Google-Extended (Google)

Not a crawler. A robots.txt token that tells Google whether pages Googlebot already fetched may be used to train and ground Gemini. You will never see it in an access log; disallowing it changes what Google does with content it fetched under a different name. Blocking it costs you: You are excluded from Gemini grounding and Gemini training. Google Search ranking and indexing are explicitly unaffected. This is the cleanest 'no training, keep my search traffic' lever that exists. robots.txt token: Google-Extended.