Staff ML Engineer — RL & Production Systems

People In AI; San Francisco (CA); Hybrid; USD 270,000 - 280,000; Full time

Job summary

People In AI in San Francisco is seeking a Staff-level Machine Learning Engineer who blends deep reinforcement learning with production software engineering to shape experiments, model improvements, and ML infrastructure.

You will work between research and production, set technical direction, lead other engineers, and design systems for large-scale training and evaluation while remaining hands-on.

Qualifications

• Strong hands-on ML engineering experience and production mindset.
• Experience with model post-training or fine-tuning.
• Experience with RL or preference-optimization approaches such as GRPO, PPO, DPO, or similar.

Responsibilities

• Design and build reinforcement learning environments for agentic tasks.
• Develop task definitions, tool interfaces, reward structures, state management, and evaluation logic.
• Build post-training and fine-tuning pipelines across supervised fine-tuning and reinforcement learning.
• Develop verifiers, graders, rubrics, and evaluation systems for complex model behavior.
• Run and diagnose model-training experiments and ensure data and reward quality.

Skills

Hands-on ML engineering

Python

ML infra / distributed systems

System design

Technical leadership

Staff-level influence

Technical communication

Tools

Reinforcement Learning frameworks

Model evaluation tools

Job description

People In AI in San Francisco is seeking a Staff-level Machine Learning Engineer who blends deep reinforcement learning with production software engineering to shape experiments, model improvements, and ML infrastructure.

You will work between research and production, set technical direction, lead other engineers, and design systems for large-scale training and evaluation while remaining hands-on.