Mlem shows it like Lemmy. No screenshot necessary.
Summary: In Markdown, you need to add 2 or more spaces at the end of a line to force a line break. I didn't do that. A client app and a Lemmy instance show the text correct without a line break. PieFed adds a line break.
I have written a big chunk of the markdown_to_html function at this point, I can try to take a look at this. A situation like this isn't anything we have added to the function, so it must be how the markdown2 python library we are using is interpreting things. Ideally, this is the behavior I would want for line breaks.
Yes, markdown_to_html() in app/utils.py sets the breaks of markdown2 to on_newline.
From the documentation (in the source file): on_newline: Replace single new line characters with br> when True
(WOW! I missed escaping the br> and it made a line break in the preview?)
Yep, I just made a PR. I am so used to the more normal way markdown works that I never actually ran into this issue before. I am not sure if this change might break something else in the codebase since markdown_to_html is used in lots of places, so I will let @rimu@piefed.social review it instead of just merging it myself.
Yes, it gets used for emails, too. Server admins would need to change their email texts. That's bad. But at this time the number of instances with PieFed is still below 1,000.