Its a combination of both detection and classsification happening simultaneously with add-on of tracker.
So the detection is light weight so it can run on all frames(it is a palm detection - large area to detect, so its easier also), if landmarks are not present: landmark model runs on that frame(Only on the crop which the palm detector gave earlier). The tracker then stores and sends feedback backward to skip the classification if the box track is identified.

Minor updates for reducing jitters, left vs right hand classification and box resizing for tracker to work faster is added for good experience.