Late last night I added delete/update markdown. Even though the implementation is a little greedy, it felt great to finish it in much less time than I was expecting.
Today, I made some more improvements to nested marks (i.e. bold inside italic) and added support for links: markdown-syntax, autolinking, and email detection.
Part of my brain is nervously waiting for something to spring up that halts progress. There are already some small bugs, but nothing show stopping. I can fix them later.