This was a fun workshop! Thanks for sharing! Just to let you know, in the invokeFutureSNSStatemachine lambda function, I had to concatenate the state machine ARN with the env variable to make it work. In the CDK part, we create the state machine with dev env appended at the end. Also, since my AWS account is in the SMS sandbox, I had to specifically set the destination phone number. However, I could have requested production access.