Merge pull request 'Feat/po grn' (#12) from feat/po-GRN into Dev

Reviewed-on: #12

Backend/ERPCore/Controllers/PurchaseOrdersController.cs

@@ -57,6 +57,25 @@ public sealed class PurchaseOrdersController : ApiControllerBase
         return Ok(result.Value);
     }
 
+    /// <summary>Submit a Draft PO (Draft → Approved). 409 PO_NOT_EDITABLE if not Draft.</summary>
+    [HttpPost("{poId:int}/submit")]
+    [ProducesResponseType(typeof(PurchaseOrderDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status409Conflict)]
+    public async Task<ActionResult<PurchaseOrderDto>> Submit(int poId, CancellationToken ct)
+        => Ok(await _pos.SubmitAsync(poId, ct));
+
+    /// <summary>Delete a PO — permitted only while Draft (409 PO_NOT_EDITABLE otherwise).</summary>
+    [HttpDelete("{poId:int}")]
+    [ProducesResponseType(StatusCodes.Status204NoContent)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status409Conflict)]
+    public async Task<IActionResult> Delete(int poId, CancellationToken ct)
+    {
+        await _pos.DeleteAsync(poId, ct);
+        return NoContent();
+    }
+
     /// <summary>Approve — no-op in Phase 1 (POs auto-approve); transitions PendingApproval→Approved when enabled.</summary>
     [HttpPost("{poId:int}/approve")]
     [ProducesResponseType(typeof(PurchaseOrderDto), StatusCodes.Status200OK)]

Backend/ERPCore/Domain/Entities/GrnLine.cs

@@ -3,9 +3,13 @@ using ERPCore.Domain.Enums;
 namespace ERPCore.Domain.Entities;
 
 /// <summary>
-/// GRN line (FR-GRN-04..08). <see cref="UnitCost"/> is the PO-derived cost for
-/// PO-based receipts (client cost ignored — 02-SECURITY C.3) or the entered cost
-/// for direct receipts. <see cref="ReceivedValue"/> = qty × unitCost.
+/// GRN line (FR-GRN-04..08). <see cref="UnitCost"/> is the gross cost received at:
+/// entered on the line, defaulting to the PO price when omitted (a per-receipt price
+/// override is now permitted — see docs/02-SECURITY C.3, revised). <see cref="PoUnitPrice"/>
+/// snapshots the PO price at receipt so the variance survives later PO edits.
+/// <see cref="NetUnitCost"/> = unitCost after trade discount — this is what the FIFO layer
+/// costs at (VAT never enters stock value; it is recoverable input tax).
+/// <see cref="ReceivedValue"/> = qty × netUnitCost (after discount, before VAT).
 /// <see cref="HoldStatus"/> gates issuability. Model: docs/10 Part C.3.
 /// </summary>
 public class GrnLine
@@ -31,7 +35,30 @@ public class GrnLine
     public Batch? Batch { get; set; }
 
     public decimal Qty { get; set; }
+
+    /// <summary>Gross unit cost received at (entered, or PO price when omitted).</summary>
     public decimal UnitCost { get; set; }
+
+    /// <summary>Snapshot of the PO line price at receipt; null for direct receipts.</summary>
+    public decimal? PoUnitPrice { get; set; }
+
+    /// <summary>Trade discount percentage (0–100), entered.</summary>
+    public decimal DiscountPct { get; set; }
+
+    /// <summary>UnitCost × (1 − DiscountPct/100) — the inventory (FIFO layer) cost.</summary>
+    public decimal NetUnitCost { get; set; }
+
+    /// <summary>VAT percentage (0–100), entered. Recoverable — does not affect stock value.</summary>
+    public decimal VatPct { get; set; }
+
+    /// <summary>Qty × NetUnitCost × VatPct/100.</summary>
+    public decimal VatAmount { get; set; }
+
+    /// <summary>Qty × NetUnitCost (after discount, before VAT).</summary>
     public decimal ReceivedValue { get; set; }
+
+    /// <summary>Qty × NetUnitCost + VatAmount — payable to the vendor.</summary>
+    public decimal LineTotal { get; set; }
+
     public HoldStatus HoldStatus { get; set; } = HoldStatus.Available;
 }

Backend/ERPCore/Domain/Entities/PoLine.cs

@@ -22,7 +22,7 @@ public class PoLine
     public Warehouse? Warehouse { get; set; }
 
     public decimal Qty { get; set; }
-    public decimal UnitPrice { get; set; }
+    public decimal UnitPrice { get; set; }//
     public decimal Tax { get; set; }
     public decimal QtyReceived { get; set; }
 }

Backend/ERPCore/Dtos/Grn/GrnDtos.cs

@@ -7,7 +7,10 @@ namespace ERPCore.Dtos.Grn;
 
 public sealed record GrnLineDto(
     int GrnLineId, int? PoLineId, int ItemId, int UomId, int? BinId,
-    decimal Qty, decimal UnitCost, decimal ReceivedValue, HoldStatus HoldStatus, int? BatchId);
+    decimal Qty, decimal UnitCost, decimal? PoUnitPrice,
+    decimal DiscountPct, decimal NetUnitCost, decimal VatPct, decimal VatAmount,
+    decimal ReceivedValue, decimal LineTotal, decimal PriceVariance,
+    HoldStatus HoldStatus, int? BatchId);
 
 public sealed record GrnDto(
     int GrnId, string DocNo, int? PoId, int VendorId, int WarehouseId, GrnStatus Status,
@@ -44,8 +47,16 @@ public sealed class CreateGrnLineInput
     [Required] public int UomId { get; set; }
     public int? BinId { get; set; }
     [Range(0.0001, double.MaxValue)] public decimal Qty { get; set; }
-    /// <summary>Used only for direct (no-PO) receipts; ignored when <see cref="PoLineId"/> is set.</summary>
+    /// <summary>
+    /// Gross unit cost. Required for direct (no-PO) receipts. For a PO line it is an optional
+    /// per-receipt price override — when 0/omitted the PO line price is used; when supplied it
+    /// wins and a variance is recorded against the PO snapshot (docs/02-SECURITY C.3, revised).
+    /// </summary>
     [Range(0, double.MaxValue)] public decimal UnitCost { get; set; }
+    /// <summary>Trade discount percentage (0–100). Reduces the inventory cost.</summary>
+    [Range(0, 100)] public decimal DiscountPct { get; set; }
+    /// <summary>VAT percentage (0–100). Recoverable — does not affect stock value.</summary>
+    [Range(0, 100)] public decimal VatPct { get; set; }
     [EnumDataType(typeof(HoldStatus))] public HoldStatus HoldStatus { get; set; } = HoldStatus.Available;
     public BatchInput? Batch { get; set; }
 }

Backend/ERPCore/Dtos/Procurement/PurchaseOrderDtos.cs

@@ -37,6 +37,13 @@ public sealed class CreatePurchaseOrderRequest
     [Required] public int VendorId { get; set; }
     public int? RequisitionId { get; set; }
     [Required, MinLength(1)] public List<CreatePoLineInput> Lines { get; set; } = new();
+
+    /// <summary>
+    /// When true the PO is created in <c>Draft</c> (editable/deletable, not yet issued).
+    /// When false (default) it auto-approves on creation, preserving the Requisition→PO
+    /// and RFQ→PO flows unchanged (docs/11 §3.3).
+    /// </summary>
+    public bool SaveAsDraft { get; set; }
 }
 
 public sealed class UpdatePurchaseOrderRequest

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

@@ -37,7 +37,13 @@ public sealed class GrnLineConfiguration : IEntityTypeConfiguration<GrnLine>
 
         builder.Property(l => l.Qty).HasPrecision(18, 4);
         builder.Property(l => l.UnitCost).HasPrecision(18, 6);
+        builder.Property(l => l.PoUnitPrice).HasPrecision(18, 6);
+        builder.Property(l => l.DiscountPct).HasPrecision(9, 4);
+        builder.Property(l => l.NetUnitCost).HasPrecision(18, 6);
+        builder.Property(l => l.VatPct).HasPrecision(9, 4);
+        builder.Property(l => l.VatAmount).HasPrecision(18, 4);
         builder.Property(l => l.ReceivedValue).HasPrecision(18, 4);
+        builder.Property(l => l.LineTotal).HasPrecision(18, 4);
         builder.Property(l => l.HoldStatus).HasConversion<string>().HasMaxLength(20).IsRequired();
 
         builder.HasOne(l => l.Grn).WithMany(g => g.Lines).HasForeignKey(l => l.GrnId).OnDelete(DeleteBehavior.Cascade);

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

@@ -41,7 +41,11 @@ public sealed class PermissionConfiguration : IEntityTypeConfiguration<Permissio
             new Permission { PermissionId = 15, Code = "NAV:products.uom", SubNavItemId = 5 },
             new Permission { PermissionId = 16, Code = "NAV:products.configuration", SubNavItemId = 6 },
             new Permission { PermissionId = 17, Code = "NAV:settings.roles", SubNavItemId = 7 },
-            new Permission { PermissionId = 18, Code = "NAV:settings.users", SubNavItemId = 8 }
+            new Permission { PermissionId = 18, Code = "NAV:settings.users", SubNavItemId = 8 },
+            new Permission { PermissionId = 19, Code = "NAV:procurement.requisitions", SubNavItemId = 9 },
+            new Permission { PermissionId = 20, Code = "NAV:procurement.rfqs", SubNavItemId = 10 },
+            new Permission { PermissionId = 21, Code = "NAV:procurement.purchase-orders", SubNavItemId = 11 },
+            new Permission { PermissionId = 22, Code = "NAV:procurement.purchase-returns", SubNavItemId = 12 }
         );
     }
 }

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

@@ -32,7 +32,12 @@ public sealed class SubNavItemConfiguration : IEntityTypeConfiguration<SubNavIte
             new SubNavItem { SubNavItemId = 5, NavItemId = 2, Code = "products.uom", Label = "UOM", Href = "/dashboard/products/uoms", SortOrder = 5 },
             new SubNavItem { SubNavItemId = 6, NavItemId = 2, Code = "products.configuration", Label = "Configuration", Href = "/dashboard/products/settings", SortOrder = 6 },
             new SubNavItem { SubNavItemId = 7, NavItemId = 9, Code = "settings.roles", Label = "Roles", Href = "/dashboard/settings/roles", SortOrder = 1 },
-            new SubNavItem { SubNavItemId = 8, NavItemId = 9, Code = "settings.users", Label = "Users", Href = "/dashboard/settings/users", SortOrder = 2 }
+            new SubNavItem { SubNavItemId = 8, NavItemId = 9, Code = "settings.users", Label = "Users", Href = "/dashboard/settings/users", SortOrder = 2 },
+            // Procurement (NavItemId 4) children — mirror the hub page order.
+            new SubNavItem { SubNavItemId = 9, NavItemId = 4, Code = "procurement.requisitions", Label = "Requisitions", Href = "/dashboard/procurement/requisitions", SortOrder = 1 },
+            new SubNavItem { SubNavItemId = 10, NavItemId = 4, Code = "procurement.rfqs", Label = "RFQs", Href = "/dashboard/procurement/rfqs", SortOrder = 2 },
+            new SubNavItem { SubNavItemId = 11, NavItemId = 4, Code = "procurement.purchase-orders", Label = "Purchase Orders", Href = "/dashboard/procurement/purchase-orders", SortOrder = 3 },
+            new SubNavItem { SubNavItemId = 12, NavItemId = 4, Code = "procurement.purchase-returns", Label = "Purchase Returns", Href = "/dashboard/procurement/purchase-returns", SortOrder = 4 }
         );
     }
 }

Backend/ERPCore/Infra/Persistence/Migrations/ErpDbContextModelSnapshot.cs

@@ -277,6 +277,10 @@ namespace ERPCore.Infra.Persistence.Migrations
                     b.Property<int?>("BinId")
                         .HasColumnType("integer");
 
+                    b.Property<decimal>("DiscountPct")
+                        .HasPrecision(9, 4)
+                        .HasColumnType("numeric(9,4)");
+
                     b.Property<int>("GrnId")
                         .HasColumnType("integer");
 
@@ -288,9 +292,21 @@ namespace ERPCore.Infra.Persistence.Migrations
                     b.Property<int>("ItemId")
                         .HasColumnType("integer");
 
+                    b.Property<decimal>("LineTotal")
+                        .HasPrecision(18, 4)
+                        .HasColumnType("numeric(18,4)");
+
+                    b.Property<decimal>("NetUnitCost")
+                        .HasPrecision(18, 6)
+                        .HasColumnType("numeric(18,6)");
+
                     b.Property<int?>("PoLineId")
                         .HasColumnType("integer");
 
+                    b.Property<decimal?>("PoUnitPrice")
+                        .HasPrecision(18, 6)
+                        .HasColumnType("numeric(18,6)");
+
                     b.Property<decimal>("Qty")
                         .HasPrecision(18, 4)
                         .HasColumnType("numeric(18,4)");
@@ -306,6 +322,14 @@ namespace ERPCore.Infra.Persistence.Migrations
                     b.Property<int>("UomId")
                         .HasColumnType("integer");
 
+                    b.Property<decimal>("VatAmount")
+                        .HasPrecision(18, 4)
+                        .HasColumnType("numeric(18,4)");
+
+                    b.Property<decimal>("VatPct")
+                        .HasPrecision(9, 4)
+                        .HasColumnType("numeric(9,4)");
+
                     b.HasKey("GrnLineId");
 
                     b.HasIndex("BatchId");
@@ -828,6 +852,30 @@ namespace ERPCore.Infra.Persistence.Migrations
                             PermissionId = 18,
                             Code = "NAV:settings.users",
                             SubNavItemId = 8
+                        },
+                        new
+                        {
+                            PermissionId = 19,
+                            Code = "NAV:procurement.requisitions",
+                            SubNavItemId = 9
+                        },
+                        new
+                        {
+                            PermissionId = 20,
+                            Code = "NAV:procurement.rfqs",
+                            SubNavItemId = 10
+                        },
+                        new
+                        {
+                            PermissionId = 21,
+                            Code = "NAV:procurement.purchase-orders",
+                            SubNavItemId = 11
+                        },
+                        new
+                        {
+                            PermissionId = 22,
+                            Code = "NAV:procurement.purchase-returns",
+                            SubNavItemId = 12
                         });
                 });
 
@@ -1916,6 +1964,46 @@ namespace ERPCore.Infra.Persistence.Migrations
                             NavItemId = 9,
                             SortOrder = 2,
                             Status = "Active"
+                        },
+                        new
+                        {
+                            SubNavItemId = 9,
+                            Code = "procurement.requisitions",
+                            Href = "/dashboard/procurement/requisitions",
+                            Label = "Requisitions",
+                            NavItemId = 4,
+                            SortOrder = 1,
+                            Status = "Active"
+                        },
+                        new
+                        {
+                            SubNavItemId = 10,
+                            Code = "procurement.rfqs",
+                            Href = "/dashboard/procurement/rfqs",
+                            Label = "RFQs",
+                            NavItemId = 4,
+                            SortOrder = 2,
+                            Status = "Active"
+                        },
+                        new
+                        {
+                            SubNavItemId = 11,
+                            Code = "procurement.purchase-orders",
+                            Href = "/dashboard/procurement/purchase-orders",
+                            Label = "Purchase Orders",
+                            NavItemId = 4,
+                            SortOrder = 3,
+                            Status = "Active"
+                        },
+                        new
+                        {
+                            SubNavItemId = 12,
+                            Code = "procurement.purchase-returns",
+                            Href = "/dashboard/procurement/purchase-returns",
+                            Label = "Purchase Returns",
+                            NavItemId = 4,
+                            SortOrder = 4,
+                            Status = "Active"
                         });
                 });
 

Backend/ERPCore/Services/GrnService.cs

@@ -138,8 +138,11 @@ public sealed class GrnService : IGrnService
             if (input.BinId is not null && !await _bins.Query().AnyAsync(b => b.BinId == input.BinId && b.WarehouseId == request.WarehouseId, ct))
                 throw new DomainException(ErrorCodes.Validation, $"Bin {input.BinId} is not in warehouse {request.WarehouseId}.", 422);
 
-            // Cost: PO-derived for PO lines (client cost ignored, C.3); entered for direct.
+            // Cost: for a PO line, the PO price is used unless an override is entered (then it
+            // wins and a variance is recorded against the PO snapshot — docs/02-SECURITY C.3,
+            // revised). Direct receipts always use the entered cost.
             decimal unitCost;
+            decimal? poUnitPrice = null;
             if (input.PoLineId is not null)
             {
                 var poLine = po?.Lines.FirstOrDefault(l => l.PoLineId == input.PoLineId)
@@ -152,13 +155,19 @@ public sealed class GrnService : IGrnService
                     throw new DomainException(ErrorCodes.OverReceiptTolerance,
                         $"Receiving {input.Qty} exceeds the open quantity {openQty} on PO line {input.PoLineId}.", 422);
 
-                unitCost = poLine.UnitPrice;
+                poUnitPrice = poLine.UnitPrice;
+                unitCost = input.UnitCost > 0 ? input.UnitCost : poLine.UnitPrice;
             }
             else
             {
                 unitCost = input.UnitCost;
             }
 
+            // Derived figures are always computed server-side, never accepted from the client.
+            var netUnitCost = Math.Round(unitCost * (1 - input.DiscountPct / 100m), 6, MidpointRounding.AwayFromZero);
+            var receivedValue = Math.Round(input.Qty * netUnitCost, 4, MidpointRounding.AwayFromZero);
+            var vatAmount = Math.Round(receivedValue * input.VatPct / 100m, 4, MidpointRounding.AwayFromZero);
+
             var batch = await ResolveBatchAsync(item, input.Batch, batchCache, ct);
 
             lines.Add(new GrnLine
@@ -170,7 +179,13 @@ public sealed class GrnService : IGrnService
                 Batch = batch, // navigation so EF fixes up BatchId once the batch is inserted
                 Qty = input.Qty,
                 UnitCost = unitCost,
-                ReceivedValue = Math.Round(input.Qty * unitCost, 4, MidpointRounding.AwayFromZero),
+                PoUnitPrice = poUnitPrice,
+                DiscountPct = input.DiscountPct,
+                NetUnitCost = netUnitCost,
+                VatPct = input.VatPct,
+                VatAmount = vatAmount,
+                ReceivedValue = receivedValue,
+                LineTotal = receivedValue + vatAmount,
                 HoldStatus = input.HoldStatus
             });
         }
@@ -220,7 +235,9 @@ public sealed class GrnService : IGrnService
             foreach (var line in grn.Lines.OrderBy(l => l.GrnLineId))
             {
                 var item = await _items.Query().AsNoTracking().FirstAsync(i => i.ItemId == line.ItemId, token);
-                var (qtyBase, unitCostBase) = await ToBaseAsync(item, line.UomId, line.Qty, line.UnitCost, token);
+                // FIFO layer costs at the after-discount net price; VAT is recoverable and never
+                // enters stock value (docs/10 FR-GRN-06, revised).
+                var (qtyBase, unitCostBase) = await ToBaseAsync(item, line.UomId, line.Qty, line.NetUnitCost, token);
 
                 var layer = await _fifo.CreateInboundLayerAsync(
                     line.ItemId, grn.WarehouseId, line.BatchId, null, line.GrnLineId,
@@ -380,5 +397,8 @@ public sealed class GrnService : IGrnService
     private static GrnDto Map(Grn g) => new(
         g.GrnId, g.DocNo, g.PoId, g.VendorId, g.WarehouseId, g.Status, g.CreatedBy, g.CreatedAt, g.PostedAt,
         g.Lines.OrderBy(l => l.GrnLineId).Select(l => new GrnLineDto(
-            l.GrnLineId, l.PoLineId, l.ItemId, l.UomId, l.BinId, l.Qty, l.UnitCost, l.ReceivedValue, l.HoldStatus, l.BatchId)).ToList());
+            l.GrnLineId, l.PoLineId, l.ItemId, l.UomId, 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());
 }

Backend/ERPCore/Services/Interfaces/IPurchaseOrderService.cs

@@ -16,4 +16,10 @@ public interface IPurchaseOrderService
     Task<ETagged<PurchaseOrderDto>> UpdateAsync(int poId, UpdatePurchaseOrderRequest request, uint expectedRowVersion, CancellationToken ct = default);
     Task<PurchaseOrderDto> ApproveAsync(int poId, CancellationToken ct = default);
     Task<PurchaseOrderDto> CancelAsync(int poId, string? reason, CancellationToken ct = default);
+
+    /// <summary>Submit a Draft PO (Draft → Approved). 409 PO_NOT_EDITABLE if not Draft.</summary>
+    Task<PurchaseOrderDto> SubmitAsync(int poId, CancellationToken ct = default);
+
+    /// <summary>Delete a PO — permitted only while Draft, else 409 PO_NOT_EDITABLE.</summary>
+    Task DeleteAsync(int poId, CancellationToken ct = default);
 }

Backend/ERPCore/Services/PurchaseOrderService.cs

@@ -92,9 +92,10 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
                 DocNo = docNo,
                 VendorId = request.VendorId,
                 RequisitionId = request.RequisitionId,
-                // Phase 1: approvalRequired defaults off → auto-approved on creation (FR-PROC-04).
+                // Phase 1: approvalRequired defaults off → auto-approved on creation (FR-PROC-04),
+                // unless the caller explicitly saves a Draft (editable/deletable until submitted).
                 ApprovalRequired = false,
-                Status = PurchaseOrderStatus.Approved,
+                Status = request.SaveAsDraft ? PurchaseOrderStatus.Draft : PurchaseOrderStatus.Approved,
                 CreatedBy = actor,
                 CreatedAt = DateTime.UtcNow,
                 Lines = request.Lines.Select(ToLine).ToList()
@@ -182,8 +183,41 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
         return Map(po);
     }
 
-    private static bool IsEditable(PurchaseOrderStatus status) => status is not (
-        PurchaseOrderStatus.FullyReceived or PurchaseOrderStatus.Closed or PurchaseOrderStatus.Cancelled);
+    public async Task<PurchaseOrderDto> SubmitAsync(int poId, CancellationToken ct = default)
+    {
+        var po = await _pos.Query()
+            .Include(p => p.Lines)
+            .FirstOrDefaultAsync(p => p.PoId == poId, ct)
+            ?? throw new NotFoundException($"Purchase order {poId} was not found.");
+
+        if (po.Status != PurchaseOrderStatus.Draft)
+            throw new DomainException(ErrorCodes.PoNotEditable, $"Purchase order {poId} is {po.Status} and cannot be submitted.", 409);
+
+        // Phase 1: no value gate, so a submitted draft goes straight to Approved (FR-PROC-04).
+        po.Status = PurchaseOrderStatus.Approved;
+        po.UpdatedAt = DateTime.UtcNow;
+        await _uow.SaveChangesAsync(ct);
+
+        return Map(po);
+    }
+
+    public async Task DeleteAsync(int poId, CancellationToken ct = default)
+    {
+        var po = await _pos.Query()
+            .Include(p => p.Lines)
+            .FirstOrDefaultAsync(p => p.PoId == poId, ct)
+            ?? throw new NotFoundException($"Purchase order {poId} was not found.");
+
+        if (po.Status != PurchaseOrderStatus.Draft)
+            throw new DomainException(ErrorCodes.PoNotEditable, $"Purchase order {poId} is {po.Status} and cannot be deleted; only a Draft can be deleted.", 409);
+
+        _pos.Remove(po);
+        await _uow.SaveChangesAsync(ct);
+    }
+
+    // FR-PROC-05 (revised): a PO is editable/deletable only while Draft. Submitting locks it.
+    // Supersedes Phase-1 Option B "freely editable while open" — see docs/10 FR-PROC-05.
+    private static bool IsEditable(PurchaseOrderStatus status) => status is PurchaseOrderStatus.Draft;
 
     private static PoLine ToLine(CreatePoLineInput l) => new()
     {

Backend/PROGRESS.md

@@ -55,7 +55,7 @@ Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit**
 > Requisition/RFQ/PO implemented 2026-07-10. **Live smoke test PASSED** (docNo `PR/RFQ/PO-2026-#####` gap-controlled + incrementing, requestedBy/createdBy = seeded system user, RFQ comparison matrix, duplicate quotation→409, PO auto-approve + server-computed totals matching the spec example `112100/20178/132278`, edit-while-open with recomputed totals + ETag 200/412, PO_NOT_EDITABLE→409 on cancelled, cancel→200, bad reference→422). Same `[~]` reason as §1: the §6 security gate (auth + audit) is not yet wired.
 - [x] Requisition (+ lines) + submit (`POST /requisitions`, `/{id}/submit`, list, get)
 - [x] RFQ + quotations + comparison (`POST /rfqs`, `/{id}/quotations` [one per vendor], `GET /{id}/comparison` matrix)
-- [x] Purchase Order: create (auto-approve, `approvalRequired` flag), edit-while-open (If-Match), approve (no-op), cancel
+- [x] Purchase Order: create (auto-approve **or `saveAsDraft`**, `approvalRequired` flag), edit **Draft-only** (If-Match), **submit** (Draft→Approved), **delete** (Draft-only), approve (no-op), cancel — see the 2026-07-20 entry (FR-PROC-05 revised: draft-lock supersedes edit-while-open)
 - [x] Purchase Return (outbound movement, reason code) — `POST /purchase-returns` auto-posts an outbound FIFO consume via shared `StockMutator`; mandatory Return-context reason (`REASON_CODE_REQUIRED`→400, wrong context→422), references the GRN line for traceability, over-return→`409 STOCK_NEGATIVE_BLOCKED`. Verified. (Cumulative return-vs-received cap still relies on the stock-availability guard.)
 
 > **Deviation (recorded):** `VendorQuotation` is modelled as header + `VendorQuotationLine` (per-item pricing) to satisfy the API contract (docs/11 §3.2); docs/10 Part C.2's scalar `VENDOR_QUOTATION(unit_price, lead_days)` with no item ref cannot represent it. Update the ER model doc to match.
@@ -74,7 +74,7 @@ Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit**
 
 ## 3. Goods Receipt
 > Implemented + **smoke test PASSED** 2026-07-13 (see §4 note for the shared stock verification). Same `[~]` reason as §1/§2: the §6 auth+audit gate.
-- [x] GRN create (against PO / direct), over-receipt tolerance — `unitCost` **PO-derived server-side** (client `999` verified ignored → PO price used, 02-SECURITY C.3); direct receipt requires `vendorId` + entered cost (AR-04); over-receipt → `422 OVER_RECEIPT_TOLERANCE` (verified at open-qty boundary); batch created/reused per (item, batchNo). Serial capture deferred.
+- [x] GRN create (against PO / direct), over-receipt tolerance — `unitCost` **defaults to the PO price but is now overridable per line** (variance recorded vs `poUnitPrice` snapshot — 02-SECURITY C.3 revised 2026-07-20; the old "client cost ignored" block is gone); direct receipt requires `vendorId` + entered cost (AR-04); over-receipt → `422 OVER_RECEIPT_TOLERANCE` (verified at open-qty boundary); batch created/reused per (item, batchNo). Serial capture deferred. **Discount/VAT added** — see the 2026-07-20 entry.
 - [x] GRN confirm → FIFO layer + ledger + PO `qtyReceived` (single UoW txn) — verified: layers+ledger posted, running balance, PO → PartiallyReceived/FullyReceived, UOM→base conversion (10 Box-12 → 120 base @10). **Idempotent** re-confirm verified (no double-post). Note: `Idempotency-Key` accepted but idempotency is resource-state based (already-Confirmed replays existing result); a keyed idempotency store is deferred.
 - [x] Inspection hold release / reject — Release fully verified (OnHold excluded from `available`, then released). Reject removes on-hand + posts a reversing ledger entry; formal link to a Purchase Return is deferred (§3.4).
 
@@ -111,6 +111,16 @@ Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit**
 ## Done
 <!-- move [x] items here with date + note if the active list grows long -->
 
+### 2026-07-20 — PO draft lifecycle + GRN discount/VAT/price-override (migration `AddGrnPricingAndPoDraft`)
+- **PO draft lifecycle (FR-PROC-05 revised).** `CreatePurchaseOrderRequest.SaveAsDraft` (default `false` → auto-approve unchanged; `true` → `Draft`). New `POST /purchase-orders/{id}/submit` (Draft→Approved, else `409 PO_NOT_EDITABLE`) and `DELETE /purchase-orders/{id}` (Draft-only, else 409). `IsEditable` narrowed from "not FullyReceived/Closed/Cancelled" to **`Draft` only** — so `PUT` now 409s on any submitted PO. **Option B ("freely edit while open") is superseded**; docs/10 FR-PROC-05, docs/11 §3.3 updated. ⚠️ **Every pre-existing PO is `Approved` and therefore now uneditable/undeletable** — intended, not a regression. No schema change (reuses the existing `Draft` enum value).
+- **GRN discount + VAT + price override.** `GrnLine` gained `PoUnitPrice`(nullable snapshot), `DiscountPct`, `NetUnitCost`, `VatPct`, `VatAmount`, `LineTotal`. All derived figures **server-computed**, never client-supplied. FIFO layer + ledger now cost at **`NetUnitCost`** (after discount) — VAT is recoverable and never enters stock value (docs/10 FR-GRN-06 revised). For a PO line, `unitCost` defaults to the PO price but an entered override wins and a **variance** is recorded against `PoUnitPrice` (02-SECURITY C.3 revised — the "client cost ignored, decision locked" control is deliberately loosened; the variance trail + audit log are the compensating control). Multi-GRN-per-PO at differing prices (the 20/50/30 case) already worked via `openQty`/`QtyReceived` and is untouched.
+- **Migration** `AddGrnPricingAndPoDraft` — hand-added a data backfill (`UPDATE grn_lines SET NetUnitCost = UnitCost, LineTotal = ReceivedValue`) so existing GRN lines stay consistent with their already-posted FIFO layers; `PoUnitPrice` left NULL for historical rows (no retroactive variance). `Down()` drops the six columns cleanly.
+- **Verified:** `dotnet build` clean (0/0); migration **Up and Down** exercised against the live DB (rollback to `AddRolesNavPermissions` then re-apply — both `Done`). **Runtime end-to-end PASSED — 22/22 assertions** (Node script, register→cookie session): PO draft→edit→submit→edit/delete-locked (409), draft delete (204→404), plain create still auto-approves; **costing proof** (100 @10, 10% disc, 18% VAT → net 9.00, receivedValue 900, VAT 162, lineTotal 1062, **FIFO layer @9.00, valuation 900 — VAT absent from stock**); multi-GRN 20@10/50@11/30@12 → variances +50/+60, PO FullyReceived, blended valuation 2010.
+
+### 2026-07-20 (2) — Procurement sidebar submenu (migration `AddProcurementSubNav`)
+- The sidebar submenu is driven by seeded `SubNavItem` rows + `GET /auth/me` navCodes; only Products/Settings had children, so **Purchase Orders had no sidebar section**. Added 4 `SubNavItem`s (ids 9–12, `NavItemId 4`) + 4 `Permission`s (ids 19–22) for Requisitions/RFQs/Purchase Orders/Purchase Returns via `AddProcurementSubNav`. The migration also grants the 4 to any role already holding the parent `NAV:procurement` (raw SQL, `ON CONFLICT DO NOTHING`); `Down()` removes the grants then the rows.
+- **Found:** the `Admin` role (`RoleId 2`) was never granted `NAV:procurement` at all (nor Vendors), so its whole Procurement branch was hidden — granted the parent + 4 children directly. **Verified:** `/auth/me` for Admin returns `procurement` + all 4 children; frontend `tsc`/`eslint` clean.
+
 ### 2026-07-09 — Bootstrap verified + Master Data (§1) implemented
 - Bootstrap scaffolding confirmed against 00-CORE §5 (solution, packages, `Program.cs` wiring, UoW, generic repo, `ICurrentUser`, ProblemDetails handler). Added enum-as-string JSON (`JsonStringEnumConverter`) and registered the 5 master-data services.
 - Domain: 3 enums (`ItemType`, `TrackingMode`, `EntityStatus`) + 8 entities (Category, Uom, UomConversion, Item, ItemReorder, Vendor, Warehouse, Bin) with one `IEntityTypeConfiguration` each; FKs `Restrict` (masters deactivate, not cascade-delete), unique indexes (SKU, vendor/warehouse code, uom name, bin code per-warehouse), decimal precision, `xmin` concurrency token on Item/Vendor.

Frontend/PROGRESS.md

@@ -39,12 +39,12 @@ Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit**
 ## 3. Procurement screens
 - [~] Requisition (`app/dashboard/procurement/requisitions` list, `/new` create, `/[id]` detail + Submit) — FR-PROC-01
 - [~] RFQ + quotations + comparison view (`.../rfqs` list, `/new` create with vendor multi-invite, `/[id]` detail: lines, comparison matrix, record-quotation form, "Create PO from vendor") — FR-PROC-02
-- [~] Purchase Order (`.../purchase-orders` list, `/new` create — auto-approved, prefillable from a Requisition or an RFQ+vendor quotation via query params — `/[id]` detail: edit-while-open with ETag/If-Match, Cancel with reason) — FR-PROC-03..07
+- [~] Purchase Order (`.../purchase-orders` list, `/new` create — **Save as draft** or **Create & submit** (auto-approve), prefillable from a Requisition or an RFQ+vendor quotation via query params — `/[id]` detail: **Draft** is editable (ETag/If-Match) with **Submit** + **Delete**; a submitted/open PO is read-only with **Cancel** (with reason)) — FR-PROC-03..07. **2026-07-20:** rewired to the draft lifecycle — `isPoEditable` is now `Draft`-only, `submit`/`remove` added to `lib/api/purchase-orders.ts`, `saveAsDraft` on the create request. See the 2026-07-20 entry.
 - [~] Purchase Return (`.../purchase-returns` list, `/new` create against a Confirmed/Closed GRN's lines) — FR-PROC-08; also reachable from a `Rejected` GRN line via a "Create Return" button on the GRN detail page
 
 ## 4. Receiving screens
 - [~] GRN list (`app/dashboard/receiving/grn/page.tsx`) — loading/empty/error states, links to detail
-- [~] GRN create (`app/dashboard/receiving/grn/new/page.tsx`) — "Against PO" (picks an Approved/PartiallyReceived PO, prefills open lines) and "Direct receipt" (vendor + manual lines) modes; per-line bin, qty, unit cost, hold status, and batch (batchNo+expiryDate) or serial-number-list capture driven by the item's `trackingMode`
+- [~] GRN create (`app/dashboard/receiving/grn/new/page.tsx`) — "Against PO" (picks an Approved/PartiallyReceived PO, prefills open lines) and "Direct receipt" (vendor + manual lines) modes; per-line bin, qty, unit cost, **discount % / VAT %** (with live after-discount/after-VAT line total + a per-row PO-price variance hint and a document total), hold status, and batch (batchNo+expiryDate) or serial-number-list capture driven by the item's `trackingMode`. **2026-07-20:** discount/VAT/variance added — see the 2026-07-20 entry.
 - [~] GRN confirm (`app/dashboard/receiving/grn/[id]/page.tsx`) — renders returned `createdLayers`/`ledgerRefs`/`poStatus` as a confirmation panel (20-FRONTEND §4); sends a stable `Idempotency-Key` per detail-page session
 - [~] Inspection hold release / reject — Release/Reject buttons per on-hold line, shown once the GRN is `Confirmed`
 - Sidebar: added "Receiving" nav entry (`components/Layouts/AppSidebar.tsx`) → `/dashboard/receiving/grn`
@@ -90,6 +90,14 @@ Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit**
 ## Done
 <!-- move [x] items here with date + note if the active list grows long -->
 
+### 2026-07-20 — PO draft lifecycle + GRN discount/VAT/price-override (backend + frontend, same pass)
+- **PO draft lifecycle.** `lib/api/purchase-orders.ts`: `isPoEditable` narrowed to `status === "Draft"` (was the three-status exclusion); added `submit(poId)` and `remove(poId)`. `types/procurement.ts`: `saveAsDraft?` on `CreatePurchaseOrderRequest`; `UpdatePurchaseOrderRequest` now `Omit`s it. `/new`: the single "Create PO" button split into **Save as draft** / **Create & submit**. `/[id]`: **Draft** shows the editable line grid + **Submit** + **Delete draft**; an issued-but-open PO (`Approved`/`PartiallyReceived`) is read-only with **Cancel PO** (with reason, disabled once receipts exist); closed/cancelled are terminal. The old Cancel button was gated on `isPoEditable` — that would have shown Cancel only for Draft, so the affordances were re-split into `editable` (Draft) vs `cancellable` (Approved/PartiallyReceived).
+- **GRN discount/VAT/variance.** `types/grn.ts`: `discountPct`/`vatPct` on `CreateGrnLineInput`; `poUnitPrice`/`discountPct`/`netUnitCost`/`vatPct`/`vatAmount`/`lineTotal`/`priceVariance` on `GrnLine`. `/new`: per-line Disc %/VAT % inputs, a client mirror of the server arithmetic (`computeLine`, display-only — server stays authoritative) driving a live Line total + document total, and a PO-price variance hint when the entered unit cost differs from the prefilled PO price. `/[id]`: renders the full cost breakdown (unit cost + variance, disc %, net cost, received value, VAT, line total) and a stock-value/VAT/document-total footer. `lib/validations/grn.ts`: 0–100 range checks on the two percentages.
+- **Deliberately not touched:** the item picker already showed `sku — name` (the request's stated need); multi-GRN-per-PO and adding a non-PO item to a PO GRN already worked. Vendor stays PO-derived (non-selectable) for a PO-based GRN — selecting a different vendor than the PO's would be wrong.
+- **Select trigger showed the id, not the label (global fix).** Base UI's `Select.Value` renders the raw selected value unless the `Select.Root` is given an `items` map — the popup items unmount when closed, so their text isn't available to the trigger (confirmed in `@base-ui/react`'s `resolveSelectedLabel`, which `find`s `items` by value and only falls back to stringifying the value when none is supplied). Fixed once in the shared wrapper (`components/ui/select.tsx`): `Select` now walks its own `SelectItem` children and derives the `items` array automatically, so all ~60 `<SelectValue>` call sites across 26 files show the selected label without any per-site change. `tsc`/`eslint` clean; verified against Base UI's label-resolution source.
+- **Procurement sidebar submenu.** The sidebar builds submenus from backend-seeded `SubNavItem` rows filtered by `GET /auth/me`'s `navCodes`; only Products and Settings had children, so Purchase Orders had no sidebar section (only reachable via the Procurement hub card). Added a `children` array to the Procurement nav entry (`components/Layouts/AppSidebar.tsx`) — Requisitions, RFQs, Purchase Orders, Purchase Returns — matching new backend sub-nav codes. Also found the Admin role (`RoleId 2`) was never granted `NAV:procurement` at all, so the whole Procurement branch was hidden for it; granted the parent + 4 children. **Verified:** `/auth/me` for Admin now returns all five procurement codes → submenu renders. Stale PO hub-card copy ("freely editable while open") updated to the draft/submit wording.
+- **Verified:** `tsc --noEmit` clean; `eslint` unchanged from baseline (7 pre-existing `set-state-in-effect` on the PO/GRN screens before and after — 0 new issues, confirmed by stashing and re-counting). Runtime browser verification is the next step in this pass.
+
 ### 2026-07-17 — connected to the real API (mock-data.ts deleted)
 
 **The app now talks to ERPCore.** Every `lib/api/*.ts` module calls the backend; `lib/api/mock-data.ts` is gone. This is the pass the 2026-07-15 note anticipated.

Frontend/erp-system/app/dashboard/procurement/page.tsx

@@ -18,7 +18,7 @@ const areas: { title: string; description: string; href: string; icon: LucideIco
   },
   {
     title: "Purchase Orders",
-    description: "Auto-approved on creation, freely editable while open, cancellable before receipt.",
+    description: "Save as draft (editable/deletable) or submit to lock; cancel an issued PO before receipt.",
     href: "/dashboard/procurement/purchase-orders",
     icon: ShoppingCart,
   },

Frontend/erp-system/app/dashboard/procurement/purchase-orders/[id]/page.tsx

@@ -3,7 +3,7 @@
 import { useEffect, useState } from "react"
 import { useParams, useRouter } from "next/navigation"
 import Link from "next/link"
-import { AlertTriangle, ArrowLeft, Ban, Plus, Save, Trash2 } from "lucide-react"
+import { AlertTriangle, ArrowLeft, Ban, Plus, Save, Send, Trash2 } from "lucide-react"
 
 import { isPoEditable, purchaseOrdersApi } from "@/lib/api/purchase-orders"
 import { warehousesApi } from "@/lib/api/warehouses"
@@ -65,6 +65,8 @@ export default function PurchaseOrderDetailPage() {
   const [showCancelForm, setShowCancelForm] = useState(false)
   const [cancelReason, setCancelReason] = useState("")
   const [cancelling, setCancelling] = useState(false)
+  const [submitting, setSubmitting] = useState(false)
+  const [deleting, setDeleting] = useState(false)
 
   function toDraftLines(order: PurchaseOrder): DraftLine[] {
     return order.lines.map((l) => ({
@@ -185,6 +187,39 @@ export default function PurchaseOrderDetailPage() {
     }
   }
 
+  async function handleSubmitPo() {
+    if (!po) return
+    setSaveError(null)
+    setSubmitting(true)
+    try {
+      const updated = await purchaseOrdersApi.submit(po.poId)
+      setPo(updated)
+      setLines(toDraftLines(updated))
+      toast.success("Purchase order submitted", `${updated.docNo} — now ${updated.status} and locked for editing.`)
+    } catch (err) {
+      setSaveError(errorMessage(err))
+      toast.error("Could not submit purchase order", errorMessage(err))
+    } finally {
+      setSubmitting(false)
+    }
+  }
+
+  async function handleDelete() {
+    if (!po) return
+    if (!window.confirm(`Delete draft ${po.docNo}? This cannot be undone.`)) return
+    setSaveError(null)
+    setDeleting(true)
+    try {
+      await purchaseOrdersApi.remove(po.poId)
+      toast.success("Draft deleted", po.docNo)
+      router.push("/dashboard/procurement/purchase-orders")
+    } catch (err) {
+      setSaveError(errorMessage(err))
+      toast.error("Could not delete purchase order", errorMessage(err))
+      setDeleting(false)
+    }
+  }
+
   async function handleCancel() {
     if (!po) return
     if (!cancelReason.trim()) {
@@ -226,6 +261,9 @@ export default function PurchaseOrderDetailPage() {
 
   const editable = isPoEditable(po.status) && !conflict
   const hasReceipts = po.lines.some((l) => l.qtyReceived > 0)
+  // A submitted-but-still-open PO (issued to the vendor) is cancellable with a reason;
+  // a Draft is deleted instead, and closed/cancelled POs are terminal.
+  const cancellable = po.status === "Approved" || po.status === "PartiallyReceived"
 
   return (
     <div className="flex flex-col gap-6">
@@ -245,7 +283,20 @@ export default function PurchaseOrderDetailPage() {
           </div>
         </div>
 
-        {isPoEditable(po.status) && !showCancelForm && (
+        <div className="flex items-center gap-3">
+          {po.status === "Draft" && (
+            <>
+              <Button variant="outline" size="lg" onClick={handleSubmitPo} disabled={submitting || deleting}>
+                <Send className="size-5" />
+                {submitting ? "Submitting…" : "Submit"}
+              </Button>
+              <Button variant="destructive" size="lg" onClick={handleDelete} disabled={deleting || submitting}>
+                <Trash2 className="size-5" />
+                {deleting ? "Deleting…" : "Delete draft"}
+              </Button>
+            </>
+          )}
+          {cancellable && !showCancelForm && (
             <Button
               variant="destructive"
               size="lg"
@@ -258,6 +309,7 @@ export default function PurchaseOrderDetailPage() {
             </Button>
           )}
         </div>
+      </div>
 
       {showCancelForm && (
         <div className="flex flex-col gap-3 rounded-xl border border-destructive/30 bg-destructive/5 p-5">

Frontend/erp-system/app/dashboard/procurement/purchase-orders/new/page.tsx

@@ -43,8 +43,12 @@ function newKey() {
   return `poline-${keySeq}`
 }
 
+// Unit price and tax are no longer entered at PO creation — pricing is captured at GRN
+// receipt (with discount/VAT there). They default to 0 here and stay off the form, but
+// remain on the payload because the backend line DTO still requires them; a PO prefilled
+// from an RFQ keeps its negotiated price (below).
 function emptyLine(): DraftLine {
-  return { key: newKey(), itemId: null, uomId: null, warehouseId: null, qty: "", unitPrice: "", tax: "0.18" }
+  return { key: newKey(), itemId: null, uomId: null, warehouseId: null, qty: "", unitPrice: "0", tax: "0" }
 }
 
 function NewPurchaseOrderContent() {
@@ -98,8 +102,8 @@ function NewPurchaseOrderContent() {
                 uomId: null,
                 warehouseId: null,
                 qty: String(l.qty),
-                unitPrice: "",
-                tax: "0.18",
+                unitPrice: "0",
+                tax: "0",
               })
             )
           )
@@ -124,8 +128,8 @@ function NewPurchaseOrderContent() {
                 uomId: null,
                 warehouseId: null,
                 qty: String(l.qty),
-                unitPrice: cell ? String(cell.unitPrice) : "",
-                tax: "0.18",
+                unitPrice: cell ? String(cell.unitPrice) : "0",
+                tax: "0",
               }
             })
           )
@@ -151,7 +155,7 @@ function NewPurchaseOrderContent() {
     return items?.find((i) => i.itemId === itemId) ?? null
   }
 
-  async function handleSubmit() {
+  async function handleSubmit(saveAsDraft: boolean) {
     setHeaderError(null)
     setSubmitError(null)
 
@@ -197,8 +201,12 @@ function NewPurchaseOrderContent() {
         vendorId,
         requisitionId: requisitionId ?? (rfqId ? undefined : null),
         lines: payloadLines,
+        saveAsDraft,
       })
-      toast.success("Purchase order created", `${po.docNo} — auto-approved (FR-PROC-04).`)
+      toast.success(
+        "Purchase order created",
+        saveAsDraft ? `${po.docNo} — saved as draft.` : `${po.docNo} — auto-approved (FR-PROC-04).`
+      )
       router.push(`/dashboard/procurement/purchase-orders/${po.poId}`)
     } catch (err) {
       setSubmitError(errorMessage(err))
@@ -274,8 +282,6 @@ function NewPurchaseOrderContent() {
                       <TableHead className="h-12 w-28 px-3 text-sm">UOM</TableHead>
                       <TableHead className="h-12 w-40 px-3 text-sm">Warehouse</TableHead>
                       <TableHead className="h-12 w-24 px-3 text-sm">Qty</TableHead>
-                      <TableHead className="h-12 w-28 px-3 text-sm">Unit price</TableHead>
-                      <TableHead className="h-12 w-24 px-3 text-sm">Tax</TableHead>
                       <TableHead className="h-12 w-10 px-3" />
                     </TableRow>
                   </TableHeader>
@@ -348,30 +354,6 @@ function NewPurchaseOrderContent() {
                             />
                             <FieldError errors={[errors.qty ? { message: errors.qty } : undefined]} />
                           </TableCell>
-                          <TableCell className="px-3 py-3 align-top">
-                            <Input
-                              type="number"
-                              min="0"
-                              step="any"
-                              value={line.unitPrice}
-                              aria-invalid={!!errors.unitPrice}
-                              onChange={(e) => updateLine(line.key, { unitPrice: e.target.value })}
-                              className="h-11 text-base"
-                            />
-                            <FieldError errors={[errors.unitPrice ? { message: errors.unitPrice } : undefined]} />
-                          </TableCell>
-                          <TableCell className="px-3 py-3 align-top">
-                            <Input
-                              type="number"
-                              min="0"
-                              step="0.01"
-                              value={line.tax}
-                              aria-invalid={!!errors.tax}
-                              onChange={(e) => updateLine(line.key, { tax: e.target.value })}
-                              className="h-11 text-base"
-                            />
-                            <FieldError errors={[errors.tax ? { message: errors.tax } : undefined]} />
-                          </TableCell>
                           <TableCell className="px-3 py-3 align-top">
                             <Button type="button" variant="ghost" size="icon" onClick={() => removeLine(line.key)} aria-label="Remove line">
                               <Trash2 className="size-5" />
@@ -394,8 +376,11 @@ function NewPurchaseOrderContent() {
             <Link href="/dashboard/procurement/purchase-orders" className={cn(buttonVariants({ variant: "outline", size: "lg" }))}>
               Cancel
             </Link>
-            <Button size="lg" type="button" onClick={handleSubmit} disabled={submitting}>
-              {submitting ? "Creating…" : "Create PO"}
+            <Button size="lg" type="button" variant="outline" onClick={() => handleSubmit(true)} disabled={submitting}>
+              {submitting ? "Saving…" : "Save as draft"}
+            </Button>
+            <Button size="lg" type="button" onClick={() => handleSubmit(false)} disabled={submitting}>
+              {submitting ? "Creating…" : "Create & submit"}
             </Button>
           </div>
         </>

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

@@ -158,6 +158,7 @@ export default function GrnDetailPage() {
         </div>
       )}
 
+      <div className="overflow-x-auto">
       <Table className="text-base">
         <TableHeader>
           <TableRow>
@@ -165,8 +166,12 @@ export default function GrnDetailPage() {
             <TableHead className="h-12 px-3 text-sm">UOM</TableHead>
             <TableHead className="h-12 px-3 text-sm">Bin</TableHead>
             <TableHead className="h-12 px-3 text-sm">Qty</TableHead>
-            <TableHead className="h-12 px-3 text-sm">Unit cost</TableHead>
-            <TableHead className="h-12 px-3 text-sm">Received value</TableHead>
+            <TableHead className="h-12 px-3 text-sm text-right">Unit cost</TableHead>
+            <TableHead className="h-12 px-3 text-sm text-right">Disc %</TableHead>
+            <TableHead className="h-12 px-3 text-sm text-right">Net cost</TableHead>
+            <TableHead className="h-12 px-3 text-sm text-right">Received value</TableHead>
+            <TableHead className="h-12 px-3 text-sm text-right">VAT</TableHead>
+            <TableHead className="h-12 px-3 text-sm text-right">Line total</TableHead>
             <TableHead className="h-12 px-3 text-sm">Hold status</TableHead>
             {grn.status === "Confirmed" && <TableHead className="h-12 px-3 text-sm">Actions</TableHead>}
           </TableRow>
@@ -180,8 +185,22 @@ export default function GrnDetailPage() {
                 <TableCell className="px-3 py-3.5">{uomFor(line.uomId)}</TableCell>
                 <TableCell className="px-3 py-3.5">{binFor(line.binId)}</TableCell>
                 <TableCell className="px-3 py-3.5">{line.qty}</TableCell>
-                <TableCell className="px-3 py-3.5">{line.unitCost.toFixed(2)}</TableCell>
-                <TableCell className="px-3 py-3.5">{line.receivedValue.toFixed(2)}</TableCell>
+                <TableCell className="px-3 py-3.5 text-right tabular-nums">
+                  {line.unitCost.toFixed(2)}
+                  {line.poUnitPrice !== null && line.priceVariance !== 0 && (
+                    <span className="block text-xs text-warning">
+                      PO {line.poUnitPrice.toFixed(2)} · var {line.priceVariance > 0 ? "+" : ""}{line.priceVariance.toFixed(2)}
+                    </span>
+                  )}
+                </TableCell>
+                <TableCell className="px-3 py-3.5 text-right tabular-nums">{line.discountPct.toFixed(2)}</TableCell>
+                <TableCell className="px-3 py-3.5 text-right tabular-nums">{line.netUnitCost.toFixed(2)}</TableCell>
+                <TableCell className="px-3 py-3.5 text-right tabular-nums">{line.receivedValue.toFixed(2)}</TableCell>
+                <TableCell className="px-3 py-3.5 text-right tabular-nums">
+                  {line.vatAmount.toFixed(2)}
+                  <span className="block text-xs text-muted-foreground">{line.vatPct.toFixed(2)}%</span>
+                </TableCell>
+                <TableCell className="px-3 py-3.5 text-right tabular-nums font-medium">{line.lineTotal.toFixed(2)}</TableCell>
                 <TableCell className="px-3 py-3.5">
                   <HoldStatusBadge status={line.holdStatus} />
                 </TableCell>
@@ -229,5 +248,21 @@ export default function GrnDetailPage() {
         </TableBody>
       </Table>
       </div>
+
+      <div className="flex justify-end gap-8 border-t border-border pt-4 text-base">
+        <div className="flex gap-3">
+          <span className="text-muted-foreground">Stock value (excl. VAT)</span>
+          <span className="tabular-nums">{grn.lines.reduce((s, l) => s + l.receivedValue, 0).toFixed(2)}</span>
+        </div>
+        <div className="flex gap-3">
+          <span className="text-muted-foreground">VAT</span>
+          <span className="tabular-nums">{grn.lines.reduce((s, l) => s + l.vatAmount, 0).toFixed(2)}</span>
+        </div>
+        <div className="flex gap-3">
+          <span className="text-muted-foreground">Document total</span>
+          <span className="font-semibold tabular-nums">{grn.lines.reduce((s, l) => s + l.lineTotal, 0).toFixed(2)}</span>
+        </div>
+      </div>
+    </div>
   )
 }

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

@@ -37,12 +37,28 @@ interface DraftLine {
   binId: number | null
   qty: string
   unitCost: string
+  /** PO line price when prefilled from a PO; drives the variance hint. */
+  poUnitPrice: number | null
+  discountPct: string
+  vatPct: string
   holdStatus: HoldStatus
   batchNo: string
   expiryDate: string
   serialNumbersText: string
 }
 
+/** Mirror of the server's line arithmetic — display only (docs/20 §3, server stays authoritative). */
+function computeLine(l: DraftLine) {
+  const qty = Number(l.qty) || 0
+  const gross = Number(l.unitCost) || 0
+  const disc = Number(l.discountPct) || 0
+  const vat = Number(l.vatPct) || 0
+  const netUnitCost = gross * (1 - disc / 100)
+  const receivedValue = qty * netUnitCost
+  const vatAmount = receivedValue * (vat / 100)
+  return { netUnitCost, receivedValue, vatAmount, lineTotal: receivedValue + vatAmount }
+}
+
 let keySeq = 0
 function newKey() {
   keySeq += 1
@@ -58,6 +74,9 @@ function emptyLine(): DraftLine {
     binId: null,
     qty: "",
     unitCost: "",
+    poUnitPrice: null,
+    discountPct: "0",
+    vatPct: "0",
     holdStatus: "Available",
     batchNo: "",
     expiryDate: "",
@@ -152,6 +171,9 @@ export default function NewGrnPage() {
             binId: null,
             qty: String(l.qty - l.qtyReceived),
             unitCost: String(l.unitPrice),
+            poUnitPrice: l.unitPrice,
+            discountPct: "0",
+            vatPct: "0",
             holdStatus: "Available",
             batchNo: "",
             expiryDate: "",
@@ -211,6 +233,8 @@ export default function NewGrnPage() {
         uomId: line.uomId,
         qty: line.qty,
         unitCost: line.unitCost,
+        discountPct: line.discountPct,
+        vatPct: line.vatPct,
         trackingMode: itemFor(line.itemId)?.trackingMode ?? null,
         batchNo: line.batchNo,
         serialNumbersText: line.serialNumbersText,
@@ -232,6 +256,8 @@ export default function NewGrnPage() {
         binId: l.binId,
         qty: Number(l.qty),
         unitCost: Number(l.unitCost),
+        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,
         serialNumbers: trackingMode === "Serial" ? splitSerials(l.serialNumbersText) : null,
@@ -371,16 +397,20 @@ export default function NewGrnPage() {
             {poLoading && <Skeleton className="h-24 w-full" />}
 
             {!poLoading && lines.length > 0 && (
+              <div className="overflow-x-auto">
               <Table className="text-base">
                 <TableHeader>
                   <TableRow>
                     <TableHead className="h-12 w-56 px-3 text-sm">Item</TableHead>
-                    <TableHead className="h-12 w-28 px-3 text-sm">UOM</TableHead>
-                    <TableHead className="h-12 w-32 px-3 text-sm">Bin</TableHead>
-                    <TableHead className="h-12 w-24 px-3 text-sm">Qty</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-20 px-3 text-sm">Qty</TableHead>
                     <TableHead className="h-12 w-28 px-3 text-sm">Unit cost</TableHead>
-                    <TableHead className="h-12 w-36 px-3 text-sm">Hold status</TableHead>
-                    <TableHead className="h-12 w-48 px-3 text-sm">Batch / Serial</TableHead>
+                    <TableHead className="h-12 w-24 px-3 text-sm">Disc %</TableHead>
+                    <TableHead className="h-12 w-24 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-32 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-10 px-3" />
                   </TableRow>
                 </TableHeader>
@@ -473,6 +503,50 @@ export default function NewGrnPage() {
                             className="h-11 text-base"
                           />
                           <FieldError errors={[errors.unitCost ? { message: errors.unitCost } : undefined]} />
+                          {line.poUnitPrice !== null && Number(line.unitCost) !== line.poUnitPrice && (
+                            <p className="mt-1 text-xs text-warning">
+                              PO price {line.poUnitPrice.toFixed(2)} — variance recorded
+                            </p>
+                          )}
+                        </TableCell>
+                        <TableCell className="px-3 py-3 align-top">
+                          <Input
+                            type="number"
+                            min="0"
+                            max="100"
+                            step="any"
+                            value={line.discountPct}
+                            aria-invalid={!!errors.discountPct}
+                            onChange={(e) => updateLine(line.key, { discountPct: e.target.value })}
+                            className="h-11 text-base"
+                          />
+                          <FieldError errors={[errors.discountPct ? { message: errors.discountPct } : undefined]} />
+                        </TableCell>
+                        <TableCell className="px-3 py-3 align-top">
+                          <Input
+                            type="number"
+                            min="0"
+                            max="100"
+                            step="any"
+                            value={line.vatPct}
+                            aria-invalid={!!errors.vatPct}
+                            onChange={(e) => updateLine(line.key, { vatPct: e.target.value })}
+                            className="h-11 text-base"
+                          />
+                          <FieldError errors={[errors.vatPct ? { message: errors.vatPct } : undefined]} />
+                        </TableCell>
+                        <TableCell className="px-3 py-3 align-top text-right tabular-nums">
+                          {(() => {
+                            const c = computeLine(line)
+                            return (
+                              <div className="flex h-11 flex-col justify-center">
+                                <span>{c.lineTotal.toFixed(2)}</span>
+                                <span className="text-xs text-muted-foreground">
+                                  net {c.receivedValue.toFixed(2)} + VAT {c.vatAmount.toFixed(2)}
+                                </span>
+                              </div>
+                            )
+                          })()}
                         </TableCell>
                         <TableCell className="px-3 py-3 align-top">
                           <Select<HoldStatus>
@@ -533,6 +607,16 @@ export default function NewGrnPage() {
                   })}
                 </TableBody>
               </Table>
+              </div>
+            )}
+
+            {!poLoading && lines.length > 0 && (
+              <div className="flex justify-end gap-6 pr-12 text-base">
+                <span className="text-muted-foreground">Document total (incl. VAT)</span>
+                <span className="font-semibold tabular-nums">
+                  {lines.reduce((sum, l) => sum + computeLine(l).lineTotal, 0).toFixed(2)}
+                </span>
+              </div>
             )}
           </div>
 

Frontend/erp-system/components/Layouts/AppSidebar.tsx

@@ -8,12 +8,14 @@ import {
   Building2,
   ChevronRight,
   ClipboardList,
+  FileText,
   HelpCircle,
   LayoutGrid,
   ListTree,
   Menu,
   Package,
   PackageCheck,
+  PackageX,
   Ruler,
   Settings,
   ShieldCheck,
@@ -56,7 +58,19 @@ const navItems: {
     ],
   },
   { title: "Vendors", code: "vendors", href: "/dashboard/vendors", icon: Truck, chevron: true },
-  { title: "Procurement", code: "procurement", href: "/dashboard/procurement", icon: ClipboardList, chevron: true },
+  {
+    title: "Procurement",
+    code: "procurement",
+    href: "/dashboard/procurement",
+    icon: ClipboardList,
+    chevron: true,
+    children: [
+      { title: "Requisitions", code: "procurement.requisitions", href: "/dashboard/procurement/requisitions", icon: ClipboardList },
+      { title: "RFQs", code: "procurement.rfqs", href: "/dashboard/procurement/rfqs", icon: FileText },
+      { title: "Purchase Orders", code: "procurement.purchase-orders", href: "/dashboard/procurement/purchase-orders", icon: ShoppingCart },
+      { title: "Purchase Returns", code: "procurement.purchase-returns", href: "/dashboard/procurement/purchase-returns", icon: PackageX },
+    ],
+  },
   { title: "Receiving", code: "receiving", href: "/dashboard/receiving/grn", icon: PackageCheck, chevron: true },
   { title: "Stock", code: "stock", href: "/dashboard/stock", icon: Warehouse, chevron: true },
   { title: "Warehouses", code: "warehouses", href: "/dashboard/warehouse", icon: Building2, chevron: true },
@@ -91,18 +105,36 @@ function SidebarContent({
   pathname: string
   isMobile: boolean
 }) {
+  const iconOnly = !isMobile && collapsed
+
+  // Which parent menus are open. Starts with the parent that owns the active
+  // route auto-expanded; user toggles are preserved across navigation.
+  const [expanded, setExpanded] = useState<Record<string, boolean>>({})
+
+  useEffect(() => {
+    const parent = items.find((i) =>
+      i.children?.some((c) => pathname === c.href || pathname.startsWith(`${c.href}/`))
+    )
+    if (parent) {
+      setExpanded((prev) => (prev[parent.code] ? prev : { ...prev, [parent.code]: true }))
+    }
+  }, [pathname, items])
+
+  const toggleExpand = (code: string) =>
+    setExpanded((prev) => ({ ...prev, [code]: !prev[code] }))
+
   return (
     <nav
       className={cn(
-        "flex h-full flex-col rounded-3xl bg-white p-3 shadow-sm ring-1 ring-black/5 transition-[width] duration-200",
+        "flex h-full flex-col rounded-3xl bg-white p-3 shadow-sm ring-1 ring-black/5 transition-[width] duration-300 ease-in-out",
         !isMobile && (collapsed ? "w-20" : "w-64")
       )}
     >
       {/* Header */}
       <div
         className={cn(
-          "mb-10 flex items-center gap-2.5 px-4 py-3",
-          !isMobile && collapsed ? "flex-col-reverse justify-center gap-3 px-0" : "justify-between"
+          "mb-8 flex shrink-0 items-center gap-2.5 px-4 py-3",
+          iconOnly ? "flex-col-reverse justify-center gap-3 px-0" : "justify-between"
         )}
       >
         <Link href="/dashboard" className="flex items-center gap-2.5" onClick={onClose}>
@@ -111,7 +143,7 @@ function SidebarContent({
               <path d="M24 16c-3-8-11-12-16-8s-3 14 6 14c5 0 8.5-2.5 10-6 1.5 3.5 5 6 10 6 9 0 11-10 6-14s-13 0-16 8Z" />
             </svg>
           </div>
-          {(!collapsed || isMobile) && (
+          {!iconOnly && (
             <span className="text-lg font-bold tracking-tight text-slate-900">Hexa ERP</span>
           )}
         </Link>
@@ -126,55 +158,90 @@ function SidebarContent({
         </button>
       </div>
 
-      {/* Nav items */}
-      <ul className="flex flex-col gap-1">
+      {/* Nav items — scrolls internally when it overflows, without a visible
+          scrollbar so the rounded panel stays clean. */}
+      <ul className="flex min-h-0 flex-1 flex-col gap-1 overflow-y-auto [scrollbar-width:none] [&::-webkit-scrollbar]:hidden">
         {items.map((item) => {
           const isActive =
             item.href === "/dashboard" ? pathname === item.href : pathname.startsWith(item.href)
+          const hasChildren = !!item.children?.length && !iconOnly
+          const isOpen = !!expanded[item.code]
 
           return (
             <li key={item.href}>
+              <div
+                className={cn(
+                  "flex items-center rounded-2xl transition-colors",
+                  isActive ? "bg-indigo-50" : "hover:bg-slate-50"
+                )}
+              >
                 <Link
                   href={item.href}
-                title={!isMobile && collapsed ? item.title : undefined}
+                  title={iconOnly ? item.title : undefined}
                   onClick={onClose}
                   className={cn(
-                  "flex items-center gap-3 rounded-2xl px-4 py-3 text-base font-semibold transition-colors",
-                  !isMobile && collapsed && "justify-center px-0",
-                  isActive
-                    ? "bg-indigo-50 text-indigo-600"
-                    : "text-slate-700 hover:bg-slate-50"
+                    "flex flex-1 items-center gap-3 rounded-2xl px-4 py-3 text-base font-semibold",
+                    iconOnly && "justify-center px-0",
+                    isActive ? "text-indigo-600" : "text-slate-700"
                   )}
                 >
                   <item.icon
                     className={cn("size-5 shrink-0", isActive ? "text-indigo-600" : "text-slate-400")}
                   />
-                {(!collapsed || isMobile) && (
+                  {!iconOnly && (
                     <>
                       <span className="flex-1">{item.title}</span>
-                    {item.chevron && !item.children && !isActive && (
-                      <ChevronRight className="size-4 shrink-0 text-slate-300" />
+                      {item.chevron && !hasChildren && (
+                        <ChevronRight
+                          className={cn("size-4 shrink-0", isActive ? "text-indigo-400" : "text-slate-300")}
+                        />
                       )}
                     </>
                   )}
                 </Link>
 
-              {item.children && (!collapsed || isMobile) && (
-                <ul className="mt-1 flex flex-col gap-0.5 pl-11">
+                {hasChildren && (
+                  <button
+                    type="button"
+                    onClick={() => toggleExpand(item.code)}
+                    aria-label={isOpen ? `Collapse ${item.title}` : `Expand ${item.title}`}
+                    aria-expanded={isOpen}
+                    className={cn(
+                      "mr-2 flex size-7 shrink-0 items-center justify-center rounded-lg transition-colors hover:bg-white/60",
+                      isActive ? "text-indigo-500" : "text-slate-400"
+                    )}
+                  >
+                    <ChevronRight
+                      className={cn("size-4 transition-transform duration-300 ease-in-out", isOpen && "rotate-90")}
+                    />
+                  </button>
+                )}
+              </div>
+
+              {hasChildren && (
+                <div
+                  className={cn(
+                    "grid transition-all duration-300 ease-in-out",
+                    isOpen ? "mt-1 grid-rows-[1fr] opacity-100" : "grid-rows-[0fr] opacity-0"
+                  )}
+                >
+                  <div className="overflow-hidden">
+                    <ul className="flex flex-col gap-0.5 pl-11">
                       {(() => {
                         // Longest-matching href wins so a shared prefix (e.g. "Item" and
                         // "Category" both live under /dashboard/products) doesn't light up
                         // more than one sub-item at once.
-                    const activeChild = [...item.children]
+                        const activeChild = [...item.children!]
                           .filter((c) => pathname === c.href || pathname.startsWith(`${c.href}/`))
                           .sort((a, b) => b.href.length - a.href.length)[0]
-                    return item.children.map((child) => {
+                        return item.children!.map((child) => {
                           const childActive = child.href === activeChild?.href
                           return (
                             <li key={child.href}>
                               <Link
                                 href={child.href}
                                 onClick={onClose}
+                                tabIndex={isOpen ? undefined : -1}
                                 className={cn(
                                   "flex items-center gap-2.5 rounded-xl px-3 py-2 text-sm font-medium transition-colors",
                                   childActive
@@ -192,13 +259,15 @@ function SidebarContent({
                         })
                       })()}
                     </ul>
+                  </div>
+                </div>
               )}
             </li>
           )
         })}
       </ul>
 
-      <div className="mt-auto flex items-center justify-center pt-6">
+      <div className="flex items-center justify-center pt-6">
         <div className="flex size-12 items-center justify-center rounded-2xl bg-slate-50 ring-1 ring-black/5">
           <svg viewBox="0 0 48 32" className="h-4 w-6 fill-slate-400">
             <path d="M24 16c-3-8-11-12-16-8s-3 14 6 14c5 0 8.5-2.5 10-6 1.5 3.5 5 6 10 6 9 0 11-10 6-14s-13 0-16 8Z" />

Frontend/erp-system/components/ui/select.tsx

@@ -6,7 +6,40 @@ import { Select as SelectPrimitive } from "@base-ui/react/select"
 import { cn } from "@/lib/utils"
 import { ChevronDownIcon, CheckIcon, ChevronUpIcon } from "lucide-react"
 
-const Select = SelectPrimitive.Root
+// Base UI's `Select.Value` renders the raw selected value (e.g. an id) unless the Root is
+// given an `items` map to resolve the label from — the popup items are unmounted when closed,
+// so their text isn't otherwise available. Rather than pass `items` at all ~60 call sites,
+// this wrapper walks its own `SelectItem` children and derives that map automatically, so the
+// trigger shows the selected item's label instead of its value.
+function collectItems(
+  children: React.ReactNode,
+  acc: { value: unknown; label: React.ReactNode }[]
+) {
+  React.Children.forEach(children, (child) => {
+    if (!React.isValidElement(child)) return
+    if (child.type === SelectItem) {
+      const p = child.props as { value?: unknown; children?: React.ReactNode }
+      acc.push({ value: p.value, label: p.children })
+      return
+    }
+    const nested = (child.props as { children?: React.ReactNode }).children
+    if (nested) collectItems(nested, acc)
+  })
+}
+
+function Select<Value, Multiple extends boolean | undefined = false>(
+  props: SelectPrimitive.Root.Props<Value, Multiple>
+) {
+  const { items, children } = props
+  const derivedItems = React.useMemo(() => {
+    if (items) return items
+    const acc: { value: unknown; label: React.ReactNode }[] = []
+    collectItems(children, acc)
+    return acc.length ? (acc as ReadonlyArray<{ value: Value; label: React.ReactNode }>) : undefined
+  }, [items, children])
+
+  return <SelectPrimitive.Root {...props} items={derivedItems} />
+}
 
 function SelectGroup({ className, ...props }: SelectPrimitive.Group.Props) {
   return (

Frontend/erp-system/lib/api/purchase-orders.ts

@@ -20,10 +20,10 @@ export interface ListPurchaseOrdersParams {
   sort?: string
 }
 
-/** Editable while open (FR-PROC-05, Option B). The server is authoritative — it returns
- *  409 PO_NOT_EDITABLE regardless — this only drives UI affordances. */
+/** Editable/deletable only while Draft (FR-PROC-05, revised — submitting locks the PO).
+ *  The server is authoritative (409 PO_NOT_EDITABLE otherwise); this only drives UI affordances. */
 export function isPoEditable(status: PurchaseOrderStatus): boolean {
-  return status !== "FullyReceived" && status !== "Closed" && status !== "Cancelled"
+  return status === "Draft"
 }
 
 export const purchaseOrdersApi = {
@@ -54,6 +54,16 @@ export const purchaseOrdersApi = {
     return apiRequest<PurchaseOrder>(`/purchase-orders/${poId}/approve`, { method: "POST" })
   },
 
+  /** Submit a Draft PO (Draft → Approved). 409 PO_NOT_EDITABLE if not Draft. */
+  submit(poId: number): Promise<PurchaseOrder> {
+    return apiRequest<PurchaseOrder>(`/purchase-orders/${poId}/submit`, { method: "POST" })
+  },
+
+  /** Delete a Draft PO. 409 PO_NOT_EDITABLE once submitted. */
+  remove(poId: number): Promise<void> {
+    return apiRequest<void>(`/purchase-orders/${poId}`, { method: "DELETE" })
+  },
+
   /** 409 if any receipt exists against the PO. */
   cancel(poId: number, request: CancelPurchaseOrderRequest): Promise<PurchaseOrder> {
     return apiRequest<PurchaseOrder>(`/purchase-orders/${poId}/cancel`, { method: "POST", body: request })

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

@@ -16,6 +16,8 @@ export function validateLine(input: {
   uomId: number | null
   qty: string
   unitCost: string
+  discountPct: string
+  vatPct: string
   trackingMode: TrackingMode | null
   batchNo: string
   serialNumbersText: string
@@ -31,6 +33,14 @@ export function validateLine(input: {
   const unitCost = Number(input.unitCost)
   if (input.unitCost === "" || Number.isNaN(unitCost) || unitCost < 0) errors.unitCost = "Unit cost cannot be negative"
 
+  const discountPct = Number(input.discountPct)
+  if (input.discountPct !== "" && (Number.isNaN(discountPct) || discountPct < 0 || discountPct > 100))
+    errors.discountPct = "Discount must be 0–100%"
+
+  const vatPct = Number(input.vatPct)
+  if (input.vatPct !== "" && (Number.isNaN(vatPct) || vatPct < 0 || vatPct > 100))
+    errors.vatPct = "VAT must be 0–100%"
+
   if (input.trackingMode === "Batch" && !input.batchNo.trim()) {
     errors.batchNo = "Batch number is required for this item"
   }

Frontend/erp-system/types/grn.ts

@@ -29,7 +29,16 @@ export interface CreateGrnLineInput {
   uomId: number
   binId?: number | null
   qty: number
+  /**
+   * Gross unit cost. For a PO line it is an optional per-receipt override — 0/omitted uses
+   * the PO price; a value wins and the server records a variance (docs/02-SECURITY C.3,
+   * revised). Required (> 0) for a direct receipt.
+   */
   unitCost: number
+  /** Trade discount % (0–100). Reduces inventory cost. */
+  discountPct?: number
+  /** VAT % (0–100). Recoverable — does not affect stock value. */
+  vatPct?: number
   holdStatus: HoldStatus
   batch?: BatchInput | null
 }
@@ -49,8 +58,21 @@ export interface GrnLine {
   uomId: number
   binId: number | null
   qty: number
+  /** Gross unit cost received at. */
   unitCost: number
+  /** PO price snapshot at receipt; null for direct receipts. */
+  poUnitPrice: number | null
+  discountPct: number
+  /** After-discount cost — what the FIFO layer is valued at. */
+  netUnitCost: number
+  vatPct: number
+  vatAmount: number
+  /** qty × netUnitCost (after discount, before VAT). */
   receivedValue: number
+  /** qty × netUnitCost + vatAmount — payable to vendor. */
+  lineTotal: number
+  /** (unitCost − poUnitPrice) × qty; 0 for direct receipts. */
+  priceVariance: number
   holdStatus: HoldStatus
   batchId: number | null
 }

Frontend/erp-system/types/procurement.ts

@@ -189,10 +189,12 @@ export interface CreatePurchaseOrderRequest {
   vendorId: number
   requisitionId?: number | null
   lines: CreatePoLineInput[]
+  /** When true the PO is created as an editable/deletable Draft; false (default) auto-approves. */
+  saveAsDraft?: boolean
 }
 
-/** PUT /purchase-orders/{poId} — edit-while-open, same line shape as create (FR-PROC-05, Option B). */
-export type UpdatePurchaseOrderRequest = CreatePurchaseOrderRequest
+/** PUT /purchase-orders/{poId} — edit a Draft only (FR-PROC-05, revised); same line shape as create. */
+export type UpdatePurchaseOrderRequest = Omit<CreatePurchaseOrderRequest, "saveAsDraft">
 
 export interface CancelPurchaseOrderRequest {
   reason?: string | null

docs/02-SECURITY.md

@@ -83,9 +83,9 @@ These are known, deliberately-accepted Phase-1 exposures. Each has a compensatin
 - [ ] Note in review: **AR-01/AR-02/AR-03** apply to these endpoints
 
 ### C.3 GRN
-- [ ] `unitCost` **derived from the PO line server-side**; any client-supplied cost is ignored *(decision locked)*
-- [ ] `receivedValue` computed server-side (qty × PO-line cost), not accepted from client
-- [ ] Direct GRN (no PO) is the exception where cost is entered → extra scrutiny + review flag + audit (**AR-04**)
+- [ ] `unitCost` **defaults to the PO line price**; a per-line override **is now permitted** *(decision revised 2026-07-20 — was "locked, client cost ignored")*. When an override is entered it is used, and the PO price is snapshotted (`poUnitPrice`) so a **`priceVariance` is recorded** against it for review. Rationale: one PO legitimately spans batches received at different prices; the variance trail (plus the audit log) is the compensating control that replaces the old hard block.
+- [ ] **Derived figures stay server-computed** — `netUnitCost`/`receivedValue`/`vatAmount`/`lineTotal` are never accepted from the client, so the client cannot inflate stock value except by an *auditable* unit-cost override. Discount reduces inventory cost; **VAT is recoverable and never enters stock value**.
+- [ ] Direct GRN (no PO) remains the higher-scrutiny path where cost is entered with no PO to compare against → review flag + audit (**AR-04**)
 - [ ] Over-receipt tolerance enforced server-side → `OVER_RECEIPT_TOLERANCE`
 - [ ] On-hold stock is not issuable (FR-WH-07); expired batch blocked
 

docs/10-BACKEND-PHASE1.md

@@ -137,7 +137,7 @@ One base currency; invoicing/3-way match in Accounting (GRN carries data); users
 | FR-PROC-02 | Optional **RFQ**: issue to vendors, record quotations for comparison. | S |
 | FR-PROC-03 | Generate **PO** from PR/RFQ or directly (item, UOM, qty, price, tax, delivery date, warehouse). | M |
 | FR-PROC-04 | **[Phase 1: auto-approve]** Auto-approve PO on creation (status `Approved`). Config flag `approvalRequired` (default off) gates a future approval workflow (authorization matrix); when on, PO cannot issue until approved. `PendingApproval` state + approval fields retained in schema (no migration to enable). | M |
-| FR-PROC-05 | **[Phase 1: Option B — edit-while-open]** PO may be **freely edited while open** (not fully received/closed); changes take effect immediately with an audit entry. Versioned amendments deferred; schema must not preclude adding a version field later. | S |
+| FR-PROC-05 | **[Phase 1: Option B *superseded* 2026-07-20 — draft-lock]** A PO is **editable and deletable only while `Draft`**; **submitting locks it** (Draft → Approved) and no further edit/delete/add-line is allowed — an issued PO is corrected by Cancel-with-reason (blocked once receipts exist) or a reversing document, never edited. Create takes `saveAsDraft` (default `false` → auto-approve, preserving the Requisition→PO / RFQ→PO flows). *Why the reversal:* Option B ("freely edit while open") let an already-issued, vendor-facing PO change silently after the fact; the draft/submit boundary makes "issued to vendor" a real, immutable commitment. Versioned amendments still deferred; schema unchanged (reuses the existing `Draft` enum value). | S |
 | FR-PROC-06 | PO lifecycle: Draft → (PendingApproval →) Approved → PartiallyReceived → FullyReceived → Closed/Cancelled. Phase 1 bypasses PendingApproval via auto-approve. | M |
 | FR-PROC-07 | Support **partial receipt**; PO stays open until fully received or manually closed. | M |
 | FR-PROC-08 | Support **Purchase Return** referencing original GRN/PO line; generates outbound movement. | M |
@@ -151,7 +151,7 @@ One base currency; invoicing/3-way match in Accounting (GRN carries data); users
 | FR-GRN-03 | Support **over/under-receipt tolerances** (per item or global); warn or block beyond tolerance. | S |
 | FR-GRN-04 | Capture **batch + expiry** and/or **serial numbers** for tracked items on receipt. | M |
 | FR-GRN-05 | Allow receipt into **inspection/quarantine hold** (not issuable) pending QC, before QC module exists. | M |
-| FR-GRN-06 | On confirm, each line **creates a FIFO cost layer** at unit cost (PO price + attributable charges; landed cost per §B.1.2.1) and posts an inbound ledger entry. | M |
+| FR-GRN-06 | On confirm, each line **creates a FIFO cost layer** at the **after-discount net unit cost** (`unitCost × (1 − discountPct/100)`) and posts an inbound ledger entry. **VAT never enters stock value** — it is recoverable input tax (revised 2026-07-20). PO price is the default unit cost; a per-line override is permitted and recorded as a variance (see 02-SECURITY C.3, revised). | M |
 | FR-GRN-07 | Record **received value per line** and PO reference for downstream matching. | M |
 | FR-GRN-08 | Assign received stock to a **bin/location** (putaway). | S |
 

docs/11-BACKEND-PHASE1.md

@@ -457,14 +457,15 @@ Query: `q`, `status` (`Open|Closed`), + paging. → list envelope of
 `GET /rfqs/{rfqId}/comparison` → vendor-by-line price matrix.
 
 ### 3.3 Purchase Orders
-> **Phase 1:** `approvalRequired` defaults `false` → PO **auto-approved on creation**. Approve endpoint exists but is a no-op unless enabled (FR-PROC-04). PO **freely editable while open** (Option B, FR-PROC-05).
+> **Phase 1:** `approvalRequired` defaults `false`. Create takes **`saveAsDraft`** (default `false` → **auto-approved on creation**; `true` → `Draft`). Approve endpoint exists but is a no-op unless enabled (FR-PROC-04). **A PO is editable/deletable only while `Draft`; submitting locks it** (FR-PROC-05, revised 2026-07-20 — Option B "freely edit while open" superseded).
 
 #### `POST /purchase-orders`
 ```json
-{ "vendorId": 5, "requisitionId": 210,
+{ "vendorId": 5, "requisitionId": 210, "saveAsDraft": false,
   "lines": [ { "itemId": 1001, "uomId": 1, "warehouseId": 1, "qty": 5000, "unitPrice": 12.50, "tax": 0.18 },
              { "itemId": 1002, "uomId": 1, "warehouseId": 1, "qty": 8000, "unitPrice": 6.20, "tax": 0.18 } ] }
 ```
+`saveAsDraft` optional (default `false`). When `true` the response `status` is `Draft`.
 **201 Created** — `Location: /api/v1/purchase-orders/342`
 ```json
 { "poId": 342, "docNo": "PO-2026-00342", "vendorId": 5, "requisitionId": 210,
@@ -477,7 +478,11 @@ Query: `q`, `status` (`Open|Closed`), + paging. → list envelope of
 `GET /purchase-orders?status=Approved&vendorId=5` → list envelope of PO summaries.
 
 #### `PUT /purchase-orders/{poId}`
-Edit while open (not FullyReceived/Closed/Cancelled); requires `If-Match`. → **200 OK** updated resource; `409 PO_NOT_EDITABLE` if closed.
+Edit a **Draft only**; requires `If-Match`. → **200 OK** updated resource; `409 PO_NOT_EDITABLE` once submitted (any non-Draft status).
+
+#### `POST /purchase-orders/{poId}/submit` → **200 OK** — `Draft → Approved`. `409 PO_NOT_EDITABLE` if not Draft.
+
+#### `DELETE /purchase-orders/{poId}` → **204 No Content** — permitted **only while Draft**; `409 PO_NOT_EDITABLE` once submitted.
 
 #### `POST /purchase-orders/{poId}/approve` → **200 OK** (no-op in Phase 1; transitions PendingApproval→Approved when enabled).
 
@@ -524,15 +529,24 @@ Against a PO (lines default from open PO lines) or direct (`poId: null`, by perm
 ```json
 { "poId": 342, "warehouseId": 1,
   "lines": [ { "poLineId": 900, "itemId": 1001, "uomId": 1, "binId": 45, "qty": 5000,
-      "unitCost": 12.50, "holdStatus": "OnHold",
+      "unitCost": 12.50, "discountPct": 10, "vatPct": 18, "holdStatus": "OnHold",
       "batch": { "batchNo": "B-2607", "expiryDate": "2028-07-01" } } ] }
 ```
-**201 Created** — status `Draft`
+`discountPct`/`vatPct` optional (default 0, range 0–100). `unitCost` on a **PO line** is an optional
+override: 0/omitted uses the PO price; a value wins and a variance is recorded (02-SECURITY C.3, revised).
+On a direct receipt `unitCost` is required.
+**201 Created** — status `Draft`. All derived figures are **server-computed**:
+`netUnitCost = unitCost × (1 − discountPct/100)`, `receivedValue = qty × netUnitCost` (after discount,
+**before** VAT — this is the stock value), `vatAmount = receivedValue × vatPct/100`,
+`lineTotal = receivedValue + vatAmount`, `priceVariance = (unitCost − poUnitPrice) × qty`.
 ```json
 { "grnId": 780, "docNo": "GRN-2026-00780", "poId": 342, "vendorId": 5, "warehouseId": 1,
   "status": "Draft", "createdBy": 17,
   "lines": [ { "grnLineId": 1300, "poLineId": 900, "itemId": 1001, "uomId": 1, "binId": 45,
-      "qty": 5000, "unitCost": 12.50, "receivedValue": 62500.00, "holdStatus": "OnHold", "batchId": 410 } ] }
+      "qty": 5000, "unitCost": 12.50, "poUnitPrice": 12.50, "discountPct": 10.0,
+      "netUnitCost": 11.25, "vatPct": 18.0, "vatAmount": 10125.00,
+      "receivedValue": 56250.00, "lineTotal": 66375.00, "priceVariance": 0.00,
+      "holdStatus": "OnHold", "batchId": 410 } ] }
 ```
 `422 OVER_RECEIPT_TOLERANCE` if qty exceeds open PO qty beyond tolerance.