Product-minded Backend Developer
I care about the product, the people using it, and the business behind it.
I work on education and AI-powered services, from initial development to day-to-day operations and ongoing improvements. I also build service backends and developer tools.
| Project | What it does |
|---|---|
| TTYRoom | Share local terminal sessions in the browser, with input control and reconnect recovery. Spring Boot · React · WebSocket · PTY. Demo · Design & tests |
| ledger-relay | A Java/Spring library that relays commands from a PostgreSQL outbox to TigerBeetle in order for each key, using ledger outcomes to decide what happens next. In development. Sample shop |
| overlapmark | Overlapping text highlights for any framework: the more highlights cover a spot, the darker it gets. TypeScript · Vue · React · Svelte. Demo · npm |
| Semantic Context OS | Long-term memory and retrieval for AI agents, with hybrid keyword/vector search and MCP access to team knowledge. Work in progress. |
| Donghyun's Agent Tools | Reusable coding-agent plugins for browser QA, UI comparisons, prototype intake, and keeping specifications aligned with code. Plugin guide |
For ledger-relay, I set the design direction and review the work; Claude Code writes the implementation, tests, and documentation.
- Hoogle · A preserved copy of a team project for Doc2Vec-based article search. Runtime restoration is still needed.
- English problem generator · A preserved copy of a Python/NLP team prototype for generating English questions. The model and runtime environment still need restoration.
- Learning archive · University coursework and personal programming exercises.