Software Engineer, RL Data — Cursor (Anysphere)

Our mission is to automate coding. The first step in our journey is to build the best tool for professional programmers, using a combination of inventive research, design, and engineering. Our organization is very flat, and our team is small and talent dense. We particularly like people who are truth-seeking, passionate, and creative. We enjoy spirited debate, crazy ideas, and shipping code.

Software Engineer, Reinforcement learning

• SpaceXAI is building the future of coding. We train frontier coding agents and scale RL on real user data to make them increasingly effective.

About the role

• As a Software Engineer on the RL Data team at SpaceXAI, you'll create the tasks, rewards, and environments that train our coding agents. The team owns the data that goes into training: what the model is asked to do, how we score it, and the setups it learns in.

What you’ll do

• Designing a task set that teaches a specific agent capability, then iterating on it from traces and evals until the model actually gets better.

• Reading a pile of agent traces, finding a failure mode or a surprising behavior, and building a system that surfaces more of the same.

• Turning a one-off recipe into something other teams can reuse: better rewards, cleaner environments, tighter data quality.

• Partnering with research on whether a dataset is actually teaching the thing we think it is.

You may be a fit if

• You write careful, fast code and have strong software engineering fundamentals.

• You like setting tasks: breaking a fuzzy capability into something concrete you can measure.

• You have an infra, data, or distributed systems background. RL experience is a plus, not a requirement.

• You enjoy looking at messy real-world agent behavior and turning it into a dataset or a tool.