I don't think they are using any invisible Unicode or metadata stuff.
What happens is that AI selects similar words based on a random process.
Something like "The company had a large/big/substantial advantage".
It chooses between these words, and over a longer piece of text, the pattern will start showing, like a "choice A → choice C → choice C → choice B → choice A".
The normal-looking text will actually be a fingerprint living in the form of statistics.
I think Claude will be sharing these patterns to third parties for AI detection.
What happens is that AI selects similar words based on a random process.
Something like "The company had a large/big/substantial advantage".
It chooses between these words, and over a longer piece of text, the pattern will start showing, like a "choice A → choice C → choice C → choice B → choice A".
The normal-looking text will actually be a fingerprint living in the form of statistics.
I think Claude will be sharing these patterns to third parties for AI detection.