Сергій

[open contact info](look above in the "contact info" section)
Serhii Diachenko github.com/sgdiachenko
Ukraine (Remote) [open contact info](look above in the "contact info" section)

SUMMARY

Senior Frontend / Full Stack Engineer with 11+ years in development, including 9+ on LiveNX, an enterprise network
observability and analytics platform. Deep expertise in Angular/TypeScript, frontend architecture and system design, with
hands-on React, Node.js and NestJS experience.

Owned data-intensive frontend features from requirements to release and maintenance: analytics dashboards, complex
AG Grid tables, D3.js/Highcharts visualizations and asynchronous workflows with RxJS/NgRx. Designed feature
architecture and state boundaries, optimized rendering and application loading, and contributed to AngularJS-to-Angular
modernization. Led enterprise redesigns, establishing reusable components and shared styling for subsequent changes;
supported engineering quality through tests, code reviews and mentoring.

Build AI harnesses and Spec-Driven Development (SDD) workflows in independent projects. Implemented agent
orchestration, MCP integration, PR-review evaluations and execution/cost analytics. Can help teams make AI-assisted
development repeatable and verifiable: connect requirements to code and test evidence, evaluate agent changes, and
share reusable skills and workflows across repositories.

SKILLS

Core Technologies: Angular, TypeScript, JavaScript, React, Data Visualisation: AG Grid, D3.js, Highcharts, KeyLines,
RxJS, NgRx, NgRx Component Store, Angular Signals, Leaflet.js, Data-Intensive Tables, Interactive Dashboards,
SignalStore, Signal Forms, AngularJS, Gatsby Real-Time Data Visualization

Backend & APIs: Node.js, NestJS, Express.js, REST APIs, AI-assisted / Agentic Engineering: AI Harness
API Integration, WebSockets, PostgreSQL, MongoDB, Development, Spec-Driven Development (SDD),
Mongoose, Redis, RabbitMQ, BullMQ, OpenAPI/Swagger, Agent/Subagent Orchestration, Context Engineering, Model
JWT Authentication, Resource-Level Authorization, Context Protocol (MCP) Server Integration, Agent Evals, AI
Role-Based Access Control (RBAC) - Frontend Integration Code Review & Verification, Workflow Observability & Cost
Analysis; Claude Code, Codex, Cursor, GitHub Copilot
Frontend Architecture: Frontend System Design, Nx
Monorepo, Component-Based and Feature-Based Testing & Tooling: Test Strategy, Unit Testing, API
Architecture, Reactive State Management, Reactive Data Integration Testing, E2E Testing, Jest, Vitest, Playwright,
Flows, Dependency Boundaries, Standalone Components Selenium, Karma

Software Engineering: SOLID, Object-Oriented Software Delivery: CI/CD, Jenkins, GitHub Actions, Docker,
Programming (OOP), Domain-Driven Design (DDD), Clean Docker Compose, Build Automation, Release Workflows
Architecture, Legacy Refactoring, Design Systems,
Performance Engineering: Rendering Optimization, Bundle
Component Libraries, Storybook, Maintainable CSS
Analysis & Optimization, Caching Strategies, Lazy Loading,
Architecture, Technical Design
API Request Optimization, Asynchronous Data Processing
Frontend Development: HTML5, SCSS/SASS, Angular
Collaboration: Git, Git Workflows, Agile/Scrum, Jira,
Material, PrimeNG, Tailwind CSS, Bootstrap, shadcn/ui,
Confluence, Cross-Functional Collaboration, Code Reviews,
GSAP, Responsive Design, Cross-Browser Compatibility
Mentoring

WORK EXPERIENCE

Software Engineer, GBSFO / LiveNX, SaaS Feb 2016 - Jul 2025
Worked on LiveNX, an enterprise network observability and analytics platform for understanding and troubleshooting
complex networks. LiveAction serves organizations including IBM, Salesforce and Ford, as well as the public sector.

● Owned frontend features from requirements through delivery and maintenance. Translated product requirements
into technical designs, collaborated with backend engineers on API integration, and carried features through
implementation, testing and release, coordinating technical decisions with product, design and QA.
● Designed frontend architecture to address growing complexity and inconsistent data handling. Applied SOLID
principles to component and service design, organized functionality into feature modules with explicit state
boundaries using NgRx and NgRx Component Store, and standardized container/presentational patterns and reactive
data flows, separating UI composition, state management and API orchestration.
● Built data-intensive analytics dashboards and interactive visualizations. Implemented complex AG Grid tables and
D3.js/Highcharts charts, integrating asynchronous data transformations and state management to support network
analysis through coordinated tables, visualizations and user workflows.
● Optimized performance in data-heavy frontend workflows. Addressed rendering and API-interaction bottlenecks using
RxJS and OnPush change detection, and applied bundle-size optimization and lazy loading to improve application
loading and responsiveness.
● Implemented Node.js Backend-for-Frontend (BFF) functionality for dashboard widgets and tab management,
integrating backend endpoints exposed through an API Gateway with Angular workflows.
● Led enterprise redesigns and established reusable UI foundations. Addressed duplicated components and scattered
styling by collaborating with designers on reusable Angular and React components, Storybook documentation and
maintainable CSS with shared tokens, variables, mixins and helpers, establishing common update points for
subsequent visual changes.
● Established consistent error handling for complex frontend workflows. Implemented centralized handling, HTTP
interceptors and graceful degradation to address failures in data-intensive interfaces and provide consistent error
behavior across affected workflows.
● Built a React/Gatsby documentation website covering the LiveAction product portfolio. Developed and maintained
product documentation interfaces and React component showcases, providing shared references for product
guidance and reusable UI.
● Modernized legacy interfaces while preserving existing product workflows. Contributed to AngularJS-to-Angular
migration and the migration of complex React UI modules to Angular, aligning migrated functionality with shared
component, state-management and data-flow patterns.
● Implemented and maintained Jest unit tests for LiveNX application behavior, adding regression checks as features
and legacy code evolved.
● Integrated role-based access control (RBAC) into application navigation. Implemented page-access checks using
role-derived permissions, aligning available frontend routes with the product’s authorization model.
● Contributed to engineering standards through architecture discussions, code reviews and mentoring. Promoted
shared design patterns, maintainable code structure and reusable UI practices across the frontend team.

Front-End Web Developer, HTML Experts Mar 2015 - Feb 2016

● Delivered animation-rich marketing websites and landing pages targeting Awwwards-level visual quality.
Implemented detailed visual designs and complex motion using JavaScript and GSAP, balancing animation behavior
with rendering performance and responsive layouts.
● Built reusable templates and styling patterns. Used Pug, Handlebars and SCSS to structure recurring UI elements and
shared styles, supporting consistent implementation and maintainable updates across pages.
● Resolved cross-browser and device-specific UI issues. Refined layout, interaction and animation behavior to preserve
a consistent experience across supported browsers and screen sizes.

SELECTED ENGINEERING PROJECTS

DevDigest & AI engineering harness 2026

React-based PR-review application and agentic development workflows

● Built an agentic engineering harness with specialized agents for research, planning, implementation and independent
verification, supported by reusable skills and controlled tool access.
● Implemented Spec-Driven Development (SDD) connecting requirements, acceptance criteria, implementation and
verification evidence.
● Integrated PR reviews with coding agents via MCP, including a local MCP server and structured AI-generated PR
briefs with risk analysis.
● Developed evaluation and observability tooling with deterministic review scoring, execution statistics, token usage
and cost analysis.

DevDigest repository: https://github.com/sgdiachenko/dev-digest

AI Marketplace 2026

● Reusable AI skills, agents and engineering workflows
● Built a reusable plugin ecosystem for distributing AI agents, skills and workflows across projects, with dependency
and version validation.
● Automated quality and release processes through CI checks, behavioral evaluations, release automation, installation
testing and rollback support.
● Created a searchable, localized plugin catalog generated from metadata for easier tooling discovery and adoption.

AI Marketplace repository: https://github.com/sgdiachenko/gm-ai-marketplace

LANGUAGE

● English: B2+ (Upper-Intermediate), extensive experience collaborating with international product and engineering
teams, including several technical calls a week with the US-based product team and ongoing written communication
with developers and QA engineers.
● Ukrainian: Native

EDUCATION

O.S. Popov Odessa National Academy of Telecommunications 2007 - 2013

Master of Engineering | Computer Systems Networking and Telecommunications

PROFESSIONAL DEVELOPMENT

AI Agentic Engineering (Neoversity) 2026

Completed a five-week course covering AI harnesses, agent/subagent workflows, spec-driven development, MCP
integrations, evaluations, reusable skills/plugins and workflow cost analysis. Applied these practices in the independent
projects described above.