Struct SessionConfig 

pub struct SessionConfig {

    pub endpoint: ApiEndpoint,
    pub model: GeminiModel,
    pub generation_config: GenerationConfig,
    pub system_instruction: Option<Content>,
    pub tools: Vec<Tool>,
    pub tool_config: Option<ToolConfig>,
    pub input_audio_transcription: Option<InputAudioTranscription>,
    pub output_audio_transcription: Option<OutputAudioTranscription>,
    pub realtime_input_config: Option<RealtimeInputConfig>,
    pub session_resumption: Option<SessionResumptionConfig>,
    pub context_window_compression: Option<ContextWindowCompressionConfig>,
    pub proactivity: Option<ProactivityConfig>,
    pub input_audio_format: AudioFormat,
    pub output_audio_format: AudioFormat,
    pub input_sample_rate: u32,
    pub output_sample_rate: u32,
}

Complete session configuration — the builder entrypoint.

Fields

endpoint: ApiEndpoint

API endpoint and credentials (Google AI key or Vertex AI project/token).

model: GeminiModel

Which Gemini model to use.

generation_config: GenerationConfig

Generation parameters (modalities, temperature, etc.).

system_instruction: Option<Content>

System instruction content.

tools: Vec<Tool>

Tool declarations for function calling, search, etc.

tool_config: Option<ToolConfig>

Tool usage configuration.

input_audio_transcription: Option<InputAudioTranscription>

Input audio transcription configuration.

output_audio_transcription: Option<OutputAudioTranscription>

Output audio transcription configuration.

realtime_input_config: Option<RealtimeInputConfig>

Realtime input configuration (VAD, activity handling).

session_resumption: Option<SessionResumptionConfig>

Session resumption configuration.

context_window_compression: Option<ContextWindowCompressionConfig>

Context window compression configuration.

proactivity: Option<ProactivityConfig>

Proactivity configuration.

input_audio_format: AudioFormat

Audio format for input (default: PCM16).

output_audio_format: AudioFormat

Audio format for output (default: PCM16).

input_sample_rate: u32

Input audio sample rate in Hz (default: 16000).

output_sample_rate: u32

Output audio sample rate in Hz (default: 24000).

Implementations

impl SessionConfig

pub fn to_setup_message(&self) -> SetupMessage

Build the setup message from this configuration.

When targeting Vertex AI, FunctionCallingBehavior is stripped from tool declarations since Vertex AI does not support async tool calling.

pub fn to_setup_json(&self) -> String

Pre-serialize the setup message to JSON. Called once at connection time.

impl SessionConfig

pub fn new(api_key: impl Into<String>) -> Self

Create a new session configuration with a Google AI API key.

This is the simplest way to get started. For Vertex AI, use SessionConfig::from_vertex or SessionConfig::from_endpoint.

pub fn from_access_token(access_token: impl Into<String>) -> Self

Create a session configuration with an OAuth2 access token.

Uses the Google AI endpoint (generativelanguage.googleapis.com) with an access token instead of an API key. This is the recommended approach when using gcloud auth print-access-token credentials.

let config = SessionConfig::from_access_token("ya29.ACCESS_TOKEN");

pub fn from_vertex( project: impl Into<String>, location: impl Into<String>, access_token: impl Into<String>, ) -> Self

Create a session configuration for Vertex AI.

Uses the regional Vertex AI endpoint ({location}-aiplatform.googleapis.com). For the global endpoint, consider using SessionConfig::from_access_token instead.

let config = SessionConfig::from_vertex(
    "my-project-123",
    "us-central1",
    "ya29.ACCESS_TOKEN",
);

pub fn from_endpoint(endpoint: ApiEndpoint) -> Self

Create a session configuration from an explicit ApiEndpoint.

pub fn model(self, model: GeminiModel) -> Self

Set the Gemini model.

pub fn voice(self, voice: Voice) -> Self

Set the output voice.

pub fn system_instruction(self, instruction: impl Into<String>) -> Self

Set the system instruction.

pub fn response_modalities(self, modalities: Vec<Modality>) -> Self

Set response modalities.

pub fn text_only(self) -> Self

Configure for text-only mode (no audio output).

pub fn add_tool(self, tool: Tool) -> Self

Add a tool declaration.

pub fn with_url_context(self) -> Self

Enable URL context tool.

pub fn with_google_search(self) -> Self

Enable Google Search grounding.

pub fn with_code_execution(self) -> Self

Enable code execution.

pub fn tool_config(self, config: ToolConfig) -> Self

Set tool configuration.

pub fn enable_input_transcription(self) -> Self

Enable input audio transcription.

pub fn enable_output_transcription(self) -> Self

Enable output audio transcription.

pub fn temperature(self, temp: f32) -> Self

Set the temperature for generation.

pub fn server_vad(self, detection: AutomaticActivityDetection) -> Self

Configure server-side VAD.

pub fn activity_handling(self, handling: ActivityHandling) -> Self

Set how incoming audio interacts with model output (barge-in behavior).

pub fn turn_coverage(self, coverage: TurnCoverage) -> Self

Set which input counts toward a user’s conversation turn.

pub fn voice_realtime_defaults(self) -> Self

Apply recommended realtime input defaults for voice conversations.

This preserves any values the caller already set. In particular, it sets TURN_INCLUDES_ONLY_ACTIVITY so long pauses/silence in a continuous mic stream are not included in the user’s semantic turn.

pub fn session_resumption(self, handle: Option<String>) -> Self

Enable session resumption.

pub fn context_window_compression(self, target_tokens: u32) -> Self

Configure context window compression for long sessions.

pub fn context_window_trigger_tokens(self, tokens: u32) -> Self

Set the token threshold that triggers context window compression.

pub fn proactive_audio(self, enabled: bool) -> Self

Enable proactive model responses.

pub fn thinking(self, budget: u32) -> Self

Enable thinking/reasoning with a token budget (Gemini 2.5+).

pub fn include_thoughts(self) -> Self

Include the model’s thought process in responses.

pub fn affective_dialog(self, enabled: bool) -> Self

Enable affective dialog (emotionally expressive responses).

pub fn media_resolution(self, res: MediaResolution) -> Self

Set the media resolution for image/video inputs.

pub fn seed(self, seed: u32) -> Self

Set the random seed for deterministic generation.

pub fn input_audio(self, format: AudioFormat, sample_rate: u32) -> Self

Set input audio format and sample rate.

pub fn output_audio(self, format: AudioFormat, sample_rate: u32) -> Self

Set output audio format and sample rate.

pub fn ws_url(&self) -> String

Build the WebSocket URL for connecting to the Gemini Live API.

• Google AI (key): wss://generativelanguage.googleapis.com/ws/...?key={key}
• Google AI (token): wss://generativelanguage.googleapis.com/ws/...?access_token={token}
• Vertex AI: wss://{location}-aiplatform.googleapis.com/ws/... or wss://aiplatform.googleapis.com/ws/... for global

pub fn model_uri(&self) -> String

Build the model URI used in the setup message.

• Google AI / Google AI Token: models/{model}
• Vertex AI: projects/{project}/locations/{location}/publishers/google/models/{model}

pub fn bearer_token(&self) -> Option<&str>

Returns the bearer token when using Vertex AI, None for Google AI.

Used by the transport layer to set the Authorization HTTP header during the WebSocket upgrade handshake. Google AI endpoints pass the token as a query parameter instead.

pub fn is_vertex(&self) -> bool

Returns true if this config targets Vertex AI.

pub fn supports_async_tools(&self) -> bool

Returns true if the platform supports async (non-blocking) tool calling.

Google AI supports FunctionCallingBehavior::NonBlocking on declarations and FunctionResponseScheduling on responses. Vertex AI does not — these fields are automatically stripped from the wire messages when targeting Vertex AI so callers can set them unconditionally.

pub fn uses_access_token(&self) -> bool

Returns true if this config uses an access token (either GoogleAIToken or VertexAI).

Trait Implementations

impl Clone for SessionConfig

fn clone(&self) -> SessionConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SessionConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.