diff --git a/cmd/drover/main.go b/cmd/drover/main.go
index 4987245..748582f 100644
--- a/cmd/drover/main.go
+++ b/cmd/drover/main.go
@@ -39,6 +39,13 @@ func newRootCmd() *cobra.Command {
 		Version:       fmt.Sprintf("%s (commit %s, built %s)", Version, Commit, BuildDate),
 		SilenceUsage:  true,
 		SilenceErrors: false,
+		// No subcommand and no flags = end-user double-clicked the exe;
+		// open the smoke-test window instead of dumping CLI help to a
+		// console they didn't ask for.
+		RunE: func(cmd *cobra.Command, args []string) error {
+			showTestWindow()
+			return nil
+		},
 	}
 
 	// Custom version template: "drover-go vX.Y.Z (commit abc1234, built 2026-05-01)".