Somewhat related to JENKINS-55538, when I look at what is currently building, I sometimes want to filter the output (e.g. only see what matches a pattern for nodes or job names). One particular use-case is that we sometimes restart some workers to deploy them from scratch, and before that we want to make sure they are not used by any build that would get aborted.
One simple solution I thought of was adding an optional support to filter the prepared message line (to be posted into IM) with a user-provided regex. In line with solution to JENKINS-55538, such pattern hits can also be accounted and reported in the first line of response.