diff --git a/test-linuxcnc-wasm-interp-base-link.sh b/test-linuxcnc-wasm-interp-base-link.sh
index f49561f..5db2fce 100755
--- a/test-linuxcnc-wasm-interp-base-link.sh
+++ b/test-linuxcnc-wasm-interp-base-link.sh
@@ -3,6 +3,8 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: the standalone probe links src/emc/rs274ngc/interp_base.cc,
+# whose runtime dynamic loading edge is satisfied by the wasm-safe dlfcn shim.
 probe=$(./build-linuxcnc-wasm-standalone-probe.sh --mode interp-base-link)
 
 "$probe"
diff --git a/test-linuxcnc-wasm-python-c-api-symbols.sh b/test-linuxcnc-wasm-python-c-api-symbols.sh
index e50c583..f7a8b92 100755
--- a/test-linuxcnc-wasm-python-c-api-symbols.sh
+++ b/test-linuxcnc-wasm-python-c-api-symbols.sh
@@ -3,6 +3,10 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: this probe derives required Python C API exports from
+# RS274 Python/remap sources in src/emc/rs274ngc, including
+# interp_namedparams.cc, interp_o_word.cc, interp_python.cc, interp_remap.cc,
+# rs274ngc_pre.cc, and the py*/module binding sources.
 linuxcnc_root=${LINUXCNC_ROOT:-../linuxcnc}
 cxx=${CXX:-g++}
 if [[ -z ${CXX:-} ]] && command -v ccache >/dev/null 2>&1; then
diff --git a/test-linuxcnc-wasm-tooldata-runtime-symbols.sh b/test-linuxcnc-wasm-tooldata-runtime-symbols.sh
index 75b8459..7efd8bf 100755
--- a/test-linuxcnc-wasm-tooldata-runtime-symbols.sh
+++ b/test-linuxcnc-wasm-tooldata-runtime-symbols.sh
@@ -3,6 +3,9 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: this probe compares wasm-safe tooldata runtime stubs
+# against src/emc/tooldata/tooldata_db.cc and tooldata_nml.cc while excluding
+# exports already supplied by the wasm-safe tooldata_mmap backend.
 linuxcnc_root=${LINUXCNC_ROOT:-../linuxcnc}
 cxx=${CXX:-g++}
 if [[ -z ${CXX:-} ]] && command -v ccache >/dev/null 2>&1; then
diff --git a/test-native.sh b/test-native.sh
index cdd42aa..3bb88b7 100755
--- a/test-native.sh
+++ b/test-native.sh
@@ -51,6 +51,9 @@ if ! diff -u <(printf '%s\n' "$tooldata_source_entries") <(printf '%s\n' "$toold
 fi
 grep -F 'metadata:src/emc/tooldata/tooldata_db.cc:source basis for wasm-safe tooldata runtime export shim' linuxcnc-rs274-wasm-source-files.txt >/dev/null
 grep -F 'metadata:src/emc/tooldata/tooldata_nml.cc:source basis for wasm-safe tooldata runtime NML export shim' linuxcnc-rs274-wasm-source-files.txt >/dev/null
+grep -F 'LinuxCNC source basis: this probe derives required Python C API exports from' test-linuxcnc-wasm-python-c-api-symbols.sh >/dev/null
+grep -F 'LinuxCNC source basis: this probe compares wasm-safe tooldata runtime stubs' test-linuxcnc-wasm-tooldata-runtime-symbols.sh >/dev/null
+grep -F 'LinuxCNC source basis: the standalone probe links src/emc/rs274ngc/interp_base.cc' test-linuxcnc-wasm-interp-base-link.sh >/dev/null
 grep -F 'header:src/emc/ini/inifile.h:LinuxCNC C INI reader declarations exported by ini Submakefile' linuxcnc-rs274-wasm-source-files.txt >/dev/null
 grep -F 'header:src/emc/ini/inifile.hh:LinuxCNC C++ INI reader declarations used by inifile.cc' linuxcnc-rs274-wasm-source-files.txt >/dev/null
 grep -F 'metadata:src/emc/ini/Submakefile:LinuxCNC ini build metadata defining liblinuxcncini source and exported headers' linuxcnc-rs274-wasm-source-files.txt >/dev/null