Watermarking without quality loss is a bit unintuitive, doesn't feel like it sho

Anthropic describes Claude's text watermark as a pattern in word selection, without added characters. Its technical FAQ says a secret key and preceding text guide the randomness used to choose among plausible next words. A detector can then assess whether a passage's choices are consistent with that key. The company reports no quality impact in its internal testing. Detection becomes weaker when there are few discretionary choices, as in short passages or human-written text that Claude only lightly edited. The result is a probabilistic indication of Claude's involvement, rather than proof of who wrote every word.