I was trying for example with the following section in the `magic/sky130A.tech`:

router
layer1 met1 20 met1 40
layer2 met2 20 met2 40
contacts m2c 30
gridspacing 30
end

My manually edited net-File looks as follows:

Net List File

top_0[0]/A
bottom_0[0]/A

top_0[0]/B
bottom_0[0]/B

top_0[1]/A
bottom_0[1]/A

top_0[1]/B
bottom_0[1]/B

Then, the

route

command connects all pins on metal1 but doesn's care about short circuits betweeen different nets.

I would not suggest trying to auto-route with magic's primitive router. You will have better results with the maze router ("mzrouter" section, style "irouter"), although even that isn't the world's greatest router.

Thanks for the guidance! I'll try the maze router.