Removing the step where customers type their AWS account number — a CloudFormation custom resource that mails the role ARN to an SNS topic, an SQS buffer, a server that treats the notice as a hint and proves it by assuming the role, and the replies, retries and open-mailbox risks that come with it.
Connecting a customer’s EKS cluster without taking any long-lived key — a per-team ExternalId against the confused deputy, a role template that can only register itself into chosen namespaces, the k* pattern that slipped past a kube-* deny, 15-minute tokens, and the address check that blocks private endpoints.
Moving the VPC and Aurora that predated Terraform out of a CloudFormation stack — how fourteen resources split into two roots, the two apply roles built for them, and the IAM gaps that eight review rounds found before anything was applied.