Function prepare_request 

pub async fn prepare_request(
    agent: &dyn Agent,
    conversation: &[Message],
    provider: &dyn AiProvider,
    settings_manager: SettingsManager,
    steering: &SteeringDocuments,
    tools: Vec<Arc<dyn ToolExecutor>>,
    prompt_builder: &PromptBuilder,
    context_builder: &ContextBuilder,
    modules: &[Arc<dyn Module>],
) -> Result<(ConversationRequest, ModelSettings)>

Prepare an AI conversation request. This handles the work of fully assembling a request - including building the prompt (from the agent and prompt_builder), the context message (from the context_builder), selecting the correct model, etc.