diff --git a/src/game/engine/scenes/tests/full_game_demo_proof.gd b/src/game/engine/scenes/tests/full_game_demo_proof.gd
index 77aebdd6..c78bada6 100644
--- a/src/game/engine/scenes/tests/full_game_demo_proof.gd
+++ b/src/game/engine/scenes/tests/full_game_demo_proof.gd
@@ -94,23 +94,25 @@ func _ready() -> void:
 	var empty_fog: Array[Vector2i] = []
 	hex.update_fog(all_positions, empty_fog)
 
+	# Aggregate every player's units / cities and feed them into the
+	# renderers via their canonical sync_* surfaces.
+	var all_units: Array = []
+	var all_cities: Array = []
+	for p: Variant in GameState.players:
+		if p is PlayerScript:
+			all_units.append_array((p as PlayerScript).units)
+			all_cities.append_array((p as PlayerScript).cities)
+
 	var units: Node2D = UnitRendererScript.new()
 	units.name = "UnitRenderer"
 	add_child(units)
-	if units.has_method("setup_visibility"):
-		units.call("setup_visibility", 0, game_map)
-	if units.has_method("render_units"):
-		units.call("render_units", game_map)
-	elif units.has_method("refresh"):
-		units.call("refresh")
+	units.call("setup_visibility", 0, game_map)
+	units.call("sync_units", all_units)
 
 	var cities: Node2D = CityRendererScript.new()
 	cities.name = "CityRenderer"
 	add_child(cities)
-	if cities.has_method("refresh"):
-		cities.call("refresh")
-	elif cities.has_method("render_cities"):
-		cities.call("render_cities")
+	cities.call("sync_cities", all_cities)
 
 	# Camera centred on the actual pixel-bbox of the rendered tiles. The
 	# axial→pixel transform isn't a simple linear scale (flat-top hex offset