diff --git a/cli/cmd/auto.go b/cli/cmd/auto.go
index db33b20f..9ffef057 100644
--- a/cli/cmd/auto.go
+++ b/cli/cmd/auto.go
@@ -48,12 +48,14 @@ func init() {
 func runAuto(cmd *cobra.Command, args []string) error {
 	output.Header("Kates Auto-Deploy")
 
-	executor := detect.NewOSExecutor()
+	executor := defaultExecutor
 	collector := detect.NewCollector(executor)
+	// Introspection creates a namespace, a Secret and prober pods. A dry run
+	// collects without them, as kates deploy --dry-run does.
+	collector.ReadOnly = autoDryRun
 
 	if err := collector.Preflight(); err != nil {
-		output.Error(fmt.Sprintf("Preflight failed: %v", err))
-		os.Exit(1)
+		return cmdErr(fmt.Sprintf("Preflight failed: %v", err))
 	}
 
 	// 1. Detect Phase
@@ -62,6 +64,7 @@ func runAuto(cmd *cobra.Command, args []string) error {
 	report, collectErr := collector.Collect(context.Background())
 	if collectErr != nil {
 		output.Error(fmt.Sprintf("Cluster introspection failed: %v", collectErr))
+		// The CLI reference documents exit 2 here; an error from RunE exits 1.
 		os.Exit(2)
 	}
 
diff --git a/cli/cmd/auto_test.go b/cli/cmd/auto_test.go
new file mode 100644
index 00000000..13a7d5e3
--- /dev/null
+++ b/cli/cmd/auto_test.go
@@ -0,0 +1,40 @@
+package cmd
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// kates auto --dry-run introspected the cluster with every write probe on: a
+// namespace, a Secret and prober pods, where kates deploy --dry-run writes
+// nothing. The run without --dry-run is the control: the same introspection
+// does write.
+func TestAutoDryRunCollectsReadOnly(t *testing.T) {
+	origExecutor, origDryRun, origChart := defaultExecutor, autoDryRun, autoChartDir
+	t.Cleanup(func() { defaultExecutor, autoDryRun, autoChartDir = origExecutor, origDryRun, origChart })
+	// No chart there, so the run stops before helm, right after introspection.
+	autoChartDir = filepath.Join(t.TempDir(), "no-chart")
+
+	writes := func(dryRun bool) []string {
+		rec := &recordingExecutor{}
+		defaultExecutor, autoDryRun = rec, dryRun
+		if err := runAuto(autoCmd, nil); err == nil || !strings.Contains(err.Error(), "Helm chart not found") {
+			t.Fatalf("dry run %v: err = %v, want the missing chart", dryRun, err)
+		}
+		var out []string
+		for _, c := range rec.commands() {
+			if clusterWrite.MatchString(c) {
+				out = append(out, c)
+			}
+		}
+		return out
+	}
+
+	if len(writes(false)) == 0 {
+		t.Fatal("control: introspection without --dry-run wrote nothing, so the dry run proves nothing")
+	}
+	if got := writes(true); len(got) != 0 {
+		t.Errorf("auto --dry-run wrote to the cluster:\n  %s", strings.Join(got, "\n  "))
+	}
+}