Context

The API of langgraph.store.BaseStore basically looks like a file system where namespaces are directories, keys are files, and values are the contents of the files. list_namespaces provides a way to explore your memory store with find-like behavior. This is great, but it only provides directories (namespaces), not the files (keys) within them. For simple stores, one often might have just one level, like "users". One would like to get a list of all the users, not just know the name of the directory.

Definition of done

One has to decide the API. list_keys isn't defined on the BaseStore and list_namespaces doesn't have kwargs so one option would be to simply add a function list_keys. It would reuses much of the complex MQ, though. The other option is to extend list_namespaces but then we break from the API of the base class, and provide more than just namespaces as the name suggests.

Pitfalls

None. Usage of these stores is typically via user-defined nodes, so we are not constrained.