gl.sketch overlapping shape problems at z=0

I am playing with hexagon tilings in jit.gl.sketch. I want to sketch some overlapping shapes at z=0. I can draw a circle in six 60-degree arc segments and I get a seamless circle. But if I draw that same circle on top of hexagon slices, I see gaps between the arcs in the circle.

I could fix this by making the circle a little closer to the camera, but I want to stay at z=0 so when I translate the tile the circle stays centered in the hexagon.

In my patch, use the number box to send 6 consecutive numbers. The problem happens in the center. To either side you can see the circle drawing properly. On the right, the unwanted z-translation makes the circle go off-center.

How can I draw overlapping shapes at z=0 and avoid the seams?

-Adam