The tests are green. The build passed. And somewhere in that diff is a product decision you didn't make, a file that was never in scope, and a behavior that will surprise you in three months. FST catches all of it before you merge.
A blocked gate is not a failed build. It is a specific finding with a specific resolution. The agent's work is not lost. You are told exactly what is missing and exactly how to fix it.
An AI run that fails is not automatically wasted work.
It becomes wasted work when nobody can tell why it failed, what was learned, and what the next attempt is allowed to do differently.
Speed is easy.
Consistency is not.
The failure shows up late.