Backend engineer — Go & Java. I build the parts of an LLM application that have to survive production: retrieval quality, agent orchestration, failure degradation, observability, and security boundaries.
Hong Kong
| Area | In practice |
|---|---|
| Retrieval & RAG | Hybrid retrieval over pgvector / Elasticsearch / Qdrant · citation traceability · visibility filtering · degrading gracefully when a backend is unavailable |
| Agent engineering | Tool orchestration · MCP servers and clients · prompt lifecycle and versioning · structured-output contracts |
| Production hardening | End-to-end tracing · LLM cost accounting · tenant and permission boundaries · CI quality gates |
OmniCraft · Go · Next.js · PostgreSQL/pgvector · Redis Streams A content-sharing platform whose core is a server-mediated, single-agent RAG workbench: citation re-checking, visibility filtering, degradation-capable hybrid retrieval, and a transactional-outbox async pipeline. Ships with offline evaluation, security gates, and full-trace observability.
polyu-agent · Spring Boot 4 · pgvector / Elasticsearch · React · polyuguide.com A bilingual Q&A agent for campus information at PolyU (unofficial). Domain-partitioned knowledge bases, citation traceability, and scheduled content refresh on a deterministic ingestion pipeline.
health_agent · Java · Spring Boot A unified health assistant covering three product categories. Deterministic multi-role workflow orchestration driven by an explicit state machine, contract-based degradation, hybrid-retrieval RAG, and an MCP server surface — backed by 900+ automated tests.
ppp-rpc · Java · Netty · ZooKeeper A lightweight RPC framework built from the wire up: Netty transport, ZooKeeper-based service discovery, three load-balancing strategies, and retry policies.
Also built
- jewel-ar-tryon — technical PoC for AR jewelry try-on in a WeChat Mini Program.
- Proactive-Diet-Shopping-Assistant — Expo / React Native shopping assistant: barcode and vision recognition, allergen conflict detection, nutrition-compliance scoring.
- ADA_Project — short-horizon air-quality forecasting: multivariate time-series ETL, feature engineering, multi-model comparison over the Open-Meteo API.
- ppp-blog — Halo 2.x blog stack: Docker Compose deployment, GitHub Actions CI/CD, monitoring and alerting.
Contributions to projects I depend on:
- docling-project/docling-core #766 — Markdown table serialization: row-header rows no longer leak into the table header block.
- elastic/beats #53159 — corrected wording defects in user-facing error messages (filebeat, winlogbeat).
- nageoffer/ragent #131 #132 #133 #136 — document-ingestion hardening (outbound validation, response size caps, no error-body echo), upload-endpoint rate limiting, parser/module cleanup, and a flaky-CI fix in the trace test suite.
- Languages — Go · Java · TypeScript · Python
- Backend — Spring Boot 4 · Gin · Netty
- LLM / Agent — RAG (pgvector · Elasticsearch · Qdrant) · agent orchestration · MCP · DashScope / MiniMax / DeepSeek
- Data — PostgreSQL · MySQL · Redis / Redis Streams
- Frontend — Next.js / React · React Native
- Engineering — Docker · GitHub Actions · OpenTelemetry
- Live product — polyuguide.com