Harness Engineer – AI Agents Platform

About the role

Leanpay is a Buy Now Pay Later (BNPL) company based in Serbia, with operations in Romania and Slovenia. It is expanding its IT team and is adding an AI team to make AI agents a reliable part of its lending platform, from requirements to production. The Harness Engineer designs and builds the software behind the AI delivery process, including guardrails, recovery loops and observability.

Key responsibilities

• Design and develop the software behind the AI delivery process: its stages, checks, integrations and workflow logic.
• Build guardrails, recovery loops and observability for AI agents so failures are visible, contained and cheap.
• Turn architecture, security and regulatory rules into automatic checks that cannot be skipped under pressure.
• Diagnose agent failure modes and fix their causes in the process, not only the symptoms.
• Build and maintain the mechanics that deliver knowledge to AI agents.
• Deliver a small share of product features to test the process on real work.
• Support delivery teams in adopting the AI delivery process, propose technical standards and share knowledge.

Required profile

• University degree with a technical orientation.
• 4+ years of software development, with hands-on experience in production software, system design and the full SDLC.
• Hands-on experience with AI agents and AI-assisted development.
• Knowledge of guardrails, recovery and observability for automated systems.
• Strong problem-solving skills and clear written communication in English.
• Plus: fintech or banking experience, and experience designing systems that other engineers build on.

Required skills

• Software development in Java, Python, TypeScript or a similar language.
• Software design, testing and code review practices.
• CI/CD pipelines and build tooling (Jenkins, Maven or Gradle).
• Docker, Kubernetes and cloud environments (Google Cloud or AWS), including logging and monitoring.
• AI coding agents (e.g. Claude Code) and their extension points (tools, hooks, MCP); AI agent orchestration frameworks are a plus.

What we offer

• A competitive package aligned with similar positions on the market.
• Opportunities for job advancement and career development.
• 25 days of annual vacation and 5 days of fully paid sick leave per year.
• Hybrid working model based in the Belgrade office, with lunch provided.
• Private medical insurance.
• A positive, flexible work environment.