What it was for
The PRD served two masters: a persuasion document that won stakeholders, and a translation document that told engineers what to build. It was written for human readers, judged by its narrative, and routinely outdated before the build it described had finished.
The verdict
TRANSFORMS. In the engine, the PRD's translation function is absorbed into intent specification — and the standard changes from convincing to executable. A requirement now has a new and unforgiving reader: a machine that will do exactly what the document says, at speed, including the ambiguities. Prose that a charitable engineer would have quietly repaired, the inner loop will faithfully ship.
What changes
The artifact splits along its two old jobs. The persuasion half remains human writing — context, stakes, the why — and gets shorter and more honest. The translation half hardens into machined intent: acceptance criteria as evaluations, constraints stated as rules, edge cases enumerated rather than implied. "The team will figure it out" stops being a sentence a PM can write, because the team that figures it out now includes machines that figure it out wrong, confidently.
The strongest objection
Over-specification was the disease waterfall died of; this sounds like its return. Conceded as the failure mode to watch — but the cure differs from the disease. Waterfall specified everything once, upfront, blind. The engine specifies one intent per revolution, against evidence, continuously. Precision per loop, not prophecy per year.