src/Pure/Tools/server_commands.scala

       JSON.uuid(json, "session_id")
 
     def command(session: Thy_Resources.Session): (JSON.Object.T, Process_Result) =
     {
       val result = session.stop()
-      val result_json = JSON.Object("return_code" -> result.rc)
+      val result_json = JSON.Object("ok" -> result.ok, "return_code" -> result.rc)
 
       if (result.ok) (result_json, result)
       else throw new Server.Error("Session shutdown failed: return code " + result.rc, result_json)
     }
   }