Dommedia Sign-in Guard for Gemini

Blocks access to Google Gemini unless a Google account is signed in. Not affiliated with or endorsed by Google.

Dommedia Sign-in Guard for Gemini makes one rule hold in every tab: Google Gemini cannot be reached without a signed-in Google account. It is built for organisations that allow Gemini for staff on a corporate account but not anonymously, where an unauthenticated session sits outside the controls that make the tool acceptable in the first place. HOW IT WORKS When there is no Google session, requests to Gemini are stopped at the network layer and the tab shows a page explaining why, with a link to sign in. Anonymous Gemini is never requested, not merely closed after it opens. Signing in lifts the block immediately and returns you to the page you were trying to reach. If the session later ends, any tab sitting on Gemini is locked again. WHAT IT DOES NOT DO - It does not read the content of any page, on Gemini or anywhere else. - It does not send anything anywhere. There is no account, no server, no analytics and no telemetry. Every decision is made inside your browser. - It leaves the rest of your browsing completely alone. Sites other than Gemini are never inspected or affected. - It runs no remotely hosted code. HOW IT DECIDES It checks whether Google's session cookies are present for google.com. Only their presence is used - the values are never stored, logged or transmitted, and no cookies for any other site are read. These cookies are httpOnly, which is why the extension reads them through the browser's cookie API rather than from the page. FOR ADMINISTRATORS Requests to Gemini carry an identifying product token, in the X-GeminiAuthOnly header and appended to the User-Agent, so a proxy or CASB rule can recognise traffic from a managed browser. The token identifies the extension, not the user. Force-installing by policy is supported, which is what makes the rule binding: a force-installed extension cannot be disabled or removed by the user. In InPrivate or Incognito the extension needs to be allowed there explicitly, or it does not run. Dommedia Sign-in Guard for Gemini is not affiliated with, endorsed by, or sponsored by Google. Gemini is a trademark of Google LLC.