Tool builders have asked for information about the federation scenario of a Wikibase instance to be included in WikibaseManifest. Currently there are two such scenarios, both of which can and should be expressed via the concept of entity sources:

• the MediaInfo extension as used on Wikimedia Commons, with wikidata.org as the entity source for Items, Properties and Lexemes
• the Federated Properties feature with the federation source repo as entity source for Properties

The Federated Properties documentation shows an example of an entity source configuration on a Federated Properties enabled Wikibase. WikibaseManifest could also include RDF prefixes. The entities section in the prototype examples may be a good place to include entity source information, and should be renamed to entity_sources.

(see T261195 and commments for underlying investigation)