Matheus Lima argues that the standard senior engineer checklist — architecture, communication, ownership, leadership — misses the one core skill that actually separates senior+ engineers from everyone else: reducing ambiguity. A mid-level engineer can crush a well-defined problem with a clear spec and reasonable constraints. The gap appears the moment the problem is fuzzy — “improve performance,” “fix the onboarding flow,” “think about scaling.”
- Senior engineers ask questions nobody else thought to ask, separate signal from noise, and decide what to do now versus what to punt
- They derisk projects: turning “I don’t even know what this is” into “two small projects and one thing to cut”
- The clarifying work is invisible — when done well the project just goes smoothly, but someone did the hard work upfront
- Four questions seniors ask: (1) What problem are we actually solving? (2) Who is the user and what’s painful? (3) What assumptions might be wrong? (4) What’s the downside if we’re wrong?
- Most companies hire for this wrong — job descriptions list tech and years, interviews test LeetCode, neither measures ability to turn vague requirements into shippable plans
The author’s test for whether you’re operating at a senior level: what do you do when someone hands you something abstract? If you spend time upfront making it concrete enough for your team to execute with confidence, you’re already there. If not, the good news is this isn’t talent — it’s practice, starting with the next vague ticket assigned to you.