Lei Sun – Platform Engineer

> Full-Stack Foundation | PayPal FinTech | Developer Platform | Environment Automation / Multi-Stack / AI Toolchains

Summary

Focused on platform engineering and developer tooling, backed by a solid full-stack foundation. At PayPal, built from scratch a standardized Docker test environment system covering 6 language stacks and 13 e-commerce platforms; a three-layer image caching architecture reduced cold-start times from minutes to under 10 seconds; pushed 30+ multi-arch (arm64/amd64) images to JFrog; packaged a self-service startup tool and Makefile unified interface so AI Agents and engineers can spin up environments without knowing any underlying details. In parallel, built an AI-assisted code analysis toolchain with emphasis on root-cause analysis and pattern documentation, growing a shared team knowledge base rather than individual expertise. Tech stack covers Docker, Makefile, Shell, JFrog, Python, FastAPI, React, Next.js, Node.js, TypeScript, Redis, and gRPC.

Core Competencies
  • Platform thinking — Abstract high-frequency, repetitive, error-prone engineering processes into reusable infrastructure; hide complexity so developers and Agents focus on business logic
  • Multi-stack environment management — Independently built a standardized test environment system covering PHP / Java / Ruby / Python / .NET / Node.js across 13 e-commerce platforms
  • Multi-arch compatibility depth — Systematically resolved arm64 (local Mac) vs. amd64 (CI / cloud) native extension incompatibilities; three-layer image caching architecture is reusable across projects
  • AI toolchain engineering — Built AI-assisted code analysis tools integrating sub-second codebase sampling with multi-model analysis into developer-facing workflows
  • Documentation discipline — Every environment issue gets a root-cause analysis and reusable pattern document; outcomes accumulate as team knowledge, not tribal expertise

Work Experience

PayPal

Full-Stack Engineer | Platform & Tooling | 2024.07 – Present

In 2026, primarily built AI payment migration verification infrastructure from scratch, providing standardized multi-stack e-commerce test environments, automated verification pipelines, and AI-assisted toolchains for AI Agents and engineers.

Responsibilities
  • Designed and implemented a standardized Docker test environment system covering 6 language stacks (PHP, Java, Ruby, Python, .NET, Node.js) across 13 e-commerce platforms
  • Built a three-layer image caching architecture (dependency cache → platform compilation → application image) to solve cross-platform native extension multi-arch compatibility
  • Packaged a self-service startup tool handling environment variable injection, architecture detection, volume pre-population, and database initialization internally — exposing only a few env vars externally
  • Unified platform operation commands (start / stop / reset / test / build) with a Makefile interface, establishing standard engineering conventions
  • Built an AI-assisted code analysis tool integrating MCP with multiple models (Claude / GPT-4 / DeepSeek / Gemini); supports rapid sampling analysis of large codebases and automatic Docker configuration generation
  • Maintained docker-compose-patterns.md and issues-found.md knowledge bases, cataloguing environment engineering lessons ranked by learning value
Impact
  • Delivered a 13-platform e-commerce payment test system; pushed 30+ JFrog multi-arch (arm64/amd64) images supporting fully offline cold starts
  • New platform onboarding time reduced from a half-day of debugging to 1–2 hours
  • Ruby gem cold start reduced from 2 minutes to 10 seconds; Java Maven build reduced from 5 minutes to 10 seconds
  • AI Agents can independently complete environment startup and payment flow verification without human intervention on environment issues
  • Built 60+ Playwright E2E test cases covering the full payment chain: checkout, authorize, capture, cancel, and refund
  • Identified and fixed complex platform issues including OrbStack BuildKit isolated network namespace behavior and VirtioFS nested bind mount silent failures; produced reusable solution documents
  • Contributed to Next.js 12→14 and Node.js 18→20 stack upgrades; delivered Customer Identity Platform (CIP) end-to-end
DockerMakefilePythonShellJFrogPlaywrightNode.jsRubyJavaPHP.NET

Quantex Information Technology (Shanghai)

Full-Stack Engineer | 2024.01 – 2024.06

Led frontend integration for a Disney resort AI digital-human customer service system; initial integration completed in 1 month.

Responsibilities
  • Implemented Web-based 3D avatar rendering, motion and expression control using React, Three.js, and react-three-fiber
  • Integrated Azure ASR / TTS voice sync; resolved iOS / Android WebGL and audio playback compatibility issues
Impact
  • Delivered the first working integration of the AI digital-human system within 1 month, enabling the project to proceed to the demo stage
ReactNext.jsThree.jsreact-three-fiberAzure AISocket.io

Trip.com Group

Senior Frontend Engineer | 2017.04 – 2024.01

Owned Trip.com international Blog / Destinations content channel development and maintenance; drove team React / Node.js tech migration.

Responsibilities
  • Built the department's first Node.js SSR content platform, driving the team's migration from .NET to React / Node.js
  • Long-term ownership of Trip.com international multilingual content channel; continuously optimized Core Web Vitals and SEO
Impact
  • Drove team tech stack migration; established SSR / SEO / Hybrid multi-channel delivery
  • Led 2–4 person frontend sub-teams; established code review standards, engineering norms, and knowledge-sharing culture
ReactNext.jsNode.jsExpressRedisMySQLReact Native

Jiuzhen Network Technology (Shanghai)

Frontend Engineer → Frontend Engineering Manager | 2015.03 – 2017.04

Led React Native cross-platform social app development targeting Android and iOS; managed a 4–7 person frontend team; set up Jenkins multi-branch automated build pipelines.

ReactReact NativeNode.jsPHPMySQLJenkins

Actiontec (Shanghai)

Software Engineer | 2009.10 – 2015.03

Led Hybrid mobile app development for a photo-management product; built router embedded Boa WebServer and management interface; collaborated with US-based cross-timezone teams.

CordovaHTML5JavaScriptJavaLinuxCShell

ZTE Corporation

Software Engineer | 2008.10 – 2009.10

Built alarm module for a 3G network management platform; implemented alarm task processing and desktop client display.

JavaSwingEJBJBossOracle

Gksel Information Technology (Shanghai)

Software Engineer → Technical Manager | 2007.04 – 2008.10

Developed Web projects (rental platform, doctor appointment booking); managed a 3-person technical team.

JavaStrutsSpringPHPJavaScriptjQuery

Jiangsu Jinswei Information Technology

Software Engineer | 2005.04 – 2007.04

Developed and delivered custom enterprise CRM system.

JavaJavaScriptStrutsTomcatMS SQL Server

Projects

PayPal — Multi-Stack E-Commerce Test Environment Platform

2026 | Docker, JFrog, Shell, Makefile, Playwright, Multi-Language Stacks

Designed and built unified test environment infrastructure for the AI payment integration verification team. Goal: any AI Agent or engineer picks up the project and has a running environment within 5 minutes, with consistent behavior across arm64 and amd64.

  • Covers PHP×6 + Python×1 + Java×2 + .NET×2 + Node.js×1 + Ruby×1 across 13 e-commerce platforms with 20+ independent Docker environments
  • Three-layer image caching: taking Ruby as an example — gem-cache (platform-agnostic gem source) → bundle-cache (per-arch native extension build artifacts) → application image; resolves arm64/amd64 native extension incompatibility
  • Offline cold start: npm prebuild-cache (@next/swc, better-sqlite3, etc.) and Maven dependencies pre-bundled into JFrog; containers select by architecture automatically without internet access
  • Self-service interface: only a few environment variables exposed externally; all initialization details (image pull, volume fill, credential injection, database init) handled internally by the tool
  • Makefile unified interface: standardized start / stop / reset / test / build commands across all platforms; AI Agents can invoke directly

AI-Assisted Code Analysis Tool

2026 | Python, FastAPI, MCP, Claude / GPT-4 / DeepSeek / Gemini

Rapid analysis tool for large codebases: samples and analyzes 4,000+ file projects in under 1 second; multi-model collaboration generates code structure insights and Docker configurations.

  • Integrated MCP toolchain for codebase structure sampling, tech stack identification, dependency analysis, and config file generation
  • Supports Claude / GPT-4 / DeepSeek / Gemini multi-model routing by scenario and cost
  • Auto-generates Dockerfile and docker-compose.yml drafts; developers adjust env vars and start

Related personal project: ai-analyze — MCP + Serena-based codebase sampling and analysis tool

PayPal — Large-Scale Merchant Site Scanning

2026 | Python, Playwright, DNS, HTTP, Data Analysis

Layered scanning of hundreds of thousands of merchant URLs to identify legacy payment integration sites, supporting business team migration decisions.

  • Three-layer architecture: DNS pre-check + HTTP static scan + Playwright deep exploration — progressively filters invalid targets
  • Identified thousands of legacy WPS payment integration sites; analyzed integration pattern distribution (auto-submit / encrypted / hosted / cart)
  • Integrated three-source threat intelligence (URLhaus / Phishing.Army / HaGeZi); auto-filtered malicious sites
  • Produced structured multi-category site datasets directly supporting business team migration prioritization

PayPal — Customer Identity Platform (CIP)

2025 | Next.js, Node.js, Express, Redis, gRPC, K8s

End-to-end ownership: design, development, testing, security audit, and production release.

  • Built project structure, page routing, BFF API, Redis caching, and K8s production deployment configuration
  • Implemented privacy policy management and user consent tracking meeting PIPL compliance requirements

Quantex — Disney AI Digital-Human Customer Service

2024 | React, Next.js, Three.js, react-three-fiber, Azure AI
  • Integrated 3D avatar model: Web rendering, Azure ASR / TTS voice sync, and lip-sync; initial integration completed in 1 month

Trip.com — International Content Platform

2020–2024 | React, Next.js, Node.js, Express, SSR, Redis, MySQL

Project URL: https://www.trip.com/blog

  • Built the department's first Node.js SSR content platform; drove team migration from .NET stack
  • Long-term ownership of Trip.com Blog / Destinations multilingual content channels; optimized Core Web Vitals and SEO

Open Source

Ongoing personal experiments in developer tooling, CLI engineering, and platform standardization.

Developer Tools / CLI: lobster, nsgm — OpenAI Function Calling-compatible tool registry + REST API (standardized tool invocation for AI Agents); Next.js + GraphQL + MySQL full-stack code generation scaffold (94+ commits, actively maintained)

Component Registry / Docs: shadcn-registry — self-hosted shadcn/ui component registry + Storybook 9 documentation site; demonstrates platform engineering thinking for internal component distribution and standardization


Education

Nanjing University of Information Science & Technology | B.Sc. in Information and Computing Science | 2001–2005

Target Role

Desired Position: Platform Engineer / Developer Productivity Engineer / DevOps / Tooling Engineer
Location: Shanghai preferred; open to remote
Availability: Immediately
Target Industries: Developer platforms, internal tooling, AI toolchains, FinTech infrastructure, DevX engineering
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