This article hits very close to what I have come up with myself and its good to see others thinking the same lines.

  Core modules: Coded by myself, AI reviews and AI to discover/learn.
  Stuff I don't care about Craft: API layer, CLI layer, Smoke tests, Integ tests - Dial AI heavy, and lighter human reviews accordingly
Obviously takes a lot of patience and very easy to sin, but on good days, its doable.

Tests not being core seems suspect

Unit tests are core. Of course depending on project size things change. I'm talking about just myself managing a large project gets difficult to do everything