diff --git a/src/game/engine/src/entities/city.gd b/src/game/engine/src/entities/city.gd
index bda894ec..9027cbb7 100644
--- a/src/game/engine/src/entities/city.gd
+++ b/src/game/engine/src/entities/city.gd
@@ -99,6 +99,35 @@ func _init(city_id: String = "", starting_buildings: Array[String] = []) -> void
 		for b in buildings:
 			b_arr.push_back(b)
 		_gd_city.call("initialize", id, b_arr)
+		for b in buildings:
+			_register_building_yields(b)
+
+
+## Register flat yield bonuses for a building id by reading its JSON `effects`.
+## Called on starting buildings in `_init` and after `add_building` so the
+## Rust City.get_yields applies e.g. monument +2 culture.
+func _register_building_yields(building_id: String) -> void:
+	if _gd_city == null:
+		return
+	var def: Dictionary = DataLoader.get_building(building_id)
+	if def.is_empty():
+		return
+	var food: float = 0.0
+	var production: float = 0.0
+	var gold: float = 0.0
+	var culture: float = 0.0
+	var science: float = 0.0
+	for effect: Dictionary in def.get("effects", []):
+		var value: float = float(effect.get("value", 0))
+		match effect.get("type", ""):
+			"food": food += value
+			"production": production += value
+			"gold": gold += value
+			"culture": culture += value
+			"science": science += value
+	_gd_city.call(
+		"register_building_yields", building_id, food, production, gold, culture, science
+	)
 
 
 # ── Founding ────────────────────────────────────────────────────────
@@ -381,6 +410,7 @@ func add_building(building: String) -> void:
 	buildings.append(building)
 	if _gd_city != null:
 		_gd_city.call("add_building", building)
+		_register_building_yields(building)
 
 
 func has_building(building: String) -> bool: