During August 2025, contributed to the GreenCityUser and GreenCity repositories by delivering modular Azure Cloud Storage integration and enhancing backend reliability. Refactored the AzureCloudStorageService to extract a dedicated client factory, improving testability and maintainability. Expanded unit test coverage for user services, exception handling, and language validation, using Java, Spring Boot, and Mockito to ensure robust error handling and clear client responses. Integrated custom exceptions to standardize BAD_GATEWAY error messaging for JSON parsing failures. Improved authorization logic in controller argument resolution, adding comprehensive tests for principal handling and unauthorized scenarios, while maintaining readable, consistent test suites through targeted cleanup and formatting.