The automated dev container image caching feature accelerates environment startup by leveraging automatic image caching. This approach eliminates the operational overhead of manual prebuilds, provides better security through fine-grained IAM project isolation, and offers improved lifecycle management with automatic 30-day expiry. The system automatically caches images for identical configurations, speeds up build times from minutes to seconds, and preserves additional configuration adjacent to the build. It also ensures that dev container features like Docker-in-Docker work seamlessly whether starting from a cached image or building fresh. Additionally, it separates shared project configuration from user-specific personalization, providing security, team efficiency, and cache effectiveness benefits. The feature is available for AWS runners today and offers significant performance improvements, including reduced context switching costs, faster onboarding, ephemeral environment adoption, and improved AI agent performance.