Software Engineer, Model Lifecycle and Signals
New York · San Francisco · Full-time · Onsite · Posted Oct 15, 2026
At a glance
- Employment
- Full-time
- Workplace
- Onsite
- Location
- New York · San Francisco
About the role
- As a Software Engineer on the Model Lifecycle and Signals team at SpaceXAI, you'll own the bridge between frontier models and every user facingCursor product, used at a scale few teams ever see.
- You'll decide when we use which model, spot where models go off track and build the guardrails to keep them on it, and shape what the next generation of models should learn.
- This role sits at the intersection of infrastructure, data, and product.
Responsibilities
- Get new frontier models into users' hands the day they're ready, and retire old ones without anyone noticing.
- Evaluate internal and external preview models before launch and give meaningful feedback to the teams building them.
- Build Cursor Router to decide which model handles each request, balancing quality, speed, and cost at massive scale.
- Build the eyes and ears of the product, and the experimentation platform that puts them to work: signals that show where each model shines, where it goes off track, and what 'better' actually means.
Requirements
- You're an exceptional engineer with a track record of shipping production systems people rely on.
- You've built and operated evaluation, measurement, or model serving systems, such as AI evals, experimentation, ranking/relevance, or routers.
- You're fluent with data and can collaborate effectively with data scientists and researchers.
- You have strong taste and real curiosity about model and agent behavior.
