Postmortem

Postmortem: the agent that spent $200 retrying a 400

An agent burned ~$200 overnight retrying an HTTP 400 — a request that was defined to fail. No component was buggy; each layer retried “reasonably.” The teardown: why retryability is a property of the error and not a default, how three nested retry caps multiply into 75 doomed attempts per item, and why per-step caps never bound a bill. With the two-line fix and a circuit breaker.

Loop drift: how agents convince themselves they're making progress

The worst agent failures don’t crash — they keep working. A postmortem on loop drift: an agent that stayed busy for 40 steps without getting closer to done, why the model’s own progress reports can’t catch it, and the external signals and evals that can.