The framing of tests-as-source-code resonates, but I think it extends further than testing specifically. From my experience building with AI coding tools, I spend increasingly more time reviewing and validating code than writing it. You end up acting like an engineering manager running a team of junior devs: scoping tasks tightly, reviewing output critically, deciding whether what came back meets the requirement. Tests are one expression of that, but so is code review - they're both forms of validation. The broader shift is that the developer's primary output is becoming judgment about correctness rather than the code itself.