Staff Engineer, Harness Engineering

- 8+ years building software, including Senior+ scope at a high-growth company (8-12 years total, 3+ at Senior+).

- You've built or owned an agent harness at an AI-substrate company (or a strong open-source equivalent).

- You think in tool design, not just prompt design - the prompt is the last 5%, the tool surface is the work - and you can talk trade-offs between agent loops you've used and when each one wins.

- You've shipped sandbox infrastructure at scale (Firecracker, gVisor, or comparable isolation).

- You write code with AI daily and have strong opinions about which harness behaviors matter and which are theater.

- Strong written communication (RFCs, API contracts, integration guides).

- Bonus: open-source agent/harness contributions; sandbox/isolation depth; foundation-model partner or early-access experience.

On-site in San Francisco, in person, long days, high standards. You own the layer every other agent team builds against, so the leverage is enormous and so is the scrutiny - a harness decision you make shows up in every pod's velocity. A rebuild this large doesn't happen part-time or by committee.

The right person wants that ownership and that pace.

- Compensation (OTE): $253,000-$308,000 cash (base + target performance bonus), plus competitive equity.

- Location: San Francisco, in-office. Based here or willing to relocate.

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Benefits: Uber commuter benefits; breakfast, lunch, and dinner provided; snacks and coffee stocked; free gym membership; health, dental, and vision.

- Process: Founder call (15 min) → CTO deep-dive (60 min, harness architecture) → Super Day on-site → founder + CTO offer. No committee. Best offer, first.

To apply: If you've built a harness other engineers couldn't live without - send your resume, the harness, and tell us about a model-routing or sandbox decision you'd defend in five years.