Add region code

Distribution/Migrations/20261006100000_AddRegionCode.cs

@@ -0,0 +1,54 @@
+using Distribution.Data;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Distribution.Migrations
+{
+    /// <inheritdoc />
+    [DbContext(typeof(AppDBContext))]
+    [Migration("20261006100000_AddRegionCode")]
+    public partial class AddRegionCode : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "Code",
+                table: "Regions",
+                type: "varchar(50)",
+                maxLength: 50,
+                nullable: false,
+                defaultValue: "");
+
+            // Backfill existing rows (seeded regions first) with REG-0001, REG-0002, ... before the unique index.
+            migrationBuilder.Sql(@"
+                UPDATE `Regions` r
+                JOIN (
+                    SELECT `Id`, ROW_NUMBER() OVER (
+                        ORDER BY CASE WHEN `Id` LIKE '24000000-%' THEN 0 ELSE 1 END, `CreatedAt`, `Id`) AS rn
+                    FROM `Regions`
+                ) x ON r.`Id` = x.`Id`
+                SET r.`Code` = CONCAT('REG-', LPAD(x.rn, 4, '0'));");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Regions_Code",
+                table: "Regions",
+                column: "Code",
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Regions_Code",
+                table: "Regions");
+
+            migrationBuilder.DropColumn(
+                name: "Code",
+                table: "Regions");
+        }
+    }
+}

Distribution/Migrations/AppDBContextModelSnapshot.cs

@@ -1474,6 +1474,11 @@ namespace Distribution.Migrations
                         .ValueGeneratedOnAdd()
                         .HasColumnType("char(36)");
 
+                    b.Property<string>("Code")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("varchar(50)");
+
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("datetime(6)");
 
@@ -1486,6 +1491,9 @@ namespace Distribution.Migrations
 
                     b.HasKey("Id");
 
+                    b.HasIndex("Code")
+                        .IsUnique();
+
                     b.ToTable("Regions");
 
                     b.HasData(
@@ -1494,6 +1502,7 @@ namespace Distribution.Migrations
                             Id = new Guid("24000000-0000-0000-0000-000000000001"),
                             CreatedAt = new DateTime(2026, 8, 20, 0, 0, 0, 0, DateTimeKind.Unspecified),
                             IsActive = true,
+                            Code = "REG-0001",
                             Name = "Western Province"
                         },
                         new
@@ -1501,6 +1510,7 @@ namespace Distribution.Migrations
                             Id = new Guid("24000000-0000-0000-0000-000000000002"),
                             CreatedAt = new DateTime(2026, 8, 20, 0, 0, 0, 0, DateTimeKind.Unspecified),
                             IsActive = true,
+                            Code = "REG-0002",
                             Name = "Central Province"
                         });
                 });