Simply delete 27 genes from part of chromosome 7. https://en.wikipedia.org/wiki/Williams_syndrome

Dogs were bred with this friendliness to be willing laborers with their own safety being a secondary concern to doing a job given to them. Think of how quickly and eagerly this would be used by those who want exploitable labor from humans.

In a few generations' time, we might have capable enough robots.

And self-replicating robots at that! They will just require food, water, and shelter as inputs.

“The best computer is a man, and it’s the only one that can be mass-produced by unskilled labor.” Wernher von Braun

The initial thing though, before what you’re describing, is just getting dogs that are friendly enough not to try and eat you.