答辩：自研还是买
「这个我们自己能写」——能写不等于该写。
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.
三条判据，有先后顺序：这件事是不是你们的核心差异化（客户会不会因为这一块做得好而选你们）；三年一共花多少（自研的大头不在开发，在维护、值班、升级和机会成本）；将来换得掉吗。
第二幕全程逼数字，其中「谁值班」「谁跟升级」「这些人不做这个会去做什么」这三项最常答不上来 —— 而它们恰恰是自研真正的成本。
还有一个多数提案里没有的选项：开源自建的成本结构和买完全不同，只比较「自研 vs 买」说明功课没做完。
What this one tests
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
The more specific the prompt, the sharper the grading: each specific one carries the root-cause checklist for that kind of situation, and the generic group is the fallback when none of them fits. The system design set grades you on "a benefit with no cost attached means you memorised it"; here the line is different: if you can't give a specific, it's empty.
How to start
- Pick one, open it, copy the prompt.
- Paste it into a brand-new conversation.
- Say in a sentence or two which thing you're going to talk about, then wait for its questions — unlike the system design set, where you say nothing after pasting.
Three commands you can call out at any time
跳过move to the next scene now换一个start over with a different project, outage or experience复盘jump to the wrap-up and print the review card
Three traps
- When it starts consoling you, point it back to the "don't praise me" rule — the two retrospectives are the likeliest to summon a model's soothing persona, which turns the whole thing into emotional support rather than a retrospective.
- Cut it off when it tries to complete your answer for you. You say "I don't remember", it offers "probably because the schedule was tight" — and that sentence is no longer your memory.
- Before pasting a CV or a design doc, strip out phone numbers, email addresses and anything your company wouldn't want leaving the building.
Got a proposal to pitch? Start with defending it. Just finished a project or lived through an outage? Do those retrospectives while you still remember. Job hunting? Audit the CV first, then take the lines that survived into the behavioural drill.
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