Distribution/Features/Grn/GrnController.cs

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+using Distribution.Infra.Authorization;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Distribution.Features.Grn;
+
+[ApiController]
+[Authorize]
+public class GrnController(GrnService service, ICurrentUserService currentUser) : ControllerBase
+{
+    [HttpGet("api/goods-receipts/{id:guid}")]
+    public async Task<IActionResult> GetById(Guid id)
+    {
+        var result = await service.GetByIdAsync(id);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpGet("api/purchase-orders/{id:guid}/goods-receipts")]
+    public async Task<IActionResult> GetByPurchaseOrder(Guid id) =>
+        Ok(await service.GetByPurchaseOrderIdAsync(id));
+
+    [HttpPost("api/purchase-orders/{id:guid}/goods-receipts")]
+    public async Task<IActionResult> Create(Guid id, CreateGrnRequest request, CancellationToken ct)
+    {
+        var userId = currentUser.UserId ?? throw new UnauthorizedAccessException();
+        try
+        {
+            var result = await service.CreateAsync(id, request, userId, ct);
+            return CreatedAtAction(nameof(GetById), new { id = result.Id }, result);
+        }
+        catch (InvalidOperationException ex) { return Conflict(new { error = ex.Message }); }
+    }
+}

Distribution/Features/Grn/GrnDTOs.cs

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+namespace Distribution.Features.Grn;
+
+public record GrnItemRequest(Guid PurchaseOrderItemId, int AcceptedQuantity, int RejectedQuantity);
+
+public record CreateGrnRequest(Guid WarehouseId, List<GrnItemRequest> Items);
+
+public record GrnItemResponse(
+    Guid Id,
+    Guid PurchaseOrderItemId,
+    Guid ItemId,
+    string Sku,
+    string ItemName,
+    int AcceptedQuantity,
+    int RejectedQuantity);
+
+public record GrnResponse(
+    Guid Id,
+    Guid PurchaseOrderId,
+    Guid ReceivedByUserId,
+    Guid WarehouseId,
+    string WarehouseName,
+    DateTime ReceivedAt,
+    DateTime CreatedAt,
+    List<GrnItemResponse> Items);

Distribution/Features/Grn/GrnRepository.cs

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+using Distribution.Data;
+using Microsoft.EntityFrameworkCore;
+
+namespace Distribution.Features.Grn;
+
+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)
+            .FirstOrDefaultAsync(gr => gr.Id == id);
+
+    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)
+            .Where(gr => gr.FK_PurchaseOrderId == purchaseOrderId && gr.IsActive)
+            .OrderByDescending(gr => gr.ReceivedAt)
+            .ToListAsync();
+
+    public async Task AddAsync(Models.GoodsReceipt entity) =>
+        await context.GoodsReceipts.AddAsync(entity);
+
+    public async Task<bool> HasAnyForPurchaseOrderAsync(Guid purchaseOrderId) =>
+        await context.GoodsReceipts.AnyAsync(gr => gr.FK_PurchaseOrderId == purchaseOrderId && gr.IsActive);
+
+    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)
+            .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

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+using Distribution.Features.Po;
+using Distribution.Features.Stock;
+using Distribution.Infra.UoW;
+using Distribution.Models;
+
+namespace Distribution.Features.Grn;
+
+public class GrnService(
+    IGrnRepository repo,
+    IPoRepository poRepo,
+    IStockRepository stockRepo,
+    IUnitOfWork uow)
+{
+    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);
+
+    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.ReceivedAt, gr.CreatedAt, gr.Items.Where(i => i.IsActive).Select(MapItem).ToList());
+
+    public async Task<GrnResponse?> GetByIdAsync(Guid id)
+    {
+        var gr = await repo.GetByIdAsync(id);
+        if (gr is null || !gr.IsActive) return null;
+        return Map(gr);
+    }
+
+    public async Task<List<GrnResponse>> GetByPurchaseOrderIdAsync(Guid purchaseOrderId) =>
+        (await repo.GetByPurchaseOrderIdAsync(purchaseOrderId)).Select(Map).ToList();
+
+    /// <summary>
+    /// Validates the Po status, increments PurchaseOrderItem.ReceivedQuantity, writes StockBalance/
+    /// StockMovement for AcceptedQuantity only (RejectedQuantity never touches stock), 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)
+    {
+        var po = await poRepo.GetByIdAsync(purchaseOrderId)
+            ?? throw new InvalidOperationException("Purchase order not found.");
+
+        if (!po.IsActive)
+            throw new InvalidOperationException("Purchase order not found.");
+
+        if (po.Status is not (PurchaseOrderStatus.Issued or PurchaseOrderStatus.PartiallyReceived))
+            throw new InvalidOperationException(
+                $"Cannot receive goods against a purchase order in {po.Status} status.");
+
+        if (request.Items is null || request.Items.Count == 0)
+            throw new InvalidOperationException("A goods receipt must have at least one line item.");
+
+        var goodsReceipt = new Models.GoodsReceipt
+        {
+            FK_PurchaseOrderId = po.Id,
+            FK_ReceivedByUserId = receivedByUserId,
+            FK_WarehouseId = request.WarehouseId,
+            ReceivedAt = DateTime.Now
+        };
+
+        foreach (var line in request.Items)
+        {
+            var poItem = po.Items.FirstOrDefault(i => i.Id == line.PurchaseOrderItemId && i.IsActive)
+                ?? throw new InvalidOperationException($"Purchase order line {line.PurchaseOrderItemId} not found on this Po.");
+
+            if (poItem.IsCancelled)
+                throw new InvalidOperationException($"Line for item {poItem.FK_ItemId} is cancelled and cannot receive stock.");
+
+            if (line.AcceptedQuantity < 0 || line.RejectedQuantity < 0)
+                throw new InvalidOperationException("Accepted/rejected quantities cannot be negative.");
+
+            if (line.AcceptedQuantity + line.RejectedQuantity + poItem.ReceivedQuantity > poItem.Quantity)
+                throw new InvalidOperationException(
+                    $"Accepted + rejected quantity for item {poItem.FK_ItemId} would exceed the ordered quantity.");
+
+            poItem.ReceivedQuantity += line.AcceptedQuantity;
+
+            goodsReceipt.Items.Add(new Models.GoodsReceiptItem
+            {
+                FK_PurchaseOrderItemId = poItem.Id,
+                AcceptedQuantity = line.AcceptedQuantity,
+                RejectedQuantity = line.RejectedQuantity
+            });
+        }
+
+        var activeLines = po.Items.Where(i => i.IsActive && !i.IsCancelled).ToList();
+        po.Status = activeLines.Count > 0 && activeLines.All(i => i.ReceivedQuantity >= i.Quantity)
+            ? PurchaseOrderStatus.Received
+            : PurchaseOrderStatus.PartiallyReceived;
+
+        await uow.BeginAsync(ct);
+        try
+        {
+            await repo.AddAsync(goodsReceipt);
+
+            foreach (var line in goodsReceipt.Items.Where(i => i.AcceptedQuantity > 0))
+            {
+                var poItem = po.Items.First(i => i.Id == line.FK_PurchaseOrderItemId);
+
+                var balance = await stockRepo.GetBalanceAsync(poItem.FK_ItemId, request.WarehouseId);
+                if (balance is null)
+                {
+                    await stockRepo.AddBalanceAsync(new StockBalance
+                    {
+                        FK_ItemId = poItem.FK_ItemId,
+                        LocationId = request.WarehouseId,
+                        LocationType = LocationType.Warehouse,
+                        Quantity = line.AcceptedQuantity
+                    });
+                }
+                else
+                {
+                    balance.Quantity += line.AcceptedQuantity;
+                    balance.UpdatedAt = DateTime.Now;
+                    stockRepo.UpdateBalance(balance);
+                }
+
+                await stockRepo.AddMovementAsync(new StockMovement
+                {
+                    FK_ItemId = poItem.FK_ItemId,
+                    ToLocationId = request.WarehouseId,
+                    ToLocationType = LocationType.Warehouse,
+                    Quantity = line.AcceptedQuantity,
+                    Type = MovementType.PurchaseReceipt,
+                    ReferenceId = goodsReceipt.Id,
+                    CreatedBy = receivedByUserId
+                });
+            }
+
+            poRepo.Update(po);
+            await uow.CommitAsync(ct);
+        }
+        catch { await uow.RollbackAsync(ct); throw; }
+
+        var saved = await repo.GetByIdAsync(goodsReceipt.Id);
+        return Map(saved!);
+    }
+}

Distribution/Features/Grn/IGrnRepository.cs

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+namespace Distribution.Features.Grn;
+
+public interface IGrnRepository
+{
+    Task<Models.GoodsReceipt?> GetByIdAsync(Guid id);
+    Task<List<Models.GoodsReceipt>> GetByPurchaseOrderIdAsync(Guid purchaseOrderId);
+    Task AddAsync(Models.GoodsReceipt entity);
+
+    /// <summary>True if at least one GoodsReceipt exists against this Po (createPurchaseReturn guard).</summary>
+    Task<bool> HasAnyForPurchaseOrderAsync(Guid purchaseOrderId);
+
+    /// <summary>Sum of AcceptedQuantity per ItemId across all receipts for a Po.</summary>
+    Task<Dictionary<Guid, int>> GetAcceptedTotalsByItemAsync(Guid purchaseOrderId);
+}