fix(doris): preserve single external catalog visibility

apps/desktop/src/lib/database/databaseFeatureSupport.ts

@@ -1,4 +1,4 @@
-import type { ConnectionConfig, DatabaseType, TreeNodeType } from "@/types/database";
+import type { CatalogInfo, ConnectionConfig, DatabaseType, TreeNodeType } from "@/types/database";
 import { supportsDatabaseFeature } from "@/lib/database/databaseDriverManifest";
 import { canEditTableStructure } from "@/lib/table/tableStructureCapabilities";
 import { CLEARABLE_QUERY_SCHEMA_TYPES, DATABASE_OBJECT_TREE_TYPES, DATABASE_SCHEMA_QUALIFIED_TYPES, FETCH_FIRST_TYPES, PG_LIKE_STRUCTURE_TYPES, PG_VACUUM_TYPES, SCHEMA_AWARE_TYPES, SINGLE_DATABASE_TYPES, TREE_SCHEMA_TYPES } from "@/lib/database/databaseCapabilitySets";
@@ -45,6 +45,15 @@ export function isInternalDorisCatalog(catalogType?: string | null, catalogName?
   return (catalogName ?? "").trim() === "internal";
 }
 
+/**
+ * Keep the catalog grouping layer whenever SHOW CATALOGS exposes an external
+ * catalog. A single visible external catalog still carries namespace
+ * information that cannot be represented by the flat database tree.
+ */
+export function shouldShowDorisCatalogTree(catalogs: readonly CatalogInfo[]): boolean {
+  return catalogs.some((catalog) => !isInternalDorisCatalog(catalog.catalog_type, catalog.name));
+}
+
 export function usesTreeSchemaMode(dbType?: DatabaseType): boolean {
   return !!dbType && TREE_SCHEMA_TYPES.has(dbType);
 }