wikimedia/mediawiki-services-eventstreams — reverse-engineered prompt

Build me a JavaScript service for MediaWiki event streams. I want people to be able to connect from a browser or command line client and subscribe to live wiki events using Server Sent Events, with the events coming from Kafka in the background.

Please make it feel like a real production service, with a main server, routes for requesting streams, configuration files for local and production use, and a clear API spec so other teams can understand how to use it. Include a simple web UI where someone can pick or type a stream name and watch events appear live. Add basic error handling for bad stream names, disconnected clients, and Kafka connection problems.

Also include tests for the important behavior and a short README that explains how to run it locally, how to configure streams, and how to try it with a sample curl command. The old README says the repo moved to Wikimedia GitLab, so look up the current docs online if you need to.