Anthropic and xAI start watermarking their text [Nov 1 2026]
Two frontier labs moved to mark the text their models produce. The Decoder, citing a customer email, says Anthropic will extend its text watermark to Claude Mythos 5, Claude Opus 4.7, Claude Opus 4.6 and Claude Sonnet 4.6, and that on Opus 4.6 and Sonnet 4.6 the mark applies only while temperature, top_p and top_k stay at their defaults, so changing one avoids it. Crypto Briefing and TokenPost say xAI will switch invisible statistical watermarking on by default across its Grok API from 7 November for grok-4.7, grok-4.6, grok-4.5, grok-4.3 and grok-4.20, with no developer setting to turn it…
The skinny
The skinny isn't ready yet — notes appear once the transcript is processed.