Even is sometime is core now, keep it as a seperate boundry anyway.
one option is to have a discovery context which have search catalog and recommendations. But if you know that one of those things is going to be a key part of the business in the future and you want to improve one of those things prematturly optimize so you can iterate on this bounded context faster.
Use these at a strategic level when defining bounded context. When you want to seperate core domains from supporting and generic subdomains