按提示词结论补参数文件默认回落锁

core/src/linuxcnc_rs274_backend.cpp

@@ -183,8 +183,14 @@ int parse_linuxcnc_rs274_backend(CanonEventSink &sink,
         return -1;
     }
 
+    // LinuxCNC source basis: rs274ngc_pre.cc uses
+    // RS274NGC_PARAMETER_FILE_NAME_DEFAULT when the external parameter file
+    // name is empty. Reset the bridge every parse so a prior native env
+    // override does not leak into later default parses.
     if (const char *parameter_file = std::getenv("CNC_SIM_RS274_VAR")) {
         SET_PARAMETER_FILE_NAME(parameter_file);
+    } else {
+        SET_PARAMETER_FILE_NAME("rs274ngc.var");
     }
     cnc_sim_init_minimal_linuxcnc_tooldata();
     sink.clear_callback_status();