Boris has been very open about the 100% AI code writing rate and my own experience matches. If you have a typescript or common codebase, once you set your processes up correctly (you have tests / verification, you have a CLAUDE or AGENTS.md that you always add learnings to, you add skill files as you find repeatable tasks, you have automated code review), its not hard to achieve this.

Then the human touch points become coming up with what to build, reviewing the eng plans of the AI, and increasingly light code review of the underlying code, focusing on overall architectural decisions and only occasionally intervening to clean things up (again with AI)