@laurent Thanks, as far as I can tell, the external editing support in Joplin is not what I’m talking about.
If you are familiar with a GIT/Github workflow, each repository/folder has a top level MD file which is versioned along with the repository. Each time I checkout the repo or commit new changes, the MD file is versioned with it. The MD file may also be edited online using a Github editor in the browser, and commited/versioned there, so next time I checkout the repo, the updated MD file is replaced on my local file system. It may be edited on my local file system by my develoment tool, e.g. IntelliJ. Any of those external changes need to be automatically synchronised with what Joplin sees. If I have to re-import the externally modified MD into Joplin to see changes, then this defeats the purpose as Joplin is seeing an old version of the MD. Further, if I were to modify the MD in Joplin, I would then have to remember to re-export it in MD format back into my repo’s folder (replacing the original) so that then I commit and version those changes. This is inconvenient and error prone.
I realise Joplin stores the content in a database, to satisfy my usecase, off the top of my head, I imagine Joplin would need an option while importing an external MD file, which specifies that I want to track this external file, then Joplin records the path in its database and knows to watch for changes and automatically update its copy of the file. Also any time I make changes using Joplin, these are exported automatically to the original location. I guess to make this feature complete, one would also need a way to update the path to the external file in Joplin for times when you move folders around on your file system.