Your agent doesn't crash when it goes off the rails. It just keeps billing you[p]

Excerpt

It doesn't throw. It doesn't return malformed JSON. It just quietly stops doing what you asked — losing the thread, repeating itself, answering a question nobody asked — and keeps burning tokens for every step after that. Constrained decoding guarantees the shape of the output. It has no opinion about whether the agent is still doing the work. So I built a detector for that and open-sourced it: from driftguard import AgentWatch watch = AgentWatch(task="the objective you gave the agent") for step