Describe a situation where you partnered with product, engineering, design, or research to launch or evaluate an A/B test. What was your role in aligning the team on hypotheses, success metrics, and guardrails, and how did you handle experimentation pitfalls such as sample-ratio mismatch, novelty effects, peeking, interference, or underpowered results? Tell me how you navigated differing priorities across functions and what decision the team made in the end.