Mid-Senior Agent Harness Engineer, Python, TypeScript

Cross Border Talents

Building core infrastructure for AI agents at a rapidly scaling company that integrates with major platforms. Seeking exceptional engineers to improve their AI-powered solutions.

Posted 6/13/2026full-timeRemote • 🇵🇱 PolandSeniorWebsite

Tech Stack

Tools & technologies

Distributed SystemsPythonTypeScript

About the role

Key responsibilities & impact

Build Agent Runtime Systems; Develop and improve agent runtimes
Design tool orchestration frameworks
Build memory and context management systems
Implement verification loops and agent self-checking mechanisms
Improve reliability and execution accuracy
Ship Integrations; Build integrations with business platforms and APIs
Implement OAuth, webhooks, schema mapping, and data synchronization
Create reliable workflows that operate on real customer data
Support integrations across platforms such as: Salesforce, HubSpot, Stripe, Shopify, QuickBooks, Notion, Microsoft Teams, Slack
Manage containerized workloads
Improve scalability and system reliability
Optimize infrastructure performance and operational costs
Support high-volume production workloads
Ship user-facing features directly into production
Collaborate directly with founders and product stakeholders
Own technical surfaces end-to-end

Requirements

What you’ll need

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 architectural decision-making abilities
Experience working with APIs, integrations, and distributed systems
Strong understanding of AI-assisted development workflows
Open-source contributions within AI ecosystems (preferred)
Experience with developer tooling and automation (preferred)
Experience creating custom agent workflows, MCP servers, or CLI tooling (preferred)
Infrastructure and DevOps experience (preferred)
Experience with Slack or Microsoft Teams applications (preferred)
Previous startup or founder experience (preferred)
Deep interest in AI systems, evaluation methodologies, and emerging models (preferred)

Benefits

Comp & perks

Competitive compensation package
Meaningful early-stage equity
Direct collaboration with founders
High ownership and autonomy
Opportunity to build core AI technology used by real customers
Fast product feedback cycles
Remote-first work environment within Poland
Exposure to cutting-edge AI systems and infrastructure

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills & Tools

PythonTypeScriptAI agentsorchestration systemsAPIsintegrationsdistributed systemsdeveloper toolingautomationMCP servers

Soft Skills

systems thinkingarchitectural decision-makingcollaborationreliability improvementexecution accuracyworkflow creationscalability improvementself-checking mechanismscustomer data managementproduction software shipping