fix(core/tree): handle regression on tab_bar.hide_when=single_tab; ad…

…d test

src/qtile_bonsai/core/tree.py

@@ -782,6 +782,8 @@ def _add_tab(
                 "must be provided."
             )
 
+        self._ensure_tab_bar_restored(tc)
+
         tc_rect = Rect.from_rect(tc.principal_rect) if tc_rect is None else tc_rect
         bar_rect = tc.tab_bar.box.principal_rect
         tc_content_rect = Rect(
@@ -795,8 +797,6 @@ def _transform_tab(t: Tab):
 
         added_nodes = []
 
-        self._ensure_tab_bar_restored(tc)
-
         # Handle the need for a T under the TC
         if isinstance(insert_node, Tab):
             t = insert_node

tests/unit/core/test_tree.py

@@ -4058,6 +4058,22 @@ def test_padding_with_list(self, tree: Tree):
             assert tc1.tab_bar.box.padding.as_list() == [1, 2, 3, 4]
             assert tc2.tab_bar.box.padding.as_list() == [5, 6, 7, 8]
 
+        def test_when_hide_when_is_single_tab_then_first_tab_should_have_bar_hidden_and_second_tab_should_make_it_visible(
+            self, tree: Tree
+        ):
+            tree.set_config("tab_bar.hide_when", "single_tab")
+
+            p1 = tree.tab()
+
+            # bar should not be consuming space
+            assert p1.principal_rect == Rect(0, 0, 400, 300)
+
+            p2 = tree.tab()
+
+            # bar should now be taking up space
+            assert p1.principal_rect == Rect(0, 20, 400, 280)
+            assert p2.principal_rect == Rect(0, 20, 400, 280)
+
 
 class TestIterWalk:
     def test_new_tree_instance_has_no_nodes(self, tree: Tree):