Mid-Senior Agent Harness Engineer

Our Client is building the AI coworker of the future.

Living directly inside Slack and Microsoft Teams the platform connects with thousands of business tools and executes real work across finance operations marketing engineering and customer workflows. The vision is simple but ambitious: replace a significant portion of todays fragmented SaaS stack with a single AI-powered teammate.

As the company scales rapidly they are looking for exceptional engineers to help build the core systems powering the next generation of autonomous AI agents.

• Location: Warsaw Poland (On-site)
• Employment Type: Full-Time
• Level: Mid-Senior
• Compensation: Competitive Salary Meaningful Equity
• Work Authorization: Valid Work-Permit for Poland

• Design and improve agent runtimes
• Build memory and context management systems
• Develop tool orchestration frameworks
• Implement verification loops and self-checking mechanisms
• Improve reliability and execution accuracy

• Build integrations with customer-facing platforms and APIs
• Implement OAuth webhooks schema mapping and error handling
• Connect and maintain integrations across platforms such as: Slack Microsoft Teams Salesforce HubSpot Stripe Shopify QuickBooks Notion

• Manage containerized workloads and runtime environments
• Improve scalability and operational efficiency
• Optimize infrastructure costs and performance
• Support systems handling hundreds of thousands of daily tool calls

• Ship customer-facing features rapidly
• Work across backend frontend integrations and deployment systems
• Collaborate directly with founders
• Own technical surfaces end-to-end

• Experience building or significantly modifying AI agents
• Strong Python development skills
• Strong TypeScript development skills
• Experience with agent architectures and orchestration systems
• Experience shipping production software rapidly
• Strong systems thinking and engineering judgment
• Ability to make practical technical trade-offs
• Experience with APIs integrations and distributed systems
• Deep familiarity with AI-assisted development workflows

• Built AI agents running in production environments
• Experience creating custom skills CLIs MCP servers or internal tooling
• Open-source contributions within AI ecosystems
• Experience building Slack or Teams applications
• Infrastructure and DevOps experience
• Experience managing high-scale systems
• Previous startup or founder experience
• Strong interest in AI systems evaluations and emerging models

• Competitive salary package
• Meaningful early-stage equity
• Direct collaboration with founders
• High ownership and autonomy
• Immediate product impact
• Fast feedback loops from real users
• Opportunity to work on cutting-edge AI systems
• A high-trust low-process environment focused on shipping

If you have already built AI agents enjoy shipping quickly and want to help define the future of AI coworkers wed love to hear from you...