Ethan Chen

I build AI agents that people use at work, and I measure whether they help.

Yixuan (Ethan) Chen, Applied AI undergraduate at the University of Hong Kong. Available for internships from December 2026.

See the workEmail me

Work

  • Shipped at a company
  • Research
  • My own products
FirmGround answering an audit question, with the cited PCAOB paragraph highlighted in the source document

FirmGround, my own product

FirmGround Agentic RAG

A research agent for document-heavy work. It searches standards, filings and textbooks, runs any arithmetic in code, and cites the passage behind each claim. 81.33% on FinanceBench, against 21.33% for naive RAG.

ReAct agent, hybrid retrieval, FastAPI, Taskiq, OpenSearch

Read the case study

How I check my own work

Before I trust a component, I test it on a set built to break it. These three results decided what I shipped.

Picking a claim verifier

X-ray screening reports need a verifier that catches claims the evidence doesn’t support. I chose it on a benchmark I built, not on a leaderboard.

AUROC at flagging unsupported claims
TypeSafe Jev (chosen)
0.988
Best open-source (Kev-4B)
0.924

200 simulated reports, 921 claims, 20 types of planted error.

X-ray screening reports

Testing the RAG agent

Same model and embeddings as a naive RAG baseline. The only change is the agent loop and its retrieval tools, so the gap is theirs.

FinanceBench accuracy
FirmGround agent
81.33%
Naive RAG
21.33%

FinanceBench open set, 150 questions over public company filings.

FirmGround Agentic RAG

Checking tool routing

Hiding tool schemas saves tokens only if the agent still picks the right tool, so two thirds of the cases were written to be confusable.

60 of 60 tool calls correct

confusable case (40) standard case (20)

60 tasks across 83 tools.

One gateway for 83 tools

About

I’m Yixuan Chen, and I go by Ethan. I study Applied AI at the University of Hong Kong. Most of what I’ve built started from someone else’s slow task: claims handlers preparing case files, accountants reconciling statements, a school searching its own textbooks. I like the part where a tool leaves the demo and becomes something people keep using.

I’m a student adviser for the Applied AI programme and present at student-led GenAI seminars.

Languages
Putonghua (native), English (fluent, IELTS 8), Cantonese (fluent)
Honours
Dean’s Honours List 2025 and 2026. Entrance Scholarship
Works with
Python, SQL, LangChain, LangGraph, MCP, PyTorch, FastAPI, PostgreSQL, Redis