Nothing Here Is New
Read the previous two lessons back and they can sound like an elaborate ritual invented to manage a machine. They are not. A real author and a real publisher have run exactly this pipeline for as long as publishing has existed, often several readers deep, and every stage of it exists for the reason this workshop rediscovered by measurement.
The author writes. A developmental editor reads for whether the thing holds together — and is deliberately not the author, because the author cannot see the gap between what is on the page and what is in their head. A copy editor reads for language, sentence by sentence, and is given the manuscript rather than the author's intentions. A proofreader reads the final proof without the manuscript it came from, precisely so that they cannot unconsciously repair a defect by remembering what was meant. Beta readers read cold and report where they got confused, not why.
What the Industry Version Tells You That the Software Version Forgets
Three things, and each maps onto a decision this workshop had to make the hard way.
The roles are separated by what they may see, not by seniority. A proofreader is not a junior copy editor. They are a reader with strictly less information, on purpose, because the reduction is the instrument.
Nobody treats it as an insult. An author who objected that a copy editor was implying they could not write would be misunderstanding the craft. The boundary is about position, not competence, and publishing worked that out centuries before anyone had to explain it to an engineering team.
The passes are named, ordered, and priced. They are not a checklist bolted onto the end of a schedule; they are the schedule. A house that skips the copy edit does not save a pass, it ships a different quality of book, and everyone in the building knows which houses do that.
The Only Real Difference
In publishing, the boundary is maintained by the fact that people are separate. Here it has to be built, because the same system can be asked to do all the roles and will say yes to each of them. That is not a reason to invent a new process. It is a reason to implement the old one with a harness where the industry has staffing.