UnhandledMethodHandler

Opt-in fallback for services that want to handle incoming RPC calls targeting method names that are not registered on the service.

An RpcService may implement this interface in addition to its normal com.monkopedia.ksrpc.annotation.KsMethod-annotated endpoints. When a call arrives for an endpoint that RpcObject.findEndpoint does not recognize, ksrpc will route the call to onUnhandled instead of immediately returning an RpcEndpointException to the caller.

The handler receives the raw CallData payload for the call and must return a CallData payload to be serialized back to the caller. This type is transport agnostic — it's the same envelope that core's dispatch path passes around for every call, so implementations work unchanged across every ksrpc transport (JSON-RPC, packet-framed, JNI, etc.).

Exceptions thrown from onUnhandled are reported back to the caller as remote errors, identical to the path taken when a normal handler throws.

This is a receiver-side fallback: senders dispatch exactly as they do today. Services that do not implement this interface preserve the existing unknown-endpoint error behavior.