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cmun2/README.md

Changyong Mun

Frontend engineer in Seoul, working on real-time, AI-facing interfaces — and on the tooling and writing that make them usable by other people.

Currently at AhnLab, on an EDR security platform. I build the interface for an AI threat-investigation agent: streaming agent reasoning to analysts over Server-Sent Events using the AG-UI protocol, and shipping product modules independently through Module Federation. Alongside that I automate the parts of engineering nobody enjoys — LLM-assisted code review wired through n8n, and architecture diagrams generated as editable draw.io XML rather than dead PNGs.

Selected work

mcp-schema-census — your MCP server is valid MCP and still gets a 400 from the model provider. This tells you why, at which JSON pointer, quoting the sentence the rejection rests on. Backed by a public dataset of 617 servers and 14,804 real tool schemas. Building it surfaced a bug in the official Anthropic Python SDK, which I reported and fixed upstream (#1876 · #1877).

Debugging Arena — frontend accessibility failures turned into playable debugging challenges. A runtime evaluator checks the rendered dialog contract while Playwright verifies that same contract independently, so the exercise cannot quietly grade itself. Built with Codex and GPT-5.6 during OpenAI Build Week. Live demo · Demo video · Devpost

Portfolio — case studies with the reasoning behind each system, not just what shipped.

Writing

An LLM in the Code Review Loop: The Parts That Aren't the Model — 2026-08-10

Streaming to the Browser: SSE for Telemetry and for Agents — 2026-07-13

Module Federation in Production: What Actually Changed — 2026-06-15

Next.JS 변경된 내용이 바로 반영이 안되는 문제 발생 해결 — 2025-04-21

RequestAnimationFrame vs SetInterval — 2025-04-17

More at cmun2.inblog.io — 35+ posts in Korean on micro-frontends, SSE and hydration, CI/CD and testing practice, plus an English series. Each one starts from something that broke in production rather than from documentation.

Recent activity

Pushed to cmun2/unfaked — 2026-08-25

PR openai/openai-node#2463 fix(zod): parse extracted definitions in their property position — 2026-08-25

Issue openai/openai-node#2462 Zod v3: a .nullable().optional() schema shared by two fields is encoded two different ways, and one of them uses not — 2026-08-25

Pushed to cmun2/mcp-schema-census — 2026-08-25

PR anthropics/anthropic-sdk-typescript#1163 fix(schema): keep $defs when the schema root is a $ref — 2026-08-24

Issue anthropics/anthropic-sdk-typescript#1162 transformJSONSchema drops $defs when the schema root is a $ref — 2026-08-24

Stack

AI & real-time — LLM application development · agent event streams (AG-UI) · Server-Sent Events · Model Context Protocol · Codex · Claude Code · n8n

Languages & frameworks — TypeScript · JavaScript · Python · React · Next.js · Vue · Nuxt · Node.js

Platform & quality — Module Federation · micro-frontends · design systems (npm) · Playwright · Vitest · CI/CD

Before frontend I did machine-learning research at CHANGlab, Seoul National University — nanopore RNA sequencing data, FASTQ/BAM/SAM pipelines, and distribution analysis over pandas. It is why schema and data-shape bugs are the ones I tend to notice first.

Contact

LinkedIn · dkdkdkalalal@naver.com

Pinned Loading

  1. cupicks-fe cupicks-fe Public

    Forked from cupicks/cupicks-fe

    이미지만 보고 만드는 카페 레시피 제작 및 공유 서비스

    JavaScript

  2. mcp-schema-census mcp-schema-census Public

    Point mcp-schema-check at your MCP server and see which provider strict modes reject your tool schemas, and why. Backed by 617 servers / 14,804 real schemas.

    Python 1

  3. codex-web-education codex-web-education Public

    A bilingual debugging arena. Repair real frontend accessibility, layout, motion, SSE, and state failures, then prove the fix with independent browser checks — nothing counts until the rendered DOM …

    TypeScript

  4. youtube-live-latency-helper youtube-live-latency-helper Public

    Chrome extension that helps viewers stay closer to the live edge during YouTube livestreams.

    JavaScript