The initial version should have:

• Special:ActivityMonitor:
  • List changes to the local wiki (near) real-time.
  • Ability to view the "diff" of an edit.
  • Access to various filters to control the flood (e.g. most commonly users will want to reduce the list to changes not yet patrolled, and perhaps only show edits vs. page creations, namespace filter etc.).

• Database API
  • Store and retrieve page names and user names that warrant special attention of sorts. Both viewing and modification of this needs to be restricted by user rights (a bit like abusefilter-view and -modify, and patrolmarks/patrol/autopatrol).

I'm leaving out lots of nice-to-haves and even features required for the minimum viable product deployment, but this is just a verbose summary describing what the two modules of ActivityMonitor that the MVP would have look like, not so much its features.