RESTBase already stores information about the namespace of a page. The next step is to provide this listing to the public via the following API endpoints:

• /{domain}/v1/page/namespace/: lists all of the available namespaces, including aliases (if any), and perhaps canonical names as well
• /{domain}/v1/page/namespace/{namespace}: gets info about a namespace, such as ID, name, aliases, canonical names, etc.
• /{domain}/v1/page/namespace/{namespace}/: lists all of the pages available in storage that belong to the namespace with the given name; note that {namespace} may refer to a namespace's ID, name or alias

This should be easily-achievable. Specifically, it warrants the creation of a second table, which would store information about namespaces. Then, linking it to the table of pages titles (via the namespace property and the by_ns secondary index) should give us the list of pages in the given namespace.