Nah, it's totally Claude. No human writes the bulleted list in https://github.com/RokoMijic/MercurialDyson/blob/4f6cb3c0b5b..., or "The thermal management problem that naively prohibits rapid disassembly is resolved by three key insights…". The whole thing reeks of Claude, but chapters 12 and 13 are probably the clearest slam-dunks.

If you want to compare styles, https://github.com/Smaug123/gospel/blob/764996d20e11674f9221... is similarly written almost entirely by Opus (4.5 rather than 4.6) with some strong LessWrong-o-sphere background prompting and the instruction to be terse. The styles are practically identical.