ALTER TABLE piece_usages ADD COLUMN preparation_status_snapshot TEXT NOT NULL DEFAULT 'ready'
	CHECK (preparation_status_snapshot IN ('preparing', 'ready'));

ALTER TABLE piece_usages ADD COLUMN preparation_effort_snapshot TEXT
	CHECK (preparation_effort_snapshot IS NULL OR preparation_effort_snapshot IN ('low', 'medium', 'high'));

UPDATE piece_usages
SET preparation_status_snapshot = CASE
		WHEN EXISTS (
			SELECT 1 FROM pieces p
			WHERE p.id = piece_usages.original_piece_id AND p.status = 'preparing'
		) THEN 'preparing'
		ELSE 'ready'
	END,
	preparation_effort_snapshot = (
		SELECT p.preparation_effort FROM pieces p WHERE p.id = piece_usages.original_piece_id
	);