A circuit breaker is the mechanism that stops work when appetite is exhausted without completion. When a plan consumes its declared appetite and its acceptance criteria are not met, the circuit breaker fires: stop, reassess whether the approach is right, reshape the plan or abandon it.
The concept comes from Ryan Singer’s Shape Up (Basecamp, 2019), where it prevents projects from consuming unbounded attention.
The circuit breaker prevents plans from growing without bound. It forces a choice: is the plan worth reshaping with a new appetite, or should the work be abandoned and the closure pressure addressed differently?