In October 2025, János Vesza developed a win-back promotion feature for macOS and iOS within the duckduckgo/privacy-configuration repository, focusing on user retention through targeted re-engagement campaigns. He implemented the solution using JSON and configuration management techniques, enabling the feature to be activated or adjusted via feature flags rather than code changes. This approach allowed for safe, incremental rollouts and facilitated experimentation with retention strategies. By establishing clear configuration boundaries and thorough documentation, János provided a scalable foundation for future retention initiatives, demonstrating depth in configuration-driven development and supporting ongoing QA and release engineering processes within the project.