I really like how SharePoint and Teams let you save opened documents or spreadsheets back directly from the app. I expected some proprietary protocol and was really surprised to learn they actually use WebDAV.
It tooke me a few hours of tweaking responses to various DAV HTTP methods, like LOCK, UNLOCK and PROPFIND, but I ultimately created a very simple PHP script that wasn't perfect, but worked with just minimal annoyences (like various prompts, some of which are present even on SharePoint).
I've always wanted to do a proper file manager, like Total Commander, so this was a great excuse to create one. I started developing scripts to show various file types and I was REALLY happy about that, especially because some of them were actually more useful, than my current work setup, and I ended up using it not just for fun, but for regular work as well.
I didn't have to hold myself back, because the main deploy target is Qik Home Server and not a public webhosting, therefore I (for once) can use things like `exec`.
For metadata I chose SQLite and I finally decided on a database model. When I was going to implement it, I had to laugh, because I found pretty much the same exact model I created way back in 2018.