> None of this was free. Through the summer, much of our engineering effort went into tests and tooling, and customer-facing changes per engineer stayed between 17 and 30 a month

This is the reality I think for a lot of orgs and is absorbing a lot of the productivity gains. The gap between vibe coding a green field app from nothing which is inherently "AI native" and implementing AI tooling into complex orgs with large amounts of legacy infrastructure, integrations, ingrained practices etc is enormous. For us, it has been a big effort to enable agentic coding over a significant footprint of our codebase. And all this is happening while the plane keeps flying, with near zero tolerance for defects in critical systems. There is a lot more to it than you will understand if you just look at twitter or Hacker News.