On a software product note, "Pocket", the client-side product that does local-only interest analysis so it can get a full list of interesting articles from the server, and then locally filter out all the stuff you probably don't care about, is not "the server application that accepts volutary user submission analysis to determine what goes on the API response list with which categories".

No one ever talked about open sourcing the service that the pocket client relies on, as far as I can remember.