Seohyeon Chang

CH-1 ▶ DEV — software / systems

■ workしごと

Imaginal Games 2025.06 – present

AI engineer / early team member — seoul · AG1 accelerator, Tokyo

dr-dr — real-time LLM agents

Built the real-time agent framework from concept to a playable build: structured commands execute during generation after validation against current world state. In a 32-call evaluation, compact action encoding reduced completion tokens 42%, cost 28% and latency 16%, with all state checks passing.

deathhammer — voice agents, localization & agent playtesting

Co-developed voice and chat agents for 40 NPCs, with per-character memory and streaming ASR averaging 245 ms. Built a localization pipeline for about 2,500 strings that won 95% of blind comparisons. Co-built a 22-tool MCP bridge for coding-agent playtests across up to 28 parallel sessions: 356 episodes and 121 unique bugs in 3 days. Feedback from 6 SOOP streamers informed a slower in-game clock.

deathhammer — pixel art & cutscenes, persona prompts

a story-driven pixel-art game where NPCs hold real multi-turn conversations. i run the art team — making the in-game pixel art and cutscenes through an AI-generation pipeline i built — and write the persona prompts that keep each NPC in character. minigames & prototypes on the side.

in-game sprites, exported from my aseprite files. cutscene reels coming once the game ships.

unwanted guests — AI bartending sim (C# / unity)

a browser bartending sim: pour drinks and hold free-form conversations (typed or spoken) with AI-driven regulars. cook AI-generated dishes, manage each guest's mood — say the wrong thing and the night goes sideways.

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rumor weavers — NPCs that gossip (python / gemini)

an LLM-driven NPC town where rumors spread on their own. what a player does gets extracted into structured events, seeded as firsthand knowledge, and propagated along the relationship network by bacon distance — witnesses recount it confidently, friends-of-friends hedge, and three steps out it dissolves into vague hearsay. gemini-based, with fast/slow-lane embedding routing for dialogue.

simple pixel snapper — video → pixel-snapped GIF (rust)

internal macOS tool: drop in a video, get a grid-stable pixel GIF out, colors optionally matched to a reference palette. built because our cutscene pipeline needed it.

» github

Squidly 2026.09 – present

game developer intern (part-time) — sydney

Building Guide Me Home, a browser AAC therapy game for children with motor disabilities, with Royal Prince Alfred Hospital clinicians. Click-only input supports eye-gaze and switch users. Weekly reviews shaped 5 chapters, 24 tasks and 3 difficulty tiers; 255 automated tests cover the game.

Jacaranda Flame Consulting, University of Sydney 2026.06 – 2026.07

student consultant (software) — sydney

Led software in a 5-person cross-functional team building an assistive switch for Squidly. Built ESP32-C6 firmware and a Python asyncio BLE-to-WebSocket bridge, fixed a macOS HID descriptor bug, and delivered dual-mode firmware plus setup and API documentation. Squidly later recruited me as an intern.

Mercor 2026.02 – 2026.06

AI data evaluation expert (contract) — san francisco, remote

Evaluated LLM outputs for hallucinations, factual errors and instruction-following failures.

■ personal projectsつくったもの

VLOOM — VTuber subscription messaging / 2026.06 – present

Founder and sole engineer of a pre-launch fan-messaging platform. Built Next.js and React Native clients with NestJS, PostgreSQL, Redis and BullMQ; broadcasts use idempotent 500-recipient jobs and SSE updates. AWS CDK infrastructure and CI support 180 API test suites (3,438 assertions). Across an 80-case moderation benchmark of 5 LLMs, prompt revisions raised accuracy from 88.7% to 98.8%, with 0 misses and 0.25 s p50 latency. Set pricing and a 70% creator revenue share.

KRAFTON AI R&D hackathon — autonomous agents / 2026.10

Individual entry using a coordinated AI coding-agent workflow. Built a 10 Hz navigation agent and an evaluation harness covering 23,517 simulated episodes; ranked 6th of 71 on the hidden leaderboard. Reduced a video world model to 1.0M parameters and its ONNX encoder from 118k to 9k nodes; RTX 3090 p95 inference was 15–29 ms per frame.

AI worldbuilding platform — university capstone / 2026.08 – present

AI pipeline owner on a team RAG project. Built generation jobs with credit reservation, bounded retries and lease recovery verified by SIGKILL tests, plus a prompt envelope for untrusted retrieved context.

JamMate — Django / 2026.09 – present

Team web app for musicians: profiles, jam sessions and join requests. Contributed 43 of 45 commits and built 42 tests.

autonomous ML research harness — Kaggle RSNA / 2026.09

Built a sandboxed coding-agent research harness with allowlisted tools, preregistered kill/promote rules, a hash-chained ledger and a 180 GPU-hour budget. Reproduced two public baselines (0.928, 0.936) and stopped a 0.922 ensemble under its rule.

GazeAAC — predictive text evaluation / 2026.06 – 2026.07

Compared GPT-2, GPT-2 Medium and Qwen2.5-1.5B on 1,300 next-word records (top-1: 23.0%, 28.0%, 35.3%). After accounting for selection, review and correction costs, confidence gating did not beat manual entry on held-out records.

persona framing in language models / 2026.01 – 2026.07

Studied 5 personas across 8 tasks with Qwen2.5-1.5B-Instruct. No-persona controls exposed a lexical confound; a follow-up of 108 generations across 3 framings found no detectable difference.

six people, one meeting — toss designer challenge 2026

when six people schedule a meeting, the kindest person always loses — tools like when2meet flatten "can't" and "would rather not" into one painted cell, in public. this one lets you block real conflicts privately and swipe candidate slots by preference, then picks the fairest time (actual maximin) — asking only the single most-inconvenienced person, anonymously.

» live demo · github

Dalligo — cycling & social app (Flutter / Firebase)

Product planning, UX and development in a team of 4 (2026.05–present). Released on the App Store in August 2026 and Google Play in September 2026. Built segment leaderboards, crew territory competition, challenges, push notifications and feed search; contributed 207 of 490 commits.

letsnote wheelpad — kuru-kuru scrolling on linux (python)

panasonic let's note laptops have a circular wheel pad, but wayland's libinput never supported the signature kuru-kuru scroll. this daemon restores it at the evdev/uinput layer — telling real rotation gestures apart from wandering pointer moves, with a systemd watchdog so a crashed daemon can't take the touchpad down with it.

» github

pointerpro animate — 2D graphics library (C11)

a modular 2D graphics/animation library in plain C11 — O(1) spatial layer operations on a custom doubly-linked list, zero leaks and zero segfaults across the test suite under AddressSanitizer.

charlie — autonomous multi-tool agent

an agent that plans and executes across 23 external APIs, then checks its own work — a self-correcting loop that re-plans whenever a result looks wrong.

■ education & skills

The University of Sydney 2024.07 – 2028.06 (expected)

Bachelor of Engineering (Honours), Computer Engineering. WAM: 77.8/100 (Distinction). Sydney International Student Award. English: CEFR C1.

Python · TypeScript · JavaScript · SQL · C/C++ · Java

PyTorch · Hugging Face · FastAPI · Django · NestJS · Next.js · React Native · Flutter

PostgreSQL · Redis · BullMQ · Docker · AWS CDK / ECS Fargate · GitHub Actions

LLM agents, RAG, model evaluation, latency profiling, CI/CD, accessibility, user research and product planning.

CH-2 ▶ VIDEO — moving image / photographs

■ videoきろく

YouTube creator, 2018–2023. Edited K-pop Shorts reaching 81.6M lifetime views and 18.5k subscribers; an earlier Minecraft science channel reached 6.5M views.

TAPE 01 — FIXION demo · imaginal games