Just another update. I've had to pause a week here and there to work on other plugins, but CB Activity is still progressing. Relational tables for mentions, tags, hashtags, and liked activity are now implemented. These tables are hyper optimized to contain simple pointers. What this means is it's possible to filter a stream down to all posts you were mentioned in, all posts you were tagged in, all posts with a specific hashtag, and all posts you've explicitly liked. This is all done blazing fast against a table with MILLIONS of rows so rest assured it will scale.
In addition to this the mentioned behavior shown above is finalized. Hashtags also now has an autocomplete just like mentions. The contenteditable behavior of the activity post has also been finalized. Other sites and solutions use bulky WYSIWYG editors loading tons and tons of JS, but CB Activity is using a scratch made solution that's light and blazing fast!
The filtering behavior for activity streams has also been finalized. You can setup as many filters as you need, set access for them, and restrict them to stream owner. Filters can filter by asset, by stream id, and by user ids. They can be named whatever you like and you control the default filter (the All filter) for streams.
Still a lot more to do, but our ticket tracker below is looking more and more done!
forge.joomlapolis.com/projects/cb-activity/issues