There are endpoints for adding and removing podcast episodes to a user’s library (Web API Podcast V1.0 | Amazon Music Web API), but there’s no way to check the user’s library to see if an episode is present. This step is essential for verifying whether a user already has an episode in their library or not. There are similar endpoints for checking other types of resources in a user’s library (podcast shows, albums, artists, etc), so it would be helpful for consistency to have this ability for podcast episodes as well.