Have you considered a drainboard? Here is a sink with runnels on the right, and a drainboard on the left. You have to clean the runnels which, depending on how big they are, can be a chore. The drainboard is easier to maintain. Both begin and end at the top and bottom of the sink cutout so that liquids drain into the sink. That’s usually at least 18”, but your guy will have those measurements.

Or consider a farmhouse sink that has the workstation components:

https://www.perigold.com/kitchen/pdp/ruvati-33-l-double-bowl-fireclay-kitchen-sink-p110083580.html

Agree with @eam44 that you should consider a drainboard. I had initially wanted runnels in our last kitchen but was talked into a recessed drainboard by my fabricator. It was very easy to keep clean and it worked well.

It does thin and weaken the stone, so beware of doing this with either a hard brittle chippy stone, or a soft scratchy stone.

I'm not drying items directly on the countertop. No runnels.

Thanks everyone i think I will go with the drainboard instead.