Worked on enhancing cross-service Google OAuth authentication in the automatisch/automatisch repository, focusing on improving reliability and user experience across Gmail, Calendar, Drive, Forms, Sheets, Tasks, and YouTube integrations. Addressed authentication edge cases by enforcing account selection and consent prompts, enabling refresh tokens for better token lifecycle management. Standardized OAuth prompt URL encoding by replacing plus signs with spaces, ensuring correct parameter interpretation and reducing token exchange errors. Leveraged JavaScript for backend development and API integration, with a strong emphasis on OAuth2 flows and Google API integration. Delivered these improvements through version-controlled updates, resulting in more robust authentication processes.