Lemmy's spoiler format is

As described here

The regex I've come up with is :{3} spoiler\s+?(\S.+?\n)(.+?)\n:{3}

It won't do spoilers inside spoilers, but that's a pretty niche case.

The changed code is viewable on GitHub

Any thoughts or suggestions for the regex before I create the PR?

I'm assuming that if I create a PR, and if they accept it, they'll (eventually) release a version with it in, and the line in pyfedi's requirements.txt can get version bumped. This seems like the 'proper' way to do it, but it's a bit long-winded, so maybe there's a better way to do it.