Google Gemini provider implementation.

Supports Gemini models via the Google AI Generative Language API.

Usage

# Basic usage
{:ok, response} = Nous.Providers.Gemini.chat(%{
  model: "gemini-2.0-flash-exp",
  contents: [%{"role" => "user", "parts" => [%{"text" => "Hello"}]}]
})

# With system instruction
{:ok, response} = Nous.Providers.Gemini.chat(%{
  model: "gemini-2.0-flash-exp",
  systemInstruction: %{"parts" => [%{"text" => "You are helpful."}]},
  contents: [%{"role" => "user", "parts" => [%{"text" => "Hello"}]}],
  generationConfig: %{"temperature" => 0.7, "maxOutputTokens" => 1024}
})

# Streaming
{:ok, stream} = Nous.Providers.Gemini.chat_stream(params)
Enum.each(stream, fn event -> IO.inspect(event) end)

Configuration

# In config.exs
config :nous, :gemini,
  api_key: "AIza...",
  base_url: "https://generativelanguage.googleapis.com/v1beta"  # optional

Note on Authentication

Unlike OpenAI/Anthropic which use headers, Gemini uses query parameter auth: ?key=API_KEY

Thinking (Gemini 2.5/3.x)

For models that support extended thinking, pass :thinking_config in default_settings. Both the Elixir shape (snake_case atoms) and the native Vertex shape (camelCase strings) are accepted:

# Elixir shape (recommended)
Nous.new("gemini:gemini-2.5-pro",
  default_settings: %{
    thinking_config: %{thinking_budget: 1024, include_thoughts: true}
  }
)

# Native Vertex shape
Nous.new("gemini:gemini-2.5-pro",
  default_settings: %{
    thinking_config: %{"thinkingBudget" => 1024, "includeThoughts" => true}
  }
)

When include_thoughts: true, thought summaries arrive as Message.reasoning_content. For tool-using thinking models, Vertex emits a thoughtSignature on each tool call; Nous preserves it in tool_call["metadata"]["thought_signature"] and echoes it back on the next turn automatically — required for multi-turn thinking + tool loops to keep working.

See https://ai.google.dev/gemini-api/docs/thinking for the Gemini-side docs and https://cloud.google.com/vertex-ai/generative-ai/docs/thinking for the Vertex equivalent.