How likely is it that the former year's code was in the training data, or that the (perhaps unreleased, beta version) of Claude Code that Dogan was using somehow had access to it, unbeknownst to the team?
This also plays into my own intuition of using the latest coding agents. They don't need to have seen a system before in order to build it for you if you know how to describe it.
I can describe a project I never released myself in a couple of detailed paragraphs and get a great implementation.