You mean trying and failing to build a C compiler. This isn't a very hard task to begin with (assuming you know compilers, and the models do), but it was made unrealistically easy by giving the agents thousands of tests written by humans over years (on top of a spec and a reference implementation, both of which the models were trained on), and the agents still failed to converge. I was actually surprised that they failed as this was the purest possible example of "just do the coding" (something that isn't achievable in real or more complex cases) and when I read the description I thought they made it too easy, and in a way that isn't representative of real software. My thought at that failure was that if agents can't even build a C compiler with so much preparation effort put into the test, then we have some ways to go. Indeed, once you work a lot with agents for a while you see that coding isn't really their strong suit (although they are impressive at debugging).