GeminiConfigKeys

Environment-variable names recognised by llm4s-gemini.

Google's GenAI SDKs read two variables for the Gemini API key and prefer GOOGLE_API_KEY when both are set (google-genai's _get_env_api_key: "Both GOOGLE_API_KEY and GEMINI_API_KEY are set. Using GOOGLE_API_KEY."). llm4s-gemini's reference.conf binds both to the shared llm4s.credentials.gemini.apiKey, in that precedence.

Vertex AI has no entry: it authenticates with OAuth2 - Application Default Credentials, or a service-account file named by a section's apiKey - not with an API key.