The Title objects returned by EntityTitleLookup for foreign EntityIds should produce a title that refers to the respective target wiki. In order to achieve this, two things must be known:
- the interwiki prefix for the target repo. This should, by convention, be the same as the repo name. But we'll need a mechanism to enforce this, or to provide a mapping in case this assumption doesn't hold.
- the page title on the target wiki. This means we need to either know the namespace name for each entity type on the target wiki, or we need a way to link without knowing the namespace name. This could be achieved by each repo exposing Special:EntityPage, which will redirect to the correct local page given an entity ID.