SVG marker-mid on specific point on path

Question

I got some code that generates pathes on canvas. the path objects looks similar to this :

Answer 1

The marker-mid defines the arrowhead or polymarker that shall be drawn at every vertex other than the first and last vertex of the given element or basic shape.

You are drawing a line with vertices A, B, and C, so by definition the marker will be drawn at B.

If you want a marker to be drawn between A and B you will need to draw a path from A to the midpoint AB to B.