This task involves the work of introducing an Edit Check that offers people feedback when the link they are attempting to add matches an entry on`MediaWiki:BlockedExternalDomains.json` which T337431 introduced.

Introducing this check would be an extension of the underlying technically capabilities, and potentially design patterns, T349261 and T347531 will introduce.

Stories

• As someone attempting to add a link to a domain that a project has deemed to be vandalistic/spam, I want to be made explicitly aware of this as soon after doing so as possible, so that** I do not waste time investing in an edit that I'll ultimately be prevented from publishing.