AI Engineer · Agent Builder
Ethan Yan
I build AI agents that earn their place.
Engineer working on agentic systems — the planning, memory, and tool-use that make models genuinely useful. Ten years from backend to full-stack to AI. I care about software that feels calm, fast, and honest.
Building agent systems in public · 2026
Selected work
HR Agent A production HR / recruiting agent that writes code in a sandbox to call primitives (code-action), handling talent workflows end to end.
pdf2md A document-parsing pipeline that turns messy PDFs into clean, structured markdown for downstream LLM use.
Smart Building Report A three-stage AI construction-report pipeline (image/task recognition → unit reports → builder reports) over Java + Python + RabbitMQ + an LLM gateway.
Model gateway & observability A LiteLLM-based, OpenAI-compatible gateway unifying GPT / Gemini / Claude with routing, retries, fallback, and caching — paired with Langfuse for end-to-end call tracing and cost observability.
LLM evaluation platform Multi-model × multi-prompt evaluation with LLM-as-Judge scoring, batch runs, and resume-on-failure — built on the same LiteLLM + Langfuse stack.
pingcode-mcp An MCP server that bridges the team PingCode project-management tooling to agents. 
SwiftMind Systems 
Internet hospital Backend for online consultation and appointment booking — interface development, business logic, and on-call stability work.
Distributed bank custody system A high-concurrency financial transaction platform across upstream banks and downstream businesses — 30M+ transactions/day at 99.99% uptime, with JVM/DB/cache tuning lifting throughput ~80%.
Personal projects
OpenFix A local macOS agent that diagnoses and fixes Mac & network problems — no jargon, just answers. ReqBridge Turns vague product requirements into structured, build-ready specs. TrendRadar Aggregates trending topics into a daily AI digest of what is moving. claude-code-rev Took Claude Code's source apart to understand the agent harness.
Recent writing
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