按建议，继续完成后续工作

结论：将解释器外部长度单位读取接入共享 emcStatus 状态边界，并补充 inch/mm 初始化验证。

wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_emc_status_probe.cpp

@@ -2,9 +2,6 @@
 
 #include <iostream>
 
-static EMC_STAT standalone_emc_status;
-EMC_STAT *emcStatus = &standalone_emc_status;
-
 int main()
 {
     const bool default_units_visible = emcStatus->motion.traj.linearUnits == 1.0;

wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_emc_status_runtime.cpp

@@ -0,0 +1,4 @@
+#include "nml_intf/emc.hh"
+
+static EMC_STAT standalone_emc_status;
+EMC_STAT *emcStatus = &standalone_emc_status;

wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_interp_init_harness.cpp

@@ -8,6 +8,7 @@
 #include <unistd.h>
 
 #include "canon_event_sink.hh"
+#include "nml_intf/emc.hh"
 
 namespace {
 
@@ -29,6 +30,7 @@ int main()
     const auto temp_dir = make_temp_dir();
     std::filesystem::current_path(temp_dir);
 
+    emcStatus->motion.traj.linearUnits = 1.0;
     Interp interp;
     standalone::reset_canon_events();
 
@@ -44,6 +46,21 @@ int main()
         std::cout << "canon_event=" << event << "\n";
     }
 
+    emcStatus->motion.traj.linearUnits = 1.0 / 25.4;
+    Interp inch_interp;
+    standalone::reset_canon_events();
+    const int inch_rc = inch_interp.init();
+    std::cout << "inch_init=" << inch_rc << "\n";
+    std::cout << "inch_setup.length_units="
+              << static_cast<int>(inch_interp._setup.length_units) << "\n";
+    std::cout << "inch_external_length_units="
+              << GET_EXTERNAL_LENGTH_UNITS() << "\n";
+    std::cout << "inch_canon_event_count=" << standalone::canon_events().size() << "\n";
+    for (const auto &event : standalone::canon_events()) {
+        std::cout << "inch_canon_event=" << event << "\n";
+    }
+
+    emcStatus->motion.traj.linearUnits = 1.0;
     std::filesystem::remove_all(temp_dir);
-    return rc == INTERP_OK ? 0 : 1;
+    return (rc == INTERP_OK && inch_rc == INTERP_OK) ? 0 : 1;
 }

wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_interp_minimal_runtime.cpp

@@ -13,6 +13,7 @@
 #include "emc/rs274ngc/rs274ngc_return.hh"
 #include "canon_event_sink.hh"
 #include "linuxcnc_tool_adapter.hh"
+#include "nml_intf/emc.hh"
 
 namespace standalone {
 
@@ -448,8 +449,11 @@ void CANON_ERROR(const char *fmt, ...)
 
 double GET_EXTERNAL_FEED_RATE() { return 0.0; }
 int GET_EXTERNAL_FLOOD() { return 0; }
-CANON_UNITS GET_EXTERNAL_LENGTH_UNIT_TYPE() { return CANON_UNITS_MM; }
-double GET_EXTERNAL_LENGTH_UNITS() { return 1.0; }
+CANON_UNITS GET_EXTERNAL_LENGTH_UNIT_TYPE()
+{
+    return (emcStatus->motion.traj.linearUnits > 0.5) ? CANON_UNITS_MM : CANON_UNITS_INCHES;
+}
+double GET_EXTERNAL_LENGTH_UNITS() { return emcStatus->motion.traj.linearUnits; }
 double GET_EXTERNAL_ANGLE_UNITS() { return 1.0; }
 int GET_EXTERNAL_MIST() { return 0; }
 CANON_MOTION_MODE GET_EXTERNAL_MOTION_CONTROL_MODE() { return CANON_EXACT_STOP; }