perf(sdui): cache visible row list and eliminate rows.any linear scan in SduiTreeBuilder

lib/features/connections/sdui_tree_builder.dart

@@ -65,6 +65,10 @@ class SduiTreeBuilderState extends material.State<SduiTreeBuilder> {
   final Set<String> _loaded = {};
   final Set<String> _expanded = {};
   final Map<String, String> _expandErrors = {};
+  List<_VisibleRow>? _cachedVisibleRows;
+
+  @material.visibleForTesting
+  List<Object?>? get debugVisibleRows => _cachedVisibleRows;
 
   static const double _rowExtent = 28;
 
@@ -83,13 +87,15 @@ class SduiTreeBuilderState extends material.State<SduiTreeBuilder> {
       _loaded.clear();
       _expanded.clear();
       _expandErrors.clear();
+      _cachedVisibleRows = null;
     }
   }
 
   Future<void> _onExpand(SduiTreeNode node) async {
     setState(() {
       _expanded.add(node.id);
       _expandErrors.remove(node.id);
+      _cachedVisibleRows = null;
     });
     if (!node.expandable || _loaded.contains(node.id) || node.hasChildren) {
       return;
@@ -112,18 +118,23 @@ class SduiTreeBuilderState extends material.State<SduiTreeBuilder> {
         if (children.isEmpty) {
           _expandErrors[node.id] = 'No child objects found.';
         }
+        _cachedVisibleRows = null;
       });
     } catch (e) {
       if (!mounted) return;
       setState(() {
         _loading.remove(node.id);
         _expandErrors[node.id] = e.toString();
+        _cachedVisibleRows = null;
       });
     }
   }
 
   void _onCollapse(SduiTreeNode node) {
-    setState(() => _expanded.remove(node.id));
+    setState(() {
+      _expanded.remove(node.id);
+      _cachedVisibleRows = null;
+    });
   }
 
   void _toggleExpand(SduiTreeNode node) {
@@ -143,6 +154,7 @@ class SduiTreeBuilderState extends material.State<SduiTreeBuilder> {
         node.id,
         (n) => n.copyWith(children: const []),
       );
+      _cachedVisibleRows = null;
     });
     await _onExpand(node);
   }
@@ -185,13 +197,13 @@ class SduiTreeBuilderState extends material.State<SduiTreeBuilder> {
 
   @override
   material.Widget build(material.BuildContext context) {
-    final rows = _flattenVisible();
+    final rows = _cachedVisibleRows ??= _flattenVisible();
     final list = material.ListView.builder(
       shrinkWrap: widget.maxHeight == null,
       physics: widget.maxHeight == null
           ? const material.NeverScrollableScrollPhysics()
           : const material.ClampingScrollPhysics(),
-      itemExtent: rows.any((r) => r.isError) ? null : _rowExtent,
+      itemExtent: _expandErrors.isNotEmpty ? null : _rowExtent,
       itemCount: rows.length,
       itemBuilder: (context, index) {
         final row = rows[index];

test/core/sdui/sdui_builders_test.dart

@@ -518,5 +518,67 @@ void main() {
       final text = tester.widget<material.Text>(find.text('users'));
       expect(text.style?.fontWeight, isNot(material.FontWeight.w600));
     });
+
+    testWidgets(
+        'caches visible rows and preserves itemExtent without scanning list on selection changes',
+        (tester) async {
+      final schema = SduiTreeSchema.fromJson(const {
+        'roots': [
+          {
+            'id': 'folder.tables',
+            'label': 'Tables',
+            'expandable': true,
+            'children': [
+              {
+                'id': 'table.users',
+                'label': 'users',
+                'node_type': 'table',
+              },
+            ],
+          },
+        ],
+      });
+
+      var selected = 'table.users';
+      late material.StateSetter parentSetState;
+
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.StatefulBuilder(
+            builder: (context, setState) {
+              parentSetState = setState;
+              return material.Scaffold(
+                body: SduiTreeBuilder(
+                  schema: schema,
+                  selectedNodeId: selected,
+                ),
+              );
+            },
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      final state = tester.state<SduiTreeBuilderState>(
+        find.byType(SduiTreeBuilder),
+      );
+      final initialRows = state.debugVisibleRows;
+      expect(initialRows, isNotNull);
+      expect(initialRows!.length, 1);
+
+      // Verify itemExtent is set to 28 when there are no errors
+      final listView = tester.widget<material.ListView>(
+        find.byType(material.ListView),
+      );
+      expect(listView.itemExtent, 28);
+
+      // Change selection in parent: rebuilds SduiTreeBuilder without changing roots/expansion
+      parentSetState(() => selected = 'other');
+      await tester.pump();
+
+      // Cached rows must be reused by identity
+      expect(state.debugVisibleRows, same(initialRows));
+    });
   });
 }
+