Every roadmap bet needs a kill condition

Before we build a feature, I want one observable result that would make us stop, simplify, or change direction. Without that, every weak result becomes an argument to add another feature.

A kill condition is not pessimism. It protects the team from negotiating with the evidence after time and ego are already invested. The hard part is writing it before the build begins, when changing your mind is still cheap.

What condition would make you stop your current roadmap bet?