Document and verify independent output destinations

internal/cli/config_input_test.go

@@ -215,6 +215,17 @@ func TestReportingAndDebugOverridesRemainIndependent(t *testing.T) {
 			t.Fatalf("%s did not honor explicit false: %+v", command, selected.Result.Config)
 		}
 	}
+	processInput, _, err := parseConfigInput("process", []string{"input.json", "--glossary", "glossary.yml", "--config", main, "--overlay", "testing"}, io.Discard)
+	if err != nil {
+		t.Fatal(err)
+	}
+	processConfig, err := loadConfigInput(processInput, "process")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, err := selectedReportDir(processConfig.Result.Config, filepath.Join("out", "corrected.json"), processInput.ReportDirSet); err != nil || got != "out" {
+		t.Fatalf("overlay stdout directory redirected file output: %q %v", got, err)
+	}
 }
 
 func TestReportDirectorySelectionOnlyUsesActiveDestination(t *testing.T) {