Full Stack Engineer

AI-First Senior Software Engineer

Ukraine, Kyiv · On-Site · Full-Time

Company: Orbox Group - new AI-native product for the oil & petroleum business in Ukraine

Location: Ukraine, Kyiv - on-site, office in the city centre

Employment: Full-time, permanent

Seniority: Senior

Reports to: Tech Lead

Works with: Business Analyst, UI/UX Designer, QA Engineer, business owners & operations team

Mobilization reservation: Full reservation (deferment) from mobilization for male employees

Languages: English - Advanced (B2-C1); Ukrainian - fluent

The role

This is the role that turns a real offline business into production software - by leading AI agents, not by typing every line yourself.

This is a hands-on senior engineering role. Most of our code is written by AI coding agents against machine-readable specs. That makes senior engineering judgment more valuable, not less: agents write fast, but still pick wrong abstractions, miss edge cases, get money and inventory maths wrong and ship code that passes its own tests and breaks in production. You are the engineer who designs the system, sets the guardrails and owns what gets merged.

We operate in a fast-moving startup environment where speed and precision both matter. You must be opinionated about which engineering tasks AI does well today (boilerplate, refactors, tests, migrations, docs), which it does not (architecture, security boundaries, trade-off calls, debugging subtle production issues) - and how to combine both deliberately.

What you will own & do

AI-First Engineering

• Daily, deep, native use of AI coding agents for implementation from specs, refactoring, test writing, code review, debugging and documentation.

• Treat agents like a team you lead: clear specs in, reviewed code out - you own the context, rules files, guardrails and the review bar.

 Set up the agentic delivery pipeline for the new product from day one: repo conventions, agent instructions, MCP tooling and CI checks that keep agent output safe to merge.

• Contribute to internal evals from the engineering side: define what good” looks like for AI-generated code and for the product's user-facing AI features.

Product Engineering

• Own the architecture from zero: service boundaries, domain and data model, APIs, environments - built for a real operational business with multiple sites and roles.

• Own features end to end: from spec & acceptance criteria to design, implementation, tests, deployment and monitoring on prod.

• Build operational surfaces: dashboards, inventory and stock movements, orders, pricing, documents, approvals, reporting and back-office tooling - including mobile-friendly flows for people in the field.

Integrations & Data

• Integrate with the existing world: accounting and ERP systems, Excel and legacy data, banks and payment providers, fiscalization and regulatory reporting.

• Connect the physical side of the business where relevant.

• Plan and run data migration from spreadsheets and legacy tools - reliably, idempotently, with proper error handling and audit trails.

AI & LLM Systems

• Build production AI features: LLM agents, tool calling, RAG, document processing (waybills, invoices, contracts), reconciliation, forecasting and anomaly detection - with grounding, fallbacks and cost control.

• Engineer the non-deterministic layer: prompt versioning, structured outputs, guardrails against hallucinations and prompt injection, role-safe access to data.

• Instrument AI behaviour with tracing, logging and metrics - treat AI output as something to be measured, not trusted.

Engineering Quality & Ownership

 Own the merge bar: review agent and human PRs, enforce architecture, security and performance standards.

 Write automated tests and CI that make agent output safe to ship; partner with QA on test strategy and release readiness.

• Feed spec & story defects back upstream: when the work item is wrong or ambiguous, it gets fixed at the spec layer with the Business Analyst, not hacked around in code.

• Shape the engineering practice for the product: conventions, environments, observability, incident handling - lightweight enough for startup speed, rigorous enough to trust.

What we are looking for

Must have

 4+ years of hands-on software engineering on production web products, with senior-level ownership of a system or major product area.

 Strong full-stack skills: modern backend (TypeScript / Node.js or Python), modern frontend (React / Next.js or similar) and relational databases (PostgreSQL or similar).

• Daily, deep, native use of AI coding tools (Claude Code, Cursor etc.) in your engineering workflow. You have a real, opinionated workflow built around them and can defend your choices.

• Hands-on experience building LLM-based features: agents, tool calling, RAG, structured outputs - shipped to production, not just demos.

• Solid system design for operational B2B software: transactional data, inventory and money flows, role-based access, API design, async processing, third-party integrations.

• Critical code review skills: you read AI-generated code with suspicion and catch what agents miss - security holes, data leaks, wrong abstractions, hidden complexity.

• Cloud & DevOps fluency: Docker, CI/CD, at least one major cloud (AWS / GCP / Azure), logging and monitoring.

• 0 → 1 mindset: comfortable starting a product from an empty repo, working directly with founders, business owners and product, shipping fast without losing rigor.

• Strong written and verbal communication in English and Ukrainian - including specs, PR descriptions, technical discussions and talking to the people who run the business.

Strong advantage (Nice to have)

• Experience integrating with BAS / 1C, Ukrainian banks and payment providers, fiscalization or tax / excise reporting.

• Document processing (OCR, extraction), forecasting or anomaly detection in production.

• Experience with LLM evals and observability (Langfuse, LangSmith or similar) and vector databases.

Why this role

You will own a new AI-native/AI-first engineering from an empty repo and prove that an AI-first delivery machine can transform a traditional industry, not just a startup niche.

• Genuine engineering ownership - you design the system from zero and hold the merge bar.

• Full reservation from mobilization for male employees.

 A real business as your first customer - live operations, real users, real volumes and money.

• Clear growth trajectory - Tech Lead / Engineering Lead for this product line.

• Direct access to founders and Head of Delivery & Product.

• AI-first by default.

• Great office in the centre of Kyiv.