I'm building a note-taking app, so I hope you don't mind, but I was wondering if you might describe how you "search" your notes while using a device's file system search? For desktop, I might use a tool like grep to do that, but that's pretty developer-y, so if you're doing something more user-friendly, that's interesting to me. What is more interesting to me, though, is what you're using on mobile to do this? I've never, personally, used my mobile's file system search to discover text in notes. But I'm on Android, so there's not really only one 'file system' with a search interface.
My thought here is it that the app is going to be saving simple text files either plaintext or richtext (markdown/html), so it should be able to provide this for you, but I haven't even considered that as a feature so I would want to test it to see if there were any rough edges to polish. Any suggestions you have would be appreciated!