Backend/ERPCore/Domain/Entities/Grn.cs

@@ -22,6 +22,11 @@ public class Grn
     public int WarehouseId { get; set; }
     public Warehouse? Warehouse { get; set; }
 
+    /// <summary>Owning branch, set explicitly at creation — warehouses are shared across
+    /// branches, so branch scope can no longer be derived from <see cref="Warehouse"/>.</summary>
+    public int BranchId { get; set; }
+    public Branch? Branch { get; set; }
+
     public GrnStatus Status { get; set; } = GrnStatus.Draft;
 
     public int CreatedBy { get; set; }

Backend/ERPCore/Domain/Entities/SalesInvoice.cs

@@ -17,6 +17,11 @@ public class SalesInvoice
     public int WarehouseId { get; set; }
     public Warehouse? Warehouse { get; set; }
 
+    /// <summary>Owning branch, set explicitly at creation — warehouses are shared across
+    /// branches, so branch scope can no longer be derived from <see cref="Warehouse"/>.</summary>
+    public int BranchId { get; set; }
+    public Branch? Branch { get; set; }
+
     public SalesInvoiceType InvoiceType { get; set; } = SalesInvoiceType.B2C;
     public SalesInvoiceStatus Status { get; set; } = SalesInvoiceStatus.Draft;
 

Backend/ERPCore/Domain/Entities/StockAdjustment.cs

@@ -19,6 +19,11 @@ public class StockAdjustment
     public int ReasonCodeId { get; set; }
     public ReasonCode? ReasonCode { get; set; }
 
+    /// <summary>Owning branch, set explicitly at creation — warehouses are shared across
+    /// branches, so branch scope can no longer be derived from <see cref="Warehouse"/>.</summary>
+    public int BranchId { get; set; }
+    public Branch? Branch { get; set; }
+
     public AdjustmentStatus Status { get; set; } = AdjustmentStatus.Posted;
 
     public int CreatedBy { get; set; }

Backend/ERPCore/Domain/Entities/StockCount.cs

@@ -16,6 +16,11 @@ public class StockCount
     public int WarehouseId { get; set; }
     public Warehouse? Warehouse { get; set; }
 
+    /// <summary>Owning branch, set explicitly at creation — warehouses are shared across
+    /// branches, so branch scope can no longer be derived from <see cref="Warehouse"/>.</summary>
+    public int BranchId { get; set; }
+    public Branch? Branch { get; set; }
+
     public CountType CountType { get; set; }
     public CountStatus Status { get; set; } = CountStatus.Draft;
 

Backend/ERPCore/Domain/Entities/StockTransfer.cs

@@ -19,6 +19,11 @@ public class StockTransfer
     public int DestWarehouseId { get; set; }
     public Warehouse? DestWarehouse { get; set; }
 
+    /// <summary>Owning branch, set explicitly at creation — warehouses are shared across
+    /// branches, so branch scope can no longer be derived from src/dest warehouse.</summary>
+    public int BranchId { get; set; }
+    public Branch? Branch { get; set; }
+
     public TransferStatus Status { get; set; } = TransferStatus.Draft;
 
     public int CreatedBy { get; set; }

Backend/ERPCore/Dtos/Grn/GrnDtos.cs

@@ -15,13 +15,13 @@ public sealed record GrnLineDto(
     HoldStatus HoldStatus, int? BatchId, IReadOnlyList<GrnLineWarrantyNumberDto> WarrantyNumbers);
 
 public sealed record GrnDto(
-    int GrnId, string DocNo, int? PoId, int VendorId, int WarehouseId, GrnStatus Status,
+    int GrnId, string DocNo, int? PoId, int VendorId, int WarehouseId, int BranchId, GrnStatus Status,
     int CreatedBy, DateTime CreatedAt, DateTime? PostedAt, string? GlJournalNo,
     int? PurchaseInvoiceId, string? PurchaseInvoiceNo, IReadOnlyList<GrnLineDto> Lines);
 
 /// <summary>Row shape for <c>GET /grns</c> — line count instead of the lines themselves.</summary>
 public sealed record GrnSummaryDto(
-    int GrnId, string DocNo, int? PoId, int VendorId, int WarehouseId, GrnStatus Status,
+    int GrnId, string DocNo, int? PoId, int VendorId, int WarehouseId, int BranchId, GrnStatus Status,
     int CreatedBy, DateTime CreatedAt, DateTime? PostedAt, int LineCount,
     int? PurchaseInvoiceId, string? PurchaseInvoiceNo);
 
@@ -81,6 +81,9 @@ public sealed class CreateGrnRequest
     /// <summary>Required for a direct receipt (no PO); ignored otherwise (vendor derives from the PO).</summary>
     public int? VendorId { get; set; }
     [Required] public int WarehouseId { get; set; }
+    /// <summary>Owning branch for this GRN — warehouses are shared, so this is what actually
+    /// scopes the document (resolved via IBranchConfigService; required when branching is enabled).</summary>
+    [Required] public int BranchId { get; set; }
     [Required, MinLength(1)] public List<CreateGrnLineInput> Lines { get; set; } = new();
 }
 

Backend/ERPCore/Dtos/Sales/SalesInvoiceDtos.cs

@@ -15,14 +15,14 @@ public sealed record SalesInvoiceTotalsDto(
 
 public sealed record SalesInvoiceDto(
     int SalesInvoiceId, string InvoiceNo, DateTime InvoiceDate, int CustomerId,
-    string CustomerSnapshotName, string? CustomerSnapshotTaxNo, int WarehouseId,
+    string CustomerSnapshotName, string? CustomerSnapshotTaxNo, int WarehouseId, int BranchId,
     SalesInvoiceType InvoiceType, SalesInvoiceStatus Status, int CreatedBy, DateTime CreatedAt,
     DateTime? UpdatedAt, string? GlJournalNo, DateTime? GlPostedAt,
     SalesInvoiceTotalsDto Totals, IReadOnlyList<SalesInvoiceLineDto> Lines);
 
 public sealed record SalesInvoiceSummaryDto(
     int SalesInvoiceId, string InvoiceNo, DateTime InvoiceDate, int CustomerId,
-    string CustomerSnapshotName, int WarehouseId, SalesInvoiceType InvoiceType,
+    string CustomerSnapshotName, int WarehouseId, int BranchId, SalesInvoiceType InvoiceType,
     SalesInvoiceStatus Status, SalesInvoiceTotalsDto Totals, DateTime CreatedAt, string? GlJournalNo);
 
 public sealed record SalesInvoicePaymentDto(
@@ -65,6 +65,9 @@ public sealed class CreateSalesInvoiceRequest
 {
     [Required] public int CustomerId { get; set; }
     [Required] public int WarehouseId { get; set; }
+    /// <summary>Owning branch — warehouses are shared, so this is what actually scopes the
+    /// document (resolved via IBranchConfigService).</summary>
+    [Required] public int BranchId { get; set; }
     [Required, EnumDataType(typeof(SalesInvoiceType))] public SalesInvoiceType InvoiceType { get; set; } = SalesInvoiceType.B2C;
     [Required, MinLength(1)] public List<CreateSalesInvoiceLineRequest> Lines { get; set; } = new();
 }
@@ -73,6 +76,9 @@ public sealed class UpdateSalesInvoiceRequest
 {
     [Required] public int CustomerId { get; set; }
     [Required] public int WarehouseId { get; set; }
+    /// <summary>Owning branch — warehouses are shared, so this is what actually scopes the
+    /// document (resolved via IBranchConfigService).</summary>
+    [Required] public int BranchId { get; set; }
     [Required, EnumDataType(typeof(SalesInvoiceType))] public SalesInvoiceType InvoiceType { get; set; } = SalesInvoiceType.B2C;
     [Required, MinLength(1)] public List<CreateSalesInvoiceLineRequest> Lines { get; set; } = new();
 }

Backend/ERPCore/Dtos/Stock/AdjustmentDtos.cs

@@ -8,13 +8,13 @@ namespace ERPCore.Dtos.Stock;
 public sealed record AdjustmentLineDto(int AdjLineId, int ItemId, int? BinId, int? BatchId, decimal QtyDelta);
 
 public sealed record AdjustmentDto(
-    int AdjustmentId, string DocNo, int WarehouseId, int ReasonCodeId, AdjustmentStatus Status,
+    int AdjustmentId, string DocNo, int WarehouseId, int BranchId, int ReasonCodeId, AdjustmentStatus Status,
     int CreatedBy, DateTime CreatedAt, string? GlJournalNo, DateTime? GlPostedAt,
     IReadOnlyList<AdjustmentLineDto> Lines, IReadOnlyList<int> LedgerRefs);
 
 /// <summary>Row shape for <c>GET /stock-adjustments</c> — no lines/ledgerRefs (those need a per-row query).</summary>
 public sealed record AdjustmentSummaryDto(
-    int AdjustmentId, string DocNo, int WarehouseId, int ReasonCodeId, AdjustmentStatus Status,
+    int AdjustmentId, string DocNo, int WarehouseId, int BranchId, int ReasonCodeId, AdjustmentStatus Status,
     int CreatedBy, DateTime CreatedAt, int LineCount, string? GlJournalNo);
 
 // Requests ----------------------------------------------------------------------
@@ -31,6 +31,9 @@ public sealed class CreateAdjustmentLineInput
 public sealed class CreateAdjustmentRequest
 {
     [Required] public int WarehouseId { get; set; }
+    /// <summary>Owning branch — warehouses are shared, so this is what actually scopes the
+    /// document (resolved via IBranchConfigService).</summary>
+    [Required] public int BranchId { get; set; }
     /// <summary>Nullable so an omitted value is a distinct <c>REASON_CODE_REQUIRED</c> error, not 0.</summary>
     public int? ReasonCodeId { get; set; }
     [Required, MinLength(1)] public List<CreateAdjustmentLineInput> Lines { get; set; } = new();

Backend/ERPCore/Dtos/Stock/CountDtos.cs

@@ -8,12 +8,12 @@ namespace ERPCore.Dtos.Stock;
 public sealed record CountLineDto(int CountLineId, int ItemId, int? BinId, decimal SystemQty, decimal? CountedQty, decimal? Variance);
 
 public sealed record CountDto(
-    int CountId, string DocNo, int WarehouseId, CountType CountType, CountStatus Status,
+    int CountId, string DocNo, int WarehouseId, int BranchId, CountType CountType, CountStatus Status,
     int CreatedBy, DateTime CreatedAt, IReadOnlyList<CountLineDto> Lines);
 
 /// <summary>Row shape for <c>GET /stock-counts</c> — line count instead of the lines themselves.</summary>
 public sealed record CountSummaryDto(
-    int CountId, string DocNo, int WarehouseId, CountType CountType, CountStatus Status,
+    int CountId, string DocNo, int WarehouseId, int BranchId, CountType CountType, CountStatus Status,
     int CreatedBy, DateTime CreatedAt, int LineCount);
 
 public sealed record CountPostResultDto(int CountId, CountStatus Status, int? AdjustmentId, string? GlJournalNo, IReadOnlyList<int> LedgerRefs);
@@ -23,6 +23,9 @@ public sealed record CountPostResultDto(int CountId, CountStatus Status, int? Ad
 public sealed class CreateCountRequest
 {
     [Required] public int WarehouseId { get; set; }
+    /// <summary>Owning branch — warehouses are shared, so this is what actually scopes the
+    /// document (resolved via IBranchConfigService).</summary>
+    [Required] public int BranchId { get; set; }
     [Required, EnumDataType(typeof(CountType))] public CountType CountType { get; set; }
     [Required, MinLength(1)] public List<int> ItemIds { get; set; } = new();
 }

Backend/ERPCore/Dtos/Stock/TransferDtos.cs

@@ -9,12 +9,12 @@ public sealed record TransferLineDto(
     int TransferLineId, int ItemId, int? SrcBinId, int? DestBinId, int? BatchId, decimal Qty, decimal QtyReceived);
 
 public sealed record TransferDto(
-    int TransferId, string DocNo, int SrcWarehouseId, int DestWarehouseId,
+    int TransferId, string DocNo, int SrcWarehouseId, int DestWarehouseId, int BranchId,
     TransferStatus Status, int CreatedBy, DateTime CreatedAt, IReadOnlyList<TransferLineDto> Lines);
 
 /// <summary>Row shape for <c>GET /stock-transfers</c> — line count instead of the lines themselves.</summary>
 public sealed record TransferSummaryDto(
-    int TransferId, string DocNo, int SrcWarehouseId, int DestWarehouseId,
+    int TransferId, string DocNo, int SrcWarehouseId, int DestWarehouseId, int BranchId,
     TransferStatus Status, int CreatedBy, DateTime CreatedAt, int LineCount);
 
 public sealed record ConsumedLayerDto(int LayerId, decimal QtyConsumed, decimal UnitCost);
@@ -42,6 +42,9 @@ public sealed class CreateTransferRequest
 {
     [Required] public int SrcWarehouseId { get; set; }
     [Required] public int DestWarehouseId { get; set; }
+    /// <summary>Owning branch for this transfer — warehouses are shared, so this is what
+    /// actually scopes the document (resolved via IBranchConfigService).</summary>
+    [Required] public int BranchId { get; set; }
     [Required, MinLength(1)] public List<CreateTransferLineInput> Lines { get; set; } = new();
 }
 

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

@@ -22,11 +22,13 @@ public sealed class GrnConfiguration : IEntityTypeConfiguration<Grn>
         builder.HasOne(g => g.PurchaseOrder).WithMany().HasForeignKey(g => g.PoId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(g => g.Vendor).WithMany().HasForeignKey(g => g.VendorId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(g => g.Warehouse).WithMany().HasForeignKey(g => g.WarehouseId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(g => g.Branch).WithMany().HasForeignKey(g => g.BranchId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(g => g.Creator).WithMany().HasForeignKey(g => g.CreatedBy).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(g => g.PurchaseInvoice).WithMany().HasForeignKey(g => g.PurchaseInvoiceId).OnDelete(DeleteBehavior.Restrict);
 
         builder.HasIndex(g => g.Status);
         builder.HasIndex(g => g.PoId);
+        builder.HasIndex(g => g.BranchId);
     }
 }
 

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

@@ -30,6 +30,11 @@ public sealed class SalesInvoiceConfiguration : IEntityTypeConfiguration<SalesIn
             .HasForeignKey(x => x.WarehouseId)
             .OnDelete(DeleteBehavior.Restrict);
 
+        builder.HasOne(x => x.Branch)
+            .WithMany()
+            .HasForeignKey(x => x.BranchId)
+            .OnDelete(DeleteBehavior.Restrict);
+
         builder.Property(x => x.InvoiceType)
             .HasConversion<string>().HasMaxLength(20).IsRequired()
             .HasDefaultValue(SalesInvoiceType.B2C);
@@ -47,6 +52,7 @@ public sealed class SalesInvoiceConfiguration : IEntityTypeConfiguration<SalesIn
 
         builder.HasIndex(x => x.Status);
         builder.HasIndex(x => x.InvoiceDate);
+        builder.HasIndex(x => x.BranchId);
 
         builder.HasMany(x => x.Lines)
             .WithOne(x => x.SalesInvoice)

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

@@ -21,7 +21,10 @@ public sealed class StockAdjustmentConfiguration : IEntityTypeConfiguration<Stoc
 
         builder.HasOne(a => a.Warehouse).WithMany().HasForeignKey(a => a.WarehouseId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(a => a.ReasonCode).WithMany().HasForeignKey(a => a.ReasonCodeId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(a => a.Branch).WithMany().HasForeignKey(a => a.BranchId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(a => a.Creator).WithMany().HasForeignKey(a => a.CreatedBy).OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasIndex(a => a.BranchId);
     }
 }
 

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

@@ -20,9 +20,11 @@ public sealed class StockCountConfiguration : IEntityTypeConfiguration<StockCoun
         builder.Property(c => c.RowVersion).IsRowVersion();
 
         builder.HasOne(c => c.Warehouse).WithMany().HasForeignKey(c => c.WarehouseId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(c => c.Branch).WithMany().HasForeignKey(c => c.BranchId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(c => c.Creator).WithMany().HasForeignKey(c => c.CreatedBy).OnDelete(DeleteBehavior.Restrict);
 
         builder.HasIndex(c => c.Status);
+        builder.HasIndex(c => c.BranchId);
     }
 }
 

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

@@ -20,9 +20,11 @@ public sealed class StockTransferConfiguration : IEntityTypeConfiguration<StockT
 
         builder.HasOne(t => t.SrcWarehouse).WithMany().HasForeignKey(t => t.SrcWarehouseId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(t => t.DestWarehouse).WithMany().HasForeignKey(t => t.DestWarehouseId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(t => t.Branch).WithMany().HasForeignKey(t => t.BranchId).OnDelete(DeleteBehavior.Restrict);
         builder.HasOne(t => t.Creator).WithMany().HasForeignKey(t => t.CreatedBy).OnDelete(DeleteBehavior.Restrict);
 
         builder.HasIndex(t => t.Status);
+        builder.HasIndex(t => t.BranchId);
     }
 }
 

Backend/ERPCore/Migrations/20260908101847_AddBranchIdToDocuments.cs

@@ -0,0 +1,199 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ERPCore.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddBranchIdToDocuments : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "BranchId",
+                table: "stock_transfers",
+                type: "integer",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<int>(
+                name: "BranchId",
+                table: "stock_counts",
+                type: "integer",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<int>(
+                name: "BranchId",
+                table: "stock_adjustments",
+                type: "integer",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<int>(
+                name: "BranchId",
+                table: "sales_invoices",
+                type: "integer",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<int>(
+                name: "BranchId",
+                table: "grns",
+                type: "integer",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_stock_transfers_BranchId",
+                table: "stock_transfers",
+                column: "BranchId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_stock_counts_BranchId",
+                table: "stock_counts",
+                column: "BranchId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_stock_adjustments_BranchId",
+                table: "stock_adjustments",
+                column: "BranchId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_sales_invoices_BranchId",
+                table: "sales_invoices",
+                column: "BranchId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_grns_BranchId",
+                table: "grns",
+                column: "BranchId");
+
+            // Backfill from each document's existing warehouse — warehouses were the sole
+            // branch anchor until now, so this preserves current branch assignment exactly.
+            // (Warehouse.BranchId is NOT NULL, so every row is resolvable; the WHERE BranchId = 0
+            // guard just keeps this idempotent if the migration is ever re-run against partial state.)
+            migrationBuilder.Sql(@"
+                UPDATE grns g SET ""BranchId"" = w.""BranchId""
+                FROM warehouses w WHERE w.""WarehouseId"" = g.""WarehouseId"" AND g.""BranchId"" = 0;
+
+                UPDATE sales_invoices x SET ""BranchId"" = w.""BranchId""
+                FROM warehouses w WHERE w.""WarehouseId"" = x.""WarehouseId"" AND x.""BranchId"" = 0;
+
+                UPDATE stock_counts c SET ""BranchId"" = w.""BranchId""
+                FROM warehouses w WHERE w.""WarehouseId"" = c.""WarehouseId"" AND c.""BranchId"" = 0;
+
+                UPDATE stock_adjustments a SET ""BranchId"" = w.""BranchId""
+                FROM warehouses w WHERE w.""WarehouseId"" = a.""WarehouseId"" AND a.""BranchId"" = 0;
+
+                UPDATE stock_transfers t SET ""BranchId"" = w.""BranchId""
+                FROM warehouses w WHERE w.""WarehouseId"" = t.""SrcWarehouseId"" AND t.""BranchId"" = 0;
+            ");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_grns_hr_branches_BranchId",
+                table: "grns",
+                column: "BranchId",
+                principalTable: "hr_branches",
+                principalColumn: "BranchId",
+                onDelete: ReferentialAction.Restrict);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_sales_invoices_hr_branches_BranchId",
+                table: "sales_invoices",
+                column: "BranchId",
+                principalTable: "hr_branches",
+                principalColumn: "BranchId",
+                onDelete: ReferentialAction.Restrict);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_stock_adjustments_hr_branches_BranchId",
+                table: "stock_adjustments",
+                column: "BranchId",
+                principalTable: "hr_branches",
+                principalColumn: "BranchId",
+                onDelete: ReferentialAction.Restrict);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_stock_counts_hr_branches_BranchId",
+                table: "stock_counts",
+                column: "BranchId",
+                principalTable: "hr_branches",
+                principalColumn: "BranchId",
+                onDelete: ReferentialAction.Restrict);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_stock_transfers_hr_branches_BranchId",
+                table: "stock_transfers",
+                column: "BranchId",
+                principalTable: "hr_branches",
+                principalColumn: "BranchId",
+                onDelete: ReferentialAction.Restrict);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_grns_hr_branches_BranchId",
+                table: "grns");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_sales_invoices_hr_branches_BranchId",
+                table: "sales_invoices");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_stock_adjustments_hr_branches_BranchId",
+                table: "stock_adjustments");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_stock_counts_hr_branches_BranchId",
+                table: "stock_counts");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_stock_transfers_hr_branches_BranchId",
+                table: "stock_transfers");
+
+            migrationBuilder.DropIndex(
+                name: "IX_stock_transfers_BranchId",
+                table: "stock_transfers");
+
+            migrationBuilder.DropIndex(
+                name: "IX_stock_counts_BranchId",
+                table: "stock_counts");
+
+            migrationBuilder.DropIndex(
+                name: "IX_stock_adjustments_BranchId",
+                table: "stock_adjustments");
+
+            migrationBuilder.DropIndex(
+                name: "IX_sales_invoices_BranchId",
+                table: "sales_invoices");
+
+            migrationBuilder.DropIndex(
+                name: "IX_grns_BranchId",
+                table: "grns");
+
+            migrationBuilder.DropColumn(
+                name: "BranchId",
+                table: "stock_transfers");
+
+            migrationBuilder.DropColumn(
+                name: "BranchId",
+                table: "stock_counts");
+
+            migrationBuilder.DropColumn(
+                name: "BranchId",
+                table: "stock_adjustments");
+
+            migrationBuilder.DropColumn(
+                name: "BranchId",
+                table: "sales_invoices");
+
+            migrationBuilder.DropColumn(
+                name: "BranchId",
+                table: "grns");
+        }
+    }
+}

Backend/ERPCore/Migrations/ErpDbContextModelSnapshot.cs

@@ -1447,6 +1447,9 @@ namespace ERPCore.Migrations
 
                     NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("GrnId"));
 
+                    b.Property<int>("BranchId")
+                        .HasColumnType("integer");
+
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("timestamp with time zone");
 
@@ -1493,6 +1496,8 @@ namespace ERPCore.Migrations
 
                     b.HasKey("GrnId");
 
+                    b.HasIndex("BranchId");
+
                     b.HasIndex("CreatedBy");
 
                     b.HasIndex("DocNo")
@@ -4187,6 +4192,9 @@ namespace ERPCore.Migrations
                         .HasPrecision(18, 4)
                         .HasColumnType("numeric(18,4)");
 
+                    b.Property<int>("BranchId")
+                        .HasColumnType("integer");
+
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("timestamp with time zone");
 
@@ -4279,6 +4287,8 @@ namespace ERPCore.Migrations
 
                     b.HasKey("SalesInvoiceId");
 
+                    b.HasIndex("BranchId");
+
                     b.HasIndex("CreatorUserId");
 
                     b.HasIndex("CustomerId");
@@ -4859,6 +4869,9 @@ namespace ERPCore.Migrations
 
                     NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("AdjustmentId"));
 
+                    b.Property<int>("BranchId")
+                        .HasColumnType("integer");
+
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("timestamp with time zone");
 
@@ -4896,6 +4909,8 @@ namespace ERPCore.Migrations
 
                     b.HasKey("AdjustmentId");
 
+                    b.HasIndex("BranchId");
+
                     b.HasIndex("CreatedBy");
 
                     b.HasIndex("DocNo")
@@ -4958,6 +4973,9 @@ namespace ERPCore.Migrations
 
                     NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("CountId"));
 
+                    b.Property<int>("BranchId")
+                        .HasColumnType("integer");
+
                     b.Property<string>("CountType")
                         .IsRequired()
                         .HasMaxLength(20)
@@ -4990,6 +5008,8 @@ namespace ERPCore.Migrations
 
                     b.HasKey("CountId");
 
+                    b.HasIndex("BranchId");
+
                     b.HasIndex("CreatedBy");
 
                     b.HasIndex("DocNo")
@@ -5182,6 +5202,9 @@ namespace ERPCore.Migrations
 
                     NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("TransferId"));
 
+                    b.Property<int>("BranchId")
+                        .HasColumnType("integer");
+
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("timestamp with time zone");
 
@@ -5212,6 +5235,8 @@ namespace ERPCore.Migrations
 
                     b.HasKey("TransferId");
 
+                    b.HasIndex("BranchId");
+
                     b.HasIndex("CreatedBy");
 
                     b.HasIndex("DestWarehouseId");
@@ -6380,6 +6405,12 @@ namespace ERPCore.Migrations
 
             modelBuilder.Entity("ERPCore.Domain.Entities.Grn", b =>
                 {
+                    b.HasOne("ERPCore.Domain.Entities.Branch", "Branch")
+                        .WithMany()
+                        .HasForeignKey("BranchId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
                     b.HasOne("ERPCore.Domain.Entities.User", "Creator")
                         .WithMany()
                         .HasForeignKey("CreatedBy")
@@ -6408,6 +6439,8 @@ namespace ERPCore.Migrations
                         .OnDelete(DeleteBehavior.Restrict)
                         .IsRequired();
 
+                    b.Navigation("Branch");
+
                     b.Navigation("Creator");
 
                     b.Navigation("PurchaseInvoice");
@@ -7142,6 +7175,12 @@ namespace ERPCore.Migrations
 
             modelBuilder.Entity("ERPCore.Domain.Entities.SalesInvoice", b =>
                 {
+                    b.HasOne("ERPCore.Domain.Entities.Branch", "Branch")
+                        .WithMany()
+                        .HasForeignKey("BranchId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
                     b.HasOne("ERPCore.Domain.Entities.User", "Creator")
                         .WithMany()
                         .HasForeignKey("CreatorUserId");
@@ -7158,6 +7197,8 @@ namespace ERPCore.Migrations
                         .OnDelete(DeleteBehavior.Restrict)
                         .IsRequired();
 
+                    b.Navigation("Branch");
+
                     b.Navigation("Creator");
 
                     b.Navigation("Customer");
@@ -7423,6 +7464,12 @@ namespace ERPCore.Migrations
 
             modelBuilder.Entity("ERPCore.Domain.Entities.StockAdjustment", b =>
                 {
+                    b.HasOne("ERPCore.Domain.Entities.Branch", "Branch")
+                        .WithMany()
+                        .HasForeignKey("BranchId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
                     b.HasOne("ERPCore.Domain.Entities.User", "Creator")
                         .WithMany()
                         .HasForeignKey("CreatedBy")
@@ -7441,6 +7488,8 @@ namespace ERPCore.Migrations
                         .OnDelete(DeleteBehavior.Restrict)
                         .IsRequired();
 
+                    b.Navigation("Branch");
+
                     b.Navigation("Creator");
 
                     b.Navigation("ReasonCode");
@@ -7484,6 +7533,12 @@ namespace ERPCore.Migrations
 
             modelBuilder.Entity("ERPCore.Domain.Entities.StockCount", b =>
                 {
+                    b.HasOne("ERPCore.Domain.Entities.Branch", "Branch")
+                        .WithMany()
+                        .HasForeignKey("BranchId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
                     b.HasOne("ERPCore.Domain.Entities.User", "Creator")
                         .WithMany()
                         .HasForeignKey("CreatedBy")
@@ -7496,6 +7551,8 @@ namespace ERPCore.Migrations
                         .OnDelete(DeleteBehavior.Restrict)
                         .IsRequired();
 
+                    b.Navigation("Branch");
+
                     b.Navigation("Creator");
 
                     b.Navigation("Warehouse");
@@ -7603,6 +7660,12 @@ namespace ERPCore.Migrations
 
             modelBuilder.Entity("ERPCore.Domain.Entities.StockTransfer", b =>
                 {
+                    b.HasOne("ERPCore.Domain.Entities.Branch", "Branch")
+                        .WithMany()
+                        .HasForeignKey("BranchId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
                     b.HasOne("ERPCore.Domain.Entities.User", "Creator")
                         .WithMany()
                         .HasForeignKey("CreatedBy")
@@ -7621,6 +7684,8 @@ namespace ERPCore.Migrations
                         .OnDelete(DeleteBehavior.Restrict)
                         .IsRequired();
 
+                    b.Navigation("Branch");
+
                     b.Navigation("Creator");
 
                     b.Navigation("DestWarehouse");

Backend/ERPCore/Services/AdjustmentService.cs

@@ -32,6 +32,7 @@ public sealed class AdjustmentService : IAdjustmentService
     private readonly IStockMutator _mutator;
     private readonly INumberSequenceService _numbers;
     private readonly ICurrentUser _currentUser;
+    private readonly IBranchConfigService _branchConfig;
     private readonly IUnitOfWork _uow;
     private readonly IGeneralLedgerService _gl;
     private readonly string _glInventoryAccountCode;
@@ -41,7 +42,7 @@ public sealed class AdjustmentService : IAdjustmentService
     public AdjustmentService(
         IRepository<StockAdjustment> adjustments, IRepository<Warehouse> warehouses, IRepository<Item> items,
         IRepository<ReasonCode> reasonCodes, IRepository<StockLedger> ledger, IStockMutator mutator,
-        INumberSequenceService numbers, ICurrentUser currentUser, IUnitOfWork uow,
+        INumberSequenceService numbers, ICurrentUser currentUser, IBranchConfigService branchConfig, IUnitOfWork uow,
         IGeneralLedgerService gl, IConfiguration configuration)
     {
         _adjustments = adjustments;
@@ -52,6 +53,7 @@ public sealed class AdjustmentService : IAdjustmentService
         _mutator = mutator;
         _numbers = numbers;
         _currentUser = currentUser;
+        _branchConfig = branchConfig;
         _uow = uow;
         _gl = gl;
         _glInventoryAccountCode = configuration["Adjustment:GlInventoryAccountCode"] ?? string.Empty;
@@ -105,14 +107,15 @@ public sealed class AdjustmentService : IAdjustmentService
             q = q.Where(a => EF.Functions.ILike(a.DocNo, $"%{term}%"));
         }
         if (warehouseId is not null) q = q.Where(a => a.WarehouseId == warehouseId);
-        if (branchId is not null) q = q.Where(a => a.Warehouse!.BranchId == branchId);
+        // Warehouses are shared across branches — the adjustment carries its own owning BranchId.
+        if (branchId is not null) q = q.Where(a => a.BranchId == branchId);
         if (reasonCodeId is not null) q = q.Where(a => a.ReasonCodeId == reasonCodeId);
 
         var total = await q.CountAsync(ct);
         var rows = await q.OrderByDescending(a => a.AdjustmentId)
             .Skip(query.Skip).Take(query.PageSize)
             .Select(a => new AdjustmentSummaryDto(
-                a.AdjustmentId, a.DocNo, a.WarehouseId, a.ReasonCodeId, a.Status,
+                a.AdjustmentId, a.DocNo, a.WarehouseId, a.BranchId, a.ReasonCodeId, a.Status,
                 a.CreatedBy, a.CreatedAt, a.Lines.Count, a.GlJournalNo))
             .ToListAsync(ct);
 
@@ -145,6 +148,8 @@ public sealed class AdjustmentService : IAdjustmentService
         if (!await _warehouses.Query().AnyAsync(w => w.WarehouseId == request.WarehouseId, ct))
             throw new DomainException(ErrorCodes.Validation, $"Warehouse {request.WarehouseId} does not exist.", 422);
 
+        var branchId = await _branchConfig.ResolveBranchIdAsync(request.BranchId, ct);
+
         var reason = await _reasonCodes.Query().AsNoTracking().FirstOrDefaultAsync(r => r.ReasonCodeId == request.ReasonCodeId, ct)
             ?? throw new DomainException(ErrorCodes.Validation, $"Reason code {request.ReasonCodeId} does not exist.", 422);
         if (reason.Context != ReasonContext.Adjustment)
@@ -169,6 +174,7 @@ public sealed class AdjustmentService : IAdjustmentService
             {
                 DocNo = docNo,
                 WarehouseId = request.WarehouseId,
+                BranchId = branchId,
                 ReasonCodeId = request.ReasonCodeId.Value,
                 Status = AdjustmentStatus.Posted,
                 CreatedBy = _currentUser.AuditUserId,
@@ -196,7 +202,7 @@ public sealed class AdjustmentService : IAdjustmentService
     }
 
     private static AdjustmentDto ToDto(StockAdjustment a, IReadOnlyList<int> ledgerRefs) => new(
-        a.AdjustmentId, a.DocNo, a.WarehouseId, a.ReasonCodeId, a.Status, a.CreatedBy, a.CreatedAt,
+        a.AdjustmentId, a.DocNo, a.WarehouseId, a.BranchId, a.ReasonCodeId, a.Status, a.CreatedBy, a.CreatedAt,
         a.GlJournalNo, a.GlPostedAt,
         a.Lines.OrderBy(l => l.AdjLineId)
             .Select(l => new AdjustmentLineDto(l.AdjLineId, l.ItemId, l.BinId, l.BatchId, l.QtyDelta)).ToList(),

Backend/ERPCore/Services/CountService.cs

@@ -34,6 +34,7 @@ public sealed class CountService : ICountService
     private readonly IStockMutator _mutator;
     private readonly INumberSequenceService _numbers;
     private readonly ICurrentUser _currentUser;
+    private readonly IBranchConfigService _branchConfig;
     private readonly IUnitOfWork _uow;
     private readonly IGeneralLedgerService _gl;
     private readonly string _glInventoryAccountCode;
@@ -43,7 +44,7 @@ public sealed class CountService : ICountService
     public CountService(
         IRepository<StockCount> counts, IRepository<StockAdjustment> adjustments, IRepository<Warehouse> warehouses,
         IRepository<Item> items, IRepository<ReasonCode> reasonCodes, IFifoCostingService fifo, IStockMutator mutator,
-        INumberSequenceService numbers, ICurrentUser currentUser, IUnitOfWork uow,
+        INumberSequenceService numbers, ICurrentUser currentUser, IBranchConfigService branchConfig, IUnitOfWork uow,
         IGeneralLedgerService gl, IConfiguration configuration)
     {
         _counts = counts;
@@ -55,6 +56,7 @@ public sealed class CountService : ICountService
         _mutator = mutator;
         _numbers = numbers;
         _currentUser = currentUser;
+        _branchConfig = branchConfig;
         _uow = uow;
         _gl = gl;
         _glInventoryAccountCode = configuration["Adjustment:GlInventoryAccountCode"] ?? string.Empty;
@@ -108,13 +110,14 @@ public sealed class CountService : ICountService
         }
         if (status is not null) q = q.Where(c => c.Status == status);
         if (warehouseId is not null) q = q.Where(c => c.WarehouseId == warehouseId);
-        if (branchId is not null) q = q.Where(c => c.Warehouse!.BranchId == branchId);
+        // Warehouses are shared across branches — the count carries its own owning BranchId.
+        if (branchId is not null) q = q.Where(c => c.BranchId == branchId);
 
         var total = await q.CountAsync(ct);
         var rows = await q.OrderByDescending(c => c.CountId)
             .Skip(query.Skip).Take(query.PageSize)
             .Select(c => new CountSummaryDto(
-                c.CountId, c.DocNo, c.WarehouseId, c.CountType, c.Status,
+                c.CountId, c.DocNo, c.WarehouseId, c.BranchId, c.CountType, c.Status,
                 c.CreatedBy, c.CreatedAt, c.Lines.Count))
             .ToListAsync(ct);
 
@@ -133,6 +136,8 @@ public sealed class CountService : ICountService
         if (!await _warehouses.Query().AnyAsync(w => w.WarehouseId == request.WarehouseId, ct))
             throw new DomainException(ErrorCodes.Validation, $"Warehouse {request.WarehouseId} does not exist.", 422);
 
+        var branchId = await _branchConfig.ResolveBranchIdAsync(request.BranchId, ct);
+
         var itemIds = request.ItemIds.Distinct().ToList();
         foreach (var id in itemIds)
             if (!await _items.Query().AnyAsync(i => i.ItemId == id, ct))
@@ -153,6 +158,7 @@ public sealed class CountService : ICountService
             {
                 DocNo = docNo,
                 WarehouseId = request.WarehouseId,
+                BranchId = branchId,
                 CountType = request.CountType,
                 Status = CountStatus.Draft,
                 CreatedBy = _currentUser.AuditUserId,
@@ -222,6 +228,7 @@ public sealed class CountService : ICountService
             {
                 DocNo = docNo,
                 WarehouseId = count.WarehouseId,
+                BranchId = count.BranchId,
                 ReasonCodeId = reason.ReasonCodeId,
                 Status = AdjustmentStatus.Posted,
                 CreatedBy = _currentUser.AuditUserId,
@@ -250,7 +257,7 @@ public sealed class CountService : ICountService
     }
 
     private static CountDto Map(StockCount c) => new(
-        c.CountId, c.DocNo, c.WarehouseId, c.CountType, c.Status, c.CreatedBy, c.CreatedAt,
+        c.CountId, c.DocNo, c.WarehouseId, c.BranchId, c.CountType, c.Status, c.CreatedBy, c.CreatedAt,
         c.Lines.OrderBy(l => l.CountLineId)
             .Select(l => new CountLineDto(l.CountLineId, l.ItemId, l.BinId, l.SystemQty, l.CountedQty, l.Variance)).ToList());
 }

Backend/ERPCore/Services/DashboardService.cs

@@ -62,11 +62,11 @@ public sealed class DashboardService : IDashboardService
             .ToList();
 
         var grns = _grns.Query().AsNoTracking();
-        if (branchId is not null) grns = grns.Where(g => g.Warehouse!.BranchId == branchId);
+        if (branchId is not null) grns = grns.Where(g => g.BranchId == branchId);
         var pendingGrns = await grns.CountAsync(g => g.Status == GrnStatus.Draft, ct);
 
         var counts = _counts.Query().AsNoTracking();
-        if (branchId is not null) counts = counts.Where(c => c.Warehouse!.BranchId == branchId);
+        if (branchId is not null) counts = counts.Where(c => c.BranchId == branchId);
         var pendingCounts = await counts.CountAsync(c => c.Status == CountStatus.Counted, ct);
 
         // PurchaseOrder/Requisition/Rfq carry no warehouse/branch at header level yet

Backend/ERPCore/Services/GrnService.cs

@@ -38,6 +38,7 @@ public sealed class GrnService : IGrnService
     private readonly IFifoCostingService _fifo;
     private readonly INumberSequenceService _numbers;
     private readonly ICurrentUser _currentUser;
+    private readonly IBranchConfigService _branchConfig;
     private readonly IUnitOfWork _uow;
     private readonly IGeneralLedgerService _gl;
     private readonly string _glInventoryAccountCode;
@@ -49,8 +50,8 @@ public sealed class GrnService : IGrnService
         IRepository<Item> items, IRepository<Warehouse> warehouses,
         IRepository<Bin> bins, IRepository<Vendor> vendors, IRepository<Batch> batches,
         IRepository<StockLayer> layers, IRepository<StockLedger> ledger,
-        IFifoCostingService fifo, INumberSequenceService numbers, ICurrentUser currentUser, IUnitOfWork uow,
-        IGeneralLedgerService gl, IConfiguration configuration)
+        IFifoCostingService fifo, INumberSequenceService numbers, ICurrentUser currentUser, IBranchConfigService branchConfig,
+        IUnitOfWork uow, IGeneralLedgerService gl, IConfiguration configuration)
     {
         _grns = grns;
         _pos = pos;
@@ -65,6 +66,7 @@ public sealed class GrnService : IGrnService
         _fifo = fifo;
         _numbers = numbers;
         _currentUser = currentUser;
+        _branchConfig = branchConfig;
         _uow = uow;
         _gl = gl;
         _glInventoryAccountCode = configuration["Grn:GlInventoryAccountCode"] ?? string.Empty;
@@ -86,15 +88,14 @@ public sealed class GrnService : IGrnService
         if (poId is not null) q = q.Where(g => g.PoId == poId);
         if (vendorId is not null) q = q.Where(g => g.VendorId == vendorId);
         if (warehouseId is not null) q = q.Where(g => g.WarehouseId == warehouseId);
-        // GRN carries no BranchId of its own — it inherits branch scope transitively via its
-        // Warehouse, same as Sales (docs/BRANCH_ISOLATION_PLAN.md "Anchor mechanism").
-        if (branchId is not null) q = q.Where(g => g.Warehouse!.BranchId == branchId);
+        // Warehouses are shared across branches — GRN carries its own BranchId, set at creation.
+        if (branchId is not null) q = q.Where(g => g.BranchId == branchId);
 
         var total = await q.CountAsync(ct);
         var rows = await q.OrderByDescending(g => g.GrnId)
             .Skip(query.Skip).Take(query.PageSize)
             .Select(g => new GrnSummaryDto(
-                g.GrnId, g.DocNo, g.PoId, g.VendorId, g.WarehouseId, g.Status,
+                g.GrnId, g.DocNo, g.PoId, g.VendorId, g.WarehouseId, g.BranchId, g.Status,
                 g.CreatedBy, g.CreatedAt, g.PostedAt, g.Lines.Count,
                 g.PurchaseInvoiceId, g.PurchaseInvoice != null ? g.PurchaseInvoice.DocNo : null))
             .ToListAsync(ct);
@@ -116,6 +117,8 @@ public sealed class GrnService : IGrnService
         if (!await _warehouses.Query().AnyAsync(w => w.WarehouseId == request.WarehouseId, ct))
             throw new DomainException(ErrorCodes.Validation, $"Warehouse {request.WarehouseId} does not exist.", 422);
 
+        var branchId = await _branchConfig.ResolveBranchIdAsync(request.BranchId, ct);
+
         // Resolve vendor + PO context.
         PurchaseOrder? po = null;
         int vendorId;
@@ -211,6 +214,7 @@ public sealed class GrnService : IGrnService
                 PoId = request.PoId,
                 VendorId = vendorId,
                 WarehouseId = request.WarehouseId,
+                BranchId = branchId,
                 Status = GrnStatus.Draft,
                 CreatedBy = _currentUser.AuditUserId,
                 CreatedAt = DateTime.UtcNow,
@@ -448,7 +452,7 @@ public sealed class GrnService : IGrnService
         l.LayerId, l.ItemId, l.WarehouseId, l.BatchId, l.QtyReceived, l.QtyRemaining, l.UnitCost, l.ReceiptDate);
 
     private static GrnDto Map(Grn g) => new(
-        g.GrnId, g.DocNo, g.PoId, g.VendorId, g.WarehouseId, g.Status, g.CreatedBy, g.CreatedAt, g.PostedAt,
+        g.GrnId, g.DocNo, g.PoId, g.VendorId, g.WarehouseId, g.BranchId, g.Status, g.CreatedBy, g.CreatedAt, g.PostedAt,
         g.GlJournalNo, g.PurchaseInvoiceId, g.PurchaseInvoice?.DocNo,
         g.Lines.OrderBy(l => l.GrnLineId).Select(l => new GrnLineDto(
             l.GrnLineId, l.PoLineId, l.ItemId, l.BinId, l.Qty, l.UnitCost, l.PoUnitPrice,

Backend/ERPCore/Services/SalesInvoiceService.cs

@@ -26,6 +26,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
     private readonly ISalesMappingService _mapping;
     private readonly ISalesDocumentWorkflowService _workflow;
     private readonly ICurrentUser _currentUser;
+    private readonly IBranchConfigService _branchConfig;
     private readonly INumberSequenceService _numbers;
     private readonly IUnitOfWork _uow;
 
@@ -33,7 +34,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         IRepository<SalesInvoice> invoices, IRepository<Customer> customers, IRepository<Item> items,
         IRepository<Uom> uoms, IRepository<Warehouse> warehouses, ISalesDomainService sales, ISalesPostingService posting, ISalesMappingService mapping,
         ISalesDocumentWorkflowService workflow,
-        ICurrentUser currentUser, INumberSequenceService numbers, IUnitOfWork uow)
+        ICurrentUser currentUser, IBranchConfigService branchConfig, INumberSequenceService numbers, IUnitOfWork uow)
     {
         _invoices = invoices;
         _customers = customers;
@@ -45,6 +46,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         _mapping = mapping;
         _workflow = workflow;
         _currentUser = currentUser;
+        _branchConfig = branchConfig;
         _numbers = numbers;
         _uow = uow;
     }
@@ -60,9 +62,8 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         if (status is not null) q = q.Where(x => x.Status == status);
         if (customerId is not null) q = q.Where(x => x.CustomerId == customerId);
         if (warehouseId is not null) q = q.Where(x => x.WarehouseId == warehouseId);
-        // Sales carries no BranchId of its own — it inherits branch scope transitively via
-        // its Warehouse (docs/BRANCH_ISOLATION_PLAN.md "Anchor mechanism: Warehouse carries the branch").
-        if (branchId is not null) q = q.Where(x => x.Warehouse!.BranchId == branchId);
+        // Warehouses are shared across branches — the invoice carries its own owning BranchId.
+        if (branchId is not null) q = q.Where(x => x.BranchId == branchId);
 
         var total = await q.CountAsync(ct);
         var rows = await q.OrderByDescending(x => x.SalesInvoiceId).Skip(query.Skip).Take(query.PageSize).ToListAsync(ct);
@@ -83,6 +84,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
     public async Task<ETagged<SalesInvoiceDto>> CreateAsync(CreateSalesInvoiceRequest request, CancellationToken ct = default)
     {
         await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, null, false, ct);
+        var branchId = await _branchConfig.ResolveBranchIdAsync(request.BranchId, ct);
 
         var customerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
         var customerSnapshotTaxNo = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.TaxRegistrationNo).FirstAsync(ct);
@@ -96,6 +98,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
                 InvoiceDate = DateTime.UtcNow,
                 CustomerId = request.CustomerId,
                 WarehouseId = request.WarehouseId,
+                BranchId = branchId,
                 InvoiceType = request.InvoiceType,
                 Status = SalesInvoiceStatus.Draft,
                 CreatedBy = _currentUser.AuditUserId,
@@ -119,6 +122,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, null, false, ct);
         invoice.CustomerId = request.CustomerId;
         invoice.WarehouseId = request.WarehouseId;
+        invoice.BranchId = await _branchConfig.ResolveBranchIdAsync(request.BranchId, ct);
         invoice.InvoiceType = request.InvoiceType;
         invoice.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
         invoice.CustomerSnapshotTaxNo = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.TaxRegistrationNo).FirstAsync(ct);
@@ -201,5 +205,5 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
 
     private SalesInvoiceSummaryDto MapSummary(SalesInvoice x) => new(
         x.SalesInvoiceId, x.InvoiceNo, x.InvoiceDate, x.CustomerId, x.CustomerSnapshotName,
-        x.WarehouseId, x.InvoiceType, x.Status, _mapping.MapInvoiceTotals(x), x.CreatedAt, x.GlJournalNo);
+        x.WarehouseId, x.BranchId, x.InvoiceType, x.Status, _mapping.MapInvoiceTotals(x), x.CreatedAt, x.GlJournalNo);
 }

Backend/ERPCore/Services/SalesMappingService.cs

@@ -31,7 +31,7 @@ public sealed class SalesMappingService : ISalesMappingService
     public SalesInvoiceDto MapInvoice(SalesInvoice invoice)
         => new(
             invoice.SalesInvoiceId, invoice.InvoiceNo, invoice.InvoiceDate, invoice.CustomerId,
-            invoice.CustomerSnapshotName, invoice.CustomerSnapshotTaxNo, invoice.WarehouseId,
+            invoice.CustomerSnapshotName, invoice.CustomerSnapshotTaxNo, invoice.WarehouseId, invoice.BranchId,
             invoice.InvoiceType, invoice.Status, invoice.CreatedBy, invoice.CreatedAt, invoice.UpdatedAt,
             invoice.GlJournalNo, invoice.GlPostedAt,
             MapInvoiceTotals(invoice),

Backend/ERPCore/Services/TransferService.cs

@@ -34,11 +34,13 @@ public sealed class TransferService : ITransferService
     private readonly IFifoCostingService _fifo;
     private readonly INumberSequenceService _numbers;
     private readonly ICurrentUser _currentUser;
+    private readonly IBranchConfigService _branchConfig;
     private readonly IUnitOfWork _uow;
 
     public TransferService(
         IRepository<StockTransfer> transfers, IRepository<Warehouse> warehouses, IRepository<Item> items,
-        IFifoCostingService fifo, INumberSequenceService numbers, ICurrentUser currentUser, IUnitOfWork uow)
+        IFifoCostingService fifo, INumberSequenceService numbers, ICurrentUser currentUser,
+        IBranchConfigService branchConfig, IUnitOfWork uow)
     {
         _transfers = transfers;
         _warehouses = warehouses;
@@ -46,6 +48,7 @@ public sealed class TransferService : ITransferService
         _fifo = fifo;
         _numbers = numbers;
         _currentUser = currentUser;
+        _branchConfig = branchConfig;
         _uow = uow;
     }
 
@@ -62,15 +65,14 @@ public sealed class TransferService : ITransferService
         if (status is not null) q = q.Where(t => t.Status == status);
         if (srcWarehouseId is not null) q = q.Where(t => t.SrcWarehouseId == srcWarehouseId);
         if (destWarehouseId is not null) q = q.Where(t => t.DestWarehouseId == destWarehouseId);
-        // A transfer touches two branches when it crosses one — show it on either side
-        // rather than only the branch that happens to hold the source warehouse.
-        if (branchId is not null) q = q.Where(t => t.SrcWarehouse!.BranchId == branchId || t.DestWarehouse!.BranchId == branchId);
+        // Warehouses are shared across branches — the transfer carries its own owning BranchId.
+        if (branchId is not null) q = q.Where(t => t.BranchId == branchId);
 
         var total = await q.CountAsync(ct);
         var rows = await q.OrderByDescending(t => t.TransferId)
             .Skip(query.Skip).Take(query.PageSize)
             .Select(t => new TransferSummaryDto(
-                t.TransferId, t.DocNo, t.SrcWarehouseId, t.DestWarehouseId, t.Status,
+                t.TransferId, t.DocNo, t.SrcWarehouseId, t.DestWarehouseId, t.BranchId, t.Status,
                 t.CreatedBy, t.CreatedAt, t.Lines.Count))
             .ToListAsync(ct);
 
@@ -90,6 +92,7 @@ public sealed class TransferService : ITransferService
             throw new DomainException(ErrorCodes.Validation, "destWarehouseId must differ from srcWarehouseId.", 422);
         await EnsureWarehouseAsync(request.SrcWarehouseId, ct);
         await EnsureWarehouseAsync(request.DestWarehouseId, ct);
+        var branchId = await _branchConfig.ResolveBranchIdAsync(request.BranchId, ct);
         foreach (var line in request.Lines)
             if (!await _items.Query().AnyAsync(i => i.ItemId == line.ItemId, ct))
                 throw new DomainException(ErrorCodes.Validation, $"Item {line.ItemId} does not exist.", 422);
@@ -103,6 +106,7 @@ public sealed class TransferService : ITransferService
                 DocNo = docNo,
                 SrcWarehouseId = request.SrcWarehouseId,
                 DestWarehouseId = request.DestWarehouseId,
+                BranchId = branchId,
                 Status = TransferStatus.Draft,
                 CreatedBy = actor,
                 CreatedAt = DateTime.UtcNow,
@@ -227,7 +231,7 @@ public sealed class TransferService : ITransferService
     }
 
     private static TransferDto Map(StockTransfer t) => new(
-        t.TransferId, t.DocNo, t.SrcWarehouseId, t.DestWarehouseId, t.Status, t.CreatedBy, t.CreatedAt,
+        t.TransferId, t.DocNo, t.SrcWarehouseId, t.DestWarehouseId, t.BranchId, t.Status, t.CreatedBy, t.CreatedAt,
         t.Lines.OrderBy(l => l.TransferLineId).Select(l => new TransferLineDto(
             l.TransferLineId, l.ItemId, l.SrcBinId, l.DestBinId, l.BatchId, l.Qty, l.QtyReceived)).ToList());
 }

Frontend/erp-system/app/dashboard/receiving/grn/new/page.tsx

@@ -1,6 +1,6 @@
 "use client"
 
-import { useEffect, useMemo, useState } from "react"
+import { useEffect, useState } from "react"
 import { useRouter } from "next/navigation"
 import Link from "next/link"
 import { ArrowLeft, ExternalLink, Plus, RefreshCw, ShieldCheck, Trash2 } from "lucide-react"
@@ -265,17 +265,10 @@ export default function NewGrnPage() {
   // branch to pin to and the Admin must pick one explicitly for this GRN.
   const lockedBranchId = isAdmin ? activeBranchId : myBranchId
   const showBranchPicker = branchingEnabled && isAdmin && !lockedBranchId
+  // The branch this GRN is being raised for — no longer used to filter warehouses
+  // (warehouses are shared infrastructure across branches), only to scope the document itself.
   const effectiveBranchId = branchingEnabled ? (isAdmin ? (activeBranchId ?? branchFilterId) : myBranchId) : null
-  const visibleWarehouses = useMemo(
-    () => (effectiveBranchId === null ? (warehouses ?? []) : (warehouses ?? []).filter((w) => w.branchId === effectiveBranchId)),
-    [warehouses, effectiveBranchId]
-  )
-
-  // Switching branch can strip the currently-picked warehouse out of the visible set —
-  // clear it rather than silently submitting a warehouse from the previous branch.
-  useEffect(() => {
-    setWarehouseId((prev) => (prev !== null && !visibleWarehouses.some((w) => w.warehouseId === prev) ? null : prev))
-  }, [visibleWarehouses])
+  const visibleWarehouses = warehouses ?? []
 
   function switchMode(next: Mode) {
     setMode(next)
@@ -459,6 +452,10 @@ export default function NewGrnPage() {
       setHeaderError("Select a purchase order.")
       return
     }
+    if (branchingEnabled && !effectiveBranchId) {
+      setHeaderError("Select a branch for this GRN.")
+      return
+    }
     if (lines.length === 0) {
       setSubmitError("Add at least one line.")
       return
@@ -513,6 +510,7 @@ export default function NewGrnPage() {
         poId: mode === "po" ? poId : null,
         vendorId: mode === "direct" ? vendorId : null,
         warehouseId: warehouseId as number,
+        branchId: effectiveBranchId ?? 0,
         lines: payloadLines,
       })
       toast.success("GRN created", `${grn.docNo} is ready to confirm.`)

Frontend/erp-system/types/grn.ts

@@ -61,6 +61,8 @@ export interface CreateGrnRequest {
   /** Required when poId is null (direct/emergency receipt, FR-GRN-02). */
   vendorId?: number | null
   warehouseId: number
+  /** Owning branch — warehouses are shared across branches, so this is what actually scopes the GRN. */
+  branchId: number
   lines: CreateGrnLineInput[]
 }
 
@@ -96,6 +98,7 @@ export interface Grn {
   poId: number | null
   vendorId: number
   warehouseId: number
+  branchId: number
   status: GrnStatus
   createdBy: number
   createdAt: string
@@ -116,6 +119,7 @@ export interface GrnSummary {
   poId: number | null
   vendorId: number
   warehouseId: number
+  branchId: number
   status: GrnStatus
   createdBy: number
   createdAt: string