Worked on restoring backward compatibility for the Date.now API in the swiftlang/swift-foundation repository, focusing on legacy versions of macOS, iOS, tvOS, and watchOS. Addressed a compatibility bug by re-adding deployment attributes in Swift, ensuring that existing applications could continue to use Date.now without requiring major code changes. Maintained API parity across platforms, which reduced migration risks and allowed for safer rollouts on older operating systems. The solution was implemented with a minimal surface area, prioritizing lightweight changes. Demonstrated expertise in cross-platform development, Swift, and Apple ecosystem development, with a focus on stability and long-term maintainability for existing codebases.