Advanced Reinforcement Learning Interview Questions, issue 21, Feb 16, 2026
The Happy Path Trap
Machine Learning Engineer interview at OpenAI, and the interviewer asks:
“We are building an RL agent to grade student-coded video games (like Breakout). How do you design the reward function to catch the most bugs?”
When reward design mirrors end-user success metrics, the policy converges to safe trajectories and systematically under-explores the brittle edges of the simulation.
The full answer, with the mechanism and the arithmetic, is for paid subscribers on Substack.