K: Okay—here’s how we’ll run this. I’ll start with a quick overview (about 5 minutes). Then we’ll do a fast pass on goals and level-setting (around 2 minutes). After that, we’ll spend the bulk of the time on the system design portion (roughly 65 minutes). We’ll finish with some initial feedback and a short recap. Sound good?

Q: Yep, sounds good to me.

K: Great. For introductions, let’s keep it to about one to two minutes each. Since this is an interview context, share only what you’re comfortable sharing. Want to go first, or should I kick us off?

Q: You can start.

K: Sure. I’m [Name]. I’ve been working for about nine years, mostly in machine learning engineering at large tech companies. I previously worked at Amazon and Microsoft, and I’m currently at OpenAI. I’ve spent a lot of time on both sides of the table and have run many system design interviews, especially for senior candidates. That’s the quick version of me—how about you?

Q: Sure. I’m currently a senior software engineer. Right after graduation I started out doing mobile development for a bit. I began my U.S. career at Amazon, then later moved to Meta. At Meta, I shifted away from staying strictly in mobile and moved into a more general backend role. I don’t really bucket myself as “feature-only” or “ML-only”… over time I expanded into a broader backend / leadership role across the XXX platform and XXX stack.

(省略：一些关于“很期待加入 OpenAI ……”之类的表忠心…)

Level-wise, I’m probably around the E6–E7 range at Meta—roughly Staff to Senior Staff. And honestly, system design is the hardest part for me compared to DS&A, so I’m putting most of my prep time there.