The output is the program behavior. You use it, like a user, and give feedback to the coding agent.

If the app is too bright, you tweak the settings and build it again.

Photography used to involve developing film in dark rooms. Now my iPhone does... god knows what to the photo - I just tweak in post, or reshoot. I _could_ get the raw, understand the algorithm to transform that into sRGB, understand my compression settings, etc - but I don't need to.

Similarly, I think there will be people who create useful software without looking at what happens in between. And there will still be low-level software engineers for whom what happens in between is their job.