Tweet by 0xblacklight

June 10, 2026

I interviewed close to two dozen people this week and something I heard a lot of is "I don't think about the code too much but I think a lot about system design and architecture" I don't think that's quite right, and here's why: before you ever get to system design you should think about program design system design is important! it matters a lot for scalability. but if you don't think about your type system and if you don't carefully design your seams and figure out how to make your code testable (you should probably use dependency injection btw) and if you don't think about where state lives and how it's managed and if you don't think about control flow and where abstractions should and should not exist your code is going to be an unmaintainable, poorly-factored mess of bad types and spaghetti code and even minor changes will turn into shotgun surgery and MASSIVE diffs I have seen it done I have even done it myself and it has never ended well "GPT-7 will fix it" does not help you when there's an incident at 3am that the agents can't debug and now you can't debug it either and now you have to unwind months of bad code I also have never heard "I don't look at the code, just at the system design" said by someone who is actually good at system design program design and system design are more closely coupled than people think this was a very strong (negative) predictor of how someone would do on the system design part of the interview make of this what you will

Author
0xblacklight
Date
June 10, 2026
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