New Delhi, Jan. 7 -- Robot vacuums have spent years chasing bigger numbers, with brands pushing more suction, more "AI" in the app, and more object detection. But the thing that still ruins the experience is basic. Many of them get stuck on the small transitions between rooms.

And the most common way they fail is embarrassingly small. They cannot get from one room to the next without help. Most homes have at least one problem spot, a raised doorway lip, a transition strip that has been there forever, a thick rug edge that catches wheels. It is the kind of thing you step over without noticing, but a robot hits it, shuffles, then gives up. That is how "whole home clean" turns into "half the house, then an alert".

Roborock's Saros 20 and S...