Comment by ali_mouiz

Spec-first was the unlock for me too. The agent drifts badly without it. Your point about defensive code is spot on, happy path works fine, but retry logic, edge cases, error handling all needed manual work in my experience too. The 80/20 observation is real. Functionality is fast, making it actually trustworthy takes most of the time.

I also added tons of unit-test, it helped ai agent to detect regression while producing code.