A developer who digs until the "why" is answered

Hello, I'm Yechan Kim.

Diene ich ihm nicht recht, so zerbricht es, oder es zerbricht mich.

If I do not serve it rightly, it breaks, or it breaks me.— Martin Buber, I and Thou

Yechan Kimnerdchanii

I build tools around what to hand to an agent and what to ask a person.
This is where I write it down.

The year I started computer science

Stories found 0 / 5

2020 · 1 record

SchoolKorea National Open University, Computer ScienceSeptember 2020 to February 2023.

2021 · 1 record

StartFirst GitHub profileStarting with small config files and practice repositories.

2022 · 2 records

ProjectCodeSparringMy first toy project: solving coding tests together in real time.I built a service where people solve the same problem together in real time, so preparing for coding tests alone would be less dull.

Librarysocket-storeA small library for handling WebSocket state in React.Published to npm as a framework-independent core (socket-store) and a React adapter (react-socket-store).

2023 · 3 records

ProjectRPMA Node package manager written in Rust. Still ongoing.I implement install, dependency resolution and script execution in Rust one at a time, and experiment with fixing the behavior in a spec document first.

GraduationGraduated from KNOU Computer ScienceFebruary.

42 SeoulJoined the 10th cohortOctober. 100 peer evaluations during the Piscine.

2024 · 3 records

42 SeoulminishellA shell that behaves like bash, built by two of us. I wrote the executor.I took the commands the parser handed over and handled fork and exec, pipes, redirections and signals. I also wrote the heredoc input and the exit status handling.

42 Seoulcub3DA 3D maze drawn with raycasting.

42 SeoulircservAn IRC server in C++. Until early 2025.

2025 · 3 records

42 Seoulft_transcendenceA multiplayer web game built as a team.

BoostcampAI Tech 8th cohort, NLPStarted in September, with MRC and ODQA.

NotesMath and reading notesDerivatives, eigendecomposition, PCA, Debugging Teams.

2026 · 6 records

BoostcampMITAn agent that works with meeting records. I owned the agent part.Human approval is required only for tool calls that change data. The tool call that asked for the time on every turn was removed by putting the current time in the system prompt.

Open source5 SolidJS PRs mergedsolid-cli and templates.I showed with a reproduction repository that router state leaked between concurrent SSR requests, and the fix that creates a router per request was merged.

Devlog2026-07-17When One Cache File Made Codex Behave Like Two Different ProductsI started with a simple but confusing symptom: Codex subagent tools were unavailable in some sessions, even though multi-agent support was enabled. In one…

Retrospective2026-03-24Goodbye, 42 Seoul42 Seoul 캠퍼스가 문을 닫는다는 소식을 접했다. 아쉬운 소식이었다. 하지만 그 소식을 계기로, 지난 42서울에서의 시간을 한 번 정리해 보고 싶어졌다. 42서울에 10기로 2023년 10월에 입과했다. 시간으로는 그로부터 2년 반 가까이 흘렀지만, 실제로 가장 밀도 있게 활동한…

Retrospective2026-04-01지난 최종프로젝트 기간을 돌아보며피리부는 사나이 만화의 제목이기도 하지만, 드라마 실리콘밸리에서 유니콘 스타트업이 된 주인공네 회사 이름이기도 하다. 종종 싸우고 부딪히지만 서로가 유기적으로 연결되는 조직을 보며 멋지다고 생각했다. 드라마를 보면서, 나중에 저렇게 협업해보고 싶다는 생각을 했었다. 이번 프로덕션…

Retrospective2026-03-24수능형 문제 풀이(MCQA)이번 프로젝트는 생성형 모델을 활용한 「수능형 문제 풀이 모델 생성」이었다. 국어/사회분야의 다지선다 문제를 푸는 MCQA(Multiple-Choice Question Answering) 테스크였다. 프로젝트 초반에는 EDA 보조와 FastLanguageModel 기반 학습 환경…

That's the record so far.