What would you think of just adding a boolean value to each podcast called favorited or something? That would prevent issues with non-existent IDs.

That's a better idea. It also prevents the breaking up of information about an individual podcast into multiple sections. It keeps all the data about the show in one place. Much better.

Do you have any preferences about module structure? Is there a published pattern you're following that I can conform to if I take a pass at this?

Honestly, it's not too rigid. I'm trying to follow the cobra guidelines for the different commands. I'd also still like to have the program available as a library and the cli is just an interface on it. Other than that, just the general go stuff (gofmt), introduce as little dependencies as possible, ... Nothing too crazy :)

In any case: thanks for helping and enjoy ;)

Thanks for starting the project! Let me know if I hit out of scope features. You've done great stuff here and I think it could easily become a really powerful library, but I want to be respectful of your goals. I'm already tinkering with integrating it into my own podcast flow. ;)