Worked on enhancing reliability and maintainability across two repositories, focusing on robust API development and data validation. In the langgenius/dify project, improved testing infrastructure and code quality by refining API validation, migrating query parameters to Pydantic models, and cleaning up type hints to streamline future development. For mib1185/homeassistant-core, addressed an IndexError in the Israel Rail sensor by introducing guard logic, ensuring the sensor returns an unknown state when data is missing, and improved configuration management by explicitly passing config entries. Leveraged Python, TypeScript, and asynchronous programming to deliver features and fixes that strengthen backend systems and developer experience.