Section defaults on products with prompt-on-divergence

- Add DefaultSection (string?) to Product, FamilyProduct, and
  FamilyProductOverride. Resolution order on item add: per-store memory
  (ProductStoreSection) → family default (override or family product) →
  global product default, matched case-insensitively by name to the
  current store''s StoreSection rows.
- Drop the section dropdown from the add-item form; the backend resolves
  on POST. Section change on a list row syncs the family default:
  silently creates it when none exists, no-op when it matches, returns
  promptSaveDefault=true when it differs so the client confirms before
  updating.
- Expose DefaultSection on the catalog page form. Replace the native
  datalist with a styled TextCombobox component for autocomplete
  suggestions (seeded from typicalSections) while still allowing
  free-text entry. Pattern doc-noted as the sibling of ProductTypeahead.
- Remove the now-unused GET /api/products/{kind}/{id}/section endpoint
  and its tests; the add-form pre-fill they backed is gone.

src/backend/YesChef.Api.IntegrationTests/Features/ProductEndpointsTests.cs

@@ -1,6 +1,5 @@
 using System.Net;
 using System.Net.Http.Json;
-using System.Text.Json;
 using YesChef.Api.Entities;
 using YesChef.Api.Features.Products;
 using YesChef.Api.IntegrationTests.Infrastructure;
@@ -365,130 +364,94 @@ public class ProductEndpointsTests : AuthenticatedIntegrationTest
     }
 
     [Test]
-    public async Task Get_global_product_section_returns_remembered_section()
+    public async Task Create_family_product_persists_default_section()
     {
-        var familyId = await GetFamilyIdAsync();
-        var store = await Data.CreateStoreAsync();
-        var (product, section) = await UseDbAsync(async db =>
-        {
-            var p = new Product { Name = "Bananas-Lookup" };
-            var s = new StoreSection { FamilyId = familyId, StoreId = store.Id, Name = "Produce", SortOrder = 1 };
-            db.Products.Add(p);
-            db.StoreSections.Add(s);
-            await db.SaveChangesAsync();
-            db.ProductStoreSections.Add(new ProductStoreSection
-            {
-                FamilyId = familyId,
-                StoreId = store.Id,
-                ProductId = p.Id,
-                StoreSectionId = s.Id,
-            });
-            await db.SaveChangesAsync();
-            return (p, s);
-        });
+        var response = await Client.PostAsJsonAsync("/api/products",
+            new ProductEndpoints.CreateProductRequest("Sourdough", null, null, UnitCategoryFlags.None, "  Bakery  "));
 
-        var body = await Client.GetFromJsonAsync<JsonElement>(
-            $"/api/products/global/{product.Id}/section?storeId={store.Id}");
+        await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.Created);
+        var dto = await response.Content.ReadFromJsonAsync<ProductEndpoints.ProductDto>();
+        await Assert.That(dto!.DefaultSection).IsEqualTo("Bakery");
 
-        await Assert.That(body.GetProperty("sectionId").GetInt32()).IsEqualTo(section.Id);
+        var stored = await UseDbAsync(db => db.FamilyProducts.SingleAsync());
+        await Assert.That(stored.DefaultSection).IsEqualTo("Bakery");
     }
 
     [Test]
-    public async Task Get_global_product_section_returns_null_when_no_memory()
+    public async Task Update_family_product_clears_default_section_when_blank()
     {
-        var store = await Data.CreateStoreAsync();
+        var familyId = await GetFamilyIdAsync();
         var product = await UseDbAsync(async db =>
         {
-            var p = new Product { Name = "Unknown-Lookup" };
+            var p = new FamilyProduct { FamilyId = familyId, Name = "Flour", DefaultSection = "Pantry" };
+            db.FamilyProducts.Add(p);
+            await db.SaveChangesAsync();
+            return p;
+        });
+
+        var response = await Client.PutAsJsonAsync($"/api/products/family/{product.Id}",
+            new ProductEndpoints.UpdateProductRequest(null, null, null, null, "   "));
+        await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.OK);
+
+        var refreshed = await UseDbAsync(db => db.FamilyProducts.SingleAsync(p => p.Id == product.Id));
+        await Assert.That(refreshed.DefaultSection).IsNull();
+    }
+
+    [Test]
+    public async Task Update_global_product_writes_default_section_to_override()
+    {
+        var familyId = await GetFamilyIdAsync();
+        var product = await UseDbAsync(async db =>
+        {
+            var p = new Product { Name = "Bananas", DefaultSection = "Produce" };
             db.Products.Add(p);
             await db.SaveChangesAsync();
             return p;
         });
 
-        var body = await Client.GetFromJsonAsync<JsonElement>(
-            $"/api/products/global/{product.Id}/section?storeId={store.Id}");
+        var response = await Client.PutAsJsonAsync($"/api/products/global/{product.Id}",
+            new ProductEndpoints.UpdateProductRequest(null, null, null, null, "Frozen"));
+        await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.OK);
+        var dto = await response.Content.ReadFromJsonAsync<ProductEndpoints.ProductDto>();
+        await Assert.That(dto!.DefaultSection).IsEqualTo("Frozen");
 
-        await Assert.That(body.GetProperty("sectionId").ValueKind).IsEqualTo(JsonValueKind.Null);
+        // Global row untouched.
+        var global = await UseDbAsync(db => db.Products.SingleAsync(p => p.Id == product.Id));
+        await Assert.That(global.DefaultSection).IsEqualTo("Produce");
+
+        var ovr = await UseDbAsync(db => db.FamilyProductOverrides
+            .SingleAsync(o => o.FamilyId == familyId && o.ProductId == product.Id));
+        await Assert.That(ovr.DefaultSection).IsEqualTo("Frozen");
     }
 
     [Test]
-    public async Task Get_global_product_section_is_scoped_to_store()
+    public async Task Search_projects_effective_default_section()
     {
         var familyId = await GetFamilyIdAsync();
-        var storeA = await Data.CreateStoreAsync(b => b.Named("A"));
-        var storeB = await Data.CreateStoreAsync(b => b.Named("B"));
-        var product = await UseDbAsync(async db =>
+        await UseDbAsync(async db =>
         {
-            var p = new Product { Name = "Apples-Lookup" };
-            var sectionA = new StoreSection { FamilyId = familyId, StoreId = storeA.Id, Name = "Produce A", SortOrder = 1 };
-            db.Products.Add(p);
-            db.StoreSections.Add(sectionA);
+            db.Products.Add(new Product { Name = "Apples", DefaultSection = "Produce" });
+            db.Products.Add(new Product { Name = "Berries", DefaultSection = "Produce" });
             await db.SaveChangesAsync();
-            db.ProductStoreSections.Add(new ProductStoreSection
+            var berries = db.Products.Single(p => p.Name == "Berries");
+            db.FamilyProductOverrides.Add(new YesChef.Api.Entities.FamilyProductOverride
             {
                 FamilyId = familyId,
-                StoreId = storeA.Id,
-                ProductId = p.Id,
-                StoreSectionId = sectionA.Id,
+                ProductId = berries.Id,
+                DefaultSection = "Frozen",
             });
-            await db.SaveChangesAsync();
-            return p;
-        });
-
-        // Lookup at store B — no memory there even though store A has one.
-        var body = await Client.GetFromJsonAsync<JsonElement>(
-            $"/api/products/global/{product.Id}/section?storeId={storeB.Id}");
-
-        await Assert.That(body.GetProperty("sectionId").ValueKind).IsEqualTo(JsonValueKind.Null);
-    }
-
-    [Test]
-    public async Task Get_family_product_section_returns_remembered_section()
-    {
-        var familyId = await GetFamilyIdAsync();
-        var store = await Data.CreateStoreAsync();
-        var (product, section) = await UseDbAsync(async db =>
-        {
-            var p = new FamilyProduct { FamilyId = familyId, Name = "House Bread" };
-            var s = new StoreSection { FamilyId = familyId, StoreId = store.Id, Name = "Bakery", SortOrder = 1 };
-            db.FamilyProducts.Add(p);
-            db.StoreSections.Add(s);
-            await db.SaveChangesAsync();
-            db.ProductStoreSections.Add(new ProductStoreSection
+            db.FamilyProducts.Add(new FamilyProduct
             {
                 FamilyId = familyId,
-                StoreId = store.Id,
-                FamilyProductId = p.Id,
-                StoreSectionId = s.Id,
+                Name = "House Bread",
+                DefaultSection = "Bakery",
             });
             await db.SaveChangesAsync();
-            return (p, s);
         });
 
-        var body = await Client.GetFromJsonAsync<JsonElement>(
-            $"/api/products/family/{product.Id}/section?storeId={store.Id}");
-
-        await Assert.That(body.GetProperty("sectionId").GetInt32()).IsEqualTo(section.Id);
-    }
-
-    [Test]
-    public async Task Get_family_product_section_returns_404_for_other_family_product()
-    {
-        var store = await Data.CreateStoreAsync();
-        var otherFamilyProductId = await UseDbAsync(async db =>
-        {
-            var otherFamily = new Family { Name = "Other", InviteCode = "other-code" };
-            db.Families.Add(otherFamily);
-            await db.SaveChangesAsync();
-            var p = new FamilyProduct { FamilyId = otherFamily.Id, Name = "Their Bread" };
-            db.FamilyProducts.Add(p);
-            await db.SaveChangesAsync();
-            return p.Id;
-        });
-
-        var response = await Client.GetAsync(
-            $"/api/products/family/{otherFamilyProductId}/section?storeId={store.Id}");
-
-        await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.NotFound);
+        var results = (await Client.GetFromJsonAsync<List<ProductEndpoints.ProductDto>>("/api/products?q="))!;
+        await Assert.That(results.Single(r => r.Name == "Apples").DefaultSection).IsEqualTo("Produce");
+        await Assert.That(results.Single(r => r.Name == "Berries").DefaultSection).IsEqualTo("Frozen");
+        await Assert.That(results.Single(r => r.Name == "House Bread").DefaultSection).IsEqualTo("Bakery");
     }
 }

src/backend/YesChef.Api.IntegrationTests/Features/ShoppingListEndpointsTests.cs

@@ -207,10 +207,10 @@ public class ShoppingListEndpointsTests : AuthenticatedIntegrationTest
     }
 
     [Test]
-    public async Task Add_item_records_section_memory_and_auto_assigns_on_next_add()
+    public async Task Add_item_resolves_section_from_global_product_default()
     {
         var list = await CreateListAsync();
-        var section = await UseDbAsync(async db =>
+        var produce = await UseDbAsync(async db =>
         {
             var s = new StoreSection { FamilyId = Store.FamilyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
             db.StoreSections.Add(s);
@@ -219,99 +219,312 @@ public class ShoppingListEndpointsTests : AuthenticatedIntegrationTest
         });
         var product = await UseDbAsync(async db =>
         {
-            var p = new Product { Name = "Bananas-Memory" };
+            var p = new Product { Name = "Bananas-Default", DefaultSection = "Produce" };
             db.Products.Add(p);
             await db.SaveChangesAsync();
             return p;
         });
 
-        // First add: explicit section + product → memory recorded.
-        var first = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
-            new ShoppingListEndpoints.AddItemRequest("Bananas", SectionId: section.Id, ProductId: product.Id));
-        await Assert.That(first.StatusCode).IsEqualTo(HttpStatusCode.Created);
+        var response = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
+            new ShoppingListEndpoints.AddItemRequest("Bananas", ProductId: product.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
 
-        // Second add: same product, no section → auto-assigned from memory.
-        var second = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
-            new ShoppingListEndpoints.AddItemRequest("More Bananas", ProductId: product.Id));
-        await Assert.That(second.StatusCode).IsEqualTo(HttpStatusCode.Created);
-
-        var items = await UseDbAsync(db => db.ShoppingListItems
-            .Where(i => i.ShoppingListId == list.Id).OrderBy(i => i.Id).ToListAsync());
-        await Assert.That(items.Count).IsEqualTo(2);
-        await Assert.That(items[1].SectionId).IsEqualTo(section.Id);
+        await Assert.That(body.GetProperty("sectionId").GetInt32()).IsEqualTo(produce.Id);
     }
 
     [Test]
-    public async Task Patch_item_section_updates_memory_for_next_add()
+    public async Task Add_item_resolves_section_with_case_insensitive_name_match()
     {
         var list = await CreateListAsync();
-        var (originalSection, correctedSection) = await UseDbAsync(async db =>
+        var produce = await UseDbAsync(async db =>
         {
-            var s1 = new StoreSection { FamilyId = Store.FamilyId, StoreId = Store.Id, Name = "Pantry", SortOrder = 1 };
-            var s2 = new StoreSection { FamilyId = Store.FamilyId, StoreId = Store.Id, Name = "Bakery", SortOrder = 2 };
-            db.StoreSections.AddRange(s1, s2);
+            var s = new StoreSection { FamilyId = Store.FamilyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            db.StoreSections.Add(s);
             await db.SaveChangesAsync();
-            return (s1, s2);
+            return s;
         });
         var product = await UseDbAsync(async db =>
         {
-            var p = new Product { Name = "Bread-Memory" };
+            var p = new Product { Name = "Bananas-Case", DefaultSection = "  produce  " };
             db.Products.Add(p);
             await db.SaveChangesAsync();
             return p;
         });
 
-        // Add with section A; that records (Product → A) memory.
-        var addResponse = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
-            new ShoppingListEndpoints.AddItemRequest("Bread", SectionId: originalSection.Id, ProductId: product.Id));
-        var addBody = await addResponse.Content.ReadFromJsonAsync<JsonElement>();
-        var firstItemId = addBody.GetProperty("id").GetInt32();
+        var response = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
+            new ShoppingListEndpoints.AddItemRequest("Bananas", ProductId: product.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
 
-        // User corrects to section B → memory should update.
-        var patchResponse = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{firstItemId}/section",
-            new ShoppingListEndpoints.SetItemSectionRequest(correctedSection.Id));
-        await Assert.That(patchResponse.StatusCode).IsEqualTo(HttpStatusCode.OK);
-
-        // Next add (no section) should now pull section B.
-        var second = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
-            new ShoppingListEndpoints.AddItemRequest("More Bread", ProductId: product.Id));
-        var secondBody = await second.Content.ReadFromJsonAsync<JsonElement>();
-        await Assert.That(secondBody.GetProperty("sectionId").GetInt32()).IsEqualTo(correctedSection.Id);
+        await Assert.That(body.GetProperty("sectionId").GetInt32()).IsEqualTo(produce.Id);
     }
 
     [Test]
-    public async Task Section_memory_is_scoped_per_store()
+    public async Task Add_item_resolves_to_null_when_default_section_does_not_exist_in_store()
     {
-        var listA = await CreateListAsync();
-        var otherStore = await Data.CreateStoreAsync(b => b.Named("Other Store"));
-        var listB = await Data.CreateListAsync(b => b.ForStore(otherStore).CreatedBy(User));
-        var (sectionA, sectionB) = await UseDbAsync(async db =>
-        {
-            var a = new StoreSection { FamilyId = Store.FamilyId, StoreId = Store.Id, Name = "Produce A", SortOrder = 1 };
-            var b = new StoreSection { FamilyId = otherStore.FamilyId, StoreId = otherStore.Id, Name = "Produce B", SortOrder = 1 };
-            db.StoreSections.AddRange(a, b);
-            await db.SaveChangesAsync();
-            return (a, b);
-        });
+        var list = await CreateListAsync();
         var product = await UseDbAsync(async db =>
         {
-            var p = new Product { Name = "Apples-Memory" };
+            var p = new Product { Name = "Imports-Only", DefaultSection = "Specialty" };
             db.Products.Add(p);
             await db.SaveChangesAsync();
             return p;
         });
 
-        // Memorize at store A only.
-        await Client.PostAsJsonAsync($"/api/lists/{listA.Id}/items",
-            new ShoppingListEndpoints.AddItemRequest("Apples", SectionId: sectionA.Id, ProductId: product.Id));
-
-        // Add at store B with no section → no memory yet for store B.
-        var response = await Client.PostAsJsonAsync($"/api/lists/{listB.Id}/items",
-            new ShoppingListEndpoints.AddItemRequest("Apples", ProductId: product.Id));
+        var response = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
+            new ShoppingListEndpoints.AddItemRequest("Saffron", ProductId: product.Id));
         var body = await response.Content.ReadFromJsonAsync<JsonElement>();
+
         await Assert.That(body.GetProperty("sectionId").ValueKind).IsEqualTo(JsonValueKind.Null);
     }
 
+    [Test]
+    public async Task Add_item_prefers_family_override_default_over_global_product_default()
+    {
+        var list = await CreateListAsync();
+        var familyId = Store.FamilyId;
+        var (produce, frozen) = await UseDbAsync(async db =>
+        {
+            var p = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            var f = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Frozen", SortOrder = 2 };
+            db.StoreSections.AddRange(p, f);
+            await db.SaveChangesAsync();
+            return (p, f);
+        });
+        var product = await UseDbAsync(async db =>
+        {
+            var p = new Product { Name = "Berries", DefaultSection = "Produce" };
+            db.Products.Add(p);
+            await db.SaveChangesAsync();
+            db.FamilyProductOverrides.Add(new YesChef.Api.Entities.FamilyProductOverride
+            {
+                FamilyId = familyId,
+                ProductId = p.Id,
+                DefaultSection = "Frozen",
+            });
+            await db.SaveChangesAsync();
+            return p;
+        });
+
+        var response = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
+            new ShoppingListEndpoints.AddItemRequest("Berries", ProductId: product.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
+
+        await Assert.That(body.GetProperty("sectionId").GetInt32()).IsEqualTo(frozen.Id);
+    }
+
+    [Test]
+    public async Task Add_item_prefers_per_store_memory_over_family_default()
+    {
+        var list = await CreateListAsync();
+        var familyId = Store.FamilyId;
+        var (produce, pantry) = await UseDbAsync(async db =>
+        {
+            var p = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            var pn = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Pantry", SortOrder = 2 };
+            db.StoreSections.AddRange(p, pn);
+            await db.SaveChangesAsync();
+            return (p, pn);
+        });
+        var product = await UseDbAsync(async db =>
+        {
+            var p = new Product { Name = "Garlic", DefaultSection = "Produce" };
+            db.Products.Add(p);
+            await db.SaveChangesAsync();
+            db.ProductStoreSections.Add(new ProductStoreSection
+            {
+                FamilyId = familyId,
+                StoreId = Store.Id,
+                ProductId = p.Id,
+                StoreSectionId = pantry.Id,
+            });
+            await db.SaveChangesAsync();
+            return p;
+        });
+
+        var response = await Client.PostAsJsonAsync($"/api/lists/{list.Id}/items",
+            new ShoppingListEndpoints.AddItemRequest("Garlic", ProductId: product.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
+
+        await Assert.That(body.GetProperty("sectionId").GetInt32()).IsEqualTo(pantry.Id);
+    }
+
+    [Test]
+    public async Task Patch_item_section_silently_creates_family_override_when_no_default_exists()
+    {
+        var list = await CreateListAsync(b => b.WithItem("Bananas"));
+        var familyId = Store.FamilyId;
+        var produce = await UseDbAsync(async db =>
+        {
+            var s = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            db.StoreSections.Add(s);
+            await db.SaveChangesAsync();
+            return s;
+        });
+        var (itemId, productId) = await UseDbAsync(async db =>
+        {
+            var p = new Product { Name = "Bananas-Silent" };
+            db.Products.Add(p);
+            await db.SaveChangesAsync();
+            var item = await db.ShoppingListItems.SingleAsync(i => i.ShoppingListId == list.Id);
+            item.ProductId = p.Id;
+            await db.SaveChangesAsync();
+            return (item.Id, p.Id);
+        });
+
+        var response = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{itemId}/section",
+            new ShoppingListEndpoints.SetItemSectionRequest(produce.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
+
+        await Assert.That(body.GetProperty("promptSaveDefault").GetBoolean()).IsFalse();
+        var ovr = await UseDbAsync(db => db.FamilyProductOverrides
+            .SingleAsync(o => o.FamilyId == familyId && o.ProductId == productId));
+        await Assert.That(ovr.DefaultSection).IsEqualTo("Produce");
+    }
+
+    [Test]
+    public async Task Patch_item_section_returns_prompt_when_existing_family_default_differs()
+    {
+        var list = await CreateListAsync(b => b.WithItem("Bananas"));
+        var familyId = Store.FamilyId;
+        var (produce, bakery) = await UseDbAsync(async db =>
+        {
+            var p = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            var b = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Bakery", SortOrder = 2 };
+            db.StoreSections.AddRange(p, b);
+            await db.SaveChangesAsync();
+            return (p, b);
+        });
+        var (itemId, productId) = await UseDbAsync(async db =>
+        {
+            var p = new Product { Name = "Banana-Bread" };
+            db.Products.Add(p);
+            await db.SaveChangesAsync();
+            db.FamilyProductOverrides.Add(new YesChef.Api.Entities.FamilyProductOverride
+            {
+                FamilyId = familyId,
+                ProductId = p.Id,
+                DefaultSection = "Bakery",
+            });
+            var item = await db.ShoppingListItems.SingleAsync(i => i.ShoppingListId == list.Id);
+            item.ProductId = p.Id;
+            await db.SaveChangesAsync();
+            return (item.Id, p.Id);
+        });
+
+        // First call without saveAsDefault — should prompt.
+        var promptResponse = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{itemId}/section",
+            new ShoppingListEndpoints.SetItemSectionRequest(produce.Id));
+        var promptBody = await promptResponse.Content.ReadFromJsonAsync<JsonElement>();
+        await Assert.That(promptBody.GetProperty("promptSaveDefault").GetBoolean()).IsTrue();
+        await Assert.That(promptBody.GetProperty("currentDefaultSection").GetString()).IsEqualTo("Bakery");
+        await Assert.That(promptBody.GetProperty("newSectionName").GetString()).IsEqualTo("Produce");
+
+        // Override still says Bakery — item section changed but default untouched.
+        var ovrBefore = await UseDbAsync(db => db.FamilyProductOverrides
+            .SingleAsync(o => o.FamilyId == familyId && o.ProductId == productId));
+        await Assert.That(ovrBefore.DefaultSection).IsEqualTo("Bakery");
+        var itemBefore = await UseDbAsync(db => db.ShoppingListItems.SingleAsync(i => i.Id == itemId));
+        await Assert.That(itemBefore.SectionId).IsEqualTo(produce.Id);
+
+        // Second call with saveAsDefault=true — override updates.
+        var acceptResponse = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{itemId}/section",
+            new ShoppingListEndpoints.SetItemSectionRequest(produce.Id, SaveAsDefault: true));
+        await Assert.That(acceptResponse.StatusCode).IsEqualTo(HttpStatusCode.OK);
+        var ovrAfter = await UseDbAsync(db => db.FamilyProductOverrides
+            .SingleAsync(o => o.FamilyId == familyId && o.ProductId == productId));
+        await Assert.That(ovrAfter.DefaultSection).IsEqualTo("Produce");
+    }
+
+    [Test]
+    public async Task Patch_item_section_no_prompt_when_default_already_matches()
+    {
+        var list = await CreateListAsync(b => b.WithItem("Bananas"));
+        var familyId = Store.FamilyId;
+        var produce = await UseDbAsync(async db =>
+        {
+            var s = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            db.StoreSections.Add(s);
+            await db.SaveChangesAsync();
+            return s;
+        });
+        var itemId = await UseDbAsync(async db =>
+        {
+            var p = new Product { Name = "Bananas-Match" };
+            db.Products.Add(p);
+            await db.SaveChangesAsync();
+            db.FamilyProductOverrides.Add(new YesChef.Api.Entities.FamilyProductOverride
+            {
+                FamilyId = familyId,
+                ProductId = p.Id,
+                DefaultSection = "Produce",
+            });
+            var item = await db.ShoppingListItems.SingleAsync(i => i.ShoppingListId == list.Id);
+            item.ProductId = p.Id;
+            await db.SaveChangesAsync();
+            return item.Id;
+        });
+
+        var response = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{itemId}/section",
+            new ShoppingListEndpoints.SetItemSectionRequest(produce.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
+
+        await Assert.That(body.GetProperty("promptSaveDefault").GetBoolean()).IsFalse();
+    }
+
+    [Test]
+    public async Task Patch_item_section_sets_family_product_default_for_family_products()
+    {
+        var list = await CreateListAsync(b => b.WithItem("House Bread"));
+        var familyId = Store.FamilyId;
+        var bakery = await UseDbAsync(async db =>
+        {
+            var s = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Bakery", SortOrder = 1 };
+            db.StoreSections.Add(s);
+            await db.SaveChangesAsync();
+            return s;
+        });
+        var (itemId, productId) = await UseDbAsync(async db =>
+        {
+            var p = new FamilyProduct { FamilyId = familyId, Name = "House Bread" };
+            db.FamilyProducts.Add(p);
+            await db.SaveChangesAsync();
+            var item = await db.ShoppingListItems.SingleAsync(i => i.ShoppingListId == list.Id);
+            item.FamilyProductId = p.Id;
+            await db.SaveChangesAsync();
+            return (item.Id, p.Id);
+        });
+
+        var response = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{itemId}/section",
+            new ShoppingListEndpoints.SetItemSectionRequest(bakery.Id));
+        await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.OK);
+
+        var fp = await UseDbAsync(db => db.FamilyProducts.SingleAsync(p => p.Id == productId));
+        await Assert.That(fp.DefaultSection).IsEqualTo("Bakery");
+    }
+
+    [Test]
+    public async Task Patch_item_section_without_product_link_does_not_touch_defaults()
+    {
+        var list = await CreateListAsync(b => b.WithItem("free-form"));
+        var familyId = Store.FamilyId;
+        var produce = await UseDbAsync(async db =>
+        {
+            var s = new StoreSection { FamilyId = familyId, StoreId = Store.Id, Name = "Produce", SortOrder = 1 };
+            db.StoreSections.Add(s);
+            await db.SaveChangesAsync();
+            return s;
+        });
+        var itemId = await UseDbAsync(db => db.ShoppingListItems
+            .Where(i => i.ShoppingListId == list.Id).Select(i => i.Id).SingleAsync());
+
+        var response = await Client.PatchAsJsonAsync($"/api/lists/{list.Id}/items/{itemId}/section",
+            new ShoppingListEndpoints.SetItemSectionRequest(produce.Id));
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>();
+
+        await Assert.That(body.GetProperty("promptSaveDefault").GetBoolean()).IsFalse();
+        await Assert.That(await UseDbAsync(db => db.FamilyProductOverrides.AnyAsync())).IsFalse();
+    }
+
     [Test]
     public async Task Add_item_rejects_other_familys_family_product()
     {

src/backend/YesChef.Api/Data/YesChefDb.cs

@@ -141,6 +141,7 @@ public class YesChefDb(DbContextOptions<YesChefDb> options) : DbContext(options)
             e.Property(p => p.Brand).HasMaxLength(200);
             e.Property(p => p.Notes).HasMaxLength(1000);
             e.Property(p => p.AllowedUnitCategories).HasConversion<int>();
+            e.Property(p => p.DefaultSection).HasMaxLength(100);
             e.HasIndex(p => p.Name).IsUnique();
         });
 
@@ -150,6 +151,7 @@ public class YesChefDb(DbContextOptions<YesChefDb> options) : DbContext(options)
             e.Property(p => p.Brand).HasMaxLength(200);
             e.Property(p => p.Notes).HasMaxLength(1000);
             e.Property(p => p.AllowedUnitCategories).HasConversion<int>();
+            e.Property(p => p.DefaultSection).HasMaxLength(100);
             e.HasOne(p => p.Family).WithMany().HasForeignKey(p => p.FamilyId).OnDelete(DeleteBehavior.Cascade);
             e.HasIndex(p => new { p.FamilyId, p.Name }).IsUnique();
         });
@@ -161,6 +163,7 @@ public class YesChefDb(DbContextOptions<YesChefDb> options) : DbContext(options)
             e.Property(o => o.Brand).HasMaxLength(200);
             e.Property(o => o.Notes).HasMaxLength(1000);
             e.Property(o => o.AllowedUnitCategories).HasConversion<int?>();
+            e.Property(o => o.DefaultSection).HasMaxLength(100);
             e.HasOne(o => o.Family).WithMany().HasForeignKey(o => o.FamilyId).OnDelete(DeleteBehavior.Cascade);
             e.HasOne(o => o.Product).WithMany().HasForeignKey(o => o.ProductId).OnDelete(DeleteBehavior.Cascade);
         });

src/backend/YesChef.Api/Entities/FamilyProduct.cs

@@ -13,5 +13,6 @@ public class FamilyProduct
     public string? Brand { get; set; }
     public string? Notes { get; set; }
     public UnitCategoryFlags AllowedUnitCategories { get; set; }
+    public string? DefaultSection { get; set; }
     public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
 }

src/backend/YesChef.Api/Entities/FamilyProductOverride.cs

@@ -18,5 +18,8 @@ public class FamilyProductOverride
     // Nullable so "inherit global" (null) is distinguishable from
     // "explicitly None / any unit" (UnitCategoryFlags.None).
     public UnitCategoryFlags? AllowedUnitCategories { get; set; }
+    // Null = inherit Product.DefaultSection. Non-null = family override of
+    // the recommended section name.
+    public string? DefaultSection { get; set; }
     public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
 }

src/backend/YesChef.Api/Entities/Product.cs

@@ -14,5 +14,10 @@ public class Product
     // None = "any unit". Non-zero narrows the unit-dropdown suggestions to the
     // flagged categories. Families can replace this with FamilyProductOverride.
     public UnitCategoryFlags AllowedUnitCategories { get; set; }
+    // Recommended section name (e.g. "Produce"). Resolved at runtime against
+    // the active store's StoreSection rows by case-insensitive name match —
+    // sections are family/store-scoped so there's no FK relationship. Family
+    // overrides take precedence; per-store memory takes precedence over both.
+    public string? DefaultSection { get; set; }
     public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
 }

src/backend/YesChef.Api/Features/Products/ProductEndpoints.cs

@@ -3,7 +3,6 @@ using Microsoft.EntityFrameworkCore;
 using YesChef.Api.Auth;
 using YesChef.Api.Data;
 using YesChef.Api.Entities;
-using YesChef.Api.Features.ShoppingLists;
 
 namespace YesChef.Api.Features.Products;
 
@@ -22,10 +21,11 @@ public static class ProductEndpoints
         string? Brand,
         string? Notes,
         bool IsOverridden,
-        UnitCategoryFlags AllowedUnitCategories);
+        UnitCategoryFlags AllowedUnitCategories,
+        string? DefaultSection);
 
-    public record CreateProductRequest(string Name, string? Brand, string? Notes, UnitCategoryFlags AllowedUnitCategories = UnitCategoryFlags.None);
-    public record UpdateProductRequest(string? Name, string? Brand, string? Notes, UnitCategoryFlags? AllowedUnitCategories = null);
+    public record CreateProductRequest(string Name, string? Brand, string? Notes, UnitCategoryFlags AllowedUnitCategories = UnitCategoryFlags.None, string? DefaultSection = null);
+    public record UpdateProductRequest(string? Name, string? Brand, string? Notes, UnitCategoryFlags? AllowedUnitCategories = null, string? DefaultSection = null);
 
     private const int SearchResultLimit = 50;
 
@@ -59,10 +59,12 @@ public static class ProductEndpoints
                     GlobalBrand = p.Brand,
                     GlobalNotes = p.Notes,
                     GlobalAllowedUnitCategories = p.AllowedUnitCategories,
+                    GlobalDefaultSection = p.DefaultSection,
                     OverrideName = o != null ? o.Name : null,
                     OverrideBrand = o != null ? o.Brand : null,
                     OverrideNotes = o != null ? o.Notes : null,
                     OverrideAllowedUnitCategories = o != null ? o.AllowedUnitCategories : null,
+                    OverrideDefaultSection = o != null ? o.DefaultSection : null,
                     HasOverride = o != null,
                 })
                 .Take(SearchResultLimit)
@@ -89,11 +91,12 @@ public static class ProductEndpoints
                     r.OverrideBrand ?? r.GlobalBrand,
                     r.OverrideNotes ?? r.GlobalNotes,
                     r.HasOverride,
-                    r.OverrideAllowedUnitCategories ?? r.GlobalAllowedUnitCategories);
+                    r.OverrideAllowedUnitCategories ?? r.GlobalAllowedUnitCategories,
+                    r.OverrideDefaultSection ?? r.GlobalDefaultSection);
             }).Where(d => d is not null).Cast<ProductDto>();
 
             var familyDtos = familyRows.Select(p =>
-                new ProductDto(p.Id, ProductKind.Family, p.Name, p.Brand, p.Notes, IsOverridden: false, p.AllowedUnitCategories));
+                new ProductDto(p.Id, ProductKind.Family, p.Name, p.Brand, p.Notes, IsOverridden: false, p.AllowedUnitCategories, p.DefaultSection));
 
             var results = globalDtos.Concat(familyDtos)
                 .OrderBy(d => d.Name, StringComparer.OrdinalIgnoreCase)
@@ -122,6 +125,7 @@ public static class ProductEndpoints
                 Brand = request.Brand,
                 Notes = request.Notes,
                 AllowedUnitCategories = request.AllowedUnitCategories,
+                DefaultSection = NormalizeSection(request.DefaultSection),
             };
             db.FamilyProducts.Add(product);
             await db.SaveChangesAsync();
@@ -151,6 +155,7 @@ public static class ProductEndpoints
             product.Brand = request.Brand;
             product.Notes = request.Notes;
             if (request.AllowedUnitCategories is { } cats) product.AllowedUnitCategories = cats;
+            product.DefaultSection = NormalizeSection(request.DefaultSection);
             await db.SaveChangesAsync();
 
             return Results.Ok(ToDto(product));
@@ -195,7 +200,8 @@ public static class ProductEndpoints
                 product.Brand,
                 product.Notes,
                 IsOverridden: false,
-                product.AllowedUnitCategories));
+                product.AllowedUnitCategories,
+                product.DefaultSection));
         });
 
         // Update a global product for this family by upserting an override.
@@ -229,6 +235,7 @@ public static class ProductEndpoints
             // itself be null, i.e. "inherit global"). Pass an explicit value to
             // either narrow categories or restore "any" (UnitCategoryFlags.None).
             if (request.AllowedUnitCategories is { } cats) ovr.AllowedUnitCategories = cats;
+            ovr.DefaultSection = NormalizeSection(request.DefaultSection);
             ovr.UpdatedAt = DateTime.UtcNow;
             await db.SaveChangesAsync();
 
@@ -239,36 +246,26 @@ public static class ProductEndpoints
                 ovr.Brand ?? product.Brand,
                 ovr.Notes ?? product.Notes,
                 IsOverridden: true,
-                ovr.AllowedUnitCategories ?? product.AllowedUnitCategories));
-        });
-
-        // Look up the per-store section memory for a product so the add-item
-        // UI can pre-fill the dropdown the moment the user picks a product
-        // from the typeahead. The backend already applies this memory on POST
-        // when no section is supplied — this endpoint just lets the client
-        // mirror that decision so the user can see (and override) it.
-        // Returns { sectionId: int | null }. No memory → null, not 404.
-        group.MapGet("/global/{id:int}/section", async (int id, int storeId, YesChefDb db, HttpContext http) =>
-        {
-            var familyId = http.User.GetFamilyId();
-            var sectionId = await ShoppingListEndpoints.LookupRememberedSectionAsync(db, familyId, storeId, id, null);
-            return Results.Ok(new { sectionId });
-        });
-
-        group.MapGet("/family/{id:int}/section", async (int id, int storeId, YesChefDb db, HttpContext http) =>
-        {
-            var familyId = http.User.GetFamilyId();
-            // FamilyProducts are tenant-scoped — refuse to leak even the
-            // existence of another family's product id.
-            if (!await db.FamilyProducts.AnyAsync(p => p.Id == id && p.FamilyId == familyId))
-                return Results.NotFound();
-            var sectionId = await ShoppingListEndpoints.LookupRememberedSectionAsync(db, familyId, storeId, null, id);
-            return Results.Ok(new { sectionId });
+                ovr.AllowedUnitCategories ?? product.AllowedUnitCategories,
+                ovr.DefaultSection ?? product.DefaultSection));
         });
 
         return group;
     }
 
     private static ProductDto ToDto(FamilyProduct p) =>
-        new(p.Id, ProductKind.Family, p.Name, p.Brand, p.Notes, IsOverridden: false, p.AllowedUnitCategories);
+        new(p.Id, ProductKind.Family, p.Name, p.Brand, p.Notes, IsOverridden: false, p.AllowedUnitCategories, p.DefaultSection);
+
+    /// <summary>
+    /// Strip whitespace; turn empty into null so "no default" round-trips
+    /// consistently regardless of whether the client sends `""` or omits the
+    /// field. Storing whitespace would also break the case-insensitive match
+    /// against StoreSection names.
+    /// </summary>
+    private static string? NormalizeSection(string? value)
+    {
+        if (value is null) return null;
+        var trimmed = value.Trim();
+        return trimmed.Length == 0 ? null : trimmed;
+    }
 }

src/backend/YesChef.Api/Features/ShoppingLists/ShoppingListEndpoints.cs

@@ -22,7 +22,19 @@ public static class ShoppingListEndpoints
         int? FamilyUnitOfMeasureId = null,
         bool IsApproximate = false,
         string? QuantityNote = null);
-    public record SetItemSectionRequest(int? SectionId);
+    public record SetItemSectionRequest(int? SectionId, bool SaveAsDefault = false);
+
+    /// <summary>
+    /// Response shape for the section PATCH. When the item is linked to a
+    /// product and the family-level default exists with a different name,
+    /// <see cref="PromptSaveDefault"/> is true and the client should ask the
+    /// user whether to update the default. Re-call with SaveAsDefault=true to
+    /// accept.
+    /// </summary>
+    public record SetItemSectionResponse(
+        bool PromptSaveDefault,
+        string? CurrentDefaultSection,
+        string? NewSectionName);
 
     private static string OverviewGroup(int familyId) => $"lists-overview-{familyId}";
 
@@ -216,11 +228,10 @@ public static class ShoppingListEndpoints
             if (await ValidateUnitLink(db, familyId, request.UnitOfMeasureId, request.FamilyUnitOfMeasureId) is { } unitError)
                 return unitError;
 
-            // Auto-assign a section from memory when caller didn't pick one
-            // but supplied a product link — "we put bananas in Produce last
-            // time we shopped here, do it again."
+            // No explicit section → resolve through the product's defaults
+            // (per-store memory → family default → global default).
             var resolvedSectionId = request.SectionId
-                ?? await LookupRememberedSectionAsync(db, familyId, list.StoreId, request.ProductId, request.FamilyProductId);
+                ?? await ResolveSectionAsync(db, familyId, list.StoreId, request.ProductId, request.FamilyProductId);
 
             var item = new ShoppingListItem
             {
@@ -240,12 +251,6 @@ public static class ShoppingListEndpoints
             db.ShoppingListItems.Add(item);
             list.UpdatedAt = DateTime.UtcNow;
 
-            // If the caller explicitly chose a section, record/update memory
-            // for next time. Auto-assigned sections don't need a write back —
-            // the existing memory row already says exactly this.
-            if (request.SectionId.HasValue)
-                await RememberSectionAsync(db, familyId, list.StoreId, request.ProductId, request.FamilyProductId, request.SectionId);
-
             await AllowedUnitCategoryLearner.LearnAsync(db, familyId, new[]
             {
                 new AllowedUnitCategoryLearner.Pair(request.ProductId, request.FamilyProductId, item.UnitOfMeasureId, item.FamilyUnitOfMeasureId),
@@ -266,18 +271,47 @@ public static class ShoppingListEndpoints
                 .FirstOrDefaultAsync(i => i.Id == itemId && i.ShoppingListId == listId && i.FamilyId == familyId && i.RemovedAt == null);
             if (item is null) return Results.NotFound();
 
-            if (request.SectionId is int sectionId &&
-                !await db.StoreSections.AnyAsync(s => s.Id == sectionId && s.StoreId == item.ShoppingList.StoreId && s.FamilyId == familyId))
-                return Results.BadRequest(new { error = "Unknown section." });
+            string? newSectionName = null;
+            if (request.SectionId is int sectionId)
+            {
+                var section = await db.StoreSections
+                    .Where(s => s.Id == sectionId && s.StoreId == item.ShoppingList.StoreId && s.FamilyId == familyId)
+                    .Select(s => new { s.Name })
+                    .FirstOrDefaultAsync();
+                if (section is null) return Results.BadRequest(new { error = "Unknown section." });
+                newSectionName = section.Name;
+            }
 
             item.SectionId = request.SectionId;
-            // Manual section change is the user correcting the memory: persist
-            // the new mapping so future adds at this store learn from it.
-            await RememberSectionAsync(db, familyId, item.ShoppingList.StoreId, item.ProductId, item.FamilyProductId, request.SectionId);
+
+            // For product-linked items, sync the family-level default. The
+            // rules per spec:
+            //   - No existing default (override or family product) → set it
+            //     silently. Creates a FamilyProductOverride for globals.
+            //   - Existing default matches → no-op.
+            //   - Existing default differs:
+            //       * SaveAsDefault=true → update.
+            //       * Otherwise → return PromptSaveDefault=true so the client
+            //         can ask the user. The item section change still sticks.
+            var prompt = false;
+            string? currentDefault = null;
+            if (newSectionName is not null && (item.ProductId.HasValue || item.FamilyProductId.HasValue))
+            {
+                currentDefault = await GetFamilyDefaultSectionNameAsync(db, familyId, item.ProductId, item.FamilyProductId);
+                var matches = currentDefault is not null
+                    && string.Equals(currentDefault.Trim(), newSectionName.Trim(), StringComparison.OrdinalIgnoreCase);
+                var noDefaultYet = string.IsNullOrWhiteSpace(currentDefault);
+
+                if (noDefaultYet || request.SaveAsDefault)
+                    await SetFamilyDefaultSectionAsync(db, familyId, item.ProductId, item.FamilyProductId, newSectionName);
+                else if (!matches)
+                    prompt = true;
+            }
+
             await db.SaveChangesAsync();
 
             await hub.Clients.Group($"list-{listId}").SendAsync("ItemSectionChanged", new { item.Id, item.SectionId });
-            return Results.Ok();
+            return Results.Ok(new SetItemSectionResponse(prompt, currentDefault, newSectionName));
         });
 
         group.MapPatch("/{listId:int}/items/{itemId:int}/check", async (int listId, int itemId, YesChefDb db, IHubContext<ShoppingListHub> hub, HttpContext http) =>
@@ -370,9 +404,9 @@ public static class ShoppingListEndpoints
             var idx = 0;
             foreach (var ing in recipe.Ingredients)
             {
-                // Carry the ingredient's product link onto the list item, and
-                // use the per-store memory to assign a section if we have one.
-                var rememberedSectionId = await LookupRememberedSectionAsync(db, familyId, list.StoreId, ing.ProductId, ing.FamilyProductId);
+                // Carry the ingredient's product link onto the list item and
+                // resolve a section through the product's defaults if any.
+                var rememberedSectionId = await ResolveSectionAsync(db, familyId, list.StoreId, ing.ProductId, ing.FamilyProductId);
 
                 newItems.Add(new ShoppingListItem
                 {
@@ -470,50 +504,127 @@ public static class ShoppingListEndpoints
     }
 
     /// <summary>
-    /// Look up the section a product was last placed in at this store, for
-    /// this family. Returns null if no memory exists or no product link was
-    /// supplied.
+    /// Resolve the effective section for a product-linked item at this store.
+    /// Tiers, highest priority first:
+    ///   1. ProductStoreSection — per-store explicit override.
+    ///   2. Family default — FamilyProductOverride.DefaultSection (global product)
+    ///      or FamilyProduct.DefaultSection (family product), matched by name
+    ///      against this store's sections.
+    ///   3. Global default — Product.DefaultSection, matched by name.
+    /// Returns null when no tier produces a section (or no product is linked).
     /// </summary>
-    internal static async Task<int?> LookupRememberedSectionAsync(YesChefDb db, int familyId, int storeId, int? productId, int? familyProductId)
+    internal static async Task<int?> ResolveSectionAsync(YesChefDb db, int familyId, int storeId, int? productId, int? familyProductId)
     {
         if (!productId.HasValue && !familyProductId.HasValue) return null;
 
-        return await db.ProductStoreSections
+        var perStore = await db.ProductStoreSections
             .Where(p => p.FamilyId == familyId && p.StoreId == storeId
                 && p.ProductId == productId && p.FamilyProductId == familyProductId)
             .Select(p => (int?)p.StoreSectionId)
             .FirstOrDefaultAsync();
+        if (perStore.HasValue) return perStore;
+
+        var defaultName = await GetEffectiveDefaultSectionNameAsync(db, familyId, productId, familyProductId);
+        if (string.IsNullOrWhiteSpace(defaultName)) return null;
+
+        return await db.StoreSections
+            .Where(s => s.StoreId == storeId && s.FamilyId == familyId
+                && EF.Functions.ILike(s.Name, defaultName.Trim()))
+            .Select(s => (int?)s.Id)
+            .FirstOrDefaultAsync();
     }
 
     /// <summary>
-    /// Upsert the (Family, Store, Product) → Section memory. No-op if no
-    /// product link or no section is supplied. Caller must ensure section
-    /// belongs to the same store and family.
+    /// Family-level default section name only — FamilyProductOverride for a
+    /// global product, or FamilyProduct.DefaultSection for a family product.
+    /// Does NOT fall back to the global Product default. Use this when
+    /// deciding whether the family has its own override and whether a prompt
+    /// is needed before changing it.
     /// </summary>
-    internal static async Task RememberSectionAsync(YesChefDb db, int familyId, int storeId, int? productId, int? familyProductId, int? sectionId)
+    internal static async Task<string?> GetFamilyDefaultSectionNameAsync(YesChefDb db, int familyId, int? productId, int? familyProductId)
     {
-        if (!sectionId.HasValue) return;
-        if (!productId.HasValue && !familyProductId.HasValue) return;
-
-        var existing = await db.ProductStoreSections
-            .FirstOrDefaultAsync(p => p.FamilyId == familyId && p.StoreId == storeId
-                && p.ProductId == productId && p.FamilyProductId == familyProductId);
-
-        if (existing is null)
+        if (productId.HasValue)
         {
-            db.ProductStoreSections.Add(new ProductStoreSection
-            {
-                FamilyId = familyId,
-                StoreId = storeId,
-                ProductId = productId,
-                FamilyProductId = familyProductId,
-                StoreSectionId = sectionId.Value,
-            });
+            return await db.FamilyProductOverrides.AsNoTracking()
+                .Where(o => o.FamilyId == familyId && o.ProductId == productId)
+                .Select(o => o.DefaultSection)
+                .FirstOrDefaultAsync();
         }
-        else if (existing.StoreSectionId != sectionId.Value)
+        if (familyProductId.HasValue)
         {
-            existing.StoreSectionId = sectionId.Value;
-            existing.UpdatedAt = DateTime.UtcNow;
+            return await db.FamilyProducts.AsNoTracking()
+                .Where(p => p.Id == familyProductId && p.FamilyId == familyId)
+                .Select(p => p.DefaultSection)
+                .FirstOrDefaultAsync();
+        }
+        return null;
+    }
+
+    /// <summary>
+    /// Persist the family-level default section. For global products, upserts
+    /// a FamilyProductOverride; for family products, mutates the row directly.
+    /// Caller is responsible for SaveChangesAsync.
+    /// </summary>
+    internal static async Task SetFamilyDefaultSectionAsync(YesChefDb db, int familyId, int? productId, int? familyProductId, string sectionName)
+    {
+        if (productId.HasValue)
+        {
+            var ovr = await db.FamilyProductOverrides
+                .FirstOrDefaultAsync(o => o.FamilyId == familyId && o.ProductId == productId);
+            if (ovr is null)
+            {
+                db.FamilyProductOverrides.Add(new Entities.FamilyProductOverride
+                {
+                    FamilyId = familyId,
+                    ProductId = productId.Value,
+                    DefaultSection = sectionName,
+                });
+            }
+            else
+            {
+                ovr.DefaultSection = sectionName;
+                ovr.UpdatedAt = DateTime.UtcNow;
+            }
+            return;
+        }
+        if (familyProductId.HasValue)
+        {
+            var fp = await db.FamilyProducts
+                .FirstOrDefaultAsync(p => p.Id == familyProductId && p.FamilyId == familyId);
+            if (fp is not null)
+                fp.DefaultSection = sectionName;
         }
     }
+
+    /// <summary>
+    /// Effective default section name for a product, walking the family
+    /// override (or family product) and falling back to the global product.
+    /// Pure read — does not consider per-store memory or section availability.
+    /// </summary>
+    internal static async Task<string?> GetEffectiveDefaultSectionNameAsync(YesChefDb db, int familyId, int? productId, int? familyProductId)
+    {
+        if (productId.HasValue)
+        {
+            var row = await (
+                from p in db.Products.AsNoTracking()
+                where p.Id == productId
+                join o in db.FamilyProductOverrides.Where(o => o.FamilyId == familyId)
+                    on p.Id equals o.ProductId into overrides
+                from o in overrides.DefaultIfEmpty()
+                select new { Override = o != null ? o.DefaultSection : null, Global = p.DefaultSection }
+            ).FirstOrDefaultAsync();
+
+            return row?.Override ?? row?.Global;
+        }
+
+        if (familyProductId.HasValue)
+        {
+            return await db.FamilyProducts.AsNoTracking()
+                .Where(p => p.Id == familyProductId && p.FamilyId == familyId)
+                .Select(p => p.DefaultSection)
+                .FirstOrDefaultAsync();
+        }
+
+        return null;
+    }
 }

src/backend/YesChef.Api/Migrations/20260516025713_AddProductDefaultSection.cs

@@ -0,0 +1,51 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace YesChef.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddProductDefaultSection : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "DefaultSection",
+                table: "Products",
+                type: "character varying(100)",
+                maxLength: 100,
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "DefaultSection",
+                table: "FamilyProducts",
+                type: "character varying(100)",
+                maxLength: 100,
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "DefaultSection",
+                table: "FamilyProductOverrides",
+                type: "character varying(100)",
+                maxLength: 100,
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "DefaultSection",
+                table: "Products");
+
+            migrationBuilder.DropColumn(
+                name: "DefaultSection",
+                table: "FamilyProducts");
+
+            migrationBuilder.DropColumn(
+                name: "DefaultSection",
+                table: "FamilyProductOverrides");
+        }
+    }
+}

src/backend/YesChef.Api/Migrations/YesChefDbModelSnapshot.cs

@@ -90,6 +90,10 @@ namespace YesChef.Api.Migrations
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("timestamp with time zone");
 
+                    b.Property<string>("DefaultSection")
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
                     b.Property<int>("FamilyId")
                         .HasColumnType("integer");
 
@@ -125,6 +129,10 @@ namespace YesChef.Api.Migrations
                         .HasMaxLength(200)
                         .HasColumnType("character varying(200)");
 
+                    b.Property<string>("DefaultSection")
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
                     b.Property<string>("Name")
                         .HasMaxLength(200)
                         .HasColumnType("character varying(200)");
@@ -289,6 +297,10 @@ namespace YesChef.Api.Migrations
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("timestamp with time zone");
 
+                    b.Property<string>("DefaultSection")
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
                     b.Property<string>("Name")
                         .IsRequired()
                         .HasMaxLength(200)

src/frontend/src/lib/ProductTypeahead.svelte

@@ -17,6 +17,7 @@
 		notes: string | null;
 		isOverridden: boolean;
 		allowedUnitCategories: number;
+		defaultSection: string | null;
 	}
 </script>
 

src/frontend/src/lib/TextCombobox.svelte

@@ -0,0 +1,124 @@
+<script lang="ts">
+	// Free-text input with a styled dropdown of static suggestions. Users can
+	// pick from the list or type a custom value — whatever's in the input is
+	// what binds.
+	//
+	// Use this when the suggestion set is a small, static list of strings
+	// (e.g. common section names, predefined tags). For API-driven typeahead
+	// returning structured objects (products, users, etc.), use
+	// ProductTypeahead.svelte as the pattern. Look & keyboard behavior here
+	// intentionally mirror ProductTypeahead so the two feel like siblings.
+
+	interface Props {
+		value: string;
+		suggestions: readonly string[];
+		placeholder?: string;
+		ariaLabel?: string;
+		inputClass?: string;
+	}
+
+	let {
+		value = $bindable(''),
+		suggestions,
+		placeholder = '',
+		ariaLabel,
+		inputClass = '',
+	}: Props = $props();
+
+	let showDropdown = $state(false);
+	let activeIndex = $state(-1);
+	const listboxId = `text-combobox-${crypto.randomUUID().slice(0, 8)}`;
+
+	// Filter on substring (case-insensitive). Empty input shows everything so
+	// the user can scan the seeded list without typing first.
+	const filtered = $derived.by(() => {
+		const q = value.trim().toLowerCase();
+		if (q.length === 0) return [...suggestions];
+		return suggestions.filter((s) => s.toLowerCase().includes(q));
+	});
+
+	function selectSuggestion(s: string) {
+		value = s;
+		showDropdown = false;
+		activeIndex = -1;
+	}
+
+	function onInput() {
+		showDropdown = filtered.length > 0;
+		activeIndex = -1;
+	}
+
+	function onKeydown(e: KeyboardEvent) {
+		if (!showDropdown || filtered.length === 0) return;
+		if (e.key === 'ArrowDown') {
+			e.preventDefault();
+			activeIndex = (activeIndex + 1) % filtered.length;
+		} else if (e.key === 'ArrowUp') {
+			e.preventDefault();
+			activeIndex = activeIndex <= 0 ? filtered.length - 1 : activeIndex - 1;
+		} else if (e.key === 'Enter') {
+			if (activeIndex >= 0) {
+				e.preventDefault();
+				selectSuggestion(filtered[activeIndex]);
+			}
+		} else if (e.key === 'Escape') {
+			showDropdown = false;
+			activeIndex = -1;
+		}
+	}
+
+	function onBlur() {
+		// Delay so a mousedown-then-mouseup click on a suggestion is recorded
+		// before the dropdown closes.
+		setTimeout(() => {
+			showDropdown = false;
+			activeIndex = -1;
+		}, 120);
+	}
+</script>
+
+<div class="relative">
+	<input
+		type="text"
+		bind:value
+		oninput={onInput}
+		onkeydown={onKeydown}
+		onblur={onBlur}
+		onfocus={() => {
+			if (filtered.length > 0) showDropdown = true;
+		}}
+		{placeholder}
+		aria-label={ariaLabel}
+		aria-autocomplete="list"
+		aria-expanded={showDropdown}
+		aria-controls={listboxId}
+		role="combobox"
+		class={inputClass}
+		autocomplete="off"
+	/>
+
+	{#if showDropdown}
+		<ul
+			id={listboxId}
+			class="absolute left-0 right-0 z-10 mt-1 max-h-64 overflow-auto rounded-lg border border-gray-200 bg-white shadow-lg"
+			role="listbox"
+		>
+			{#each filtered as suggestion, i (suggestion)}
+				<li
+					role="option"
+					aria-selected={i === activeIndex}
+					class="cursor-pointer px-3 py-2 text-sm {i === activeIndex
+						? 'bg-primary/10'
+						: 'hover:bg-gray-50'}"
+					onmousedown={(e) => {
+						// mousedown rather than click so we beat the blur handler.
+						e.preventDefault();
+						selectSuggestion(suggestion);
+					}}
+				>
+					{suggestion}
+				</li>
+			{/each}
+		</ul>
+	{/if}
+</div>

src/frontend/src/lib/typicalSections.ts

@@ -0,0 +1,15 @@
+// Suggested grocery store section names — used to seed autocomplete for the
+// product default-section field. Mirrors StoreSectionDefaults.Names on the
+// backend; kept here as a static constant since it changes rarely and the
+// list is tiny. Custom entries are still allowed.
+export const typicalSections = [
+	'Produce',
+	'Meat & Seafood',
+	'Dairy',
+	'Bakery',
+	'Frozen',
+	'Pantry',
+	'Condiments',
+	'Beverages',
+	'Other',
+] as const;

src/frontend/src/routes/lists/[id]/+page.svelte

@@ -47,7 +47,6 @@
 	let items = $state<ListItem[]>([]);
 	let sections = $state<Section[]>([]);
 	let newItemName = $state('');
-	let newItemSectionId = $state<number | null>(null);
 	let newItemProductId = $state<number | null>(null);
 	let newItemFamilyProductId = $state<number | null>(null);
 	let newItemQuantity = $state<QuantityValue>({ quantity: null, unitOfMeasureId: null, familyUnitOfMeasureId: null });
@@ -56,9 +55,6 @@
 	let newItemAllowedUnitCategories = $state(0);
 	let loading = $state(true);
 	let connection: HubConnection | null = null;
-	// Seq guard so a slow section lookup can't overwrite the section a
-	// later (faster) product pick already set.
-	let sectionLookupSeq = 0;
 
 	const listId = $derived(Number(page.params.id));
 	const uncheckedItems = $derived(items.filter((i) => !i.isChecked));
@@ -173,12 +169,14 @@
 	async function addItem() {
 		if (!newItemName.trim()) return;
 		const maxSort = items.length > 0 ? Math.max(...items.map((i) => i.sortOrder)) : 0;
+		// No explicit section is sent — the backend resolves one from the
+		// product's defaults (per-store memory → family default → global
+		// default). The user adjusts after the fact on the list row.
 		await api('/api/lists/' + listId + '/items', {
 			method: 'POST',
 			body: JSON.stringify({
 				name: newItemName,
 				sortOrder: maxSort + 1,
-				sectionId: newItemSectionId,
 				productId: newItemProductId,
 				familyProductId: newItemFamilyProductId,
 				quantity: newItemIsApproximate ? null : newItemQuantity.quantity,
@@ -206,14 +204,11 @@
 		}
 	}
 
-	async function onItemProductChange(product: ProductSuggestion | null) {
-		const seq = ++sectionLookupSeq;
+	function onItemProductChange(product: ProductSuggestion | null) {
 		if (product === null) {
 			newItemProductId = null;
 			newItemFamilyProductId = null;
 			newItemAllowedUnitCategories = 0;
-			// Don't clobber the user's section choice when they edit the
-			// name and the link clears — they may have set it deliberately.
 			return;
 		}
 		if (product.kind === 'Global') {
@@ -224,22 +219,6 @@
 			newItemFamilyProductId = product.id;
 		}
 		newItemAllowedUnitCategories = product.allowedUnitCategories;
-
-		// Mirror the backend's auto-assign rule: pre-fill the section dropdown
-		// from per-store memory so the user can see (and override) what's
-		// about to happen. Null result means no memory — reset to "No section".
-		if (!list) return;
-		const path = product.kind === 'Global' ? 'global' : 'family';
-		try {
-			const res = await api<{ sectionId: number | null }>(
-				`/api/products/${path}/${product.id}/section?storeId=${list.store.id}`
-			);
-			if (seq !== sectionLookupSeq) return;
-			newItemSectionId = res.sectionId;
-		} catch {
-			// Lookup failure shouldn't block adding an item — leave the
-			// section alone and let the backend auto-assign on POST.
-		}
 	}
 
 	async function toggleItem(itemId: number) {
@@ -250,10 +229,29 @@
 		// Optimistic — the SignalR ItemSectionChanged echo will reconcile.
 		items = items.map((i) => (i.id === itemId ? { ...i, sectionId } : i));
 		try {
-			await api(`/api/lists/${listId}/items/${itemId}/section`, {
+			const res = await api<{
+				promptSaveDefault: boolean;
+				currentDefaultSection: string | null;
+				newSectionName: string | null;
+			}>(`/api/lists/${listId}/items/${itemId}/section`, {
 				method: 'PATCH',
 				body: JSON.stringify({ sectionId })
 			});
+
+			// Product had an existing family default that differs from this
+			// new choice. Ask whether to update the default — accepting
+			// re-PATCHes with saveAsDefault, declining leaves it as a one-off.
+			if (res.promptSaveDefault && res.newSectionName) {
+				const productName = items.find((i) => i.id === itemId)?.name ?? 'this product';
+				const message = `Save “${productName}” → ${res.newSectionName} as the default? ` +
+					`(currently ${res.currentDefaultSection})`;
+				if (confirm(message)) {
+					await api(`/api/lists/${listId}/items/${itemId}/section`, {
+						method: 'PATCH',
+						body: JSON.stringify({ sectionId, saveAsDefault: true })
+					});
+				}
+			}
 		} catch (e) {
 			toast.error(e instanceof Error ? e.message : 'Failed to update section');
 		}
@@ -319,7 +317,7 @@
 				onsubmit={addItem}
 				onProductChange={onItemProductChange}
 			/>
-			<div class="flex flex-wrap gap-2">
+			<div class="flex flex-wrap items-start gap-2">
 				{#if newItemIsApproximate}
 					<input
 						type="text"
@@ -333,18 +331,6 @@
 						allowedUnitCategories={newItemAllowedUnitCategories}
 					/>
 				{/if}
-				{#if sections.length > 0}
-					<select
-						bind:value={newItemSectionId}
-						class="select max-w-36 px-2"
-						aria-label="Section"
-					>
-						<option value={null}>No section</option>
-						{#each sections as section (section.id)}
-							<option value={section.id}>{section.name}</option>
-						{/each}
-					</select>
-				{/if}
 				<button
 					type="submit"
 					class="btn-primary"

src/frontend/src/routes/products/+page.svelte

@@ -3,6 +3,8 @@
 	import { api } from '$lib/api';
 	import { toast } from '$lib/toast.svelte';
 	import { UnitCategoryFlag, type ProductSuggestion } from '$lib/ProductTypeahead.svelte';
+	import TextCombobox from '$lib/TextCombobox.svelte';
+	import { typicalSections } from '$lib/typicalSections';
 
 	let products = $state<ProductSuggestion[]>([]);
 	let query = $state('');
@@ -17,6 +19,7 @@
 	let formName = $state('');
 	let formBrand = $state('');
 	let formNotes = $state('');
+	let formDefaultSection = $state('');
 	// Bitfield matching the backend UnitCategoryFlags. 0 = "any unit allowed".
 	let formCategories = $state(0);
 	let saving = $state(false);
@@ -63,6 +66,7 @@
 		formName = '';
 		formBrand = '';
 		formNotes = '';
+		formDefaultSection = '';
 		formCategories = 0;
 		formOpen = true;
 	}
@@ -72,6 +76,7 @@
 		formName = p.name;
 		formBrand = p.brand ?? '';
 		formNotes = p.notes ?? '';
+		formDefaultSection = p.defaultSection ?? '';
 		formCategories = p.allowedUnitCategories;
 		formOpen = true;
 	}
@@ -94,7 +99,8 @@
 				name,
 				brand: formBrand.trim() || null,
 				notes: formNotes.trim() || null,
-				allowedUnitCategories: formCategories
+				allowedUnitCategories: formCategories,
+				defaultSection: formDefaultSection.trim() || null
 			};
 			if (editingProduct === null) {
 				await api('/api/products', { method: 'POST', body: JSON.stringify(body) });
@@ -203,6 +209,9 @@
 						{#if product.brand}
 							<div class="text-xs text-gray-400">{product.brand}</div>
 						{/if}
+						{#if product.defaultSection}
+							<div class="text-xs text-gray-400">Section: {product.defaultSection}</div>
+						{/if}
 					</div>
 					<button onclick={() => startEdit(product)} class="text-sm text-gray-400">Edit</button>
 				</li>
@@ -255,6 +264,24 @@
 					>
 					<textarea bind:value={formNotes} rows="2" class="field mt-1 w-full"></textarea>
 				</label>
+				<div class="block">
+					<span class="text-xs font-medium text-gray-700"
+						>Default section <span class="text-gray-400">(optional)</span></span
+					>
+					<div class="mt-1">
+						<TextCombobox
+							bind:value={formDefaultSection}
+							suggestions={typicalSections}
+							placeholder="e.g. Produce"
+							ariaLabel="Default section"
+							inputClass="field w-full"
+						/>
+					</div>
+					<span class="mt-0.5 block text-xs text-gray-400">
+						Used to slot this item into the matching section at each store. Pick a common
+						name or type your own.
+					</span>
+				</div>
 				<fieldset>
 					<legend class="text-xs font-medium text-gray-700">Allowed units</legend>
 					<p class="mt-0.5 text-xs text-gray-400">Leave all unchecked to allow any unit.</p>