Kacam.net

System design

通知与推送系统

多通道、有配额,还不能把同一条推两遍。

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.

这道题在这个站上有真实的对照物:「此刻」那条推送链路。

做完之后建议对着这个项目的 AGENTS.md 读一遍那一节,看你答的和真做出来的差在哪 —— 这种对照比多做一道题有用。

★★★☆☆ · about 35 min · Tests: 多通道抽象、模板与频次控制、第三方配额、重复推送、token 失效

Cross-cutting patterns this one leans on

Idempotency Rate limiting, shedding, breaking, degrading Message queues Third-party integrations Time and time zones Observability

Have you done this one?

Sign in to mark this one as practised — next time you come back you'll see when you did it.

Notes from people who did this one

Nobody has written yet. After you run it, say what came out of the conversation — which scene stumped you, which conclusion you changed afterwards.

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How to use this

How to start

  1. Pick a question, open it, copy the prompt.
  2. Paste it into a brand-new conversation — not one where you already discussed this question, or the model follows your old answers.
  3. Say nothing. Wait for its first question.

Four commands you can call out at any time

  • 跳过 move to the next scene now
  • 提示 give a direction, not the answer
  • 直说吧 spell this point out in full, then keep pressing on the trade-offs
  • 复盘 jump to the wrap-up and print the review card

Three traps

  • Don't do two questions in one conversation — context from the first makes the model prejudge your level.
  • Don't look up the answer the moment it asks. Being stuck for 30 seconds is itself useful information.
  • When it starts praising you, point it back to rule five — feeling validated crowds out noticing what you missed.

Suggested order: start with the cross-cutting drill as a parts test, use the short-link question to get used to the flow, then pick by the direction you interview for, and keep redoing the one about your own project.