diff --git a/core/wasm_shims/emc_status_shim.cc b/core/wasm_shims/emc_status_shim.cc
index 687b9b6..a09138e 100644
--- a/core/wasm_shims/emc_status_shim.cc
+++ b/core/wasm_shims/emc_status_shim.cc
@@ -1,5 +1,5 @@
 #include "nml_intf/emc_nml.hh"
 
-// LinuxCNC src/emc/sai/dummyemcstat.cc uses the same source-backed status
-// object when the interpreter runs without the task controller.
+// LinuxCNC source basis: src/emc/sai/dummyemcstat.cc defines the same
+// source-backed status object when the interpreter runs without task.
 EMC_STAT *emcStatus = new EMC_STAT;
diff --git a/core/wasm_shims/nml_status_shim.cc b/core/wasm_shims/nml_status_shim.cc
index 7fca3c6..6f45c8f 100644
--- a/core/wasm_shims/nml_status_shim.cc
+++ b/core/wasm_shims/nml_status_shim.cc
@@ -4,6 +4,8 @@
 
 #include <cstring>
 
+// LinuxCNC source basis: src/libnml/nml/nmlmsg.cc and stat_msg.cc provide
+// these NML status constructors for source-linked EMC status objects.
 int NMLmsg::automatically_clear = 1;
 
 NMLmsg::NMLmsg(NMLTYPE t, long s) {
diff --git a/core/wasm_shims/rcs_print_shim.cc b/core/wasm_shims/rcs_print_shim.cc
index 93e06ae..6ccda39 100644
--- a/core/wasm_shims/rcs_print_shim.cc
+++ b/core/wasm_shims/rcs_print_shim.cc
@@ -1,6 +1,8 @@
 #include <cstdarg>
 #include <cstdio>
 
+// LinuxCNC source basis: src/libnml/rcs/rcs_print.cc provides these RCS
+// print-error entry points used by NML message validation.
 extern "C" int set_print_rcs_error_info(const char *, int) {
     return 0;
 }
diff --git a/core/wasm_shims/rtapi_compat.cc b/core/wasm_shims/rtapi_compat.cc
index 541ed38..20cf0c5 100644
--- a/core/wasm_shims/rtapi_compat.cc
+++ b/core/wasm_shims/rtapi_compat.cc
@@ -1,6 +1,8 @@
 #include <cstdarg>
 #include <cstdio>
 
+// LinuxCNC source basis: src/rtapi/rtai_rtapi.c provides rtapi_snprintf()
+// for RTAPI-compatible formatting call sites.
 extern "C" int rtapi_snprintf(char *buf, unsigned long size, const char *fmt, ...) {
     va_list ap;
     va_start(ap, fmt);
@@ -8,4 +10,3 @@ extern "C" int rtapi_snprintf(char *buf, unsigned long size, const char *fmt, ..
     va_end(ap);
     return rc;
 }
-
diff --git a/test-linuxcnc-wasm-cmake-safe-probe.sh b/test-linuxcnc-wasm-cmake-safe-probe.sh
index 7329cab..5e26399 100755
--- a/test-linuxcnc-wasm-cmake-safe-probe.sh
+++ b/test-linuxcnc-wasm-cmake-safe-probe.sh
@@ -1444,9 +1444,13 @@ grep -F 'LinuxCNC source basis: src/emc/rs274ngc/interp_namedparams.cc fetch_hal
 grep -F 'LinuxCNC source basis: src/emc/rs274ngc/rs274ngc_pre.cc uses wordexp()' core/wasm_shims/linuxcnc_runtime_shim.cc >/dev/null
 grep -F 'extern "C" int wordexp(const char *words, wordexp_t *pwordexp, int)' core/wasm_shims/linuxcnc_runtime_shim.cc >/dev/null
 grep -F 'extern "C" void wordfree(wordexp_t *pwordexp)' core/wasm_shims/linuxcnc_runtime_shim.cc >/dev/null
+grep -F 'LinuxCNC source basis: src/emc/sai/dummyemcstat.cc defines the same' core/wasm_shims/emc_status_shim.cc >/dev/null
 grep -F 'EMC_STAT *emcStatus = new EMC_STAT;' core/wasm_shims/emc_status_shim.cc >/dev/null
+grep -F 'LinuxCNC source basis: src/libnml/nml/nmlmsg.cc and stat_msg.cc provide' core/wasm_shims/nml_status_shim.cc >/dev/null
 grep -F 'wasm_shims/nml_status_shim.cc' core/CMakeLists.txt >/dev/null
+grep -F 'LinuxCNC source basis: src/libnml/rcs/rcs_print.cc provides these RCS' core/wasm_shims/rcs_print_shim.cc >/dev/null
 grep -F 'wasm_shims/rcs_print_shim.cc' core/CMakeLists.txt >/dev/null
+grep -F 'LinuxCNC source basis: src/rtapi/rtai_rtapi.c provides rtapi_snprintf()' core/wasm_shims/rtapi_compat.cc >/dev/null
 grep -F '$<TARGET_OBJECTS:linuxcnc_rs274_wasm_safe_probe_objects>' core/CMakeLists.txt >/dev/null
 grep -F '$<TARGET_OBJECTS:cnc_sim_objects>' core/CMakeLists.txt >/dev/null
 grep -F 'CNC_SIM_ENABLE_LINUXCNC_RS274_BACKEND' core/CMakeLists.txt >/dev/null