[predictabl3]

>You need to remember to stage changes whenever you do Ctrl+S in your editor before rebuilding

This is decidely not quite true. You must have the file visible to Git. Flakes still just uses the files, as long as they're tracked by git. As long as you have no new files that aren't in the index, staging unstaged changes will not change eval.

That said, yes, when you add a new file to a flakes repo, you start to develop a habit of always adding it to the stage/index for eval.

but you should ONLY ever see this as a very very obvious "file not found", it is not a subtle problem as this post implies.

[colordrops]

I concur, this has not been something I've tripped up on. It's pretty obvious when it's the problem.