diff --git a/internal/config/zz_ci_probe_test.go b/internal/config/zz_ci_probe_test.go
new file mode 100644
index 0000000..5c59e72
--- /dev/null
+++ b/internal/config/zz_ci_probe_test.go
@@ -0,0 +1,10 @@
+package config_test
+
+import "testing"
+
+// TestCIProbe126 is a deliberately failing test used to determine whether CI
+// executes the real gate for this repository. It lives only on the throwaway
+// branch ci-probe-126 and must never be merged.
+func TestCIProbe126(t *testing.T) {
+	t.Fatal("CI-PROBE-126: planted failure; if CI reports success this gate did not run")
+}