notification module

Backend/ERPCore/Controllers/NotificationConfigController.cs

@@ -0,0 +1,34 @@
+using ERPCore.Dtos.Notifications;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+[Route("api/v1/notification-config")]
+public sealed class NotificationConfigController : ApiControllerBase
+{
+    private readonly INotificationConfigService _config;
+
+    public NotificationConfigController(INotificationConfigService config) => _config = config;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(NotificationConfigDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<NotificationConfigDto>> Get(CancellationToken ct)
+    {
+        var result = await _config.GetAsync(ct);
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpPut]
+    [ProducesResponseType(typeof(NotificationConfigDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status412PreconditionFailed)]
+    public async Task<ActionResult<NotificationConfigDto>> Update([FromBody] UpdateNotificationConfigRequest request, CancellationToken ct)
+    {
+        var expected = RequireIfMatch();
+        var result = await _config.UpdateAsync(request, expected, ct);
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+}

Backend/ERPCore/Domain/Entities/NotificationConfig.cs

@@ -0,0 +1,19 @@
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// Notification configuration (new settings module) - singleton root row.
+/// </summary>
+public class NotificationConfig
+{
+    public const int SingletonId = 1;
+
+    public int NotificationConfigId { get; set; }
+
+    public DateTime? UpdatedAt { get; set; }
+    public int? UpdatedBy { get; set; }
+    public User? UpdatedByUser { get; set; }
+
+    public uint RowVersion { get; set; }
+
+    public ICollection<NotificationConfigModule> Modules { get; set; } = new List<NotificationConfigModule>();
+}

Backend/ERPCore/Domain/Entities/NotificationConfigModule.cs

@@ -0,0 +1,14 @@
+namespace ERPCore.Domain.Entities;
+
+public class NotificationConfigModule
+{
+    public int NotificationConfigModuleId { get; set; }
+
+    public int NotificationConfigId { get; set; }
+    public NotificationConfig? NotificationConfig { get; set; }
+
+    public string ModuleKey { get; set; } = string.Empty;
+    public bool EmailEnabled { get; set; }
+    public bool SmsEnabled { get; set; }
+    public bool InAppEnabled { get; set; }
+}

Backend/ERPCore/Domain/Entities/ProductConfig.cs

@@ -1,22 +1,24 @@
 namespace ERPCore.Domain.Entities;
 
 /// <summary>
-/// Product configuration (FR-MD-11) — a <b>singleton row</b> (single-tenant, docs/00-CORE §1)
+/// Product configuration (FR-MD-11) - a singleton row (single-tenant, docs/00-CORE §1)
 /// gating optional product master-data features.
 /// <para>
 /// <see cref="SubcategoriesEnabled"/> and <see cref="BrandsEnabled"/> are enforced
 /// server-side: an Item write carrying a subcategory/brand while the flag is off is
-/// rejected with <c>CONFIG_DISABLED</c>. <see cref="ItemTypesEnabled"/> is
-/// <b>advisory only</b> — items carry no item-type reference (see <see cref="ItemType"/>),
-/// so there is nothing on a write to reject; the frontend honours it by hiding the
-/// builder's type section. Reads are never gated, so existing data stays visible after a
-/// flag is switched off.
+/// rejected with <c>CONFIG_DISABLED</c>. <see cref="ItemTypesEnabled"/> is advisory only
+/// - items carry no item-type reference (see <see cref="ItemType"/>), so there is nothing
+/// on a write to reject; the frontend honours it by hiding the variant builder.
+/// <see cref="SellingPricesEnabled"/>, <see cref="SerialNumbersEnabled"/>,
+/// <see cref="BatchListsEnabled"/> and <see cref="WarrantyPeriodsEnabled"/> are enforced
+/// on item writes and drive the create/edit screens. Reads are never gated, so existing
+/// data stays visible after a flag is switched off.
 /// </para>
 /// Model: docs/10-BACKEND-PHASE1.md Part C.1.
 /// </summary>
 public class ProductConfig
 {
-    /// <summary>Always 1 — the singleton row's id.</summary>
+    /// <summary>Always 1 - the singleton row's id.</summary>
     public const int SingletonId = 1;
 
     public int ConfigId { get; set; }
@@ -24,6 +26,10 @@ public class ProductConfig
     public bool SubcategoriesEnabled { get; set; } = true;
     public bool BrandsEnabled { get; set; } = true;
     public bool ItemTypesEnabled { get; set; } = true;
+    public bool SellingPricesEnabled { get; set; } = true;
+    public bool SerialNumbersEnabled { get; set; } = true;
+    public bool BatchListsEnabled { get; set; } = true;
+    public bool WarrantyPeriodsEnabled { get; set; } = true;
 
     public DateTime? UpdatedAt { get; set; }
 

Backend/ERPCore/Domain/Notifications/Modules/NotificationModules.cs

@@ -0,0 +1,34 @@
+namespace ERPCore.Domain.Notifications.Modules;
+
+[NotificationModule("sale.create", "Sale Created", "Raised when a sales document is created.", 10)]
+public sealed class SaleCreateNotificationModule;
+
+[NotificationModule("sale.posted", "Sale Posted", "Raised when a sales document is posted.", 20)]
+public sealed class SalePostedNotificationModule;
+
+[NotificationModule("grn.created", "GRN Created", "Raised when a goods receipt note is created.", 30)]
+public sealed class GrnCreatedNotificationModule;
+
+[NotificationModule("grn.confirmed", "GRN Confirmed", "Raised when a goods receipt note is confirmed.", 40)]
+public sealed class GrnConfirmedNotificationModule;
+
+[NotificationModule("purchase.order.created", "Purchase Order Created", "Raised when a purchase order is created.", 50)]
+public sealed class PurchaseOrderCreatedNotificationModule;
+
+[NotificationModule("purchase.order.approved", "Purchase Order Approved", "Raised when a purchase order is approved.", 60)]
+public sealed class PurchaseOrderApprovedNotificationModule;
+
+[NotificationModule("purchase.return.created", "Purchase Return Created", "Raised when a purchase return is created.", 70)]
+public sealed class PurchaseReturnCreatedNotificationModule;
+
+[NotificationModule("stock.adjustment.created", "Stock Adjustment Created", "Raised when a stock adjustment is created.", 80)]
+public sealed class StockAdjustmentCreatedNotificationModule;
+
+[NotificationModule("stock.transfer.created", "Stock Transfer Created", "Raised when a stock transfer is created.", 90)]
+public sealed class StockTransferCreatedNotificationModule;
+
+[NotificationModule("item.created", "Item Created", "Raised when an item master record is created.", 100)]
+public sealed class ItemCreatedNotificationModule;
+
+[NotificationModule("item.updated", "Item Updated", "Raised when an item master record is updated.", 110)]
+public sealed class ItemUpdatedNotificationModule;

Backend/ERPCore/Domain/Notifications/NotificationChannel.cs

@@ -0,0 +1,8 @@
+namespace ERPCore.Domain.Notifications;
+
+public enum NotificationChannel
+{
+    Email,
+    Sms,
+    InApp
+}

Backend/ERPCore/Domain/Notifications/NotificationModuleAttribute.cs

@@ -0,0 +1,18 @@
+namespace ERPCore.Domain.Notifications;
+
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
+public sealed class NotificationModuleAttribute : Attribute
+{
+    public string Key { get; }
+    public string Label { get; }
+    public string Description { get; }
+    public int SortOrder { get; }
+
+    public NotificationModuleAttribute(string key, string label, string description, int sortOrder)
+    {
+        Key = key;
+        Label = label;
+        Description = description;
+        SortOrder = sortOrder;
+    }
+}

Backend/ERPCore/Domain/Notifications/NotificationModuleDefinition.cs

@@ -0,0 +1,7 @@
+namespace ERPCore.Domain.Notifications;
+
+public sealed record NotificationModuleDefinition(
+    string Key,
+    string Label,
+    string Description,
+    int SortOrder);

Backend/ERPCore/Dtos/Config/ProductConfigDtos.cs

@@ -4,10 +4,14 @@ namespace ERPCore.Dtos.Config;
 
 /// <summary>
 /// Product configuration resource (docs/11-BACKEND-PHASE1.md §2.8). Singleton.
-/// <see cref="ItemTypesEnabled"/> is advisory (frontend-honoured) — see the entity docs.
+/// <see cref="ItemTypesEnabled"/> is advisory (frontend-honoured) - see the entity docs.
+/// <see cref="SellingPricesEnabled"/>, <see cref="SerialNumbersEnabled"/>,
+/// <see cref="BatchListsEnabled"/> and <see cref="WarrantyPeriodsEnabled"/> are enforced
+/// when items are written.
 /// </summary>
 public sealed record ProductConfigDto(
     bool SubcategoriesEnabled, bool BrandsEnabled, bool ItemTypesEnabled,
+    bool SellingPricesEnabled, bool SerialNumbersEnabled, bool BatchListsEnabled, bool WarrantyPeriodsEnabled,
     DateTime? UpdatedAt, int? UpdatedBy);
 
 /// <summary>
@@ -15,8 +19,8 @@ public sealed record ProductConfigDto(
 /// <para>
 /// The flags are <see cref="bool"/>? deliberately: <c>[Required]</c> on a non-nullable bool
 /// is a no-op (it always has a value), so a body of <c>{}</c> would bind every flag to
-/// <c>false</c> and silently switch all three features off. Nullable makes the requirement
-/// actually bind — an omitted flag is a 400, not an accidental disable.
+/// <c>false</c> and silently switch everything off. Nullable makes the requirement actually
+/// bind - an omitted flag is a 400, not an accidental disable.
 /// </para>
 /// </summary>
 public sealed class UpdateProductConfigRequest
@@ -24,4 +28,8 @@ public sealed class UpdateProductConfigRequest
     [Required] public bool? SubcategoriesEnabled { get; set; }
     [Required] public bool? BrandsEnabled { get; set; }
     [Required] public bool? ItemTypesEnabled { get; set; }
+    [Required] public bool? SellingPricesEnabled { get; set; }
+    [Required] public bool? SerialNumbersEnabled { get; set; }
+    [Required] public bool? BatchListsEnabled { get; set; }
+    [Required] public bool? WarrantyPeriodsEnabled { get; set; }
 }

Backend/ERPCore/Dtos/Notifications/NotificationConfigDtos.cs

@@ -0,0 +1,29 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace ERPCore.Dtos.Notifications;
+
+public sealed record NotificationModuleConfigDto(
+    string ModuleKey,
+    string Label,
+    string Description,
+    bool EmailEnabled,
+    bool SmsEnabled,
+    bool InAppEnabled);
+
+public sealed record NotificationConfigDto(
+    IReadOnlyList<NotificationModuleConfigDto> Modules,
+    DateTime? UpdatedAt,
+    int? UpdatedBy);
+
+public sealed class UpdateNotificationModuleRequest
+{
+    [Required, StringLength(100)] public string ModuleKey { get; set; } = string.Empty;
+    [Required] public bool? EmailEnabled { get; set; }
+    [Required] public bool? SmsEnabled { get; set; }
+    [Required] public bool? InAppEnabled { get; set; }
+}
+
+public sealed class UpdateNotificationConfigRequest
+{
+    [Required, MinLength(0)] public List<UpdateNotificationModuleRequest> Modules { get; set; } = new();
+}

Backend/ERPCore/Infra/Persistence/Configurations/NotificationConfigConfiguration.cs

@@ -0,0 +1,29 @@
+using ERPCore.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class NotificationConfigConfiguration : IEntityTypeConfiguration<NotificationConfig>
+{
+    public void Configure(EntityTypeBuilder<NotificationConfig> builder)
+    {
+        builder.ToTable("notification_config", t =>
+            t.HasCheckConstraint("ck_notification_config_singleton", $"\"NotificationConfigId\" = {NotificationConfig.SingletonId}"));
+
+        builder.HasKey(c => c.NotificationConfigId);
+        builder.Property(c => c.NotificationConfigId).ValueGeneratedNever();
+
+        builder.Property(c => c.RowVersion).IsRowVersion();
+
+        builder.HasMany(c => c.Modules)
+            .WithOne(m => m.NotificationConfig)
+            .HasForeignKey(m => m.NotificationConfigId)
+            .OnDelete(DeleteBehavior.Cascade);
+
+        builder.HasOne(c => c.UpdatedByUser)
+            .WithMany()
+            .HasForeignKey(c => c.UpdatedBy)
+            .OnDelete(DeleteBehavior.Restrict);
+    }
+}

Backend/ERPCore/Infra/Persistence/Configurations/NotificationConfigModuleConfiguration.cs

@@ -0,0 +1,21 @@
+using ERPCore.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class NotificationConfigModuleConfiguration : IEntityTypeConfiguration<NotificationConfigModule>
+{
+    public void Configure(EntityTypeBuilder<NotificationConfigModule> builder)
+    {
+        builder.ToTable("notification_config_modules");
+        builder.HasKey(m => m.NotificationConfigModuleId);
+
+        builder.Property(m => m.ModuleKey).IsRequired().HasMaxLength(100);
+        builder.HasIndex(m => m.ModuleKey).IsUnique();
+
+        builder.Property(m => m.EmailEnabled).IsRequired().HasDefaultValue(false);
+        builder.Property(m => m.SmsEnabled).IsRequired().HasDefaultValue(false);
+        builder.Property(m => m.InAppEnabled).IsRequired().HasDefaultValue(false);
+    }
+}

Backend/ERPCore/Infra/Persistence/Configurations/ProductConfigConfiguration.cs

@@ -25,6 +25,10 @@ public sealed class ProductConfigConfiguration : IEntityTypeConfiguration<Produc
         builder.Property(c => c.SubcategoriesEnabled).IsRequired().HasDefaultValue(true);
         builder.Property(c => c.BrandsEnabled).IsRequired().HasDefaultValue(true);
         builder.Property(c => c.ItemTypesEnabled).IsRequired().HasDefaultValue(true);
+        builder.Property(c => c.SellingPricesEnabled).IsRequired().HasDefaultValue(true);
+        builder.Property(c => c.SerialNumbersEnabled).IsRequired().HasDefaultValue(true);
+        builder.Property(c => c.BatchListsEnabled).IsRequired().HasDefaultValue(true);
+        builder.Property(c => c.WarrantyPeriodsEnabled).IsRequired().HasDefaultValue(true);
 
         // PostgreSQL xmin system column as the optimistic concurrency token (ETag).
         builder.Property(c => c.RowVersion).IsRowVersion();

Backend/ERPCore/Infra/Persistence/Configurations/SubNavItemConfiguration.cs

@@ -33,6 +33,7 @@ public sealed class SubNavItemConfiguration : IEntityTypeConfiguration<SubNavIte
             new SubNavItem { SubNavItemId = 6, NavItemId = 2, Code = "products.configuration", Label = "Configuration", Href = "/dashboard/products/settings", SortOrder = 6 },
             new SubNavItem { SubNavItemId = 7, NavItemId = 9, Code = "settings.roles", Label = "Roles", Href = "/dashboard/settings/roles", SortOrder = 1 },
             new SubNavItem { SubNavItemId = 8, NavItemId = 9, Code = "settings.users", Label = "Users", Href = "/dashboard/settings/users", SortOrder = 2 },
+            new SubNavItem { SubNavItemId = 24, NavItemId = 9, Code = "settings.notification-config", Label = "Notification Config", Href = "/dashboard/settings/notification-config", SortOrder = 3 },
             new SubNavItem { SubNavItemId = 23, NavItemId = 13, Code = "sales.bundle-sales", Label = "Bundle Sales", Href = "/dashboard/sales/bundles", SortOrder = 1 },
             // Procurement (NavItemId 4) children — mirror the hub page order.
             // IDs 17-20 (not 9-12): 9-12 were already claimed by the Ledgers sub-items below;

Backend/ERPCore/Infra/Persistence/DataSeeder.cs

@@ -43,8 +43,9 @@ public static class DataSeeder
     {
         var dirty = await SeedReasonCodesAsync(db, ct);
         dirty |= await SeedItemTypesAsync(db, ct);
-       // dirty |= await SeedCompanyProfileAsync(db, ct);
+        // dirty |= await SeedCompanyProfileAsync(db, ct);
         dirty |= await SeedProductConfigAsync(db, ct);
+        dirty |= await SeedNotificationConfigAsync(db, ct);
         dirty |= await SeedSalesMastersAsync(db, ct);
         dirty |= await SeedSalesStockAsync(db, ct);
         dirty |= await SeedSalesAsync(db, ct);
@@ -100,7 +101,22 @@ public static class DataSeeder
             ConfigId = ProductConfig.SingletonId,
             SubcategoriesEnabled = true,
             BrandsEnabled = true,
-            ItemTypesEnabled = true
+            ItemTypesEnabled = true,
+            SellingPricesEnabled = true,
+            SerialNumbersEnabled = true,
+            BatchListsEnabled = true,
+            WarrantyPeriodsEnabled = true
+        });
+        return true;
+    }
+
+    private static async Task<bool> SeedNotificationConfigAsync(ErpDbContext db, CancellationToken ct)
+    {
+        if (await db.NotificationConfig.AnyAsync(c => c.NotificationConfigId == NotificationConfig.SingletonId, ct)) return false;
+
+        db.NotificationConfig.Add(new NotificationConfig
+        {
+            NotificationConfigId = NotificationConfig.SingletonId
         });
         return true;
     }

Backend/ERPCore/Infra/Persistence/ErpDbContext.cs

@@ -38,6 +38,9 @@ public class ErpDbContext : DbContext
     
     /// <summary>Singleton row (FR-MD-11).</summary>
     public DbSet<ProductConfig> ProductConfig => Set<ProductConfig>();
+    /// <summary>Singleton row for notification delivery preferences.</summary>
+    public DbSet<NotificationConfig> NotificationConfig => Set<NotificationConfig>();
+    public DbSet<NotificationConfigModule> NotificationConfigModules => Set<NotificationConfigModule>();
 
     // --- Cross-cutting (docs/10 Part C.7) ---
     public DbSet<User> Users => Set<User>();

Backend/ERPCore/Migrations/20260820100345_AddNotificationConfigModulePreferences.cs

@@ -0,0 +1,103 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace ERPCore.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddNotificationConfigModulePreferences : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "notification_config",
+                columns: table => new
+                {
+                    NotificationConfigId = table.Column<int>(type: "integer", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
+                    UpdatedBy = table.Column<int>(type: "integer", nullable: true),
+                    xmin = table.Column<uint>(type: "xid", rowVersion: true, nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_notification_config", x => x.NotificationConfigId);
+                    table.CheckConstraint("ck_notification_config_singleton", "\"NotificationConfigId\" = 1");
+                    table.ForeignKey(
+                        name: "FK_notification_config_users_UpdatedBy",
+                        column: x => x.UpdatedBy,
+                        principalTable: "users",
+                        principalColumn: "UserId",
+                        onDelete: ReferentialAction.Restrict);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "notification_config_modules",
+                columns: table => new
+                {
+                    NotificationConfigModuleId = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    NotificationConfigId = table.Column<int>(type: "integer", nullable: false),
+                    ModuleKey = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: false),
+                    EmailEnabled = table.Column<bool>(type: "boolean", nullable: false, defaultValue: false),
+                    SmsEnabled = table.Column<bool>(type: "boolean", nullable: false, defaultValue: false),
+                    InAppEnabled = table.Column<bool>(type: "boolean", nullable: false, defaultValue: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_notification_config_modules", x => x.NotificationConfigModuleId);
+                    table.ForeignKey(
+                        name: "FK_notification_config_modules_notification_config_Notificatio~",
+                        column: x => x.NotificationConfigId,
+                        principalTable: "notification_config",
+                        principalColumn: "NotificationConfigId",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.Sql("""
+                INSERT INTO sub_nav_items ("SubNavItemId", "NavItemId", "Code", "Href", "Icon", "Label", "SortOrder")
+                VALUES (24, 9, 'settings.notification-config', '/dashboard/settings/notification-config', NULL, 'Notification Config', 3)
+                ON CONFLICT ("SubNavItemId") DO UPDATE
+                SET "NavItemId" = EXCLUDED."NavItemId",
+                    "Code" = EXCLUDED."Code",
+                    "Href" = EXCLUDED."Href",
+                    "Icon" = EXCLUDED."Icon",
+                    "Label" = EXCLUDED."Label",
+                    "SortOrder" = EXCLUDED."SortOrder";
+                """);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_notification_config_UpdatedBy",
+                table: "notification_config",
+                column: "UpdatedBy");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_notification_config_modules_ModuleKey",
+                table: "notification_config_modules",
+                column: "ModuleKey",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_notification_config_modules_NotificationConfigId",
+                table: "notification_config_modules",
+                column: "NotificationConfigId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "notification_config_modules");
+
+            migrationBuilder.DropTable(
+                name: "notification_config");
+
+            migrationBuilder.DeleteData(
+                table: "sub_nav_items",
+                keyColumn: "SubNavItemId",
+                keyValue: 24);
+        }
+    }
+}

Backend/ERPCore/Migrations/20260820125724_AddProductConfigFeatureFlags.cs

@@ -0,0 +1,62 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ERPCore.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddProductConfigFeatureFlags : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<bool>(
+                name: "BatchListsEnabled",
+                table: "product_config",
+                type: "boolean",
+                nullable: false,
+                defaultValue: true);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "SellingPricesEnabled",
+                table: "product_config",
+                type: "boolean",
+                nullable: false,
+                defaultValue: true);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "SerialNumbersEnabled",
+                table: "product_config",
+                type: "boolean",
+                nullable: false,
+                defaultValue: true);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "WarrantyPeriodsEnabled",
+                table: "product_config",
+                type: "boolean",
+                nullable: false,
+                defaultValue: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "BatchListsEnabled",
+                table: "product_config");
+
+            migrationBuilder.DropColumn(
+                name: "SellingPricesEnabled",
+                table: "product_config");
+
+            migrationBuilder.DropColumn(
+                name: "SerialNumbersEnabled",
+                table: "product_config");
+
+            migrationBuilder.DropColumn(
+                name: "WarrantyPeriodsEnabled",
+                table: "product_config");
+        }
+    }
+}

Backend/ERPCore/Migrations/ErpDbContextModelSnapshot.cs

@@ -2354,6 +2354,74 @@ namespace ERPCore.Migrations
                         });
                 });
 
+            modelBuilder.Entity("ERPCore.Domain.Entities.NotificationConfig", b =>
+                {
+                    b.Property<int>("NotificationConfigId")
+                        .HasColumnType("integer");
+
+                    b.Property<uint>("RowVersion")
+                        .IsConcurrencyToken()
+                        .ValueGeneratedOnAddOrUpdate()
+                        .HasColumnType("xid")
+                        .HasColumnName("xmin");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<int?>("UpdatedBy")
+                        .HasColumnType("integer");
+
+                    b.HasKey("NotificationConfigId");
+
+                    b.HasIndex("UpdatedBy");
+
+                    b.ToTable("notification_config", null, t =>
+                        {
+                            t.HasCheckConstraint("ck_notification_config_singleton", "\"NotificationConfigId\" = 1");
+                        });
+                });
+
+            modelBuilder.Entity("ERPCore.Domain.Entities.NotificationConfigModule", b =>
+                {
+                    b.Property<int>("NotificationConfigModuleId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("NotificationConfigModuleId"));
+
+                    b.Property<bool>("EmailEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(false);
+
+                    b.Property<bool>("InAppEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(false);
+
+                    b.Property<string>("ModuleKey")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
+                    b.Property<int>("NotificationConfigId")
+                        .HasColumnType("integer");
+
+                    b.Property<bool>("SmsEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(false);
+
+                    b.HasKey("NotificationConfigModuleId");
+
+                    b.HasIndex("ModuleKey")
+                        .IsUnique();
+
+                    b.HasIndex("NotificationConfigId");
+
+                    b.ToTable("notification_config_modules", (string)null);
+                });
+
             modelBuilder.Entity("ERPCore.Domain.Entities.NumberSequence", b =>
                 {
                     b.Property<int>("SequenceId")
@@ -2973,6 +3041,11 @@ namespace ERPCore.Migrations
                     b.Property<int>("ConfigId")
                         .HasColumnType("integer");
 
+                    b.Property<bool>("BatchListsEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(true);
+
                     b.Property<bool>("BrandsEnabled")
                         .ValueGeneratedOnAdd()
                         .HasColumnType("boolean")
@@ -2989,6 +3062,16 @@ namespace ERPCore.Migrations
                         .HasColumnType("xid")
                         .HasColumnName("xmin");
 
+                    b.Property<bool>("SellingPricesEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(true);
+
+                    b.Property<bool>("SerialNumbersEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(true);
+
                     b.Property<bool>("SubcategoriesEnabled")
                         .ValueGeneratedOnAdd()
                         .HasColumnType("boolean")
@@ -3000,6 +3083,11 @@ namespace ERPCore.Migrations
                     b.Property<int?>("UpdatedBy")
                         .HasColumnType("integer");
 
+                    b.Property<bool>("WarrantyPeriodsEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(true);
+
                     b.HasKey("ConfigId");
 
                     b.HasIndex("UpdatedBy");
@@ -5189,6 +5277,16 @@ namespace ERPCore.Migrations
                             Status = "Active"
                         },
                         new
+                        {
+                            SubNavItemId = 24,
+                            Code = "settings.notification-config",
+                            Href = "/dashboard/settings/notification-config",
+                            Label = "Notification Config",
+                            NavItemId = 9,
+                            SortOrder = 3,
+                            Status = "Active"
+                        },
+                        new
                         {
                             SubNavItemId = 23,
                             Code = "sales.bundle-sales",
@@ -6284,6 +6382,27 @@ namespace ERPCore.Migrations
                     b.Navigation("PayrollRun");
                 });
 
+            modelBuilder.Entity("ERPCore.Domain.Entities.NotificationConfig", b =>
+                {
+                    b.HasOne("ERPCore.Domain.Entities.User", "UpdatedByUser")
+                        .WithMany()
+                        .HasForeignKey("UpdatedBy")
+                        .OnDelete(DeleteBehavior.Restrict);
+
+                    b.Navigation("UpdatedByUser");
+                });
+
+            modelBuilder.Entity("ERPCore.Domain.Entities.NotificationConfigModule", b =>
+                {
+                    b.HasOne("ERPCore.Domain.Entities.NotificationConfig", "NotificationConfig")
+                        .WithMany("Modules")
+                        .HasForeignKey("NotificationConfigId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("NotificationConfig");
+                });
+
             modelBuilder.Entity("ERPCore.Domain.Entities.PayrollLine", b =>
                 {
                     b.HasOne("ERPCore.Domain.Entities.Employee", "Employee")
@@ -7416,6 +7535,11 @@ namespace ERPCore.Migrations
                     b.Navigation("Children");
                 });
 
+            modelBuilder.Entity("ERPCore.Domain.Entities.NotificationConfig", b =>
+                {
+                    b.Navigation("Modules");
+                });
+
             modelBuilder.Entity("ERPCore.Domain.Entities.PayrollLine", b =>
                 {
                     b.Navigation("Components");

Backend/ERPCore/Program.cs

@@ -85,6 +85,8 @@ builder.Services.AddScoped<IBrandService, BrandService>();
 builder.Services.AddScoped<IItemTypeService, ItemTypeService>();
 //builder.Services.AddScoped<ICompanyProfileService, CompanyProfileService>();
 builder.Services.AddScoped<IProductConfigService, ProductConfigService>();
+builder.Services.AddSingleton<INotificationModuleCatalog, NotificationModuleCatalog>();
+builder.Services.AddScoped<INotificationConfigService, NotificationConfigService>();
 builder.Services.AddScoped<IVendorService, VendorService>();
 builder.Services.AddScoped<IWarehouseService, WarehouseService>();
 

Backend/ERPCore/Services/Interfaces/INotificationConfigService.cs

@@ -0,0 +1,12 @@
+using ERPCore.Common.Http;
+using ERPCore.Domain.Notifications;
+using ERPCore.Dtos.Notifications;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface INotificationConfigService
+{
+    Task<ETagged<NotificationConfigDto>> GetAsync(CancellationToken ct = default);
+    Task<ETagged<NotificationConfigDto>> UpdateAsync(UpdateNotificationConfigRequest request, uint expectedRowVersion, CancellationToken ct = default);
+    Task<IReadOnlyList<NotificationChannel>> ResolveEnabledChannelsAsync(string moduleKey, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/INotificationModuleCatalog.cs

@@ -0,0 +1,9 @@
+using ERPCore.Domain.Notifications;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface INotificationModuleCatalog
+{
+    IReadOnlyList<NotificationModuleDefinition> GetAll();
+    NotificationModuleDefinition? Find(string moduleKey);
+}

Backend/ERPCore/Services/ItemService.cs

@@ -1,6 +1,7 @@
 using ERPCore.Common.Http;
 using ERPCore.Domain.Entities;
 using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Config;
 using ERPCore.Dtos.Common;
 using ERPCore.Dtos.Items;
 using ERPCore.Infra.UoW;
@@ -108,9 +109,11 @@ public sealed class ItemService : IItemService
         if (await _items.Query().AnyAsync(i => i.Sku == request.Sku, ct))
             throw new DomainException(ErrorCodes.SkuDuplicate, $"An item with SKU '{request.Sku}' already exists.", 400);
 
+        var config = (await _config.GetAsync(ct)).Value;
         await ValidateReferencesAsync(
             request.CategoryId, request.SubCategoryId, request.BrandId,
-            request.BaseUomId, request.DefaultVendorId, ct);
+            request.BaseUomId, request.DefaultVendorId, config, ct);
+        ValidateFeatureConfiguration(request, config);
 
         ItemContent.ValidatePair(request.ContentQty, request.ContentUnit);
         var (contentBaseQty, contentBaseUnit) = ItemContent.Normalize(request.ContentQty, request.ContentUnit);
@@ -163,9 +166,11 @@ public sealed class ItemService : IItemService
             && await _items.Query().AnyAsync(i => i.Sku == request.Sku && i.ItemId != itemId, ct))
             throw new DomainException(ErrorCodes.SkuDuplicate, $"An item with SKU '{request.Sku}' already exists.", 400);
 
+        var config = (await _config.GetAsync(ct)).Value;
         await ValidateReferencesAsync(
             request.CategoryId, request.SubCategoryId, request.BrandId,
-            request.BaseUomId, request.DefaultVendorId, ct);
+            request.BaseUomId, request.DefaultVendorId, config, ct);
+        ValidateFeatureConfiguration(request, config);
 
         // The base UOM is the sole meaning of every quantity recorded against this item —
         // stock layers, ledger rows and document lines are all plain counts of it. Once any
@@ -280,10 +285,9 @@ public sealed class ItemService : IItemService
     /// it is advisory and honoured by the frontend only (docs/11 §2.8).
     /// </summary>
     private async Task ValidateReferencesAsync(
-        int categoryId, int? subCategoryId, int? brandId, int baseUomId, int? defaultVendorId, CancellationToken ct)
+        int categoryId, int? subCategoryId, int? brandId, int baseUomId, int? defaultVendorId,
+        ProductConfigDto config, CancellationToken ct)
     {
-        var config = (await _config.GetAsync(ct)).Value;
-
         if (!await _categories.Query().AnyAsync(c => c.CategoryId == categoryId, ct))
             throw new DomainException(ErrorCodes.Validation, $"Category {categoryId} does not exist.", 422);
 
@@ -337,6 +341,46 @@ public sealed class ItemService : IItemService
         }
     }
 
+    private static void ValidateFeatureConfiguration(CreateItemRequest request, ProductConfigDto config)
+        => ValidateFeatureConfiguration(
+            request.SellingMinPrice, request.SellingMaxPrice, request.SellingFlatPrice,
+            request.TrackingMode, request.Warranty, config);
+
+    private static void ValidateFeatureConfiguration(UpdateItemRequest request, ProductConfigDto config)
+        => ValidateFeatureConfiguration(
+            request.SellingMinPrice, request.SellingMaxPrice, request.SellingFlatPrice,
+            request.TrackingMode, request.Warranty, config);
+
+    private static void ValidateFeatureConfiguration(
+        decimal? sellingMinPrice, decimal? sellingMaxPrice, decimal? sellingFlatPrice,
+        TrackingMode trackingMode, Warranty warranty, ProductConfigDto config)
+    {
+        if (!config.SellingPricesEnabled &&
+            (sellingMinPrice is not null || sellingMaxPrice is not null || sellingFlatPrice is not null))
+            throw new DomainException(
+                ErrorCodes.ConfigDisabled,
+                "Selling prices are disabled in the product configuration; sellingMinPrice, sellingMaxPrice and sellingFlatPrice must be null.",
+                422);
+
+        if (!config.SerialNumbersEnabled && trackingMode == TrackingMode.Serial)
+            throw new DomainException(
+                ErrorCodes.ConfigDisabled,
+                "Serial numbers are disabled in the product configuration; trackingMode cannot be Serial.",
+                422);
+
+        if (!config.BatchListsEnabled && trackingMode == TrackingMode.Batch)
+            throw new DomainException(
+                ErrorCodes.ConfigDisabled,
+                "Batch lists are disabled in the product configuration; trackingMode cannot be Batch.",
+                422);
+
+        if (!config.WarrantyPeriodsEnabled && warranty == Warranty.Warranty)
+            throw new DomainException(
+                ErrorCodes.ConfigDisabled,
+                "Warranty periods are disabled in the product configuration; warranty cannot be Warranty.",
+                422);
+    }
+
     /// <summary>
     /// A warranty-tracked item must declare a coverage period (one of
     /// <see cref="WarrantyPeriods.AllowedMonths"/>); a non-warranty item carries none —

Backend/ERPCore/Services/NotificationConfigService.cs

@@ -0,0 +1,143 @@
+using ERPCore.Common.Http;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Notifications;
+using ERPCore.Dtos.Notifications;
+using ERPCore.Infra.Auth;
+using ERPCore.Infra.UoW;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class NotificationConfigService : INotificationConfigService
+{
+    private readonly IRepository<NotificationConfig> _config;
+    private readonly IRepository<NotificationConfigModule> _modules;
+    private readonly INotificationModuleCatalog _catalog;
+    private readonly ICurrentUser _currentUser;
+    private readonly IUnitOfWork _uow;
+
+    public NotificationConfigService(
+        IRepository<NotificationConfig> config,
+        IRepository<NotificationConfigModule> modules,
+        INotificationModuleCatalog catalog,
+        ICurrentUser currentUser,
+        IUnitOfWork uow)
+    {
+        _config = config;
+        _modules = modules;
+        _catalog = catalog;
+        _currentUser = currentUser;
+        _uow = uow;
+    }
+
+    public async Task<ETagged<NotificationConfigDto>> GetAsync(CancellationToken ct = default)
+    {
+        var config = await _config.Query().AsNoTracking()
+            .Include(c => c.Modules)
+            .FirstOrDefaultAsync(c => c.NotificationConfigId == NotificationConfig.SingletonId, ct)
+            ?? throw new NotFoundException("Notification configuration has not been seeded.");
+
+        return new ETagged<NotificationConfigDto>(Map(config), config.RowVersion);
+    }
+
+    public async Task<ETagged<NotificationConfigDto>> UpdateAsync(UpdateNotificationConfigRequest request, uint expectedRowVersion, CancellationToken ct = default)
+    {
+        var config = await _config.Query()
+            .Include(c => c.Modules)
+            .FirstOrDefaultAsync(c => c.NotificationConfigId == NotificationConfig.SingletonId, ct)
+            ?? throw new NotFoundException("Notification configuration has not been seeded.");
+
+        if (config.RowVersion != expectedRowVersion)
+            throw new DomainException(ErrorCodes.ConcurrencyConflict, "The notification configuration was modified by another request.", 412);
+
+        var catalog = _catalog.GetAll();
+        var inputs = request.Modules ?? new List<UpdateNotificationModuleRequest>();
+        if (inputs.Any(x => string.IsNullOrWhiteSpace(x.ModuleKey)))
+            throw new DomainException(ErrorCodes.Validation, "Notification module keys cannot be empty.", 400);
+        if (inputs.Select(x => x.ModuleKey.Trim()).Distinct(StringComparer.OrdinalIgnoreCase).Count() != inputs.Count)
+            throw new DomainException(ErrorCodes.Validation, "Duplicate notification module keys are not allowed.", 400);
+
+        var byKey = inputs.ToDictionary(x => x.ModuleKey.Trim(), StringComparer.OrdinalIgnoreCase);
+        var unknown = byKey.Keys.Where(k => catalog.All(m => !string.Equals(m.Key, k, StringComparison.OrdinalIgnoreCase))).ToList();
+        if (unknown.Count > 0)
+            throw new DomainException(ErrorCodes.Validation, $"Unknown notification module key(s): {string.Join(", ", unknown)}.", 422);
+
+        var missing = catalog.Where(m => !byKey.ContainsKey(m.Key)).Select(m => m.Key).ToList();
+        if (missing.Count > 0)
+            throw new DomainException(ErrorCodes.Validation, $"Missing notification module settings for: {string.Join(", ", missing)}.", 422);
+
+        config.Modules.Clear();
+        foreach (var module in catalog)
+        {
+            var input = byKey[module.Key];
+            config.Modules.Add(new NotificationConfigModule
+            {
+                NotificationConfigId = config.NotificationConfigId,
+                ModuleKey = module.Key,
+                EmailEnabled = input.EmailEnabled!.Value,
+                SmsEnabled = input.SmsEnabled!.Value,
+                InAppEnabled = input.InAppEnabled!.Value
+            });
+        }
+
+        config.UpdatedAt = DateTime.UtcNow;
+        config.UpdatedBy = _currentUser.AuditUserId;
+
+        await SaveGuardingConcurrencyAsync(ct);
+        return new ETagged<NotificationConfigDto>(Map(config), config.RowVersion);
+    }
+
+    public async Task<IReadOnlyList<NotificationChannel>> ResolveEnabledChannelsAsync(string moduleKey, CancellationToken ct = default)
+    {
+        var key = moduleKey?.Trim();
+        if (string.IsNullOrWhiteSpace(key)) return Array.Empty<NotificationChannel>();
+
+        var row = await _modules.Query().AsNoTracking()
+            .FirstOrDefaultAsync(m => m.ModuleKey == key, ct);
+
+        if (row is null) return Array.Empty<NotificationChannel>();
+
+        var channels = new List<NotificationChannel>(3);
+        if (row.EmailEnabled) channels.Add(NotificationChannel.Email);
+        if (row.SmsEnabled) channels.Add(NotificationChannel.Sms);
+        if (row.InAppEnabled) channels.Add(NotificationChannel.InApp);
+        return channels;
+    }
+
+    private async Task SaveGuardingConcurrencyAsync(CancellationToken ct)
+    {
+        try
+        {
+            await _uow.SaveChangesAsync(ct);
+        }
+        catch (DbUpdateConcurrencyException)
+        {
+            throw new DomainException(ErrorCodes.ConcurrencyConflict, "The notification configuration was modified by another request.", 412);
+        }
+    }
+
+    private NotificationConfigDto Map(NotificationConfig config)
+    {
+        var rows = config.Modules
+            .ToDictionary(m => m.ModuleKey, m => m, StringComparer.OrdinalIgnoreCase);
+
+        var modules = _catalog.GetAll()
+            .Select(m =>
+            {
+                rows.TryGetValue(m.Key, out var row);
+                return new NotificationModuleConfigDto(
+                    m.Key,
+                    m.Label,
+                    m.Description,
+                    row?.EmailEnabled ?? false,
+                    row?.SmsEnabled ?? false,
+                    row?.InAppEnabled ?? false);
+            })
+            .ToList();
+
+        return new NotificationConfigDto(modules, config.UpdatedAt, config.UpdatedBy);
+    }
+}

Backend/ERPCore/Services/NotificationModuleCatalog.cs

@@ -0,0 +1,35 @@
+using System.Reflection;
+using ERPCore.Domain.Notifications;
+using ERPCore.Domain.Notifications.Modules;
+using ERPCore.Services.Interfaces;
+
+namespace ERPCore.Services;
+
+public sealed class NotificationModuleCatalog : INotificationModuleCatalog
+{
+    private readonly IReadOnlyList<NotificationModuleDefinition> _modules;
+
+    public NotificationModuleCatalog()
+    {
+        var moduleType = typeof(SaleCreateNotificationModule).Assembly;
+        _modules = moduleType.GetTypes()
+            .Select(t => new { Type = t, Attr = t.GetCustomAttribute<NotificationModuleAttribute>() })
+            .Where(x => x.Attr is not null)
+            .Select(x => new NotificationModuleDefinition(x.Attr!.Key, x.Attr.Label, x.Attr.Description, x.Attr.SortOrder))
+            .OrderBy(x => x.SortOrder)
+            .ThenBy(x => x.Key, StringComparer.Ordinal)
+            .ToList();
+
+        var duplicates = _modules.GroupBy(m => m.Key, StringComparer.OrdinalIgnoreCase)
+            .Where(g => g.Count() > 1)
+            .Select(g => g.Key)
+            .ToList();
+        if (duplicates.Count > 0)
+            throw new InvalidOperationException($"Duplicate notification module key(s) found: {string.Join(", ", duplicates)}.");
+    }
+
+    public IReadOnlyList<NotificationModuleDefinition> GetAll() => _modules;
+
+    public NotificationModuleDefinition? Find(string moduleKey)
+        => _modules.FirstOrDefault(m => string.Equals(m.Key, moduleKey, StringComparison.OrdinalIgnoreCase));
+}

Backend/ERPCore/Services/ProductConfigService.cs

@@ -12,7 +12,7 @@ namespace ERPCore.Services;
 
 /// <summary>
 /// Product configuration service (FR-MD-11) over the singleton row seeded by DataSeeder.
-/// Reads are never gated — only writes consult the flags — so switching a feature off
+/// Reads are never gated - only writes consult the flags - so switching a feature off
 /// leaves existing data readable (docs/11-BACKEND-PHASE1.md §2.8).
 /// </summary>
 public sealed class ProductConfigService : IProductConfigService
@@ -46,11 +46,15 @@ public sealed class ProductConfigService : IProductConfigService
         if (config.RowVersion != expectedRowVersion)
             throw new DomainException(ErrorCodes.ConcurrencyConflict, "The configuration was modified by another request.", 412);
 
-        // Non-null by [Required] on the nullable bools — an omitted flag is a 400, so the
+        // Non-null by [Required] on the nullable bools - an omitted flag is a 400, so the
         // model binder has already rejected anything that would reach here with a null.
         config.SubcategoriesEnabled = request.SubcategoriesEnabled!.Value;
         config.BrandsEnabled = request.BrandsEnabled!.Value;
         config.ItemTypesEnabled = request.ItemTypesEnabled!.Value;
+        config.SellingPricesEnabled = request.SellingPricesEnabled!.Value;
+        config.SerialNumbersEnabled = request.SerialNumbersEnabled!.Value;
+        config.BatchListsEnabled = request.BatchListsEnabled!.Value;
+        config.WarrantyPeriodsEnabled = request.WarrantyPeriodsEnabled!.Value;
         config.UpdatedAt = DateTime.UtcNow;
         config.UpdatedBy = _currentUser.AuditUserId;
 
@@ -67,5 +71,7 @@ public sealed class ProductConfigService : IProductConfigService
     }
 
     private static ProductConfigDto Map(ProductConfig c) => new(
-        c.SubcategoriesEnabled, c.BrandsEnabled, c.ItemTypesEnabled, c.UpdatedAt, c.UpdatedBy);
+        c.SubcategoriesEnabled, c.BrandsEnabled, c.ItemTypesEnabled,
+        c.SellingPricesEnabled, c.SerialNumbersEnabled, c.BatchListsEnabled, c.WarrantyPeriodsEnabled,
+        c.UpdatedAt, c.UpdatedBy);
 }