A few weeks ago I published a piece called "AI Agents Are Great at 80% of Our Code. The Other 20% Is Why We Still Need Seniors."
It got 25 reactions and 34 comments. Several of those comments asked the same question in different words:
"How do you actually measure that 20% when you're hiring?"
Fair question. I dodged it in the first article because I didn't have a clean answer yet. Now I do. Or at least, we have a process that's working better than anything we tried before.
This is that answer.






