Founding AI Agent Harness Engineer (Remote)

Bolder Apps; United States; Remote; USD 140,000 - 210,000; Full time

Job summary

Partner Company is building an AI coworker that lives inside a team’s tools and gets work done. We’re hiring a senior Founding Harness Engineer to design the layer that decides when to act, which tools to use, and how to finish long tasks reliably.

You’ll join a founder-led team, working remotely from LATAM or Eastern Europe with solid overlap to US Pacific time. The role starts as a contract with a path to full-time as it proves itself.

Qualifications

• Experience shipping tool-using agents in production
• Strong backend and async systems knowledge
• Ability to explain tradeoffs to a founder or user

Responsibilities

• Build the agent runtime: context, tool choice, approvals, and when to act
• Tune and maintain system prompts; avoid noise to the team
• Own eval and regression harness; tests for prompt changes as code
• Ensure long tasks survive interruptions, retries, and flaky APIs
• Implement guardrails: approval gates and data separation
• Collaborate with founder and early users to ship observed behavior

Skills

Python

TypeScript

LLM tooling

Backend development

Tools

Braintrust

Langfuse

LangSmith

Job description

Partner Company is building an AI coworker that lives inside a team’s tools and gets work done. We’re hiring a senior Founding Harness Engineer to design the layer that decides when to act, which tools to use, and how to finish long tasks reliably.

You’ll join a founder-led team, working remotely from LATAM or Eastern Europe with solid overlap to US Pacific time. The role starts as a contract with a path to full-time as it proves itself.