CW-STORY-05.2: model purchases and purchase items

Purchase (aggregate root) and PurchaseItem per AGENTS.md §5.6.
AddItem composition + tightened PurchaseItem ctor deferred to
CW-STORY-05.4, mirroring the CW-STORY-03.1/03.3 split.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.claude/settings.json

@@ -37,7 +37,8 @@
       "Bash(curl -s -b /tmp/cw5.txt -m 15 http://127.0.0.1:5187/api/products/barcode/3017620422003)",
       "Bash(curl -s -b /tmp/cw5.txt http://127.0.0.1:5187/products/0ce5df7a-6c8d-489d-ba9f-8d41699f0705 -o /tmp/product.html -w \"status=%{http_code}\\\\n\")",
       "Bash(sed -n '/<h1>/,/Add to my list/p' /tmp/product.html)",
-      "Bash(cd \"g:/development/C Sharp AI/CartWise\" && rm -f verify4.db* && dotnet ef database update --project src/CartWise.Infrastructure/CartWise.Infrastructure.csproj --startup-project src/CartWise.Web/CartWise.Web.csproj --connection \"Data Source=verify4.db\" 2>&1 | tail -10 && rm -f verify4.db*)"
+      "Bash(cd \"g:/development/C Sharp AI/CartWise\" && rm -f verify4.db* && dotnet ef database update --project src/CartWise.Infrastructure/CartWise.Infrastructure.csproj --startup-project src/CartWise.Web/CartWise.Web.csproj --connection \"Data Source=verify4.db\" 2>&1 | tail -10 && rm -f verify4.db*)",
+      "Bash(cd \"g:/development/C Sharp AI/CartWise\" && rm -f verify5.db* && dotnet ef database update --project src/CartWise.Infrastructure/CartWise.Infrastructure.csproj --startup-project src/CartWise.Web/CartWise.Web.csproj --connection \"Data Source=verify5.db\" 2>&1 | tail -10 && rm -f verify5.db*)"
     ],
     "additionalDirectories": [
       "G:\\development\\C Sharp AI\\CartWise"

docs/scrum-backlog.md

@@ -573,12 +573,14 @@ Verified live end-to-end with a **real** barcode against the **real** Open Food
 - EF configurations and migration are created
 
 **Tasks**
-- [ ] Create `Purchase`
-- [ ] Create `PurchaseItem`
-- [ ] Add source type enum
-- [ ] Add EF configurations
-- [ ] Create migration
-- [ ] Add tests
+- [x] Create `Purchase`
+- [x] Create `PurchaseItem`
+- [x] Add source type enum
+- [x] Add EF configurations
+- [x] Create migration
+- [x] Add tests
+
+**Status:** Done — `Purchase` is the aggregate root for `PurchaseItem`, mirroring `ShoppingList`/`ShoppingListItem`'s split across stories: `Items` navigation exists now, but no `AddItem` composition method yet and `PurchaseItem`'s constructor stays `public` — both arrive in `CW-STORY-05.4` when the service layer actually needs them, exactly matching the `CW-STORY-03.1`→`03.3` precedent. `PurchaseSourceType` (`Manual`/`ShoppingMode`/`ReceiptImport`/`RetailerImport`) added. `PurchaseItem` enforces `Quantity > 0` and `LinePrice >= 0` as constructor invariants. `AddPurchases` migration verified applying cleanly. 11 domain tests.
 
 ### `CW-STORY-05.3` Model append-only price observations
 **Release:** MVP  

src/CartWise.Domain/Entities/Purchase.cs

@@ -0,0 +1,61 @@
+using CartWise.Domain.Enums;
+
+namespace CartWise.Domain.Entities;
+
+public class Purchase
+{
+    private readonly List<PurchaseItem> _items = [];
+
+    public Guid PurchaseId { get; private set; }
+
+    public Guid HouseholdId { get; private set; }
+
+    public Guid? StoreLocationId { get; private set; }
+
+    public string PurchasedByUserId { get; private set; } = null!;
+
+    public DateTime PurchasedUtc { get; private set; }
+
+    public decimal? Subtotal { get; private set; }
+
+    public decimal? Tax { get; private set; }
+
+    public decimal? Total { get; private set; }
+
+    public PurchaseSourceType SourceType { get; private set; }
+
+    public DateTime CreatedUtc { get; private set; }
+
+    public IReadOnlyCollection<PurchaseItem> Items => _items.AsReadOnly();
+
+    private Purchase()
+    {
+    }
+
+    public Purchase(
+        Guid householdId,
+        string purchasedByUserId,
+        DateTime purchasedUtc,
+        DateTime createdUtc,
+        PurchaseSourceType sourceType = PurchaseSourceType.Manual,
+        Guid? storeLocationId = null)
+    {
+        if (householdId == Guid.Empty)
+        {
+            throw new ArgumentException("HouseholdId is required.", nameof(householdId));
+        }
+
+        if (string.IsNullOrWhiteSpace(purchasedByUserId))
+        {
+            throw new ArgumentException("PurchasedByUserId is required.", nameof(purchasedByUserId));
+        }
+
+        PurchaseId = Guid.NewGuid();
+        HouseholdId = householdId;
+        StoreLocationId = storeLocationId;
+        PurchasedByUserId = purchasedByUserId;
+        PurchasedUtc = purchasedUtc;
+        SourceType = sourceType;
+        CreatedUtc = createdUtc;
+    }
+}

src/CartWise.Domain/Entities/PurchaseItem.cs

@@ -0,0 +1,75 @@
+namespace CartWise.Domain.Entities;
+
+public class PurchaseItem
+{
+    public Guid PurchaseItemId { get; private set; }
+
+    public Guid PurchaseId { get; private set; }
+
+    public Guid? ProductId { get; private set; }
+
+    public Guid? GroceryConceptId { get; private set; }
+
+    public Guid? ShoppingListItemId { get; private set; }
+
+    public string Description { get; private set; } = null!;
+
+    public decimal Quantity { get; private set; }
+
+    public string? Unit { get; private set; }
+
+    public decimal LinePrice { get; private set; }
+
+    public decimal? UnitPrice { get; private set; }
+
+    public DateTime CreatedUtc { get; private set; }
+
+    private PurchaseItem()
+    {
+    }
+
+    public PurchaseItem(
+        Guid purchaseId,
+        string description,
+        decimal linePrice,
+        DateTime createdUtc,
+        decimal quantity = 1m,
+        string? unit = null,
+        Guid? productId = null,
+        Guid? groceryConceptId = null,
+        Guid? shoppingListItemId = null,
+        decimal? unitPrice = null)
+    {
+        if (purchaseId == Guid.Empty)
+        {
+            throw new ArgumentException("PurchaseId is required.", nameof(purchaseId));
+        }
+
+        if (string.IsNullOrWhiteSpace(description))
+        {
+            throw new ArgumentException("Description is required.", nameof(description));
+        }
+
+        if (quantity <= 0)
+        {
+            throw new ArgumentOutOfRangeException(nameof(quantity), "Quantity must be greater than zero.");
+        }
+
+        if (linePrice < 0)
+        {
+            throw new ArgumentOutOfRangeException(nameof(linePrice), "LinePrice cannot be negative.");
+        }
+
+        PurchaseItemId = Guid.NewGuid();
+        PurchaseId = purchaseId;
+        Description = description.Trim();
+        Quantity = quantity;
+        Unit = unit;
+        LinePrice = linePrice;
+        UnitPrice = unitPrice;
+        ProductId = productId;
+        GroceryConceptId = groceryConceptId;
+        ShoppingListItemId = shoppingListItemId;
+        CreatedUtc = createdUtc;
+    }
+}

src/CartWise.Domain/Enums/PurchaseSourceType.cs

@@ -0,0 +1,9 @@
+namespace CartWise.Domain.Enums;
+
+public enum PurchaseSourceType
+{
+    Manual = 0,
+    ShoppingMode = 1,
+    ReceiptImport = 2,
+    RetailerImport = 3
+}

src/CartWise.Infrastructure/Data/CartWiseDbContext.cs

@@ -37,6 +37,10 @@ public class CartWiseDbContext : IdentityDbContext<ApplicationUser>, IApplicatio
 
     public DbSet<StoreLocation> StoreLocations => Set<StoreLocation>();
 
+    public DbSet<Purchase> Purchases => Set<Purchase>();
+
+    public DbSet<PurchaseItem> PurchaseItems => Set<PurchaseItem>();
+
     protected override void OnModelCreating(ModelBuilder builder)
     {
         base.OnModelCreating(builder);

src/CartWise.Infrastructure/Data/Configurations/PurchaseConfiguration.cs

@@ -0,0 +1,34 @@
+using CartWise.Domain.Entities;
+using CartWise.Infrastructure.Identity;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace CartWise.Infrastructure.Data.Configurations;
+
+public class PurchaseConfiguration : IEntityTypeConfiguration<Purchase>
+{
+    public void Configure(EntityTypeBuilder<Purchase> builder)
+    {
+        builder.HasKey(p => p.PurchaseId);
+
+        builder.HasOne<Household>()
+            .WithMany()
+            .HasForeignKey(p => p.HouseholdId)
+            .OnDelete(DeleteBehavior.Cascade);
+
+        builder.HasOne<StoreLocation>()
+            .WithMany()
+            .HasForeignKey(p => p.StoreLocationId)
+            .OnDelete(DeleteBehavior.SetNull);
+
+        builder.HasOne<ApplicationUser>()
+            .WithMany()
+            .HasForeignKey(p => p.PurchasedByUserId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasIndex(p => new { p.HouseholdId, p.PurchasedUtc });
+
+        builder.Metadata.FindNavigation(nameof(Purchase.Items))!
+            .SetPropertyAccessMode(PropertyAccessMode.Field);
+    }
+}

src/CartWise.Infrastructure/Data/Configurations/PurchaseItemConfiguration.cs

@@ -0,0 +1,41 @@
+using CartWise.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace CartWise.Infrastructure.Data.Configurations;
+
+public class PurchaseItemConfiguration : IEntityTypeConfiguration<PurchaseItem>
+{
+    public void Configure(EntityTypeBuilder<PurchaseItem> builder)
+    {
+        builder.HasKey(i => i.PurchaseItemId);
+
+        builder.Property(i => i.Description)
+            .HasMaxLength(240)
+            .IsRequired();
+
+        builder.Property(i => i.Unit).HasMaxLength(32);
+
+        builder.HasOne<Purchase>()
+            .WithMany(p => p.Items)
+            .HasForeignKey(i => i.PurchaseId)
+            .OnDelete(DeleteBehavior.Cascade);
+
+        builder.HasOne<Product>()
+            .WithMany()
+            .HasForeignKey(i => i.ProductId)
+            .OnDelete(DeleteBehavior.SetNull);
+
+        builder.HasOne<GroceryConcept>()
+            .WithMany()
+            .HasForeignKey(i => i.GroceryConceptId)
+            .OnDelete(DeleteBehavior.SetNull);
+
+        builder.HasOne<ShoppingListItem>()
+            .WithMany()
+            .HasForeignKey(i => i.ShoppingListItemId)
+            .OnDelete(DeleteBehavior.SetNull);
+
+        builder.HasIndex(i => i.ProductId);
+    }
+}

src/CartWise.Infrastructure/Data/Migrations/20260810191555_AddPurchases.Designer.cs

@@ -0,0 +1,996 @@
+// <auto-generated />
+using System;
+using CartWise.Infrastructure.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace CartWise.Infrastructure.Data.Migrations
+{
+    [DbContext(typeof(CartWiseDbContext))]
+    [Migration("20260810191555_AddPurchases")]
+    partial class AddPurchases
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "10.0.10");
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Brand", b =>
+                {
+                    b.Property<Guid>("BrandId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("BrandId");
+
+                    b.HasIndex("NormalizedName")
+                        .IsUnique();
+
+                    b.ToTable("Brands");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.GroceryConcept", b =>
+                {
+                    b.Property<Guid>("GroceryConceptId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("CategoryId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("GroceryConceptId");
+
+                    b.HasIndex("CategoryId");
+
+                    b.HasIndex("NormalizedName")
+                        .IsUnique();
+
+                    b.ToTable("GroceryConcepts");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Household", b =>
+                {
+                    b.Property<Guid>("HouseholdId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("CreatedByUserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(120)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("HouseholdId");
+
+                    b.HasIndex("CreatedByUserId");
+
+                    b.ToTable("Households");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.HouseholdMember", b =>
+                {
+                    b.Property<Guid>("HouseholdId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("JoinedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("Role")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("HouseholdId", "UserId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("HouseholdMembers");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.HouseholdProductPreference", b =>
+                {
+                    b.Property<Guid>("HouseholdProductPreferenceId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("GroceryConceptId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("HouseholdId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("PreferredProductId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("PreferredQuantity")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PreferredUnit")
+                        .HasMaxLength(32)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("SubstitutionLevel")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<DateTime>("UpdatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("HouseholdProductPreferenceId");
+
+                    b.HasIndex("GroceryConceptId");
+
+                    b.HasIndex("PreferredProductId");
+
+                    b.HasIndex("HouseholdId", "GroceryConceptId")
+                        .IsUnique();
+
+                    b.ToTable("HouseholdProductPreferences");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Product", b =>
+                {
+                    b.Property<Guid>("ProductId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("BrandId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("GroceryConceptId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ImageUrl")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(240)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(240)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("SizeUnit")
+                        .HasMaxLength(32)
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("SizeValue")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("SourceExternalId")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("SourceType")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<DateTime>("UpdatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("ProductId");
+
+                    b.HasIndex("BrandId");
+
+                    b.HasIndex("GroceryConceptId");
+
+                    b.HasIndex("NormalizedName");
+
+                    b.ToTable("Products");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ProductCategory", b =>
+                {
+                    b.Property<Guid>("ProductCategoryId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("ParentCategoryId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("ProductCategoryId");
+
+                    b.HasIndex("ParentCategoryId");
+
+                    b.ToTable("ProductCategories");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ProductIdentifier", b =>
+                {
+                    b.Property<Guid>("ProductIdentifierId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("IdentifierType")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("NormalizedValue")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("ProductId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Value")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("ProductIdentifierId");
+
+                    b.HasIndex("ProductId");
+
+                    b.HasIndex("IdentifierType", "NormalizedValue")
+                        .IsUnique();
+
+                    b.ToTable("ProductIdentifiers");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Purchase", b =>
+                {
+                    b.Property<Guid>("PurchaseId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("HouseholdId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PurchasedByUserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("PurchasedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("SourceType")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<Guid?>("StoreLocationId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Subtotal")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Tax")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Total")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("PurchaseId");
+
+                    b.HasIndex("PurchasedByUserId");
+
+                    b.HasIndex("StoreLocationId");
+
+                    b.HasIndex("HouseholdId", "PurchasedUtc");
+
+                    b.ToTable("Purchases");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.PurchaseItem", b =>
+                {
+                    b.Property<Guid>("PurchaseItemId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Description")
+                        .IsRequired()
+                        .HasMaxLength(240)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("GroceryConceptId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("LinePrice")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("ProductId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("PurchaseId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("Quantity")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("ShoppingListItemId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Unit")
+                        .HasMaxLength(32)
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("UnitPrice")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("PurchaseItemId");
+
+                    b.HasIndex("GroceryConceptId");
+
+                    b.HasIndex("ProductId");
+
+                    b.HasIndex("PurchaseId");
+
+                    b.HasIndex("ShoppingListItemId");
+
+                    b.ToTable("PurchaseItems");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Retailer", b =>
+                {
+                    b.Property<Guid>("RetailerId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("WebsiteUrl")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("RetailerId");
+
+                    b.HasIndex("NormalizedName")
+                        .IsUnique();
+
+                    b.ToTable("Retailers");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ShoppingList", b =>
+                {
+                    b.Property<Guid>("ShoppingListId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime?>("CompletedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("CreatedByUserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("HouseholdId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(160)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("Status")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("ShoppingListId");
+
+                    b.HasIndex("CreatedByUserId");
+
+                    b.HasIndex("HouseholdId", "Status");
+
+                    b.ToTable("ShoppingLists");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ShoppingListItem", b =>
+                {
+                    b.Property<Guid>("ShoppingListItemId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("AddedByUserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("AddedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("DisplayName")
+                        .IsRequired()
+                        .HasMaxLength(240)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("GroceryConceptId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Notes")
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime?>("PurchasedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Quantity")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("RowVersion")
+                        .IsConcurrencyToken()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("ShoppingListId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("SortOrder")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<int>("Status")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("Unit")
+                        .HasMaxLength(32)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("ShoppingListItemId");
+
+                    b.HasIndex("AddedByUserId");
+
+                    b.HasIndex("GroceryConceptId");
+
+                    b.HasIndex("ShoppingListId", "Status");
+
+                    b.ToTable("ShoppingListItems");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.StoreLocation", b =>
+                {
+                    b.Property<Guid>("StoreLocationId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("AddressLine1")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("AddressLine2")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("City")
+                        .HasMaxLength(120)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("CountryCode")
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ExternalStoreId")
+                        .HasMaxLength(120)
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Latitude")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Longitude")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PostalCode")
+                        .HasMaxLength(24)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Region")
+                        .HasMaxLength(80)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("RetailerId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("UpdatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("StoreLocationId");
+
+                    b.HasIndex("RetailerId");
+
+                    b.ToTable("StoreLocations");
+                });
+
+            modelBuilder.Entity("CartWise.Infrastructure.Identity.ApplicationUser", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AccessFailedCount")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("ConcurrencyStamp")
+                        .IsConcurrencyToken()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("DisplayName")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Email")
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("EmailConfirmed")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<bool>("LockoutEnabled")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<DateTimeOffset?>("LockoutEnd")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedEmail")
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedUserName")
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PasswordHash")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PhoneNumber")
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("PhoneNumberConfirmed")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("SecurityStamp")
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("TwoFactorEnabled")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("UserName")
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("NormalizedEmail")
+                        .HasDatabaseName("EmailIndex");
+
+                    b.HasIndex("NormalizedUserName")
+                        .IsUnique()
+                        .HasDatabaseName("UserNameIndex");
+
+                    b.ToTable("AspNetUsers", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRole", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ConcurrencyStamp")
+                        .IsConcurrencyToken()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedName")
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("RoleNameIndex");
+
+                    b.ToTable("AspNetRoles", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<string>", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("ClaimType")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ClaimValue")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("RoleId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("RoleId");
+
+                    b.ToTable("AspNetRoleClaims", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserClaim<string>", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("ClaimType")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ClaimValue")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("UserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("AspNetUserClaims", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserLogin<string>", b =>
+                {
+                    b.Property<string>("LoginProvider")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ProviderKey")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ProviderDisplayName")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("UserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("LoginProvider", "ProviderKey");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("AspNetUserLogins", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserRole<string>", b =>
+                {
+                    b.Property<string>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("RoleId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("UserId", "RoleId");
+
+                    b.HasIndex("RoleId");
+
+                    b.ToTable("AspNetUserRoles", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserToken<string>", b =>
+                {
+                    b.Property<string>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("LoginProvider")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Value")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("UserId", "LoginProvider", "Name");
+
+                    b.ToTable("AspNetUserTokens", (string)null);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.GroceryConcept", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.ProductCategory", null)
+                        .WithMany()
+                        .HasForeignKey("CategoryId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Household", b =>
+                {
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("CreatedByUserId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.HouseholdMember", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.Household", null)
+                        .WithMany("Members")
+                        .HasForeignKey("HouseholdId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.HouseholdProductPreference", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.GroceryConcept", null)
+                        .WithMany()
+                        .HasForeignKey("GroceryConceptId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.Household", null)
+                        .WithMany()
+                        .HasForeignKey("HouseholdId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.Product", null)
+                        .WithMany()
+                        .HasForeignKey("PreferredProductId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Product", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.Brand", null)
+                        .WithMany()
+                        .HasForeignKey("BrandId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("CartWise.Domain.Entities.GroceryConcept", null)
+                        .WithMany()
+                        .HasForeignKey("GroceryConceptId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ProductCategory", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.ProductCategory", null)
+                        .WithMany()
+                        .HasForeignKey("ParentCategoryId")
+                        .OnDelete(DeleteBehavior.Restrict);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ProductIdentifier", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.Product", null)
+                        .WithMany("Identifiers")
+                        .HasForeignKey("ProductId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Purchase", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.Household", null)
+                        .WithMany()
+                        .HasForeignKey("HouseholdId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("PurchasedByUserId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.StoreLocation", null)
+                        .WithMany()
+                        .HasForeignKey("StoreLocationId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.PurchaseItem", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.GroceryConcept", null)
+                        .WithMany()
+                        .HasForeignKey("GroceryConceptId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("CartWise.Domain.Entities.Product", null)
+                        .WithMany()
+                        .HasForeignKey("ProductId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("CartWise.Domain.Entities.Purchase", null)
+                        .WithMany("Items")
+                        .HasForeignKey("PurchaseId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.ShoppingListItem", null)
+                        .WithMany()
+                        .HasForeignKey("ShoppingListItemId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ShoppingList", b =>
+                {
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("CreatedByUserId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.Household", null)
+                        .WithMany()
+                        .HasForeignKey("HouseholdId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ShoppingListItem", b =>
+                {
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("AddedByUserId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.GroceryConcept", null)
+                        .WithMany()
+                        .HasForeignKey("GroceryConceptId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("CartWise.Domain.Entities.ShoppingList", null)
+                        .WithMany("Items")
+                        .HasForeignKey("ShoppingListId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.StoreLocation", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.Retailer", null)
+                        .WithMany()
+                        .HasForeignKey("RetailerId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<string>", b =>
+                {
+                    b.HasOne("Microsoft.AspNetCore.Identity.IdentityRole", null)
+                        .WithMany()
+                        .HasForeignKey("RoleId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserClaim<string>", b =>
+                {
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserLogin<string>", b =>
+                {
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserRole<string>", b =>
+                {
+                    b.HasOne("Microsoft.AspNetCore.Identity.IdentityRole", null)
+                        .WithMany()
+                        .HasForeignKey("RoleId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserToken<string>", b =>
+                {
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Household", b =>
+                {
+                    b.Navigation("Members");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Product", b =>
+                {
+                    b.Navigation("Identifiers");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.Purchase", b =>
+                {
+                    b.Navigation("Items");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.ShoppingList", b =>
+                {
+                    b.Navigation("Items");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

src/CartWise.Infrastructure/Data/Migrations/20260810191555_AddPurchases.cs

@@ -0,0 +1,143 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace CartWise.Infrastructure.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddPurchases : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Purchases",
+                columns: table => new
+                {
+                    PurchaseId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    HouseholdId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    StoreLocationId = table.Column<Guid>(type: "TEXT", nullable: true),
+                    PurchasedByUserId = table.Column<string>(type: "TEXT", nullable: false),
+                    PurchasedUtc = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    Subtotal = table.Column<decimal>(type: "TEXT", nullable: true),
+                    Tax = table.Column<decimal>(type: "TEXT", nullable: true),
+                    Total = table.Column<decimal>(type: "TEXT", nullable: true),
+                    SourceType = table.Column<int>(type: "INTEGER", nullable: false),
+                    CreatedUtc = table.Column<DateTime>(type: "TEXT", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Purchases", x => x.PurchaseId);
+                    table.ForeignKey(
+                        name: "FK_Purchases_AspNetUsers_PurchasedByUserId",
+                        column: x => x.PurchasedByUserId,
+                        principalTable: "AspNetUsers",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                    table.ForeignKey(
+                        name: "FK_Purchases_Households_HouseholdId",
+                        column: x => x.HouseholdId,
+                        principalTable: "Households",
+                        principalColumn: "HouseholdId",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_Purchases_StoreLocations_StoreLocationId",
+                        column: x => x.StoreLocationId,
+                        principalTable: "StoreLocations",
+                        principalColumn: "StoreLocationId",
+                        onDelete: ReferentialAction.SetNull);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "PurchaseItems",
+                columns: table => new
+                {
+                    PurchaseItemId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    PurchaseId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    ProductId = table.Column<Guid>(type: "TEXT", nullable: true),
+                    GroceryConceptId = table.Column<Guid>(type: "TEXT", nullable: true),
+                    ShoppingListItemId = table.Column<Guid>(type: "TEXT", nullable: true),
+                    Description = table.Column<string>(type: "TEXT", maxLength: 240, nullable: false),
+                    Quantity = table.Column<decimal>(type: "TEXT", nullable: false),
+                    Unit = table.Column<string>(type: "TEXT", maxLength: 32, nullable: true),
+                    LinePrice = table.Column<decimal>(type: "TEXT", nullable: false),
+                    UnitPrice = table.Column<decimal>(type: "TEXT", nullable: true),
+                    CreatedUtc = table.Column<DateTime>(type: "TEXT", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_PurchaseItems", x => x.PurchaseItemId);
+                    table.ForeignKey(
+                        name: "FK_PurchaseItems_GroceryConcepts_GroceryConceptId",
+                        column: x => x.GroceryConceptId,
+                        principalTable: "GroceryConcepts",
+                        principalColumn: "GroceryConceptId",
+                        onDelete: ReferentialAction.SetNull);
+                    table.ForeignKey(
+                        name: "FK_PurchaseItems_Products_ProductId",
+                        column: x => x.ProductId,
+                        principalTable: "Products",
+                        principalColumn: "ProductId",
+                        onDelete: ReferentialAction.SetNull);
+                    table.ForeignKey(
+                        name: "FK_PurchaseItems_Purchases_PurchaseId",
+                        column: x => x.PurchaseId,
+                        principalTable: "Purchases",
+                        principalColumn: "PurchaseId",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_PurchaseItems_ShoppingListItems_ShoppingListItemId",
+                        column: x => x.ShoppingListItemId,
+                        principalTable: "ShoppingListItems",
+                        principalColumn: "ShoppingListItemId",
+                        onDelete: ReferentialAction.SetNull);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_PurchaseItems_GroceryConceptId",
+                table: "PurchaseItems",
+                column: "GroceryConceptId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_PurchaseItems_ProductId",
+                table: "PurchaseItems",
+                column: "ProductId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_PurchaseItems_PurchaseId",
+                table: "PurchaseItems",
+                column: "PurchaseId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_PurchaseItems_ShoppingListItemId",
+                table: "PurchaseItems",
+                column: "ShoppingListItemId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Purchases_HouseholdId_PurchasedUtc",
+                table: "Purchases",
+                columns: new[] { "HouseholdId", "PurchasedUtc" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Purchases_PurchasedByUserId",
+                table: "Purchases",
+                column: "PurchasedByUserId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Purchases_StoreLocationId",
+                table: "Purchases",
+                column: "StoreLocationId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "PurchaseItems");
+
+            migrationBuilder.DropTable(
+                name: "Purchases");
+        }
+    }
+}

src/CartWise.Infrastructure/Data/Migrations/CartWiseDbContextModelSnapshot.cs

@@ -268,6 +268,103 @@ namespace CartWise.Infrastructure.Data.Migrations
                     b.ToTable("ProductIdentifiers");
                 });
 
+            modelBuilder.Entity("CartWise.Domain.Entities.Purchase", b =>
+                {
+                    b.Property<Guid>("PurchaseId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("HouseholdId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PurchasedByUserId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("PurchasedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("SourceType")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<Guid?>("StoreLocationId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Subtotal")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Tax")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("Total")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("PurchaseId");
+
+                    b.HasIndex("PurchasedByUserId");
+
+                    b.HasIndex("StoreLocationId");
+
+                    b.HasIndex("HouseholdId", "PurchasedUtc");
+
+                    b.ToTable("Purchases");
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.PurchaseItem", b =>
+                {
+                    b.Property<Guid>("PurchaseItemId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Description")
+                        .IsRequired()
+                        .HasMaxLength(240)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("GroceryConceptId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("LinePrice")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("ProductId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("PurchaseId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("Quantity")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("ShoppingListItemId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Unit")
+                        .HasMaxLength(32)
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal?>("UnitPrice")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("PurchaseItemId");
+
+                    b.HasIndex("GroceryConceptId");
+
+                    b.HasIndex("ProductId");
+
+                    b.HasIndex("PurchaseId");
+
+                    b.HasIndex("ShoppingListItemId");
+
+                    b.ToTable("PurchaseItems");
+                });
+
             modelBuilder.Entity("CartWise.Domain.Entities.Retailer", b =>
                 {
                     b.Property<Guid>("RetailerId")
@@ -732,6 +829,50 @@ namespace CartWise.Infrastructure.Data.Migrations
                         .IsRequired();
                 });
 
+            modelBuilder.Entity("CartWise.Domain.Entities.Purchase", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.Household", null)
+                        .WithMany()
+                        .HasForeignKey("HouseholdId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("PurchasedByUserId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.StoreLocation", null)
+                        .WithMany()
+                        .HasForeignKey("StoreLocationId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
+            modelBuilder.Entity("CartWise.Domain.Entities.PurchaseItem", b =>
+                {
+                    b.HasOne("CartWise.Domain.Entities.GroceryConcept", null)
+                        .WithMany()
+                        .HasForeignKey("GroceryConceptId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("CartWise.Domain.Entities.Product", null)
+                        .WithMany()
+                        .HasForeignKey("ProductId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("CartWise.Domain.Entities.Purchase", null)
+                        .WithMany("Items")
+                        .HasForeignKey("PurchaseId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("CartWise.Domain.Entities.ShoppingListItem", null)
+                        .WithMany()
+                        .HasForeignKey("ShoppingListItemId")
+                        .OnDelete(DeleteBehavior.SetNull);
+                });
+
             modelBuilder.Entity("CartWise.Domain.Entities.ShoppingList", b =>
                 {
                     b.HasOne("CartWise.Infrastructure.Identity.ApplicationUser", null)
@@ -837,6 +978,11 @@ namespace CartWise.Infrastructure.Data.Migrations
                     b.Navigation("Identifiers");
                 });
 
+            modelBuilder.Entity("CartWise.Domain.Entities.Purchase", b =>
+                {
+                    b.Navigation("Items");
+                });
+
             modelBuilder.Entity("CartWise.Domain.Entities.ShoppingList", b =>
                 {
                     b.Navigation("Items");

tests/CartWise.Domain.Tests/PurchaseTests.cs

@@ -0,0 +1,70 @@
+using CartWise.Domain.Entities;
+using CartWise.Domain.Enums;
+
+namespace CartWise.Domain.Tests;
+
+public class PurchaseTests
+{
+    private static readonly DateTime Now = new(2026, 8, 10, 12, 0, 0, DateTimeKind.Utc);
+
+    [Fact]
+    public void Constructor_DefaultsToManualSourceAndNoStore()
+    {
+        var purchase = new Purchase(Guid.NewGuid(), "user-1", Now, Now);
+
+        Assert.Equal(PurchaseSourceType.Manual, purchase.SourceType);
+        Assert.Null(purchase.StoreLocationId);
+        Assert.Empty(purchase.Items);
+    }
+
+    [Fact]
+    public void Constructor_ThrowsWhenHouseholdIdIsEmpty()
+    {
+        Assert.Throws<ArgumentException>(() => new Purchase(Guid.Empty, "user-1", Now, Now));
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData(null)]
+    public void Constructor_ThrowsWhenPurchasedByUserIdIsMissing(string? userId)
+    {
+        Assert.Throws<ArgumentException>(() => new Purchase(Guid.NewGuid(), userId!, Now, Now));
+    }
+}
+
+public class PurchaseItemTests
+{
+    private static readonly DateTime Now = new(2026, 8, 10, 12, 0, 0, DateTimeKind.Utc);
+
+    [Fact]
+    public void Constructor_DefaultsQuantityToOne()
+    {
+        var item = new PurchaseItem(Guid.NewGuid(), "Milk", 3.99m, Now);
+
+        Assert.Equal(1m, item.Quantity);
+        Assert.Equal(3.99m, item.LinePrice);
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData(null)]
+    public void Constructor_ThrowsWhenDescriptionIsMissing(string? description)
+    {
+        Assert.Throws<ArgumentException>(() => new PurchaseItem(Guid.NewGuid(), description!, 3.99m, Now));
+    }
+
+    [Fact]
+    public void Constructor_ThrowsWhenQuantityIsZeroOrNegative()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new PurchaseItem(Guid.NewGuid(), "Milk", 3.99m, Now, quantity: 0));
+        Assert.Throws<ArgumentOutOfRangeException>(() => new PurchaseItem(Guid.NewGuid(), "Milk", 3.99m, Now, quantity: -1));
+    }
+
+    [Fact]
+    public void Constructor_ThrowsWhenLinePriceIsNegative()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new PurchaseItem(Guid.NewGuid(), "Milk", -1m, Now));
+    }
+}