During June 2025, Harukawa contributed to the increments/qiita-cli repository by updating React component type definitions to support potential null values for HTMLDivElement references. This work addressed compatibility requirements for the upcoming React 19 release, ensuring that the codebase could safely accommodate changes in ref handling without sacrificing type safety. Harukawa’s approach involved careful adjustments in TypeScript, focusing on forward compatibility and migration readiness. The changes provided commit-level traceability, allowing for clear documentation of the migration process. This feature work demonstrated a focused application of front end development skills, with attention to both technical detail and future-proofing the project.