WIP checkpoint: Address review feedback: Fix: navigating Play -> Back logs the user out (should stay logged in)

scripts/smoke_test_main_menu_back.gd

@@ -14,7 +14,7 @@ extends SceneTree
 ##   3. Click Play -> world_list.tscn.
 ##   4. Click Back -> main_menu.tscn.
 ##   5. Assert the menu is STILL authenticated (Play enabled, welcome label
-##      visible, login/register buttons hidden).
+##      actually visible in the tree, login/register buttons hidden).
 ##
 ## Run with:
 ##     godot --headless --path . --script res://scripts/smoke_test_main_menu_back.gd
@@ -118,14 +118,18 @@ func _is_authenticated(menu: Control) -> bool:
 	var auth_panel: PanelContainer = menu.get_node("CenterContainer/VBoxContainer/AuthPanel")
 
 	_check("Play enabled", not play_button.disabled)
-	_check("Welcome label visible", welcome_label.visible)
+	# WelcomeLabel lives inside AuthPanel, so `.visible` alone is a
+	# false-positive: the label can have visible=true while its parent is
+	# hidden and it renders as nothing. `is_visible_in_tree()` is the
+	# check that proves the user can actually see the welcome message.
+	_check("Welcome label visible in tree", welcome_label.is_visible_in_tree())
 	_check("Auth buttons row hidden", not auth_buttons_row.visible)
-	_check("Auth panel hidden", not auth_panel.visible)
+	_check("Auth panel visible (it contains the welcome label)", auth_panel.visible)
 
 	return (not play_button.disabled) \
-		and welcome_label.visible \
+		and welcome_label.is_visible_in_tree() \
 		and not auth_buttons_row.visible \
-		and not auth_panel.visible
+		and auth_panel.visible
 
 
 func _wait_for_scene_change(previous_scene: Node) -> void: