diff --git a/BACKLOG.md b/BACKLOG.md
index 2602966..e220cde 100644
--- a/BACKLOG.md
+++ b/BACKLOG.md
@@ -162,6 +162,21 @@ The base feature is shipped (entity, default seed on store create, list view gro
 - **Recipes → sections:** when pulling recipe ingredients into a list, map them to the list's store's sections (only meaningful once the per-store ingredient memory or product catalog lands).
 - **Section drag-to-reorder** in the store edit UI — section walk order matters, but reordering today only works by editing `SortOrder` numbers manually.
 
+### Auto-assign section from product
+When a user picks a product from the typeahead on the shopping list add form, pre-populate the section dropdown with that product's known section for the current store — rather than leaving it as "Uncategorized".
+
+This is the "per-store ingredient memory" item above, stated from the user's perspective: choosing "Spaghetti" should already know it belongs in Pasta/Dry Goods at this store.
+
+**Data model:** `ProductStoreSection` is already sketched in the product catalog section above — `(FamilyId, ProductId | FamilyProductId, StoreId, StoreSectionId)`. That table is the source of truth.
+
+**Write path:** when a user manually changes the section on a list item whose product is linked, offer to remember that choice (or auto-remember silently after N uses). Write to `ProductStoreSection`.
+
+**Read path:** on product selection in the add-item form, query the effective section for `(productId, storeId)` and pre-select it in the section dropdown. User can still override.
+
+**Dependencies:** requires the product catalog entity to be in place (`ProductId` on `ShoppingListItem`, product typeahead already wired). The `ProductStoreSection` table and its endpoints are net-new work.
+
+**Scope note:** the section pre-fill should be scoped to the family's own memory (`ProductStoreSection` rows they've created), not a global default — different families organize differently.
+
 ## Lists
 
 ### Block create-list flow when no stores exist