Type Alias BeforeAgentCallback 

pub type BeforeAgentCallback = Box<dyn Fn(Arc<dyn CallbackContext>) -> Pin<Box<dyn Future<Output = Result<Option<Content>, AdkError>> + Send>> + Sync + Send>;

Core traits and types.

Always available regardless of feature flags. Includes:

• Agent - The fundamental trait for all agents
• Tool / Toolset - For extending agents with capabilities
• Session / State - For managing conversation context
• Event - For streaming agent responses
• AdkError / Result - Unified error handling

Aliased Type

pub struct BeforeAgentCallback(/* private fields */);