diff --git a/list-linuxcnc-bridge-smoke-project-sources.sh b/list-linuxcnc-bridge-smoke-project-sources.sh
index 6e9ff4f..c185ef5 100755
--- a/list-linuxcnc-bridge-smoke-project-sources.sh
+++ b/list-linuxcnc-bridge-smoke-project-sources.sh
@@ -3,6 +3,9 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: the bridge smoke source list is limited to the
+# canon bridge and kinematics adapters that wrap LinuxCNC canon.hh and
+# src/emc/kinematics behavior for native bridge checks.
 filter=${1:-}
 
 ./list-project-source-set.sh linuxcnc-bridge-smoke "$filter"
diff --git a/list-linuxcnc-rs274-api-project-sources.sh b/list-linuxcnc-rs274-api-project-sources.sh
index 05588ec..011f807 100755
--- a/list-linuxcnc-rs274-api-project-sources.sh
+++ b/list-linuxcnc-rs274-api-project-sources.sh
@@ -3,6 +3,9 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: the RS274 API source list combines CMake-listed core
+# bridge sources with linuxcnc_rs274_backend.cpp, which drives LinuxCNC
+# rs274ngc_pre.cc through the thin public C API.
 filter=${1:-}
 source_list=$(mktemp)
 trap 'rm -f "$source_list"' EXIT
diff --git a/list-linuxcnc-rs274-dump-project-sources.sh b/list-linuxcnc-rs274-dump-project-sources.sh
index 26a7218..7265d30 100755
--- a/list-linuxcnc-rs274-dump-project-sources.sh
+++ b/list-linuxcnc-rs274-dump-project-sources.sh
@@ -3,6 +3,9 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: the RS274 dump probe pairs LinuxCNC interpreter
+# sources with the canon bridge, tooldata fixture, and kinematics adapters
+# needed to serialize LinuxCNC-backed canonical events.
 filter=${1:-}
 
 ./list-project-source-set.sh linuxcnc-rs274-dump "$filter"
diff --git a/list-project-source-set.sh b/list-project-source-set.sh
index b0c2272..6dd432c 100755
--- a/list-project-source-set.sh
+++ b/list-project-source-set.sh
@@ -3,6 +3,10 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
+# LinuxCNC source basis: these project source sets are thin bridge/adaptor
+# objects used by LinuxCNC-backed native probes. They wrap canon.hh,
+# rs274ngc_pre.cc, tooldata.hh, and src/emc/kinematics sources instead of
+# providing independent G-code or kinematics behavior.
 if [[ "$#" -lt 1 || "$#" -gt 2 ]]; then
     echo "usage: $0 <source-set> [filter]" >&2
     exit 1
diff --git a/test-native.sh b/test-native.sh
index 79bd735..85d7d7a 100755
--- a/test-native.sh
+++ b/test-native.sh
@@ -74,6 +74,10 @@ grep -F 'grep -F '\''LinuxCNC source basis: src/emc/rs274ngc/rs274ngc_pre.cc pro
 grep -F 'core:src/emc/rs274ngc/rs274ngc_pre.cc:Interp implementation covered by rs274ngc_pre link probe' build-linuxcnc-wasm-standalone-probe.sh >/dev/null
 grep -F 'LinuxCNC source basis: fixed-source probes resolve explicit LinuxCNC-root' list-linuxcnc-source-files.sh >/dev/null
 grep -F 'LinuxCNC source path must be root-relative: $source' list-linuxcnc-source-files.sh >/dev/null
+grep -F 'LinuxCNC source basis: these project source sets are thin bridge/adaptor' list-project-source-set.sh >/dev/null
+grep -F 'LinuxCNC source basis: the RS274 dump probe pairs LinuxCNC interpreter' list-linuxcnc-rs274-dump-project-sources.sh >/dev/null
+grep -F 'LinuxCNC source basis: the bridge smoke source list is limited to the' list-linuxcnc-bridge-smoke-project-sources.sh >/dev/null
+grep -F 'LinuxCNC source basis: the RS274 API source list combines CMake-listed core' list-linuxcnc-rs274-api-project-sources.sh >/dev/null
 grep -F 'LinuxCNC source basis: manifest listers expose LinuxCNC-root relative source' list-linuxcnc-manifest-sources.sh >/dev/null
 grep -F 'manifest source must be LinuxCNC-root relative: $path' list-linuxcnc-manifest-sources.sh >/dev/null
 grep -F 'LinuxCNC source basis: linuxcnc-rs274-source-files.txt enumerates the native' list-linuxcnc-source-manifest-sources.sh >/dev/null