Worked on backend and configuration enhancements across two repositories, focusing on API development and system configuration using Go and YAML. In traPtitech/Jomon, simplified the Tag API by removing the Description field from tag request payloads, updating the test suite to maintain coverage and reduce maintenance overhead. This change improved API clarity and streamlined frontend integration. In traPtitech/manifest, extended the configuration management system by adding a GPT-4.1-mini model option to config.yaml, enabling runtime model selection and supporting flexible experimentation. The work emphasized maintainability and scalability, ensuring that new features could be integrated with minimal disruption to existing workflows.