Anthropic just documented how it works. Two marks, both machine-readable: Text: an imperceptible watermark woven into the words themselves. You can’t see it, and it doesn’t change meaning, quality, or readability. Files (.svg, .png, .jpg): signed provenance metadata on the C2PA open standard, so you can tell if a file’s been tampered with. The watermark is applied at the model level. That means it shows up no matter where the text comes from: the API, Claude, Claude Code, Cowork, Cla...