Stamp a ledger operation with the caller the runner proved for the call in flight it names, refusing another module's call or one not in flight; serve the ledger calls on the pipe (issue 1966 T5)

node-tools/internal/launch/event_answer_test.go

@@ -52,6 +52,7 @@ func (b *subscribing) BusState(string, json.RawMessage) (json.RawMessage, error)
 func (b *subscribing) BusStateWatch(string, json.RawMessage, func(json.RawMessage) error) (func(), error) {
 	return func() {}, nil
 }
+func (b *subscribing) Begin(string) (string, func()) { return "", func() {} }
 func (b *subscribing) Subscribe(d func(json.RawMessage) error) error {
 	b.mu.Lock()
 	defer b.mu.Unlock()