The control stack has displaced prompt engineering.

The pattern converging across practitioner writing this month is four layers around the model: project rules, reusable skills, bounded sub-agents, deterministic tools, with human checkpoints between stages (Developers Digest). The claim is that decomposition into bounded subtasks beats one long run not because the model is weak but because bounded scopes are verifiable. That's the right reason. And it now buildable off the shelf rather than assembled by hand.