aether_core/events/
observer.rs

1use crate::events::{AgentEvent, TraceContext};
2use std::sync::Arc;
3
4/// Observer of the agent's event stream. Observers receive the same events
5/// the agent sends on its event channel, synchronously and in order —
6/// including events that channel consumers such as UIs and session
7/// persistence filter out downstream.
8pub trait AgentObserver: Send {
9    fn on_event(&mut self, message: &AgentEvent);
10
11    /// Trace context to propagate to whatever executes `tool_id`, available once
12    /// the observer has seen that tool's
13    /// [`ExecutionStarted`](crate::events::ToolEvent::ExecutionStarted).
14    fn tool_trace_context(&self, _tool_id: &str) -> Option<TraceContext> {
15        None
16    }
17}
18
19/// Instrumentation for one inbound MCP request, held by the server handling it.
20pub trait McpRequestInstrumentation: Send {
21    /// Context beneath the request, for application work the request spawns.
22    fn trace_context(&self) -> Option<TraceContext>;
23
24    /// Completes the request. `error` is the public operation error, if any.
25    fn finish(self: Box<Self>, error: Option<&str>);
26}
27
28/// Creates observers isolated to one agent or one inbound MCP request.
29pub trait ObserverFactory: Send + Sync {
30    /// A fresh observer for one agent, continuing the parent trace when supplied.
31    fn agent(&self, agent_name: Option<&str>, parent: Option<&TraceContext>) -> Box<dyn AgentObserver>;
32
33    /// Instrumentation for one inbound `tools/call` request.
34    fn tool_call_request(&self, tool_name: &str, parent: Option<&TraceContext>) -> Box<dyn McpRequestInstrumentation>;
35}
36
37pub type DynObserverFactory = Arc<dyn ObserverFactory>;
aether_core/events/observer.rs

aether_core/events/
observer.rs
