TransportType<R, W> supports an optional getMessageContext(message: unknown): unknown method.
Transports can expose local metadata for a received message without changing its serialised representation.
The server passes this metadata to the invocation hook as InvocationContext.transport.
The base Transport does not implement this optional method. Existing transports need no changes.
Custom transports can implement the method and return a more specific context type.
The server receives undefined when the method is absent.
Callers should narrow the returned unknown value before accessing its fields.
The HTTP server transport exposes the original HTTP request and optional SSE session metadata.
See the HTTP server transport documentation for its context and ownership APIs.