What is the autoritative place for Phabricator repository mappings?

Created by: leoluk

There seem to be multiple places where I can specify the Phabricator repository mappings:

• Phabricator settings for the native extension.
• phabricatorMappings managed storage setting for the browser extension.
• Phabricator external service config in Sourcegraph itself.

Which of these need to be specified?