RESTbase is exposing a REST API for listing related pages under the v1/page/related/ path. This endpoint is backed by a call to the action API, namely action=query&generator=search&gsrsearch=morelike:. To unblock the subsetting of RESTbase, this functionality whould be replaced with a REST API implemented in PHP, which uses the same PHP code that also handles the action API query.

The handler in RESTbase enriches the response with page summaries. This would have to be implemented in the client, or the PHP code would have to call out to the summary endpoint.

Requirements and usage of this API need to be clarified. It seems likely that it was created for use by the RelatedArticles extension, but further reasearch is needed.

Note that the endpoint is marked as "experimental", so we are not stricly required to keep the public URLs intact.