I really like this idea. I currently use https://hackmd.io/ sometimes. I like that files can be stored and reloaded there. I use pastebin sometimes, it's very handy for a variety of code. Although I wish I could have private links. Maybe I haven't quite figured it out yet.

Frontend: have you seen https://www.parley.io They do something to only show content from their tag I think. Doesn't go both ways though.