feat: define authoritative action effects

simulation/definitions/ContentCatalog.gd

@@ -92,7 +92,9 @@ func rebuild(
 					)
 				)
 
-	_validate_action_references(actions, actions_by_id, professions_by_id, items_by_id, errors)
+	_validate_action_references(
+		actions, actions_by_id, professions_by_id, items_by_id, supported_handlers, errors
+	)
 	_validate_enemy_references(enemies, items_by_id, errors)
 	errors.sort()
 	_errors = errors
@@ -249,9 +251,23 @@ static func _validate_action_references(
 	actions_by_id: Dictionary,
 	professions_by_id: Dictionary,
 	items_by_id: Dictionary,
+	supported_handlers: Dictionary,
 	errors: Array[String]
 ) -> void:
 	for definition in actions:
+		for handler_field in [
+			["selection policy", definition.selection_policy_id],
+			["target policy", definition.target_policy_id],
+			["completion handler", definition.completion_handler_id],
+		]:
+			var handler_id: StringName = handler_field[1]
+			if not handler_id.is_empty() and not supported_handlers.has(handler_id):
+				errors.append(
+					(
+						"Action '%s' references unknown %s '%s'"
+						% [definition.action_id, handler_field[0], handler_id]
+					)
+				)
 		if (
 			not definition.preferred_profession_id.is_empty()
 			and not professions_by_id.has(definition.preferred_profession_id)