I agree that creating an API is probably the smartest way to go about it. The "disadvantage" to that approach is that I have to build and maintain an API.

The app architecture as it exists is also somewhat conducive to being "split" into an open and extensible part and a closed engine. However, I might wish I had just gone to the full effort of building an API, so that I don't have to constantly mentally track what parts of the code can reside in the be public modules.

Having the app run on a server is also possible, but I have no familiarity with doing that.

Thanks for your thoughts.