Engineering
Seniority is depth, not tools
Most senior engineers I have interviewed would fail a simple fundamentals test. Not because they are weak. Because the industry spent a decade paying for framework fluency instead of depth.
I keep meeting people with eight years on the résumé who cannot explain what happens when you type a URL and press enter. They have never read an EXPLAIN plan. The event loop is magic. The garbage collector is folklore. They can make the framework work. They cannot say why it works.
That gap is invisible in a good week. It shows up the day the framework does not save you. When production is down, nobody opens the React docs to find out why the database locked. You need the layer underneath. That layer does not get memorized the night before.
What seniority actually is
Real seniority is not how many tools you can name. It is how far down you understand the few things that still matter when the logo on the box changes:
- Networks. Packets, latency, DNS, TLS, what “the request failed” actually means.
- Databases. Indexes, locks, isolation, why a query that looks cheap is not.
- Memory. What you allocated, who frees it, why the box ran out of RAM at 3 a.m.
- Concurrency. Races, pools, backpressure. The bugs that only appear under load.
Tools rotate every two years. Fundamentals last the whole career.
The test I actually use
I do not need a whiteboard theater. I ask you to take the system we are looking at and remove the framework from the middle. Can you still tell me the path of a request? Where state lives? What fails first when traffic doubles?
If the answer is “I would check the docs,” that is fine for a junior. For a senior it is a tell. Seniors have already burned themselves on that path. They can sketch it from scars.
What to do with this
Pick one production incident from the last year. Write the timeline without naming a library. If you cannot, that is the study plan. Not another course on the new UI kit. The boring layer: TCP, SQL, memory, locks.
Would you still understand your system if they took the framework out?