Understanding AtMostOncePerRetry vs AtLeastOncePerRetry in AWS Durable Lambda

For a durable Lambda function, standard errors at any step are checkpointed and handled during the next replay by retry-strategy configurations. However, there can be scenarios where a durable step starts execution but fails to complete, while also leaving no ERROR checkpoint behind. A common example is a Lambda execution timeout. In such cases, step semantics become important because they define how the workflow should behave when the system cannot determine whether the step completed successfu