product and sales fixers

Backend/ERPCore/Domain/Entities/ItemImage.cs

@@ -0,0 +1,27 @@
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// A product photo attached to an item. Like <see cref="EmployeeDocument"/>, the file lives
+/// behind <see cref="Infra.Storage.IFileStorageService"/> under a server-generated name and is
+/// only reachable through the authenticated items API — never a static path. Only uploadable
+/// while <see cref="ProductConfig.ItemImagesEnabled"/> is on; existing images stay readable
+/// after the flag is switched off (reads are never gated).
+/// </summary>
+public class ItemImage
+{
+    public int ItemImageId { get; set; }
+    public int ItemId { get; set; }
+    public Item? Item { get; set; }
+
+    public string OriginalFileName { get; set; } = string.Empty;
+    public string StoredFileName { get; set; } = string.Empty;
+    public string RelativePath { get; set; } = string.Empty;
+    public string ContentType { get; set; } = string.Empty;
+    public long SizeBytes { get; set; }
+
+    /// <summary>Display order; the lowest is the item's main image.</summary>
+    public int SortOrder { get; set; }
+
+    public int UploadedBy { get; set; }
+    public DateTime UploadedAt { get; set; }
+}

Backend/ERPCore/Domain/Entities/ProductConfig.cs

@@ -31,6 +31,26 @@ public class ProductConfig
     public bool BatchListsEnabled { get; set; } = true;
     public bool WarrantyPeriodsEnabled { get; set; } = true;
 
+    /// <summary>
+    /// Lets the item create screen add a new item variant (item type) on the spot, instead
+    /// of only picking from the Item Variants master. Advisory like <see cref="ItemTypesEnabled"/>
+    /// - it gates a UI shortcut; the Item Variants master itself stays available either way.
+    /// </summary>
+    public bool CustomVariantsEnabled { get; set; }
+
+    /// <summary>
+    /// Allows photos to be uploaded to items (<see cref="ItemImage"/>). Enforced on upload
+    /// (<c>CONFIG_DISABLED</c>); images added earlier stay viewable when switched off.
+    /// </summary>
+    public bool ItemImagesEnabled { get; set; }
+
+    /// <summary>
+    /// Lets items use the active <see cref="WarrantyPeriod"/> master rows alongside the default
+    /// <see cref="Enums.WarrantyPeriods.AllowedMonths"/>. Enforced on item writes. The periods
+    /// themselves are managed under Products, not here.
+    /// </summary>
+    public bool CustomWarrantyPeriodsEnabled { get; set; }
+
     public DateTime? UpdatedAt { get; set; }
 
     public int? UpdatedBy { get; set; }

Backend/ERPCore/Domain/Entities/SalesConfig.cs

@@ -0,0 +1,61 @@
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// Sales configuration — a singleton row (single-tenant, docs/00-CORE §1), same shape as
+/// <see cref="BranchConfig"/>. When <see cref="AllowCashCustomer"/> is on, sales documents may
+/// be raised against the generic "Cash Customer" (<see cref="CashCustomerId"/>) and the New Sale
+/// form defaults to it; when off, a real customer must be picked and the cash customer is
+/// rejected server-side (see SalesDomainService.ValidateSalesHeaderAsync).
+/// </summary>
+public class SalesConfig
+{
+    /// <summary>Always 1 - the singleton row's id.</summary>
+    public const int SingletonId = 1;
+
+    public int ConfigId { get; set; }
+
+    public bool AllowCashCustomer { get; set; }
+
+    /// <summary>The Customer row used for cash (walk-in, unnamed) sales. Created on first
+    /// enabling <see cref="AllowCashCustomer"/> and kept afterwards, so switching the option
+    /// off and on again reuses the same customer (and its sales history).</summary>
+    public int? CashCustomerId { get; set; }
+    public Customer? CashCustomer { get; set; }
+
+    /// <summary>When on, sales invoice lines may carry a free quantity (the New Sale "Free"
+    /// column); when off, the column is hidden and a free qty above zero is rejected server-side
+    /// (see SalesInvoiceService.BuildLinesAsync). Defaults on, matching the behaviour before
+    /// this option existed.</summary>
+    public bool AllowFreeItems { get; set; } = true;
+
+    /// <summary>When on, sales invoice lines may carry a line discount (the New Sale "Disc %"
+    /// column); when off, the column is hidden and a discount above zero is rejected server-side
+    /// (see SalesInvoiceService.BuildLinesAsync). Defaults on, matching the behaviour before
+    /// this option existed.</summary>
+    public bool AllowDiscounts { get; set; } = true;
+
+    /// <summary>When on, posting a sale (invoice, slip, bundle) may issue more than the stock on
+    /// hand — the shortfall drives on-hand negative (see FifoCostingService.ConsumeAsync) and the
+    /// pre-post check reports it as a warning only. When off (default), posting is blocked with
+    /// STOCK_NEGATIVE_BLOCKED until stock covers every line.</summary>
+    public bool AllowOverStockSale { get; set; }
+
+    /// <summary>When on (default) and no <see cref="DefaultWarehouseId"/> is saved, New Sale shows
+    /// a Warehouse picker. When off, a default must be saved.</summary>
+    public bool AllowWarehouseSelection { get; set; } = true;
+
+    /// <summary>Default sales warehouse. Whenever set, New Sale shows only this warehouse (locked)
+    /// and every sales invoice (header and lines) is forced onto it server-side (see
+    /// SalesDomainService.GetForcedSalesWarehouseIdAsync). Required while
+    /// <see cref="AllowWarehouseSelection"/> is off; clearing it brings the picker back.</summary>
+    public int? DefaultWarehouseId { get; set; }
+    public Warehouse? DefaultWarehouse { get; set; }
+
+    public DateTime? UpdatedAt { get; set; }
+
+    public int? UpdatedBy { get; set; }
+    public User? UpdatedByUser { get; set; }
+
+    /// <summary>PostgreSQL xmin-backed optimistic concurrency token (ETag source).</summary>
+    public uint RowVersion { get; set; }
+}

Backend/ERPCore/Domain/Entities/User.cs

@@ -15,6 +15,12 @@ public class User
     /// <summary>Seeded fallback actor for unauthenticated/system operations.</summary>
     public const int SystemUserId = 1;
 
+    /// <summary>
+    /// Username prefix of a permanently deleted login whose row is kept only because history
+    /// (audit log, documents) still references it. Such rows are hidden from user management.
+    /// </summary>
+    public const string DeletedUsernamePrefix = "deleted-user-";
+
     public int UserId { get; set; }
     public string Username { get; set; } = string.Empty;
     public string DisplayName { get; set; } = string.Empty;

Backend/ERPCore/Domain/Entities/WarrantyPeriod.cs

@@ -0,0 +1,23 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// Custom warranty period master — a coverage length offered to items alongside the fixed
+/// defaults in <see cref="WarrantyPeriods.AllowedMonths"/>, while
+/// <see cref="ProductConfig.CustomWarrantyPeriodsEnabled"/> is on.
+/// <para>
+/// Always in months (a "2 year" entry is stored as 24). Like <see cref="ItemType"/> it is
+/// deliberately unlinked: an item stores the number of months itself, not a reference, so
+/// deactivating a period only stops it being offered — items already using it keep it.
+/// The length is immutable (no PUT); a different length is a different row.
+/// </para>
+/// </summary>
+public class WarrantyPeriod
+{
+    public int WarrantyPeriodId { get; set; }
+    public int Months { get; set; }
+    public EntityStatus Status { get; set; } = EntityStatus.Active;
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+}