Trait SubscriptionObserver 

pub trait SubscriptionObserver: Send + Sync {
    // Required method
    fn on_close(&self, close: SubscriptionClose);
}

Observes the terminal half of subscriptions/listen streams.

The request half of the observation boundary is ordinary Service<RouterRequest> middleware: transports dispatch the listen request through the service before upgrading, so a layer sees acceptance and rejection like any other method. What that boundary cannot express is the stream’s end, which happens long after the service call returns. This hook carries exactly that remainder and nothing else: implement it for ledger or audit records that need terminal reason and duration, and pair it with a layer for the request half.

Attach with McpRouter::with_subscription_observer; every transport that owns listen streams (stdio, generic stdio, bidirectional stdio, channel, HTTP) reports through it. Calls are made from transport internals, so implementations must be fast and non-blocking.

Required Methods

fn on_close(&self, close: SubscriptionClose)

A subscriptions/listen stream reached its end.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors