Merge pull request 'Feat/sales management' (#24) from feat/sales-management into Dev

Reviewed-on: #24

Backend/ERPCore/Controllers/FreeIssuesController.cs

@@ -0,0 +1,78 @@
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+/// <summary>
+/// Thin API alias for free-issue handling. Free issues are modeled as sales slips
+/// with line-level <c>IsFreeIssue</c>/<c>FreeQty</c> flags, so this controller reuses
+/// the existing sales-slip CRUD surface under a more business-friendly route.
+/// </summary>
+[Route("api/v1/free-issues")]
+public sealed class FreeIssuesController : ApiControllerBase
+{
+    private readonly ISalesSlipService _slips;
+
+    public FreeIssuesController(ISalesSlipService slips) => _slips = slips;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(PagedResponse<FreeIssueSummaryDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<FreeIssueSummaryDto>>> List(
+        [FromQuery] PageQuery query,
+        [FromQuery] SalesSlipStatus? status,
+        [FromQuery] int? customerId,
+        [FromQuery] int? warehouseId,
+        CancellationToken ct)
+        => Ok(await _slips.ListFreeIssuesAsync(query, status, customerId, warehouseId, ct));
+
+    [HttpGet("{freeIssueId:int}")]
+    [ProducesResponseType(typeof(FreeIssueDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<FreeIssueDto>> GetById(int freeIssueId, CancellationToken ct)
+    {
+        var result = await _slips.GetFreeIssueAsync(freeIssueId, ct);
+        if (result is null) return NotFound();
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpGet("{freeIssueId:int}/posting-check")]
+    [ProducesResponseType(typeof(SalesSlipPostingCheckDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<SalesSlipPostingCheckDto>> PostingCheck(int freeIssueId, CancellationToken ct)
+        => Ok(await _slips.CheckPostingAsync(freeIssueId, ct));
+
+    [HttpPost]
+    [ProducesResponseType(typeof(FreeIssueDto), StatusCodes.Status201Created)]
+    public async Task<ActionResult<FreeIssueDto>> Create([FromBody] CreateSalesSlipRequest request, CancellationToken ct)
+    {
+        var result = await _slips.CreateAsync(request, ct);
+        SetETag(result.RowVersion);
+        return Created($"/api/v1/free-issues/{result.Value.SalesSlipId}", result.Value);
+    }
+
+    [HttpPut("{freeIssueId:int}")]
+    [ProducesResponseType(typeof(FreeIssueDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status412PreconditionFailed)]
+    public async Task<ActionResult<FreeIssueDto>> Update(int freeIssueId, [FromBody] UpdateSalesSlipRequest request, CancellationToken ct)
+    {
+        var expected = RequireIfMatch();
+        var result = await _slips.UpdateAsync(freeIssueId, request, expected, ct);
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpPost("{freeIssueId:int}/post")]
+    [ProducesResponseType(typeof(FreeIssueDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<FreeIssueDto>> Post(int freeIssueId, CancellationToken ct)
+        => Ok(await _slips.PostAsync(freeIssueId, ct));
+
+    [HttpPost("{freeIssueId:int}/cancel")]
+    [ProducesResponseType(typeof(FreeIssueDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<FreeIssueDto>> Cancel(int freeIssueId, CancellationToken ct)
+        => Ok(await _slips.CancelAsync(freeIssueId, ct));
+}

Backend/ERPCore/Controllers/SalesInvoicesController.cs

@@ -34,6 +34,12 @@ public sealed class SalesInvoicesController : ApiControllerBase
         return Ok(result.Value);
     }
 
+    [HttpGet("{salesInvoiceId:int}/posting-check")]
+    [ProducesResponseType(typeof(SalesInvoicePostingCheckDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<SalesInvoicePostingCheckDto>> PostingCheck(int salesInvoiceId, CancellationToken ct)
+        => Ok(await _invoices.CheckPostingAsync(salesInvoiceId, ct));
+
     [HttpPost]
     [ProducesResponseType(typeof(SalesInvoiceDto), StatusCodes.Status201Created)]
     public async Task<ActionResult<SalesInvoiceDto>> Create([FromBody] CreateSalesInvoiceRequest request, CancellationToken ct)

Backend/ERPCore/Controllers/SalesReportsController.cs

@@ -11,39 +11,25 @@ public sealed class SalesReportsController : ApiControllerBase
 
     public SalesReportsController(ISalesReportService reports) => _reports = reports;
 
-    [HttpGet("daily-summary")]
-    [ProducesResponseType(typeof(IReadOnlyList<SalesDailySummaryRowDto>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<IReadOnlyList<SalesDailySummaryRowDto>>> DailySummary(
-        [FromQuery] DateOnly from, [FromQuery] DateOnly to, CancellationToken ct)
-        => Ok(await _reports.DailySummaryAsync(from, to, ct));
+    [HttpGet]
+    [ProducesResponseType(typeof(IReadOnlyList<SalesReportDefinitionDto>), StatusCodes.Status200OK)]
+    public ActionResult<IReadOnlyList<SalesReportDefinitionDto>> ListReports()
+        => Ok(_reports.ListReports());
 
-    [HttpGet("item-wise")]
-    [ProducesResponseType(typeof(IReadOnlyList<SalesItemSummaryRowDto>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<IReadOnlyList<SalesItemSummaryRowDto>>> ItemWise(
-        [FromQuery] DateOnly from, [FromQuery] DateOnly to, [FromQuery] int? itemId, [FromQuery] int? warehouseId, CancellationToken ct)
-        => Ok(await _reports.ItemSummaryAsync(from, to, itemId, warehouseId, ct));
+    [HttpGet("{reportId}")]
+    [ProducesResponseType(typeof(SalesReportDefinitionDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public ActionResult<SalesReportDefinitionDto> GetReport(string reportId)
+    {
+        var report = _reports.GetReport(reportId);
+        return report is null ? NotFound() : Ok(report);
+    }
 
-    [HttpGet("customer-wise")]
-    [ProducesResponseType(typeof(IReadOnlyList<SalesCustomerSummaryRowDto>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<IReadOnlyList<SalesCustomerSummaryRowDto>>> CustomerWise(
-        [FromQuery] DateOnly from, [FromQuery] DateOnly to, [FromQuery] int? customerId, CancellationToken ct)
-        => Ok(await _reports.CustomerSummaryAsync(from, to, customerId, ct));
-
-    [HttpGet("warehouse-wise")]
-    [ProducesResponseType(typeof(IReadOnlyList<SalesWarehouseSummaryRowDto>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<IReadOnlyList<SalesWarehouseSummaryRowDto>>> WarehouseWise(
-        [FromQuery] DateOnly from, [FromQuery] DateOnly to, [FromQuery] int? warehouseId, CancellationToken ct)
-        => Ok(await _reports.WarehouseSummaryAsync(from, to, warehouseId, ct));
-
-    [HttpGet("discount-summary")]
-    [ProducesResponseType(typeof(IReadOnlyList<SalesDiscountSummaryRowDto>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<IReadOnlyList<SalesDiscountSummaryRowDto>>> DiscountSummary(
-        [FromQuery] DateOnly from, [FromQuery] DateOnly to, CancellationToken ct)
-        => Ok(await _reports.DiscountSummaryAsync(from, to, ct));
-
-    [HttpGet("free-issue-summary")]
-    [ProducesResponseType(typeof(IReadOnlyList<SalesFreeIssueSummaryRowDto>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<IReadOnlyList<SalesFreeIssueSummaryRowDto>>> FreeIssueSummary(
-        [FromQuery] DateOnly from, [FromQuery] DateOnly to, CancellationToken ct)
-        => Ok(await _reports.FreeIssueSummaryAsync(from, to, ct));
+    [HttpPost("query")]
+    [ProducesResponseType(typeof(SalesReportQueryResponse), StatusCodes.Status200OK)]
+    public async Task<ActionResult<SalesReportQueryResponse>> Query([FromBody] SalesReportQueryRequest request, CancellationToken ct)
+    {
+        var rows = await _reports.QueryAsync(request.ReportType, request.From, request.To, request.ItemId, request.CustomerId, request.WarehouseId, ct);
+        return Ok(new SalesReportQueryResponse(request.ReportType, request.From, request.To, rows));
+    }
 }

Backend/ERPCore/Controllers/SalesSlipPromotionsController.cs

@@ -0,0 +1,22 @@
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+[Route("api/v1/sales-slips/{salesSlipId:int}/free-issue-suggestions")]
+public sealed class SalesSlipPromotionsController : ApiControllerBase
+{
+    private readonly ISalesPromotionSuggestionService _suggestions;
+
+    public SalesSlipPromotionsController(ISalesPromotionSuggestionService suggestions) => _suggestions = suggestions;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(SalesFreeIssueSuggestionDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<SalesFreeIssueSuggestionDto>> Get(int salesSlipId, CancellationToken ct)
+    {
+        var result = await _suggestions.GetFreeIssueSuggestionsAsync(salesSlipId, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+}

Backend/ERPCore/Controllers/SalesSlipsController.cs

@@ -34,6 +34,12 @@ public sealed class SalesSlipsController : ApiControllerBase
         return Ok(result.Value);
     }
 
+    [HttpGet("{salesSlipId:int}/posting-check")]
+    [ProducesResponseType(typeof(SalesSlipPostingCheckDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<SalesSlipPostingCheckDto>> PostingCheck(int salesSlipId, CancellationToken ct)
+        => Ok(await _slips.CheckPostingAsync(salesSlipId, ct));
+
     [HttpPost]
     [ProducesResponseType(typeof(SalesSlipDto), StatusCodes.Status201Created)]
     public async Task<ActionResult<SalesSlipDto>> Create([FromBody] CreateSalesSlipRequest request, CancellationToken ct)

Backend/ERPCore/Domain/Enums/SalesDiscountMode.cs

@@ -3,5 +3,5 @@ namespace ERPCore.Domain.Enums;
 public enum SalesDiscountMode
 {
     Percentage = 1,
-    FixedAmount = 2
+    Amount = 2
 }

Backend/ERPCore/Dtos/Sales/SalesInvoiceDtos.cs

@@ -24,6 +24,14 @@ public sealed record SalesInvoiceSummaryDto(
     string CustomerSnapshotName, int WarehouseId, SalesInvoiceType InvoiceType,
     SalesInvoiceStatus Status, SalesInvoiceTotalsDto Totals, DateTime CreatedAt);
 
+public sealed record SalesInvoicePostingIssueDto(
+    int SalesInvoiceLineId, int ItemId, string ItemSku, string ItemName, int WarehouseId,
+    decimal RequestedQty, decimal AvailableQty, decimal ShortQty, bool IsFreeIssue);
+
+public sealed record SalesInvoicePostingCheckDto(
+    int SalesInvoiceId, string InvoiceNo, SalesInvoiceStatus Status, bool CanPost,
+    IReadOnlyList<SalesInvoicePostingIssueDto> Issues);
+
 public sealed class CreateSalesInvoiceLineRequest
 {
     [Required] public int ItemId { get; set; }

Backend/ERPCore/Dtos/Sales/SalesPromotionSuggestionDtos.cs

@@ -0,0 +1,23 @@
+namespace ERPCore.Dtos.Sales;
+
+public sealed record SalesFreeIssueRewardOptionDto(
+    int ItemId,
+    string Sku,
+    string Name,
+    decimal? SalePrice);
+
+public sealed record SalesFreeIssueSuggestionLineDto(
+    int SalesSlipLineId,
+    int ItemId,
+    string ItemSku,
+    string ItemName,
+    decimal Qty,
+    decimal SuggestedFreeQty,
+    decimal TriggerQty,
+    IReadOnlyList<SalesFreeIssueRewardOptionDto> RewardOptions);
+
+public sealed record SalesFreeIssueSuggestionDto(
+    int SalesSlipId,
+    string SlipNo,
+    DateTime SlipDate,
+    IReadOnlyList<SalesFreeIssueSuggestionLineDto> Lines);

Backend/ERPCore/Dtos/Sales/SalesReportQueryDtos.cs

@@ -0,0 +1,21 @@
+namespace ERPCore.Dtos.Sales;
+
+public sealed record SalesReportDefinitionDto(
+    string Id,
+    string Name,
+    string Description,
+    IReadOnlyList<string> SupportedFilters);
+
+public sealed record SalesReportQueryRequest(
+    string ReportType,
+    DateOnly From,
+    DateOnly To,
+    int? ItemId = null,
+    int? CustomerId = null,
+    int? WarehouseId = null);
+
+public sealed record SalesReportQueryResponse(
+    string ReportType,
+    DateOnly From,
+    DateOnly To,
+    IReadOnlyList<object> Rows);

Backend/ERPCore/Dtos/Sales/SalesSlipDtos.cs

@@ -23,6 +23,25 @@ public sealed record SalesSlipSummaryDto(
     string CustomerSnapshotName, int WarehouseId, SalesSlipStatus Status,
     SalesSlipTotalsDto Totals, DateTime CreatedAt);
 
+public sealed record SalesSlipPostingIssueDto(
+    int SalesSlipLineId, int ItemId, string ItemSku, string ItemName, int WarehouseId,
+    decimal RequestedQty, decimal AvailableQty, decimal ShortQty, bool IsFreeIssue);
+
+public sealed record SalesSlipPostingCheckDto(
+    int SalesSlipId, string SlipNo, SalesSlipStatus Status, bool CanPost,
+    IReadOnlyList<SalesSlipPostingIssueDto> Issues);
+
+public sealed record FreeIssueSummaryDto(
+    int SalesSlipId, string SlipNo, SalesSlipStatus Status, DateTime CreatedAt,
+    int WarehouseId, string WarehouseName, int ItemId, string ItemSku, string ItemName,
+    int UomId, string UomName, decimal Qty, decimal FreeQty, string SchemeLabel);
+
+public sealed record FreeIssueDto(
+    int SalesSlipId, string SlipNo, DateTime SlipDate, SalesSlipStatus Status,
+    int CustomerId, string CustomerSnapshotName, int WarehouseId, string WarehouseName,
+    int CashierUserId, DateTime CreatedAt, DateTime? UpdatedAt, FreeIssueSummaryDto Summary,
+    IReadOnlyList<SalesSlipLineDto> Lines);
+
 public sealed class CreateSalesSlipLineRequest
 {
     [Required] public int ItemId { get; set; }

Backend/ERPCore/Infra/Persistence/DataSeeder.cs

@@ -1,4 +1,5 @@
 using ERPCore.Domain.Entities;
+using ERPCore.Domain;
 using ERPCore.Domain.Enums;
 using Microsoft.EntityFrameworkCore;
 
@@ -42,7 +43,11 @@ public static class DataSeeder
     {
         var dirty = await SeedReasonCodesAsync(db, ct);
         dirty |= await SeedItemTypesAsync(db, ct);
+        dirty |= await SeedCompanyProfileAsync(db, ct);
         dirty |= await SeedProductConfigAsync(db, ct);
+        dirty |= await SeedSalesMastersAsync(db, ct);
+        dirty |= await SeedSalesStockAsync(db, ct);
+        dirty |= await SeedSalesAsync(db, ct);
 
         if (dirty) await db.SaveChangesAsync(ct);
     }
@@ -99,4 +104,541 @@ public static class DataSeeder
         });
         return true;
     }
+
+    /// <summary>
+    /// Seeds a printable company profile with reasonable defaults for invoice headers.
+    /// These values are intentionally editable later through the API.
+    /// </summary>
+    private static async Task<bool> SeedCompanyProfileAsync(ErpDbContext db, CancellationToken ct)
+    {
+        if (await db.CompanyProfiles.AnyAsync(c => c.CompanyProfileId == CompanyProfile.SingletonId, ct)) return false;
+
+        db.CompanyProfiles.Add(new CompanyProfile
+        {
+            CompanyProfileId = CompanyProfile.SingletonId,
+            LegalName = "ERP Core Trading (Pvt) Ltd",
+            TradeName = "ERP Core Trading",
+            TaxRegistrationNo = "TAX-DEFAULT-001",
+            VatRegistrationNo = "VAT-DEFAULT-001",
+            AddressLine1 = "1 Demo Street",
+            City = "Colombo",
+            Country = "Sri Lanka",
+            Phone = "+94 11 000 0000",
+            Email = "accounts@example.com",
+            BankName = "Demo Bank",
+            BankBranch = "Colombo Main",
+            AccountName = "ERP Core Trading (Pvt) Ltd",
+            AccountNumber = "000123456789",
+            SwiftCode = "DEMO1234",
+            FooterNote = "Thank you for your business."
+        });
+        return true;
+    }
+
+    /// <summary>
+    /// Seeds the minimum catalog data required for the sales demo rows to exist.
+    /// These are safe additive rows and do not alter any existing data.
+    /// </summary>
+    private static async Task<bool> SeedSalesMastersAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var dirty = false;
+
+        dirty |= await SeedWarehousesAsync(db, ct);
+        dirty |= await SeedUomsAsync(db, ct);
+        dirty |= await SeedCategoriesAsync(db, ct);
+        dirty |= await SeedItemsAsync(db, ct);
+
+        return dirty;
+    }
+
+    /// <summary>
+    /// Seeds a simple on-hand FIFO layer for the demo sales item so the sample
+    /// invoices can be posted without immediately failing stock validation.
+    /// This keeps the stock-check and posting flows testable on a fresh database.
+    /// </summary>
+    private static async Task<bool> SeedSalesStockAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var warehouse = await db.Warehouses.AsNoTracking()
+            .OrderBy(w => w.WarehouseId)
+            .FirstOrDefaultAsync(ct);
+        var item = await db.Items.AsNoTracking()
+            .OrderBy(i => i.ItemId)
+            .FirstOrDefaultAsync(ct);
+        var secondItem = await db.Items.AsNoTracking()
+            .OrderByDescending(i => i.ItemId)
+            .FirstOrDefaultAsync(ct);
+
+        if (warehouse is null || item is null || secondItem is null)
+            return false;
+
+        var existing = await db.StockLayers.AnyAsync(
+            l => (l.ItemId == item.ItemId || l.ItemId == secondItem.ItemId) && l.WarehouseId == warehouse.WarehouseId && l.QtyRemaining > 0m,
+            ct);
+        if (existing) return false;
+
+        db.StockLayers.Add(new StockLayer
+        {
+            ItemId = item.ItemId,
+            WarehouseId = warehouse.WarehouseId,
+            QtyReceived = 100m,
+            QtyRemaining = 100m,
+            UnitCost = item.SalePrice.GetValueOrDefault() > 0m ? item.SalePrice.GetValueOrDefault() / 2m : 25m,
+            ReceiptDate = DateTime.UtcNow.AddDays(-7)
+        });
+        db.StockLayers.Add(new StockLayer
+        {
+            ItemId = secondItem.ItemId,
+            WarehouseId = warehouse.WarehouseId,
+            QtyReceived = 5m,
+            QtyRemaining = 5m,
+            UnitCost = secondItem.SalePrice.GetValueOrDefault() > 0m ? secondItem.SalePrice.GetValueOrDefault() / 2m : 15m,
+            ReceiptDate = DateTime.UtcNow.AddDays(-6)
+        });
+        return true;
+    }
+
+    private static async Task<bool> SeedWarehousesAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var existingCodes = await db.Warehouses.Select(w => w.Code).ToListAsync(ct);
+        var have = existingCodes.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        var seeds = new[]
+        {
+            new Warehouse { Code = "MAIN", Name = "Main Warehouse" },
+            new Warehouse { Code = "SHOP", Name = "Sales Counter" }
+        };
+
+        var toAdd = seeds.Where(w => !have.Contains(w.Code)).ToList();
+        if (toAdd.Count == 0) return false;
+
+        db.Warehouses.AddRange(toAdd);
+        return true;
+    }
+
+    private static async Task<bool> SeedUomsAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var existingNames = await db.Uoms.Select(u => u.Name).ToListAsync(ct);
+        var have = existingNames.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        var seeds = new[]
+        {
+            new Uom { Name = "PCS" },
+            new Uom { Name = "BOX" }
+        };
+
+        var toAdd = seeds.Where(u => !have.Contains(u.Name)).ToList();
+        if (toAdd.Count == 0) return false;
+
+        db.Uoms.AddRange(toAdd);
+        return true;
+    }
+
+    private static async Task<bool> SeedCategoriesAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var existingNames = await db.Categories.Select(c => c.Name).ToListAsync(ct);
+        var have = existingNames.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        var seeds = new[]
+        {
+            new Category { Name = "General Goods", Status = EntityStatus.Active, CreatedAt = DateTime.UtcNow },
+            new Category { Name = "Accessories", Status = EntityStatus.Active, CreatedAt = DateTime.UtcNow }
+        };
+
+        var toAdd = seeds.Where(c => !have.Contains(c.Name)).ToList();
+        if (toAdd.Count == 0) return false;
+
+        db.Categories.AddRange(toAdd);
+        return true;
+    }
+
+    private static async Task<bool> SeedItemsAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var existingSkus = await db.Items.Select(i => i.Sku).ToListAsync(ct);
+        var have = existingSkus.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        var category = await db.Categories.AsNoTracking()
+            .OrderBy(c => c.CategoryId)
+            .FirstOrDefaultAsync(ct);
+        var uom = await db.Uoms.AsNoTracking()
+            .OrderBy(u => u.UomId)
+            .FirstOrDefaultAsync(ct);
+
+        if (category is null || uom is null)
+            return false;
+
+        var now = DateTime.UtcNow;
+        var seeds = new[]
+        {
+            new Item
+            {
+                Sku = "SKU-DEMO-001",
+                Name = "Demo Item 1",
+                Description = "Seeded sample item for sales documents",
+                CategoryId = category.CategoryId,
+                BaseUomId = uom.UomId,
+                StockNature = StockNature.Stocked,
+                TrackingMode = TrackingMode.None,
+                SalePrice = 100m,
+                Status = EntityStatus.Active,
+                CreatedAt = now
+            },
+            new Item
+            {
+                Sku = "SKU-DEMO-002",
+                Name = "Demo Item 2",
+                Description = "Secondary seeded sample item for sales documents",
+                CategoryId = category.CategoryId,
+                BaseUomId = uom.UomId,
+                StockNature = StockNature.Stocked,
+                TrackingMode = TrackingMode.None,
+                SalePrice = 50m,
+                Status = EntityStatus.Active,
+                CreatedAt = now
+            }
+        };
+
+        var toAdd = seeds.Where(i => !have.Contains(i.Sku)).ToList();
+        if (toAdd.Count == 0) return false;
+
+        db.Items.AddRange(toAdd);
+        return true;
+    }
+
+    /// <summary>
+    /// Seeds the minimum sales bootstrap data needed for UI/backend development:
+    /// a couple of customer rows, current-year document counters, and a few draft
+    /// invoice/slip samples when the required master data already exists.
+    /// This intentionally never clears or rewrites any existing rows.
+    /// </summary>
+    private static async Task<bool> SeedSalesAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var dirty = false;
+
+        dirty |= await SeedSalesCustomersAsync(db, ct);
+        dirty |= await SeedSalesSequencesAsync(db, ct);
+        dirty |= await SeedSampleSalesDocsAsync(db, ct);
+
+        return dirty;
+    }
+
+    private static async Task<bool> SeedSalesCustomersAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var existingCodes = await db.Customers.Select(c => c.CustomerCode).ToListAsync(ct);
+        var have = existingCodes.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        var seeds = new[]
+        {
+            new Customer
+            {
+                CustomerCode = "CUST-WALKIN",
+                CustomerType = CustomerType.B2C,
+                Name = "Walk-in Customer",
+                DisplayName = "Walk-in Customer",
+                CreditLimit = 0m,
+                CreditDays = 0,
+                Status = EntityStatus.Active,
+                CreatedAt = DateTime.UtcNow
+            },
+            new Customer
+            {
+                CustomerCode = "CUST-DEMO",
+                CustomerType = CustomerType.B2B,
+                Name = "Demo Retail Ltd",
+                DisplayName = "Demo Retail Ltd",
+                Phone = "+94 11 000 0000",
+                Email = "sales@example.com",
+                AddressLine1 = "1 Demo Street",
+                City = "Colombo",
+                Country = "Sri Lanka",
+                TaxRegistrationNo = "VAT-DEMO-001",
+                CreditLimit = 250000m,
+                CreditDays = 30,
+                Status = EntityStatus.Active,
+                CreatedAt = DateTime.UtcNow
+            }
+        };
+
+        var toAdd = seeds.Where(c => !have.Contains(c.CustomerCode)).ToList();
+        if (toAdd.Count == 0) return false;
+
+        db.Customers.AddRange(toAdd);
+        return true;
+    }
+
+    private static async Task<bool> SeedSalesSequencesAsync(ErpDbContext db, CancellationToken ct)
+    {
+        var year = DateTime.UtcNow.Year;
+        var existing = await db.NumberSequences
+            .Where(s => s.Year == year && (s.DocType == DocumentTypes.SalesInvoice || s.DocType == DocumentTypes.SalesSlip))
+            .Select(s => s.DocType)
+            .ToListAsync(ct);
+        var have = existing.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        var seeds = new[]
+        {
+            new NumberSequence { DocType = DocumentTypes.SalesInvoice, Year = year, LastNumber = 0 },
+            new NumberSequence { DocType = DocumentTypes.SalesSlip, Year = year, LastNumber = 0 }
+        };
+
+        var toAdd = seeds.Where(s => !have.Contains(s.DocType)).ToList();
+        if (toAdd.Count == 0) return false;
+
+        db.NumberSequences.AddRange(toAdd);
+        return true;
+    }
+
+    private static async Task<bool> SeedSampleSalesDocsAsync(ErpDbContext db, CancellationToken ct)
+    {
+        if (await db.SalesInvoices.AnyAsync(ct) || await db.SalesSlips.AnyAsync(ct))
+            return false;
+
+        var customer = await db.Customers.AsNoTracking()
+            .OrderBy(c => c.CustomerId)
+            .FirstOrDefaultAsync(ct);
+        var warehouse = await db.Warehouses.AsNoTracking()
+            .OrderBy(w => w.WarehouseId)
+            .FirstOrDefaultAsync(ct);
+        var secondaryWarehouse = await db.Warehouses.AsNoTracking()
+            .OrderByDescending(w => w.WarehouseId)
+            .FirstOrDefaultAsync(ct);
+        var items = await db.Items.AsNoTracking()
+            .OrderBy(i => i.ItemId)
+            .Take(2)
+            .ToListAsync(ct);
+        var uom = await db.Uoms.AsNoTracking()
+            .OrderBy(u => u.UomId)
+            .FirstOrDefaultAsync(ct);
+        var user = await db.Users.AsNoTracking()
+            .OrderBy(u => u.UserId)
+            .FirstOrDefaultAsync(ct);
+
+        if (customer is null || warehouse is null || secondaryWarehouse is null || items.Count < 2 || uom is null || user is null)
+            return false;
+
+        var postableItem = items[0];
+        var shortageItem = items[1];
+        var today = DateTime.UtcNow.Date;
+        var createdAt = DateTime.UtcNow.AddDays(-1);
+
+        db.SalesInvoices.AddRange(
+            new SalesInvoice
+            {
+                InvoiceNo = $"SI-{today:yyyy}-00001",
+                InvoiceDate = today.AddDays(-2),
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.Name,
+                CustomerSnapshotTaxNo = customer.TaxRegistrationNo,
+                WarehouseId = warehouse.WarehouseId,
+                InvoiceType = SalesInvoiceType.B2C,
+                Status = SalesInvoiceStatus.Draft,
+                Subtotal = 200m,
+                DiscountTotal = 0m,
+                TaxTotal = 0m,
+                GrandTotal = 200m,
+                RoundOff = 0m,
+                NetPayable = 200m,
+                PaidAmount = 0m,
+                BalanceAmount = 200m,
+                CreatedBy = user.UserId,
+                CreatedAt = createdAt,
+                Lines =
+                [
+                    new SalesInvoiceLine
+                    {
+                        ItemId = postableItem.ItemId,
+                        Description = postableItem.Name,
+                        Qty = 2m,
+                        FreeQty = 0m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = 100m,
+                        BaseCost = 0m,
+                        PriceSource = "seed",
+                        DiscountMode = SalesDiscountMode.Percentage,
+                        DiscountPct = 0m,
+                        DiscountAmount = 0m,
+                        NetUnitPrice = 100m,
+                        LineTotal = 200m,
+                        TaxPct = 0m,
+                        TaxAmount = 0m,
+                        IsFreeIssue = false
+                    }
+                ]
+            },
+            new SalesInvoice
+            {
+                InvoiceNo = $"SI-{today:yyyy}-00002",
+                InvoiceDate = today.AddDays(-1),
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.Name,
+                CustomerSnapshotTaxNo = customer.TaxRegistrationNo,
+                WarehouseId = secondaryWarehouse.WarehouseId,
+                InvoiceType = SalesInvoiceType.B2B,
+                Status = SalesInvoiceStatus.Draft,
+                Subtotal = 300m,
+                DiscountTotal = 0m,
+                TaxTotal = 0m,
+                GrandTotal = 300m,
+                RoundOff = 0m,
+                NetPayable = 300m,
+                PaidAmount = 0m,
+                BalanceAmount = 300m,
+                CreatedBy = user.UserId,
+                CreatedAt = createdAt,
+                Lines =
+                [
+                    new SalesInvoiceLine
+                    {
+                        ItemId = shortageItem.ItemId,
+                        Description = shortageItem.Name,
+                        Qty = 6m,
+                        FreeQty = 0m,
+                        UomId = uom.UomId,
+                        WarehouseId = secondaryWarehouse.WarehouseId,
+                        UnitPrice = 50m,
+                        BaseCost = 0m,
+                        PriceSource = "seed",
+                        DiscountMode = SalesDiscountMode.Percentage,
+                        DiscountPct = 0m,
+                        DiscountAmount = 0m,
+                        NetUnitPrice = 50m,
+                        LineTotal = 300m,
+                        TaxPct = 0m,
+                        TaxAmount = 0m,
+                        IsFreeIssue = false
+                    }
+                ]
+            },
+            new SalesInvoice
+            {
+                InvoiceNo = $"SI-{today:yyyy}-00003",
+                InvoiceDate = today,
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.Name,
+                CustomerSnapshotTaxNo = customer.TaxRegistrationNo,
+                WarehouseId = warehouse.WarehouseId,
+                InvoiceType = SalesInvoiceType.B2C,
+                Status = SalesInvoiceStatus.Posted,
+                Subtotal = 100m,
+                DiscountTotal = 0m,
+                TaxTotal = 0m,
+                GrandTotal = 100m,
+                RoundOff = 0m,
+                NetPayable = 100m,
+                PaidAmount = 100m,
+                BalanceAmount = 0m,
+                CreatedBy = user.UserId,
+                CreatedAt = createdAt,
+                UpdatedAt = DateTime.UtcNow,
+                Lines =
+                [
+                    new SalesInvoiceLine
+                    {
+                        ItemId = postableItem.ItemId,
+                        Description = postableItem.Name,
+                        Qty = 1m,
+                        FreeQty = 0m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = 100m,
+                        BaseCost = 0m,
+                        PriceSource = "seed",
+                        DiscountMode = SalesDiscountMode.Percentage,
+                        DiscountPct = 0m,
+                        DiscountAmount = 0m,
+                        NetUnitPrice = 100m,
+                        LineTotal = 100m,
+                        TaxPct = 0m,
+                        TaxAmount = 0m,
+                        IsFreeIssue = false
+                    }
+                ]
+            }
+        );
+
+        db.SalesSlips.AddRange(
+            new SalesSlip
+            {
+                SlipNo = $"SSL-{today:yyyy}-00001",
+                SlipDate = today.AddDays(-2),
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.Name,
+                WarehouseId = warehouse.WarehouseId,
+                CashierUserId = user.UserId,
+                Status = SalesSlipStatus.Draft,
+                Subtotal = 50m,
+                DiscountTotal = 0m,
+                TaxTotal = 0m,
+                GrandTotal = 50m,
+                PaidAmount = 0m,
+                BalanceAmount = 50m,
+                CreatedAt = createdAt,
+                Lines =
+                [
+                    new SalesSlipLine
+                    {
+                        ItemId = postableItem.ItemId,
+                        Description = postableItem.Name,
+                        Qty = 1m,
+                        FreeQty = 0m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = 50m,
+                        BaseCost = 0m,
+                        PriceSource = "seed",
+                        DiscountMode = SalesDiscountMode.Percentage,
+                        DiscountPct = 0m,
+                        DiscountAmount = 0m,
+                        NetUnitPrice = 50m,
+                        LineTotal = 50m,
+                        TaxPct = 0m,
+                        TaxAmount = 0m,
+                        IsFreeIssue = false
+                    }
+                ]
+            },
+            new SalesSlip
+            {
+                SlipNo = $"SSL-{today:yyyy}-00002",
+                SlipDate = today.AddDays(-1),
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.Name,
+                WarehouseId = secondaryWarehouse.WarehouseId,
+                CashierUserId = user.UserId,
+                Status = SalesSlipStatus.Draft,
+                Subtotal = 150m,
+                DiscountTotal = 15m,
+                TaxTotal = 0m,
+                GrandTotal = 135m,
+                PaidAmount = 0m,
+                BalanceAmount = 135m,
+                CreatedAt = createdAt,
+                Lines =
+                [
+                    new SalesSlipLine
+                    {
+                        ItemId = shortageItem.ItemId,
+                        Description = shortageItem.Name,
+                        Qty = 3m,
+                        FreeQty = 0m,
+                        UomId = uom.UomId,
+                        WarehouseId = secondaryWarehouse.WarehouseId,
+                        UnitPrice = 50m,
+                        BaseCost = 0m,
+                        PriceSource = "seed",
+                        DiscountMode = SalesDiscountMode.Percentage,
+                        DiscountPct = 10m,
+                        DiscountAmount = 15m,
+                        NetUnitPrice = 45m,
+                        LineTotal = 135m,
+                        TaxPct = 0m,
+                        TaxAmount = 0m,
+                        IsFreeIssue = false
+                    }
+                ]
+            }
+        );
+
+        return true;
+    }
 }

Backend/ERPCore/Infra/Persistence/ErpDbContext.cs

@@ -15,6 +15,7 @@ namespace ERPCore.Infra.Persistence;
 public class ErpDbContext : DbContext
 {
     private readonly ICurrentUser _currentUser;
+    private bool _writingAuditLogs;
 
     public ErpDbContext(DbContextOptions<ErpDbContext> options, ICurrentUser currentUser) : base(options)
     {
@@ -35,6 +36,8 @@ public class ErpDbContext : DbContext
     public DbSet<Vendor> Vendors => Set<Vendor>();
     public DbSet<Warehouse> Warehouses => Set<Warehouse>();
     public DbSet<Bin> Bins => Set<Bin>();
+    /// <summary>Singleton business profile used by printable documents.</summary>
+    public DbSet<CompanyProfile> CompanyProfiles => Set<CompanyProfile>();
     /// <summary>Singleton row (FR-MD-11).</summary>
     public DbSet<ProductConfig> ProductConfig => Set<ProductConfig>();
 
@@ -185,24 +188,44 @@ public class ErpDbContext : DbContext
     // persists the logs without re-auditing them.
     public override async Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken ct = default)
     {
-        var pending = AuditScribe.Capture(ChangeTracker);
+        IReadOnlyList<PendingAudit> pending = _writingAuditLogs
+            ? Array.Empty<PendingAudit>()
+            : AuditScribe.Capture(ChangeTracker);
         var result = await base.SaveChangesAsync(acceptAllChangesOnSuccess, ct);
         if (pending.Count > 0)
         {
-            WriteAuditLogs(pending);
-            await base.SaveChangesAsync(acceptAllChangesOnSuccess, ct);
+            try
+            {
+                _writingAuditLogs = true;
+                WriteAuditLogs(pending);
+                await base.SaveChangesAsync(acceptAllChangesOnSuccess, ct);
+            }
+            finally
+            {
+                _writingAuditLogs = false;
+            }
         }
         return result;
     }
 
     public override int SaveChanges(bool acceptAllChangesOnSuccess)
     {
-        var pending = AuditScribe.Capture(ChangeTracker);
+        IReadOnlyList<PendingAudit> pending = _writingAuditLogs
+            ? Array.Empty<PendingAudit>()
+            : AuditScribe.Capture(ChangeTracker);
         var result = base.SaveChanges(acceptAllChangesOnSuccess);
         if (pending.Count > 0)
         {
-            WriteAuditLogs(pending);
-            base.SaveChanges(acceptAllChangesOnSuccess);
+            try
+            {
+                _writingAuditLogs = true;
+                WriteAuditLogs(pending);
+                base.SaveChanges(acceptAllChangesOnSuccess);
+            }
+            finally
+            {
+                _writingAuditLogs = false;
+            }
         }
         return result;
     }

Backend/ERPCore/Migrations/20260728053233_InitialCreate.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ERPCore.Migrations
+{
+    /// <inheritdoc />
+    public partial class InitialCreate : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+
+        }
+    }
+}

Backend/ERPCore/Migrations/20260801000000_AddCompanyProfile.Designer.cs

@@ -0,0 +1,23 @@
+// <auto-generated />
+using ERPCore.Infra.Persistence;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ERPCore.Migrations
+{
+    [DbContext(typeof(ErpDbContext))]
+    [Migration("20260801000000_AddCompanyProfile")]
+    partial class AddCompanyProfile
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+            // This designer is kept minimal because the repo does not regenerate migrations here.
+            // EF tooling only needs the migration metadata to exist; the active model snapshot
+            // is updated separately.
+        }
+    }
+}

Backend/ERPCore/Migrations/20260801000000_AddCompanyProfile.cs

@@ -0,0 +1,60 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ERPCore.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddCompanyProfile : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "company_profile",
+                columns: table => new
+                {
+                    CompanyProfileId = table.Column<int>(type: "integer", nullable: false),
+                    LegalName = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false),
+                    TradeName = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    LogoUrl = table.Column<string>(type: "character varying(500)", maxLength: 500, nullable: true),
+                    TaxRegistrationNo = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: true),
+                    VatRegistrationNo = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: true),
+                    AddressLine1 = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    AddressLine2 = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    City = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: true),
+                    Country = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: true),
+                    Phone = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: true),
+                    Email = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    BankName = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    BankBranch = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    AccountName = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    AccountNumber = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: true),
+                    SwiftCode = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: true),
+                    FooterNote = table.Column<string>(type: "character varying(500)", maxLength: 500, nullable: true),
+                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
+                    UpdatedBy = table.Column<int>(type: "integer", nullable: true),
+                    xmin = table.Column<uint>(type: "xid", rowVersion: true, nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_company_profile", x => x.CompanyProfileId);
+                    table.CheckConstraint("ck_company_profile_singleton", "\"CompanyProfileId\" = 1");
+                    table.ForeignKey(
+                        name: "FK_company_profile_users_UpdatedBy",
+                        column: x => x.UpdatedBy,
+                        principalTable: "users",
+                        principalColumn: "UserId",
+                        onDelete: ReferentialAction.Restrict);
+                });
+
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "company_profile");
+        }
+    }
+}

Backend/ERPCore/Program.cs

@@ -11,7 +11,6 @@ using ERPCore.Services;
 using ERPCore.Services.Interfaces;
 using ERPCore.Services.Auth;
 using ERPCore.Services.Hrm;
-using ERPCore.Services.Interfaces;
 using ERPCore.Services.Production;
 using ERPCore.Services.Stock;
 using ERPCore.System.Errors;
@@ -79,6 +78,7 @@ builder.Services.AddScoped<IUomService, UomService>();
 builder.Services.AddScoped<ICategoryService, CategoryService>();
 builder.Services.AddScoped<IBrandService, BrandService>();
 builder.Services.AddScoped<IItemTypeService, ItemTypeService>();
+builder.Services.AddScoped<ICompanyProfileService, CompanyProfileService>();
 builder.Services.AddScoped<IProductConfigService, ProductConfigService>();
 builder.Services.AddScoped<IVendorService, VendorService>();
 builder.Services.AddScoped<IWarehouseService, WarehouseService>();
@@ -103,6 +103,7 @@ builder.Services.AddScoped<IGrnService, GrnService>();
 builder.Services.AddScoped<ISalesPricingService, SalesPricingService>();
 builder.Services.AddScoped<ISalesInvoiceService, SalesInvoiceService>();
 builder.Services.AddScoped<ISalesSlipService, SalesSlipService>();
+builder.Services.AddScoped<ISalesPromotionSuggestionService, SalesPromotionSuggestionService>();
 builder.Services.AddScoped<ISalesReportService, SalesReportService>();
 
 // Stock transactions + reference data (docs/11 §5–6)
@@ -179,7 +180,15 @@ var app = builder.Build();
 using (var scope = app.Services.CreateScope())
 {
     var db = scope.ServiceProvider.GetRequiredService<ErpDbContext>();
-    await DataSeeder.SeedAsync(db);
+    await db.Database.MigrateAsync();
+    try
+    {
+        await DataSeeder.SeedAsync(db);
+    }
+    catch (Exception ex)
+    {
+        throw new InvalidOperationException("Database migration succeeded, but startup seeding failed.", ex);
+    }
 }
 
 app.UseSerilogRequestLogging();

Backend/ERPCore/Services/Interfaces/ICompanyProfileService.cs

@@ -0,0 +1,10 @@
+using ERPCore.Common.Http;
+using ERPCore.Dtos.Config;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ICompanyProfileService
+{
+    Task<ETagged<CompanyProfileDto>> GetAsync(CancellationToken ct = default);
+    Task<ETagged<CompanyProfileDto>> UpdateAsync(UpdateCompanyProfileRequest request, uint expectedRowVersion, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesInvoiceService.cs

@@ -9,6 +9,7 @@ public interface ISalesInvoiceService
 {
     Task<PagedResponse<SalesInvoiceSummaryDto>> ListAsync(PageQuery query, SalesInvoiceStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default);
     Task<ETagged<SalesInvoiceDto>?> GetAsync(int salesInvoiceId, CancellationToken ct = default);
+    Task<SalesInvoicePostingCheckDto> CheckPostingAsync(int salesInvoiceId, CancellationToken ct = default);
     Task<ETagged<SalesInvoiceDto>> CreateAsync(CreateSalesInvoiceRequest request, CancellationToken ct = default);
     Task<ETagged<SalesInvoiceDto>> UpdateAsync(int salesInvoiceId, UpdateSalesInvoiceRequest request, uint expectedRowVersion, CancellationToken ct = default);
     Task<SalesInvoiceDto> PostAsync(int salesInvoiceId, CancellationToken ct = default);

Backend/ERPCore/Services/Interfaces/ISalesPromotionSuggestionService.cs

@@ -0,0 +1,8 @@
+using ERPCore.Dtos.Sales;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesPromotionSuggestionService
+{
+    Task<SalesFreeIssueSuggestionDto?> GetFreeIssueSuggestionsAsync(int salesSlipId, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesReportService.cs

@@ -4,6 +4,9 @@ namespace ERPCore.Services.Interfaces;
 
 public interface ISalesReportService
 {
+    IReadOnlyList<SalesReportDefinitionDto> ListReports();
+    SalesReportDefinitionDto? GetReport(string reportId);
+    Task<IReadOnlyList<object>> QueryAsync(string reportType, DateOnly from, DateOnly to, int? itemId, int? customerId, int? warehouseId, CancellationToken ct = default);
     Task<IReadOnlyList<SalesDailySummaryRowDto>> DailySummaryAsync(DateOnly from, DateOnly to, CancellationToken ct = default);
     Task<IReadOnlyList<SalesItemSummaryRowDto>> ItemSummaryAsync(DateOnly from, DateOnly to, int? itemId, int? warehouseId, CancellationToken ct = default);
     Task<IReadOnlyList<SalesCustomerSummaryRowDto>> CustomerSummaryAsync(DateOnly from, DateOnly to, int? customerId, CancellationToken ct = default);

Backend/ERPCore/Services/Interfaces/ISalesSlipService.cs

@@ -9,6 +9,9 @@ public interface ISalesSlipService
 {
     Task<PagedResponse<SalesSlipSummaryDto>> ListAsync(PageQuery query, SalesSlipStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default);
     Task<ETagged<SalesSlipDto>?> GetAsync(int salesSlipId, CancellationToken ct = default);
+    Task<PagedResponse<FreeIssueSummaryDto>> ListFreeIssuesAsync(PageQuery query, SalesSlipStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default);
+    Task<ETagged<FreeIssueDto>?> GetFreeIssueAsync(int salesSlipId, CancellationToken ct = default);
+    Task<SalesSlipPostingCheckDto> CheckPostingAsync(int salesSlipId, CancellationToken ct = default);
     Task<ETagged<SalesSlipDto>> CreateAsync(CreateSalesSlipRequest request, CancellationToken ct = default);
     Task<ETagged<SalesSlipDto>> UpdateAsync(int salesSlipId, UpdateSalesSlipRequest request, uint expectedRowVersion, CancellationToken ct = default);
     Task<SalesSlipDto> PostAsync(int salesSlipId, CancellationToken ct = default);

Backend/ERPCore/Services/SalesInvoiceService.cs

@@ -69,6 +69,41 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         return invoice is null ? null : new ETagged<SalesInvoiceDto>(Map(invoice), invoice.RowVersion);
     }
 
+    public async Task<SalesInvoicePostingCheckDto> CheckPostingAsync(int salesInvoiceId, CancellationToken ct = default)
+    {
+        var invoice = await _invoices.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesInvoiceId == salesInvoiceId, ct)
+            ?? throw new NotFoundException($"Sales invoice {salesInvoiceId} was not found.");
+
+        if (invoice.Status != SalesInvoiceStatus.Draft)
+            return new SalesInvoicePostingCheckDto(invoice.SalesInvoiceId, invoice.InvoiceNo, invoice.Status, false, Array.Empty<SalesInvoicePostingIssueDto>());
+
+        var issues = new List<SalesInvoicePostingIssueDto>();
+        foreach (var line in invoice.Lines)
+        {
+            var requestedQty = line.Qty + line.FreeQty;
+            var available = await _fifo.GetOnHandAsync(line.ItemId, line.WarehouseId, ct);
+            if (available >= requestedQty) continue;
+
+            var item = await _items.Query().AsNoTracking()
+                .Where(x => x.ItemId == line.ItemId)
+                .Select(x => new { x.Sku, x.Name })
+                .FirstAsync(ct);
+            issues.Add(new SalesInvoicePostingIssueDto(
+                line.SalesInvoiceLineId,
+                line.ItemId,
+                item.Sku,
+                item.Name,
+                line.WarehouseId,
+                requestedQty,
+                available,
+                requestedQty - available,
+                line.IsFreeIssue));
+        }
+
+        return new SalesInvoicePostingCheckDto(invoice.SalesInvoiceId, invoice.InvoiceNo, invoice.Status, issues.Count == 0, issues);
+    }
+
     public async Task<ETagged<SalesInvoiceDto>> CreateAsync(CreateSalesInvoiceRequest request, CancellationToken ct = default)
     {
         await ValidateReferencesAsync(request.CustomerId, request.WarehouseId, request.Lines, ct);
@@ -228,7 +263,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
 
     private static decimal CalculateDiscount(decimal gross, SalesDiscountMode mode, decimal discountPct, decimal discountValue, decimal legacyDiscountAmount)
     {
-        var computed = mode == SalesDiscountMode.FixedAmount
+        var computed = mode == SalesDiscountMode.Amount
             ? discountValue
             : gross * (discountPct / 100m);
 

Backend/ERPCore/Services/SalesPromotionSuggestionService.cs

@@ -0,0 +1,74 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Sales;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesPromotionSuggestionService : ISalesPromotionSuggestionService
+{
+    private const decimal FreeIssueThreshold = 10m;
+
+    private readonly IRepository<SalesSlip> _slips;
+    private readonly IRepository<Item> _items;
+
+    public SalesPromotionSuggestionService(IRepository<SalesSlip> slips, IRepository<Item> items)
+    {
+        _slips = slips;
+        _items = items;
+    }
+
+    public async Task<SalesFreeIssueSuggestionDto?> GetFreeIssueSuggestionsAsync(int salesSlipId, CancellationToken ct = default)
+    {
+        var slip = await _slips.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct);
+
+        if (slip is null) return null;
+
+        var itemIds = slip.Lines.Select(x => x.ItemId).Distinct().ToList();
+        var candidateItems = await _items.Query().AsNoTracking()
+            .Where(x => itemIds.Contains(x.ItemId) && x.Status == EntityStatus.Active)
+            .ToListAsync(ct);
+
+        var byItemId = candidateItems.ToDictionary(x => x.ItemId);
+        var suggestions = new List<SalesFreeIssueSuggestionLineDto>();
+
+        foreach (var line in slip.Lines.Where(x => x.Qty >= FreeIssueThreshold))
+        {
+            if (!byItemId.TryGetValue(line.ItemId, out var item)) continue;
+
+            var freeQty = Math.Floor(line.Qty / FreeIssueThreshold);
+            if (freeQty <= 0m) continue;
+
+            var rewardOptions = new List<SalesFreeIssueRewardOptionDto>
+            {
+                new(item.ItemId, item.Sku, item.Name, item.SalePrice)
+            };
+
+            var alternates = await _items.Query().AsNoTracking()
+                .Where(x => x.Status == EntityStatus.Active && x.CategoryId == item.CategoryId && x.ItemId != item.ItemId)
+                .OrderBy(x => x.Name)
+                .Take(3)
+                .Select(x => new SalesFreeIssueRewardOptionDto(x.ItemId, x.Sku, x.Name, x.SalePrice))
+                .ToListAsync(ct);
+
+            rewardOptions.AddRange(alternates.Where(x => rewardOptions.All(r => r.ItemId != x.ItemId)));
+
+            suggestions.Add(new SalesFreeIssueSuggestionLineDto(
+                line.SalesSlipLineId,
+                item.ItemId,
+                item.Sku,
+                item.Name,
+                line.Qty,
+                freeQty,
+                FreeIssueThreshold,
+                rewardOptions));
+        }
+
+        return suggestions.Count == 0
+            ? new SalesFreeIssueSuggestionDto(slip.SalesSlipId, slip.SlipNo, slip.SlipDate, Array.Empty<SalesFreeIssueSuggestionLineDto>())
+            : new SalesFreeIssueSuggestionDto(slip.SalesSlipId, slip.SlipNo, slip.SlipDate, suggestions);
+    }
+}

Backend/ERPCore/Services/SalesReportService.cs

@@ -3,12 +3,23 @@ using ERPCore.Domain.Enums;
 using ERPCore.Dtos.Sales;
 using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Interfaces;
+using ERPCore.System.Errors;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
 
 public sealed class SalesReportService : ISalesReportService
 {
+    private static readonly SalesReportDefinitionDto[] ReportDefinitions =
+    [
+        new("daily-summary", "Daily Summary", "Aggregated sales by day across posted invoices and slips.", ["from", "to"]),
+        new("item-summary", "Item Summary", "Aggregated sales by item across posted invoices and slips.", ["from", "to", "itemId", "warehouseId"]),
+        new("customer-summary", "Customer Summary", "Aggregated sales by customer across posted invoices and slips.", ["from", "to", "customerId"]),
+        new("warehouse-summary", "Warehouse Summary", "Aggregated sales by warehouse across posted invoices and slips.", ["from", "to", "warehouseId"]),
+        new("discount-summary", "Discount Summary", "Documents with discounts applied.", ["from", "to"]),
+        new("free-issue-summary", "Free Issue Summary", "Lines with free quantities issued.", ["from", "to"])
+    ];
+
     private readonly IRepository<SalesInvoice> _invoices;
     private readonly IRepository<SalesSlip> _slips;
 
@@ -18,6 +29,54 @@ public sealed class SalesReportService : ISalesReportService
         _slips = slips;
     }
 
+    public IReadOnlyList<SalesReportDefinitionDto> ListReports() => ReportDefinitions;
+
+    public SalesReportDefinitionDto? GetReport(string reportId)
+    {
+        var normalized = reportId.Trim().ToLowerInvariant();
+        return ReportDefinitions.FirstOrDefault(r => r.Id == normalized);
+    }
+
+    public async Task<IReadOnlyList<object>> QueryAsync(string reportType, DateOnly from, DateOnly to, int? itemId, int? customerId, int? warehouseId, CancellationToken ct = default)
+    {
+        var normalized = reportType.Trim().ToLowerInvariant();
+        ValidateFilters(normalized, itemId, customerId, warehouseId);
+
+        return normalized switch
+        {
+            "daily" or "daily-summary" => (await DailySummaryAsync(from, to, ct)).Cast<object>().ToList(),
+            "item" or "item-summary" or "item-wise" => (await ItemSummaryAsync(from, to, itemId, warehouseId, ct)).Cast<object>().ToList(),
+            "customer" or "customer-summary" or "customer-wise" => (await CustomerSummaryAsync(from, to, customerId, ct)).Cast<object>().ToList(),
+            "warehouse" or "warehouse-summary" or "warehouse-wise" => (await WarehouseSummaryAsync(from, to, warehouseId, ct)).Cast<object>().ToList(),
+            "discount" or "discount-summary" => (await DiscountSummaryAsync(from, to, ct)).Cast<object>().ToList(),
+            "free-issue" or "free-issue-summary" => (await FreeIssueSummaryAsync(from, to, ct)).Cast<object>().ToList(),
+            _ => throw new DomainException("INVALID_REPORT_TYPE", $"Unsupported sales report type '{reportType}'.", 400)
+        };
+    }
+
+    private static void ValidateFilters(string reportType, int? itemId, int? customerId, int? warehouseId)
+    {
+        var allowed = reportType switch
+        {
+            "daily" or "daily-summary" => new FilterSet(false, false, false),
+            "item" or "item-summary" or "item-wise" => new FilterSet(true, false, true),
+            "customer" or "customer-summary" or "customer-wise" => new FilterSet(false, true, false),
+            "warehouse" or "warehouse-summary" or "warehouse-wise" => new FilterSet(false, false, true),
+            "discount" or "discount-summary" => new FilterSet(false, false, false),
+            "free-issue" or "free-issue-summary" => new FilterSet(false, false, false),
+            _ => throw new DomainException("INVALID_REPORT_TYPE", $"Unsupported sales report type '{reportType}'.", 400)
+        };
+
+        if (!allowed.Item && itemId is not null)
+            throw new DomainException("INVALID_REPORT_FILTER", $"Filter 'itemId' is not valid for report type '{reportType}'.", 400);
+        if (!allowed.Customer && customerId is not null)
+            throw new DomainException("INVALID_REPORT_FILTER", $"Filter 'customerId' is not valid for report type '{reportType}'.", 400);
+        if (!allowed.Warehouse && warehouseId is not null)
+            throw new DomainException("INVALID_REPORT_FILTER", $"Filter 'warehouseId' is not valid for report type '{reportType}'.", 400);
+    }
+
+    private readonly record struct FilterSet(bool Item, bool Customer, bool Warehouse);
+
     public async Task<IReadOnlyList<SalesDailySummaryRowDto>> DailySummaryAsync(DateOnly from, DateOnly to, CancellationToken ct = default)
     {
         var invoiceRows = await _invoices.Query().AsNoTracking()
@@ -72,42 +131,51 @@ public sealed class SalesReportService : ISalesReportService
 
     public async Task<IReadOnlyList<SalesItemSummaryRowDto>> ItemSummaryAsync(DateOnly from, DateOnly to, int? itemId, int? warehouseId, CancellationToken ct = default)
     {
-        var invoiceLines = _invoices.Query().AsNoTracking()
-            .Where(x => x.Status == SalesInvoiceStatus.Posted && x.InvoiceDate >= from.ToDateTime(TimeOnly.MinValue) && x.InvoiceDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue));
-        if (warehouseId is not null) invoiceLines = invoiceLines.Where(x => x.WarehouseId == warehouseId);
-        var invoiceQuery = invoiceLines.SelectMany(x => x.Lines.Select(l => new
-        {
-            l.ItemId,
-            l.Description,
-            l.Qty,
-            l.FreeQty,
-            Gross = l.Qty * l.UnitPrice,
-            l.DiscountAmount,
-            l.TaxAmount,
-            l.LineTotal,
-            l.WarehouseId
-        }));
-        if (itemId is not null) invoiceQuery = invoiceQuery.Where(x => x.ItemId == itemId);
+        var invoiceRows = await _invoices.Query().AsNoTracking()
+            .Where(x => x.Status == SalesInvoiceStatus.Posted && x.InvoiceDate >= from.ToDateTime(TimeOnly.MinValue) && x.InvoiceDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue))
+            .SelectMany(x => x.Lines.Select(l => new
+            {
+                l.ItemId,
+                l.Description,
+                l.Qty,
+                l.FreeQty,
+                Gross = l.Qty * l.UnitPrice,
+                l.DiscountAmount,
+                l.TaxAmount,
+                l.LineTotal,
+                x.WarehouseId
+            }))
+            .ToListAsync(ct);
 
-        var slipLines = _slips.Query().AsNoTracking()
-            .Where(x => x.Status == SalesSlipStatus.Posted && x.SlipDate >= from.ToDateTime(TimeOnly.MinValue) && x.SlipDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue));
-        if (warehouseId is not null) slipLines = slipLines.Where(x => x.WarehouseId == warehouseId);
-        var slipQuery = slipLines.SelectMany(x => x.Lines.Select(l => new
-        {
-            l.ItemId,
-            l.Description,
-            l.Qty,
-            l.FreeQty,
-            Gross = l.Qty * l.UnitPrice,
-            l.DiscountAmount,
-            l.TaxAmount,
-            l.LineTotal,
-            l.WarehouseId
-        }));
-        if (itemId is not null) slipQuery = slipQuery.Where(x => x.ItemId == itemId);
+        if (warehouseId is not null)
+            invoiceRows = invoiceRows.Where(x => x.WarehouseId == warehouseId).ToList();
+        if (itemId is not null)
+            invoiceRows = invoiceRows.Where(x => x.ItemId == itemId).ToList();
 
-        var rows = await invoiceQuery.Concat(slipQuery)
+        var slipRows = await _slips.Query().AsNoTracking()
+            .Where(x => x.Status == SalesSlipStatus.Posted && x.SlipDate >= from.ToDateTime(TimeOnly.MinValue) && x.SlipDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue))
+            .SelectMany(x => x.Lines.Select(l => new
+            {
+                l.ItemId,
+                l.Description,
+                l.Qty,
+                l.FreeQty,
+                Gross = l.Qty * l.UnitPrice,
+                l.DiscountAmount,
+                l.TaxAmount,
+                l.LineTotal,
+                x.WarehouseId
+            }))
+            .ToListAsync(ct);
+
+        if (warehouseId is not null)
+            slipRows = slipRows.Where(x => x.WarehouseId == warehouseId).ToList();
+        if (itemId is not null)
+            slipRows = slipRows.Where(x => x.ItemId == itemId).ToList();
+
+        return invoiceRows.Concat(slipRows)
             .GroupBy(x => new { x.ItemId, x.Description })
+            .OrderByDescending(g => g.Sum(x => x.LineTotal) + g.Sum(x => x.TaxAmount))
             .Select(g => new SalesItemSummaryRowDto(
                 g.Key.ItemId,
                 g.Key.Description,
@@ -116,11 +184,8 @@ public sealed class SalesReportService : ISalesReportService
                 g.Sum(x => x.Gross),
                 g.Sum(x => x.DiscountAmount),
                 g.Sum(x => x.TaxAmount),
-                g.Sum(x => x.LineTotal + x.TaxAmount)))
-            .OrderByDescending(x => x.NetAmount)
-            .ToListAsync(ct);
-
-        return rows;
+                g.Sum(x => x.LineTotal) + g.Sum(x => x.TaxAmount)))
+            .ToList();
     }
 
     public async Task<IReadOnlyList<SalesCustomerSummaryRowDto>> CustomerSummaryAsync(DateOnly from, DateOnly to, int? customerId, CancellationToken ct = default)

Backend/ERPCore/Services/SalesSlipService.cs

@@ -70,6 +70,66 @@ public sealed class SalesSlipService : ISalesSlipService
         return slip is null ? null : new ETagged<SalesSlipDto>(Map(slip), slip.RowVersion);
     }
 
+    public async Task<PagedResponse<FreeIssueSummaryDto>> ListFreeIssuesAsync(PageQuery query, SalesSlipStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default)
+    {
+        IQueryable<SalesSlip> q = _slips.Query().AsNoTracking().Include(x => x.Lines);
+        q = q.Where(x => x.Lines.Any(l => l.IsFreeIssue || l.FreeQty > 0m));
+        if (!string.IsNullOrWhiteSpace(query.Q))
+        {
+            var term = query.Q.Trim();
+            q = q.Where(x => EF.Functions.ILike(x.SlipNo, $"%{term}%") || EF.Functions.ILike(x.CustomerSnapshotName, $"%{term}%"));
+        }
+        if (status is not null) q = q.Where(x => x.Status == status);
+        if (customerId is not null) q = q.Where(x => x.CustomerId == customerId);
+        if (warehouseId is not null) q = q.Where(x => x.WarehouseId == warehouseId);
+
+        var total = await q.CountAsync(ct);
+        var rows = await q.OrderByDescending(x => x.SalesSlipId).Skip(query.Skip).Take(query.PageSize).ToListAsync(ct);
+        return PagedResponse<FreeIssueSummaryDto>.Create(rows.Select(MapFreeIssueSummary).ToList(), query.Page, query.PageSize, total);
+    }
+
+    public async Task<ETagged<FreeIssueDto>?> GetFreeIssueAsync(int salesSlipId, CancellationToken ct = default)
+    {
+        var slip = await _slips.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct);
+        return slip is null ? null : new ETagged<FreeIssueDto>(MapFreeIssue(slip), slip.RowVersion);
+    }
+
+    public async Task<SalesSlipPostingCheckDto> CheckPostingAsync(int salesSlipId, CancellationToken ct = default)
+    {
+        var slip = await _slips.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct)
+            ?? throw new NotFoundException($"Sales slip {salesSlipId} was not found.");
+
+        if (slip.Status != SalesSlipStatus.Draft)
+            return new SalesSlipPostingCheckDto(slip.SalesSlipId, slip.SlipNo, slip.Status, false, Array.Empty<SalesSlipPostingIssueDto>());
+
+        var issues = new List<SalesSlipPostingIssueDto>();
+        foreach (var line in slip.Lines)
+        {
+            var requestedQty = line.Qty + line.FreeQty;
+            var available = await _fifo.GetOnHandAsync(line.ItemId, line.WarehouseId, ct);
+            if (available >= requestedQty) continue;
+
+            var item = await _items.Query().AsNoTracking()
+                .Where(x => x.ItemId == line.ItemId)
+                .Select(x => new { x.Sku, x.Name })
+                .FirstAsync(ct);
+            issues.Add(new SalesSlipPostingIssueDto(
+                line.SalesSlipLineId,
+                line.ItemId,
+                item.Sku,
+                item.Name,
+                line.WarehouseId,
+                requestedQty,
+                available,
+                requestedQty - available,
+                line.IsFreeIssue));
+        }
+
+        return new SalesSlipPostingCheckDto(slip.SalesSlipId, slip.SlipNo, slip.Status, issues.Count == 0, issues);
+    }
+
     public async Task<ETagged<SalesSlipDto>> CreateAsync(CreateSalesSlipRequest request, CancellationToken ct = default)
     {
         await ValidateReferencesAsync(request.CustomerId, request.WarehouseId, request.CashierUserId, request.Lines, ct);
@@ -227,7 +287,7 @@ public sealed class SalesSlipService : ISalesSlipService
 
     private static decimal CalculateDiscount(decimal gross, SalesDiscountMode mode, decimal discountPct, decimal discountValue, decimal legacyDiscountAmount)
     {
-        var computed = mode == SalesDiscountMode.FixedAmount
+        var computed = mode == SalesDiscountMode.Amount
             ? discountValue
             : gross * (discountPct / 100m);
 
@@ -241,6 +301,57 @@ public sealed class SalesSlipService : ISalesSlipService
         x.SalesSlipId, x.SlipNo, x.SlipDate, x.CustomerId, x.CustomerSnapshotName, x.WarehouseId, x.Status,
         new SalesSlipTotalsDto(x.Subtotal, x.DiscountTotal, x.Lines.Sum(l => l.FreeQty), x.TaxTotal, x.GrandTotal, x.PaidAmount, x.BalanceAmount), x.CreatedAt);
 
+    private FreeIssueSummaryDto MapFreeIssueSummary(SalesSlip x)
+    {
+        var line = x.Lines.FirstOrDefault();
+        var item = line is null ? null : _items.Query().AsNoTracking()
+            .Where(i => i.ItemId == line.ItemId)
+            .Select(i => new { i.ItemId, i.Sku, i.Name, i.BaseUomId })
+            .FirstOrDefault();
+        var uom = line is null ? null : _uoms.Query().AsNoTracking()
+            .Where(u => u.UomId == line.UomId)
+            .Select(u => new { u.UomId, u.Name })
+            .FirstOrDefault();
+        var warehouse = _warehouses.Query().AsNoTracking()
+            .Where(w => w.WarehouseId == x.WarehouseId)
+            .Select(w => new { w.WarehouseId, w.Name })
+            .FirstOrDefault();
+        return new FreeIssueSummaryDto(
+            x.SalesSlipId,
+            x.SlipNo,
+            x.Status,
+            x.CreatedAt,
+            x.WarehouseId,
+            warehouse?.Name ?? $"Warehouse {x.WarehouseId}",
+            line?.ItemId ?? 0,
+            item?.Sku ?? $"SKU-{line?.ItemId ?? 0}",
+            item?.Name ?? line?.Description ?? "—",
+            line?.UomId ?? 0,
+            uom?.Name ?? $"UOM {line?.UomId ?? 0}",
+            line?.Qty ?? 0m,
+            line?.FreeQty ?? 0m,
+            line is null ? "No line" : $"Buy {line.Qty} Get {line.FreeQty}");
+    }
+
+    private FreeIssueDto MapFreeIssue(SalesSlip x)
+    {
+        var summary = MapFreeIssueSummary(x);
+        return new FreeIssueDto(
+            x.SalesSlipId,
+            x.SlipNo,
+            x.SlipDate,
+            x.Status,
+            x.CustomerId,
+            x.CustomerSnapshotName,
+            x.WarehouseId,
+            summary.WarehouseName,
+            x.CashierUserId,
+            x.CreatedAt,
+            x.UpdatedAt,
+            summary,
+            x.Lines.Select(l => new SalesSlipLineDto(l.SalesSlipLineId, l.ItemId, l.Description, l.Qty, l.FreeQty, l.UomId, l.WarehouseId, l.UnitPrice, l.BaseCost, l.PriceSource, l.DiscountPct, l.DiscountAmount, l.DiscountMode, l.NetUnitPrice, l.LineTotal, l.TaxPct, l.TaxAmount, l.IsFreeIssue, l.ParentLineId)).ToList());
+    }
+
     private static SalesSlipDto Map(SalesSlip x) => new(
         x.SalesSlipId, x.SlipNo, x.SlipDate, x.CustomerId, x.CustomerSnapshotName, x.WarehouseId, x.CashierUserId, x.Status, x.CreatedAt, x.UpdatedAt,
         new SalesSlipTotalsDto(x.Subtotal, x.DiscountTotal, x.Lines.Sum(l => l.FreeQty), x.TaxTotal, x.GrandTotal, x.PaidAmount, x.BalanceAmount),

Backend/PROGRESS.md

@@ -4,6 +4,11 @@ Legend: `[ ]` not started · `[~]` in progress · `[x]` done
 Spec: `docs/10-BACKEND-PHASE1.md` (model + rules) · `docs/11-BACKEND-PHASE1.md` (API)
 Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit** as the code. When ticking `[x]`, append a short note + any deviation.
 
+## 8. Sales
+- [x] Sales bootstrap data seeded locally for development: warehouses, UOMs, categories, items, customers, current-year `SI`/`SSL` sequences, plus sample invoice/slip headers and lines. Existing data is preserved.
+- [x] Sales report API consolidated into `GET /api/v1/reports/sales` (catalog), `GET /api/v1/reports/sales/{reportId}` (report metadata), and `POST /api/v1/reports/sales/query` (filtered data). Legacy per-report GET routes removed; invalid report/filter combinations now fail validation.
+- [x] Free-issue CRUD exposed as `api/v1/free-issues` as a thin alias over sales slips. Free issue remains a line-level `IsFreeIssue` / `FreeQty` behavior, not a separate table.
+
 ## 0. Bootstrap
 - [x] Solution + Web API project (`net10.0`), packages restored (00-CORE §5.4)
 - [x] Folder structure per 00-CORE §5.3

Frontend/PROGRESS.md

@@ -42,6 +42,13 @@ Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit**
 - [~] 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
 
+## 3.5 Sales screens
+- [~] Sales hub (`app/dashboard/sales`) — new module entry point linking to invoices, slips, free issues, and reports
+- [~] Sales invoices (`app/dashboard/sales/invoices`, `/new`, `/[id]`) — list/detail/create/edit routing wired to the real sales invoice API, including save/post/cancel on the detail page
+- [~] Sales slips (`app/dashboard/sales/slips`, `/new`, `/[id]`) — list/detail/create/edit routing wired to the real sales slip API, including save/post/cancel on the detail page
+- [~] Free issues (`app/dashboard/sales/free-issues`, `/new`, `/[id]`) — alias-only surface over sales slips for free-issue handling; edit/save/post/cancel stays on the slip screen
+- [~] Sales reports (`app/dashboard/sales/reports`, `/[reportId]`) — report catalog + report metadata view wired to `/reports/sales`
+
 ## 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, **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. **2026-07-22:** "Add line" now works in **PO mode** (off-PO items) + **"New item"** (opens `/dashboard/products/new` in a new tab) + **refresh** icon — see the 2026-07-22 entry.

Frontend/erp-system/app/dashboard/sales/free-issues/new/page.tsx

@@ -0,0 +1,493 @@
+"use client"
+
+import { useEffect, useState } from "react"
+import Link from "next/link"
+import { ArrowLeft, Pencil, Plus, Save, Trash2, X } from "lucide-react"
+
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { cn } from "@/lib/utils"
+import { errorMessage } from "@/lib/error-map"
+import { salesApi } from "@/lib/api/sales"
+import { customersApi } from "@/lib/api/customers"
+import { itemsApi } from "@/lib/api/items"
+import { uomsApi } from "@/lib/api/uoms"
+import { warehousesApi } from "@/lib/api/warehouses"
+import { usersApi } from "@/lib/api/users"
+import { toast } from "@/components/ui/toast"
+import { Customer } from "@/types/customers"
+import { ItemListItem, Uom, Warehouse } from "@/types/master-data"
+import { ManagedUser } from "@/types/users"
+import { CreateSalesSlipLineRequest, CreateSalesSlipRequest } from "@/types/sales"
+
+type Line = CreateSalesSlipLineRequest & { key: string }
+
+type FreeIssueRow = {
+  salesSlipId: number
+  slipNo: string
+  status: string
+  etag: string
+  warehouseName: string
+  itemName: string
+  itemSku: string
+  uomName: string
+  qty: number
+  freeQty: number
+}
+
+const blankLine = (key: string): Line => ({
+  key,
+  itemId: 0,
+  uomId: 0,
+  warehouseId: 0,
+  qty: 1,
+  freeQty: 0,
+  allowManualPriceOverride: true,
+  discountMode: "Percentage",
+  discountPct: 0,
+  discountAmount: 0,
+  discountValue: 0,
+  taxPct: 0,
+  isFreeIssue: false,
+  parentLineId: null,
+})
+
+export default function NewFreeIssuePage() {
+  const [customers, setCustomers] = useState<Customer[]>([])
+  const [items, setItems] = useState<ItemListItem[]>([])
+  const [uoms, setUoms] = useState<Uom[]>([])
+  const [warehouses, setWarehouses] = useState<Warehouse[]>([])
+  const [users, setUsers] = useState<ManagedUser[]>([])
+  const [customerId, setCustomerId] = useState<number | null>(null)
+  const [warehouseId, setWarehouseId] = useState<number | null>(null)
+  const [cashierUserId, setCashierUserId] = useState<number | null>(null)
+  const [lines, setLines] = useState<Line[]>([blankLine("line-1")])
+  const [rows, setRows] = useState<FreeIssueRow[]>([])
+  const [editingRowId, setEditingRowId] = useState<number | null>(null)
+  const [editingLines, setEditingLines] = useState<Line[]>([])
+  const [loading, setLoading] = useState(true)
+  const [saving, setSaving] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+
+  async function refreshRows() {
+    const list = await salesApi.listFreeIssues({ pageSize: 50 })
+    const details = await Promise.all(
+      list.items.map(async (summary) => {
+        const detail = await salesApi.getFreeIssue(summary.salesSlipId)
+        const firstLine = detail.data.lines[0]
+        const item = items.find((x) => x.itemId === firstLine?.itemId)
+        const uom = uoms.find((x) => x.uomId === firstLine?.uomId)
+        const warehouse = warehouses.find((x) => x.warehouseId === detail.data.warehouseId)
+        return {
+          salesSlipId: detail.data.salesSlipId,
+          slipNo: detail.data.slipNo,
+          status: detail.data.status,
+          etag: detail.etag ?? "",
+          warehouseName: warehouse?.name ?? `Warehouse ${detail.data.warehouseId}`,
+          itemName: item?.name ?? firstLine?.description ?? "—",
+          itemSku: item?.sku ?? `SKU-${firstLine?.itemId ?? 0}`,
+          uomName: uom?.name ?? `UOM ${firstLine?.uomId ?? 0}`,
+          qty: firstLine?.qty ?? 0,
+          freeQty: firstLine?.freeQty ?? 0,
+        } satisfies FreeIssueRow
+      }),
+    )
+    setRows(details.filter((row) => row.status !== "Cancelled"))
+  }
+
+  useEffect(() => {
+    Promise.all([
+      customersApi.list({ pageSize: 200 }),
+      itemsApi.list({ pageSize: 200 }),
+      uomsApi.list({ pageSize: 200 }),
+      warehousesApi.list({ pageSize: 200 }),
+      usersApi.list({ pageSize: 200 }),
+    ])
+      .then(async ([cust, itemRes, uomRes, whRes, userRes]) => {
+        setCustomers(cust.items)
+        setItems(itemRes.items)
+        setUoms(uomRes.items)
+        setWarehouses(whRes.items)
+        setUsers(userRes.items)
+        setCustomerId(cust.items[0]?.customerId ?? null)
+        setWarehouseId(whRes.items[0]?.warehouseId ?? null)
+        setCashierUserId(userRes.items[0]?.userId ?? null)
+        setLines([
+          {
+            ...blankLine("line-1"),
+            itemId: itemRes.items[0]?.itemId ?? 0,
+            uomId: itemRes.items[0]?.baseUomId ?? uomRes.items[0]?.uomId ?? 0,
+            warehouseId: whRes.items[0]?.warehouseId ?? 0,
+          },
+        ])
+        await refreshRows()
+      })
+      .catch((err) => setError(errorMessage(err)))
+      .finally(() => setLoading(false))
+  }, [])
+
+  function updateLine(key: string, patch: Partial<Line>) {
+    setLines((prev) => prev.map((line) => (line.key === key ? { ...line, ...patch } : line)))
+  }
+
+  function updateEditingLine(key: string, patch: Partial<Line>) {
+    setEditingLines((prev) => prev.map((line) => (line.key === key ? { ...line, ...patch } : line)))
+  }
+
+  function addLine() {
+    setLines((prev) => [...prev, blankLine(`line-${Date.now()}`)])
+  }
+
+  function removeLine(key: string) {
+    setLines((prev) => (prev.length === 1 ? prev : prev.filter((line) => line.key !== key)))
+  }
+
+  function selectItem(key: string, itemId: number) {
+    const item = items.find((candidate) => candidate.itemId === itemId)
+    updateLine(key, { itemId, uomId: item?.baseUomId ?? 0 })
+  }
+
+  function selectEditingItem(key: string, itemId: number) {
+    const item = items.find((candidate) => candidate.itemId === itemId)
+    updateEditingLine(key, { itemId, uomId: item?.baseUomId ?? 0 })
+  }
+
+  async function submit() {
+    const activeLines = editingRowId ? editingLines : lines
+    if (!customerId || !warehouseId || !cashierUserId) return setError("Select customer, warehouse, and cashier.")
+    if (activeLines.some((line) => !line.itemId)) return setError("Select an item for every line.")
+    if (activeLines.some((line) => !line.uomId)) return setError("Select a valid UOM for every line.")
+    if (activeLines.some((line) => !line.warehouseId)) return setError("Select a warehouse for every line.")
+
+    setSaving(true)
+    setError(null)
+    try {
+      const payload: CreateSalesSlipRequest = {
+        customerId,
+        warehouseId,
+        cashierUserId,
+        lines: activeLines.map((line) => ({
+          itemId: Number(line.itemId),
+          uomId: Number(line.uomId),
+          warehouseId: Number(line.warehouseId),
+          qty: Number(line.qty),
+          freeQty: Number(line.freeQty),
+          unitPrice: line.unitPrice === null ? null : Number(line.unitPrice),
+          allowManualPriceOverride: line.allowManualPriceOverride,
+          discountMode: line.discountMode,
+          discountPct: Number(line.discountPct),
+          discountAmount: Number(line.discountAmount),
+          discountValue: Number(line.discountValue),
+          taxPct: Number(line.taxPct),
+          isFreeIssue: line.isFreeIssue,
+          parentLineId: line.parentLineId || null,
+        })),
+      }
+
+      if (editingRowId) {
+        const latest = await salesApi.getFreeIssue(editingRowId)
+        await salesApi.updateFreeIssue(editingRowId, payload, latest.etag)
+        toast.success("Free issue updated")
+        setEditingRowId(null)
+        setEditingLines([])
+      } else {
+        const created = await salesApi.createFreeIssue(payload)
+        toast.success("Free issue created", created.data.slipNo)
+      }
+
+      setLines([blankLine("line-1")])
+      await refreshRows()
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  async function startEdit(row: FreeIssueRow) {
+    try {
+      const detail = await salesApi.getFreeIssue(row.salesSlipId)
+      const detailLine = detail.data.lines[0]
+      setEditingRowId(row.salesSlipId)
+      setCustomerId(detail.data.customerId)
+      setWarehouseId(detail.data.warehouseId)
+      setCashierUserId(detail.data.cashierUserId)
+      setEditingLines([
+        {
+          key: "edit-line-1",
+          itemId: detailLine?.itemId ?? 0,
+          uomId: detailLine?.uomId ?? 0,
+          warehouseId: detailLine?.warehouseId ?? detail.data.warehouseId,
+          qty: detailLine?.qty ?? 1,
+          freeQty: detailLine?.freeQty ?? 0,
+          unitPrice: detailLine?.unitPrice ?? null,
+          allowManualPriceOverride: true,
+          discountMode: detailLine?.discountMode ?? "Percentage",
+          discountPct: detailLine?.discountPct ?? 0,
+          discountAmount: detailLine?.discountAmount ?? 0,
+          discountValue: 0,
+          taxPct: detailLine?.taxPct ?? 0,
+          isFreeIssue: detailLine?.isFreeIssue ?? false,
+          parentLineId: detailLine?.parentLineId ?? null,
+        },
+      ])
+    } catch (err) {
+      setError(errorMessage(err))
+    }
+  }
+
+  function cancelEdit() {
+    setEditingRowId(null)
+    setEditingLines([])
+  }
+
+  async function deleteRow(row: FreeIssueRow) {
+    if (row.status !== "Draft") return
+    try {
+      await salesApi.cancelFreeIssue(row.salesSlipId)
+      toast.success("Free issue cancelled", row.slipNo)
+      if (editingRowId === row.salesSlipId) cancelEdit()
+      await refreshRows()
+    } catch (err) {
+      setError(errorMessage(err))
+    }
+  }
+
+  if (loading) {
+    return <div className="rounded-2xl border border-border bg-card p-8 text-muted-foreground shadow-[var(--shadow-panel)]">Loading masters...</div>
+  }
+
+  const activeLines = editingRowId ? editingLines : lines
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div className="flex items-center gap-3">
+          <Link href="/dashboard/sales" className={cn(buttonVariants({ variant: "outline", size: "icon" }))}>
+            <ArrowLeft className="size-4" />
+          </Link>
+          <div>
+            <h1 className="text-2xl font-bold text-foreground">Free Issues</h1>
+            <p className="text-base text-muted-foreground">Create and manage free-issue sales slips from the backend.</p>
+          </div>
+        </div>
+        <Button size="sm" onClick={submit} disabled={saving}>
+          <Save className="size-4" /> {saving ? "Saving..." : editingRowId ? "Update free issue" : "Create free issue"}
+        </Button>
+      </div>
+
+      {error ? <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div> : null}
+
+      {editingRowId ? (
+        <section className="rounded-2xl border border-sky-200 bg-sky-50 shadow-[var(--shadow-panel)]">
+          <div className="flex items-center justify-between border-b border-sky-200 px-4 py-3">
+            <h2 className="text-sm font-semibold text-sky-900">Inline edit free issue</h2>
+            <Button type="button" variant="outline" size="sm" onClick={cancelEdit}>
+              <X className="size-4" /> Cancel edit
+            </Button>
+          </div>
+          <div className="overflow-x-auto">
+            <Table className="text-sm">
+              <TableHeader>
+                <TableRow>
+                  <TableHead className="h-12 px-4 text-sm">ID</TableHead>
+                  <TableHead className="h-12 px-4 text-sm">Item</TableHead>
+                  <TableHead className="h-12 px-4 text-sm">UOM</TableHead>
+                  <TableHead className="h-12 px-4 text-sm text-right">Qty</TableHead>
+                  <TableHead className="h-12 px-4 text-sm text-right">Free</TableHead>
+                  <TableHead className="h-12 px-4 text-sm" />
+                </TableRow>
+              </TableHeader>
+              <TableBody>
+                {activeLines.map((line, idx) => (
+                  <TableRow key={line.key} className="align-middle">
+                    <TableCell className="px-4 py-2 text-xs text-muted-foreground">{idx + 1}</TableCell>
+                    <TableCell className="px-4 py-2 min-w-80">
+                      <Select value={line.itemId ? String(line.itemId) : ""} onValueChange={(v) => selectEditingItem(line.key, Number(v))}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="Select item" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {items.map((candidate) => (
+                            <SelectItem key={candidate.itemId} value={String(candidate.itemId)}>
+                              {candidate.sku} - {candidate.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2 min-w-44">
+                      <Select value={line.uomId ? String(line.uomId) : ""} onValueChange={(v) => updateEditingLine(line.key, { uomId: Number(v) })}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="UOM" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {uoms.map((u) => (
+                            <SelectItem key={u.uomId} value={String(u.uomId)}>
+                              {u.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input type="number" min="0" step="1" value={line.qty} onChange={(e) => updateEditingLine(line.key, { qty: Number(e.target.value) })} className="h-9 w-24 text-right font-mono text-sm tabular-nums" />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input type="number" min="0" step="1" value={line.freeQty} onChange={(e) => updateEditingLine(line.key, { freeQty: Number(e.target.value) })} className="h-9 w-24 text-right font-mono text-sm tabular-nums" />
+                    </TableCell>
+                    <TableCell className="px-4 py-2 text-right text-xs text-muted-foreground">editing</TableCell>
+                  </TableRow>
+                ))}
+              </TableBody>
+            </Table>
+          </div>
+        </section>
+      ) : (
+        <section className="rounded-2xl border border-border bg-card shadow-[var(--shadow-panel)]">
+          <div className="flex items-center justify-between border-b border-border px-4 py-3">
+            <h2 className="text-sm font-semibold">Free issue lines</h2>
+            <Button type="button" variant="outline" size="sm" onClick={addLine}>
+              <Plus className="size-4" /> Add line
+            </Button>
+          </div>
+          <div className="overflow-x-auto">
+            <Table className="text-sm">
+              <TableHeader>
+                <TableRow>
+                  <TableHead className="h-12 px-4 text-sm">ID</TableHead>
+                  <TableHead className="h-12 px-4 text-sm">Item</TableHead>
+                  <TableHead className="h-12 px-4 text-sm">UOM</TableHead>
+                  <TableHead className="h-12 px-4 text-sm text-right">Qty</TableHead>
+                  <TableHead className="h-12 px-4 text-sm text-right">Free</TableHead>
+                  <TableHead className="h-12 px-4 text-sm" />
+                </TableRow>
+              </TableHeader>
+              <TableBody>
+                {lines.map((line, idx) => (
+                  <TableRow key={line.key} className="align-middle">
+                    <TableCell className="px-4 py-2 text-xs text-muted-foreground">{idx + 1}</TableCell>
+                    <TableCell className="px-4 py-2 min-w-80">
+                      <Select value={line.itemId ? String(line.itemId) : ""} onValueChange={(v) => selectItem(line.key, Number(v))}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="Select item" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {items.map((candidate) => (
+                            <SelectItem key={candidate.itemId} value={String(candidate.itemId)}>
+                              {candidate.sku} - {candidate.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2 min-w-44">
+                      <Select value={line.uomId ? String(line.uomId) : ""} onValueChange={(v) => updateLine(line.key, { uomId: Number(v) })}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="UOM" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {uoms.map((u) => (
+                            <SelectItem key={u.uomId} value={String(u.uomId)}>
+                              {u.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input type="number" min="0" step="1" value={line.qty} onChange={(e) => updateLine(line.key, { qty: Number(e.target.value) })} className="h-9 w-24 text-right font-mono text-sm tabular-nums" />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input type="number" min="0" step="1" value={line.freeQty} onChange={(e) => updateLine(line.key, { freeQty: Number(e.target.value) })} className="h-9 w-24 text-right font-mono text-sm tabular-nums" />
+                    </TableCell>
+                    <TableCell className="px-4 py-2 text-right">
+                      <Button variant="ghost" size="icon" className="size-8 text-muted-foreground" onClick={() => removeLine(line.key)} disabled={lines.length === 1}>
+                        <Trash2 className="size-4" />
+                      </Button>
+                    </TableCell>
+                  </TableRow>
+                ))}
+              </TableBody>
+            </Table>
+          </div>
+        </section>
+      )}
+
+      <section className="rounded-2xl border border-border bg-card p-4 shadow-[var(--shadow-panel)]">
+        <div className="flex items-center justify-between">
+          <div>
+            <h3 className="text-sm font-semibold">Created free issues</h3>
+            <p className="mt-1 text-xs text-muted-foreground">Persisted backend records with draft-only cancellation.</p>
+          </div>
+          <Button variant="outline" size="sm" onClick={refreshRows}>
+            Refresh
+          </Button>
+        </div>
+        <div className="mt-3 overflow-x-auto">
+          <Table className="text-sm">
+            <TableHeader>
+              <TableRow>
+                <TableHead className="h-12 px-4 text-sm">Promotion</TableHead>
+                <TableHead className="h-12 px-4 text-sm">Warehouse</TableHead>
+                <TableHead className="h-12 px-4 text-sm">Product</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Qty</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Free</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Actions</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {rows.length > 0 ? (
+                rows.map((row) => (
+                  <TableRow key={row.salesSlipId} className="hover:bg-muted/40">
+                    <TableCell className="px-4 py-3.5">
+                      <div className="font-medium">Buy {row.qty} Get {row.freeQty || 0}</div>
+                      <div className="text-xs text-muted-foreground">{row.slipNo}</div>
+                    </TableCell>
+                    <TableCell className="px-4 py-3.5">{row.warehouseName}</TableCell>
+                    <TableCell className="px-4 py-3.5 min-w-80">
+                      <div className="font-medium">{row.itemName}</div>
+                      <div className="text-xs text-muted-foreground">{row.itemSku} · {row.uomName}</div>
+                    </TableCell>
+                    <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums">{row.qty}</TableCell>
+                    <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums">{row.freeQty}</TableCell>
+                    <TableCell className="px-4 py-3.5">
+                      <div className="flex justify-end gap-1.5">
+                        <button
+                          type="button"
+                          onClick={() => startEdit(row)}
+                          className="inline-flex h-7 items-center rounded-full border border-sky-200 bg-sky-50 px-2 text-xs text-sky-700 hover:bg-sky-100 hover:text-sky-800"
+                        >
+                          <Pencil className="mr-1 size-3.5" />
+                          Edit
+                        </button>
+                        {row.status === "Draft" ? (
+                          <button
+                            type="button"
+                            onClick={() => deleteRow(row)}
+                            className="inline-flex h-7 items-center rounded-full border border-rose-200 bg-rose-50 px-2 text-xs text-rose-700 hover:bg-rose-100 hover:text-rose-800"
+                          >
+                            <Trash2 className="mr-1 size-3.5" />
+                            Delete
+                          </button>
+                        ) : null}
+                      </div>
+                    </TableCell>
+                  </TableRow>
+                ))
+              ) : (
+                <TableRow>
+                  <TableCell colSpan={6} className="px-4 py-8 text-center text-sm text-muted-foreground">
+                    No free issues created yet.
+                  </TableCell>
+                </TableRow>
+              )}
+            </TableBody>
+          </Table>
+        </div>
+      </section>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/free-issues/page.tsx

@@ -0,0 +1,3 @@
+"use client"
+
+export { default } from "./new/page"

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

@@ -0,0 +1,605 @@
+"use client"
+
+import { use, useEffect, useMemo, useState } from "react"
+import Link from "next/link"
+import { useRouter } from "next/navigation"
+import { ArrowLeft, Minus, Plus, Printer, Save, Send, X } from "lucide-react"
+
+import { companyApi } from "@/lib/api/company"
+import { salesApi } from "@/lib/api/sales"
+import { customersApi } from "@/lib/api/customers"
+import { itemsApi } from "@/lib/api/items"
+import { uomsApi } from "@/lib/api/uoms"
+import { warehousesApi } from "@/lib/api/warehouses"
+import { errorMessage } from "@/lib/error-map"
+import { cn } from "@/lib/utils"
+import { getSuggestedUnitPrice } from "@/lib/sales-line-utils"
+import { CompanyProfile } from "@/types/company"
+import { Customer } from "@/types/customers"
+import { ItemListItem, Uom, Warehouse } from "@/types/master-data"
+import { CreateSalesInvoiceLineRequest, SalesInvoice, SalesInvoicePostingCheck, SalesInvoiceStatus, SalesInvoiceType } from "@/types/sales"
+import { toast } from "@/components/ui/toast"
+import { Label } from "@/components/ui/label"
+
+type Line = CreateSalesInvoiceLineRequest & { key: string }
+
+const money = new Intl.NumberFormat("en-LK", {
+  style: "currency",
+  currency: "LKR",
+  minimumFractionDigits: 2,
+})
+
+const blankLine = (key: string): Line => ({
+  key,
+  itemId: 0,
+  uomId: 0,
+  warehouseId: 0,
+  qty: 1,
+  freeQty: 0,
+  unitPrice: null,
+  allowManualPriceOverride: true,
+  discountMode: "Percentage",
+  discountPct: 0,
+  discountAmount: 0,
+  discountValue: 0,
+  taxPct: 0,
+  isFreeIssue: false,
+  parentLineId: null,
+})
+
+function statusClass(status: SalesInvoiceStatus) {
+  switch (status) {
+    case "Draft":
+      return "border-amber-200 bg-amber-50 text-amber-800"
+    case "Posted":
+      return "border-emerald-200 bg-emerald-50 text-emerald-800"
+    case "Cancelled":
+      return "border-rose-200 bg-rose-50 text-rose-800"
+  }
+}
+
+export default function SalesInvoiceDetailPage({ params }: { params: Promise<{ id: string }> }) {
+  const router = useRouter()
+  const resolvedParams = use(params)
+  const invoiceId = Number(resolvedParams.id)
+
+  const [invoice, setInvoice] = useState<SalesInvoice | null>(null)
+  const [company, setCompany] = useState<CompanyProfile | null>(null)
+  const [customers, setCustomers] = useState<Customer[]>([])
+  const [items, setItems] = useState<ItemListItem[]>([])
+  const [uoms, setUoms] = useState<Uom[]>([])
+  const [warehouses, setWarehouses] = useState<Warehouse[]>([])
+  const [lines, setLines] = useState<Line[]>([blankLine("line-1")])
+  const [customerId, setCustomerId] = useState<number | null>(null)
+  const [warehouseId, setWarehouseId] = useState<number | null>(null)
+  const [invoiceType, setInvoiceType] = useState<SalesInvoiceType>("B2C")
+  const [etag, setEtag] = useState<string | null>(null)
+  const [postingCheck, setPostingCheck] = useState<SalesInvoicePostingCheck | null>(null)
+  const [error, setError] = useState<string | null>(null)
+  const [saving, setSaving] = useState(false)
+  const [busy, setBusy] = useState<"post" | "cancel" | null>(null)
+
+  useEffect(() => {
+    if (!Number.isFinite(invoiceId)) {
+      setError(`Invalid invoice id '${resolvedParams.id}'.`)
+      return
+    }
+
+    Promise.all([
+      companyApi.getProfile(),
+      customersApi.list({ pageSize: 200 }),
+      itemsApi.list({ pageSize: 200 }),
+      uomsApi.list({ pageSize: 200 }),
+      warehousesApi.list({ pageSize: 200 }),
+      salesApi.getInvoice(invoiceId),
+    ])
+      .then(([companyRes, customerRes, itemRes, uomRes, warehouseRes, doc]) => {
+        setCompany(companyRes.data)
+        setCustomers(customerRes.items)
+        setItems(itemRes.items)
+        setUoms(uomRes.items)
+        setWarehouses(warehouseRes.items)
+        setInvoice(doc.data)
+        setEtag(doc.etag)
+        setCustomerId(doc.data.customerId)
+        setWarehouseId(doc.data.warehouseId)
+        setInvoiceType(doc.data.invoiceType)
+        setLines(
+          doc.data.lines.map((line) => ({
+            key: String(line.salesInvoiceLineId),
+            itemId: line.itemId,
+            uomId: line.uomId,
+            warehouseId: line.warehouseId,
+            qty: line.qty,
+            freeQty: line.freeQty,
+            unitPrice: line.unitPrice,
+            allowManualPriceOverride: true,
+            discountMode: line.discountMode,
+            discountPct: line.discountPct,
+            discountAmount: line.discountAmount,
+            discountValue: 0,
+            taxPct: line.taxPct,
+            isFreeIssue: line.isFreeIssue,
+            parentLineId: line.parentLineId,
+          }))
+        )
+      })
+      .catch((err) => setError(errorMessage(err)))
+  }, [invoiceId, resolvedParams.id])
+
+  useEffect(() => {
+    if (!invoice || invoice.status !== "Draft") {
+      setPostingCheck(null)
+      return
+    }
+    salesApi
+      .checkInvoicePosting(invoiceId)
+      .then((result) => setPostingCheck(result))
+      .catch(() => setPostingCheck(null))
+  }, [invoice, invoiceId])
+
+  const isDraft = invoice?.status === "Draft"
+  const customer = useMemo(() => customers.find((c) => c.customerId === invoice?.customerId), [customers, invoice?.customerId])
+  const warehouse = useMemo(() => warehouses.find((w) => w.warehouseId === invoice?.warehouseId), [warehouses, invoice?.warehouseId])
+  const freeQtyTotal = invoice?.totals.freeQtyTotal ?? 0
+  const canPost = invoice?.status === "Draft" && (postingCheck?.canPost ?? true) && !busy && !saving
+
+  function updateLine(key: string, patch: Partial<Line>) {
+    setLines((prev) => prev.map((line) => (line.key === key ? { ...line, ...patch } : line)))
+  }
+
+  function updateHeaderWarehouse(nextWarehouseId: number | null) {
+    setWarehouseId(nextWarehouseId)
+    setLines((prev) => prev.map((line) => ({ ...line, warehouseId: nextWarehouseId ?? line.warehouseId })))
+  }
+
+  function selectItem(key: string, itemId: number) {
+    const item = items.find((candidate) => candidate.itemId === itemId)
+    updateLine(key, {
+      itemId,
+      uomId: item?.baseUomId ?? 0,
+      unitPrice: getSuggestedUnitPrice(items, itemId),
+    })
+  }
+
+  function addLine() {
+    setLines((prev) => [...prev, { ...blankLine(`line-${Date.now()}`), warehouseId: warehouseId ?? 0 }])
+  }
+
+  function removeLine(key: string) {
+    setLines((prev) => (prev.length === 1 ? prev : prev.filter((line) => line.key !== key)))
+  }
+
+  async function save() {
+    if (!customerId || !warehouseId || !etag) return
+    if (lines.some((line) => !line.itemId || !line.uomId || !line.warehouseId)) {
+      setError("Select item, UOM and warehouse for every line.")
+      return
+    }
+
+    setSaving(true)
+    setError(null)
+    try {
+      const updated = await salesApi.updateInvoice(
+        invoiceId,
+        {
+          customerId,
+          warehouseId,
+          invoiceType,
+          lines: lines.map((line) => ({
+            itemId: Number(line.itemId),
+            uomId: Number(line.uomId),
+            warehouseId: Number(line.warehouseId),
+            qty: Number(line.qty),
+            freeQty: Number(line.freeQty),
+            unitPrice: line.unitPrice === null ? null : Number(line.unitPrice),
+            allowManualPriceOverride: line.allowManualPriceOverride,
+            discountMode: line.discountMode,
+            discountPct: Number(line.discountPct),
+            discountAmount: Number(line.discountAmount),
+            discountValue: Number(line.discountValue),
+            taxPct: Number(line.taxPct),
+            isFreeIssue: line.isFreeIssue,
+            parentLineId: line.parentLineId || null,
+          })),
+        },
+        etag,
+      )
+      setInvoice(updated.data)
+      setEtag(updated.etag)
+      toast.success("Invoice saved", updated.data.invoiceNo)
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  async function post() {
+    if (!postingCheck?.canPost) {
+      setError("Resolve stock shortages before posting this invoice.")
+      return
+    }
+    setBusy("post")
+    setError(null)
+    try {
+      const posted = await salesApi.postInvoice(invoiceId)
+      setInvoice(posted)
+      toast.success("Invoice posted", posted.invoiceNo)
+      router.refresh()
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setBusy(null)
+    }
+  }
+
+  async function cancel() {
+    setBusy("cancel")
+    setError(null)
+    try {
+      const cancelled = await salesApi.cancelInvoice(invoiceId)
+      setInvoice(cancelled)
+      toast.success("Invoice cancelled", cancelled.invoiceNo)
+      router.refresh()
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setBusy(null)
+    }
+  }
+
+  if (error && !invoice) {
+    return <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-destructive">{error}</div>
+  }
+
+  if (!invoice) {
+    return <div className="rounded-2xl border border-dashed p-8 text-muted-foreground">{error ?? "Invoice data is loading or unavailable."}</div>
+  }
+
+  return (
+    <div className="mx-auto flex w-full max-w-5xl flex-col gap-6">
+      <div className="flex items-center justify-between gap-3 print:hidden">
+        <div className="flex items-center gap-3">
+          <Link href="/dashboard/sales/invoices" className={cn("inline-flex h-10 w-10 items-center justify-center rounded-full border border-black bg-white text-sm font-medium shadow-sm hover:bg-muted")}>
+            <ArrowLeft className="size-4" />
+          </Link>
+          <div>
+            <h1 className="text-2xl font-bold text-foreground">Invoice Details</h1>
+            <p className="text-base text-muted-foreground">{invoice.invoiceNo}</p>
+          </div>
+        </div>
+        <Link href={`/dashboard/sales/invoices/${invoice.salesInvoiceId}/print`} className={cn("inline-flex h-10 items-center gap-2 rounded-full border border-black bg-white px-4 text-sm font-medium shadow-sm hover:bg-muted")}>
+          <Printer className="size-4" />
+          Print
+        </Link>
+      </div>
+
+      {error ? <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-destructive">{error}</div> : null}
+
+      <section className="bg-white print:bg-white">
+        <div className="border-b pb-4">
+          <div className="flex flex-col gap-3 md:flex-row md:items-start md:justify-between">
+            <div>
+              <div className="text-xs font-semibold uppercase tracking-[0.35em] text-muted-foreground">Sales Invoice</div>
+              <h2 className="mt-2 text-3xl font-semibold text-foreground">{invoice.invoiceNo}</h2>
+              <div className="mt-1 flex flex-wrap items-center gap-2 text-sm text-muted-foreground">
+                <span>Status:</span>
+                <span className={cn("inline-flex rounded-full border px-2 py-0.5 text-xs font-medium", statusClass(invoice.status))}>{invoice.status}</span>
+                <span>Type: {invoice.invoiceType}</span>
+                <span>Date: {new Date(invoice.invoiceDate).toLocaleDateString()}</span>
+              </div>
+            </div>
+            <div className="text-sm md:text-right">
+              <div className="font-semibold text-foreground">{company?.tradeName ?? company?.legalName ?? "ERP Core Trading"}</div>
+              <div className="text-muted-foreground">
+                {company?.addressLine1 ?? ""}
+                {company?.city ? `, ${company.city}` : ""}
+              </div>
+              {company?.taxRegistrationNo ? <div className="text-muted-foreground">Tax No: {company.taxRegistrationNo}</div> : null}
+            </div>
+          </div>
+        </div>
+
+        <div className="grid gap-6 py-5 md:grid-cols-3">
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Bill To</div>
+            <div className="mt-2 font-semibold text-foreground">{invoice.customerSnapshotName}</div>
+            <div className="text-sm text-muted-foreground">Customer ID: {invoice.customerId}</div>
+            {customer?.displayName ? <div className="text-sm text-muted-foreground">Registered name: {customer.displayName}</div> : null}
+            {invoice.customerSnapshotTaxNo ? <div className="text-sm text-muted-foreground">Tax No: {invoice.customerSnapshotTaxNo}</div> : null}
+          </div>
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Warehouse</div>
+            <div className="mt-2 font-semibold text-foreground">{warehouse?.name ?? `#${invoice.warehouseId}`}</div>
+            <div className="text-sm text-muted-foreground">Code: {warehouse?.code ?? invoice.warehouseId}</div>
+            <div className="text-sm text-muted-foreground">Location: {warehouse?.location ?? "—"}</div>
+          </div>
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Totals</div>
+            <div className="mt-2 grid grid-cols-2 gap-2 text-sm">
+              <div className="text-muted-foreground">Subtotal</div>
+              <div className="text-right font-medium">{money.format(invoice.totals.subtotal)}</div>
+              <div className="text-muted-foreground">Discount</div>
+              <div className="text-right font-medium">{money.format(invoice.totals.discountTotal)}</div>
+              <div className="text-muted-foreground">Free qty</div>
+              <div className="text-right font-medium">{freeQtyTotal.toFixed(0)}</div>
+              <div className="text-muted-foreground">Tax</div>
+              <div className="text-right font-medium">{money.format(invoice.totals.taxTotal)}</div>
+              <div className="text-muted-foreground">Net payable</div>
+              <div className="text-right font-semibold">{money.format(invoice.totals.netPayable)}</div>
+            </div>
+          </div>
+        </div>
+
+        <div className="overflow-x-auto border-y">
+          <table className="w-full text-sm">
+            <thead className="bg-secondary/60 text-[11px] uppercase tracking-wide text-muted-foreground">
+              <tr>
+                <th className="px-4 py-2 text-left font-medium">Item</th>
+                <th className="px-4 py-2 text-left font-medium">UOM</th>
+                <th className="px-4 py-2 text-right font-medium">Qty</th>
+                <th className="px-4 py-2 text-right font-medium">Free</th>
+                <th className="px-4 py-2 text-right font-medium">Unit price</th>
+                <th className="px-4 py-2 text-right font-medium">Discount</th>
+                <th className="px-4 py-2 text-right font-medium">Tax</th>
+                <th className="px-4 py-2 text-right font-medium">Line total</th>
+              </tr>
+            </thead>
+            <tbody>
+              {invoice.lines.map((line) => (
+                <tr key={line.salesInvoiceLineId} className="border-t border-border">
+                  <td className="px-4 py-3">
+                    <div className="font-medium text-foreground">{line.description}</div>
+                    <div className="text-xs text-muted-foreground">SKU {items.find((i) => i.itemId === line.itemId)?.sku ?? `#${line.itemId}`}</div>
+                  </td>
+                  <td className="px-4 py-3">{uoms.find((u) => u.uomId === line.uomId)?.name ?? `#${line.uomId}`}</td>
+                  <td className="px-4 py-3 text-right">{line.qty.toFixed(0)}</td>
+                  <td className="px-4 py-3 text-right">{line.freeQty > 0 ? line.freeQty.toFixed(0) : "—"}</td>
+                  <td className="px-4 py-3 text-right">{money.format(line.unitPrice)}</td>
+                  <td className="px-4 py-3 text-right">{money.format(line.discountAmount)}</td>
+                  <td className="px-4 py-3 text-right">{money.format(line.taxAmount)}</td>
+                  <td className="px-4 py-3 text-right font-medium">{money.format(line.lineTotal)}</td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </div>
+
+        {invoice.lines.some((line) => line.freeQty > 0) ? (
+          <div className="py-5">
+            <div className="text-sm font-semibold uppercase tracking-wide text-muted-foreground">Free issue summary</div>
+            <div className="mt-3 space-y-2">
+              {invoice.lines.filter((line) => line.freeQty > 0).map((line) => (
+                <div key={line.salesInvoiceLineId} className="flex items-center justify-between text-sm">
+                  <div className="text-foreground">{line.description}</div>
+                  <div className="text-muted-foreground">Free qty: {line.freeQty.toFixed(0)}</div>
+                </div>
+              ))}
+            </div>
+          </div>
+        ) : null}
+
+        {invoice.status === "Draft" && postingCheck && !postingCheck.canPost ? (
+          <div className="border-t pt-5">
+            <div className="rounded-lg border border-amber-200 bg-amber-50 p-4 text-sm text-amber-900">
+              <div className="font-semibold">Stock shortage detected before posting</div>
+              <div className="mt-1 text-sm">The invoice cannot be posted until every line has enough available stock in the selected warehouse.</div>
+              <div className="mt-3 overflow-x-auto">
+                <table className="w-full text-sm">
+                  <thead className="text-left text-xs uppercase tracking-wide text-amber-900/70">
+                    <tr>
+                      <th className="py-1 pr-3">Item</th>
+                      <th className="py-1 pr-3">Warehouse</th>
+                      <th className="py-1 pr-3 text-right">Requested</th>
+                      <th className="py-1 pr-3 text-right">Available</th>
+                      <th className="py-1 text-right">Short</th>
+                    </tr>
+                  </thead>
+                  <tbody>
+                    {postingCheck.issues.map((issue) => (
+                      <tr key={issue.salesInvoiceLineId} className="border-t border-amber-200/60">
+                        <td className="py-2 pr-3">
+                          <div className="font-medium">{issue.itemSku}</div>
+                          <div className="text-xs text-amber-900/70">{issue.itemName}{issue.isFreeIssue ? " · free issue" : ""}</div>
+                        </td>
+                        <td className="py-2 pr-3">{issue.warehouseId}</td>
+                        <td className="py-2 pr-3 text-right font-mono tabular-nums">{issue.requestedQty.toFixed(0)}</td>
+                        <td className="py-2 pr-3 text-right font-mono tabular-nums">{issue.availableQty.toFixed(0)}</td>
+                        <td className="py-2 text-right font-mono tabular-nums">{issue.shortQty.toFixed(0)}</td>
+                      </tr>
+                    ))}
+                  </tbody>
+                </table>
+              </div>
+            </div>
+          </div>
+        ) : null}
+
+        <div className="border-t pt-5">
+          <div className="text-sm font-semibold uppercase tracking-wide text-muted-foreground">Notes</div>
+          <p className="mt-2 text-sm text-muted-foreground">{company?.footerNote ?? "Standard invoice template view."}</p>
+        </div>
+
+        <div className="mt-6 border-t pt-5 print:hidden">
+          <div className="mb-3 flex items-center justify-between">
+            <h3 className="text-lg font-semibold">Actions</h3>
+            <span className="text-sm text-muted-foreground">{isDraft ? "Draft invoice can be edited." : "Only draft invoices are editable."}</span>
+          </div>
+
+          {isDraft ? (
+            <>
+              <div className="mb-4 flex flex-wrap gap-2">
+                <button type="button" onClick={addLine} className="inline-flex h-9 items-center gap-2 rounded-full border border-black bg-white px-4 text-sm font-medium shadow-sm hover:bg-muted">
+                  <Plus className="size-4" /> Add line
+                </button>
+                <button type="button" onClick={save} disabled={saving} className="inline-flex h-9 items-center gap-2 rounded-full border border-black bg-white px-4 text-sm font-medium shadow-sm hover:bg-muted disabled:opacity-50">
+                  <Save className="size-4" />
+                  {saving ? "Saving..." : "Save invoice"}
+                </button>
+                <button type="button" onClick={post} disabled={!canPost} className="inline-flex h-9 items-center gap-2 rounded-full bg-black px-4 text-sm font-medium text-white shadow-sm hover:bg-black/90 disabled:cursor-not-allowed disabled:opacity-40">
+                  <Send className="size-4" />
+                  {postingCheck && !postingCheck.canPost ? "Resolve shortages first" : busy === "post" ? "Posting..." : "Post invoice"}
+                </button>
+                <button type="button" onClick={cancel} disabled={busy !== null} className="inline-flex h-9 items-center gap-2 rounded-full border border-rose-300 bg-rose-50 px-4 text-sm font-medium text-rose-700 shadow-sm hover:bg-rose-100 disabled:opacity-50">
+                  <X className="size-4" />
+                  {busy === "cancel" ? "Cancelling..." : "Cancel invoice"}
+                </button>
+              </div>
+
+              <div className="overflow-x-auto border">
+                <table className="w-full text-sm">
+                  <thead className="bg-secondary/60 text-[11px] uppercase tracking-wide text-muted-foreground">
+                    <tr>
+                      <th className="px-4 py-2 text-left font-medium">Item</th>
+                      <th className="px-4 py-2 text-left font-medium">UOM</th>
+                      <th className="px-4 py-2 text-right font-medium">Qty</th>
+                      <th className="px-4 py-2 text-right font-medium">Free</th>
+                      <th className="px-4 py-2 text-right font-medium">Unit price</th>
+                      <th className="px-4 py-2 text-right font-medium">Remove</th>
+                    </tr>
+                  </thead>
+                  <tbody>
+                    {lines.map((line) => (
+                      <tr key={line.key} className="border-t border-border align-middle">
+                        <td className="px-4 py-3 min-w-64">
+                          <select
+                            value={line.itemId ? String(line.itemId) : ""}
+                            onChange={(e) => selectItem(line.key, Number(e.target.value))}
+                            className="h-10 w-full rounded-lg border border-input bg-background px-3 text-sm"
+                          >
+                            <option value="">Select item</option>
+                            {items.map((i) => (
+                              <option key={i.itemId} value={String(i.itemId)}>
+                                {i.sku} - {i.name}
+                              </option>
+                            ))}
+                          </select>
+                        </td>
+                        <td className="px-4 py-3 min-w-40">
+                          <select
+                            value={line.uomId ? String(line.uomId) : ""}
+                            onChange={(e) => updateLine(line.key, { uomId: Number(e.target.value) })}
+                            className="h-10 w-full rounded-lg border border-input bg-background px-3 text-sm"
+                          >
+                            <option value="">UOM</option>
+                            {uoms.map((u) => (
+                              <option key={u.uomId} value={String(u.uomId)}>
+                                {u.name}
+                              </option>
+                            ))}
+                          </select>
+                        </td>
+                        <td className="px-4 py-3 w-28">
+                          <input
+                            type="number"
+                            min="0"
+                            step="1"
+                            value={line.qty}
+                            onChange={(e) => updateLine(line.key, { qty: Number(e.target.value) || 0 })}
+                            className="h-10 w-full rounded-lg border border-input bg-background px-3 text-right font-mono tabular-nums text-sm"
+                          />
+                        </td>
+                        <td className="px-4 py-3 w-28">
+                          <input
+                            type="number"
+                            min="0"
+                            step="1"
+                            value={line.freeQty}
+                            onChange={(e) => updateLine(line.key, { freeQty: Number(e.target.value) || 0 })}
+                            className="h-10 w-full rounded-lg border border-input bg-background px-3 text-right font-mono tabular-nums text-sm"
+                          />
+                        </td>
+                        <td className="px-4 py-3 w-32">
+                          <input
+                            type="number"
+                            min="0"
+                            step="0.01"
+                            value={line.unitPrice ?? ""}
+                            onChange={(e) => updateLine(line.key, { unitPrice: e.target.value === "" ? null : Number(e.target.value) })}
+                            className="h-10 w-full rounded-lg border border-input bg-background px-3 text-right font-mono tabular-nums text-sm"
+                          />
+                        </td>
+                        <td className="px-4 py-3 w-24 text-right">
+                    <button
+                      type="button"
+                      onClick={() => removeLine(line.key)}
+                      disabled={lines.length === 1}
+                            className="inline-flex h-9 w-9 items-center justify-center rounded-full border border-black bg-white text-sm font-medium shadow-sm hover:bg-muted disabled:opacity-50"
+                          >
+                            <Minus className="size-4" />
+                          </button>
+                        </td>
+                      </tr>
+                    ))}
+                  </tbody>
+                </table>
+              </div>
+
+              <div className="mt-5 grid gap-4 md:grid-cols-3">
+                <div className="space-y-1.5">
+                  <Label className="text-xs">Customer</Label>
+                  <select
+                    value={customerId ? String(customerId) : ""}
+                    onChange={(e) => setCustomerId(e.target.value ? Number(e.target.value) : null)}
+                    className="h-10 w-full rounded-lg border border-input bg-background px-3 text-sm"
+                  >
+                    <option value="">Select customer</option>
+                    {customers.map((c) => (
+                      <option key={c.customerId} value={String(c.customerId)}>
+                        {c.customerCode} - {c.displayName ?? c.name}
+                      </option>
+                    ))}
+                  </select>
+                </div>
+                <div className="space-y-1.5">
+                  <Label className="text-xs">Warehouse</Label>
+                  <select
+                    value={warehouseId ? String(warehouseId) : ""}
+                    onChange={(e) => updateHeaderWarehouse(e.target.value ? Number(e.target.value) : null)}
+                    className="h-10 w-full rounded-lg border border-input bg-background px-3 text-sm"
+                  >
+                    <option value="">Select warehouse</option>
+                    {warehouses.map((w) => (
+                      <option key={w.warehouseId} value={String(w.warehouseId)}>
+                        {w.code} - {w.name}
+                      </option>
+                    ))}
+                  </select>
+                </div>
+                <div className="space-y-1.5">
+                  <Label className="text-xs">Invoice type</Label>
+                  <select
+                    value={invoiceType}
+                    onChange={(e) => setInvoiceType(e.target.value as SalesInvoiceType)}
+                    className="h-10 w-full rounded-lg border border-input bg-background px-3 text-sm"
+                  >
+                    <option value="B2B">B2B</option>
+                    <option value="B2C">B2C</option>
+                    <option value="Cash">Cash</option>
+                    <option value="Credit">Credit</option>
+                  </select>
+                </div>
+              </div>
+              <div className="mt-5 flex justify-end">
+                <button
+                  type="button"
+                  onClick={post}
+                  disabled={!canPost}
+                  className="inline-flex h-10 items-center gap-2 rounded-full bg-black px-5 text-sm font-medium text-white shadow-sm hover:bg-black/90 disabled:cursor-not-allowed disabled:opacity-40"
+                >
+                  <Send className="size-4" />
+                  {postingCheck && !postingCheck.canPost ? "Resolve shortages first" : busy === "post" ? "Posting..." : "Post invoice"}
+                </button>
+              </div>
+            </>
+          ) : (
+            <div className="rounded-2xl border border-dashed p-4 text-sm text-muted-foreground">
+              This invoice is {invoice.status.toLowerCase()} and cannot be edited.
+            </div>
+          )}
+        </div>
+      </section>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/invoices/[id]/print/page.tsx

@@ -0,0 +1,218 @@
+"use client"
+
+import { useEffect, useMemo, useState } from "react"
+import Link from "next/link"
+import { ArrowLeft, Printer } from "lucide-react"
+
+import { salesApi } from "@/lib/api/sales"
+import { companyApi } from "@/lib/api/company"
+import { customersApi } from "@/lib/api/customers"
+import { itemsApi } from "@/lib/api/items"
+import { uomsApi } from "@/lib/api/uoms"
+import { warehousesApi } from "@/lib/api/warehouses"
+import { errorMessage } from "@/lib/error-map"
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Skeleton } from "@/components/ui/skeleton"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { cn } from "@/lib/utils"
+import { Customer } from "@/types/customers"
+import { CompanyProfile } from "@/types/company"
+import { ItemListItem, Uom, Warehouse } from "@/types/master-data"
+import { SalesInvoice } from "@/types/sales"
+
+export default function SalesInvoicePrintPage({ params }: { params: { id: string } }) {
+  const invoiceId = Number(params.id)
+  const [invoice, setInvoice] = useState<SalesInvoice | null>(null)
+  const [company, setCompany] = useState<CompanyProfile | null>(null)
+  const [customers, setCustomers] = useState<Customer[]>([])
+  const [items, setItems] = useState<ItemListItem[]>([])
+  const [uoms, setUoms] = useState<Uom[]>([])
+  const [warehouses, setWarehouses] = useState<Warehouse[]>([])
+  const [error, setError] = useState<string | null>(null)
+
+  useEffect(() => {
+    if (!Number.isFinite(invoiceId)) {
+      setError(`Invalid invoice id '${params.id}'.`)
+      return
+    }
+    Promise.all([
+      companyApi.getProfile(),
+      customersApi.list({ pageSize: 200 }),
+      itemsApi.list({ pageSize: 200 }),
+      uomsApi.list({ pageSize: 200 }),
+      warehousesApi.list({ pageSize: 200 }),
+      salesApi.getInvoice(invoiceId),
+    ])
+      .then(([companyRes, cust, itemRes, uomRes, whRes, doc]) => {
+        setCompany(companyRes.data)
+        setCustomers(cust.items)
+        setItems(itemRes.items)
+        setUoms(uomRes.items)
+        setWarehouses(whRes.items)
+        setInvoice(doc.data)
+      })
+      .catch((err) => setError(errorMessage(err)))
+  }, [params.id, invoiceId])
+
+  const subtotal = useMemo(() => invoice?.totals.subtotal ?? 0, [invoice])
+  const freeQtyTotal = invoice?.totals.freeQtyTotal ?? 0
+
+  if (error && !invoice) {
+    return <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>
+  }
+
+  if (!invoice) {
+    return <div className="rounded-2xl border border-dashed p-8 text-muted-foreground">{error ?? "Invoice print data is loading or unavailable."}</div>
+  }
+
+  const customer = customers.find((c) => c.customerId === invoice.customerId)
+  const warehouse = warehouses.find((w) => w.warehouseId === invoice.warehouseId)
+
+  return (
+    <div className="flex flex-col gap-6 print:block print:gap-0">
+      <div className="flex items-center justify-between gap-3 print:hidden">
+        <div className="flex items-center gap-3">
+          <Link href={`/dashboard/sales/invoices/${invoice.salesInvoiceId}`} className={cn(buttonVariants({ variant: "outline", size: "icon" }))}>
+            <ArrowLeft className="size-4" />
+          </Link>
+          <div>
+            <h1 className="text-2xl font-bold text-foreground">Invoice Print</h1>
+            <p className="text-base text-muted-foreground">{invoice.invoiceNo}</p>
+          </div>
+        </div>
+        <Button variant="outline" onClick={() => window.print()}>
+          <Printer className="size-4" />
+          Print
+        </Button>
+      </div>
+
+      <div className="invoice-sheet rounded-3xl border bg-white p-6 shadow-sm print:rounded-none print:border-0 print:p-0 print:shadow-none">
+        <div className="invoice-header mb-6 grid gap-4 border-b pb-5 md:grid-cols-[1.4fr_1fr]">
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-[0.3em] text-muted-foreground">Sales Invoice</div>
+            <h1 className="mt-2 text-3xl font-semibold text-foreground">{invoice.invoiceNo}</h1>
+            <div className="mt-2 text-sm text-muted-foreground">Status: {invoice.status} · Type: {invoice.invoiceType}</div>
+          </div>
+          <div className="grid gap-2 text-sm md:justify-items-end">
+            <div className="font-semibold text-foreground">{company?.tradeName ?? company?.legalName ?? "ERP Core Trading"}</div>
+            {company?.logoUrl ? <img src={company.logoUrl} alt={company.tradeName ?? company.legalName} className="h-12 w-auto object-contain" /> : null}
+            <div className="text-muted-foreground">{company?.addressLine1}{company?.city ? `, ${company.city}` : ""}</div>
+            {company?.taxRegistrationNo ? <div className="text-muted-foreground">Tax No: {company.taxRegistrationNo}</div> : null}
+            <div className="text-muted-foreground">Invoice date: {new Date(invoice.invoiceDate).toLocaleDateString()}</div>
+            <div className="text-muted-foreground">Printed: {new Date().toLocaleString()}</div>
+            <div className="text-muted-foreground">Free qty total: {freeQtyTotal.toFixed(2)}</div>
+          </div>
+        </div>
+
+        <div className="grid gap-4 md:grid-cols-3">
+          <div className="rounded-2xl border bg-muted/20 p-4">
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Customer</div>
+            <div className="mt-2 text-lg font-semibold text-foreground">{invoice.customerSnapshotName}</div>
+            <div className="mt-1 text-sm text-muted-foreground">Customer ID: {invoice.customerId}</div>
+            {invoice.customerSnapshotTaxNo ? <div className="mt-1 text-sm text-muted-foreground">Tax No: {invoice.customerSnapshotTaxNo}</div> : null}
+            {customer?.displayName ? <div className="mt-1 text-sm text-muted-foreground">Customer: {customer.displayName}</div> : null}
+          </div>
+          <div className="rounded-2xl border bg-muted/20 p-4">
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Warehouse</div>
+            <div className="mt-2 text-lg font-semibold text-foreground">{warehouse?.name ?? `#${invoice.warehouseId}`}</div>
+            <div className="mt-1 text-sm text-muted-foreground">Code: {warehouse?.code ?? invoice.warehouseId}</div>
+          </div>
+          <div className="rounded-2xl border bg-muted/20 p-4">
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Totals</div>
+            <div className="mt-2 grid grid-cols-2 gap-2 text-sm">
+              <div className="text-muted-foreground">Subtotal</div><div className="text-right font-medium">{invoice.totals.subtotal.toFixed(2)}</div>
+              <div className="text-muted-foreground">Discount</div><div className="text-right font-medium">{invoice.totals.discountTotal.toFixed(2)}</div>
+              <div className="text-muted-foreground">Free qty</div><div className="text-right font-medium">{freeQtyTotal.toFixed(2)}</div>
+              <div className="text-muted-foreground">Tax</div><div className="text-right font-medium">{invoice.totals.taxTotal.toFixed(2)}</div>
+              <div className="text-muted-foreground">Net payable</div><div className="text-right font-semibold">{invoice.totals.netPayable.toFixed(2)}</div>
+            </div>
+          </div>
+        </div>
+
+        <div className="mt-6 overflow-hidden rounded-2xl border">
+          <Table>
+            <TableHeader>
+              <TableRow>
+                <TableHead className="w-[34%]">Item</TableHead>
+                <TableHead>UOM</TableHead>
+                <TableHead className="text-right">Qty</TableHead>
+                <TableHead className="text-right">Free</TableHead>
+                <TableHead className="text-right">Unit price</TableHead>
+                <TableHead className="text-right">Discount</TableHead>
+                <TableHead className="text-right">Tax</TableHead>
+                <TableHead className="text-right">Line total</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {invoice.lines.map((line) => (
+                <TableRow key={line.salesInvoiceLineId}>
+                  <TableCell>
+                    <div className="font-medium text-foreground">{line.description}</div>
+                    <div className="text-xs text-muted-foreground">SKU {items.find((i) => i.itemId === line.itemId)?.sku ?? `#${line.itemId}`}</div>
+                  </TableCell>
+                  <TableCell>{uoms.find((u) => u.uomId === line.uomId)?.name ?? `#${line.uomId}`}</TableCell>
+                  <TableCell className="text-right">{line.qty.toFixed(2)}</TableCell>
+                  <TableCell className="text-right">{line.freeQty > 0 ? line.freeQty.toFixed(2) : "—"}</TableCell>
+                  <TableCell className="text-right">{line.unitPrice.toFixed(2)}</TableCell>
+                  <TableCell className="text-right">{line.discountAmount.toFixed(2)}</TableCell>
+                  <TableCell className="text-right">{line.taxAmount.toFixed(2)}</TableCell>
+                  <TableCell className="text-right font-medium">{line.lineTotal.toFixed(2)}</TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </div>
+
+        {invoice.lines.some((line) => line.freeQty > 0) ? (
+          <div className="mt-6 rounded-2xl border border-dashed p-4 print:break-inside-avoid">
+            <div className="text-sm font-semibold uppercase tracking-wide text-muted-foreground">Free issue summary</div>
+            <div className="mt-3 grid gap-3 md:grid-cols-2 xl:grid-cols-3">
+              {invoice.lines.filter((line) => line.freeQty > 0).map((line) => (
+                <div key={line.salesInvoiceLineId} className="rounded-xl border bg-emerald-500/5 p-3">
+                  <div className="font-medium text-foreground">{line.description}</div>
+                  <div className="mt-1 text-sm text-muted-foreground">Invoice qty: {line.qty.toFixed(2)}</div>
+                  <div className="mt-1 text-sm text-foreground">Free qty: {line.freeQty.toFixed(2)}</div>
+                </div>
+              ))}
+            </div>
+          </div>
+        ) : null}
+
+        <div className="mt-6 grid gap-4 lg:grid-cols-[1fr_360px]">
+          <div className="rounded-2xl border bg-muted/20 p-4">
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Notes</div>
+            <p className="mt-2 text-sm text-muted-foreground">
+              {company?.footerNote ?? "Standard invoice print view."}
+            </p>
+          </div>
+          <div className="rounded-2xl border p-4">
+            <div className="text-sm font-semibold uppercase tracking-wide text-muted-foreground">Totals</div>
+            <div className="mt-3 space-y-2 text-sm">
+              <div className="flex justify-between"><span className="text-muted-foreground">Subtotal</span><span>{invoice.totals.subtotal.toFixed(2)}</span></div>
+              <div className="flex justify-between"><span className="text-muted-foreground">Discount total</span><span>{invoice.totals.discountTotal.toFixed(2)}</span></div>
+              <div className="flex justify-between"><span className="text-muted-foreground">Free qty total</span><span>{invoice.totals.freeQtyTotal.toFixed(2)}</span></div>
+              <div className="flex justify-between"><span className="text-muted-foreground">Tax total</span><span>{invoice.totals.taxTotal.toFixed(2)}</span></div>
+              <div className="flex justify-between border-t pt-2 text-base font-semibold"><span>Net payable</span><span>{invoice.totals.netPayable.toFixed(2)}</span></div>
+              <div className="flex justify-between text-muted-foreground"><span>Paid</span><span>{invoice.totals.paidAmount.toFixed(2)}</span></div>
+              <div className="flex justify-between text-muted-foreground"><span>Balance</span><span>{invoice.totals.balanceAmount.toFixed(2)}</span></div>
+            </div>
+          </div>
+        </div>
+
+        {company ? (
+          <div className="mt-6 rounded-2xl border bg-muted/20 p-4">
+            <div className="text-sm font-semibold uppercase tracking-wide text-muted-foreground">Bank Details</div>
+            <div className="mt-3 grid gap-2 text-sm md:grid-cols-2">
+              <div><span className="text-muted-foreground">Bank</span> <span className="font-medium">{company.bankName ?? "—"}</span></div>
+              <div><span className="text-muted-foreground">Branch</span> <span className="font-medium">{company.bankBranch ?? "—"}</span></div>
+              <div><span className="text-muted-foreground">Account Name</span> <span className="font-medium">{company.accountName ?? "—"}</span></div>
+              <div><span className="text-muted-foreground">Account No</span> <span className="font-medium">{company.accountNumber ?? "—"}</span></div>
+              <div><span className="text-muted-foreground">SWIFT</span> <span className="font-medium">{company.swiftCode ?? "—"}</span></div>
+              <div><span className="text-muted-foreground">VAT</span> <span className="font-medium">{company.vatRegistrationNo ?? "—"}</span></div>
+            </div>
+          </div>
+        ) : null}
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/invoices/new/page.tsx

@@ -0,0 +1,490 @@
+"use client"
+
+import { useEffect, useMemo, useState } from "react"
+import { useRouter } from "next/navigation"
+import Link from "next/link"
+import { ArrowLeft, Minus, Plus, Save, Trash2 } from "lucide-react"
+
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Label } from "@/components/ui/label"
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select"
+import { Badge } from "@/components/ui/badge"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { cn } from "@/lib/utils"
+import { getSuggestedUnitPrice } from "@/lib/sales-line-utils"
+import { errorMessage } from "@/lib/error-map"
+import { salesApi } from "@/lib/api/sales"
+import { customersApi } from "@/lib/api/customers"
+import { itemsApi } from "@/lib/api/items"
+import { uomsApi } from "@/lib/api/uoms"
+import { warehousesApi } from "@/lib/api/warehouses"
+import { Customer } from "@/types/customers"
+import { ItemListItem, Uom, Warehouse } from "@/types/master-data"
+import { CreateSalesInvoiceLineRequest, CreateSalesInvoiceRequest, SalesInvoiceType } from "@/types/sales"
+import { toast } from "@/components/ui/toast"
+
+type Line = CreateSalesInvoiceLineRequest & { key: string }
+type ActiveFocScheme = {
+  id: number
+  slipNo: string
+  schemeLabel: string
+  warehouseName: string
+  productLabel: string
+}
+
+const blankLine = (key: string): Line => ({
+  key,
+  itemId: 0,
+  uomId: 0,
+  warehouseId: 0,
+  qty: 1,
+  freeQty: 0,
+  unitPrice: null,
+  allowManualPriceOverride: true,
+  discountMode: "Percentage",
+  discountPct: 0,
+  discountAmount: 0,
+  discountValue: 0,
+  taxPct: 0,
+  isFreeIssue: false,
+  parentLineId: null,
+})
+
+const lkr = new Intl.NumberFormat("en-LK", {
+  style: "currency",
+  currency: "LKR",
+  minimumFractionDigits: 2,
+})
+
+export default function NewSalesInvoicePage() {
+  const router = useRouter()
+  const [customers, setCustomers] = useState<Customer[]>([])
+  const [items, setItems] = useState<ItemListItem[]>([])
+  const [uoms, setUoms] = useState<Uom[]>([])
+  const [warehouses, setWarehouses] = useState<Warehouse[]>([])
+  const [customerId, setCustomerId] = useState<number | null>(null)
+  const [warehouseId, setWarehouseId] = useState<number | null>(null)
+  const [invoiceType, setInvoiceType] = useState<SalesInvoiceType>("B2C")
+  const [lines, setLines] = useState<Line[]>([blankLine("line-1")])
+  const [activeFocSchemes, setActiveFocSchemes] = useState<ActiveFocScheme[]>([])
+  const [loading, setLoading] = useState(true)
+  const [submitError, setSubmitError] = useState<string | null>(null)
+  const [saving, setSaving] = useState(false)
+
+  useEffect(() => {
+    Promise.all([
+      customersApi.list({ pageSize: 200 }),
+      itemsApi.list({ pageSize: 200 }),
+      uomsApi.list({ pageSize: 200 }),
+      warehousesApi.list({ pageSize: 200 }),
+      salesApi.listFreeIssues({ pageSize: 20 }),
+    ])
+      .then(([cust, itemRes, uomRes, whRes, freeIssueRes]) => {
+        setCustomers(cust.items)
+        setItems(itemRes.items)
+        setUoms(uomRes.items)
+        setWarehouses(whRes.items)
+        const defaultWarehouseId = whRes.items[0]?.warehouseId ?? null
+        setCustomerId(cust.items[0]?.customerId ?? null)
+        setWarehouseId(defaultWarehouseId)
+        setLines([
+          {
+            ...blankLine("line-1"),
+            itemId: itemRes.items[0]?.itemId ?? 0,
+            uomId: itemRes.items[0]?.baseUomId ?? uomRes.items[0]?.uomId ?? 0,
+            warehouseId: defaultWarehouseId ?? 0,
+            unitPrice: getSuggestedUnitPrice(itemRes.items, itemRes.items[0]?.itemId),
+          },
+        ])
+        setActiveFocSchemes(
+          freeIssueRes.items.flatMap((issue) => {
+            const firstLine = issue.lines?.[0]
+            if (!firstLine) return []
+            const item = itemRes.items.find((candidate) => candidate.itemId === firstLine.itemId)
+            const warehouse = whRes.items.find((candidate) => candidate.warehouseId === issue.warehouseId)
+            return [
+              {
+                id: issue.salesSlipId,
+                slipNo: issue.slipNo,
+                schemeLabel: `Buy ${firstLine.qty} Get ${firstLine.freeQty || 0}`,
+                warehouseName: warehouse?.name ?? `Warehouse ${issue.warehouseId}`,
+                productLabel: `${item?.sku ?? `SKU-${firstLine.itemId}`} - ${item?.name ?? firstLine.itemName ?? `Item ${firstLine.itemId}`}`,
+              },
+            ]
+          }),
+        )
+      })
+      .catch((err) => setSubmitError(errorMessage(err)))
+      .finally(() => setLoading(false))
+  }, [])
+
+  function updateLine(key: string, patch: Partial<Line>) {
+    setLines((prev) => prev.map((line) => (line.key === key ? { ...line, ...patch } : line)))
+  }
+
+  function updateHeaderWarehouse(nextWarehouseId: number | null) {
+    setWarehouseId(nextWarehouseId)
+    setLines((prev) => prev.map((line) => ({ ...line, warehouseId: nextWarehouseId ?? line.warehouseId })))
+  }
+
+  function selectItem(key: string, itemId: number) {
+    const item = items.find((candidate) => candidate.itemId === itemId)
+    updateLine(key, {
+      itemId,
+      uomId: item?.baseUomId ?? 0,
+      unitPrice: getSuggestedUnitPrice(items, itemId),
+    })
+  }
+
+  function addLine() {
+    setLines((prev) => [
+      ...prev,
+      {
+        ...blankLine(`line-${Date.now()}`),
+        warehouseId: warehouseId ?? 0,
+      },
+    ])
+  }
+
+  function removeLine(key: string) {
+    setLines((prev) => (prev.length === 1 ? prev : prev.filter((line) => line.key !== key)))
+  }
+
+  const grossTotal = useMemo(
+    () => lines.reduce((sum, line) => sum + Number(line.unitPrice ?? 0) * Number(line.qty || 0), 0),
+    [lines],
+  )
+  const discountTotal = useMemo(
+    () =>
+      lines.reduce((sum, line) => {
+        const gross = Number(line.unitPrice ?? 0) * Number(line.qty || 0)
+        const mode = String(line.discountMode)
+        return sum + (mode === "Amount" ? Number(line.discountAmount || 0) : gross * (Number(line.discountPct || 0) / 100))
+      }, 0),
+    [lines],
+  )
+  const taxTotal = useMemo(
+    () =>
+      lines.reduce((sum, line) => {
+        const gross = Number(line.unitPrice ?? 0) * Number(line.qty || 0)
+        const mode = String(line.discountMode)
+        const discount = mode === "Amount" ? Number(line.discountAmount || 0) : gross * (Number(line.discountPct || 0) / 100)
+        const taxable = Math.max(0, gross - discount)
+        return sum + taxable * (Number(line.taxPct || 0) / 100)
+      }, 0),
+    [lines],
+  )
+  const netTotal = Math.max(0, grossTotal - discountTotal)
+  const payableTotal = netTotal + taxTotal
+
+  async function submit() {
+    if (!customerId || !warehouseId) return setSubmitError("Select a customer and warehouse.")
+    if (lines.some((line) => !line.itemId)) return setSubmitError("Select an item for every line.")
+    if (lines.some((line) => !line.warehouseId)) return setSubmitError("Select a warehouse for every line.")
+    if (lines.some((line) => !line.uomId)) return setSubmitError("Select a valid UOM for every line.")
+
+    const payload: CreateSalesInvoiceRequest = {
+      customerId,
+      warehouseId,
+      invoiceType,
+      lines: lines.map((line) => ({
+        itemId: Number(line.itemId),
+        uomId: Number(line.uomId),
+        warehouseId: Number(line.warehouseId),
+        qty: Number(line.qty),
+        freeQty: Number(line.freeQty),
+        unitPrice: line.unitPrice === null ? null : Number(line.unitPrice),
+        allowManualPriceOverride: line.allowManualPriceOverride,
+        discountMode: line.discountMode,
+        discountPct: Number(line.discountPct),
+        discountAmount: Number(line.discountAmount),
+        discountValue: Number(line.discountValue),
+        taxPct: Number(line.taxPct),
+        isFreeIssue: line.isFreeIssue,
+        parentLineId: line.parentLineId || null,
+      })),
+    }
+
+    setSaving(true)
+    setSubmitError(null)
+    try {
+      const created = await salesApi.createInvoice(payload)
+      toast.success("Invoice created", created.data.invoiceNo)
+      router.push(`/dashboard/sales/invoices/${created.data.salesInvoiceId}`)
+    } catch (err) {
+      if (err instanceof Error && "status" in err && (err as { status?: number }).status === 401) {
+        router.push(`/login?next=/dashboard/sales/invoices/new`)
+        return
+      }
+      setSubmitError(errorMessage(err))
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  if (loading) {
+    return <div className="rounded-2xl border border-border bg-card p-8 text-muted-foreground shadow-[var(--shadow-panel)]">Loading masters...</div>
+  }
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div className="flex items-center gap-3">
+          <Link href="/dashboard/sales/invoices" className={cn(buttonVariants({ variant: "outline", size: "icon" }))}>
+            <ArrowLeft className="size-4" />
+          </Link>
+          <div>
+            <h1 className="text-2xl font-bold text-foreground">New invoice</h1>
+            <p className="text-base text-muted-foreground">Select items, set quantity, unit price and line discount.</p>
+          </div>
+        </div>
+        <div className="flex flex-wrap gap-2">
+          <Button type="button" variant="outline" size="sm" onClick={addLine}>
+            <Plus className="size-4" /> Add line
+          </Button>
+          <Button size="sm" onClick={submit} disabled={saving}>
+            <Save className="size-4" /> {saving ? "Saving..." : "Create & open invoice"}
+          </Button>
+        </div>
+      </div>
+
+      {submitError ? <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{submitError}</div> : null}
+
+      <section className="rounded-2xl border border-border bg-card p-4 shadow-[var(--shadow-panel)]">
+        <h2 className="text-sm font-semibold">Invoice header</h2>
+        <div className="mt-3 grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
+          <div className="space-y-1.5">
+            <Label className="text-xs">Customer</Label>
+            <Select value={customerId ? String(customerId) : ""} onValueChange={(v) => setCustomerId(v ? Number(v) : null)}>
+              <SelectTrigger className="h-9 text-sm">
+                <SelectValue placeholder="Select customer" />
+              </SelectTrigger>
+              <SelectContent>
+                {customers.map((c) => (
+                  <SelectItem key={c.customerId} value={String(c.customerId)}>
+                    {c.customerCode} - {c.displayName ?? c.name}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          <div className="space-y-1.5">
+            <Label className="text-xs">Warehouse</Label>
+            <Select value={warehouseId ? String(warehouseId) : ""} onValueChange={(v) => updateHeaderWarehouse(v ? Number(v) : null)}>
+              <SelectTrigger className="h-9 text-sm">
+                <SelectValue placeholder="Select warehouse" />
+              </SelectTrigger>
+              <SelectContent>
+                {warehouses.map((w) => (
+                  <SelectItem key={w.warehouseId} value={String(w.warehouseId)}>
+                    {w.code} - {w.name}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          <div className="space-y-1.5">
+            <Label className="text-xs">Invoice type</Label>
+            <Select<SalesInvoiceType> value={invoiceType} onValueChange={(v) => v && setInvoiceType(v)}>
+              <SelectTrigger className="h-9 text-sm">
+                <SelectValue />
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem value="B2B">B2B</SelectItem>
+                <SelectItem value="B2C">B2C</SelectItem>
+                <SelectItem value="Cash">Cash</SelectItem>
+                <SelectItem value="Credit">Credit</SelectItem>
+              </SelectContent>
+            </Select>
+          </div>
+          <div className="space-y-1.5">
+            <Label className="text-xs">Invoice summary</Label>
+            <div className="flex h-9 items-center gap-2 rounded-md border border-border bg-secondary/40 px-3 text-xs text-muted-foreground">
+              <Badge variant="outline" className="border-emerald-200 bg-emerald-50 text-emerald-800">
+                Draft
+              </Badge>
+              <span>{lkr.format(payableTotal)}</span>
+            </div>
+          </div>
+        </div>
+      </section>
+
+      <section className="rounded-2xl border border-border bg-card shadow-[var(--shadow-panel)]">
+        <div className="flex items-center justify-between border-b border-border px-4 py-3">
+          <h2 className="text-sm font-semibold">Invoice lines</h2>
+          <Button type="button" variant="outline" size="sm" onClick={addLine}>
+            <Plus className="size-4" /> Add line
+          </Button>
+        </div>
+        <div className="overflow-x-auto">
+          <Table className="text-sm">
+            <TableHeader>
+              <TableRow>
+                <TableHead className="h-12 px-4 text-sm">#</TableHead>
+                <TableHead className="h-12 px-4 text-sm">Item</TableHead>
+                <TableHead className="h-12 px-4 text-sm">UOM</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Qty</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Free</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Unit price</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Discount %</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Line total</TableHead>
+                <TableHead className="h-12 px-4 text-sm" />
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {lines.map((line, idx) => {
+                const lineGross = Number(line.unitPrice ?? 0) * Number(line.qty || 0)
+                const lineDiscount =
+                  line.discountMode === "Amount"
+                    ? Number(line.discountAmount || 0)
+                    : lineGross * (Number(line.discountPct || 0) / 100)
+                const lineNet = Math.max(0, lineGross - lineDiscount)
+
+                return (
+                  <TableRow key={line.key} className="align-middle">
+                    <TableCell className="px-4 py-2 text-xs text-muted-foreground">{idx + 1}</TableCell>
+                    <TableCell className="px-4 py-2 min-w-64">
+                      <Select value={line.itemId ? String(line.itemId) : ""} onValueChange={(v) => selectItem(line.key, Number(v))}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="Select item" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {items.map((candidate) => (
+                            <SelectItem key={candidate.itemId} value={String(candidate.itemId)}>
+                              {candidate.sku} - {candidate.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2 min-w-36">
+                      <Select value={line.uomId ? String(line.uomId) : ""} onValueChange={(v) => updateLine(line.key, { uomId: Number(v) })}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="UOM" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {uoms.map((u) => (
+                            <SelectItem key={u.uomId} value={String(u.uomId)}>
+                              {u.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        step="1"
+                        value={line.qty}
+                        onChange={(e) => updateLine(line.key, { qty: Number(e.target.value) })}
+                        className="h-9 w-24 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        step="1"
+                        value={line.freeQty}
+                        onChange={(e) => updateLine(line.key, { freeQty: Number(e.target.value) })}
+                        className="h-9 w-24 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        step="1"
+                        value={line.unitPrice ?? ""}
+                        onChange={(e) => updateLine(line.key, { unitPrice: e.target.value === "" ? null : Number(e.target.value) })}
+                        className="h-9 w-28 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        max="100"
+                        step="0.5"
+                        value={line.discountPct}
+                        onChange={(e) => updateLine(line.key, { discountPct: Number(e.target.value) || 0 })}
+                        className="h-9 w-24 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2 text-right font-mono font-semibold tabular-nums">{lkr.format(lineNet)}</TableCell>
+                    <TableCell className="px-4 py-2 text-right">
+                      <Button
+                        variant="ghost"
+                        size="icon"
+                        className="size-8 text-muted-foreground"
+                        onClick={() => removeLine(line.key)}
+                        disabled={lines.length === 1}
+                      >
+                        <Trash2 className="size-4" />
+                      </Button>
+                    </TableCell>
+                  </TableRow>
+                )
+              })}
+            </TableBody>
+          </Table>
+        </div>
+      </section>
+
+      <section className="flex justify-end">
+        {/* <div className="rounded-2xl border border-border bg-card p-4 shadow-[var(--shadow-panel)]">
+          <h3 className="text-sm font-semibold">Active FOC schemes</h3>
+          <ul className="mt-3 space-y-2 text-sm">
+            {activeFocSchemes.length > 0 ? (
+              activeFocSchemes.map((scheme) => (
+                <li key={scheme.id} className="rounded-md border border-border px-3 py-2">
+                  <div className="flex items-center justify-between gap-3">
+                    <span className="font-medium">{scheme.schemeLabel}</span>
+                    <span className="text-xs text-muted-foreground">{scheme.slipNo}</span>
+                  </div>
+                  <div className="mt-1 flex flex-wrap items-center justify-between gap-2 text-xs text-muted-foreground">
+                    <span>{scheme.productLabel}</span>
+                    <span>{scheme.warehouseName}</span>
+                  </div>
+                </li>
+              ))
+            ) : (
+              <li className="rounded-md border border-dashed border-border px-3 py-2 text-xs text-muted-foreground">
+                No active free-issue schemes found.
+              </li>
+            )}
+          </ul>
+        </div> */}
+
+        <dl className="w-full max-w-sm rounded-2xl border border-border bg-card p-4 text-sm shadow-[var(--shadow-panel)]">
+          {[
+            ["Gross", lkr.format(grossTotal)],
+            ["Discount", `-${lkr.format(discountTotal)}`],
+            ["Net", lkr.format(netTotal)],
+            ["Tax", lkr.format(taxTotal)],
+          ].map(([k, v]) => (
+            <div key={k} className="flex items-center justify-between py-1.5">
+              <dt className="text-muted-foreground">{k}</dt>
+              <dd className="font-mono tabular-nums">{v}</dd>
+            </div>
+          ))}
+          <div className="mt-2 flex items-center justify-between border-t border-border pt-3">
+            <dt className="font-semibold">Payable</dt>
+            <dd className="font-mono text-base font-semibold tabular-nums">{lkr.format(payableTotal)}</dd>
+          </div>
+        </dl>
+      </section>
+
+      <div className="flex justify-end gap-3">
+        <Link href="/dashboard/sales/invoices" className={cn(buttonVariants({ variant: "outline", size: "lg" }))}>
+          Cancel
+        </Link>
+        <Button size="lg" onClick={submit} disabled={saving}>
+          <Save className="size-4" /> {saving ? "Saving..." : "Save invoice"}
+        </Button>
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/invoices/page.tsx

@@ -0,0 +1,233 @@
+"use client"
+
+import { useEffect, useMemo, useState } from "react"
+import Link from "next/link"
+import { ChevronLeft, ChevronRight, Eye, Filter, FileText, Plus, Printer } from "lucide-react"
+
+import { salesApi } from "@/lib/api/sales"
+import { errorMessage } from "@/lib/error-map"
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Badge } from "@/components/ui/badge"
+import { Input } from "@/components/ui/input"
+import { Skeleton } from "@/components/ui/skeleton"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { PaginationMeta } from "@/types/common"
+import { SalesInvoiceStatus, SalesInvoiceSummary } from "@/types/sales"
+import { cn } from "@/lib/utils"
+
+type StatusFilter = SalesInvoiceStatus | "All"
+
+const PAGE_SIZE = 10
+const tabs = ["All", "Draft", "Posted", "Cancelled"] as const
+
+function statusClass(status: SalesInvoiceStatus) {
+  switch (status) {
+    case "Draft":
+      return "border-amber-200 bg-amber-50 text-amber-800"
+    case "Posted":
+      return "border-emerald-200 bg-emerald-50 text-emerald-800"
+    case "Cancelled":
+      return "border-rose-200 bg-rose-50 text-rose-800"
+  }
+}
+
+export default function SalesInvoicesPage() {
+  const [rows, setRows] = useState<SalesInvoiceSummary[] | null>(null)
+  const [pagination, setPagination] = useState<PaginationMeta | null>(null)
+  const [error, setError] = useState<string | null>(null)
+  const [status, setStatus] = useState<StatusFilter>("All")
+  const [searchInput, setSearchInput] = useState("")
+  const [query, setQuery] = useState("")
+  const [page, setPage] = useState(1)
+
+  useEffect(() => {
+    const timeout = setTimeout(() => setQuery(searchInput.trim()), 300)
+    return () => clearTimeout(timeout)
+  }, [searchInput])
+
+  useEffect(() => setPage(1), [query, status])
+
+  useEffect(() => {
+    setError(null)
+    salesApi
+      .listInvoices({ page, pageSize: PAGE_SIZE, status: status === "All" ? undefined : status })
+      .then((res) => {
+        setRows(res.items)
+        setPagination(res.pagination)
+      })
+      .catch((err) => setError(errorMessage(err)))
+  }, [page, status])
+
+  const visibleRows = useMemo(
+    () =>
+      rows?.filter((row) =>
+        `${row.invoiceNo} ${row.customerSnapshotName}`.toLowerCase().includes(query.toLowerCase())
+      ) ?? [],
+    [rows, query]
+  )
+  const hasFilters = status !== "All" || query.length > 0
+  const grossTotal = visibleRows.reduce((sum, row) => sum + row.totals.subtotal, 0)
+  const discountTotal = visibleRows.reduce((sum, row) => sum + row.totals.discountTotal, 0)
+  const netTotal = visibleRows.reduce((sum, row) => sum + row.totals.grandTotal, 0)
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div>
+          <h1 className="text-2xl font-bold text-foreground">Sales Invoices</h1>
+          <p className="text-base text-muted-foreground">Invoice register with filters, posting flow, and settlement tracking.</p>
+        </div>
+        <div className="flex flex-wrap gap-2">
+          <Button variant="outline" size="lg">
+            <Printer className="size-5" />
+            Print batch
+          </Button>
+          <Link href="/dashboard/sales/invoices/new" className={cn(buttonVariants({ size: "lg" }))}>
+            <Plus className="size-5" />
+            New Invoice
+          </Link>
+        </div>
+      </div>
+
+      <div className="rounded-2xl border bg-card shadow-sm">
+        <div className="flex flex-col gap-3 border-b px-4 py-4 lg:flex-row lg:items-center">
+          <div className="flex flex-wrap gap-2">
+            {tabs.map((t) => (
+              <button
+                key={t}
+                onClick={() => setStatus(t)}
+                className={cn(
+                  "rounded-full border px-3 py-1.5 text-xs font-medium transition-colors",
+                  status === t ? "border-primary bg-primary text-primary-foreground" : "border-border text-muted-foreground hover:text-foreground"
+                )}
+              >
+                {t}
+              </button>
+            ))}
+          </div>
+
+          <div className="flex flex-1 flex-col gap-3 lg:flex-row lg:items-center lg:justify-end">
+            <Input
+              value={searchInput}
+              onChange={(e) => setSearchInput(e.target.value)}
+              placeholder="Filter by customer or invoice number"
+              className="h-12 w-full lg:max-w-sm"
+            />
+            <Button variant="outline" size="sm" className="lg:ml-auto">
+              <Filter className="size-4" />
+              Advanced
+            </Button>
+          </div>
+        </div>
+
+        {error && <div className="mx-4 mt-4 rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>}
+
+        {!error && rows === null && (
+          <div className="flex flex-col gap-3 px-4 py-4">
+            {Array.from({ length: 5 }).map((_, i) => (
+              <Skeleton key={i} className="h-14 w-full" />
+            ))}
+          </div>
+        )}
+
+        {!error && rows !== null && visibleRows.length === 0 && (
+          <div className="flex flex-col items-center gap-4 px-4 py-20 text-center">
+            <FileText className="size-12 text-muted-foreground" />
+            <p className="text-base text-muted-foreground">{hasFilters ? "No invoices match your filters." : "No invoices yet."}</p>
+          </div>
+        )}
+
+        {!error && rows !== null && visibleRows.length > 0 && (
+          <>
+            <div className="overflow-x-auto">
+              <Table className="text-base">
+                <TableHeader>
+                  <TableRow>
+                    <TableHead className="h-12 px-4 text-sm">Invoice</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Customer</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Date</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Due</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Lines</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Gross</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Discount</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Net</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Status</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">View</TableHead>
+                  </TableRow>
+                </TableHeader>
+                <TableBody>
+                  {visibleRows.map((row) => (
+                    <TableRow key={row.salesInvoiceId} className="hover:bg-muted/40">
+                      <TableCell className="px-4 py-3.5 font-medium">
+                        <Link href={`/dashboard/sales/invoices/${row.salesInvoiceId}`} className="hover:underline">
+                          {row.invoiceNo}
+                        </Link>
+                      </TableCell>
+                      <TableCell className="px-4 py-3.5">{row.customerSnapshotName}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-muted-foreground">{new Date(row.createdAt).toLocaleDateString()}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-muted-foreground">{new Date(row.invoiceDate).toLocaleDateString()}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums">{row.totals.freeQtyTotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums">{row.totals.subtotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums text-muted-foreground">-{row.totals.discountTotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono font-semibold tabular-nums">{row.totals.grandTotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5">
+                        <Badge variant="outline" className={statusClass(row.status)}>
+                          {row.status}
+                        </Badge>
+                      </TableCell>
+                      <TableCell className="px-4 py-3.5 text-right">
+                        <Link
+                          href={`/dashboard/sales/invoices/${row.salesInvoiceId}`}
+                          className={cn(buttonVariants({ variant: "ghost", size: "icon-sm" }))}
+                          aria-label={`View invoice ${row.invoiceNo}`}
+                        >
+                          <Eye className="size-4" />
+                        </Link>
+                      </TableCell>
+                    </TableRow>
+                  ))}
+                </TableBody>
+              </Table>
+            </div>
+
+            <div className="border-t px-4 py-3">
+              <div className="grid gap-3 text-sm md:grid-cols-3">
+                <div className="rounded-lg border bg-muted/20 px-3 py-2">
+                  <div className="text-muted-foreground">Gross total</div>
+                  <div className="font-mono text-base font-semibold tabular-nums">{grossTotal.toFixed(2)}</div>
+                </div>
+                <div className="rounded-lg border bg-muted/20 px-3 py-2">
+                  <div className="text-muted-foreground">Discount total</div>
+                  <div className="font-mono text-base font-semibold tabular-nums">-{discountTotal.toFixed(2)}</div>
+                </div>
+                <div className="rounded-lg border bg-muted/20 px-3 py-2">
+                  <div className="text-muted-foreground">Net total</div>
+                  <div className="font-mono text-base font-semibold tabular-nums">{netTotal.toFixed(2)}</div>
+                </div>
+              </div>
+            </div>
+
+            {pagination && pagination.totalPages > 1 && (
+              <div className="flex flex-col gap-3 border-t px-4 py-4 sm:flex-row sm:items-center sm:justify-between">
+                <p className="text-sm text-muted-foreground">
+                  Showing {(pagination.page - 1) * pagination.pageSize + 1}-{Math.min(pagination.page * pagination.pageSize, pagination.totalItems)} of {pagination.totalItems}
+                </p>
+                <div className="flex items-center gap-2">
+                  <Button type="button" variant="outline" size="sm" disabled={pagination.page <= 1} onClick={() => setPage((p) => Math.max(1, p - 1))}>
+                    <ChevronLeft />
+                    Previous
+                  </Button>
+                  <span className="text-sm text-muted-foreground">Page {pagination.page} of {pagination.totalPages}</span>
+                  <Button type="button" variant="outline" size="sm" disabled={pagination.page >= pagination.totalPages} onClick={() => setPage((p) => Math.min(pagination.totalPages, p + 1))}>
+                    Next
+                    <ChevronRight />
+                  </Button>
+                </div>
+              </div>
+            )}
+          </>
+        )}
+      </div>
+    </div>
+  )
+}

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

@@ -0,0 +1,73 @@
+import Link from "next/link"
+import { FileBarChart, FileText, PackageX, ReceiptText, ShoppingCart } from "lucide-react"
+
+import { buttonVariants } from "@/components/ui/button"
+import { cn } from "@/lib/utils"
+
+const sections = [
+  {
+    title: "Invoices",
+    description: "Create and manage sales invoices.",
+    href: "/dashboard/sales/invoices",
+    icon: FileText,
+  },
+  {
+    title: "Slips",
+    description: "Counter-style sales documents.",
+    href: "/dashboard/sales/slips",
+    icon: ShoppingCart,
+  },
+  {
+    title: "Free Issues",
+    description: "Promotional free-issue slips.",
+    href: "/dashboard/sales/free-issues",
+    icon: PackageX,
+  },
+  {
+    title: "Reports",
+    description: "Sales report catalog and query entry point.",
+    href: "/dashboard/sales/reports",
+    icon: FileBarChart,
+  },
+]
+
+export default function SalesHubPage() {
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex items-start justify-between gap-4">
+        <div>
+          <div className="mb-3 inline-flex items-center gap-2 rounded-full bg-primary/10 px-3 py-1 text-sm font-medium text-primary">
+            <ReceiptText className="size-4" />
+            Sales
+          </div>
+          <h1 className="text-2xl font-bold text-foreground">Sales</h1>
+          <p className="text-base text-muted-foreground">
+            Invoices, slips, free issues, and reporting in one place.
+          </p>
+        </div>
+      </div>
+
+      <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-4">
+        {sections.map((section) => {
+          const Icon = section.icon
+          return (
+            <Link
+              key={section.href}
+              href={section.href}
+              className="group rounded-2xl border bg-card p-5 shadow-sm transition-all hover:-translate-y-0.5 hover:shadow-md"
+            >
+              <div className="mb-4 flex size-11 items-center justify-center rounded-2xl bg-primary/10 text-primary">
+                <Icon className="size-5" />
+              </div>
+              <h2 className="text-lg font-semibold text-foreground">{section.title}</h2>
+              <p className="mt-1 text-sm leading-6 text-muted-foreground">{section.description}</p>
+              <div className={cn(buttonVariants({ variant: "ghost", size: "sm" }), "mt-4 px-0 text-primary")}>
+                Open
+              </div>
+            </Link>
+          )
+        })}
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/reports/[reportId]/page.tsx

@@ -0,0 +1,242 @@
+"use client"
+
+import { use, useEffect, useRef, useState } from "react"
+import Link from "next/link"
+import { ArrowLeft, FileBarChart } from "lucide-react"
+
+import { salesApi } from "@/lib/api/sales"
+import { errorMessage } from "@/lib/error-map"
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card"
+import { Input } from "@/components/ui/input"
+import { Skeleton } from "@/components/ui/skeleton"
+import { SalesReportDefinition } from "@/types/sales"
+
+function formatHeader(key: string) {
+  return key
+    .replace(/([a-z0-9])([A-Z])/g, "$1 $2")
+    .replace(/([A-Z]+)([A-Z][a-z])/g, "$1 $2")
+    .replace(/_/g, " ")
+    .trim()
+}
+
+function formatCell(value: unknown) {
+  if (value === null || value === undefined) return ""
+  if (typeof value === "number") return value.toLocaleString("en-LK", { maximumFractionDigits: 2 })
+  if (typeof value === "string") {
+    const isoDate = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/.test(value) || /^\d{4}-\d{2}-\d{2}$/.test(value)
+    if (isoDate) {
+      const parsed = new Date(value)
+      if (!Number.isNaN(parsed.getTime())) {
+        return new Intl.DateTimeFormat("en-LK", {
+          year: "numeric",
+          month: "short",
+          day: "2-digit",
+        }).format(parsed)
+      }
+    }
+    return value
+  }
+  if (typeof value === "boolean") return value ? "Yes" : "No"
+  if (Array.isArray(value)) return value.map((item) => formatCell(item)).join(", ")
+  if (typeof value === "object") return JSON.stringify(value)
+  return String(value)
+}
+
+const reportColumns: Record<string, string[]> = {
+  "daily-summary": ["date", "invoiceCount", "slipCount", "invoiceSubtotal", "slipSubtotal", "discountTotal", "freeQtyTotal", "taxTotal", "grandTotal"],
+  "item-summary": ["itemId", "itemName", "soldQty", "freeQty", "grossAmount", "discountTotal", "taxTotal", "netAmount"],
+  "customer-summary": ["customerId", "customerName", "invoiceCount", "slipCount", "soldQty", "freeQty", "grossAmount", "discountTotal", "taxTotal", "netAmount"],
+  "warehouse-summary": ["warehouseId", "warehouseName", "invoiceCount", "slipCount", "soldQty", "freeQty", "grossAmount", "discountTotal", "taxTotal", "netAmount"],
+  "discount-summary": ["documentType", "documentNo", "documentDate", "customerName", "subtotal", "discountTotal", "taxTotal", "netAmount"],
+  "free-issue-summary": ["documentType", "documentNo", "documentDate", "customerName", "itemId", "itemName", "freeQty", "freeValue", "warehouseId", "warehouseName"],
+}
+
+export default function SalesReportDetailPage({ params }: { params: Promise<{ reportId: string }> }) {
+  const resolvedParams = use(params)
+  const [report, setReport] = useState<SalesReportDefinition | null>(null)
+  const [error, setError] = useState<string | null>(null)
+  const [loading, setLoading] = useState(true)
+  const [from, setFrom] = useState("")
+  const [to, setTo] = useState("")
+  const [queryLoading, setQueryLoading] = useState(false)
+  const [rows, setRows] = useState<unknown[] | null>(null)
+  const [queryError, setQueryError] = useState<string | null>(null)
+  const lastAutoRunKey = useRef<string>("")
+
+  useEffect(() => {
+    setError(null)
+    setLoading(true)
+    salesApi.getReport(resolvedParams.reportId)
+      .then(setReport)
+      .catch((err) => setError(errorMessage(err)))
+      .finally(() => setLoading(false))
+  }, [resolvedParams.reportId])
+
+  useEffect(() => {
+    const now = new Date()
+    const firstDay = new Date(now.getFullYear(), now.getMonth(), 1)
+    setFrom(firstDay.toISOString().slice(0, 10))
+    setTo(now.toISOString().slice(0, 10))
+  }, [resolvedParams.reportId])
+
+  useEffect(() => {
+    if (!report || !from || !to) return
+
+    const runKey = `${report.id}:${from}:${to}`
+    if (lastAutoRunKey.current === runKey) return
+
+    lastAutoRunKey.current = runKey
+    setQueryError(null)
+    setQueryLoading(true)
+    salesApi
+      .queryReport({
+        reportType: report.id,
+        from,
+        to,
+      })
+      .then((response) => setRows(response.rows))
+      .catch((err) => {
+        setRows(null)
+        setQueryError(errorMessage(err))
+      })
+      .finally(() => setQueryLoading(false))
+  }, [report, from, to])
+
+  const runReport = () => {
+    if (!report) return
+    if (!from || !to) {
+      setQueryError("Select both from and to dates.")
+      setRows(null)
+      return
+    }
+
+    lastAutoRunKey.current = `${report.id}:${from}:${to}`
+    setQueryError(null)
+    setQueryLoading(true)
+    salesApi
+      .queryReport({
+        reportType: report.id,
+        from,
+        to,
+      })
+      .then((response) => setRows(response.rows))
+      .catch((err) => {
+        setRows(null)
+        setQueryError(errorMessage(err))
+      })
+      .finally(() => setQueryLoading(false))
+  }
+
+  const columns = report ? (reportColumns[report.id] ?? (rows && rows.length > 0 ? Object.keys(rows[0] as Record<string, unknown>) : [])) : []
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex items-center gap-3">
+        <Link href="/dashboard/sales/reports" className={buttonVariants({ variant: "outline", size: "icon" })}>
+          <ArrowLeft className="size-4" />
+        </Link>
+        <div>
+          <h1 className="text-2xl font-bold text-foreground">Report Details</h1>
+          <p className="text-base text-muted-foreground">Metadata for the selected sales report.</p>
+        </div>
+      </div>
+
+      {error && <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>}
+
+      {!error && loading && <Skeleton className="h-48 rounded-2xl" />}
+
+      {!error && !loading && report === null && (
+        <div className="rounded-2xl border border-dashed p-8 text-base text-muted-foreground">
+          Report metadata could not be loaded. The report id may be invalid, or your session may have expired.
+        </div>
+      )}
+
+      {!error && report && (
+        <div className="space-y-4">
+          <Card>
+            <CardHeader>
+              <div className="flex items-center gap-3">
+                <div className="flex size-11 items-center justify-center rounded-xl bg-primary/10 text-primary">
+                  <FileBarChart className="size-5" />
+                </div>
+                <div>
+                  <CardTitle className="text-lg">{report.name}</CardTitle>
+                  <p className="mt-1 text-sm text-muted-foreground">{report.id}</p>
+                </div>
+              </div>
+            </CardHeader>
+            <CardContent>
+              <p className="text-base text-muted-foreground">{report.description}</p>
+            </CardContent>
+          </Card>
+
+          {resolvedParams.reportId !== "daily-summary" && (
+          <Card>
+            <CardContent className="grid gap-4 p-4 sm:grid-cols-2 lg:grid-cols-3">
+              <div className="space-y-2">
+                <label className="text-sm font-medium text-foreground">From</label>
+                <Input type="date" value={from} onChange={(e) => setFrom(e.target.value)} />
+                </div>
+                <div className="space-y-2">
+                  <label className="text-sm font-medium text-foreground">To</label>
+                  <Input type="date" value={to} onChange={(e) => setTo(e.target.value)} />
+              </div>
+              <div className="flex items-end">
+                <Button type="button" className="w-full sm:w-auto" onClick={runReport} disabled={queryLoading}>
+                  Run report
+                </Button>
+                </div>
+              </CardContent>
+            </Card>
+          )}
+
+          {queryError && <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{queryError}</div>}
+
+          {queryLoading && <Skeleton className="h-40 rounded-2xl" />}
+
+          {!queryLoading && rows && rows.length === 0 && (
+            <div className="rounded-lg border border-dashed p-8 text-sm text-muted-foreground">
+              No rows returned for the selected date range.
+            </div>
+          )}
+
+          {!queryLoading && rows && rows.length > 0 && (
+            <Card>
+              <CardHeader>
+                <CardTitle className="text-base">Report Results</CardTitle>
+              </CardHeader>
+              <CardContent className="overflow-x-auto">
+                <table className="w-full text-sm">
+                  <thead className="bg-secondary/60 text-[11px] uppercase tracking-wide text-muted-foreground">
+                    <tr>
+                      {columns.map((key) => (
+                        <th key={key} className="px-4 py-2 text-left font-medium">
+                          {formatHeader(key)}
+                        </th>
+                      ))}
+                    </tr>
+                  </thead>
+                  <tbody>
+                    {rows.map((row, index) => {
+                      const record = row as Record<string, unknown>
+                      return (
+                        <tr key={index} className="border-t border-border hover:bg-secondary/40">
+                          {columns.map((key) => (
+                            <td key={key} className="px-4 py-2.5 align-top">
+                              {formatCell(record[key])}
+                            </td>
+                          ))}
+                        </tr>
+                      )
+                    })}
+                  </tbody>
+                </table>
+              </CardContent>
+            </Card>
+          )}
+        </div>
+      )}
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/reports/page.tsx

@@ -0,0 +1,81 @@
+"use client"
+
+import { useEffect, useState } from "react"
+import Link from "next/link"
+import { BarChart3, CalendarRange, FileBarChart, ShoppingCart, type LucideIcon } from "lucide-react"
+
+import { salesApi } from "@/lib/api/sales"
+import { errorMessage } from "@/lib/error-map"
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card"
+import { Skeleton } from "@/components/ui/skeleton"
+import { SalesReportDefinition } from "@/types/sales"
+
+const reportIcons: Record<string, LucideIcon> = {
+  sales: BarChart3,
+  invoice: FileBarChart,
+  product: ShoppingCart,
+  period: CalendarRange,
+}
+
+export default function SalesReportsPage() {
+  const [reports, setReports] = useState<SalesReportDefinition[] | null>(null)
+  const [error, setError] = useState<string | null>(null)
+
+  useEffect(() => {
+    setError(null)
+    salesApi.listReports().then(setReports).catch((err) => setError(errorMessage(err)))
+  }, [])
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div>
+        <h1 className="text-2xl font-bold text-foreground">Sales Reports</h1>
+        <p className="text-base text-muted-foreground">
+          Card-based report hub with the same layout and handling style used across stock management.
+        </p>
+      </div>
+
+      {error && <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>}
+
+      {!error && reports === null && (
+        <div className="grid grid-cols-1 gap-4 sm:grid-cols-2 xl:grid-cols-3">
+          {Array.from({ length: 6 }).map((_, i) => (
+            <Skeleton key={i} className="h-40 rounded-xl" />
+          ))}
+        </div>
+      )}
+
+      {!error && reports && reports.length === 0 && (
+        <div className="flex flex-col items-center gap-4 rounded-xl border border-dashed py-20 text-center">
+          <FileBarChart className="size-12 text-muted-foreground" />
+          <p className="text-base text-muted-foreground">No sales reports are available.</p>
+        </div>
+      )}
+
+      {!error && reports && reports.length > 0 && (
+        <div className="grid grid-cols-1 gap-4 sm:grid-cols-2 xl:grid-cols-3">
+          {reports.map((report) => (
+            <Link key={report.id} href={`/dashboard/sales/reports/${report.id}`}>
+              <Card className="h-full transition-shadow group-hover:shadow-md">
+                <CardHeader>
+                  <div className="flex items-center gap-3">
+                    <div className="flex size-11 shrink-0 items-center justify-center rounded-xl bg-primary/10 text-primary">
+                      {(() => {
+                        const Icon = reportIcons[report.id.toLowerCase()] ?? FileBarChart
+                        return <Icon className="size-5" />
+                      })()}
+                    </div>
+                    <CardTitle className="text-lg">{report.name}</CardTitle>
+                  </div>
+                </CardHeader>
+                <CardContent>
+                  <p className="text-base text-muted-foreground">{report.description}</p>
+                </CardContent>
+              </Card>
+            </Link>
+          ))}
+        </div>
+      )}
+    </div>
+  )
+}

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

@@ -0,0 +1,456 @@
+"use client"
+
+import { use, useEffect, useMemo, useState } from "react"
+import Link from "next/link"
+import { ArrowLeft, Minus, Plus, Save, Send, X } from "lucide-react"
+
+import { salesApi } from "@/lib/api/sales"
+import { customersApi } from "@/lib/api/customers"
+import { itemsApi } from "@/lib/api/items"
+import { uomsApi } from "@/lib/api/uoms"
+import { warehousesApi } from "@/lib/api/warehouses"
+import { usersApi } from "@/lib/api/users"
+import { errorMessage } from "@/lib/error-map"
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Label } from "@/components/ui/label"
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select"
+import { Skeleton } from "@/components/ui/skeleton"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { cn } from "@/lib/utils"
+import { getSuggestedUnitPrice } from "@/lib/sales-line-utils"
+import { FreeIssuePromotionSuggestions } from "@/components/sales/FreeIssuePromotionSuggestions"
+import { Customer } from "@/types/customers"
+import { ItemListItem, Uom, Warehouse } from "@/types/master-data"
+import { ManagedUser } from "@/types/users"
+import { CreateSalesSlipLineRequest, SalesFreeIssueSuggestion, SalesSlip, SalesSlipPostingCheck } from "@/types/sales"
+import { toast } from "@/components/ui/toast"
+
+type Line = CreateSalesSlipLineRequest & { key: string }
+
+const money = new Intl.NumberFormat("en-LK", {
+  style: "currency",
+  currency: "LKR",
+  minimumFractionDigits: 2,
+})
+
+const blankLine = (key: string): Line => ({
+  key,
+  itemId: 0,
+  uomId: 0,
+  warehouseId: 0,
+  qty: 1,
+  freeQty: 0,
+  unitPrice: null,
+  allowManualPriceOverride: true,
+  discountMode: "Percentage",
+  discountPct: 0,
+  discountAmount: 0,
+  discountValue: 0,
+  taxPct: 0,
+  isFreeIssue: false,
+  parentLineId: null,
+})
+
+export default function SalesSlipDetailPage({ params }: { params: Promise<{ id: string }> }) {
+  const resolvedParams = use(params)
+  const slipId = Number(resolvedParams.id)
+  const [slip, setSlip] = useState<SalesSlip | null>(null)
+  const [etag, setEtag] = useState<string | null>(null)
+  const [customers, setCustomers] = useState<Customer[]>([])
+  const [items, setItems] = useState<ItemListItem[]>([])
+  const [uoms, setUoms] = useState<Uom[]>([])
+  const [warehouses, setWarehouses] = useState<Warehouse[]>([])
+  const [users, setUsers] = useState<ManagedUser[]>([])
+  const [promotionSuggestion, setPromotionSuggestion] = useState<SalesFreeIssueSuggestion | null>(null)
+  const [postingCheck, setPostingCheck] = useState<SalesSlipPostingCheck | null>(null)
+  const [customerId, setCustomerId] = useState<number | null>(null)
+  const [warehouseId, setWarehouseId] = useState<number | null>(null)
+  const [cashierUserId, setCashierUserId] = useState<number | null>(null)
+  const [lines, setLines] = useState<Line[]>([blankLine("line-1")])
+  const [error, setError] = useState<string | null>(null)
+  const [saving, setSaving] = useState(false)
+  const [actionBusy, setActionBusy] = useState<"post" | "cancel" | null>(null)
+
+  useEffect(() => {
+    if (!Number.isFinite(slipId)) {
+      setError(`Invalid slip id '${resolvedParams.id}'.`)
+      return
+    }
+    Promise.all([
+      customersApi.list({ pageSize: 200 }),
+      itemsApi.list({ pageSize: 200 }),
+      uomsApi.list({ pageSize: 200 }),
+      warehousesApi.list({ pageSize: 200 }),
+      usersApi.list({ pageSize: 200 }),
+      salesApi.getSlip(slipId),
+    ])
+      .then(([cust, itemRes, uomRes, whRes, userRes, doc]) => {
+        setCustomers(cust.items)
+        setItems(itemRes.items)
+        setUoms(uomRes.items)
+        setWarehouses(whRes.items)
+        setUsers(userRes.items)
+        setSlip(doc.data)
+        setEtag(doc.etag)
+        setCustomerId(doc.data.customerId)
+        setWarehouseId(doc.data.warehouseId)
+        setCashierUserId(doc.data.cashierUserId)
+        setPromotionSuggestion(null)
+        setLines(
+          doc.data.lines.map((line) => ({
+            key: String(line.salesSlipLineId),
+            itemId: line.itemId,
+            uomId: line.uomId,
+            warehouseId: line.warehouseId,
+            qty: line.qty,
+            freeQty: line.freeQty,
+            unitPrice: line.unitPrice,
+            allowManualPriceOverride: true,
+            discountMode: line.discountMode,
+            discountPct: line.discountPct,
+            discountAmount: line.discountAmount,
+            discountValue: 0,
+            taxPct: line.taxPct,
+            isFreeIssue: line.isFreeIssue,
+            parentLineId: line.parentLineId,
+          }))
+        )
+      })
+      .then(async () => {
+        try {
+          const suggestions = await salesApi.getFreeIssueSuggestions(slipId)
+          setPromotionSuggestion(suggestions)
+        } catch {
+          setPromotionSuggestion(null)
+        }
+      })
+      .catch((err) => setError(errorMessage(err)))
+  }, [resolvedParams.id, slipId])
+
+  useEffect(() => {
+    if (!slip || slip.status !== "Draft") {
+      setPostingCheck(null)
+      return
+    }
+    salesApi
+      .checkSlipPosting(slipId)
+      .then((result) => setPostingCheck(result))
+      .catch(() => setPostingCheck(null))
+  }, [slip, slipId])
+
+  const subtotal = useMemo(
+    () => lines.reduce((sum, line) => sum + Number(line.qty || 0) * Number(line.unitPrice ?? 0), 0),
+    [lines]
+  )
+
+  function updateLine(key: string, patch: Partial<Line>) {
+    setLines((prev) => prev.map((line) => (line.key === key ? { ...line, ...patch } : line)))
+  }
+
+  function selectItem(key: string, itemId: number) {
+    updateLine(key, {
+      itemId,
+      unitPrice: getSuggestedUnitPrice(items, itemId),
+    })
+  }
+
+  function addLine() {
+    setLines((prev) => [...prev, blankLine(`line-${Date.now()}`)])
+  }
+
+  function removeLine(key: string) {
+    setLines((prev) => (prev.length === 1 ? prev : prev.filter((line) => line.key !== key)))
+  }
+
+  async function save() {
+    if (!customerId || !warehouseId || !cashierUserId || !etag) return
+    setSaving(true)
+    setError(null)
+    try {
+      const payload = {
+        customerId,
+        warehouseId,
+        cashierUserId,
+        lines: lines.map((line) => ({
+          itemId: Number(line.itemId),
+          uomId: Number(line.uomId),
+          warehouseId: Number(line.warehouseId),
+          qty: Number(line.qty),
+          freeQty: Number(line.freeQty),
+          unitPrice: line.unitPrice === null ? null : Number(line.unitPrice),
+          allowManualPriceOverride: line.allowManualPriceOverride,
+          discountMode: line.discountMode,
+          discountPct: Number(line.discountPct),
+          discountAmount: Number(line.discountAmount),
+          discountValue: Number(line.discountValue),
+          taxPct: Number(line.taxPct),
+          isFreeIssue: line.isFreeIssue,
+          parentLineId: line.parentLineId || null,
+        })),
+      }
+      const updated = await salesApi.updateSlip(slipId, payload, etag)
+      setSlip(updated.data)
+      setEtag(updated.etag)
+      toast.success("Slip saved", updated.data.slipNo)
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  async function post() {
+    if (!postingCheck?.canPost) {
+      setError("Resolve stock shortages before posting this slip.")
+      return
+    }
+    setActionBusy("post")
+    setError(null)
+    try {
+      const posted = await salesApi.postSlip(slipId)
+      setSlip(posted)
+      toast.success("Slip posted", posted.slipNo)
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setActionBusy(null)
+    }
+  }
+
+  async function cancel() {
+    setActionBusy("cancel")
+    setError(null)
+    try {
+      const cancelled = await salesApi.cancelSlip(slipId)
+      setSlip(cancelled)
+      toast.success("Slip cancelled", cancelled.slipNo)
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setActionBusy(null)
+    }
+  }
+
+  if (error && !slip) return <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>
+  if (!slip) return <div className="rounded-2xl border border-dashed p-8 text-muted-foreground">{error ?? "Slip data is loading or unavailable."}</div>
+
+  const locked = slip.status !== "Draft"
+  const canPost = slip.status === "Draft" && (postingCheck?.canPost ?? true) && actionBusy === null
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex items-center justify-between gap-3">
+        <div className="flex items-center gap-3">
+          <Link href="/dashboard/sales/slips" className={cn(buttonVariants({ variant: "outline", size: "icon" }))}>
+            <ArrowLeft className="size-4" />
+          </Link>
+          <div>
+            <h1 className="text-2xl font-bold text-foreground">Sales Slip</h1>
+            <p className="text-base text-muted-foreground">{slip.slipNo} · {slip.status}</p>
+          </div>
+        </div>
+        <div className="flex flex-wrap gap-2">
+          <Button variant="outline" onClick={save} disabled={saving || locked}><Save className="size-4" />{saving ? "Saving..." : "Save"}</Button>
+          <Button variant="outline" onClick={post} disabled={!canPost}><Send className="size-4" />{postingCheck && !postingCheck.canPost ? "Resolve shortages first" : actionBusy === "post" ? "Posting..." : "Post"}</Button>
+          <Button variant="destructive" onClick={cancel} disabled={actionBusy !== null || locked}><X className="size-4" />{actionBusy === "cancel" ? "Cancelling..." : "Cancel"}</Button>
+        </div>
+      </div>
+
+      {error && <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>}
+
+      <section className="bg-white">
+        <div className="border-b pb-4">
+          <div className="flex flex-col gap-3 md:flex-row md:items-start md:justify-between">
+            <div>
+              <div className="text-xs font-semibold uppercase tracking-[0.35em] text-muted-foreground">Sales Slip</div>
+              <h2 className="mt-2 text-3xl font-semibold text-foreground">{slip.slipNo}</h2>
+              <div className="mt-1 flex flex-wrap items-center gap-2 text-sm text-muted-foreground">
+                <span>Status:</span>
+                <span className={cn("inline-flex rounded-full border px-2 py-0.5 text-xs font-medium", slip.status === "Draft" ? "border-amber-200 bg-amber-50 text-amber-800" : slip.status === "Posted" ? "border-emerald-200 bg-emerald-50 text-emerald-800" : "border-rose-200 bg-rose-50 text-rose-800")}>
+                  {slip.status}
+                </span>
+                <span>Date: {new Date(slip.slipDate).toLocaleDateString()}</span>
+                <span>Cashier: {users.find((u) => u.userId === slip.cashierUserId)?.displayName ?? `#${slip.cashierUserId}`}</span>
+              </div>
+            </div>
+            <div className="text-sm md:text-right">
+              <div className="font-semibold text-foreground">{customers.find((c) => c.customerId === slip.customerId)?.displayName ?? customers.find((c) => c.customerId === slip.customerId)?.name ?? slip.customerSnapshotName}</div>
+              <div className="text-muted-foreground">Warehouse: {warehouses.find((w) => w.warehouseId === slip.warehouseId)?.name ?? `#${slip.warehouseId}`}</div>
+              <div className="text-muted-foreground">Code: {warehouses.find((w) => w.warehouseId === slip.warehouseId)?.code ?? slip.warehouseId}</div>
+            </div>
+          </div>
+        </div>
+
+        <div className="grid gap-6 py-5 md:grid-cols-3">
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Customer</div>
+            <div className="mt-2 font-semibold text-foreground">{slip.customerSnapshotName}</div>
+            <div className="text-sm text-muted-foreground">Customer ID: {slip.customerId}</div>
+          </div>
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Warehouse</div>
+            <div className="mt-2 font-semibold text-foreground">{warehouses.find((w) => w.warehouseId === slip.warehouseId)?.name ?? `#${slip.warehouseId}`}</div>
+            <div className="text-sm text-muted-foreground">Code: {warehouses.find((w) => w.warehouseId === slip.warehouseId)?.code ?? slip.warehouseId}</div>
+          </div>
+          <div>
+            <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Totals</div>
+            <div className="mt-2 grid grid-cols-2 gap-2 text-sm">
+              <div className="text-muted-foreground">Subtotal</div>
+              <div className="text-right font-medium">{money.format(slip.totals.subtotal)}</div>
+              <div className="text-muted-foreground">Discount</div>
+              <div className="text-right font-medium">{money.format(slip.totals.discountTotal)}</div>
+              <div className="text-muted-foreground">Free qty</div>
+              <div className="text-right font-medium">{slip.totals.freeQtyTotal.toFixed(0)}</div>
+              <div className="text-muted-foreground">Grand total</div>
+              <div className="text-right font-semibold">{money.format(slip.totals.grandTotal)}</div>
+            </div>
+          </div>
+        </div>
+
+        <div className="overflow-x-auto border-y">
+          <Table className="text-sm">
+            <TableHeader>
+              <TableRow>
+                <TableHead className="h-12 px-4 text-sm">Item</TableHead>
+                <TableHead className="h-12 px-4 text-sm">UOM</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Qty</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Free</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Unit price</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Line total</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {slip.lines.map((line) => (
+                <TableRow key={line.salesSlipLineId}>
+                  <TableCell className="px-4 py-3">
+                    <div className="font-medium text-foreground">{line.description}</div>
+                    <div className="text-xs text-muted-foreground">SKU {items.find((i) => i.itemId === line.itemId)?.sku ?? `#${line.itemId}`}</div>
+                  </TableCell>
+                  <TableCell className="px-4 py-3">{uoms.find((u) => u.uomId === line.uomId)?.name ?? `#${line.uomId}`}</TableCell>
+                  <TableCell className="px-4 py-3 text-right">{line.qty.toFixed(0)}</TableCell>
+                  <TableCell className="px-4 py-3 text-right">{line.freeQty > 0 ? line.freeQty.toFixed(0) : "—"}</TableCell>
+                  <TableCell className="px-4 py-3 text-right">{money.format(line.unitPrice)}</TableCell>
+                  <TableCell className="px-4 py-3 text-right font-medium">{money.format(line.lineTotal)}</TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </div>
+      </section>
+
+      {slip.status === "Draft" && postingCheck && !postingCheck.canPost ? (
+        <div className="rounded-lg border border-amber-200 bg-amber-50 p-4 text-sm text-amber-900">
+          <div className="font-semibold">Stock shortage detected before posting</div>
+          <div className="mt-1">This slip cannot be posted until every line has enough available stock in the selected warehouse.</div>
+          <div className="mt-3 overflow-x-auto">
+            <table className="w-full text-sm">
+              <thead className="text-left text-xs uppercase tracking-wide text-amber-900/70">
+                <tr>
+                  <th className="py-1 pr-3">Item</th>
+                  <th className="py-1 pr-3">Warehouse</th>
+                  <th className="py-1 pr-3 text-right">Requested</th>
+                  <th className="py-1 pr-3 text-right">Available</th>
+                  <th className="py-1 text-right">Short</th>
+                </tr>
+              </thead>
+              <tbody>
+                {postingCheck.issues.map((issue) => (
+                  <tr key={issue.salesSlipLineId} className="border-t border-amber-200/60">
+                    <td className="py-2 pr-3">
+                      <div className="font-medium">{issue.itemSku}</div>
+                      <div className="text-xs text-amber-900/70">{issue.itemName}{issue.isFreeIssue ? " · free issue" : ""}</div>
+                    </td>
+                    <td className="py-2 pr-3">{issue.warehouseId}</td>
+                    <td className="py-2 pr-3 text-right font-mono tabular-nums">{issue.requestedQty.toFixed(0)}</td>
+                    <td className="py-2 pr-3 text-right font-mono tabular-nums">{issue.availableQty.toFixed(0)}</td>
+                    <td className="py-2 text-right font-mono tabular-nums">{issue.shortQty.toFixed(0)}</td>
+                  </tr>
+                ))}
+              </tbody>
+            </table>
+          </div>
+        </div>
+      ) : null}
+
+      {slip.status === "Draft" ? (
+        <>
+          <div className="grid gap-4 md:grid-cols-3">
+            <div className="flex flex-col gap-2">
+              <Label>Customer</Label>
+              <Select value={customerId ? String(customerId) : ""} onValueChange={(v) => setCustomerId(v ? Number(v) : null)} disabled={locked}>
+                <SelectTrigger className="h-12!"><SelectValue /></SelectTrigger>
+                <SelectContent>{customers.map((c) => <SelectItem key={c.customerId} value={String(c.customerId)}>{c.customerCode} - {c.displayName ?? c.name}</SelectItem>)}</SelectContent>
+              </Select>
+            </div>
+            <div className="flex flex-col gap-2">
+              <Label>Warehouse</Label>
+              <Select value={warehouseId ? String(warehouseId) : ""} onValueChange={(v) => setWarehouseId(v ? Number(v) : null)} disabled={locked}>
+                <SelectTrigger className="h-12!"><SelectValue /></SelectTrigger>
+                <SelectContent>{warehouses.map((w) => <SelectItem key={w.warehouseId} value={String(w.warehouseId)}>{w.code} - {w.name}</SelectItem>)}</SelectContent>
+              </Select>
+            </div>
+            <div className="flex flex-col gap-2">
+              <Label>Cashier</Label>
+              <Select value={cashierUserId ? String(cashierUserId) : ""} onValueChange={(v) => setCashierUserId(v ? Number(v) : null)} disabled={locked}>
+                <SelectTrigger className="h-12!"><SelectValue /></SelectTrigger>
+                <SelectContent>{users.map((u) => <SelectItem key={u.userId} value={String(u.userId)}>{u.displayName}</SelectItem>)}</SelectContent>
+              </Select>
+            </div>
+          </div>
+
+          <div className="rounded-2xl border p-4">
+            <div className="mb-3 flex items-center justify-between">
+              <h2 className="text-lg font-semibold">Lines</h2>
+              <Button type="button" variant="outline" onClick={addLine} disabled={locked}><Plus className="size-4" /> Add line</Button>
+            </div>
+            <Table>
+              <TableHeader>
+                <TableRow>
+                  <TableHead>Item</TableHead>
+                  <TableHead>UOM</TableHead>
+                  <TableHead>Qty</TableHead>
+                  <TableHead>Free</TableHead>
+                  <TableHead>Unit price</TableHead>
+                  <TableHead />
+                </TableRow>
+              </TableHeader>
+              <TableBody>
+                {lines.map((line) => (
+                  <TableRow key={line.key}>
+                    <TableCell>
+                      <Select value={line.itemId ? String(line.itemId) : ""} onValueChange={(v) => selectItem(line.key, Number(v))} disabled={locked}>
+                        <SelectTrigger className="h-11!"><SelectValue placeholder="Item" /></SelectTrigger>
+                        <SelectContent>{items.map((i) => <SelectItem key={i.itemId} value={String(i.itemId)}>{i.sku} - {i.name}</SelectItem>)}</SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell>
+                      <Select value={line.uomId ? String(line.uomId) : ""} onValueChange={(v) => updateLine(line.key, { uomId: Number(v) })} disabled={locked}>
+                        <SelectTrigger className="h-11!"><SelectValue placeholder="UOM" /></SelectTrigger>
+                        <SelectContent>{uoms.map((u) => <SelectItem key={u.uomId} value={String(u.uomId)}>{u.name}</SelectItem>)}</SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell><Input type="number" min="0" step="0.01" value={line.qty} onChange={(e) => updateLine(line.key, { qty: Number(e.target.value) })} disabled={locked} /></TableCell>
+                    <TableCell><Input type="number" min="0" step="0.01" value={line.freeQty} onChange={(e) => updateLine(line.key, { freeQty: Number(e.target.value) })} disabled={locked} /></TableCell>
+                    <TableCell><Input type="number" min="0" step="0.01" value={line.unitPrice ?? ""} onChange={(e) => updateLine(line.key, { unitPrice: e.target.value === "" ? null : Number(e.target.value) })} disabled={locked} /></TableCell>
+                    <TableCell><Button type="button" variant="ghost" size="icon" onClick={() => removeLine(line.key)} disabled={locked}><Minus className="size-4" /></Button></TableCell>
+                  </TableRow>
+                ))}
+              </TableBody>
+            </Table>
+            <div className="mt-4 text-sm text-muted-foreground">Subtotal: {subtotal.toFixed(2)}</div>
+          </div>
+
+          <FreeIssuePromotionSuggestions suggestion={promotionSuggestion} />
+
+          <div className="flex justify-end gap-3">
+            <Link href="/dashboard/sales/slips" className={cn(buttonVariants({ variant: "outline", size: "lg" }))}>Back</Link>
+            <Button variant="outline" onClick={save} disabled={saving || locked}>Save</Button>
+            <Button onClick={post} disabled={!canPost}>Post</Button>
+          </div>
+        </>
+      ) : null}
+    </div>
+  )
+}
+

Frontend/erp-system/app/dashboard/sales/slips/new/page.tsx

@@ -0,0 +1,440 @@
+"use client"
+
+import { useEffect, useMemo, useState } from "react"
+import { useRouter } from "next/navigation"
+import Link from "next/link"
+import { ArrowLeft, Minus, Plus, Save, Trash2 } from "lucide-react"
+
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Label } from "@/components/ui/label"
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select"
+import { Badge } from "@/components/ui/badge"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { cn } from "@/lib/utils"
+import { getSuggestedUnitPrice } from "@/lib/sales-line-utils"
+import { errorMessage } from "@/lib/error-map"
+import { salesApi } from "@/lib/api/sales"
+import { customersApi } from "@/lib/api/customers"
+import { itemsApi } from "@/lib/api/items"
+import { uomsApi } from "@/lib/api/uoms"
+import { warehousesApi } from "@/lib/api/warehouses"
+import { usersApi } from "@/lib/api/users"
+import { Customer } from "@/types/customers"
+import { ItemListItem, Uom, Warehouse } from "@/types/master-data"
+import { ManagedUser } from "@/types/users"
+import { CreateSalesSlipLineRequest, CreateSalesSlipRequest } from "@/types/sales"
+import { toast } from "@/components/ui/toast"
+
+type Line = CreateSalesSlipLineRequest & { key: string }
+
+const blankLine = (key: string): Line => ({
+  key,
+  itemId: 0,
+  uomId: 0,
+  warehouseId: 0,
+  qty: 1,
+  freeQty: 0,
+  unitPrice: null,
+  allowManualPriceOverride: true,
+  discountMode: "Percentage",
+  discountPct: 0,
+  discountAmount: 0,
+  discountValue: 0,
+  taxPct: 0,
+  isFreeIssue: false,
+  parentLineId: null,
+})
+
+const lkr = new Intl.NumberFormat("en-LK", {
+  style: "currency",
+  currency: "LKR",
+  minimumFractionDigits: 2,
+})
+
+export default function NewSalesSlipPage() {
+  const router = useRouter()
+  const [customers, setCustomers] = useState<Customer[]>([])
+  const [items, setItems] = useState<ItemListItem[]>([])
+  const [uoms, setUoms] = useState<Uom[]>([])
+  const [warehouses, setWarehouses] = useState<Warehouse[]>([])
+  const [users, setUsers] = useState<ManagedUser[]>([])
+  const [customerId, setCustomerId] = useState<number | null>(null)
+  const [warehouseId, setWarehouseId] = useState<number | null>(null)
+  const [cashierUserId, setCashierUserId] = useState<number | null>(null)
+  const [lines, setLines] = useState<Line[]>([blankLine("line-1")])
+  const [loading, setLoading] = useState(true)
+  const [submitError, setSubmitError] = useState<string | null>(null)
+  const [saving, setSaving] = useState(false)
+
+  useEffect(() => {
+    Promise.all([
+      customersApi.list({ pageSize: 200 }),
+      itemsApi.list({ pageSize: 200 }),
+      uomsApi.list({ pageSize: 200 }),
+      warehousesApi.list({ pageSize: 200 }),
+      usersApi.list({ pageSize: 200 }),
+    ])
+      .then(([cust, itemRes, uomRes, whRes, userRes]) => {
+        setCustomers(cust.items)
+        setItems(itemRes.items)
+        setUoms(uomRes.items)
+        setWarehouses(whRes.items)
+        setUsers(userRes.items)
+        setCustomerId(cust.items[0]?.customerId ?? null)
+        setWarehouseId(whRes.items[0]?.warehouseId ?? null)
+        setCashierUserId(userRes.items[0]?.userId ?? null)
+        setLines([
+          {
+            ...blankLine("line-1"),
+            itemId: itemRes.items[0]?.itemId ?? 0,
+            uomId: itemRes.items[0]?.baseUomId ?? uomRes.items[0]?.uomId ?? 0,
+            warehouseId: whRes.items[0]?.warehouseId ?? 0,
+            unitPrice: getSuggestedUnitPrice(itemRes.items, itemRes.items[0]?.itemId),
+          },
+        ])
+      })
+      .catch((err) => setSubmitError(errorMessage(err)))
+      .finally(() => setLoading(false))
+  }, [])
+
+  function updateLine(key: string, patch: Partial<Line>) {
+    setLines((prev) => prev.map((line) => (line.key === key ? { ...line, ...patch } : line)))
+  }
+
+  function selectItem(key: string, itemId: number) {
+    const item = items.find((candidate) => candidate.itemId === itemId)
+    updateLine(key, {
+      itemId,
+      uomId: item?.baseUomId ?? 0,
+      unitPrice: getSuggestedUnitPrice(items, itemId),
+    })
+  }
+
+  function addLine() {
+    setLines((prev) => [...prev, blankLine(`line-${Date.now()}`)])
+  }
+
+  function removeLine(key: string) {
+    setLines((prev) => (prev.length === 1 ? prev : prev.filter((line) => line.key !== key)))
+  }
+
+  const grossTotal = useMemo(
+    () => lines.reduce((sum, line) => sum + Number(line.unitPrice ?? 0) * Number(line.qty || 0), 0),
+    [lines],
+  )
+  const discountTotal = useMemo(
+    () =>
+      lines.reduce((sum, line) => {
+        const gross = Number(line.unitPrice ?? 0) * Number(line.qty || 0)
+        const mode = String(line.discountMode)
+        return sum + (mode === "Amount" ? Number(line.discountAmount || 0) : gross * (Number(line.discountPct || 0) / 100))
+      }, 0),
+    [lines],
+  )
+  const taxTotal = useMemo(
+    () =>
+      lines.reduce((sum, line) => {
+        const gross = Number(line.unitPrice ?? 0) * Number(line.qty || 0)
+        const mode = String(line.discountMode)
+        const discount = mode === "Amount" ? Number(line.discountAmount || 0) : gross * (Number(line.discountPct || 0) / 100)
+        const taxable = Math.max(0, gross - discount)
+        return sum + taxable * (Number(line.taxPct || 0) / 100)
+      }, 0),
+    [lines],
+  )
+  const netTotal = Math.max(0, grossTotal - discountTotal)
+  const payableTotal = netTotal + taxTotal
+
+  async function submit() {
+    if (!customerId || !warehouseId || !cashierUserId) return setSubmitError("Select customer, warehouse, and cashier.")
+    if (lines.some((line) => Number(line.itemId) === 0)) return setSubmitError("Select an item for every line.")
+    if (lines.some((line) => Number(line.warehouseId) === 0)) return setSubmitError("Select a warehouse for every line.")
+    if (lines.some((line) => Number(line.uomId) === 0)) return setSubmitError("Select a valid UOM for every line.")
+
+    const payload: CreateSalesSlipRequest = {
+      customerId,
+      warehouseId,
+      cashierUserId,
+      lines: lines.map((line) => ({
+        itemId: Number(line.itemId),
+        uomId: Number(line.uomId),
+        warehouseId: Number(line.warehouseId),
+        qty: Number(line.qty),
+        freeQty: Number(line.freeQty),
+        unitPrice: line.unitPrice === null ? null : Number(line.unitPrice),
+        allowManualPriceOverride: line.allowManualPriceOverride,
+        discountMode: line.discountMode,
+        discountPct: Number(line.discountPct),
+        discountAmount: Number(line.discountAmount),
+        discountValue: Number(line.discountValue),
+        taxPct: Number(line.taxPct),
+        isFreeIssue: line.isFreeIssue,
+        parentLineId: line.parentLineId || null,
+      })),
+    }
+
+    setSaving(true)
+    setSubmitError(null)
+    try {
+      const created = await salesApi.createSlip(payload)
+      toast.success("Slip created", created.data.slipNo)
+      router.push(`/dashboard/sales/slips/${created.data.salesSlipId}`)
+    } catch (err) {
+      setSubmitError(errorMessage(err))
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  if (loading) {
+    return <div className="rounded-2xl border border-border bg-card p-8 text-muted-foreground shadow-[var(--shadow-panel)]">Loading masters...</div>
+  }
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div className="flex items-center gap-3">
+          <Link href="/dashboard/sales/slips" className={cn(buttonVariants({ variant: "outline", size: "icon" }))}>
+            <ArrowLeft className="size-4" />
+          </Link>
+          <div>
+            <h1 className="text-2xl font-bold text-foreground">New sales slip</h1>
+            <p className="text-base text-muted-foreground">Create counter sales slips from the live backend.</p>
+          </div>
+        </div>
+        <div className="flex flex-wrap gap-2">
+          <Button type="button" variant="outline" size="sm" onClick={addLine}>
+            <Plus className="size-4" /> Add line
+          </Button>
+          <Button size="sm" onClick={submit} disabled={saving}>
+            <Save className="size-4" /> {saving ? "Saving..." : "Save slip"}
+          </Button>
+        </div>
+      </div>
+
+      {submitError ? <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{submitError}</div> : null}
+
+      <section className="rounded-2xl border border-border bg-card p-4 shadow-[var(--shadow-panel)]">
+        <h2 className="text-sm font-semibold">Slip header</h2>
+        <div className="mt-3 grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
+          <div className="space-y-1.5">
+            <Label className="text-xs">Customer</Label>
+            <Select value={customerId ? String(customerId) : ""} onValueChange={(v) => setCustomerId(v ? Number(v) : null)}>
+              <SelectTrigger className="h-9 text-sm">
+                <SelectValue placeholder="Select customer" />
+              </SelectTrigger>
+              <SelectContent>
+                {customers.map((c) => (
+                  <SelectItem key={c.customerId} value={String(c.customerId)}>
+                    {c.customerCode} - {c.displayName ?? c.name}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          <div className="space-y-1.5">
+            <Label className="text-xs">Warehouse</Label>
+            <Select value={warehouseId ? String(warehouseId) : ""} onValueChange={(v) => setWarehouseId(v ? Number(v) : null)}>
+              <SelectTrigger className="h-9 text-sm">
+                <SelectValue placeholder="Select warehouse" />
+              </SelectTrigger>
+              <SelectContent>
+                {warehouses.map((w) => (
+                  <SelectItem key={w.warehouseId} value={String(w.warehouseId)}>
+                    {w.code} - {w.name}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          <div className="space-y-1.5">
+            <Label className="text-xs">Cashier</Label>
+            <Select value={cashierUserId ? String(cashierUserId) : ""} onValueChange={(v) => setCashierUserId(v ? Number(v) : null)}>
+              <SelectTrigger className="h-9 text-sm">
+                <SelectValue placeholder="Select cashier" />
+              </SelectTrigger>
+              <SelectContent>
+                {users.map((u) => (
+                  <SelectItem key={u.userId} value={String(u.userId)}>
+                    {u.displayName}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          <div className="space-y-1.5">
+            <Label className="text-xs">Slip summary</Label>
+            <div className="flex h-9 items-center gap-2 rounded-md border border-border bg-secondary/40 px-3 text-xs text-muted-foreground">
+              <Badge variant="outline" className="border-emerald-200 bg-emerald-50 text-emerald-800">
+                Draft
+              </Badge>
+              <span>{lkr.format(payableTotal)}</span>
+            </div>
+          </div>
+        </div>
+      </section>
+
+      <section className="rounded-2xl border border-border bg-card shadow-[var(--shadow-panel)]">
+        <div className="flex items-center justify-between border-b border-border px-4 py-3">
+          <h2 className="text-sm font-semibold">Slip lines</h2>
+          <Button type="button" variant="outline" size="sm" onClick={addLine}>
+            <Plus className="size-4" /> Add line
+          </Button>
+        </div>
+        <div className="overflow-x-auto">
+          <Table className="text-sm">
+            <TableHeader>
+              <TableRow>
+                <TableHead className="h-12 px-4 text-sm">#</TableHead>
+                <TableHead className="h-12 px-4 text-sm">Item</TableHead>
+                <TableHead className="h-12 px-4 text-sm">UOM</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Qty</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Free</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Unit price</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Discount %</TableHead>
+                <TableHead className="h-12 px-4 text-sm text-right">Line total</TableHead>
+                <TableHead className="h-12 px-4 text-sm" />
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {lines.map((line, idx) => {
+                const lineGross = Number(line.unitPrice ?? 0) * Number(line.qty || 0)
+                const lineDiscount =
+                  String(line.discountMode) === "Amount"
+                    ? Number(line.discountAmount || 0)
+                    : lineGross * (Number(line.discountPct || 0) / 100)
+                const lineNet = Math.max(0, lineGross - lineDiscount)
+
+                return (
+                  <TableRow key={line.key} className="align-middle">
+                    <TableCell className="px-4 py-2 text-xs text-muted-foreground">{idx + 1}</TableCell>
+                    <TableCell className="px-4 py-2 min-w-64">
+                      <Select value={line.itemId ? String(line.itemId) : ""} onValueChange={(v) => selectItem(line.key, Number(v))}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="Select item" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {items.map((candidate) => (
+                            <SelectItem key={candidate.itemId} value={String(candidate.itemId)}>
+                              {candidate.sku} - {candidate.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2 min-w-36">
+                      <Select value={line.uomId ? String(line.uomId) : ""} onValueChange={(v) => updateLine(line.key, { uomId: Number(v) })}>
+                        <SelectTrigger className="h-9 text-sm">
+                          <SelectValue placeholder="UOM" />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {uoms.map((u) => (
+                            <SelectItem key={u.uomId} value={String(u.uomId)}>
+                              {u.name}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        step="0.01"
+                        value={line.qty}
+                        onChange={(e) => updateLine(line.key, { qty: Number(e.target.value) })}
+                        className="h-9 w-24 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        step="0.01"
+                        value={line.freeQty}
+                        onChange={(e) => updateLine(line.key, { freeQty: Number(e.target.value) })}
+                        className="h-9 w-24 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        step="0.01"
+                        value={line.unitPrice ?? ""}
+                        onChange={(e) => updateLine(line.key, { unitPrice: e.target.value === "" ? null : Number(e.target.value) })}
+                        className="h-9 w-28 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2">
+                      <Input
+                        type="number"
+                        min="0"
+                        max="100"
+                        step="0.5"
+                        value={line.discountPct}
+                        onChange={(e) => updateLine(line.key, { discountPct: Number(e.target.value) || 0 })}
+                        className="h-9 w-24 text-right font-mono text-sm tabular-nums"
+                      />
+                    </TableCell>
+                    <TableCell className="px-4 py-2 text-right font-mono font-semibold tabular-nums">{lkr.format(lineNet)}</TableCell>
+                    <TableCell className="px-4 py-2 text-right">
+                      <Button
+                        variant="ghost"
+                        size="icon"
+                        className="size-8 text-muted-foreground"
+                        onClick={() => removeLine(line.key)}
+                        disabled={lines.length === 1}
+                      >
+                        <Trash2 className="size-4" />
+                      </Button>
+                    </TableCell>
+                  </TableRow>
+                )
+              })}
+            </TableBody>
+          </Table>
+        </div>
+      </section>
+
+      <section className="grid gap-4 md:grid-cols-2">
+        <div className="rounded-2xl border border-border bg-card p-4 shadow-[var(--shadow-panel)]">
+          <h3 className="text-sm font-semibold">Slip notes</h3>
+          <ul className="mt-3 space-y-2 text-sm text-muted-foreground">
+            <li className="rounded-md border border-border px-3 py-2">Cashier posting follows the standard sales-slip workflow.</li>
+            <li className="rounded-md border border-border px-3 py-2">Free issue lines are captured from the slip itself, not from a separate register here.</li>
+            <li className="rounded-md border border-border px-3 py-2">Use the slip detail page after save to post or cancel.</li>
+          </ul>
+        </div>
+
+        <dl className="rounded-2xl border border-border bg-card p-4 text-sm shadow-[var(--shadow-panel)]">
+          {[
+            ["Gross", lkr.format(grossTotal)],
+            ["Discount", `-${lkr.format(discountTotal)}`],
+            ["Net", lkr.format(netTotal)],
+            ["Tax", lkr.format(taxTotal)],
+          ].map(([k, v]) => (
+            <div key={k} className="flex items-center justify-between py-1.5">
+              <dt className="text-muted-foreground">{k}</dt>
+              <dd className="font-mono tabular-nums">{v}</dd>
+            </div>
+          ))}
+          <div className="mt-2 flex items-center justify-between border-t border-border pt-3">
+            <dt className="font-semibold">Payable</dt>
+            <dd className="font-mono text-base font-semibold tabular-nums">{lkr.format(payableTotal)}</dd>
+          </div>
+        </dl>
+      </section>
+
+      <div className="flex justify-end gap-3">
+        <Link href="/dashboard/sales/slips" className={cn(buttonVariants({ variant: "outline", size: "lg" }))}>
+          Cancel
+        </Link>
+        <Button size="lg" onClick={submit} disabled={saving}>
+          {saving ? "Saving..." : "Create slip"}
+        </Button>
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/sales/slips/page.tsx

@@ -0,0 +1,229 @@
+"use client"
+
+import { useEffect, useMemo, useState } from "react"
+import Link from "next/link"
+import { ChevronLeft, ChevronRight, Eye, Filter, Package2, Plus, Printer } from "lucide-react"
+
+import { salesApi } from "@/lib/api/sales"
+import { errorMessage } from "@/lib/error-map"
+import { Button, buttonVariants } from "@/components/ui/button"
+import { Badge } from "@/components/ui/badge"
+import { Input } from "@/components/ui/input"
+import { Skeleton } from "@/components/ui/skeleton"
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table"
+import { cn } from "@/lib/utils"
+import { PaginationMeta } from "@/types/common"
+import { SalesSlipStatus, SalesSlipSummary } from "@/types/sales"
+
+type StatusFilter = SalesSlipStatus | "All"
+
+const PAGE_SIZE = 10
+const tabs = ["All", "Draft", "Posted", "Cancelled"] as const
+
+function statusClass(status: SalesSlipStatus) {
+  switch (status) {
+    case "Draft":
+      return "border-amber-200 bg-amber-50 text-amber-800"
+    case "Posted":
+      return "border-emerald-200 bg-emerald-50 text-emerald-800"
+    case "Cancelled":
+      return "border-rose-200 bg-rose-50 text-rose-800"
+  }
+}
+
+export default function SalesSlipsPage() {
+  const [rows, setRows] = useState<SalesSlipSummary[] | null>(null)
+  const [pagination, setPagination] = useState<PaginationMeta | null>(null)
+  const [error, setError] = useState<string | null>(null)
+  const [status, setStatus] = useState<StatusFilter>("All")
+  const [searchInput, setSearchInput] = useState("")
+  const [query, setQuery] = useState("")
+  const [page, setPage] = useState(1)
+
+  useEffect(() => {
+    const timeout = setTimeout(() => setQuery(searchInput.trim()), 300)
+    return () => clearTimeout(timeout)
+  }, [searchInput])
+
+  useEffect(() => setPage(1), [query, status])
+
+  useEffect(() => {
+    setError(null)
+    salesApi
+      .listSlips({ page, pageSize: PAGE_SIZE, status: status === "All" ? undefined : status })
+      .then((res) => {
+        setRows(res.items)
+        setPagination(res.pagination)
+      })
+      .catch((err) => setError(errorMessage(err)))
+  }, [page, status])
+
+  const visibleRows = useMemo(
+    () =>
+      rows?.filter((row) =>
+        `${row.slipNo} ${row.customerSnapshotName}`.toLowerCase().includes(query.toLowerCase())
+      ) ?? [],
+    [rows, query]
+  )
+  const hasFilters = status !== "All" || query.length > 0
+  const grossTotal = visibleRows.reduce((sum, row) => sum + row.totals.subtotal, 0)
+  const discountTotal = visibleRows.reduce((sum, row) => sum + row.totals.discountTotal, 0)
+  const netTotal = visibleRows.reduce((sum, row) => sum + row.totals.grandTotal, 0)
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div>
+          <h1 className="text-2xl font-bold text-foreground">Sales Slips</h1>
+          <p className="text-base text-muted-foreground">Counter sales register with posting and cancellation flow.</p>
+        </div>
+        <div className="flex flex-wrap gap-2">
+          <Button variant="outline" size="lg">
+            <Printer className="size-5" />
+            Print batch
+          </Button>
+          <Link href="/dashboard/sales/slips/new" className={cn(buttonVariants({ size: "lg" }))}>
+            <Plus className="size-5" />
+            New Slip
+          </Link>
+        </div>
+      </div>
+
+      <div className="rounded-2xl border bg-card shadow-sm">
+        <div className="flex flex-col gap-3 border-b px-4 py-4 lg:flex-row lg:items-center">
+          <div className="flex flex-wrap gap-2">
+            {tabs.map((t) => (
+              <button
+                key={t}
+                onClick={() => setStatus(t)}
+                className={cn(
+                  "rounded-full border px-3 py-1.5 text-xs font-medium transition-colors",
+                  status === t ? "border-primary bg-primary text-primary-foreground" : "border-border text-muted-foreground hover:text-foreground"
+                )}
+              >
+                {t}
+              </button>
+            ))}
+          </div>
+
+          <div className="flex flex-1 flex-col gap-3 lg:flex-row lg:items-center lg:justify-end">
+            <Input
+              value={searchInput}
+              onChange={(e) => setSearchInput(e.target.value)}
+              placeholder="Filter by customer or slip number"
+              className="h-12 w-full lg:max-w-sm"
+            />
+            <Button variant="outline" size="sm" className="lg:ml-auto">
+              <Filter className="size-4" />
+              Advanced
+            </Button>
+          </div>
+        </div>
+
+        {error && <div className="mx-4 mt-4 rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>}
+
+        {!error && rows === null && (
+          <div className="flex flex-col gap-3 px-4 py-4">
+            {Array.from({ length: 5 }).map((_, i) => (
+              <Skeleton key={i} className="h-14 w-full" />
+            ))}
+          </div>
+        )}
+
+        {!error && rows !== null && visibleRows.length === 0 && (
+          <div className="flex flex-col items-center gap-4 px-4 py-20 text-center">
+            <Package2 className="size-12 text-muted-foreground" />
+            <p className="text-base text-muted-foreground">{hasFilters ? "No slips match your filters." : "No slips yet."}</p>
+          </div>
+        )}
+
+        {!error && rows !== null && visibleRows.length > 0 && (
+          <>
+            <div className="overflow-x-auto">
+              <Table className="text-base">
+                <TableHeader>
+                  <TableRow>
+                    <TableHead className="h-12 px-4 text-sm">Slip</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Customer</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Date</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Status</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Lines</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Gross</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Discount</TableHead>
+                    <TableHead className="h-12 px-4 text-sm text-right">Net</TableHead>
+                    <TableHead className="h-12 px-4 text-sm">Actions</TableHead>
+                  </TableRow>
+                </TableHeader>
+                <TableBody>
+                  {visibleRows.map((row) => (
+                    <TableRow key={row.salesSlipId} className="hover:bg-muted/40">
+                      <TableCell className="px-4 py-3.5 font-medium">
+                        <Link href={`/dashboard/sales/slips/${row.salesSlipId}`} className="hover:underline">
+                          {row.slipNo}
+                        </Link>
+                      </TableCell>
+                      <TableCell className="px-4 py-3.5">{row.customerSnapshotName}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-muted-foreground">{new Date(row.createdAt).toLocaleDateString()}</TableCell>
+                      <TableCell className="px-4 py-3.5">
+                        <Badge variant="outline" className={statusClass(row.status)}>
+                          {row.status}
+                        </Badge>
+                      </TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums">{row.totals.freeQtyTotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums">{row.totals.subtotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono tabular-nums text-muted-foreground">-{row.totals.discountTotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5 text-right font-mono font-semibold tabular-nums">{row.totals.grandTotal.toFixed(2)}</TableCell>
+                      <TableCell className="px-4 py-3.5">
+                        <div className="flex justify-end">
+                          <Link href={`/dashboard/sales/slips/${row.salesSlipId}`} className="inline-flex h-8 w-8 items-center justify-center rounded-full border border-border text-muted-foreground hover:bg-muted hover:text-foreground" aria-label={`View slip ${row.slipNo}`}>
+                            <Eye className="size-4" />
+                          </Link>
+                        </div>
+                      </TableCell>
+                    </TableRow>
+                  ))}
+                </TableBody>
+              </Table>
+            </div>
+
+            <div className="border-t px-4 py-3">
+              <div className="grid gap-3 text-sm md:grid-cols-3">
+                <div className="rounded-lg border bg-muted/20 px-3 py-2">
+                  <div className="text-muted-foreground">Gross total</div>
+                  <div className="font-mono text-base font-semibold tabular-nums">{grossTotal.toFixed(2)}</div>
+                </div>
+                <div className="rounded-lg border bg-muted/20 px-3 py-2">
+                  <div className="text-muted-foreground">Discount total</div>
+                  <div className="font-mono text-base font-semibold tabular-nums">-{discountTotal.toFixed(2)}</div>
+                </div>
+                <div className="rounded-lg border bg-muted/20 px-3 py-2">
+                  <div className="text-muted-foreground">Net total</div>
+                  <div className="font-mono text-base font-semibold tabular-nums">{netTotal.toFixed(2)}</div>
+                </div>
+              </div>
+            </div>
+
+            {pagination && pagination.totalPages > 1 && (
+              <div className="flex flex-col gap-3 border-t px-4 py-4 sm:flex-row sm:items-center sm:justify-between">
+                <p className="text-sm text-muted-foreground">
+                  Showing {(pagination.page - 1) * pagination.pageSize + 1}-{Math.min(pagination.page * pagination.pageSize, pagination.totalItems)} of {pagination.totalItems}
+                </p>
+                <div className="flex items-center gap-2">
+                  <Button type="button" variant="outline" size="sm" disabled={pagination.page <= 1} onClick={() => setPage((p) => Math.max(1, p - 1))}>
+                    <ChevronLeft />
+                    Previous
+                  </Button>
+                  <span className="text-sm text-muted-foreground">Page {pagination.page} of {pagination.totalPages}</span>
+                  <Button type="button" variant="outline" size="sm" disabled={pagination.page >= pagination.totalPages} onClick={() => setPage((p) => Math.min(pagination.totalPages, p + 1))}>
+                    Next
+                    <ChevronRight />
+                  </Button>
+                </div>
+              </div>
+            )}
+          </>
+        )}
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/app/dashboard/settings/company-profile/page.tsx

@@ -0,0 +1,135 @@
+"use client"
+
+import { useEffect, useState } from "react"
+import Link from "next/link"
+import { ArrowLeft, Building2, Save } from "lucide-react"
+
+import { companyApi } from "@/lib/api/company"
+import { errorMessage } from "@/lib/error-map"
+import { cn } from "@/lib/utils"
+import { CompanyProfile } from "@/types/company"
+
+import { buttonVariants, Button } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Label } from "@/components/ui/label"
+import { Skeleton } from "@/components/ui/skeleton"
+import { toast } from "@/components/ui/toast"
+
+export default function CompanyProfilePage() {
+  const [profile, setProfile] = useState<CompanyProfile | null>(null)
+  const [etag, setEtag] = useState<string | null>(null)
+  const [error, setError] = useState<string | null>(null)
+  const [saving, setSaving] = useState(false)
+
+  useEffect(() => {
+    companyApi
+      .getProfile()
+      .then((res) => {
+        setProfile(res.data)
+        setEtag(res.etag)
+      })
+      .catch((err) => setError(errorMessage(err)))
+  }, [])
+
+  function patch<K extends keyof CompanyProfile>(key: K, value: CompanyProfile[K]) {
+    setProfile((prev) => (prev ? { ...prev, [key]: value } : prev))
+  }
+
+  async function save() {
+    if (!profile || !etag) return
+    setSaving(true)
+    setError(null)
+    try {
+      const updated = await companyApi.updateProfile(profile, etag)
+      setProfile(updated.data)
+      setEtag(updated.etag)
+      toast.success("Company profile saved", updated.data.legalName)
+    } catch (err) {
+      setError(errorMessage(err))
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  return (
+    <div className="flex flex-col gap-6">
+      <div className="flex items-center gap-3">
+        <Link href="/dashboard/settings" className={cn(buttonVariants({ variant: "ghost", size: "icon-lg" }))}>
+          <ArrowLeft className="size-5" />
+        </Link>
+        <div>
+          <h1 className="text-2xl font-bold text-foreground">Company Profile</h1>
+          <p className="text-base text-muted-foreground">Invoice header, tax details, logo, and bank information.</p>
+        </div>
+      </div>
+
+      {error && <div className="rounded-lg border border-destructive/30 bg-destructive/5 p-5 text-base text-destructive">{error}</div>}
+      {!error && !profile && <Skeleton className="h-64 w-full" />}
+
+      {!error && profile && (
+        <div className="flex flex-col gap-6 rounded-2xl border p-6">
+          <div className="flex items-center gap-2">
+            <Building2 className="size-5 text-primary" />
+            <h2 className="text-lg font-semibold">Invoice Header</h2>
+          </div>
+
+          <div className="grid gap-4 md:grid-cols-2">
+            <Field label="Legal Name" value={profile.legalName} onChange={(v) => patch("legalName", v)} />
+            <Field label="Trade Name" value={profile.tradeName ?? ""} onChange={(v) => patch("tradeName", v)} />
+            <Field label="Logo URL" value={profile.logoUrl ?? ""} onChange={(v) => patch("logoUrl", v)} />
+            <Field label="Tax Registration No" value={profile.taxRegistrationNo ?? ""} onChange={(v) => patch("taxRegistrationNo", v)} />
+            <Field label="VAT Registration No" value={profile.vatRegistrationNo ?? ""} onChange={(v) => patch("vatRegistrationNo", v)} />
+            <Field label="Phone" value={profile.phone ?? ""} onChange={(v) => patch("phone", v)} />
+            <Field label="Email" value={profile.email ?? ""} onChange={(v) => patch("email", v)} />
+            <Field label="City" value={profile.city ?? ""} onChange={(v) => patch("city", v)} />
+            <Field label="Country" value={profile.country ?? ""} onChange={(v) => patch("country", v)} />
+            <Field label="Address Line 1" value={profile.addressLine1 ?? ""} onChange={(v) => patch("addressLine1", v)} />
+            <Field label="Address Line 2" value={profile.addressLine2 ?? ""} onChange={(v) => patch("addressLine2", v)} />
+          </div>
+
+          <div className="border-t" />
+
+          <div className="flex items-center gap-2">
+            <Save className="size-5 text-primary" />
+            <h2 className="text-lg font-semibold">Bank Details</h2>
+          </div>
+
+          <div className="grid gap-4 md:grid-cols-2">
+            <Field label="Bank Name" value={profile.bankName ?? ""} onChange={(v) => patch("bankName", v)} />
+            <Field label="Bank Branch" value={profile.bankBranch ?? ""} onChange={(v) => patch("bankBranch", v)} />
+            <Field label="Account Name" value={profile.accountName ?? ""} onChange={(v) => patch("accountName", v)} />
+            <Field label="Account Number" value={profile.accountNumber ?? ""} onChange={(v) => patch("accountNumber", v)} />
+            <Field label="SWIFT Code" value={profile.swiftCode ?? ""} onChange={(v) => patch("swiftCode", v)} />
+            <Field label="Footer Note" value={profile.footerNote ?? ""} onChange={(v) => patch("footerNote", v)} />
+          </div>
+
+          <div className="flex justify-end gap-3">
+            <Link href="/dashboard/settings" className={cn(buttonVariants({ variant: "outline", size: "lg" }))}>
+              Cancel
+            </Link>
+            <Button size="lg" onClick={save} disabled={saving}>
+              {saving ? "Saving..." : "Save Profile"}
+            </Button>
+          </div>
+        </div>
+      )}
+    </div>
+  )
+}
+
+function Field({
+  label,
+  value,
+  onChange,
+}: {
+  label: string
+  value: string
+  onChange: (value: string) => void
+}) {
+  return (
+    <div className="flex flex-col gap-2">
+      <Label>{label}</Label>
+      <Input value={value} onChange={(e) => onChange(e.target.value)} />
+    </div>
+  )
+}

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

@@ -1,5 +1,5 @@
 import Link from "next/link"
-import { ShieldCheck, SlidersHorizontal, Users } from "lucide-react"
+import { Building2, ShieldCheck, SlidersHorizontal, Users } from "lucide-react"
 
 const cards = [
   {
@@ -20,6 +20,12 @@ const cards = [
     icon: SlidersHorizontal,
     description: "Configure product and master-data options",
   },
+  {
+    title: "Company Profile",
+    href: "/dashboard/settings/company-profile",
+    icon: Building2,
+    description: "Invoice header, tax, and bank details",
+  },
 ]
 
 export default function SettingsPage() {

Frontend/erp-system/app/globals.css

@@ -219,3 +219,34 @@
   }
 }
 
+@media print {
+  body {
+    background: white !important;
+    color: black !important;
+  }
+
+  .print\:hidden {
+    display: none !important;
+  }
+
+  .invoice-sheet {
+    border: 0 !important;
+    box-shadow: none !important;
+    padding: 0 !important;
+  }
+
+  .invoice-header {
+    break-inside: avoid;
+  }
+
+  .invoice-sheet table {
+    width: 100% !important;
+  }
+
+  .invoice-sheet tr,
+  .invoice-sheet td,
+  .invoice-sheet th {
+    break-inside: avoid;
+  }
+}
+

Frontend/erp-system/app/layout.tsx

@@ -1,7 +1,6 @@
 import type { Metadata } from "next";
 import { Geist, Geist_Mono } from "next/font/google";
-import { ThemeProvider } from "next-themes";
-import { TooltipProvider } from "@/components/ui/tooltip";
+import { Providers } from "@/components/providers";
 import "./globals.css";
 
 const geistSans = Geist({
@@ -31,14 +30,7 @@ export default function RootLayout({
       suppressHydrationWarning
     >
       <body className="min-h-full flex flex-col">
-        <ThemeProvider
-          attribute="class"
-          defaultTheme="light"
-          themes={["light", "dark", "vibrant"]}
-          disableTransitionOnChange
-        >
-          <TooltipProvider>{children}</TooltipProvider>
-        </ThemeProvider>
+        <Providers>{children}</Providers>
       </body>
     </html>
   );

Frontend/erp-system/app/login/page.tsx

@@ -31,6 +31,8 @@ function LoginForm() {
   const [showPassword, setShowPassword] = useState(false)
   const [remember, setRemember] = useState(false)
   const [submitError, setSubmitError] = useState<string | null>(null)
+  const returnTo = searchParams.get("next")
+  const sessionNotice = returnTo ? "Your session is missing or expired. Sign in again to continue." : null
 
   const form = useForm<LoginValues>({
     resolver: zodResolver(loginSchema),
@@ -85,6 +87,11 @@ function LoginForm() {
         <div className="text-center">
           <h1 className="text-3xl font-bold text-foreground">Sign in to your account</h1>
           <p className="mt-3 text-base text-muted-foreground">Access your ERP dashboard and manage your business</p>
+          {sessionNotice ? (
+            <div className="mt-4 rounded-lg border border-amber-300 bg-amber-50 px-4 py-3 text-sm text-amber-900">
+              {sessionNotice}
+            </div>
+          ) : null}
         </div>
 
         <form onSubmit={onSubmit} noValidate className="mt-10 space-y-6" aria-describedby="form-errors" aria-live="polite">

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

@@ -33,6 +33,7 @@ import {
   PlayCircle,
   PieChart,
   Receipt,
+  ReceiptText,
   Ruler,
   Scale,
   Settings,
@@ -99,6 +100,20 @@ const navItems: {
       { title: "RFQs", code: "procurement.rfqs", href: "/dashboard/procurement/rfqs", icon: FileText },
     ],
   },
+  {
+    title: "Sales",
+    code: "sales",
+    href: "/dashboard/sales",
+    landingHref: "/dashboard/sales/invoices",
+    icon: ReceiptText,
+    chevron: true,
+    children: [
+      { title: "Invoices", code: "sales.invoices", href: "/dashboard/sales/invoices", icon: FileText },
+      { title: "Slips", code: "sales.slips", href: "/dashboard/sales/slips", icon: ShoppingCart },
+      { title: "Free Issues", code: "sales.free-issues", href: "/dashboard/sales/free-issues", icon: PackageX },
+      { title: "Reports", code: "sales.reports", href: "/dashboard/sales/reports", icon: FileBarChart },
+    ],
+  },
   { 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 },
@@ -386,14 +401,14 @@ export function AppSidebar() {
   // flashing the full menu to a restricted role. Once resolved, a nav item
   // is visible if its own code is granted, or (for parents) if any child is.
   //
-  // "procurement", "hrm" and "production" are exempted from that check (frontend-only): no
+  // "procurement", "hrm", "sales" and "production" are exempted from that check (frontend-only): no
   // role is currently seeded with NAV:procurement/NAV:hrm/NAV:production or their children
   // server-side, which would hide the whole section for everyone. Remove each bypass once roles are granted
   // the permission properly (Settings → Roles → Sidebar permissions) or a backend seed
   // grants it. This is also flagged in 02-SECURITY.md as the AR-09 sidebar-visibility
   // stopgap for HRM's salary/PII data — it hides HRM from the UI but doesn't enforce
   // anything server-side.
-  const bypassCodes = new Set(["procurement", "hrm", "production"])
+  const bypassCodes = new Set(["procurement", "sales", "hrm", "production"])
   const visibleItems = loading
     ? []
     : navItems

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

@@ -111,6 +111,7 @@ function titleFromPath(pathname: string) {
   if (pathname === "/dashboard/products/brands") return "Brands"
   if (pathname === "/dashboard/products/item-types") return "Item Types"
   if (pathname === "/dashboard/products/settings") return "Product Configuration"
+  if (pathname === "/dashboard/settings/company-profile") return "Company Profile"
   if (/^\/dashboard\/products\/[^/]+$/.test(pathname)) return "Item"
 
   const segment = pathname.split("/").filter(Boolean).pop() ?? "dashboard"

Frontend/erp-system/components/dashboard/recent-orders-table.tsx

@@ -29,9 +29,9 @@ const statusStyles: Record<Order["status"], string> = {
 }
 
 // Use a fixed locale to avoid hydration mismatches between server and client
-const currency = new Intl.NumberFormat("en-US", {
+const currency = new Intl.NumberFormat("en-LK", {
   style: "currency",
-  currency: "USD",
+  currency: "LKR",
 })
 
 const columns: DataTableColumn<Order>[] = [

Frontend/erp-system/components/providers.tsx

@@ -0,0 +1,13 @@
+"use client"
+
+import { ThemeProvider } from "next-themes"
+
+import { TooltipProvider } from "@/components/ui/tooltip"
+
+export function Providers({ children }: { children: React.ReactNode }) {
+  return (
+    <ThemeProvider attribute="class" defaultTheme="light" themes={["light", "dark", "vibrant"]} disableTransitionOnChange>
+      <TooltipProvider>{children}</TooltipProvider>
+    </ThemeProvider>
+  )
+}

Frontend/erp-system/components/sales/FreeIssuePromotionSuggestions.tsx

@@ -0,0 +1,65 @@
+"use client"
+
+import Link from "next/link"
+import { Lightbulb, PackageCheck } from "lucide-react"
+
+import { buttonVariants } from "@/components/ui/button"
+import { cn } from "@/lib/utils"
+import { SalesFreeIssueSuggestion } from "@/types/sales"
+
+export function FreeIssuePromotionSuggestions({ suggestion }: { suggestion: SalesFreeIssueSuggestion | null }) {
+  if (!suggestion || suggestion.lines.length === 0) {
+    return (
+      <div className="rounded-2xl border border-dashed p-6 text-sm text-muted-foreground">
+        No free-issue promotion suggestions were generated for this slip yet.
+      </div>
+    )
+  }
+
+  return (
+    <div className="rounded-2xl border p-4">
+      <div className="mb-4 flex items-center justify-between gap-3">
+        <div>
+          <div className="inline-flex items-center gap-2 rounded-full bg-amber-500/10 px-3 py-1 text-xs font-semibold uppercase tracking-wide text-amber-700">
+            <Lightbulb className="size-3.5" />
+            Backend suggestion
+          </div>
+          <h2 className="mt-2 text-lg font-semibold text-foreground">Free-issue promotions</h2>
+          <p className="text-sm text-muted-foreground">The server suggests reward quantities and alternate products for this slip.</p>
+        </div>
+        <Link href="/dashboard/sales/free-issues/new" className={cn(buttonVariants({ variant: "outline", size: "sm" }))}>
+          Create free issue
+        </Link>
+      </div>
+
+      <div className="grid gap-4 lg:grid-cols-2">
+        {suggestion.lines.map((line) => (
+          <div key={line.salesSlipLineId} className="rounded-xl border bg-muted/20 p-4">
+            <div className="flex items-start justify-between gap-3">
+              <div>
+                <div className="font-medium text-foreground">{line.itemName}</div>
+                <div className="text-sm text-muted-foreground">{line.itemSku} • Qty {line.qty}</div>
+              </div>
+              <div className="rounded-full bg-primary/10 px-3 py-1 text-xs font-semibold text-primary">
+                Buy {line.triggerQty} get {line.suggestedFreeQty} free
+              </div>
+            </div>
+
+            <div className="mt-3 flex flex-wrap gap-2 text-sm">
+              {line.rewardOptions.map((option, index) => (
+                <span key={option.itemId} className={cn("inline-flex items-center gap-1 rounded-full border px-3 py-1", index === 0 && "border-primary bg-primary/5 text-primary") }>
+                  {index === 0 ? <PackageCheck className="size-3.5" /> : null}
+                  {option.name}
+                </span>
+              ))}
+            </div>
+
+            <div className="mt-3 text-sm text-muted-foreground">
+              Suggested free qty: <span className="font-medium text-foreground">{line.suggestedFreeQty.toFixed(2)}</span>
+            </div>
+          </div>
+        ))}
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/components/sales/FreeIssueSuggestions.tsx

@@ -0,0 +1,42 @@
+"use client"
+
+import Link from "next/link"
+
+import { buttonVariants } from "@/components/ui/button"
+import { cn } from "@/lib/utils"
+import { SalesSlipSummary } from "@/types/sales"
+
+export function FreeIssueSuggestions({ rows }: { rows: SalesSlipSummary[] }) {
+  if (rows.length === 0) return null
+
+  return (
+    <div className="rounded-2xl border p-4">
+      <div className="mb-3 flex items-center justify-between gap-3">
+        <div>
+          <h2 className="text-lg font-semibold text-foreground">Free issue suggestions</h2>
+          <p className="text-sm text-muted-foreground">Recent free-issue slips created from the free-issues page.</p>
+        </div>
+        <Link href="/dashboard/sales/free-issues" className={cn(buttonVariants({ variant: "outline", size: "sm" }))}>
+          Open free issues
+        </Link>
+      </div>
+
+      <div className="grid gap-3 md:grid-cols-2 xl:grid-cols-3">
+        {rows.map((row) => (
+          <Link
+            key={row.salesSlipId}
+            href={`/dashboard/sales/free-issues/${row.salesSlipId}`}
+            className="rounded-xl border bg-muted/20 p-3 transition-colors hover:bg-muted/40"
+          >
+            <div className="flex items-center justify-between gap-2">
+              <div className="font-medium text-foreground">{row.slipNo}</div>
+              <div className="text-xs uppercase tracking-wide text-muted-foreground">{row.status}</div>
+            </div>
+            <div className="mt-1 text-sm text-muted-foreground">{row.customerSnapshotName}</div>
+            <div className="mt-2 text-sm text-foreground">Free qty total: {row.totals.freeQtyTotal.toFixed(2)}</div>
+          </Link>
+        ))}
+      </div>
+    </div>
+  )
+}

Frontend/erp-system/lib/api/customers.ts

@@ -0,0 +1,15 @@
+import { apiRequest, buildQuery } from "@/lib/api-client"
+import { PagedResponse } from "@/types/common"
+import { Customer } from "@/types/customers"
+
+export interface ListCustomersParams {
+  page?: number
+  pageSize?: number
+  q?: string
+}
+
+export const customersApi = {
+  list(params: ListCustomersParams = {}): Promise<PagedResponse<Customer>> {
+    return apiRequest<PagedResponse<Customer>>(`/customers${buildQuery(params)}`)
+  },
+}

Frontend/erp-system/lib/api/sales.ts

@@ -0,0 +1,139 @@
+import { apiRequest, apiRequestWithETag, buildQuery } from "@/lib/api-client"
+import { ApiResult, PagedResponse } from "@/types/common"
+import {
+  CreateSalesInvoiceRequest,
+  CreateSalesSlipRequest,
+  SalesInvoice,
+  SalesInvoiceStatus,
+  SalesInvoicePostingCheck,
+  SalesInvoiceSummary,
+  SalesListFilterParams,
+  SalesReportDefinition,
+  SalesReportQueryRequest,
+  SalesReportQueryResponse,
+  SalesFreeIssueSuggestion,
+  FreeIssueDetail,
+  FreeIssueSummary,
+  SalesSlip,
+  SalesSlipStatus,
+  SalesSlipPostingCheck,
+  SalesSlipSummary,
+  UpdateSalesInvoiceRequest,
+  UpdateSalesSlipRequest,
+} from "@/types/sales"
+
+type SalesReportId = string
+
+export interface ListSalesInvoicesParams extends SalesListFilterParams {
+  status?: SalesInvoiceStatus
+}
+
+export interface ListSalesSlipsParams extends SalesListFilterParams {
+  status?: SalesSlipStatus
+}
+
+export interface ListFreeIssuesParams extends SalesListFilterParams {
+  status?: SalesSlipStatus
+}
+
+export const salesApi = {
+  listInvoices(params: ListSalesInvoicesParams = {}): Promise<PagedResponse<SalesInvoiceSummary>> {
+    return apiRequest<PagedResponse<SalesInvoiceSummary>>(`/sales-invoices${buildQuery(params)}`)
+  },
+
+  getInvoice(salesInvoiceId: number): Promise<ApiResult<SalesInvoice>> {
+    return apiRequestWithETag<SalesInvoice>(`/sales-invoices/${salesInvoiceId}`)
+  },
+
+  createInvoice(request: CreateSalesInvoiceRequest): Promise<ApiResult<SalesInvoice>> {
+    return apiRequestWithETag<SalesInvoice>("/sales-invoices", { method: "POST", body: request })
+  },
+
+  updateInvoice(salesInvoiceId: number, request: UpdateSalesInvoiceRequest, ifMatch: string): Promise<ApiResult<SalesInvoice>> {
+    return apiRequestWithETag<SalesInvoice>(`/sales-invoices/${salesInvoiceId}`, { method: "PUT", body: request, ifMatch })
+  },
+
+  postInvoice(salesInvoiceId: number): Promise<SalesInvoice> {
+    return apiRequest<SalesInvoice>(`/sales-invoices/${salesInvoiceId}/post`, { method: "POST" })
+  },
+
+  checkInvoicePosting(salesInvoiceId: number): Promise<SalesInvoicePostingCheck> {
+    return apiRequest<SalesInvoicePostingCheck>(`/sales-invoices/${salesInvoiceId}/posting-check`)
+  },
+
+  cancelInvoice(salesInvoiceId: number): Promise<SalesInvoice> {
+    return apiRequest<SalesInvoice>(`/sales-invoices/${salesInvoiceId}/cancel`, { method: "POST" })
+  },
+
+  listSlips(params: ListSalesSlipsParams = {}): Promise<PagedResponse<SalesSlipSummary>> {
+    return apiRequest<PagedResponse<SalesSlipSummary>>(`/sales-slips${buildQuery(params)}`)
+  },
+
+  getSlip(salesSlipId: number): Promise<ApiResult<SalesSlip>> {
+    return apiRequestWithETag<SalesSlip>(`/sales-slips/${salesSlipId}`)
+  },
+
+  createSlip(request: CreateSalesSlipRequest): Promise<ApiResult<SalesSlip>> {
+    return apiRequestWithETag<SalesSlip>("/sales-slips", { method: "POST", body: request })
+  },
+
+  updateSlip(salesSlipId: number, request: UpdateSalesSlipRequest, ifMatch: string): Promise<ApiResult<SalesSlip>> {
+    return apiRequestWithETag<SalesSlip>(`/sales-slips/${salesSlipId}`, { method: "PUT", body: request, ifMatch })
+  },
+
+  postSlip(salesSlipId: number): Promise<SalesSlip> {
+    return apiRequest<SalesSlip>(`/sales-slips/${salesSlipId}/post`, { method: "POST" })
+  },
+
+  checkSlipPosting(salesSlipId: number): Promise<SalesSlipPostingCheck> {
+    return apiRequest<SalesSlipPostingCheck>(`/sales-slips/${salesSlipId}/posting-check`)
+  },
+
+  cancelSlip(salesSlipId: number): Promise<SalesSlip> {
+    return apiRequest<SalesSlip>(`/sales-slips/${salesSlipId}/cancel`, { method: "POST" })
+  },
+
+  listFreeIssues(params: ListFreeIssuesParams = {}): Promise<PagedResponse<FreeIssueSummary>> {
+    return apiRequest<PagedResponse<FreeIssueSummary>>(`/free-issues${buildQuery(params)}`)
+  },
+
+  getFreeIssue(freeIssueId: number): Promise<ApiResult<FreeIssueDetail>> {
+    return apiRequestWithETag<FreeIssueDetail>(`/free-issues/${freeIssueId}`)
+  },
+
+  createFreeIssue(request: CreateSalesSlipRequest): Promise<ApiResult<FreeIssueDetail>> {
+    return apiRequestWithETag<FreeIssueDetail>("/free-issues", { method: "POST", body: request })
+  },
+
+  updateFreeIssue(freeIssueId: number, request: UpdateSalesSlipRequest, ifMatch: string): Promise<ApiResult<FreeIssueDetail>> {
+    return apiRequestWithETag<FreeIssueDetail>(`/free-issues/${freeIssueId}`, { method: "PUT", body: request, ifMatch })
+  },
+
+  postFreeIssue(freeIssueId: number): Promise<FreeIssueDetail> {
+    return apiRequest<FreeIssueDetail>(`/free-issues/${freeIssueId}/post`, { method: "POST" })
+  },
+
+  checkFreeIssuePosting(freeIssueId: number): Promise<SalesSlipPostingCheck> {
+    return apiRequest<SalesSlipPostingCheck>(`/free-issues/${freeIssueId}/posting-check`)
+  },
+
+  cancelFreeIssue(freeIssueId: number): Promise<FreeIssueDetail> {
+    return apiRequest<FreeIssueDetail>(`/free-issues/${freeIssueId}/cancel`, { method: "POST" })
+  },
+
+  getFreeIssueSuggestions(salesSlipId: number): Promise<SalesFreeIssueSuggestion> {
+    return apiRequest<SalesFreeIssueSuggestion>(`/sales-slips/${salesSlipId}/free-issue-suggestions`)
+  },
+
+  listReports(): Promise<SalesReportDefinition[]> {
+    return apiRequest<SalesReportDefinition[]>("/reports/sales")
+  },
+
+  getReport(reportId: SalesReportId): Promise<SalesReportDefinition> {
+    return apiRequest<SalesReportDefinition>(`/reports/sales/${reportId}`)
+  },
+
+  queryReport(request: SalesReportQueryRequest): Promise<SalesReportQueryResponse> {
+    return apiRequest<SalesReportQueryResponse>("/reports/sales/query", { method: "POST", body: request })
+  },
+}

Frontend/erp-system/lib/sales-line-utils.ts

@@ -0,0 +1,6 @@
+import { ItemListItem } from "@/types/master-data"
+
+export function getSuggestedUnitPrice(items: ItemListItem[], itemId: number | null | undefined): number | null {
+  if (!itemId) return null
+  return items.find((item) => item.itemId === itemId)?.salePrice ?? null
+}

Frontend/erp-system/types/customers.ts

@@ -0,0 +1,24 @@
+import { EntityStatus } from "@/types/common"
+
+export type CustomerType = "B2B" | "B2C"
+
+export interface Customer {
+  customerId: number
+  customerCode: string
+  customerType: CustomerType
+  name: string
+  displayName: string | null
+  phone: string | null
+  email: string | null
+  addressLine1: string | null
+  addressLine2: string | null
+  city: string | null
+  country: string | null
+  taxRegistrationNo: string | null
+  creditLimit: number
+  creditDays: number
+  defaultWarehouseId: number | null
+  status: EntityStatus
+  createdAt: string
+  updatedAt: string | null
+}

Frontend/erp-system/types/sales.ts

@@ -0,0 +1,314 @@
+import { EntityStatus } from "@/types/common"
+
+export type SalesInvoiceType = "B2B" | "B2C" | "Cash" | "Credit"
+export type SalesInvoiceStatus = "Draft" | "Posted" | "Cancelled"
+export type SalesSlipStatus = "Draft" | "Posted" | "Cancelled"
+export type SalesDiscountMode = "Percentage" | "Amount"
+
+export interface SalesInvoiceLine {
+  salesInvoiceLineId: number
+  itemId: number
+  description: string
+  qty: number
+  freeQty: number
+  uomId: number
+  warehouseId: number
+  unitPrice: number
+  baseCost: number
+  priceSource: string
+  discountPct: number
+  discountAmount: number
+  discountMode: SalesDiscountMode
+  netUnitPrice: number
+  lineTotal: number
+  taxPct: number
+  taxAmount: number
+  isFreeIssue: boolean
+  parentLineId: number | null
+}
+
+export interface SalesInvoiceTotals {
+  subtotal: number
+  discountTotal: number
+  freeQtyTotal: number
+  taxTotal: number
+  grandTotal: number
+  roundOff: number
+  netPayable: number
+  paidAmount: number
+  balanceAmount: number
+}
+
+export interface SalesInvoiceSummary {
+  salesInvoiceId: number
+  invoiceNo: string
+  invoiceDate: string
+  customerId: number
+  customerSnapshotName: string
+  warehouseId: number
+  invoiceType: SalesInvoiceType
+  status: SalesInvoiceStatus
+  totals: SalesInvoiceTotals
+  createdAt: string
+}
+
+export interface SalesInvoicePostingIssue {
+  salesInvoiceLineId: number
+  itemId: number
+  itemSku: string
+  itemName: string
+  warehouseId: number
+  requestedQty: number
+  availableQty: number
+  shortQty: number
+  isFreeIssue: boolean
+}
+
+export interface SalesInvoicePostingCheck {
+  salesInvoiceId: number
+  invoiceNo: string
+  status: SalesInvoiceStatus
+  canPost: boolean
+  issues: SalesInvoicePostingIssue[]
+}
+
+export interface SalesSlipPostingIssue {
+  salesSlipLineId: number
+  itemId: number
+  itemSku: string
+  itemName: string
+  warehouseId: number
+  requestedQty: number
+  availableQty: number
+  shortQty: number
+  isFreeIssue: boolean
+}
+
+export interface SalesSlipPostingCheck {
+  salesSlipId: number
+  slipNo: string
+  status: SalesSlipStatus
+  canPost: boolean
+  issues: SalesSlipPostingIssue[]
+}
+
+export interface SalesInvoice extends SalesInvoiceSummary {
+  customerSnapshotTaxNo: string | null
+  createdBy: number
+  updatedAt: string | null
+  lines: SalesInvoiceLine[]
+}
+
+export interface CreateSalesInvoiceLineRequest {
+  itemId: number
+  uomId: number
+  warehouseId: number
+  qty: number
+  freeQty: number
+  unitPrice?: number | null
+  allowManualPriceOverride: boolean
+  discountMode: SalesDiscountMode
+  discountPct: number
+  discountAmount: number
+  discountValue: number
+  taxPct: number
+  isFreeIssue: boolean
+  parentLineId?: number | null
+}
+
+export interface CreateSalesInvoiceRequest {
+  customerId: number
+  warehouseId: number
+  invoiceType: SalesInvoiceType
+  lines: CreateSalesInvoiceLineRequest[]
+}
+
+export type UpdateSalesInvoiceRequest = CreateSalesInvoiceRequest
+
+export interface SalesSlipLine {
+  salesSlipLineId: number
+  itemId: number
+  description: string
+  qty: number
+  freeQty: number
+  uomId: number
+  warehouseId: number
+  unitPrice: number
+  baseCost: number
+  priceSource: string
+  discountPct: number
+  discountAmount: number
+  discountMode: SalesDiscountMode
+  netUnitPrice: number
+  lineTotal: number
+  taxPct: number
+  taxAmount: number
+  isFreeIssue: boolean
+  parentLineId: number | null
+}
+
+export interface SalesSlipTotals {
+  subtotal: number
+  discountTotal: number
+  freeQtyTotal: number
+  taxTotal: number
+  grandTotal: number
+  paidAmount: number
+  balanceAmount: number
+}
+
+export interface SalesSlipSummary {
+  salesSlipId: number
+  slipNo: string
+  slipDate: string
+  customerId: number
+  customerSnapshotName: string
+  warehouseId: number
+  status: SalesSlipStatus
+  totals: SalesSlipTotals
+  createdAt: string
+}
+
+export interface SalesSlip {
+  salesSlipId: number
+  slipNo: string
+  slipDate: string
+  customerId: number
+  customerSnapshotName: string
+  warehouseId: number
+  cashierUserId: number
+  status: SalesSlipStatus
+  createdAt: string
+  updatedAt: string | null
+  totals: SalesSlipTotals
+  lines: SalesSlipLine[]
+}
+
+export interface CreateSalesSlipLineRequest {
+  itemId: number
+  uomId: number
+  warehouseId: number
+  qty: number
+  freeQty: number
+  unitPrice?: number | null
+  allowManualPriceOverride: boolean
+  discountMode: SalesDiscountMode
+  discountPct: number
+  discountAmount: number
+  discountValue: number
+  taxPct: number
+  isFreeIssue: boolean
+  parentLineId?: number | null
+}
+
+export interface CreateSalesSlipRequest {
+  customerId: number
+  warehouseId: number
+  cashierUserId: number
+  lines: CreateSalesSlipLineRequest[]
+}
+
+export type UpdateSalesSlipRequest = CreateSalesSlipRequest
+
+export interface SalesReportDefinition {
+  id: string
+  name: string
+  description: string
+  supportedFilters: string[]
+}
+
+export interface SalesReportQueryRequest {
+  reportType: string
+  from: string
+  to: string
+  itemId?: number | null
+  customerId?: number | null
+  warehouseId?: number | null
+}
+
+export interface SalesReportQueryResponse {
+  reportType: string
+  from: string
+  to: string
+  rows: unknown[]
+}
+
+export interface SalesListFilterParams {
+  page?: number
+  pageSize?: number
+  status?: SalesInvoiceStatus | SalesSlipStatus
+  customerId?: number
+  warehouseId?: number
+}
+
+export interface FreeIssueSummaryItem extends SalesSlipSummary {
+  // Alias for the free issue route. Kept as a slip-shaped payload because the backend
+  // stores free issues as sales slips with free-issue line flags.
+  isFreeIssue?: boolean
+}
+
+export interface FreeIssueSummary {
+  salesSlipId: number
+  slipNo: string
+  status: SalesSlipStatus
+  createdAt: string
+  warehouseId: number
+  warehouseName: string
+  itemId: number
+  itemSku: string
+  itemName: string
+  uomId: number
+  uomName: string
+  qty: number
+  freeQty: number
+  schemeLabel: string
+}
+
+export interface FreeIssueDetail {
+  salesSlipId: number
+  slipNo: string
+  slipDate: string
+  status: SalesSlipStatus
+  customerId: number
+  customerSnapshotName: string
+  warehouseId: number
+  warehouseName: string
+  cashierUserId: number
+  createdAt: string
+  updatedAt: string | null
+  summary: FreeIssueSummary
+  lines: SalesSlipLine[]
+}
+
+export interface SalesFreeIssueRewardOption {
+  itemId: number
+  sku: string
+  name: string
+  salePrice: number | null
+}
+
+export interface SalesFreeIssueSuggestionLine {
+  salesSlipLineId: number
+  itemId: number
+  itemSku: string
+  itemName: string
+  qty: number
+  suggestedFreeQty: number
+  triggerQty: number
+  rewardOptions: SalesFreeIssueRewardOption[]
+}
+
+export interface SalesFreeIssueSuggestion {
+  salesSlipId: number
+  slipNo: string
+  slipDate: string
+  lines: SalesFreeIssueSuggestionLine[]
+}
+
+export interface SalesCustomer {
+  customerId: number
+  code: string
+  name: string
+  taxNo: string | null
+  status: EntityStatus
+}

docs/00-CORE.md

@@ -21,6 +21,7 @@ A modular ERP built in phases. **Phase 1** delivers the **Inventory & Supply Cha
 Full requirements live in the backend spec (see §7). This file does **not** duplicate them.
 
 **Phase 2 (HRM)** is now underway alongside Phase 1 — see §7 routing to `12-BACKEND-HRM.md` / `13-BACKEND-HRM-API.md` / `21-FRONTEND-HRM.md`.
+Sales has its own API reference at `14-BACKEND-SALES-API.md`.
 
 ---
 
@@ -45,6 +46,7 @@ erp-monorepo/
     ├── 02-SECURITY.md            # accepted-risks register + per-feature security checklist
     ├── 10-BACKEND-PHASE1.md      # backend spec: SRS + ER/entities + tech + architecture
     ├── 11-BACKEND-PHASE1.md      # backend API reference (complete req/res)
+    ├── 14-BACKEND-SALES-API.md   # sales API reference (invoices, slips, free issues, reports)
     ├── 12-GENERAL-LEDGER-INTEGRATION.md  # ERPCore ↔ external General Ledger service (transport only)
     ├── 20-FRONTEND.md            # frontend user-flows + architecture rules + validation posture
     └── 21-GENERAL-LEDGER-FRONTEND.md  # Ledgers section: reports UI + cash/bank accounts
@@ -344,6 +346,7 @@ All frontend work is governed by `20-FRONTEND.md`.
 | HRM API endpoints, request/response shapes, error catalog (Phase 2) | **`13-BACKEND-HRM-API.md`** |
 | Connecting to the external General Ledger service (proxy, config, API key) | **`12-GENERAL-LEDGER-INTEGRATION.md`** |
 | The Ledgers frontend section (reports, cash/bank accounts) | **`21-GENERAL-LEDGER-FRONTEND.md`** |
+| Sales API endpoints, request/response shapes, error catalog, enums | **`14-BACKEND-SALES-API.md`** |
 | Frontend user-flows, screen flow, architecture rules, validation posture (Phase 1) | **`20-FRONTEND.md`** |
 | HRM frontend user-flows (Phase 2) | **`21-FRONTEND-HRM.md`** |
 | Manufacturing requirements, business rules, entities, stock/costing integration, API (Phase 2) | **`30-BACKEND-PHASE2.md`** |
@@ -356,6 +359,7 @@ All frontend work is governed by `20-FRONTEND.md`.
 Quick resolver:
 - *"Where is the model / an entity defined?"* → `10-BACKEND-PHASE1.md` (Phase 1) / `12-BACKEND-HRM.md` (HRM) — schema is authoritative there.
 - *"What does this endpoint accept/return?"* → `11-BACKEND-PHASE1.md` (Phase 1) / `13-BACKEND-HRM-API.md` (HRM).
+- *"What does the sales API accept/return?"* → `14-BACKEND-SALES-API.md`.
 - *"How should the UI flow / what do I validate where?"* → `20-FRONTEND.md` (Phase 1) / `21-FRONTEND-HRM.md` (HRM).
 - *"What security risks / checks apply to this feature?"* → `02-SECURITY.md`.
 

docs/01-DOC-GUIDE.md

@@ -39,6 +39,7 @@
 | `12-BACKEND-HRM.md` | High | HRM backend spec: SRS, ER model, HRM-specific architecture notes. Schema is **authoritative** here. | Any HRM model / business-rule / requirement work (Phase 2). | Claude + humans |
 | `13-BACKEND-HRM-API.md` | High | HRM **API reference**: every endpoint, error catalog additions, enums. | Any HRM API contract / controller work. | Claude + humans |
 | `12-GENERAL-LEDGER-INTEGRATION.md` | High | ERPCore ↔ external **General Ledger service**: connection/proxy contract, config, progress. GL's own endpoint contract lives in the GL service's own repo, not here. | Any work touching the GL proxy or a future internal GL caller. | Claude + humans |
+| `14-BACKEND-SALES-API.md` | High | Sales **API reference**: invoices, slips, free issues, reports, enums. | Any sales API contract / controller work. | Claude + humans |
 | `20-FRONTEND.md` | High | Frontend **user-flows**, architecture rules to follow, **validation posture**. | Any frontend work (Phase 1). | Claude + humans |
 | `21-FRONTEND-HRM.md` | High | HRM frontend **user-flows**, screens, validation specifics. | Any HRM frontend work. | Claude + humans |
 | `30-BACKEND-PHASE2.md` | High | Manufacturing (Production Lines) backend: SRS, ER model, status machines, stock/costing integration, **and** the full API contract — model and API in one doc, unlike Phase 1. Schema is **authoritative** here. | Any manufacturing model / rule / API work. | Claude + humans |
@@ -197,7 +198,7 @@ Spec: docs/20-FRONTEND.md (flows + rules) · docs/11-BACKEND-PHASE1.md (API cont
 ## 7. Adding future docs
 
 When later phases arrive (Sales & CRM, Manufacturing, QC/QA, Accounting), follow the same scheme HRM (Phase 2) established:
-- Backend spec/API for a phase → new `1x-` files continuing the backend decade (e.g. HRM used `12-BACKEND-HRM.md` + `13-BACKEND-HRM-API.md`, mirroring the `10`/`11` SRS+ER / API-reference split), linked from the hub.
+- Backend spec/API for a phase → new `1x-` files continuing the backend decade (e.g. HRM used `12-BACKEND-HRM.md` + `13-BACKEND-HRM-API.md`; sales now uses `14-BACKEND-SALES-API.md` alongside the existing phase docs), linked from the hub.
 - Frontend additions → extend `20-FRONTEND.md` or add `2x-` files (e.g. HRM used `21-FRONTEND-HRM.md`).
 - Always register the new doc in `00-CORE.md` routing (§7) and in this index (§2).
 

docs/14-BACKEND-SALES-API.md

@@ -0,0 +1,224 @@
+# 14 · BACKEND — Sales API Reference
+
+> **Authoritative for:** sales API contracts for invoices, slips, free issues, and sales reports.
+> **Navigation:** start from `00-CORE.md`. Sales business rules live in `docs/SALES_MODULE_PLAN.md` and the sales-related backend progress is tracked in `Backend/PROGRESS.md`.
+> **Scope:** this document covers the sales endpoints currently implemented in ERPCore. Free issue is modeled as a sales-slip alias, not a separate table.
+
+---
+
+## 1. Conventions
+
+- Base URL: `https://{host}/api/v1`
+- Authentication: same as the rest of the v1 API
+- Concurrency: `ETag` / `If-Match` on mutable resources
+- Validation: `ProblemDetails` / `ValidationProblemDetails`
+
+---
+
+## 2. Sales Invoices
+
+### `GET /api/v1/sales-invoices`
+Query:
+- `page`
+- `pageSize`
+- `q`
+- `status`
+- `customerId`
+- `warehouseId`
+
+Returns a paged list of `SalesInvoiceSummaryDto`.
+The current frontend register uses this endpoint directly for the invoice hub view.
+
+### `GET /api/v1/sales-invoices/{salesInvoiceId}`
+Returns `SalesInvoiceDto`.
+The detail page shows the document template and only exposes edit actions when the invoice is `Draft`.
+
+### `POST /api/v1/sales-invoices`
+Creates a draft sales invoice.
+
+Request:
+```json
+{
+  "customerId": 2,
+  "warehouseId": 1,
+  "invoiceType": "B2C",
+  "lines": [
+    {
+      "itemId": 1,
+      "uomId": 1,
+      "warehouseId": 1,
+      "qty": 1,
+      "freeQty": 0,
+      "unitPrice": 100,
+      "allowManualPriceOverride": false,
+      "discountMode": "Percentage",
+      "discountPct": 0,
+      "discountAmount": 0,
+      "discountValue": 0,
+      "taxPct": 0,
+      "isFreeIssue": false,
+      "parentLineId": null
+    }
+  ]
+}
+```
+
+### `PUT /api/v1/sales-invoices/{salesInvoiceId}`
+Updates a draft invoice. Requires `If-Match`.
+
+### `POST /api/v1/sales-invoices/{salesInvoiceId}/post`
+Posts stock out and marks the invoice as `Posted`.
+Before posting, the UI calls `GET /api/v1/sales-invoices/{salesInvoiceId}/posting-check` to show shortages.
+
+### `POST /api/v1/sales-invoices/{salesInvoiceId}/cancel`
+Cancels a draft invoice.
+
+---
+
+## 3. Sales Slips
+
+### `GET /api/v1/sales-slips`
+Query:
+- `page`
+- `pageSize`
+- `q`
+- `status`
+- `customerId`
+- `warehouseId`
+
+Returns a paged list of `SalesSlipSummaryDto`.
+
+### `GET /api/v1/sales-slips/{salesSlipId}`
+Returns `SalesSlipDto`.
+The detail page follows the same document-style layout and draft-only edit behavior as invoices.
+
+### `POST /api/v1/sales-slips`
+Creates a draft sales slip.
+
+Request:
+```json
+{
+  "customerId": 2,
+  "warehouseId": 1,
+  "cashierUserId": 1,
+  "lines": [
+    {
+      "itemId": 1,
+      "uomId": 1,
+      "warehouseId": 1,
+      "qty": 1,
+      "freeQty": 0,
+      "unitPrice": 50,
+      "allowManualPriceOverride": false,
+      "discountMode": "Percentage",
+      "discountPct": 0,
+      "discountAmount": 0,
+      "discountValue": 0,
+      "taxPct": 0,
+      "isFreeIssue": false,
+      "parentLineId": null
+    }
+  ]
+}
+```
+
+### `PUT /api/v1/sales-slips/{salesSlipId}`
+Updates a draft slip. Requires `If-Match`.
+
+### `POST /api/v1/sales-slips/{salesSlipId}/post`
+Posts stock out and marks the slip as `Posted`.
+Before posting, the UI calls `GET /api/v1/sales-slips/{salesSlipId}/posting-check`.
+
+### `POST /api/v1/sales-slips/{salesSlipId}/cancel`
+Cancels a draft slip.
+
+---
+
+## 4. Free Issues
+
+Free issue is a business alias over sales slips.
+There is no separate free-issue table in the current schema.
+
+### `GET /api/v1/free-issues`
+Same contract as `GET /api/v1/sales-slips`.
+
+### `GET /api/v1/free-issues/{freeIssueId}`
+Same contract as `GET /api/v1/sales-slips/{salesSlipId}`.
+
+### `POST /api/v1/free-issues`
+Same contract as `POST /api/v1/sales-slips`.
+
+### `PUT /api/v1/free-issues/{freeIssueId}`
+Same contract as `PUT /api/v1/sales-slips/{salesSlipId}`.
+
+### `POST /api/v1/free-issues/{freeIssueId}/post`
+Same contract as `POST /api/v1/sales-slips/{salesSlipId}/post`.
+
+### `POST /api/v1/free-issues/{freeIssueId}/cancel`
+Same contract as `POST /api/v1/sales-slips/{salesSlipId}/cancel`.
+
+Business rule:
+- free issue is represented by `IsFreeIssue=true` and/or `FreeQty>0`
+- it still posts stock out through the normal slip posting flow
+- the frontend free-issue screen is the main working page for create/list/edit/cancel
+- cancelled free-issue records are hidden from the working list view
+
+---
+
+## 5. Sales Reports
+
+### `GET /api/v1/reports/sales`
+Returns the report catalog.
+
+Response:
+```json
+[
+  {
+    "id": "daily-summary",
+    "name": "Daily Summary",
+    "description": "Aggregated sales by day across posted invoices and slips.",
+    "supportedFilters": ["from", "to"]
+  }
+]
+```
+
+### `GET /api/v1/reports/sales/{reportId}`
+Returns a single report definition by id.
+
+### `POST /api/v1/reports/sales/query`
+Returns the actual report data.
+
+Request:
+```json
+{
+  "reportType": "item-summary",
+  "from": "2026-07-01",
+  "to": "2026-07-28",
+  "itemId": 1,
+  "customerId": null,
+  "warehouseId": 1
+}
+```
+
+Supported report types:
+- `daily-summary`
+- `item-summary`
+- `customer-summary`
+- `warehouse-summary`
+- `discount-summary`
+- `free-issue-summary`
+
+Validation rule:
+- invalid filters for a given report type are rejected
+- unsupported report types are rejected
+- the frontend report page uses the same endpoint for all report types
+- `daily-summary` auto-loads with a default date range in the UI
+- the report results table is rendered from the backend response rows, not hardcoded data
+
+---
+
+## 6. Notes
+
+- The sales report service reads both invoices and slips where relevant.
+- Free issue reporting is derived from the same sales document lines.
+- There is no separate free-issue table in the current schema.

docs/SALES_MODULE_PLAN.md

@@ -229,13 +229,15 @@ When an invoice or slip is posted:
 - `POST /api/v1/sales-slips`
 - `POST /api/v1/sales-slips/{id}/post`
 - `POST /api/v1/sales-slips/{id}/cancel`
-- `GET /api/v1/sales-reports/daily-summary`
-- `GET /api/v1/sales-reports/item-wise`
-- `GET /api/v1/sales-reports/customer-wise`
-- `GET /api/v1/sales-reports/warehouse-wise`
-- `GET /api/v1/sales-reports/discount-summary`
-- `GET /api/v1/sales-reports/free-issue-summary`
-- `GET /api/v1/sales-reports/margin-summary`
+- `GET /api/v1/free-issues`
+- `GET /api/v1/free-issues/{id}`
+- `POST /api/v1/free-issues`
+- `PUT /api/v1/free-issues/{id}`
+- `POST /api/v1/free-issues/{id}/post`
+- `POST /api/v1/free-issues/{id}/cancel`
+- `GET /api/v1/reports/sales`
+- `GET /api/v1/reports/sales/{reportId}`
+- `POST /api/v1/reports/sales/query`
 
 ### Phase 1 Folder / Module Plan
 - `Domain/Entities`
@@ -264,7 +266,7 @@ When an invoice or slip is posted:
 4. Pricing resolver
 5. Discount computation
 6. Free issue handling
-7. Stock posting and ledger integration
+7. Stock posting
 8. Basic sales reports
 9. Controllers and swagger wiring