diff --git a/cmd/root.go b/cmd/root.go
index 9750d9bf6fc1c3b471408996482347a7c195779d..1cae4d1c4c20d50e0e474f5fff1e3b9a759574ad 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -44,6 +44,11 @@ var rootCmd = &cobra.Command{
 	TraverseChildren: true,
 
 	RunE: func(cmd *cobra.Command, _ []string) error {
+		// Bare keld with no subcommand requires a tty.
+		if !isInteractive() {
+			return fmt.Errorf("keld: no subcommand specified; non-interactive mode requires a subcommand (e.g. 'keld backup')")
+		}
+
 		commandName, preset, overrides, err := runInteractive("")
 		if err != nil {
 			return err
diff --git a/cmd/root_noninteractive_test.go b/cmd/root_noninteractive_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..dc2409e22b120d559635870cfb2feaccdb533e63
--- /dev/null
+++ b/cmd/root_noninteractive_test.go
@@ -0,0 +1,38 @@
+package cmd
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestRootRunNonInteractiveRequiresSubcommand(t *testing.T) {
+	// Not parallel: mutates package-level isStdinTerminal.
+
+	// Override stdin terminal check to simulate non-interactive environment.
+	original := isStdinTerminal
+	t.Cleanup(func() {
+		isStdinTerminal = original
+	})
+	isStdinTerminal = func() bool { return false }
+
+	// Reset root command flags to defaults.
+	setRootFlagValuesForTest(t, "", false, "")
+	t.Setenv("KELD_CONFIG_FILE", "")
+	t.Setenv("KELD_DRYRUN", "")
+
+	err := rootCmd.RunE(rootCmd, nil)
+	if err == nil {
+		t.Fatal("expected error for bare keld in non-interactive mode, got nil")
+	}
+
+	errMsg := err.Error()
+	// Should NOT be a bubbletea TTY error.
+	if strings.Contains(errMsg, "bubbletea") || strings.Contains(errMsg, "TTY") {
+		t.Fatalf("non-interactive mode incorrectly tried to open TTY: %v", err)
+	}
+
+	// Should mention missing subcommand.
+	if !strings.Contains(errMsg, "subcommand") {
+		t.Fatalf("expected error to mention subcommand, got: %v", err)
+	}
+}
\ No newline at end of file