feat: add warranty tracking for items and GRN lines

- Enhanced ItemService to include warranty and warranty period months in item DTOs.
- Implemented validation for warranty periods in ItemService.
- Updated frontend item detail and new item pages to handle warranty selection and input.
- Added warranty number handling in GRN creation and detail pages.
- Introduced new GrnLineWarrantyNumber entity to capture warranty numbers for received items.
- Created Warranty enum and associated allowed months for warranty coverage.
- Updated validation logic for GRN lines to ensure warranty numbers are captured correctly.

Backend/ERPCore/Domain/Entities/GrnLine.cs

@@ -58,4 +58,11 @@ public class GrnLine
     public decimal LineTotal { get; set; }
 
     public HoldStatus HoldStatus { get; set; } = HoldStatus.Available;
+
+    /// <summary>
+    /// One row per received unit when <see cref="Item.Warranty"/> is
+    /// <see cref="Enums.Warranty.Warranty"/> — count must equal <see cref="Qty"/>.
+    /// Empty for a non-warranty item.
+    /// </summary>
+    public ICollection<GrnLineWarrantyNumber> WarrantyNumbers { get; set; } = new List<GrnLineWarrantyNumber>();
 }

Backend/ERPCore/Domain/Entities/GrnLineWarrantyNumber.cs

@@ -0,0 +1,20 @@
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// One warranty number captured against a single received unit of a warranty-tracked
+/// item (<see cref="Item.Warranty"/> = <see cref="Enums.Warranty.Warranty"/>). A GRN line
+/// for such an item must carry exactly <see cref="GrnLine.Qty"/> of these — one per unit —
+/// mirroring how a Serial-tracked item requires one serial per unit (docs/10 Part C.3).
+/// </summary>
+public class GrnLineWarrantyNumber
+{
+    public int GrnLineWarrantyNumberId { get; set; }
+
+    public int GrnLineId { get; set; }
+    public GrnLine? GrnLine { get; set; }
+
+    public string WarrantyNo { get; set; } = string.Empty;
+
+    /// <summary>Warranty coverage length in months, selected at receipt (e.g. 3/6/12/18).</summary>
+    public int WarrantyPeriodMonths { get; set; }
+}

Backend/ERPCore/Domain/Entities/Item.cs

@@ -38,6 +38,9 @@ public class Item
 
     public StockNature StockNature { get; set; }
     public TrackingMode TrackingMode { get; set; }
+    public Warranty Warranty { get; set; } = Warranty.NonWarranty;
+    /// <summary>Coverage length in months (see <see cref="Enums.WarrantyPeriods.AllowedMonths"/>) when <see cref="Warranty"/> is Warranty; null otherwise.</summary>
+    public int? WarrantyPeriodMonths { get; set; }
     public string? TaxClass { get; set; }
 
     /// <summary>

Backend/ERPCore/Domain/Enums/Warranty.cs

@@ -0,0 +1,17 @@
+namespace ERPCore.Domain.Enums;
+
+/// <summary>
+/// Whether an item is sold under warranty (FR-MD-01). Stored as a string, same
+/// convention as <see cref="StockNature"/> and <see cref="TrackingMode"/>.
+/// </summary>
+public enum Warranty
+{
+    NonWarranty,
+    Warranty
+}
+
+/// <summary>Allowed warranty coverage lengths, in months — set once on the item (FR-MD-01).</summary>
+public static class WarrantyPeriods
+{
+    public static readonly int[] AllowedMonths = { 3, 6, 12, 18 };
+}

Backend/ERPCore/Dtos/Grn/GrnDtos.cs

@@ -5,12 +5,14 @@ namespace ERPCore.Dtos.Grn;
 
 // Responses (docs/11 §4) --------------------------------------------------------
 
+public sealed record GrnLineWarrantyNumberDto(string WarrantyNo, int WarrantyPeriodMonths);
+
 public sealed record GrnLineDto(
     int GrnLineId, int? PoLineId, int ItemId, int? BinId,
     decimal Qty, decimal UnitCost, decimal? PoUnitPrice,
     decimal DiscountPct, decimal NetUnitCost, decimal VatPct, decimal VatAmount,
     decimal ReceivedValue, decimal LineTotal, decimal PriceVariance,
-    HoldStatus HoldStatus, int? BatchId);
+    HoldStatus HoldStatus, int? BatchId, IReadOnlyList<GrnLineWarrantyNumberDto> WarrantyNumbers);
 
 public sealed record GrnDto(
     int GrnId, string DocNo, int? PoId, int VendorId, int WarehouseId, GrnStatus Status,
@@ -58,6 +60,11 @@ public sealed class CreateGrnLineInput
     [Range(0, 100)] public decimal VatPct { get; set; }
     [EnumDataType(typeof(HoldStatus))] public HoldStatus HoldStatus { get; set; } = HoldStatus.Available;
     public BatchInput? Batch { get; set; }
+    /// <summary>
+    /// Required, one per unit (count must equal <see cref="Qty"/>), when the item is
+    /// warranty-tracked (<c>Item.Warranty == Warranty.Warranty</c>). Ignored otherwise.
+    /// </summary>
+    public List<string>? WarrantyNumbers { get; set; }
 }
 
 public sealed class CreateGrnRequest

Backend/ERPCore/Dtos/Items/ItemDtos.cs

@@ -9,6 +9,7 @@ namespace ERPCore.Dtos.Items;
 public sealed record ItemListItemDto(
     int ItemId, string Sku, string Name, int CategoryId, int? SubCategoryId, int? BrandId,
     int BaseUomId, int? DefaultVendorId, StockNature StockNature, TrackingMode TrackingMode,
+    Warranty Warranty, int? WarrantyPeriodMonths,
     string? TaxClass, decimal? SalePrice,
     decimal? ContentQty, MeasureUnit? ContentUnit,
     decimal? ContentBaseQty, MeasureUnit? ContentBaseUnit,
@@ -29,6 +30,7 @@ public sealed record ItemDetailDto(
     int ItemId, string Sku, string Name, string? Description, int CategoryId,
     int? SubCategoryId, int? BrandId, int BaseUomId, int? DefaultVendorId,
     StockNature StockNature, TrackingMode TrackingMode,
+    Warranty Warranty, int? WarrantyPeriodMonths,
     string? TaxClass, decimal? SalePrice,
     decimal? ContentQty, MeasureUnit? ContentUnit,
     decimal? ContentBaseQty, MeasureUnit? ContentBaseUnit,
@@ -59,6 +61,9 @@ public sealed class CreateItemRequest
     public int? DefaultVendorId { get; set; }
     [Required, EnumDataType(typeof(StockNature))] public StockNature StockNature { get; set; }
     [EnumDataType(typeof(TrackingMode))] public TrackingMode TrackingMode { get; set; } = TrackingMode.None;
+    [EnumDataType(typeof(Warranty))] public Warranty Warranty { get; set; } = Warranty.NonWarranty;
+    /// <summary>Required (one of <see cref="Enums.WarrantyPeriods.AllowedMonths"/>) when <see cref="Warranty"/> is Warranty; ignored otherwise.</summary>
+    public int? WarrantyPeriodMonths { get; set; }
     [StringLength(20)] public string? TaxClass { get; set; }
     /// <summary>Optional fixed sale price (Sales only). Null ⇒ sell at stock/FIFO value.</summary>
     [Range(0, double.MaxValue)] public decimal? SalePrice { get; set; }
@@ -86,6 +91,9 @@ public sealed class UpdateItemRequest
     public int? DefaultVendorId { get; set; }
     [Required, EnumDataType(typeof(StockNature))] public StockNature StockNature { get; set; }
     [EnumDataType(typeof(TrackingMode))] public TrackingMode TrackingMode { get; set; } = TrackingMode.None;
+    [EnumDataType(typeof(Warranty))] public Warranty Warranty { get; set; } = Warranty.NonWarranty;
+    /// <summary>Required (one of <see cref="Enums.WarrantyPeriods.AllowedMonths"/>) when <see cref="Warranty"/> is Warranty; ignored otherwise.</summary>
+    public int? WarrantyPeriodMonths { get; set; }
     [StringLength(20)] public string? TaxClass { get; set; }
     /// <summary>Optional fixed sale price (Sales only). Null ⇒ sell at stock/FIFO value.</summary>
     [Range(0, double.MaxValue)] public decimal? SalePrice { get; set; }

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

@@ -53,3 +53,21 @@ public sealed class GrnLineConfiguration : IEntityTypeConfiguration<GrnLine>
         builder.HasOne(l => l.Batch).WithMany().HasForeignKey(l => l.BatchId).OnDelete(DeleteBehavior.Restrict);
     }
 }
+
+public sealed class GrnLineWarrantyNumberConfiguration : IEntityTypeConfiguration<GrnLineWarrantyNumber>
+{
+    public void Configure(EntityTypeBuilder<GrnLineWarrantyNumber> builder)
+    {
+        builder.ToTable("grn_line_warranty_numbers");
+        builder.HasKey(w => w.GrnLineWarrantyNumberId);
+
+        builder.Property(w => w.WarrantyNo).IsRequired().HasMaxLength(100);
+
+        builder.HasOne(w => w.GrnLine).WithMany(l => l.WarrantyNumbers)
+            .HasForeignKey(w => w.GrnLineId).OnDelete(DeleteBehavior.Cascade);
+
+        // A warranty number entered twice on the same line is almost certainly a typo —
+        // catch it at the DB, not just client-side.
+        builder.HasIndex(w => new { w.GrnLineId, w.WarrantyNo }).IsUnique();
+    }
+}

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

@@ -36,6 +36,9 @@ public sealed class ItemConfiguration : IEntityTypeConfiguration<Item>
             .HasConversion<string>().HasMaxLength(20).IsRequired();
         builder.Property(i => i.TrackingMode)
             .HasConversion<string>().HasMaxLength(20).IsRequired();
+        builder.Property(i => i.Warranty)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(Warranty.NonWarranty);
         builder.Property(i => i.Status)
             .HasConversion<string>().HasMaxLength(20).IsRequired()
             .HasDefaultValue(EntityStatus.Active);

Backend/ERPCore/Services/GrnService.cs

@@ -91,7 +91,7 @@ public sealed class GrnService : IGrnService
     public async Task<GrnDto?> GetAsync(int grnId, CancellationToken ct = default)
     {
         var grn = await _grns.Query().AsNoTracking()
-            .Include(g => g.Lines)
+            .Include(g => g.Lines).ThenInclude(l => l.WarrantyNumbers)
             .FirstOrDefaultAsync(g => g.GrnId == grnId, ct);
         return grn is null ? null : Map(grn);
     }
@@ -165,6 +165,7 @@ public sealed class GrnService : IGrnService
             var vatAmount = Math.Round(receivedValue * input.VatPct / 100m, 4, MidpointRounding.AwayFromZero);
 
             var batch = await ResolveBatchAsync(item, input.Batch, batchCache, ct);
+            var warrantyNumbers = ResolveWarrantyNumbers(item, input.WarrantyNumbers, input.Qty);
 
             lines.Add(new GrnLine
             {
@@ -181,7 +182,8 @@ public sealed class GrnService : IGrnService
                 VatAmount = vatAmount,
                 ReceivedValue = receivedValue,
                 LineTotal = receivedValue + vatAmount,
-                HoldStatus = input.HoldStatus
+                HoldStatus = input.HoldStatus,
+                WarrantyNumbers = warrantyNumbers
             });
         }
 
@@ -341,6 +343,30 @@ public sealed class GrnService : IGrnService
         return created; // linked via GrnLine.Batch navigation; FK fixed up on SaveChanges
     }
 
+    /// <summary>
+    /// A warranty-tracked item requires exactly one warranty number per received unit —
+    /// same shape of rule as <see cref="ResolveBatchAsync"/> for batch tracking. The coverage
+    /// period is not entered at receipt; it is snapshotted from <see cref="Item.WarrantyPeriodMonths"/>,
+    /// which the item must have been given at creation (<see cref="ItemService"/> enforces that).
+    /// </summary>
+    private static List<GrnLineWarrantyNumber> ResolveWarrantyNumbers(Item item, List<string>? numbers, decimal qty)
+    {
+        if (item.Warranty != Warranty.Warranty) return new List<GrnLineWarrantyNumber>();
+        if (item.WarrantyPeriodMonths is null)
+            throw new DomainException(
+                ErrorCodes.Validation, $"Item {item.Sku} is under warranty but has no warranty period configured.", 422);
+
+        var trimmed = (numbers ?? new List<string>()).Select(n => n.Trim()).Where(n => n.Length > 0).ToList();
+        if (trimmed.Count != qty)
+            throw new DomainException(
+                ErrorCodes.Validation,
+                $"Item {item.Sku} is under warranty; provide exactly {qty} warranty number(s), got {trimmed.Count}.", 422);
+        if (trimmed.Distinct(StringComparer.OrdinalIgnoreCase).Count() != trimmed.Count)
+            throw new DomainException(ErrorCodes.Validation, $"Warranty numbers for item {item.Sku} must be unique.", 422);
+
+        return trimmed.Select(n => new GrnLineWarrantyNumber { WarrantyNo = n, WarrantyPeriodMonths = item.WarrantyPeriodMonths.Value }).ToList();
+    }
+
     private async Task UpdatePoStatusAsync(int? poId, CancellationToken ct)
     {
         if (poId is null) return;
@@ -382,5 +408,6 @@ public sealed class GrnService : IGrnService
             l.GrnLineId, l.PoLineId, l.ItemId, l.BinId, l.Qty, l.UnitCost, l.PoUnitPrice,
             l.DiscountPct, l.NetUnitCost, l.VatPct, l.VatAmount, l.ReceivedValue, l.LineTotal,
             l.PoUnitPrice is null ? 0m : Math.Round((l.UnitCost - l.PoUnitPrice.Value) * l.Qty, 4, MidpointRounding.AwayFromZero),
-            l.HoldStatus, l.BatchId)).ToList());
+            l.HoldStatus, l.BatchId,
+            l.WarrantyNumbers.Select(w => new GrnLineWarrantyNumberDto(w.WarrantyNo, w.WarrantyPeriodMonths)).ToList())).ToList());
 }

Backend/ERPCore/Services/ItemService.cs

@@ -85,7 +85,7 @@ public sealed class ItemService : IItemService
             .Select(i => new ItemListItemDto(
                 i.ItemId, i.Sku, i.Name, i.CategoryId, i.SubCategoryId, i.BrandId,
                 i.BaseUomId, i.DefaultVendorId,
-                i.StockNature, i.TrackingMode, i.TaxClass, i.SalePrice,
+                i.StockNature, i.TrackingMode, i.Warranty, i.WarrantyPeriodMonths, i.TaxClass, i.SalePrice,
                 i.ContentQty, i.ContentUnit, i.ContentBaseQty, i.ContentBaseUnit,
                 i.Status))
             .ToListAsync(ct);
@@ -113,6 +113,7 @@ public sealed class ItemService : IItemService
 
         ItemContent.ValidatePair(request.ContentQty, request.ContentUnit);
         var (contentBaseQty, contentBaseUnit) = ItemContent.Normalize(request.ContentQty, request.ContentUnit);
+        var warrantyPeriodMonths = ValidateWarrantyPeriod(request.Warranty, request.WarrantyPeriodMonths);
 
         var item = new Item
         {
@@ -126,6 +127,8 @@ public sealed class ItemService : IItemService
             DefaultVendorId = request.DefaultVendorId,
             StockNature = request.StockNature,
             TrackingMode = request.TrackingMode,
+            Warranty = request.Warranty,
+            WarrantyPeriodMonths = warrantyPeriodMonths,
             TaxClass = request.TaxClass,
             SalePrice = request.SalePrice,
             ContentQty = request.ContentQty,
@@ -172,6 +175,7 @@ public sealed class ItemService : IItemService
 
         ItemContent.ValidatePair(request.ContentQty, request.ContentUnit);
         var (contentBaseQty, contentBaseUnit) = ItemContent.Normalize(request.ContentQty, request.ContentUnit);
+        var warrantyPeriodMonths = ValidateWarrantyPeriod(request.Warranty, request.WarrantyPeriodMonths);
 
         item.Sku = request.Sku.Trim();
         item.Name = request.Name.Trim();
@@ -183,6 +187,8 @@ public sealed class ItemService : IItemService
         item.DefaultVendorId = request.DefaultVendorId;
         item.StockNature = request.StockNature;
         item.TrackingMode = request.TrackingMode;
+        item.Warranty = request.Warranty;
+        item.WarrantyPeriodMonths = warrantyPeriodMonths;
         item.TaxClass = request.TaxClass;
         item.SalePrice = request.SalePrice;
         item.ContentQty = request.ContentQty;
@@ -326,6 +332,23 @@ public sealed class ItemService : IItemService
         }
     }
 
+    /// <summary>
+    /// A warranty-tracked item must declare a coverage period (one of
+    /// <see cref="WarrantyPeriods.AllowedMonths"/>); a non-warranty item carries none —
+    /// any value sent for one is silently dropped rather than trusted from the client.
+    /// </summary>
+    private static int? ValidateWarrantyPeriod(Warranty warranty, int? warrantyPeriodMonths)
+    {
+        if (warranty != Warranty.Warranty) return null;
+
+        if (warrantyPeriodMonths is null || !WarrantyPeriods.AllowedMonths.Contains(warrantyPeriodMonths.Value))
+            throw new DomainException(
+                ErrorCodes.Validation,
+                $"Warranty period must be one of {string.Join(", ", WarrantyPeriods.AllowedMonths)} months.", 422);
+
+        return warrantyPeriodMonths;
+    }
+
     private async Task SaveGuardingConcurrencyAsync(CancellationToken ct)
     {
         try
@@ -341,7 +364,7 @@ public sealed class ItemService : IItemService
     private static ItemDetailDto ToDetail(Item i) => new(
         i.ItemId, i.Sku, i.Name, i.Description, i.CategoryId, i.SubCategoryId, i.BrandId,
         i.BaseUomId, i.DefaultVendorId,
-        i.StockNature, i.TrackingMode, i.TaxClass, i.SalePrice,
+        i.StockNature, i.TrackingMode, i.Warranty, i.WarrantyPeriodMonths, i.TaxClass, i.SalePrice,
         i.ContentQty, i.ContentUnit, i.ContentBaseQty, i.ContentBaseUnit,
         i.Status,
         i.ReorderSettings

Frontend/erp-system/app/dashboard/products/[id]/page.tsx

@@ -12,7 +12,7 @@ import { warehousesApi } from "@/lib/api/warehouses"
 import { errorMessage, fieldErrors } from "@/lib/error-map"
 import { validateItemForm } from "@/lib/validations/master-data"
 import { cn } from "@/lib/utils"
-import { Item, MeasureUnit, StockNature, TrackingMode } from "@/types/master-data"
+import { Item, MeasureUnit, StockNature, TrackingMode, Warranty, WarrantyPeriodMonths } from "@/types/master-data"
 
 /** Entry units. Only ml/g are stored — the server normalises L and Kg ×1000 on write. */
 const CONTENT_UNITS: MeasureUnit[] = ["Ml", "L", "G", "Kg"]
@@ -54,6 +54,9 @@ export default function ItemDetailPage() {
   // carried through unchanged (from the loaded item) so a save doesn't silently clear them.
   const [defaultVendorId, setDefaultVendorId] = useState<number | null>(null)
   const [trackingMode, setTrackingMode] = useState<TrackingMode>("None")
+  // Not editable here — carried through unchanged so a save doesn't silently reset it.
+  const [warranty, setWarranty] = useState<Warranty>("NonWarranty")
+  const [warrantyPeriodMonths, setWarrantyPeriodMonths] = useState<WarrantyPeriodMonths | null>(null)
   const [taxClass, setTaxClass] = useState("")
   // Raw string: an empty box means "no content size", which is not the same as 0.
   const [contentQty, setContentQty] = useState("")
@@ -80,6 +83,8 @@ export default function ItemDetailPage() {
     setDefaultVendorId(data.defaultVendorId)
     setStockNature(data.stockNature)
     setTrackingMode(data.trackingMode)
+    setWarranty(data.warranty)
+    setWarrantyPeriodMonths(data.warrantyPeriodMonths)
     setTaxClass(data.taxClass ?? "")
     setContentQty(data.contentQty === null ? "" : String(data.contentQty))
     setContentUnit(data.contentUnit)
@@ -123,7 +128,7 @@ export default function ItemDetailPage() {
         item.itemId,
         {
           sku, name, description: description || null, categoryId: categoryId as number, subCategoryId, brandId,
-          baseUomId: baseUomId as number, defaultVendorId, stockNature, trackingMode,
+          baseUomId: baseUomId as number, defaultVendorId, stockNature, trackingMode, warranty, warrantyPeriodMonths,
           taxClass: taxClass || null,
           contentQty: contentQty.trim() ? Number(contentQty) : null,
           contentUnit: contentQty.trim() ? contentUnit : null,

Frontend/erp-system/app/dashboard/products/new/page.tsx

@@ -20,7 +20,18 @@ import {
   validateVariantPrices,
 } from "@/lib/validations/master-data"
 import { cn } from "@/lib/utils"
-import { Brand, Category, ItemType, MeasureUnit, ProductConfig, StockNature, SubCategory } from "@/types/master-data"
+import {
+  Brand,
+  Category,
+  ItemType,
+  MeasureUnit,
+  ProductConfig,
+  StockNature,
+  SubCategory,
+  WARRANTY_PERIOD_MONTHS_OPTIONS,
+  Warranty,
+  WarrantyPeriodMonths,
+} from "@/types/master-data"
 
 /** Entry units. Only ml/g are stored — the server normalises L and Kg ×1000 on write. */
 const CONTENT_UNITS: MeasureUnit[] = ["Ml", "L", "G", "Kg"]
@@ -125,6 +136,10 @@ export default function NewItemPage() {
   const [pricesByKey, setPricesByKey] = useState<Record<string, string>>({})
   const [priceErrors, setPriceErrors] = useState<Record<string, string>>({})
 
+  // Warranty (FR-MD-01). Applies to every generated variant — there is no per-variant override.
+  const [warranty, setWarranty] = useState<Warranty>("NonWarranty")
+  const [warrantyPeriodMonths, setWarrantyPeriodMonths] = useState<WarrantyPeriodMonths | null>(null)
+
   const [errors, setErrors] = useState<Record<string, string>>({})
   const [submitError, setSubmitError] = useState<string | null>(null)
   const [submitting, setSubmitting] = useState(false)
@@ -340,6 +355,9 @@ export default function NewItemPage() {
     if (measurableCheckedCount > 1) {
       nextErrors.measurable = "Only one measurement dimension can be used at a time."
     }
+    if (warranty === "Warranty" && warrantyPeriodMonths === null) {
+      nextErrors.warrantyPeriodMonths = "Select a warranty period"
+    }
     // Should never fire — addValue is the real gate — so it catches stale state only.
     const contentSweep = validateVariantContent(
       variants.map((v) => v.key),
@@ -381,6 +399,8 @@ export default function NewItemPage() {
           baseUomId,
           stockNature,
           trackingMode: "None",
+          warranty,
+          warrantyPeriodMonths: warranty === "Warranty" ? warrantyPeriodMonths : null,
           salePrice: priceMode === "fixed" ? Number(priceFor(variant.key)) : null,
           // Each variant carries its OWN size when a measurement dimension supplied one;
           // otherwise the shared form-level pair, which is correct when the varying dimension
@@ -672,6 +692,64 @@ export default function NewItemPage() {
             )}
           </div>
 
+          {/* Warranty (FR-MD-01). Frontend-only toggle, mirrors the Sale price bar above. */}
+          <div className="flex flex-col gap-4 rounded-xl border p-5">
+            <div>
+              <h2 className="text-lg font-semibold text-foreground">Warranty</h2>
+              <p className="text-sm text-muted-foreground">
+                Mark whether every generated variant is sold under warranty.
+              </p>
+            </div>
+
+            <div className="inline-flex w-fit rounded-lg border p-1">
+              <button
+                type="button"
+                onClick={() => {
+                  setWarranty("NonWarranty")
+                  setWarrantyPeriodMonths(null)
+                }}
+                className={cn(
+                  "rounded-md px-4 py-2 text-base font-medium transition-colors",
+                  warranty === "NonWarranty" ? "bg-primary text-primary-foreground" : "text-muted-foreground hover:bg-muted/50",
+                )}
+              >
+                Non-Warranty
+              </button>
+              <button
+                type="button"
+                onClick={() => setWarranty("Warranty")}
+                className={cn(
+                  "rounded-md px-4 py-2 text-base font-medium transition-colors",
+                  warranty === "Warranty" ? "bg-primary text-primary-foreground" : "text-muted-foreground hover:bg-muted/50",
+                )}
+              >
+                Warranty
+              </button>
+            </div>
+
+            {warranty === "Warranty" && (
+              <div className="flex flex-col gap-1.5">
+                <Label>Warranty period</Label>
+                <Select<WarrantyPeriodMonths>
+                  value={warrantyPeriodMonths}
+                  onValueChange={(v) => v && setWarrantyPeriodMonths(v)}
+                >
+                  <SelectTrigger className="h-11! w-48 text-base" aria-invalid={!!errors.warrantyPeriodMonths}>
+                    <SelectValue placeholder="Select period" />
+                  </SelectTrigger>
+                  <SelectContent>
+                    {WARRANTY_PERIOD_MONTHS_OPTIONS.map((months) => (
+                      <SelectItem key={months} value={months} className="text-base">
+                        {months} months
+                      </SelectItem>
+                    ))}
+                  </SelectContent>
+                </Select>
+                <FieldError errors={[errors.warrantyPeriodMonths ? { message: errors.warrantyPeriodMonths } : undefined]} />
+              </div>
+            )}
+          </div>
+
           {/* itemTypesEnabled is advisory — the server cannot enforce it (items hold no
               item-type reference), so this section IS the enforcement. */}
           {config?.itemTypesEnabled && (

Frontend/erp-system/app/dashboard/receiving/grn/[id]/page.tsx

@@ -15,6 +15,7 @@ import { cn } from "@/lib/utils"
 import { ConfirmGrnResponse, Grn } from "@/types/grn"
 import { Bin, ItemListItem, Uom } from "@/types/master-data"
 
+import { Badge } from "@/components/ui/badge"
 import { Button, buttonVariants } from "@/components/ui/button"
 import { Skeleton } from "@/components/ui/skeleton"
 import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
@@ -176,7 +177,20 @@ export default function GrnDetailPage() {
             const item = itemFor(line.itemId)
             return (
               <TableRow key={line.grnLineId}>
-                <TableCell className="px-3 py-3.5">{item ? `${item.sku} — ${item.name}` : `Item #${line.itemId}`}</TableCell>
+                <TableCell className="px-3 py-3.5">
+                  <div className="flex items-center gap-2">
+                    {item ? `${item.sku} — ${item.name}` : `Item #${line.itemId}`}
+                    {item?.warranty === "Warranty" && <Badge variant="outline" className="text-xs">Warranty</Badge>}
+                  </div>
+                  {line.warrantyNumbers.length > 0 && (
+                    <p
+                      className="mt-1 text-xs text-muted-foreground"
+                      title={line.warrantyNumbers.map((w) => `${w.warrantyNo} (${w.warrantyPeriodMonths}mo)`).join(", ")}
+                    >
+                      {line.warrantyNumbers.length} warranty number{line.warrantyNumbers.length === 1 ? "" : "s"} captured
+                    </p>
+                  )}
+                </TableCell>
                 <TableCell className="px-3 py-3.5">{baseUomLabel(items, uoms, line.itemId)}</TableCell>
                 <TableCell className="px-3 py-3.5">{binFor(line.binId)}</TableCell>
                 <TableCell className="px-3 py-3.5">{line.qty}</TableCell>

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

@@ -3,7 +3,7 @@
 import { useEffect, useState } from "react"
 import { useRouter } from "next/navigation"
 import Link from "next/link"
-import { ExternalLink, Plus, RefreshCw, Trash2 } from "lucide-react"
+import { ArrowLeft, ExternalLink, Plus, RefreshCw, ShieldCheck, Trash2 } from "lucide-react"
 
 import { grnsApi } from "@/lib/api/grns"
 import { purchaseOrdersApi } from "@/lib/api/purchase-orders"
@@ -13,12 +13,13 @@ import { itemsApi } from "@/lib/api/items"
 import { uomsApi } from "@/lib/api/uoms"
 import { baseUomLabel } from "@/lib/uom-label"
 import { errorMessage } from "@/lib/error-map"
-import { validateLine, splitSerials, grnHeaderSchema } from "@/lib/validations/grn"
+import { validateLine, grnHeaderSchema } from "@/lib/validations/grn"
 import { cn } from "@/lib/utils"
 import { CreateGrnLineInput, HoldStatus } from "@/types/grn"
 import { PurchaseOrder, PurchaseOrderSummary } from "@/types/procurement"
 import { Bin, ItemListItem, Uom, Vendor, Warehouse } from "@/types/master-data"
 
+import { Badge } from "@/components/ui/badge"
 import { Button, buttonVariants } from "@/components/ui/button"
 import { Input } from "@/components/ui/input"
 import { Label } from "@/components/ui/label"
@@ -27,8 +28,41 @@ import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@
 import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
 import { Skeleton } from "@/components/ui/skeleton"
 import { toast } from "@/components/ui/toast"
+import { Tooltip, TooltipContent, TooltipTrigger } from "@/components/ui/tooltip"
 
 type Mode = "po" | "direct"
+type LineTab = "lines" | "warranty"
+
+/** Whole units a line's qty represents — one warranty number is captured per unit. */
+function unitCount(qty: string): number {
+  const n = Math.floor(Number(qty))
+  return Number.isFinite(n) && n > 0 ? n : 0
+}
+
+/** One-shot hint next to the warranty button — shows on mount, then fades out on its own. */
+function WarrantyHintBubble() {
+  const [visible, setVisible] = useState(true)
+
+  useEffect(() => {
+    const timer = setTimeout(() => setVisible(false), 3000)
+    return () => clearTimeout(timer)
+  }, [])
+
+  return (
+    <div
+      role="status"
+      className={cn(
+        "absolute bottom-full right-0 z-10 mb-2 flex w-max max-w-xs items-center gap-2 rounded-xl border border-info/40 bg-white p-3 shadow-xl transition-opacity duration-700",
+        visible ? "opacity-100" : "pointer-events-none opacity-0"
+      )}
+    >
+      <span className="flex size-7 shrink-0 items-center justify-center rounded-full bg-info/15 text-info">
+        <ShieldCheck className="size-4" />
+      </span>
+      <span className="min-w-0 text-sm font-semibold text-info">Add warranty numbers for this item</span>
+    </div>
+  )
+}
 
 interface DraftLine {
   key: string
@@ -42,9 +76,8 @@ interface DraftLine {
   discountPct: string
   vatPct: string
   holdStatus: HoldStatus
-  batchNo: string
+  /** One entry per received unit, index-aligned; only meaningful when the item is warranty-tracked. */
-  expiryDate: string
+  warrantyNumbers: string[]
-  serialNumbersText: string
 }
 
 /** Mirror of the server's line arithmetic — display only (docs/20 §3, server stays authoritative). */
@@ -77,9 +110,7 @@ function emptyLine(): DraftLine {
     discountPct: "0",
     vatPct: "0",
     holdStatus: "Available",
-    batchNo: "",
+    warrantyNumbers: [],
-    expiryDate: "",
-    serialNumbersText: "",
   }
 }
 
@@ -101,6 +132,7 @@ export default function NewGrnPage() {
   const [poId, setPoId] = useState<number | null>(null)
   const [poLoading, setPoLoading] = useState(false)
   const [lines, setLines] = useState<DraftLine[]>([emptyLine()])
+  const [lineTab, setLineTab] = useState<LineTab>("lines")
 
   const [headerError, setHeaderError] = useState<string | null>(null)
   const [lineErrors, setLineErrors] = useState<Record<string, Record<string, string>>>({})
@@ -174,9 +206,7 @@ export default function NewGrnPage() {
             discountPct: "0",
             vatPct: "0",
             holdStatus: "Available",
-            batchNo: "",
+            warrantyNumbers: [],
-            expiryDate: "",
-            serialNumbersText: "",
           })
         )
       )
@@ -214,6 +244,24 @@ export default function NewGrnPage() {
     return items?.find((i) => i.itemId === itemId) ?? null
   }
 
+  function setWarrantyNumberAt(lineKey: string, index: number, value: string) {
+    setLines((prev) =>
+      prev.map((l) => {
+        if (l.key !== lineKey) return l
+        const next = [...l.warrantyNumbers]
+        while (next.length <= index) next.push("")
+        next[index] = value
+        return { ...l, warrantyNumbers: next }
+      })
+    )
+  }
+
+  // Lines whose item is warranty-tracked and carry at least one unit — these are the rows
+  // the "Warranty numbers" tab needs to capture, one input per unit.
+  const warrantyLines = lines
+    .map((l) => ({ line: l, item: itemFor(l.itemId), units: unitCount(l.qty) }))
+    .filter((w) => w.item?.warranty === "Warranty" && w.units > 0)
+
   async function handleSubmit() {
     setSubmitError(null)
     setHeaderError(null)
@@ -242,26 +290,31 @@ export default function NewGrnPage() {
 
     const nextLineErrors: Record<string, Record<string, string>> = {}
     for (const line of lines) {
+      const item = itemFor(line.itemId)
       const errors = validateLine({
         itemId: line.itemId,
         qty: line.qty,
         unitCost: line.unitCost,
         discountPct: line.discountPct,
         vatPct: line.vatPct,
-        trackingMode: itemFor(line.itemId)?.trackingMode ?? null,
+        warranty: item?.warranty ?? null,
-        batchNo: line.batchNo,
+        warrantyNumbers: line.warrantyNumbers,
-        serialNumbersText: line.serialNumbersText,
       })
       if (Object.keys(errors).length > 0) nextLineErrors[line.key] = errors
     }
     setLineErrors(nextLineErrors)
     if (Object.keys(nextLineErrors).length > 0) {
+      // Jump to whichever tab actually shows the offending field(s).
+      const onlyWarrantyErrors = Object.values(nextLineErrors).every(
+        (errs) => Object.keys(errs).every((k) => k === "warrantyNumbers")
+      )
+      setLineTab(onlyWarrantyErrors ? "warranty" : "lines")
       setSubmitError("Fix the highlighted lines before submitting.")
       return
     }
 
     const payloadLines: CreateGrnLineInput[] = lines.map((l) => {
-      const trackingMode = itemFor(l.itemId)?.trackingMode ?? "None"
+      const item = itemFor(l.itemId)
       return {
         poLineId: l.poLineId,
         itemId: l.itemId as number,
@@ -271,8 +324,10 @@ export default function NewGrnPage() {
         discountPct: Number(l.discountPct) || 0,
         vatPct: Number(l.vatPct) || 0,
         holdStatus: l.holdStatus,
-        batch: trackingMode === "Batch" ? { batchNo: l.batchNo.trim(), expiryDate: l.expiryDate || null } : null,
+        warrantyNumbers:
-        serialNumbers: trackingMode === "Serial" ? splitSerials(l.serialNumbersText) : null,
+          item?.warranty === "Warranty"
+            ? l.warrantyNumbers.map((s) => s.trim()).filter((s) => s.length > 0)
+            : null,
       }
     })
 
@@ -432,23 +487,49 @@ export default function NewGrnPage() {
               </div>
             </div>
 
+            <div className="flex w-fit gap-2 rounded-full border border-input bg-muted/40 p-1">
+              <Button
+                type="button"
+                size="sm"
+                variant={lineTab === "lines" ? "default" : "ghost"}
+                className="rounded-full"
+                onClick={() => setLineTab("lines")}
+              >
+                Lines
+              </Button>
+              <Button
+                type="button"
+                size="sm"
+                variant={lineTab === "warranty" ? "default" : "ghost"}
+                className="rounded-full"
+                onClick={() => setLineTab("warranty")}
+              >
+                Warranty numbers
+                {warrantyLines.length > 0 && (
+                  <Badge variant="outline" className="ml-1.5 h-5 px-1.5 text-xs">
+                    {warrantyLines.reduce((sum, w) => sum + w.units, 0)}
+                  </Badge>
+                )}
+              </Button>
+            </div>
+
             {poLoading && <Skeleton className="h-24 w-full" />}
 
-            {!poLoading && lines.length > 0 && (
+            {!poLoading && lineTab === "lines" && lines.length > 0 && (
               <div className="overflow-x-auto">
-                <Table className="text-base">
+                <Table className="text-sm">
                   <TableHeader>
                     <TableRow>
                       <TableHead className="h-12 w-56 px-3 text-sm">Item</TableHead>
                       <TableHead className="h-12 w-24 px-3 text-sm">UOM</TableHead>
                       <TableHead className="h-12 w-28 px-3 text-sm">Bin</TableHead>
-                      <TableHead className="h-12 w-32 px-3 text-sm">Qty</TableHead>
+                      <TableHead className="h-12 w-88 px-3 text-sm">Qty</TableHead>
-                      <TableHead className="h-12 w-28 px-3 text-sm">Unit cost</TableHead>
+                      <TableHead className="h-12 w-77 px-3 text-sm">Unit cost</TableHead>
-                      <TableHead className="h-12 w-24 px-3 text-sm">Disc %</TableHead>
+                      <TableHead className="h-12 w-44 px-3 text-sm">Disc %</TableHead>
-                      <TableHead className="h-12 w-24 px-3 text-sm">VAT %</TableHead>
+                      <TableHead className="h-12 w-44 px-3 text-sm">VAT %</TableHead>
                       <TableHead className="h-12 w-28 px-3 text-sm text-right">Line total</TableHead>
                       <TableHead className="h-12 w-56 px-3 text-sm">Hold status</TableHead>
-                      <TableHead className="h-12 w-44 px-3 text-sm">Batch / Serial</TableHead>
+                      <TableHead className="h-12 w-6 px-1 text-sm">Action</TableHead>
                       <TableHead className="h-12 w-10 px-3" />
                     </TableRow>
                   </TableHeader>
@@ -460,40 +541,47 @@ export default function NewGrnPage() {
                         <TableRow key={line.key}>
                           <TableCell className="px-3 py-3 align-top">
                             {line.poLineId ? (
-                              <div className="flex h-11 items-center text-base">
+                              <div className="flex h-11 items-center gap-2 text-sm">
                                 {item ? `${item.sku} — ${item.name}` : `Item #${line.itemId}`}
+                                {item?.warranty === "Warranty" && (
+                                  <Badge variant="outline" className="text-xs">Warranty</Badge>
+                                )}
                               </div>
                             ) : (
                               <>
                                 <Select<number | null> value={line.itemId} onValueChange={(v) => updateLine(line.key, { itemId: v })}>
-                                  <SelectTrigger className="h-11! w-full text-base" aria-invalid={!!errors.itemId}>
+                                  <SelectTrigger className="h-11! w-full text-sm" aria-invalid={!!errors.itemId}>
                                     <SelectValue placeholder="Select item" />
                                   </SelectTrigger>
                                   <SelectContent>
                                     {(items ?? []).map((i) => (
-                                      <SelectItem key={i.itemId} value={i.itemId} className="text-base">
+                                      <SelectItem key={i.itemId} value={i.itemId} className="text-sm">
                                         {i.sku} — {i.name}
+                                        {i.warranty === "Warranty" ? " (Warranty)" : ""}
                                       </SelectItem>
                                     ))}
                                   </SelectContent>
                                 </Select>
+                                {item?.warranty === "Warranty" && (
+                                  <Badge variant="outline" className="mt-1.5 text-xs">Warranty</Badge>
+                                )}
                                 <FieldError errors={[errors.itemId ? { message: errors.itemId } : undefined]} />
                               </>
                             )}
                           </TableCell>
                           <TableCell className="px-3 py-3 align-top">
-                            <div className="flex h-11 items-center text-base text-muted-foreground">
+                            <div className="flex h-11 items-center text-sm text-muted-foreground">
                               {baseUomLabel(items ?? [], uoms ?? [], line.itemId)}
                             </div>
                           </TableCell>
                           <TableCell className="px-3 py-3 align-top">
                             <Select<number | null> value={line.binId} onValueChange={(v) => updateLine(line.key, { binId: v })}>
-                              <SelectTrigger className="h-11! w-full text-base">
+                              <SelectTrigger className="h-11! w-full text-sm">
                                 <SelectValue placeholder="None" />
                               </SelectTrigger>
                               <SelectContent>
                                 {bins.map((b) => (
-                                  <SelectItem key={b.binId} value={b.binId} className="text-base">
+                                  <SelectItem key={b.binId} value={b.binId} className="text-sm">
                                     {b.code}
                                   </SelectItem>
                                 ))}
@@ -508,7 +596,7 @@ export default function NewGrnPage() {
                               value={line.qty}
                               aria-invalid={!!errors.qty}
                               onChange={(e) => updateLine(line.key, { qty: e.target.value })}
-                              className="h-11 text-base"
+                              className="h-11 text-sm"
                             />
                             <FieldError errors={[errors.qty ? { message: errors.qty } : undefined]} />
                           </TableCell>
@@ -520,7 +608,7 @@ export default function NewGrnPage() {
                               value={line.unitCost}
                               aria-invalid={!!errors.unitCost}
                               onChange={(e) => updateLine(line.key, { unitCost: e.target.value })}
-                              className="h-11 text-base"
+                              className="h-11 text-sm"
                             />
                             <FieldError errors={[errors.unitCost ? { message: errors.unitCost } : undefined]} />
                             {line.poUnitPrice !== null && Number(line.unitCost) !== line.poUnitPrice && (
@@ -538,7 +626,7 @@ export default function NewGrnPage() {
                               value={line.discountPct}
                               aria-invalid={!!errors.discountPct}
                               onChange={(e) => updateLine(line.key, { discountPct: e.target.value })}
-                              className="h-11 text-base"
+                              className="h-11 text-sm"
                             />
                             <FieldError errors={[errors.discountPct ? { message: errors.discountPct } : undefined]} />
                           </TableCell>
@@ -551,7 +639,7 @@ export default function NewGrnPage() {
                               value={line.vatPct}
                               aria-invalid={!!errors.vatPct}
                               onChange={(e) => updateLine(line.key, { vatPct: e.target.value })}
-                              className="h-11 text-base"
+                              className="h-11 text-sm"
                             />
                             <FieldError errors={[errors.vatPct ? { message: errors.vatPct } : undefined]} />
                           </TableCell>
@@ -573,51 +661,44 @@ export default function NewGrnPage() {
                               value={line.holdStatus}
                               onValueChange={(v) => v && updateLine(line.key, { holdStatus: v })}
                             >
-                              <SelectTrigger className="h-11! w-full text-base">
+                              <SelectTrigger className="h-11! w-full text-sm">
                                 <SelectValue />
                               </SelectTrigger>
                               <SelectContent>
-                                <SelectItem value="Available" className="text-base">Available</SelectItem>
+                                <SelectItem value="Available" className="text-sm">Available</SelectItem>
-                                <SelectItem value="OnHold" className="text-base">On hold (inspection)</SelectItem>
+                                <SelectItem value="OnHold" className="text-sm">On hold (inspection)</SelectItem>
                               </SelectContent>
                             </Select>
                           </TableCell>
-                          <TableCell className="px-3 py-3 align-top">
+                          <TableCell className="py-3 pr-0 pl-1 align-top">
-                            {item?.trackingMode === "Batch" && (
+                            {item?.warranty === "Warranty" ? (
-                              <div className="flex flex-col gap-1.5">
+                              <div className="relative flex flex-col gap-1">
-                                <Input
+                                <Tooltip>
-                                  placeholder="Batch no."
+                                  <TooltipTrigger
-                                  value={line.batchNo}
+                                    render={
-                                  aria-invalid={!!errors.batchNo}
+                                      <Button
-                                  onChange={(e) => updateLine(line.key, { batchNo: e.target.value })}
+                                        type="button"
-                                  className="h-9 text-sm"
+                                        variant="outline"
+                                        size="icon"
+                                        onClick={() => setLineTab("warranty")}
+                                        aria-label="Add warranty numbers"
                                       />
-                                <Input
+                                    }
-                                  type="date"
+                                  >
-                                  value={line.expiryDate}
+                                    <ShieldCheck className="size-4" />
-                                  onChange={(e) => updateLine(line.key, { expiryDate: e.target.value })}
+                                  </TooltipTrigger>
-                                  className="h-9 text-sm"
+                                  <TooltipContent>Add warranty numbers</TooltipContent>
-                                />
+                                </Tooltip>
-                                <FieldError errors={[errors.batchNo ? { message: errors.batchNo } : undefined]} />
+                                {errors.warrantyNumbers && (
-                              </div>
+                                  <FieldError errors={[{ message: errors.warrantyNumbers }]} />
                                 )}
-                            {item?.trackingMode === "Serial" && (
+                                <WarrantyHintBubble />
-                              <div className="flex flex-col gap-1.5">
-                                <textarea
-                                  placeholder="One serial per line"
-                                  value={line.serialNumbersText}
-                                  aria-invalid={!!errors.serialNumbers}
-                                  onChange={(e) => updateLine(line.key, { serialNumbersText: e.target.value })}
-                                  className="min-h-16 w-full rounded-lg border border-input bg-transparent p-2 text-sm outline-none focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50"
-                                />
-                                <FieldError errors={[errors.serialNumbers ? { message: errors.serialNumbers } : undefined]} />
                               </div>
-                            )}
+                            ) : (
-                            {(!item || item.trackingMode === "None") && (
                               <span className="text-sm text-muted-foreground">—</span>
                             )}
                           </TableCell>
-                          <TableCell className="px-3 py-3 align-top">
+                          <TableCell className="py-3 pr-3 pl-0 align-top">
                             <Button type="button" variant="ghost" size="icon" onClick={() => removeLine(line.key)} aria-label="Remove line">
                               <Trash2 className="size-5" />
                             </Button>
@@ -630,7 +711,86 @@ export default function NewGrnPage() {
               </div>
             )}
 
-            {!poLoading && lines.length > 0 && (
+            {!poLoading && lineTab === "warranty" && (
+              <div className="flex flex-col gap-3">
+                <Button
+                  type="button"
+                  variant="outline"
+                  size="sm"
+                  className="w-fit self-end rounded-full"
+                  onClick={() => setLineTab("lines")}
+                >
+                  <ArrowLeft className="size-4" />
+                  Back to lines
+                </Button>
+
+                {warrantyLines.length === 0 ? (
+                  <p className="rounded-lg border border-dashed p-5 text-base text-muted-foreground">
+                    No warranty-tracked items on this GRN yet — add a line for an item marked
+                    “Warranty” to capture its numbers here.
+                  </p>
+                ) : (
+                  <div className="flex flex-col gap-6">
+                    {warrantyLines.map(({ line, item, units }) => {
+                      const errors = lineErrors[line.key] ?? {}
+                      return (
+                        <div key={line.key} className="flex flex-col gap-2">
+                          <div className="text-sm font-semibold text-foreground">
+                            {item ? `${item.sku} — ${item.name}` : `Item #${line.itemId}`}
+                          </div>
+                          <div className="overflow-x-auto">
+                            <Table className="text-sm">
+                              <TableHeader>
+                                <TableRow>
+                                  <TableHead className="h-10 w-20 px-3 text-sm">Unit</TableHead>
+                                  <TableHead className="h-10 px-3 text-sm">Warranty number</TableHead>
+                                </TableRow>
+                              </TableHeader>
+                              <TableBody>
+                                {Array.from({ length: units }, (_, i) => (
+                                  <TableRow key={`${line.key}-${i}`}>
+                                    <TableCell className="px-3 py-3 align-top text-sm text-muted-foreground">
+                                      {i + 1} of {units}
+                                    </TableCell>
+                                    <TableCell className="px-3 py-3 align-top">
+                                      <Input
+                                        value={line.warrantyNumbers[i] ?? ""}
+                                        aria-invalid={!!errors.warrantyNumbers}
+                                        onChange={(e) => setWarrantyNumberAt(line.key, i, e.target.value)}
+                                        placeholder="e.g. WTY-000123"
+                                        className="h-10 max-w-xs text-sm"
+                                      />
+                                      {i === units - 1 && (
+                                        <FieldError
+                                          errors={[errors.warrantyNumbers ? { message: errors.warrantyNumbers } : undefined]}
+                                        />
+                                      )}
+                                    </TableCell>
+                                  </TableRow>
+                                ))}
+                              </TableBody>
+                            </Table>
+                          </div>
+                        </div>
+                      )
+                    })}
+                  </div>
+                )}
+
+                <Button
+                  type="button"
+                  variant="outline"
+                  size="sm"
+                  className="w-fit self-end rounded-full"
+                  onClick={() => setLineTab("lines")}
+                >
+                  <ArrowLeft className="size-4" />
+                  Back to lines
+                </Button>
+              </div>
+            )}
+
+            {!poLoading && lineTab === "lines" && lines.length > 0 && (
               <div className="flex justify-end gap-3 border-t border-border pt-4 text-base">
                 <span className="text-muted-foreground">Document total (incl. VAT)</span>
                 <span className="font-semibold tabular-nums">
@@ -644,6 +804,7 @@ export default function NewGrnPage() {
             <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-4 text-base text-destructive">{submitError}</div>
           )}
 
+          {lineTab === "lines" && (
             <div className="flex justify-end gap-3">
               <Link href="/dashboard/receiving/grn" className={cn(buttonVariants({ variant: "outline", size: "lg" }))}>
                 Cancel
@@ -652,6 +813,7 @@ export default function NewGrnPage() {
                 {submitting ? "Creating…" : "Create GRN"}
               </Button>
             </div>
+          )}
         </>
       )}
     </div>

Frontend/erp-system/lib/validations/grn.ts

@@ -3,7 +3,7 @@
 // (over-receipt tolerance, referential existence, concurrency) are never
 // re-implemented here; the server's ProblemDetails is the final word (§3.3).
 import { z } from "zod"
-import { TrackingMode } from "@/types/master-data"
+import { Warranty } from "@/types/master-data"
 
 export const grnHeaderSchema = z.object({
   warehouseId: z.number({ error: "Select a warehouse" }).positive("Select a warehouse"),
@@ -17,9 +17,8 @@ export function validateLine(input: {
   unitCost: string
   discountPct: string
   vatPct: string
-  trackingMode: TrackingMode | null
+  warranty: Warranty | null
-  batchNo: string
+  warrantyNumbers: string[]
-  serialNumbersText: string
 }): Record<string, string> {
   const errors: Record<string, string> = {}
 
@@ -39,27 +38,16 @@ export function validateLine(input: {
   if (input.vatPct !== "" && (Number.isNaN(vatPct) || vatPct < 0 || vatPct > 100))
     errors.vatPct = "VAT must be 0–100%"
 
-  if (input.trackingMode === "Batch" && !input.batchNo.trim()) {
+  if (input.warranty === "Warranty") {
-    errors.batchNo = "Batch number is required for this item"
+    const numbers = input.warrantyNumbers.map((s) => s.trim()).filter((s) => s.length > 0)
-  }
+    if (numbers.length === 0) {
-
+      errors.warrantyNumbers = "Enter one warranty number per unit"
-  if (input.trackingMode === "Serial") {
+    } else if (!Number.isNaN(qty) && numbers.length !== qty) {
-    const serials = splitSerials(input.serialNumbersText)
+      errors.warrantyNumbers = `Enter exactly ${qty || 0} warranty number(s) — got ${numbers.length}`
-    if (serials.length === 0) {
+    } else if (new Set(numbers.map((s) => s.toLowerCase())).size !== numbers.length) {
-      errors.serialNumbers = "Enter one serial number per unit"
+      errors.warrantyNumbers = "Warranty numbers must be unique"
-    } else if (!Number.isNaN(qty) && serials.length !== qty) {
-      errors.serialNumbers = `Enter exactly ${qty || 0} serial number(s) — got ${serials.length}`
-    } else if (new Set(serials).size !== serials.length) {
-      errors.serialNumbers = "Serial numbers must be unique"
     }
   }
 
   return errors
 }
-
-export function splitSerials(text: string): string[] {
-  return text
-    .split(/[\n,]/)
-    .map((s) => s.trim())
-    .filter((s) => s.length > 0)
-}

Frontend/erp-system/types/grn.ts

@@ -22,6 +22,15 @@ export interface BatchInput {
   expiryDate?: string | null
 }
 
+/**
+ * A captured warranty number as returned by the server. The coverage period is not chosen at
+ * receipt — it is snapshotted from the item's own `warrantyPeriodMonths` (set at item create).
+ */
+export interface GrnLineWarrantyNumber {
+  warrantyNo: string
+  warrantyPeriodMonths: number
+}
+
 /** One received line on create (docs/11 §4.1). */
 export interface CreateGrnLineInput {
   poLineId?: number | null
@@ -40,6 +49,11 @@ export interface CreateGrnLineInput {
   vatPct?: number
   holdStatus: HoldStatus
   batch?: BatchInput | null
+  /**
+   * Required, one per received unit (count must equal `qty`), when the item is
+   * warranty-tracked (`Item.warranty === "Warranty"`). Ignored otherwise.
+   */
+  warrantyNumbers?: string[] | null
 }
 
 export interface CreateGrnRequest {
@@ -73,6 +87,7 @@ export interface GrnLine {
   priceVariance: number
   holdStatus: HoldStatus
   batchId: number | null
+  warrantyNumbers: GrnLineWarrantyNumber[]
 }
 
 export interface Grn {

Frontend/erp-system/types/master-data.ts

@@ -9,6 +9,11 @@ import { EntityStatus } from "@/types/common"
  */
 export type StockNature = "Stocked" | "NonStocked" | "Service"
 export type TrackingMode = "None" | "Batch" | "Serial"
+export type Warranty = "NonWarranty" | "Warranty"
+
+/** Warranty coverage lengths offered when an item is marked Warranty. */
+export const WARRANTY_PERIOD_MONTHS_OPTIONS = [3, 6, 12, 18] as const
+export type WarrantyPeriodMonths = (typeof WARRANTY_PERIOD_MONTHS_OPTIONS)[number]
 
 /**
  * Unit of an item's content size — how much one stocked pack holds.
@@ -40,6 +45,9 @@ export interface ItemListItem extends ItemContent {
   defaultVendorId: number | null
   stockNature: StockNature
   trackingMode: TrackingMode
+  warranty: Warranty
+  /** Coverage length in months; set when `warranty` is `"Warranty"`, null otherwise. */
+  warrantyPeriodMonths: WarrantyPeriodMonths | null
   taxClass: string | null
   /** Fixed sale price (Sales only); null ⇒ sell at stock/FIFO value. */
   salePrice: number | null
@@ -72,6 +80,9 @@ export interface Item extends ItemContent {
   defaultVendorId: number | null
   stockNature: StockNature
   trackingMode: TrackingMode
+  warranty: Warranty
+  /** Coverage length in months; set when `warranty` is `"Warranty"`, null otherwise. */
+  warrantyPeriodMonths: WarrantyPeriodMonths | null
   taxClass: string | null
   /** Fixed sale price (Sales only); null ⇒ sell at stock/FIFO value. */
   salePrice: number | null
@@ -95,6 +106,10 @@ export interface CreateItemRequest {
   defaultVendorId?: number | null
   stockNature: StockNature
   trackingMode: TrackingMode
+  /** Defaults to `NonWarranty` server-side when omitted. */
+  warranty?: Warranty
+  /** Required (one of `WARRANTY_PERIOD_MONTHS_OPTIONS`) when `warranty` is `"Warranty"`; ignored otherwise. */
+  warrantyPeriodMonths?: WarrantyPeriodMonths | null
   taxClass?: string | null
   /** Optional fixed sale price (Sales only). Null/omitted ⇒ sell at stock/FIFO value. */
   salePrice?: number | null