src/Pure/Tools/server_commands.scala

               Markup.messages.collectFirst({ case (a, b) if b == elem.name =>
                 if (Protocol.is_legacy(elem)) Markup.WARNING else a }) getOrElse ""
             Server.Reply.message(output_text(msg), kind = kind) + position
         }
       }
+
+      def show_message(tree: XML.Tree): Boolean =
+        Protocol.is_exported(tree) || session.show_states && Protocol.is_state(tree)
 
       val result_json =
         JSON.Object(
           "ok" -> result.ok,
           "errors" ->

               val snapshot = result.snapshot(name)
               name.json +
                 ("status" -> status.json) +
                 ("messages" ->
                   (for {
-                    (tree, pos) <- snapshot.messages if Protocol.is_exported(tree)
+                    (tree, pos) <- snapshot.messages if show_message(tree)
                   } yield output_message(tree, pos))) +
                 ("exports" ->
                   (if (args.export_pattern == "") Nil else {
                     val matcher = Export.make_matcher(List(args.export_pattern))
                     for { entry <- snapshot.exports if matcher(entry.entry_name) }