When the file changes, we could be adding a reference to MongoDB (a new empty file that we just started working on) or removing references to MongoDB (for example, refactoring code). We will show or hide the toolbar whenever the file contents change.

Tech Design: https://docs.google.com/document/d/1zcKexjsb2u5qt7e08pZxF1g339WF8vHiF6zCjRj0880/edit#heading=h.70onu7jza9dp