In light of the GitHub and n8n breaches, the traditional 'persistent workstation' model for developers must be abandoned. The future of secure engineering lies in Ephemeral Developer Environments (EDEs). By moving the IDE and the build tools into a short-lived, containerized environment (e.g., GitHub Codespaces, Gitpod, or internal DevContainers), organizations can ensure that every developer starts with a 'Known Good' state. EDEs allow for the centralized management of extensions, the enforcement of strict egress rules, and the automatic destruction of the environment after the task is complete. This eliminates the possibility of long-term persistence by actors like TeamPCP and ensures that even if an extension is compromised, its impact is limited to a single, isolated session.