Worked on reliability and developer experience improvements across vechain/vechain-kit and vechain/vechain-sdk-js repositories. Delivered a feature to harden subscription polling against network variability by upgrading thor-devkit, enhancing error handling, and updating documentation for clearer integration guidance. Addressed a critical bug in account version queries by introducing a safety guard that prevents execution when required parameters are undefined, reducing runtime errors and unnecessary API calls. Applied JavaScript, TypeScript, and React to implement robust null guards, optional chaining, and modernized test runners, focusing on both front end and full stack development with an emphasis on code quality and maintainability.