# What interviews teach me about people (and my own company) · Mattia Ciuni

> What written technical work reveals that a conversation can hide, and why every interview has become an audit of my own company.

- URL: https://mattiaciuni.pages.dev/notes/what-interviews-teach-me-about-people-and-my-own-company
- Type: Note
- Published: 2026-09-21

## Full article

# What interviews teach me about people (and my own company)

I've been running interviews differently this month. Not the usual "tell me about yourself and your five-year plan." Every candidate gets a real technical task first, then a structured questionnaire with questions born from my own audit: how they'd fix an [idempotency race](/notes/idempotent-payments-for-ai-agents/), how they'd handle two concurrent payments against the same budget, what they validate at boot.

The questionnaire is written, not verbal. And that choice taught me more than I expected.

Same person, two formats: in a call, one candidate gave me shallow answers. In writing, with time to think, the same candidate handed me a floating-point analysis of 10.10 × 100, caught a race condition I had hidden in my own question, and mapped every possible shape of a double-charge incident before touching anything. The call undersold him. The text proved him.

That's now a principle in how I hire: measure people in the format where they think best. Voice-strong and write-strong are both valid engineers, but you'll only see it if you ask both ways.

The other thing interviews give me, which nobody talks about: my own questions get sharper with every candidate. Each answer shows me a gap in how I explain our architecture, or a new edge case I hadn't considered. I've redesigned parts of our onboarding and our docs from things candidates asked. The interview is not a filter. It's a mirror.

So yes, I'll keep interviewing. For the team, for the practice, for the mirror. If you're an engineer who does your best thinking in writing, my inbox is open. The first step is always the same: ship something real, then we talk.

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