LinkMode

type LinkMode = 
  | "prefer-horizontal"
  | "prefer-vertical"
  | "horizontal"
  | "vertical"
  | "auto"
  | "top-bottom"
  | "bottom-top"
  | "left-right"
  | "right-left";

Chooses which side of an element or port a link attaches to when using the mid-side anchor. 'auto' picks the side nearest the other end; 'horizontal' and 'vertical' lock to left/right or top/bottom; the 'prefer-*' variants favor one axis but fall back to the other; and the directional pairs ('top-bottom', 'left-right', etc.) pin the source and target to opposite sides.