During August 2025, Oleksii Chernyavskyi enhanced the GreenCityUser and GreenCity repositories by delivering modular Azure Cloud Storage integration and expanding test coverage to reduce regressions. He refactored AzureCloudStorageService to extract a dedicated AzureBlobClientFactory, improving modularity and testability using Java and Spring Boot. Oleksii also introduced comprehensive unit tests with JUnit and Mockito, covering user services, exception handling, and language validation. His work included integrating clearer error responses for JSON parsing failures and refining authorization handling in GreenCity controllers. These contributions improved reliability, maintainability, and error transparency across the backend, demonstrating depth in backend development and cloud storage integration.