The people doing this work as a career and not performative art, who were already good at their job, had no worries about this to begin with.

The code was always a black box. Always.

Specs come in, passing tests come out. If you find an issue, your specs were shit.

Anyone that has ever had to outsource work to someone else knows this. If you've ever worked with another team whose codebase you didn't touch - you know this.

You write your specs, you launch an agent to implement them. You launch a 2nd agent to keep the first one honest. When done, you launch as many agents as you have budget to try and poke holes in the implementation. As it always was the case.

You can thrash around (and you will), you can fight it (and you will). Like it or not, the genie is out of the box, and the realization you were never really good at your job to begin with is gonna set in eventually.