I am trying to imagine what this implies, but my gut feeling is that it would work with #3 as well. Calva Formatter (or if it is VS Code) isn’t ready for full out formatting-as-you-type, so today it happens mainly when new lines are typed. And I think that it would be convenient to have the formatter tidy up the code with newlines improving the formatting. It is when the new lines are removed that it starts risking to be a fight between the coder and the formatter. I see my colleagues put a few lines around the code being typed while they think and experiment, and then when they are done they fold up the paren trail and delete extraneous newlines.
A requirement that I might not yet have expressed is that I would like to have empty lines around the cursor indented such that entering something at the end of them would have that something correctly indented. I ”fool” cljfmt to help me with this today, by inserting a symbol in the text where the cursor is before formatting and then remove that symbol when replacing the text in the editor with the formatted version. Speaking of this, I recently had an issue fixed where cljfmt trimmed trailing space on empty lines (despite :trim-trainling-whitespace being set to false). So that is also important. (I think I posted a link to that issue above with a GIF showing why it is important.)