Add GRN batch and serial tracking

Distribution/Data/AppDBContext.cs

@@ -303,6 +303,13 @@ public class AppDBContext(DbContextOptions<AppDBContext> options) : DbContext(op
             .HasForeignKey(gr => gr.FK_PurchaseOrderId)
             .OnDelete(DeleteBehavior.Restrict);
 
+        modelBuilder.Entity<GoodsReceipt>()
+            .HasOne(gr => gr.Supplier)
+            .WithMany()
+            .HasForeignKey(gr => gr.FK_SupplierId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
         modelBuilder.Entity<GoodsReceipt>()
             .HasOne(gr => gr.Warehouse)
             .WithMany()
@@ -321,6 +328,13 @@ public class AppDBContext(DbContextOptions<AppDBContext> options) : DbContext(op
             .HasForeignKey(i => i.FK_PurchaseOrderItemId)
             .OnDelete(DeleteBehavior.Restrict);
 
+        modelBuilder.Entity<GoodsReceiptItem>()
+            .HasOne(i => i.Item)
+            .WithMany()
+            .HasForeignKey(i => i.FK_ItemId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
         modelBuilder.Entity<GoodsReceiptItem>()
             .HasIndex(i => i.FK_GoodsReceiptId);
 

Distribution/Features/Grn/GrnController.cs

@@ -39,6 +39,20 @@ public class GrnController(GrnService service, ICurrentUserService currentUser)
         catch (InvalidOperationException ex) { return Conflict(new { error = ex.Message }); }
     }
 
+    /// <summary>Goods received without a purchase order.</summary>
+    [HttpPost("api/goods-receipts/direct")]
+    public async Task<IActionResult> CreateDirect(CreateDirectGrnRequest request, CancellationToken ct)
+    {
+        var userId = currentUser.UserId ?? request.ReceivedByUserId;
+        if (userId is null) return BadRequest(new { error = "ReceivedByUserId is required while auth is unavailable" });
+        try
+        {
+            var result = await service.CreateDirectAsync(request, userId.Value, ct);
+            return CreatedAtAction(nameof(GetById), new { id = result.Id }, result);
+        }
+        catch (InvalidOperationException ex) { return Conflict(new { error = ex.Message }); }
+    }
+
     [HttpGet("api/purchase-orders/{id:guid}/goods-receipts")]
     public async Task<IActionResult> GetByPurchaseOrder(Guid id) =>
         Ok(await service.GetByPurchaseOrderIdAsync(id));

Distribution/Features/Grn/GrnDTOs.cs

@@ -1,6 +1,19 @@
 namespace Distribution.Features.Grn;
 
-public record GrnItemRequest(Guid PurchaseOrderItemId, int AcceptedQuantity, int RejectedQuantity);
+/// <summary>BatchNumber is null for an expiry-only lot (TracksExpiryDate without TracksBatches).</summary>
+public record GrnBatchLineRequest(string? BatchNumber, DateTime? ExpiryDate, int Quantity);
+
+public record GrnItemRequest(
+    // Set for a PO-based receipt; null for a direct receipt (ItemId is used instead).
+    Guid? PurchaseOrderItemId,
+    int AcceptedQuantity,
+    int RejectedQuantity,
+    // Populated only when the item has TracksBatches and/or TracksExpiryDate set.
+    List<GrnBatchLineRequest>? Batches = null,
+    // Populated only when the item has TracksSerialNumbers set — must contain exactly AcceptedQuantity entries.
+    List<string>? SerialNumbers = null,
+    // Set for a direct receipt line (no purchase order).
+    Guid? ItemId = null);
 
 public record CreateGrnRequest(
     Guid WarehouseId,
@@ -15,21 +28,35 @@ public record CreateFlatGrnRequest(
     // TEMPORARY: required while auth doesn't resolve a logged-in user server-side — see testbug.md #28.
     Guid? ReceivedByUserId = null);
 
+/// <summary>A goods receipt with no purchase order. SupplierId is optional.</summary>
+public record CreateDirectGrnRequest(
+    Guid WarehouseId,
+    List<GrnItemRequest> Items,
+    Guid? SupplierId = null,
+    // TEMPORARY: required while auth doesn't resolve a logged-in user server-side — see testbug.md #28.
+    Guid? ReceivedByUserId = null);
+
+public record GrnBatchLineResponse(string? BatchNumber, DateTime? ExpiryDate, int Quantity);
+
 public record GrnItemResponse(
     Guid Id,
-    Guid PurchaseOrderItemId,
+    Guid? PurchaseOrderItemId,
     Guid ItemId,
     string Sku,
     string ItemName,
     int AcceptedQuantity,
-    int RejectedQuantity);
+    int RejectedQuantity,
+    List<GrnBatchLineResponse> Batches,
+    List<string> SerialNumbers);
 
 public record GrnResponse(
     Guid Id,
-    Guid PurchaseOrderId,
+    Guid? PurchaseOrderId,
     Guid ReceivedByUserId,
     Guid WarehouseId,
     string WarehouseName,
+    Guid? SupplierId,
+    string? SupplierName,
     DateTime ReceivedAt,
     DateTime CreatedAt,
     List<GrnItemResponse> Items);

Distribution/Features/Grn/GrnRepository.cs

@@ -8,13 +8,21 @@ public class GrnRepository(AppDBContext context) : IGrnRepository
     public async Task<Models.GoodsReceipt?> GetByIdAsync(Guid id) =>
         await context.GoodsReceipts
             .Include(gr => gr.Warehouse)
-            .Include(gr => gr.Items).ThenInclude(i => i.PurchaseOrderItem).ThenInclude(poi => poi.Item)
+            .Include(gr => gr.Supplier)
+            .Include(gr => gr.Items).ThenInclude(i => i.Item)
+            .Include(gr => gr.Items).ThenInclude(i => i.PurchaseOrderItem).ThenInclude(poi => poi!.Item)
+            .Include(gr => gr.Items).ThenInclude(i => i.Batches).ThenInclude(b => b.ItemBatch)
+            .Include(gr => gr.Items).ThenInclude(i => i.Serials).ThenInclude(s => s.ItemSerialNumber)
             .FirstOrDefaultAsync(gr => gr.Id == id);
 
     public async Task<List<Models.GoodsReceipt>> GetAllAsync(Guid? purchaseOrderId, int page, int pageSize) =>
         await context.GoodsReceipts
             .Include(gr => gr.Warehouse)
-            .Include(gr => gr.Items).ThenInclude(i => i.PurchaseOrderItem).ThenInclude(poi => poi.Item)
+            .Include(gr => gr.Supplier)
+            .Include(gr => gr.Items).ThenInclude(i => i.Item)
+            .Include(gr => gr.Items).ThenInclude(i => i.PurchaseOrderItem).ThenInclude(poi => poi!.Item)
+            .Include(gr => gr.Items).ThenInclude(i => i.Batches).ThenInclude(b => b.ItemBatch)
+            .Include(gr => gr.Items).ThenInclude(i => i.Serials).ThenInclude(s => s.ItemSerialNumber)
             .Where(gr => gr.IsActive && (purchaseOrderId == null || gr.FK_PurchaseOrderId == purchaseOrderId))
             .OrderByDescending(gr => gr.ReceivedAt)
             .Skip((page - 1) * pageSize)
@@ -29,7 +37,11 @@ public class GrnRepository(AppDBContext context) : IGrnRepository
     public async Task<List<Models.GoodsReceipt>> GetByPurchaseOrderIdAsync(Guid purchaseOrderId) =>
         await context.GoodsReceipts
             .Include(gr => gr.Warehouse)
-            .Include(gr => gr.Items).ThenInclude(i => i.PurchaseOrderItem).ThenInclude(poi => poi.Item)
+            .Include(gr => gr.Supplier)
+            .Include(gr => gr.Items).ThenInclude(i => i.Item)
+            .Include(gr => gr.Items).ThenInclude(i => i.PurchaseOrderItem).ThenInclude(poi => poi!.Item)
+            .Include(gr => gr.Items).ThenInclude(i => i.Batches).ThenInclude(b => b.ItemBatch)
+            .Include(gr => gr.Items).ThenInclude(i => i.Serials).ThenInclude(s => s.ItemSerialNumber)
             .Where(gr => gr.FK_PurchaseOrderId == purchaseOrderId && gr.IsActive)
             .OrderByDescending(gr => gr.ReceivedAt)
             .ToListAsync();
@@ -43,8 +55,8 @@ public class GrnRepository(AppDBContext context) : IGrnRepository
     public async Task<Dictionary<Guid, int>> GetAcceptedTotalsByItemAsync(Guid purchaseOrderId) =>
         await context.GoodsReceiptItems
             .Include(i => i.PurchaseOrderItem)
-            .Where(i => i.PurchaseOrderItem.FK_PurchaseOrderId == purchaseOrderId && i.IsActive)
+            .Where(i => i.PurchaseOrderItem!.FK_PurchaseOrderId == purchaseOrderId && i.IsActive)
-            .GroupBy(i => i.PurchaseOrderItem.FK_ItemId)
+            .GroupBy(i => i.PurchaseOrderItem!.FK_ItemId)
             .Select(g => new { ItemId = g.Key, Total = g.Sum(i => i.AcceptedQuantity) })
             .ToDictionaryAsync(x => x.ItemId, x => x.Total);
 }

Distribution/Features/Grn/GrnService.cs

@@ -9,14 +9,23 @@ public class GrnService(
     IGrnRepository repo,
     IPoRepository poRepo,
     IStockRepository stockRepo,
-    IUnitOfWork uow)
+    IUnitOfWork uow,
+    Distribution.Features.Item.IItemRepository itemRepo,
+    Distribution.Features.Supplier.ISupplierRepository supplierRepo)
 {
-    private static GrnItemResponse MapItem(Models.GoodsReceiptItem i) =>
+    private static GrnItemResponse MapItem(Models.GoodsReceiptItem i)
-        new(i.Id, i.FK_PurchaseOrderItemId, i.PurchaseOrderItem.FK_ItemId, i.PurchaseOrderItem.Item.Sku,
+    {
-            i.PurchaseOrderItem.Item.Name, i.AcceptedQuantity, i.RejectedQuantity);
+        // Direct-receipt lines carry the item themselves; PO lines resolve it through the PO line.
+        var item = i.Item ?? i.PurchaseOrderItem!.Item;
+        return new(i.Id, i.FK_PurchaseOrderItemId, item.Id, item.Sku, item.Name,
+            i.AcceptedQuantity, i.RejectedQuantity,
+            i.Batches.Select(b => new GrnBatchLineResponse(b.ItemBatch.BatchNumber, b.ItemBatch.ExpiryDate, b.Quantity)).ToList(),
+            i.Serials.Select(s => s.ItemSerialNumber.SerialNumber).ToList());
+    }
 
     private static GrnResponse Map(Models.GoodsReceipt gr) =>
         new(gr.Id, gr.FK_PurchaseOrderId, gr.FK_ReceivedByUserId, gr.FK_WarehouseId, gr.Warehouse?.Name ?? string.Empty,
+            gr.FK_SupplierId, gr.Supplier?.Name,
             gr.ReceivedAt, gr.CreatedAt, gr.Items.Where(i => i.IsActive).Select(MapItem).ToList());
 
     public async Task<PagedResponse<GrnResponse>> GetAllAsync(Guid? purchaseOrderId, int page, int pageSize)
@@ -36,10 +45,60 @@ public class GrnService(
     public async Task<List<GrnResponse>> GetByPurchaseOrderIdAsync(Guid purchaseOrderId) =>
         (await repo.GetByPurchaseOrderIdAsync(purchaseOrderId)).Select(Map).ToList();
 
+    /// <summary>
+    /// Validates that a GRN line's batch/serial payload matches the item's tracking flags. When an
+    /// item tracks both serial numbers and batches/expiry, serial tracking takes precedence for
+    /// stock-ledger granularity in this phase — batch/expiry metadata for that combination is not
+    /// yet linked into the ledger (follow-up work).
+    /// </summary>
+    private static void ValidateLineShape(Models.Item item, GrnItemRequest line)
+    {
+        if (item.TracksSerialNumbers)
+        {
+            if (line.AcceptedQuantity > 0 && (line.SerialNumbers is null || line.SerialNumbers.Count != line.AcceptedQuantity))
+                throw new InvalidOperationException(
+                    $"Item {item.Sku} tracks serial numbers — expected {line.AcceptedQuantity} serial number(s).");
+
+            if (line.SerialNumbers is { Count: > 0 } && line.SerialNumbers.Distinct().Count() != line.SerialNumbers.Count)
+                throw new InvalidOperationException($"Duplicate serial numbers supplied for item {item.Sku}.");
+        }
+        else if (line.SerialNumbers is { Count: > 0 })
+        {
+            throw new InvalidOperationException($"Item {item.Sku} does not track serial numbers.");
+        }
+        else if (item.TracksBatches || item.TracksExpiryDate)
+        {
+            if (line.AcceptedQuantity > 0)
+            {
+                if (line.Batches is null || line.Batches.Count == 0)
+                    throw new InvalidOperationException($"Item {item.Sku} requires batch/expiry information.");
+                if (line.Batches.Sum(b => b.Quantity) != line.AcceptedQuantity)
+                    throw new InvalidOperationException($"Batch quantities for item {item.Sku} must sum to the accepted quantity.");
+            }
+
+            foreach (var b in line.Batches ?? [])
+            {
+                if (b.Quantity <= 0)
+                    throw new InvalidOperationException($"Batch quantity for item {item.Sku} must be positive.");
+                if (item.TracksBatches && string.IsNullOrWhiteSpace(b.BatchNumber))
+                    throw new InvalidOperationException($"Item {item.Sku} requires a batch number.");
+                if (!item.TracksBatches && !string.IsNullOrWhiteSpace(b.BatchNumber))
+                    throw new InvalidOperationException($"Item {item.Sku} does not track batch numbers.");
+                if (item.TracksExpiryDate && b.ExpiryDate is null)
+                    throw new InvalidOperationException($"Item {item.Sku} requires an expiry date.");
+            }
+        }
+        else if (line.Batches is { Count: > 0 })
+        {
+            throw new InvalidOperationException($"Item {item.Sku} does not track batches or expiry dates.");
+        }
+    }
+
     /// <summary>
     /// Validates the Po status, increments PurchaseOrderItem.ReceivedQuantity, writes StockBalance/
-    /// StockMovement for AcceptedQuantity only (RejectedQuantity never touches stock), and
+    /// StockMovement for AcceptedQuantity only (RejectedQuantity never touches stock), creates
-    /// transitions the Po to PartiallyReceived/Received. All in one unit of work.
+    /// ItemBatch/ItemSerialNumber records for tracked items, and transitions the Po to
+    /// PartiallyReceived/Received. All in one unit of work.
     /// </summary>
     public async Task<GrnResponse> CreateAsync(Guid purchaseOrderId, CreateGrnRequest request, Guid receivedByUserId, CancellationToken ct = default)
     {
@@ -64,8 +123,13 @@ public class GrnService(
             ReceivedAt = DateTime.Now
         };
 
+        var grLines = new List<(Models.GoodsReceiptItem Entity, GrnItemRequest Line, Models.Item Item)>();
+
         foreach (var line in request.Items)
         {
+            if (line.PurchaseOrderItemId is null)
+                throw new InvalidOperationException("Each line of a PO receipt needs a PurchaseOrderItemId.");
+
             var poItem = po.Items.FirstOrDefault(i => i.Id == line.PurchaseOrderItemId && i.IsActive)
                 ?? throw new InvalidOperationException($"Purchase order line {line.PurchaseOrderItemId} not found on this Po.");
 
@@ -79,14 +143,27 @@ public class GrnService(
                 throw new InvalidOperationException(
                     $"Accepted + rejected quantity for item {poItem.FK_ItemId} would exceed the ordered quantity.");
 
+            ValidateLineShape(poItem.Item, line);
+
+            if (poItem.Item.TracksSerialNumbers && line.SerialNumbers is { Count: > 0 })
+            {
+                foreach (var serialNumber in line.SerialNumbers)
+                {
+                    if (await stockRepo.SerialNumberExistsAsync(poItem.FK_ItemId, serialNumber))
+                        throw new InvalidOperationException($"Serial number '{serialNumber}' already exists for item {poItem.Item.Sku}.");
+                }
+            }
+
             poItem.ReceivedQuantity += line.AcceptedQuantity;
 
-            goodsReceipt.Items.Add(new Models.GoodsReceiptItem
+            var entity = new Models.GoodsReceiptItem
             {
                 FK_PurchaseOrderItemId = poItem.Id,
                 AcceptedQuantity = line.AcceptedQuantity,
                 RejectedQuantity = line.RejectedQuantity
-            });
+            };
+            goodsReceipt.Items.Add(entity);
+            grLines.Add((entity, line, poItem.Item));
         }
 
         var activeLines = po.Items.Where(i => i.IsActive && !i.IsCancelled).ToList();
@@ -94,22 +171,203 @@ public class GrnService(
             ? PurchaseOrderStatus.Received
             : PurchaseOrderStatus.PartiallyReceived;
 
+        return await PostReceiptAsync(goodsReceipt, grLines, request.WarehouseId, receivedByUserId, po, ct);
+    }
+    /// <summary>
+    /// A receipt with no purchase order: lines name the item directly. Stock, serial and batch
+    /// handling is identical to a PO receipt; there is no PO quantity or status to update.
+    /// </summary>
+    public async Task<GrnResponse> CreateDirectAsync(CreateDirectGrnRequest request, Guid receivedByUserId, CancellationToken ct = default)
+    {
+        if (request.Items is null || request.Items.Count == 0)
+            throw new InvalidOperationException("A goods receipt must have at least one line item.");
+
+        if (request.SupplierId is not null && await supplierRepo.GetByIdAsync(request.SupplierId.Value) is not { IsActive: true })
+            throw new InvalidOperationException("Supplier not found.");
+
+        var goodsReceipt = new Models.GoodsReceipt
+        {
+            FK_PurchaseOrderId = null,
+            FK_SupplierId = request.SupplierId,
+            FK_ReceivedByUserId = receivedByUserId,
+            FK_WarehouseId = request.WarehouseId,
+            ReceivedAt = DateTime.Now
+        };
+
+        var grLines = new List<(Models.GoodsReceiptItem Entity, GrnItemRequest Line, Models.Item Item)>();
+        var serialsInRequest = new HashSet<(Guid ItemId, string Serial)>();
+
+        foreach (var line in request.Items)
+        {
+            if (line.ItemId is null)
+                throw new InvalidOperationException("Each line of a direct receipt needs an ItemId.");
+
+            var item = await itemRepo.GetByIdAsync(line.ItemId.Value);
+            if (item is null || !item.IsActive)
+                throw new InvalidOperationException($"Item {line.ItemId} not found.");
+
+            if (line.AcceptedQuantity < 0 || line.RejectedQuantity < 0)
+                throw new InvalidOperationException("Accepted/rejected quantities cannot be negative.");
+
+            if (line.AcceptedQuantity + line.RejectedQuantity == 0)
+                throw new InvalidOperationException($"Line for item {item.Sku} has no quantity.");
+
+            ValidateLineShape(item, line);
+
+            if (item.TracksSerialNumbers && line.SerialNumbers is { Count: > 0 })
+            {
+                foreach (var serialNumber in line.SerialNumbers)
+                {
+                    if (!serialsInRequest.Add((item.Id, serialNumber)))
+                        throw new InvalidOperationException($"Serial number '{serialNumber}' appears on more than one line for item {item.Sku}.");
+                    if (await stockRepo.SerialNumberExistsAsync(item.Id, serialNumber))
+                        throw new InvalidOperationException($"Serial number '{serialNumber}' already exists for item {item.Sku}.");
+                }
+            }
+
+            var entity = new Models.GoodsReceiptItem
+            {
+                FK_ItemId = item.Id,
+                AcceptedQuantity = line.AcceptedQuantity,
+                RejectedQuantity = line.RejectedQuantity
+            };
+            goodsReceipt.Items.Add(entity);
+            grLines.Add((entity, line, item));
+        }
+
+        return await PostReceiptAsync(goodsReceipt, grLines, request.WarehouseId, receivedByUserId, null, ct);
+    }
+
+    /// <summary>
+    /// Writes the receipt, its serials/batches, the stock balances and movements, and (for a PO
+    /// receipt) the PO update in one unit of work. Shared by PO-based and direct receipts.
+    /// </summary>
+    private async Task<GrnResponse> PostReceiptAsync(
+        Models.GoodsReceipt goodsReceipt,
+        List<(Models.GoodsReceiptItem Entity, GrnItemRequest Line, Models.Item Item)> grLines,
+        Guid warehouseId,
+        Guid receivedByUserId,
+        Models.PurchaseOrder? po,
+        CancellationToken ct)
+    {
         await uow.BeginAsync(ct);
         try
         {
             await repo.AddAsync(goodsReceipt);
 
-            foreach (var line in goodsReceipt.Items.Where(i => i.AcceptedQuantity > 0))
+            foreach (var (entity, line, item) in grLines.Where(x => x.Line.AcceptedQuantity > 0))
             {
-                var poItem = po.Items.First(i => i.Id == line.FK_PurchaseOrderItemId);
+                if (item.TracksSerialNumbers)
+                {
+                    foreach (var serialNumber in line.SerialNumbers!)
+                    {
+                        var serial = new ItemSerialNumber
+                        {
+                            FK_ItemId = item.Id,
+                            SerialNumber = serialNumber,
+                            Status = SerialStatus.InStock,
+                            CurrentLocationId = warehouseId,
+                            CurrentLocationType = LocationType.Warehouse,
+                            ReceivedAt = goodsReceipt.ReceivedAt
+                        };
 
-                var balance = await stockRepo.GetBalanceAsync(poItem.FK_ItemId, request.WarehouseId);
+                        // Warranty is a customer-facing promise: the clock starts when the serial is sold,
+                        // not at receipt. Only snapshot the item's custom period here; WarrantyExpiresAt
+                        // stays null until the sale/delivery flow sets it.
+                        if (item.HasWarranty && item.AllowCustomWarrantyPeriod)
+                            serial.WarrantyPeriodDaysOverride = item.WarrantyPeriodDays;
+
+                        await stockRepo.AddItemSerialNumberAsync(serial);
+                        entity.Serials.Add(new GoodsReceiptItemSerial { FK_GoodsReceiptItemId = entity.Id, ItemSerialNumber = serial });
+
+                        await stockRepo.AddBalanceAsync(new StockBalance
+                        {
+                            FK_ItemId = item.Id,
+                            LocationId = warehouseId,
+                            LocationType = LocationType.Warehouse,
+                            FK_ItemSerialNumberId = serial.Id,
+                            Quantity = 1
+                        });
+
+                        await stockRepo.AddMovementAsync(new StockMovement
+                        {
+                            FK_ItemId = item.Id,
+                            FromLocationId = StockService.ExternalLocationId,
+                            FromLocationType = LocationType.External,
+                            ToLocationId = warehouseId,
+                            ToLocationType = LocationType.Warehouse,
+                            FK_ItemSerialNumberId = serial.Id,
+                            Quantity = 1,
+                            Type = MovementType.PurchaseReceipt,
+                            ReferenceId = goodsReceipt.Id,
+                            CreatedBy = receivedByUserId
+                        });
+                    }
+                }
+                else if (item.TracksBatches || item.TracksExpiryDate)
+                {
+                    foreach (var b in line.Batches!)
+                    {
+                        var batch = !string.IsNullOrWhiteSpace(b.BatchNumber)
+                            ? await stockRepo.FindBatchAsync(item.Id, b.BatchNumber)
+                            : null;
+
+                        if (batch is null)
+                        {
+                            batch = new ItemBatch
+                            {
+                                FK_ItemId = item.Id,
+                                BatchNumber = b.BatchNumber,
+                                ExpiryDate = b.ExpiryDate
+                            };
+                            await stockRepo.AddItemBatchAsync(batch);
+                        }
+
+                        entity.Batches.Add(new GoodsReceiptItemBatch { FK_GoodsReceiptItemId = entity.Id, ItemBatch = batch, Quantity = b.Quantity });
+
+                        var balance = await stockRepo.GetBalanceAsync(item.Id, warehouseId, batch.Id, null);
                         if (balance is null)
                         {
                             await stockRepo.AddBalanceAsync(new StockBalance
                             {
-                        FK_ItemId = poItem.FK_ItemId,
+                                FK_ItemId = item.Id,
-                        LocationId = request.WarehouseId,
+                                LocationId = warehouseId,
+                                LocationType = LocationType.Warehouse,
+                                FK_ItemBatchId = batch.Id,
+                                Quantity = b.Quantity
+                            });
+                        }
+                        else
+                        {
+                            balance.Quantity += b.Quantity;
+                            balance.UpdatedAt = DateTime.Now;
+                            stockRepo.UpdateBalance(balance);
+                        }
+
+                        await stockRepo.AddMovementAsync(new StockMovement
+                        {
+                            FK_ItemId = item.Id,
+                            FromLocationId = StockService.ExternalLocationId,
+                            FromLocationType = LocationType.External,
+                            ToLocationId = warehouseId,
+                            ToLocationType = LocationType.Warehouse,
+                            FK_ItemBatchId = batch.Id,
+                            Quantity = b.Quantity,
+                            Type = MovementType.PurchaseReceipt,
+                            ReferenceId = goodsReceipt.Id,
+                            CreatedBy = receivedByUserId
+                        });
+                    }
+                }
+                else
+                {
+                    var balance = await stockRepo.GetBalanceAsync(item.Id, warehouseId);
+                    if (balance is null)
+                    {
+                        await stockRepo.AddBalanceAsync(new StockBalance
+                        {
+                            FK_ItemId = item.Id,
+                            LocationId = warehouseId,
                             LocationType = LocationType.Warehouse,
                             Quantity = line.AcceptedQuantity
                         });
@@ -123,10 +381,10 @@ public class GrnService(
 
                     await stockRepo.AddMovementAsync(new StockMovement
                     {
-                    FK_ItemId = poItem.FK_ItemId,
+                        FK_ItemId = item.Id,
                         FromLocationId = StockService.ExternalLocationId,
                         FromLocationType = LocationType.External,
-                    ToLocationId = request.WarehouseId,
+                        ToLocationId = warehouseId,
                         ToLocationType = LocationType.Warehouse,
                         Quantity = line.AcceptedQuantity,
                         Type = MovementType.PurchaseReceipt,
@@ -134,8 +392,9 @@ public class GrnService(
                         CreatedBy = receivedByUserId
                     });
                 }
+            }
 
-            poRepo.Update(po);
+            if (po is not null) poRepo.Update(po);
             await uow.CommitAsync(ct);
         }
         catch { await uow.RollbackAsync(ct); throw; }

Distribution/Models/GoodsReceipt.cs

@@ -4,9 +4,15 @@ namespace Distribution.Models
 {
     public class GoodsReceipt : Template
     {
-        public Guid FK_PurchaseOrderId { get; set; }
+        /// <summary>Null for a direct receipt (goods received without a purchase order).</summary>
+        public Guid? FK_PurchaseOrderId { get; set; }
         [ForeignKey("FK_PurchaseOrderId")]
-        public PurchaseOrder PurchaseOrder { get; set; }
+        public PurchaseOrder? PurchaseOrder { get; set; }
+
+        /// <summary>Optional supplier for a direct receipt; for PO receipts the supplier comes from the PO.</summary>
+        public Guid? FK_SupplierId { get; set; }
+        [ForeignKey("FK_SupplierId")]
+        public Supplier? Supplier { get; set; }
 
         public Guid FK_ReceivedByUserId { get; set; }
 

Distribution/Models/GoodsReceiptItem.cs

@@ -8,14 +8,26 @@ namespace Distribution.Models
         [ForeignKey("FK_GoodsReceiptId")]
         public GoodsReceipt GoodsReceipt { get; set; }
 
-        public Guid FK_PurchaseOrderItemId { get; set; }
+        /// <summary>Null for a direct receipt line (no purchase order); FK_ItemId is set instead.</summary>
+        public Guid? FK_PurchaseOrderItemId { get; set; }
         [ForeignKey("FK_PurchaseOrderItemId")]
-        public PurchaseOrderItem PurchaseOrderItem { get; set; }
+        public PurchaseOrderItem? PurchaseOrderItem { get; set; }
+
+        /// <summary>Set for direct receipt lines. PO-based lines resolve the item through PurchaseOrderItem.</summary>
+        public Guid? FK_ItemId { get; set; }
+        [ForeignKey("FK_ItemId")]
+        public Item? Item { get; set; }
 
         /// <summary>Added to warehouse stock.</summary>
         public int AcceptedQuantity { get; set; }
 
         /// <summary>Damaged/short at receipt, not added to stock.</summary>
         public int RejectedQuantity { get; set; } = 0;
+
+        /// <summary>Populated when the received item tracks batches and/or expiry dates.</summary>
+        public ICollection<GoodsReceiptItemBatch> Batches { get; set; } = [];
+
+        /// <summary>Populated when the received item tracks serial numbers.</summary>
+        public ICollection<GoodsReceiptItemSerial> Serials { get; set; } = [];
     }
 }

Distribution/Models/GoodsReceiptItemBatch.cs

@@ -0,0 +1,18 @@
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Distribution.Models
+{
+    /// <summary>One row per batch/expiry-lot split within a single GRN line.</summary>
+    public class GoodsReceiptItemBatch : Template
+    {
+        public Guid FK_GoodsReceiptItemId { get; set; }
+        [ForeignKey("FK_GoodsReceiptItemId")]
+        public GoodsReceiptItem GoodsReceiptItem { get; set; }
+
+        public Guid FK_ItemBatchId { get; set; }
+        [ForeignKey("FK_ItemBatchId")]
+        public ItemBatch ItemBatch { get; set; }
+
+        public int Quantity { get; set; }
+    }
+}

Distribution/Models/GoodsReceiptItemSerial.cs

@@ -0,0 +1,16 @@
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Distribution.Models
+{
+    /// <summary>One row per serial number received within a single GRN line.</summary>
+    public class GoodsReceiptItemSerial : Template
+    {
+        public Guid FK_GoodsReceiptItemId { get; set; }
+        [ForeignKey("FK_GoodsReceiptItemId")]
+        public GoodsReceiptItem GoodsReceiptItem { get; set; }
+
+        public Guid FK_ItemSerialNumberId { get; set; }
+        [ForeignKey("FK_ItemSerialNumberId")]
+        public ItemSerialNumber ItemSerialNumber { get; set; }
+    }
+}