Google Gemini

Rho uses Google's native Gemini generateContent API. It supports streamed text, thought summaries, images, function calls and responses, thought-signature replay, and provider-reported token use.

Setting	Value
Provider	google
Auth mode	google-api-key
Environment override	GEMINI_API_KEY
API	https://generativelanguage.googleapis.com/v1beta

Login

Create a Gemini API key in Google AI Studio, then run:

/login google

Rho stores the key in the configured credential store. For CI or local development, set GEMINI_API_KEY instead. The environment value takes priority over the stored key.

Google AI Studio offers a free tier for selected models. Google may use free-tier request content to improve its products, so use synthetic prompts and do not send private source code or secrets when testing on that tier.

Logout

Run /logout google to remove the Google API key from the configured credential store. If GEMINI_API_KEY is set, that environment override remains active after logout.

Models

Open /config and choose Refresh model lists. Rho reads Google's Models API, keeps text chat models that support generateContent, and caches their input and output token limits. Then select a model, for example:

/model google/gemini-3.1-flash-lite

Google may add, rename, or retire models, so refresh the list when a model is missing. Rho uses models.dev lifecycle metadata to hide exact model IDs marked as deprecated. If models.dev is unavailable or does not know an ID, Rho keeps the model returned by Google visible.

Reasoning and tools

Rho maps its reasoning levels to Gemini 3 thinking levels and Gemini 2.5 thinking budgets. It rejects levels a model cannot honor rather than silently selecting a higher level. Thought summaries stay separate from raw reasoning, and Gemini thought signatures remain opaque. Rho replays those signatures only to the exact same provider, API, and model.

Tool declarations use Gemini function declarations. Tool calls and function responses retain their call IDs when Google supplies them. Rho creates a unique local ID when a response omits one, while leaving the ID absent on later Google requests.