Singular

Summary
You need to control all the robots. If you have the the Kingmaker achievement it means you can then get Singular. There's also a method in the autonomy path, but by the time you reach it you need your grace to be higher than your autonomy, and then tell your robot to control all the robots. Then in the last scene when you're given the surgery options choose "I have a better idea. I will join the hive mind."