To just the author and mods, unfortunately we cannot support this yet, as we don't have a "post author" pseudo-group. That is a good idea, though.
We did accomplish this via nodebb-plugin-support-forum, you could try this and see if it still works?
It catched my eye how similar it its to the nodebb default composer.
Would a web versión of this fit the nodebb needs?
I think it would be great to be able to not worry about this aspect on nodebb and simply attatch markdown as a dependecy like this.
Looks like a standalone app as opposed to a web library, unless I misread.
In any case, we don't typically offer compatibility with X markdown editor or whatnot for a variety of reasons:
The short of it is, it takes quite a bit of work to ensure compatibility and full functionality, which is why at current we only support default and redactor.