Function run_agent_loop 

pub async fn run_agent_loop(
    model: Arc<RwLock<Box<dyn Model>>>,
    config: &ModelConfig,
    messages: &mut Vec<ChatMessage>,
    initial_tool_calls: Vec<ToolCall>,
    observer: &mut dyn AgentObserver,
    max_iterations: usize,
) -> Result<AgentLoopResult>

Run the agent loop: execute tool calls, feed results back, repeat.

This is the core loop shared by TUI and non-interactive modes. The observer trait provides environment-specific behavior.