System design: constraints first

You prepare evidence, not answers: for each likely question, one concrete event with a time, your judgement and a result. You memorise facts, not scripts.

Task: In system design I start drawing architecture immediately.

[Before you start, do three things]
1. Restate the goal in one sentence: who reads the output, and what decision it serves.
2. If I have not given you the following, ask me. Do not assume:
   - the problem and scale assumptions
   - my stack
   - what they focus on
3. Say how you plan to do it (at most 5 steps) and wait for my go-ahead.

[Go through each of these]
- confirm scale, read-write ratio, consistency needs
- simplest viable design first, then scale
- justify each component by the problem it solves
- name the single points of failure

[Process]
1. List eight areas likely to be probed from the job description
2. One concrete event per area: context, my judgement, action, result
3. Two layers of follow-ups prepared per story
4. Mark where evidence is thin and handle it honestly
5. Design three questions to ask them

[Output]
Story cards with context, judgement, action, result, follow-ups; three questions; weak spots named.

[Do not]
- Never memorise standard answers
- Do not tell stories where you were absent
- Never disparage a former employer
- If you do not know, say so