Complete notification expiry and configurable durable delivery (#36)

backend/notifications/transport/server.go

@@ -77,6 +77,12 @@ func Authenticate(tokens map[string]string) grpc.UnaryServerInterceptor {
 	}
 }
 func rpcError(err error) error {
+	if errors.Is(err, context.Canceled) {
+		return status.Error(codes.Canceled, "notification operation canceled")
+	}
+	if errors.Is(err, context.DeadlineExceeded) {
+		return status.Error(codes.DeadlineExceeded, "notification operation deadline exceeded")
+	}
 	for _, pair := range []struct {
 		err     error
 		code    codes.Code