When senior engineers stop writing the code

The fastest senior engineers we work with don't open the editor anymore. They open a chat, decompose the task, and let the agent write the first draft. The interesting work starts after that.

This shift surprises traditional engineering managers. The instinct is to read it as "senior engineers are getting lazy" or "they're just using AI to avoid the hard parts." That instinct is wrong. The first draft of a function is no longer where the value is — it's the verification, the decomposition, and the architecture decisions that frame the problem before any code exists.

Three things change when seniors stop writing the first draft:

1. They spend more time on edges. Inputs, error cases, what happens at scale. The agent will give you a working happy path. The senior's job is to make sure the unhappy paths are right.
2. Code review gets sharper. When you didn't write it, you read it more carefully. We see seniors flagging issues in agent-written code that they'd have glossed over in their own.
3. Architecture happens upstream. The decomposition is the deliverable. If the senior can write a clean spec and break the problem into well-scoped tasks, the agent fills in the implementation.

The teams that are stuck still treat AI as a typing accelerator — autocomplete on steroids. The teams that ship treat it as a junior engineer that needs spec'd work and careful review. Same tools, different operating model.