During January 2025, Hyunggeun Lee enhanced the spring-projects/spring-ai repository by expanding OpenAI Text-to-Speech voice options. He implemented new voice constants in Java within OpenAiAudioApi.java, enabling broader TTS capabilities and supporting potential localization. To ensure reliability, he developed parameterized unit tests in OpenAiSpeechModelIT.java, validating that each new voice could successfully generate speech. His work focused on backend development and API integration, emphasizing maintainability and test coverage rather than bug fixes. By linking changes to a specific commit for traceability, Hyunggeun demonstrated disciplined version-controlled development and contributed a targeted feature extension that improves user experience and accessibility.