One decorator composes circuit breaker, retry, timeout, fallback, and idempotency, and a built-in console shows every breaker live. Zero-config to start; add Redis and workers share state. Django, FastAPI, Flask, Celery. Apache-2.0 core. tenacity and pybreaker give you the patterns. Baldur also answers what happens when retries run out, who notices a breaker is open, and how you replay a call that failed for good.