Principal Backend Architect — Agent Harness & Training Infra

United States Digital Space LLC; San Francisco (CA); On-site; USD 180,000 - 260,000; Full time

Job summary

The company is seeking a Principal Software Engineer to lead the architecture and evolution of the Agent Harness Bridge, owning a critical interface between research and engineering for agentic coding infrastructure. You will guide system design, APIs, and operational patterns enabling researchers to run training workloads safely and efficiently.

Ideal candidates bring senior backend or infrastructure expertise, strong judgment, and the ability to drive cross‑team execution while delivering

Qualifications

• Experience in designing robust APIs and scalable systems.
• Strong grounding in software architecture and engineering fundamentals.
• Proficiency in Python; backend platform engineering experience preferred.
• Rust knowledge is a plus for performance-critical components.

Responsibilities

• Design, build, and evolve the bridge between the Codex harness and research training infrastructure.
• Own major integration surfaces end-to-end, from architecture and API design through rollout and maintenance.
• Build reliable, containerized execution systems that can scale for demanding training workloads.
• Partner with research, agent, infrastructure, and platform teams to support new training use cases and harness capabilities.
• Design clean, stable interfaces and workflows for highly technical internal users.
• Prevent one‑off workarounds from becoming long‑term debt by establishing durable abstractions and clear ownership.
• Raise the bar for correctness, reliability, operational rigor, and engineering judgment across a critical research‑facing system.

Skills

API design

Systems design

Python

Backend platform engineering

Rust

Job description

The company is seeking a Principal Software Engineer to lead the architecture and evolution of the Agent Harness Bridge, owning a critical interface between research and engineering for agentic coding infrastructure. You will guide system design, APIs, and operational patterns enabling researchers to run training workloads safely and efficiently.

Ideal candidates bring senior backend or infrastructure expertise, strong judgment, and the ability to drive cross‑team execution while delivering