diff --git a/build-linuxcnc-wasm-link-probe.sh b/build-linuxcnc-wasm-link-probe.sh
index bda88d5..18796c1 100755
--- a/build-linuxcnc-wasm-link-probe.sh
+++ b/build-linuxcnc-wasm-link-probe.sh
@@ -87,6 +87,7 @@ case "$mode" in
         main_source=core/wasm_shims/cnc_sim_wasm_runtime_probe_main.cc
         target_name=cnc_sim_wasm_runtime_probe
         common_flags+=(-DCNC_SIM_ENABLE_LINUXCNC_RS274_BACKEND)
+        grep -F 'LinuxCNC source basis: src/emc/rs274ngc/rs274ngc_pre.cc provides read(),' "$main_source" >/dev/null
         ;;
 esac
 
diff --git a/core/wasm_shims/cnc_sim_wasm_runtime_probe_main.cc b/core/wasm_shims/cnc_sim_wasm_runtime_probe_main.cc
index d40eceb..9316c1b 100644
--- a/core/wasm_shims/cnc_sim_wasm_runtime_probe_main.cc
+++ b/core/wasm_shims/cnc_sim_wasm_runtime_probe_main.cc
@@ -7,6 +7,8 @@
 #include <vector>
 #include <wordexp.h>
 
+// LinuxCNC source basis: src/emc/rs274ngc/rs274ngc_pre.cc provides read(),
+// execute(), and wordexp() paths; interp_convert.cc converts G0, G2, and M30.
 namespace {
 
 int collect_event(const CncSimEvent *event, void *user_data) {
diff --git a/test-linuxcnc-wasm-cmake-safe-probe.sh b/test-linuxcnc-wasm-cmake-safe-probe.sh
index 0ca8bda..ab1edb5 100755
--- a/test-linuxcnc-wasm-cmake-safe-probe.sh
+++ b/test-linuxcnc-wasm-cmake-safe-probe.sh
@@ -1359,6 +1359,7 @@ grep -F "wasm_shims/rs274ngc_pre_probe_main.cc" core/CMakeLists.txt >/dev/null
 grep -F 'LinuxCNC source basis: src/emc/rs274ngc/rs274ngc_pre.cc provides' core/wasm_shims/rs274ngc_pre_probe_main.cc >/dev/null
 grep -F "target_compile_definitions(linuxcnc_rs274_wasm_safe_probe" core/CMakeLists.txt >/dev/null
 grep -F "wasm_shims/cnc_sim_wasm_runtime_probe_main.cc" core/CMakeLists.txt >/dev/null
+grep -F 'LinuxCNC source basis: src/emc/rs274ngc/rs274ngc_pre.cc provides read(),' core/wasm_shims/cnc_sim_wasm_runtime_probe_main.cc >/dev/null
 grep -F "add_executable(cnc_sim_wasm_runtime_probe EXCLUDE_FROM_ALL" core/CMakeLists.txt >/dev/null
 grep -F "target_link_libraries(linuxcnc_rs274_wasm_safe_probe PRIVATE fmt)" core/CMakeLists.txt >/dev/null
 grep -F "target_link_libraries(cnc_sim_wasm_runtime_probe PRIVATE fmt)" core/CMakeLists.txt >/dev/null