Turbopuffer's interview question: 2 to 4 levels below the abstraction
Agents now write the first level of code. What to test in an engineering interview instead: how far down someone goes when it breaks.
- Can use an ORM.
- Can write good SQL.
- Understands how indexes work.
- Can tell you roughly how the data is laid out on disk.
That's Simon Eskildsen's grid, at Turbopuffer. The first thing he looks for in an interview, in his words: "whether someone has a history of understanding 2-4 levels below the abstractions they're working with."
He wrote it in 2024. I think it matters even more in 2026.
Because today, the first level is written by the agent. The ORM, the query, the component: Claude or Codex produce them very well.
Vlad Mihalcea said it this week: most of the time, Opus 5.5 proposes the solution he would have written. And now and then, design choices that would break in production.
Only someone who understands what lies underneath catches those mistakes.
For hiring, it changes the question. Not "can they use the tool?" Everyone can. Rather: "how far down do they go when it breaks?"
And that rarely shows on a CV. It shows in what the person built when they had to go down a level.
