Refactoring
Restructuring existing code to be cleaner and easier to change, while what it does for users stays the same.
What it tells you about a developer
Habitual refactorers leave code simpler than they found it and keep whole codebases healthy over years. The trait compounds, and counting features alone misses it entirely.
Refactoring is maintenance of the codebase itself: same external behavior, better internal structure. It produces no visible feature, so it is chronically underinvested and often read as wasted time from outside engineering. It is the main way technical debt gets repaid.