第一个字节到达之前，来回跑了几趟
打开一个 2KB 的接口，网络上来回跑了几趟？
Copy the prompt, then pick a model. It plays the interviewer and asks you through it scene by scene instead of handing you the answer.
On a phone with the app installed, the system opens the app directly. Links cannot open external apps inside WeChat — open it in a browser first.
The copied text ends with the answer key the model grades you against. Don't read it yourself first — working it out on your own is the point.
它会让你一趟一趟数：DNS、TCP 握手、TLS 握手、请求响应。然后算一笔账 —— 那 2KB 数据本身在 100Mbps 上只要零点几毫秒，而那几趟可能是几百毫秒。
这一笔账算完，「网慢就加带宽」这个直觉会被彻底拆掉：跨太平洋的往返有光速下限，加钱也买不到。
顺带解释一条老建议的来源：为什么首屏关键资源要压在 14KB 以内。
What this one drills
This prompt in the repo (the answer key is at the end of that file — you'll see it)
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Notes from people who did this one
How to use this
This set teaches rather than interrogates: it guides you instead of pressing until you have nothing left to say. When you're stuck it first asks which layer you're stuck at (never heard of it / know it but not why / know why but can't apply it), then decides what to give. Only after guiding you twice on the same point will it spell it out — and then it asks you to say it back in your own words.
It will keep pushing you for numbers: answer "there's some overhead" or "it's faster" and it cuts you off. A conclusion you can't put a number on is a memorised one — that's exactly what this set drills.
How to start
- Pick one, open it, copy the prompt.
- Paste it into a brand-new conversation, say nothing, and wait for its first question.
- Expect to be asked for orders of magnitude: how many nanoseconds, how many microseconds, how many times slower. Saying you don't know is fine — it notes it and moves on.
Four commands you can call out at any time
跳过move to the next scene now换个说法explain this bit again from another angle直说吧spell the answer out, then make me say it back复盘jump to the wrap-up and print the review card
Three traps
- Don't read the answer key at the end first — that "how people get it wrong" section is the answer to every question it will ask.
- Don't reach for the jargon. Saying "that's a TLB miss" is easy; saying how much cheaper it is than a page fault is the part that counts.
- When it starts praising you, point it back to the "don't praise me" rule. Guiding is not coddling.
Want a feel for the numbers? Start with random reads and the first-byte one. For production debugging: malloc, TCP stalls, context switches. Writing concurrent code: reordering and false sharing.
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