Senior Software Engineer, Open Harness Engineering

What you'll do

• Define and evolve technical approaches for evaluating and improving open agent harnesses across various frameworks and models.
• Build and operate scalable, reproducible evaluation systems including CI, sandboxed execution, and trace capture.
• Diagnose agent failures by analyzing traces, logs, tool results, and benchmark artifacts to identify root causes.
• Design controlled experiments and promotion criteria to distinguish genuine improvements from noise or model-specific gains.
• Ship harness and runtime improvements, including upstream open-source contributions, detectors, and regression tests.
• Develop reusable runtime, trace, and evaluation capabilities based on recurring optimization needs from partner teams.

What we're looking for

• Bachelor’s or Master’s degree in Computer Science, Artificial Intelligence, Applied Math, or a related field, or equivalent experience.
• 8+ years of hands-on software engineering experience with technical ownership of production systems and architecture design leadership.
• Expert Python skills and working proficiency in Rust, Go, C++, or TypeScript.
• Experience building or extending LLM agents, coding agents, tool-use loops, model-provider integrations, developer tools, or evaluation infrastructure.
• Solid understanding of asynchronous execution, subprocesses, containers, sandboxing, networking, and distributed compute.
• Experience crafting reproducible experiments, benchmark methodology, performance investigations, regression gates, or reliability analysis under nondeterministic conditions.
• Proven track record of shipping and maintaining open-source or developer-facing software with sound testing, API development, and documentation.
• Experience with trace-analysis and observability systems such as OpenTelemetry, OpenInference, or structured event pipelines.