the fragment, and drop any additional posts with different fragments (because they become the same url).