This likely falls under T335067: Epic: Wikidata Query Service stabilization

Thanks for raising this. I had totally forgotten about that.
Do we know how many tools, etc assume that there is only one value there? How much and what are we going to break?
I'd love to get some more input from people here.

Also can someone clarify what the connection between the siteinfo API information and Wikibase Manifest is here?

I don’t know where Wikibase Manifest gets its info from, but the response in the siteinfo comes from $wgWBRepoSettings['sparqlEndpoint'] FWIW.

See also T369079 and T374021 where we made WikibaseQualityConstraints use both SPARQL endpoints (via an additional config variable, so that the existing one still only contained a single string).

In T394456#10829446, @Lydia_Pintscher wrote:

Do we know how many tools, etc assume that there is only one value there? How much and what are we going to break?

• All Pywikibot users: https://gerrit.wikimedia.org/g/pywikibot/core/+/b7f493b4820c42d2f514d1bc4cee3c4d7eb5ca54/pywikibot/site/_datasite.py#147.
• GitHub search: https://github.com/search?q=wikibase-sparql+NOT+path%3A%2F%5Epywikibot%5C%2F%2F+NOT+path%3A%2F%5Erepo%5C%2F%2F+NOT+path%3A%2F%5Etests%5C%2F%2F&type=code. Some Magnus' tools for example.
• Wikimedia search luckily finds nothing: https://global-search.toolforge.org/?q=wikibase-sparql&regex=1&namespaces=2%2C8&title=.%2B%5C.js

Discovery-Search will be watching, but expecting WMDE to drive the change.

In T394456#10829450, @Lydia_Pintscher wrote:

Also can someone clarify what the connection between the siteinfo API information and Wikibase Manifest is here?

In T394456#10829559, @Lucas_Werkmeister_WMDE wrote:

I don’t know where Wikibase Manifest gets its info from, but the response in the siteinfo comes from $wgWBRepoSettings['sparqlEndpoint'] FWIW.

Looks like WikibaseManifest gets it from $wgWBRepoSettings['sparqlEndpoint'] as well: ConfigExternalServicesFactory.php#9
But it can also be manually specified / overridden with $wgWbManifestExternalServiceMapping: Extension:WikibaseManifest#External_services