Trait Hook 

pub trait Hook: Send + Sync {
    // Provided methods
    fn on_build_agent(&self, config: AgentConfig) -> AgentConfig { ... }
    fn on_event(&self, _agent: &str, _event: &AgentEvent) { ... }
    fn on_register_tools(
        &self,
        _tools: &mut ToolRegistry,
    ) -> impl Future<Output = ()> + Send { ... }
}

Lifecycle backend for agent building, event observation, and tool registration.

Default implementations are no-ops so implementors only override what they need.

Provided Methods

fn on_build_agent(&self, config: AgentConfig) -> AgentConfig

Called by Runtime::add_agent() before building the Agent.

Enriches the agent config: appends skill instructions, injects memory into the system prompt, etc. The returned config is passed to AgentBuilder.

Default: returns config unchanged.

fn on_event(&self, _agent: &str, _event: &AgentEvent)

Called by Runtime after each agent step during execution.

Receives every AgentEvent produced during send_to and stream_to. Use for logging, metrics, persistence, or forwarding.

Default: no-op.

fn on_register_tools( &self, _tools: &mut ToolRegistry, ) -> impl Future<Output = ()> + Send

Called by Runtime::new() to register tools into the shared registry.

Implementations insert (Tool, Handler) pairs via tools.insert(). DaemonHook delegates to each sub-hook’s on_register_tools.

Default: no-op async.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl Hook for ()

Implementors

impl Hook for InMemory