Jiyu Yan

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Home Page About Page Projects Page CV Page Dev Page Journal Page Contact Page Astro for Documentation and a Professional Site Dev Codex anywhere with tmux, Mosh, Termius, and Tailscale Dev Observing Codex MCP Tool Calls with Langfuse Dev Localization in Product Apps Dev MCP as a Safe AI Integration Boundary Dev Zod, OpenAPI, and Swagger for API Contracts Dev pg-boss for Durable Background Jobs Dev pgvector and RAG, Explained Through a Real Knowledge Workflow Dev Pragmatic Drag and Drop for Real Ordering Tasks Dev Prisma and PostgreSQL as the Product Source of Truth Dev Ralph Loop as a Plan Queue Dev React Router for Full-Stack Product Workflows Dev shadcn-Style UI as an Owned Product System Dev Dense Operational UI with Tables and Editors Dev Terminal Spike: a Native Android Terminal Dev Input Chinese pinyin with tones on Linux with fcitx Dev How to configure the DEFT Pro trackball on Linux Dev Use Pocket (read it later) on KOReader Dev Vercel AI SDK with Explicit Tool Boundaries Dev Vertical Slice Architecture with Dependency-Cruiser Dev Testing Product Workflows with Vitest and Playwright Dev Zod Beyond Validation Dev The Brothers Karamazov is the best novel I have ever read Journal Oral history of two Christians in a Chinese labour camp in the 1960s Journal The Word in the Bible Journal We love because He first loved us, not meaningless self-love Journal Mom, let me take the blame for Dad's mistakes Journal My story with God Journal The world is far from God, close to China Journal The Five Love Languages and Extrovert Only Exist in Language Journal Personality types don't exist, life is not a matching game Journal Dangerous words, why psychology is impossible Journal The story of a Shenzhen worker in 2000 Journal A Conversation with a Driver in Ras Al Khaimah Journal Shadian: a 1975 conflict between Communist forces and Muslims in China Journal Documentaries About China Journal
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A fencer suspended mid-leap, foil extended.

Hi, I’m Jiyu.

A software engineer in Wrexham, UK.
I build useful products, integrations, and developer tools.

Explore my work About me

01 / Selected work

From idea to everyday use.

All projects
Terminal Spike / AndroidTerminal Spike running a remote coding session on Android

Terminal Spike

Android · SSH · Developer tools

A remote workspace that fits in your pocket.
OpsDesk AI / Product demoOpsDesk AI service desk with enquiry triage and human approval controls

OpsDesk AI

AI · Operations · Full stack

AI-assisted operations with people in control.

Ralph Loop

Reviewed plans. Focused agent runs. A calmer development loop.

TypeScript / CLI

02 / From the workbench

Things learned along the way.

All Dev posts

Terminal Spike: a Native Android Terminal

An Android SSH client for remote work, with tmux sessions, SFTP, configurable controls, and a short demo of remote coding from my phone.

Observing Codex MCP Tool Calls with Langfuse

A practical local setup for tracing Codex MCP requests, tool execution, and evaluation without sending application data to the cloud.

pgvector and RAG, Explained Through a Real Knowledge Workflow

A plain-English walkthrough of how Markdown knowledge pages become searchable AI context using embeddings, pgvector, HNSW, and evaluation checks.
Beyond the code

Books, faith, and a few observations on being human.

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