Xcode 26.6 and 27 Gemini Authentication with Configuration Files

I’m attempting to set up Gemini agentic support in Xcode 26.6 RC (and I'm assuming the process is the same in 27), but since I need to use Gemini with a corporate account, I have a Google Cloud Project ID, not an API key, so it seems like the configuration file route is the right path?

After consulting Gemini and filling out the .env file and settings.json files, Xcode is complaining about needing to be authenticated, and I can’t seem to see how to trigger the auth, like one might do in Gemini CLI.

I'd appreciate any suggestions or advice at this point.

Thanks in advance!

Xcode 26.6 and 27 Gemini Authentication with Configuration Files
 
 
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