Tools api update callback?

How does a tool know when something outside the tool’s own code is modifying a mesh in edit mode? Is there some kind of callback I can subscribe to? For example, I noticed that the loop cut tool updates its BVH tree for raycasting after the grab operator moves part of the mesh- though I’m not sure what’s triggering the update. You can tell that the preselect loop lags behind for a second. Is it just continuously updating during the mouse move event? that seems… inefficient.