During November 2024, Kirill Benua focused on enhancing error handling reliability in the swiftlang/swift-foundation repository. He addressed a bug related to CustomNSError errorDomain naming by refactoring the calculation method to use _typeName(self, qualified: true) instead of String(reflecting: self). This technical approach improved the accuracy and stability of error domain names across modules, reducing the risk of misidentification during debugging. Working primarily with Swift, Kirill applied his expertise in error handling and Swift development to deliver a targeted, high-quality code change. The work demonstrated thoughtful attention to cross-module consistency and contributed to more robust error identification in Swift Foundation.