Claude 4.5 Opus' Soul Document

I understand it's not a system prompt so there's some novelty there I suppose. Is it because someone was able to get Claude to regurgitate a (very large) document from its training data? Or is it the content of the document itself?

I've only skimmed it and there's probably some unique nuggets here and there, but at a high level the rules/guidelines didn't really jump out at me as being much different than the various system prompts for proprietary models made public over the last couple years. Except much longer (and a bit ramble-y in some sections vs the directness of typical system prompt).

Of course, it might to happen anyway. DeepSeek models frequently think they are every other model if prompted. Claude Sonnet/Opus 4.5, when they do web searches, also tend to think they wrote the web search text when they quote it IME.