At
@ElixirConfEU,
@chris_mccord and I set up two races between myself and a coding agent. One was to add a new feature to DBConnection (max_lifetime) and another was to investigate a potential type system regression (links below).
For DBConnection, I gave the documentation of how the option would behave. Not only was I faster, the coding agent solution had 4x more LOC than mine (it changed files and data structures that were not necessary for the feature).
For the type system, the coding agent could not fix the problem at all. It did recognise it was a type system regression, and it did provide an initial fix in roughly the same time as I did, but the coding agent fix was wrong. After I fed it additional tests (from my own solution), it failed to come up with a fix.
I use coding agents daily, I often ship their code as is, but they can still slow me down, they are nowhere close to fixing all problems I tackle in a given week, and are often not up to the standards I expect from my own software.