Currently it just registers undo and rollback edits. I have provided a checkbox to people to mark the edit as spam.
Repo is at mediawiki/extensions/BayesianFilter
You can clone with
git clone ssh://gerrit.wikimedia.org:29418/mediawiki/extensions/BayesianFilter
git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/BayesianFilter
I wanted to collect some data so that it I can start analysis on them