[pkage]

For me, that's manual—I make sure everything I've cited is in the .bib file, and move papers into another collection if they end up not being relevant for a particular paper.

This is probably an automatable task, but it's generally not too much of a burden to do manually. I add a 'needs-review' tag to papers I've identified in a literature review, and categorize it when I get around to reading it.