diff --git a/src/lib/server/db/migrations/015_shopping_check_family.sql b/src/lib/server/db/migrations/015_shopping_check_family.sql
new file mode 100644
index 0000000..f396ba1
--- /dev/null
+++ b/src/lib/server/db/migrations/015_shopping_check_family.sql
@@ -0,0 +1,14 @@
+-- Konsolidierung: unit_key in shopping_cart_check wird zum Family-Key, damit
+-- Abhaks stabil bleiben wenn Display-Unit zwischen g und kg wechselt.
+-- g/kg → 'weight', ml/l → 'volume', Rest bleibt unveraendert.
+UPDATE shopping_cart_check SET unit_key = 'weight' WHERE LOWER(TRIM(unit_key)) IN ('g', 'kg');
+UPDATE shopping_cart_check SET unit_key = 'volume' WHERE LOWER(TRIM(unit_key)) IN ('ml', 'l');
+
+-- Nach Relabeling koennen Duplikate entstehen (zwei Zeilen mit 'weight' pro
+-- name_key). Juengsten Eintrag behalten.
+DELETE FROM shopping_cart_check
+WHERE rowid NOT IN (
+  SELECT MAX(rowid)
+  FROM shopping_cart_check
+  GROUP BY name_key, unit_key
+);