Add smoke tests for UOM conversions and enhance frontend UOM management

- Implemented smoke tests for UOM directionality, ensuring conversions are one-directional and correctly validated.
- Added tests for receiving and selling items in different UOMs, verifying correct quantity handling and error responses.
- Created a UOM conversions panel in the frontend to allow users to manage UOM conversions for items.
- Introduced hooks for allowed UOMs to optimize fetching and caching of UOM data for document line forms.
- Developed utility functions for consistent UOM formatting and conversion handling across the application.

.gitignore

@@ -30,12 +30,13 @@ yarn-error.log*
 Thumbs.db
 .idea/
 
+# ── Playwright E2E (Testing/e2e) ──────────────────────────────────────
+Testing/e2e/playwright-report/
+Testing/e2e/test-results/
+Testing/e2e/.auth/
+Testing/e2e/blob-report/
+
 # ── Migrations ─────────────────────────────────────────────────────────
-# Reverted 2026-07-31: excluding new EF Core migrations while
-# ErpDbContextModelSnapshot.cs stayed tracked meant every `dotnet ef
-# migrations add` after the initial 4 silently produced a migration git would
-# never see, while the (tracked) snapshot's changes committed normally —
-# so the snapshot kept claiming tables existed that no migration in git
-# history ever created them. Confirmed live: 25 HRM tables + 11 Manufacturing
-# tables were missing from the actual database for exactly this reason.
-# Migrations now stay tracked like any other source file — commit them.
+# Each dev keeps EF Core migrations local; DB schema changes are announced
+# to the team instead of committed, so migration files aren't shared here.
+Migrations/

Backend/ERPCore/Controllers/BundleSalesController.cs

@@ -0,0 +1,80 @@
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+[Route("api/v1/bundle-sales")]
+public sealed class BundleSalesController : ApiControllerBase
+{
+    private readonly IBundleSaleService _bundles;
+
+    public BundleSalesController(IBundleSaleService bundles) => _bundles = bundles;
+
+    [HttpGet("templates")]
+    [ProducesResponseType(typeof(PagedResponse<BundleSaleTemplateSummaryDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<BundleSaleTemplateSummaryDto>>> ListTemplates(
+        [FromQuery] PageQuery query,
+        CancellationToken ct)
+        => Ok(await _bundles.ListTemplatesAsync(query, ct));
+
+    [HttpGet("templates/{bundleSaleTemplateId:int}")]
+    [ProducesResponseType(typeof(BundleSaleTemplateDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<BundleSaleTemplateDto>> GetTemplate(int bundleSaleTemplateId, CancellationToken ct)
+    {
+        var result = await _bundles.GetTemplateAsync(bundleSaleTemplateId, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpGet]
+    [ProducesResponseType(typeof(PagedResponse<BundleSaleSummaryDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<BundleSaleSummaryDto>>> List(
+        [FromQuery] PageQuery query,
+        [FromQuery] BundleSaleStatus? status,
+        [FromQuery] int? customerId,
+        [FromQuery] int? warehouseId,
+        CancellationToken ct)
+        => Ok(await _bundles.ListAsync(query, status, customerId, warehouseId, ct));
+
+    [HttpGet("{bundleSaleId:int}")]
+    [ProducesResponseType(typeof(BundleSaleDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<BundleSaleDto>> GetById(int bundleSaleId, CancellationToken ct)
+    {
+        var result = await _bundles.GetAsync(bundleSaleId, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpGet("{bundleSaleId:int}/posting-check")]
+    [ProducesResponseType(typeof(BundleSalePostingCheckDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<BundleSalePostingCheckDto>> PostingCheck(int bundleSaleId, CancellationToken ct)
+        => Ok(await _bundles.CheckPostingAsync(bundleSaleId, ct));
+
+    [HttpPost]
+    [ProducesResponseType(typeof(BundleSaleDto), StatusCodes.Status201Created)]
+    public async Task<ActionResult<BundleSaleDto>> Create([FromBody] CreateBundleSaleRequest request, CancellationToken ct)
+    {
+        var result = await _bundles.CreateAsync(request, ct);
+        return Created($"/api/v1/bundle-sales/{result.BundleSaleId}", result);
+    }
+
+    [HttpPut("{bundleSaleId:int}")]
+    [ProducesResponseType(typeof(BundleSaleDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<BundleSaleDto>> Update(int bundleSaleId, [FromBody] UpdateBundleSaleRequest request, CancellationToken ct)
+    {
+        return Ok(await _bundles.UpdateAsync(bundleSaleId, request, ct));
+    }
+
+    [HttpPost("{bundleSaleId:int}/post")]
+    [ProducesResponseType(typeof(BundleSaleDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<BundleSaleDto>> Post(int bundleSaleId, CancellationToken ct)
+        => Ok(await _bundles.PostAsync(bundleSaleId, ct));
+
+    [HttpPost("{bundleSaleId:int}/cancel")]
+    [ProducesResponseType(typeof(BundleSaleDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<BundleSaleDto>> Cancel(int bundleSaleId, CancellationToken ct)
+        => Ok(await _bundles.CancelAsync(bundleSaleId, ct));
+}

Backend/ERPCore/Controllers/CustomersController.cs

@@ -0,0 +1,69 @@
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Customers;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+/// <summary>Customer master endpoints for Phase 1 sales.</summary>
+[Route("api/v1/customers")]
+public sealed class CustomersController : ApiControllerBase
+{
+    private readonly ICustomerService _customers;
+
+    public CustomersController(ICustomerService customers) => _customers = customers;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(PagedResponse<CustomerDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<CustomerDto>>> List(
+        [FromQuery] PageQuery query,
+        [FromQuery] EntityStatus? status,
+        [FromQuery] CustomerType? customerType,
+        CancellationToken ct)
+        => Ok(await _customers.ListAsync(query, status, customerType, ct));
+
+    [HttpGet("{customerId:int}")]
+    [ProducesResponseType(typeof(CustomerDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<CustomerDto>> GetById(int customerId, CancellationToken ct)
+    {
+        var result = await _customers.GetAsync(customerId, ct);
+        if (result is null) return NotFound();
+
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpPost]
+    [ProducesResponseType(typeof(CustomerDto), StatusCodes.Status201Created)]
+    [ProducesResponseType(StatusCodes.Status409Conflict)]
+    public async Task<ActionResult<CustomerDto>> Create([FromBody] CreateCustomerRequest request, CancellationToken ct)
+    {
+        var result = await _customers.CreateAsync(request, ct);
+        SetETag(result.RowVersion);
+        return Created($"/api/v1/customers/{result.Value.CustomerId}", result.Value);
+    }
+
+    [HttpPut("{customerId:int}")]
+    [ProducesResponseType(typeof(CustomerDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status409Conflict)]
+    [ProducesResponseType(StatusCodes.Status412PreconditionFailed)]
+    public async Task<ActionResult<CustomerDto>> Update(int customerId, [FromBody] UpdateCustomerRequest request, CancellationToken ct)
+    {
+        var expected = RequireIfMatch();
+        var result = await _customers.UpdateAsync(customerId, request, expected, ct);
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpPatch("{customerId:int}/status")]
+    [ProducesResponseType(StatusCodes.Status204NoContent)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<IActionResult> SetStatus(int customerId, [FromBody] UpdateCustomerStatusRequest request, CancellationToken ct)
+    {
+        await _customers.SetStatusAsync(customerId, request.Status, ct);
+        return NoContent();
+    }
+}

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/ItemsController.cs

@@ -1,6 +1,7 @@
 using ERPCore.Domain.Enums;
 using ERPCore.Dtos.Common;
 using ERPCore.Dtos.Items;
+using ERPCore.Dtos.Uoms;
 using ERPCore.Services.Interfaces;
 using Microsoft.AspNetCore.Mvc;
 
@@ -11,8 +12,13 @@ namespace ERPCore.Controllers;
 public sealed class ItemsController : ApiControllerBase
 {
     private readonly IItemService _items;
+    private readonly IUomConverter _uomConverter;
 
-    public ItemsController(IItemService items) => _items = items;
+    public ItemsController(IItemService items, IUomConverter uomConverter)
+    {
+        _items = items;
+        _uomConverter = uomConverter;
+    }
 
     /// <summary>List items with optional filters and paging.</summary>
     [HttpGet]
@@ -88,4 +94,15 @@ public sealed class ItemsController : ApiControllerBase
     [ProducesResponseType(StatusCodes.Status404NotFound)]
     public async Task<ActionResult<ItemUomConversionsDto>> UpdateUomConversions(int itemId, [FromBody] UpdateUomConversionsRequest request, CancellationToken ct)
         => Ok(await _items.UpdateUomConversionsAsync(itemId, request, ct));
+
+    /// <summary>
+    /// The UOMs this item may be transacted in — its base UOM plus every UOM it has a
+    /// conversion from, each with the factor to base. Document line forms use this to offer
+    /// only units that will survive posting, instead of the whole global UOM list (FR-MD-02/03).
+    /// </summary>
+    [HttpGet("{itemId:int}/uoms")]
+    [ProducesResponseType(typeof(IReadOnlyList<AllowedUomDto>), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<IReadOnlyList<AllowedUomDto>>> GetAllowedUoms(int itemId, CancellationToken ct)
+        => Ok(await _uomConverter.GetAllowedUomsAsync(itemId, ct));
 }

Backend/ERPCore/Controllers/SalesInvoicesController.cs

@@ -0,0 +1,73 @@
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+[Route("api/v1/sales-invoices")]
+public sealed class SalesInvoicesController : ApiControllerBase
+{
+    private readonly ISalesInvoiceService _invoices;
+
+    public SalesInvoicesController(ISalesInvoiceService invoices) => _invoices = invoices;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(PagedResponse<SalesInvoiceSummaryDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<SalesInvoiceSummaryDto>>> List(
+        [FromQuery] PageQuery query,
+        [FromQuery] SalesInvoiceStatus? status,
+        [FromQuery] int? customerId,
+        [FromQuery] int? warehouseId,
+        CancellationToken ct)
+        => Ok(await _invoices.ListAsync(query, status, customerId, warehouseId, ct));
+
+    [HttpGet("{salesInvoiceId:int}")]
+    [ProducesResponseType(typeof(SalesInvoiceDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<SalesInvoiceDto>> GetById(int salesInvoiceId, CancellationToken ct)
+    {
+        var result = await _invoices.GetAsync(salesInvoiceId, ct);
+        if (result is null) return NotFound();
+        SetETag(result.RowVersion);
+        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)
+    {
+        var result = await _invoices.CreateAsync(request, ct);
+        SetETag(result.RowVersion);
+        return Created($"/api/v1/sales-invoices/{result.Value.SalesInvoiceId}", result.Value);
+    }
+
+    [HttpPut("{salesInvoiceId:int}")]
+    [ProducesResponseType(typeof(SalesInvoiceDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status412PreconditionFailed)]
+    public async Task<ActionResult<SalesInvoiceDto>> Update(int salesInvoiceId, [FromBody] UpdateSalesInvoiceRequest request, CancellationToken ct)
+    {
+        var expected = RequireIfMatch();
+        var result = await _invoices.UpdateAsync(salesInvoiceId, request, expected, ct);
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpPost("{salesInvoiceId:int}/post")]
+    [ProducesResponseType(typeof(SalesInvoiceDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<SalesInvoiceDto>> Post(int salesInvoiceId, CancellationToken ct)
+        => Ok(await _invoices.PostAsync(salesInvoiceId, ct));
+
+    [HttpPost("{salesInvoiceId:int}/cancel")]
+    [ProducesResponseType(typeof(SalesInvoiceDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<SalesInvoiceDto>> Cancel(int salesInvoiceId, CancellationToken ct)
+        => Ok(await _invoices.CancelAsync(salesInvoiceId, ct));
+}

Backend/ERPCore/Controllers/SalesReportsController.cs

@@ -0,0 +1,35 @@
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+[Route("api/v1/reports/sales")]
+public sealed class SalesReportsController : ApiControllerBase
+{
+    private readonly ISalesReportService _reports;
+
+    public SalesReportsController(ISalesReportService reports) => _reports = reports;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(IReadOnlyList<SalesReportDefinitionDto>), StatusCodes.Status200OK)]
+    public ActionResult<IReadOnlyList<SalesReportDefinitionDto>> ListReports()
+        => Ok(_reports.ListReports());
+
+    [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);
+    }
+
+    [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

@@ -0,0 +1,73 @@
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ERPCore.Controllers;
+
+[Route("api/v1/sales-slips")]
+public sealed class SalesSlipsController : ApiControllerBase
+{
+    private readonly ISalesSlipService _slips;
+
+    public SalesSlipsController(ISalesSlipService slips) => _slips = slips;
+
+    [HttpGet]
+    [ProducesResponseType(typeof(PagedResponse<SalesSlipSummaryDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<SalesSlipSummaryDto>>> List(
+        [FromQuery] PageQuery query,
+        [FromQuery] SalesSlipStatus? status,
+        [FromQuery] int? customerId,
+        [FromQuery] int? warehouseId,
+        CancellationToken ct)
+        => Ok(await _slips.ListAsync(query, status, customerId, warehouseId, ct));
+
+    [HttpGet("{salesSlipId:int}")]
+    [ProducesResponseType(typeof(SalesSlipDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<ActionResult<SalesSlipDto>> GetById(int salesSlipId, CancellationToken ct)
+    {
+        var result = await _slips.GetAsync(salesSlipId, ct);
+        if (result is null) return NotFound();
+        SetETag(result.RowVersion);
+        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)
+    {
+        var result = await _slips.CreateAsync(request, ct);
+        SetETag(result.RowVersion);
+        return Created($"/api/v1/sales-slips/{result.Value.SalesSlipId}", result.Value);
+    }
+
+    [HttpPut("{salesSlipId:int}")]
+    [ProducesResponseType(typeof(SalesSlipDto), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status412PreconditionFailed)]
+    public async Task<ActionResult<SalesSlipDto>> Update(int salesSlipId, [FromBody] UpdateSalesSlipRequest request, CancellationToken ct)
+    {
+        var expected = RequireIfMatch();
+        var result = await _slips.UpdateAsync(salesSlipId, request, expected, ct);
+        SetETag(result.RowVersion);
+        return Ok(result.Value);
+    }
+
+    [HttpPost("{salesSlipId:int}/post")]
+    [ProducesResponseType(typeof(SalesSlipDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<SalesSlipDto>> Post(int salesSlipId, CancellationToken ct)
+        => Ok(await _slips.PostAsync(salesSlipId, ct));
+
+    [HttpPost("{salesSlipId:int}/cancel")]
+    [ProducesResponseType(typeof(SalesSlipDto), StatusCodes.Status200OK)]
+    public async Task<ActionResult<SalesSlipDto>> Cancel(int salesSlipId, CancellationToken ct)
+        => Ok(await _slips.CancelAsync(salesSlipId, ct));
+}

Backend/ERPCore/Domain/DocumentTypes.cs

@@ -17,4 +17,7 @@ public static class DocumentTypes
 
     /// <summary>Production run (docs/30 FR-MFG-08) — <c>PRD-2026-00001</c>.</summary>
     public const string Production = "PRD";
+    public const string SalesInvoice = "SI";
+    public const string SalesSlip = "SSL";
+    public const string BundleSale = "BND";
 }

Backend/ERPCore/Domain/Entities/BundleSale.cs

@@ -0,0 +1,33 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class BundleSale
+{
+    public int BundleSaleId { get; set; }
+    public string BundleNo { get; set; } = string.Empty;
+    public DateTime BundleDate { get; set; }
+    public int CustomerId { get; set; }
+    public Customer? Customer { get; set; }
+    public string CustomerSnapshotName { get; set; } = string.Empty;
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+    public int CashierUserId { get; set; }
+    public User? CashierUser { get; set; }
+    public int BundleSaleTemplateId { get; set; }
+    public BundleSaleTemplate? BundleSaleTemplate { get; set; }
+    public string BundleName { get; set; } = string.Empty;
+    public string BundleCode { get; set; } = string.Empty;
+    public BundleSaleStatus Status { get; set; } = BundleSaleStatus.Draft;
+    public decimal ComponentSubtotal { get; set; }
+    public decimal BundlePrice { get; set; }
+    public decimal MarginAmount { get; set; }
+    public decimal DiscountTotal { get; set; }
+    public decimal TaxTotal { get; set; }
+    public decimal GrandTotal { get; set; }
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+    public int ConcurrencyStamp { get; set; }
+
+    public ICollection<BundleSaleLine> Lines { get; set; } = new List<BundleSaleLine>();
+}

Backend/ERPCore/Domain/Entities/BundleSaleLine.cs

@@ -0,0 +1,35 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class BundleSaleLine
+{
+    public int BundleSaleLineId { get; set; }
+    public int BundleSaleId { get; set; }
+    public BundleSale? BundleSale { get; set; }
+
+    public int ItemId { get; set; }
+    public Item? Item { get; set; }
+    public string Description { get; set; } = string.Empty;
+    /// <summary>Component quantity, in <see cref="UomId"/> — what the user entered.</summary>
+    public decimal Qty { get; set; }
+    public int UomId { get; set; }
+    public Uom? Uom { get; set; }
+
+    /// <summary>
+    /// <see cref="Qty"/> restated in the item's base UOM, resolved once at save. Posting
+    /// consumes this. <see cref="Qty"/> and <see cref="UnitPrice"/> are always a matching
+    /// pair in <see cref="UomId"/>, so <see cref="LineTotal"/> stays value-correct.
+    /// </summary>
+    public decimal QtyBase { get; set; }
+
+    /// <summary>The factor used to derive <see cref="QtyBase"/>; 1 when the line is in base UOM.</summary>
+    public decimal ConversionFactor { get; set; } = 1m;
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+    public decimal UnitPrice { get; set; }
+    public decimal LineTotal { get; set; }
+    public bool IncludeInBundle { get; set; } = true;
+    public bool IsComponent { get; set; } = true;
+    public int? ParentLineId { get; set; }
+}

Backend/ERPCore/Domain/Entities/BundleSaleTemplate.cs

@@ -0,0 +1,17 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class BundleSaleTemplate
+{
+    public int BundleSaleTemplateId { get; set; }
+    public string TemplateCode { get; set; } = string.Empty;
+    public string TemplateName { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public EntityStatus Status { get; set; } = EntityStatus.Active;
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+    public int ConcurrencyStamp { get; set; }
+
+    public ICollection<BundleSaleTemplateLine> Lines { get; set; } = new List<BundleSaleTemplateLine>();
+}

Backend/ERPCore/Domain/Entities/BundleSaleTemplateLine.cs

@@ -0,0 +1,20 @@
+namespace ERPCore.Domain.Entities;
+
+public class BundleSaleTemplateLine
+{
+    public int BundleSaleTemplateLineId { get; set; }
+    public int BundleSaleTemplateId { get; set; }
+    public BundleSaleTemplate? BundleSaleTemplate { get; set; }
+
+    public int ItemId { get; set; }
+    public Item? Item { get; set; }
+    public int UomId { get; set; }
+    public Uom? Uom { get; set; }
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+
+    public decimal Qty { get; set; }
+    public decimal UnitPrice { get; set; }
+    public bool IncludeInBundle { get; set; } = true;
+    public int SortOrder { get; set; }
+}

Backend/ERPCore/Domain/Entities/Customer.cs

@@ -0,0 +1,38 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// Customer master for both B2B and B2C sales.
+/// Phase 1 keeps this lean: identity, contact, tax, credit, and default warehouse.
+/// </summary>
+public class Customer
+{
+    public int CustomerId { get; set; }
+    public string CustomerCode { get; set; } = string.Empty;
+    public CustomerType CustomerType { get; set; } = CustomerType.B2C;
+
+    public string Name { get; set; } = string.Empty;
+    public string? DisplayName { get; set; }
+    public string? Phone { get; set; }
+    public string? Email { get; set; }
+
+    public string? AddressLine1 { get; set; }
+    public string? AddressLine2 { get; set; }
+    public string? City { get; set; }
+    public string? Country { get; set; }
+
+    public string? TaxRegistrationNo { get; set; }
+    public decimal CreditLimit { get; set; }
+    public int CreditDays { get; set; }
+
+    public int? DefaultWarehouseId { get; set; }
+    public Warehouse? DefaultWarehouse { get; set; }
+
+    public EntityStatus Status { get; set; } = EntityStatus.Active;
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+
+    /// <summary>PostgreSQL xmin-backed optimistic concurrency token (ETag source).</summary>
+    public uint RowVersion { get; set; }
+}

Backend/ERPCore/Domain/Entities/GrnLine.cs

@@ -34,8 +34,20 @@ public class GrnLine
     public int? BatchId { get; set; }
     public Batch? Batch { get; set; }
 
+    /// <summary>Quantity received, in <see cref="UomId"/> — what the user entered.</summary>
     public decimal Qty { get; set; }
 
+    /// <summary>
+    /// <see cref="Qty"/> restated in the item's base UOM, resolved once at line creation.
+    /// Confirm reads this snapshot rather than re-converting, so a conversion factor edited
+    /// between create and confirm cannot change what a saved GRN posts, and a later reversal
+    /// reproduces the original layer exactly.
+    /// </summary>
+    public decimal QtyBase { get; set; }
+
+    /// <summary>The factor used to derive <see cref="QtyBase"/>; 1 when the line is in base UOM.</summary>
+    public decimal ConversionFactor { get; set; } = 1m;
+
     /// <summary>Gross unit cost received at (entered, or PO price when omitted).</summary>
     public decimal UnitCost { get; set; }
 

Backend/ERPCore/Domain/Entities/PoLine.cs

@@ -21,8 +21,32 @@ public class PoLine
     public int WarehouseId { get; set; }
     public Warehouse? Warehouse { get; set; }
 
+    /// <summary>Quantity ordered, in <see cref="UomId"/>.</summary>
     public decimal Qty { get; set; }
     public decimal UnitPrice { get; set; }//
     public decimal Tax { get; set; }
+
+    /// <summary>
+    /// <see cref="Qty"/> restated in the item's base UOM, resolved once at line creation.
+    /// This — not <see cref="Qty"/> — is what open-quantity and close checks compare against,
+    /// because a GRN may legitimately receive against this line in a different UOM.
+    /// </summary>
+    public decimal QtyBase { get; set; }
+
+    /// <summary>The factor used to derive <see cref="QtyBase"/>; 1 when the line is in base UOM.</summary>
+    public decimal ConversionFactor { get; set; } = 1m;
+
+    /// <summary>
+    /// Accrues as GRNs confirm (FR-PROC-07), in <see cref="UomId"/>. <b>Denormalized for
+    /// display only</b> — it is derived by dividing <see cref="QtyReceivedBase"/> by the
+    /// factor, so it can drift. Never branch on it; use <see cref="QtyReceivedBase"/>.
+    /// </summary>
     public decimal QtyReceived { get; set; }
+
+    /// <summary>
+    /// Authoritative received-to-date in the item's base UOM. GRN confirm accrues here and
+    /// the PO close condition compares this against <see cref="QtyBase"/>, so receipts in a
+    /// UOM other than the PO's still add up correctly.
+    /// </summary>
+    public decimal QtyReceivedBase { get; set; }
 }

Backend/ERPCore/Domain/Entities/SalesInvoice.cs

@@ -0,0 +1,41 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class SalesInvoice
+{
+    public int SalesInvoiceId { get; set; }
+    public string InvoiceNo { get; set; } = string.Empty;
+    public DateTime InvoiceDate { get; set; }
+
+    public int CustomerId { get; set; }
+    public Customer? Customer { get; set; }
+
+    public string CustomerSnapshotName { get; set; } = string.Empty;
+    public string? CustomerSnapshotTaxNo { get; set; }
+
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+
+    public SalesInvoiceType InvoiceType { get; set; } = SalesInvoiceType.B2C;
+    public SalesInvoiceStatus Status { get; set; } = SalesInvoiceStatus.Draft;
+
+    public decimal Subtotal { get; set; }
+    public decimal DiscountTotal { get; set; }
+    public decimal TaxTotal { get; set; }
+    public decimal GrandTotal { get; set; }
+    public decimal RoundOff { get; set; }
+    public decimal NetPayable { get; set; }
+    public decimal PaidAmount { get; set; }
+    public decimal BalanceAmount { get; set; }
+
+    public int CreatedBy { get; set; }
+    public User? Creator { get; set; }
+
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+
+    public uint RowVersion { get; set; }
+
+    public ICollection<SalesInvoiceLine> Lines { get; set; } = new List<SalesInvoiceLine>();
+}

Backend/ERPCore/Domain/Entities/SalesInvoiceLine.cs

@@ -0,0 +1,52 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class SalesInvoiceLine
+{
+    public int SalesInvoiceLineId { get; set; }
+
+    public int SalesInvoiceId { get; set; }
+    public SalesInvoice? SalesInvoice { get; set; }
+
+    public int ItemId { get; set; }
+    public Item? Item { get; set; }
+
+    public string Description { get; set; } = string.Empty;
+
+    /// <summary>Quantity sold, in <see cref="UomId"/> — what the user entered and what prints.</summary>
+    public decimal Qty { get; set; }
+    public decimal FreeQty { get; set; }
+    public int UomId { get; set; }
+    public Uom? Uom { get; set; }
+
+    /// <summary>
+    /// <see cref="Qty"/> restated in the item's base UOM, resolved once at save. Posting
+    /// consumes stock against this snapshot — the FIFO engine is base-UOM only, so passing
+    /// the entered quantity would deplete the wrong amount whenever the line is not in base UOM.
+    /// </summary>
+    public decimal QtyBase { get; set; }
+
+    /// <summary><see cref="FreeQty"/> restated in the item's base UOM.</summary>
+    public decimal FreeQtyBase { get; set; }
+
+    /// <summary>The factor used to derive the base quantities; 1 when the line is in base UOM.</summary>
+    public decimal ConversionFactor { get; set; } = 1m;
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+
+    public decimal UnitPrice { get; set; }
+    public decimal BaseCost { get; set; }
+    public string PriceSource { get; set; } = string.Empty;
+    public SalesDiscountMode DiscountMode { get; set; } = SalesDiscountMode.Percentage;
+    public decimal DiscountPct { get; set; }
+    public decimal DiscountAmount { get; set; }
+    public decimal NetUnitPrice { get; set; }
+    public decimal LineTotal { get; set; }
+    public decimal TaxPct { get; set; }
+    public decimal TaxAmount { get; set; }
+    public bool IsFreeIssue { get; set; }
+    public int? ParentLineId { get; set; }
+
+    public uint RowVersion { get; set; }
+}

Backend/ERPCore/Domain/Entities/SalesSlip.cs

@@ -0,0 +1,36 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class SalesSlip
+{
+    public int SalesSlipId { get; set; }
+    public string SlipNo { get; set; } = string.Empty;
+    public DateTime SlipDate { get; set; }
+
+    public int CustomerId { get; set; }
+    public Customer? Customer { get; set; }
+
+    public string CustomerSnapshotName { get; set; } = string.Empty;
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+
+    public int CashierUserId { get; set; }
+    public User? CashierUser { get; set; }
+
+    public SalesSlipStatus Status { get; set; } = SalesSlipStatus.Draft;
+
+    public decimal Subtotal { get; set; }
+    public decimal DiscountTotal { get; set; }
+    public decimal TaxTotal { get; set; }
+    public decimal GrandTotal { get; set; }
+    public decimal PaidAmount { get; set; }
+    public decimal BalanceAmount { get; set; }
+
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+
+    public uint RowVersion { get; set; }
+
+    public ICollection<SalesSlipLine> Lines { get; set; } = new List<SalesSlipLine>();
+}

Backend/ERPCore/Domain/Entities/SalesSlipLine.cs

@@ -0,0 +1,52 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+public class SalesSlipLine
+{
+    public int SalesSlipLineId { get; set; }
+
+    public int SalesSlipId { get; set; }
+    public SalesSlip? SalesSlip { get; set; }
+
+    public int ItemId { get; set; }
+    public Item? Item { get; set; }
+
+    public string Description { get; set; } = string.Empty;
+
+    /// <summary>Quantity sold, in <see cref="UomId"/> — what the user entered and what prints.</summary>
+    public decimal Qty { get; set; }
+    public decimal FreeQty { get; set; }
+    public int UomId { get; set; }
+    public Uom? Uom { get; set; }
+
+    /// <summary>
+    /// <see cref="Qty"/> restated in the item's base UOM, resolved once at save. Posting
+    /// consumes stock against this snapshot — the FIFO engine is base-UOM only, so passing
+    /// the entered quantity would deplete the wrong amount whenever the line is not in base UOM.
+    /// </summary>
+    public decimal QtyBase { get; set; }
+
+    /// <summary><see cref="FreeQty"/> restated in the item's base UOM.</summary>
+    public decimal FreeQtyBase { get; set; }
+
+    /// <summary>The factor used to derive the base quantities; 1 when the line is in base UOM.</summary>
+    public decimal ConversionFactor { get; set; } = 1m;
+    public int WarehouseId { get; set; }
+    public Warehouse? Warehouse { get; set; }
+
+    public decimal UnitPrice { get; set; }
+    public decimal BaseCost { get; set; }
+    public string PriceSource { get; set; } = string.Empty;
+    public SalesDiscountMode DiscountMode { get; set; } = SalesDiscountMode.Percentage;
+    public decimal DiscountPct { get; set; }
+    public decimal DiscountAmount { get; set; }
+    public decimal NetUnitPrice { get; set; }
+    public decimal LineTotal { get; set; }
+    public decimal TaxPct { get; set; }
+    public decimal TaxAmount { get; set; }
+    public bool IsFreeIssue { get; set; }
+    public int? ParentLineId { get; set; }
+
+    public uint RowVersion { get; set; }
+}

Backend/ERPCore/Domain/Enums/BundleSaleStatus.cs

@@ -0,0 +1,8 @@
+namespace ERPCore.Domain.Enums;
+
+public enum BundleSaleStatus
+{
+    Draft = 0,
+    Posted = 1,
+    Cancelled = 2
+}

Backend/ERPCore/Domain/Enums/CustomerType.cs

@@ -0,0 +1,8 @@
+namespace ERPCore.Domain.Enums;
+
+public enum CustomerType
+{
+    B2B = 1,
+    B2C = 2,
+    WalkIn = 3
+}

Backend/ERPCore/Domain/Enums/SalesDiscountMode.cs

@@ -0,0 +1,7 @@
+namespace ERPCore.Domain.Enums;
+
+public enum SalesDiscountMode
+{
+    Percentage = 1,
+    Amount = 2
+}

Backend/ERPCore/Domain/Enums/SalesInvoiceStatus.cs

@@ -0,0 +1,8 @@
+namespace ERPCore.Domain.Enums;
+
+public enum SalesInvoiceStatus
+{
+    Draft = 1,
+    Posted = 2,
+    Cancelled = 3
+}

Backend/ERPCore/Domain/Enums/SalesInvoiceType.cs

@@ -0,0 +1,9 @@
+namespace ERPCore.Domain.Enums;
+
+public enum SalesInvoiceType
+{
+    B2B = 1,
+    B2C = 2,
+    Cash = 3,
+    Credit = 4
+}

Backend/ERPCore/Domain/Enums/SalesSlipStatus.cs

@@ -0,0 +1,8 @@
+namespace ERPCore.Domain.Enums;
+
+public enum SalesSlipStatus
+{
+    Draft = 1,
+    Posted = 2,
+    Cancelled = 3
+}

Backend/ERPCore/Dtos/Customers/CustomerDtos.cs

@@ -0,0 +1,66 @@
+using System.ComponentModel.DataAnnotations;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Dtos.Customers;
+
+/// <summary>Customer resource used by sales documents.</summary>
+public sealed record CustomerDto(
+    int CustomerId,
+    string CustomerCode,
+    CustomerType CustomerType,
+    string Name,
+    string? DisplayName,
+    string? Phone,
+    string? Email,
+    string? AddressLine1,
+    string? AddressLine2,
+    string? City,
+    string? Country,
+    string? TaxRegistrationNo,
+    decimal CreditLimit,
+    int CreditDays,
+    int? DefaultWarehouseId,
+    EntityStatus Status,
+    DateTime CreatedAt,
+    DateTime? UpdatedAt);
+
+public sealed class CreateCustomerRequest
+{
+    [Required, StringLength(50)] public string CustomerCode { get; set; } = string.Empty;
+    [Required, EnumDataType(typeof(CustomerType))] public CustomerType CustomerType { get; set; } = CustomerType.B2C;
+    [Required, StringLength(200)] public string Name { get; set; } = string.Empty;
+    [StringLength(200)] public string? DisplayName { get; set; }
+    [StringLength(30)] public string? Phone { get; set; }
+    [StringLength(100)] public string? Email { get; set; }
+    [StringLength(250)] public string? AddressLine1 { get; set; }
+    [StringLength(250)] public string? AddressLine2 { get; set; }
+    [StringLength(100)] public string? City { get; set; }
+    [StringLength(100)] public string? Country { get; set; }
+    [StringLength(50)] public string? TaxRegistrationNo { get; set; }
+    [Range(0, double.MaxValue)] public decimal CreditLimit { get; set; }
+    [Range(0, int.MaxValue)] public int CreditDays { get; set; }
+    public int? DefaultWarehouseId { get; set; }
+}
+
+public sealed class UpdateCustomerRequest
+{
+    [Required, StringLength(50)] public string CustomerCode { get; set; } = string.Empty;
+    [Required, EnumDataType(typeof(CustomerType))] public CustomerType CustomerType { get; set; } = CustomerType.B2C;
+    [Required, StringLength(200)] public string Name { get; set; } = string.Empty;
+    [StringLength(200)] public string? DisplayName { get; set; }
+    [StringLength(30)] public string? Phone { get; set; }
+    [StringLength(100)] public string? Email { get; set; }
+    [StringLength(250)] public string? AddressLine1 { get; set; }
+    [StringLength(250)] public string? AddressLine2 { get; set; }
+    [StringLength(100)] public string? City { get; set; }
+    [StringLength(100)] public string? Country { get; set; }
+    [StringLength(50)] public string? TaxRegistrationNo { get; set; }
+    [Range(0, double.MaxValue)] public decimal CreditLimit { get; set; }
+    [Range(0, int.MaxValue)] public int CreditDays { get; set; }
+    public int? DefaultWarehouseId { get; set; }
+}
+
+public sealed class UpdateCustomerStatusRequest
+{
+    [Required, EnumDataType(typeof(EntityStatus))] public EntityStatus Status { get; set; }
+}

Backend/ERPCore/Dtos/Procurement/PurchaseOrderDtos.cs

@@ -5,9 +5,18 @@ namespace ERPCore.Dtos.Procurement;
 
 // Responses (docs/11 §3.3) ------------------------------------------------------
 
+/// <summary>
+/// A PO line. <paramref name="Qty"/> and <paramref name="QtyReceived"/> are in
+/// <paramref name="UomId"/> and are what the user sees; <paramref name="QtyBase"/> and
+/// <paramref name="QtyReceivedBase"/> are the item's base UOM and are what the server
+/// actually enforces — GRN over-receipt and the PO close condition both run on the base
+/// pair, because goods may legitimately be received in a different UOM from the one
+/// ordered. A client showing remaining/outstanding quantity should read the base pair.
+/// </summary>
 public sealed record PoLineDto(
     int PoLineId, int ItemId, int UomId, int WarehouseId,
-    decimal Qty, decimal UnitPrice, decimal Tax, decimal QtyReceived);
+    decimal Qty, decimal UnitPrice, decimal Tax, decimal QtyReceived,
+    decimal QtyBase = 0m, decimal QtyReceivedBase = 0m, decimal ConversionFactor = 1m);
 
 public sealed record PoTotalsDto(decimal SubTotal, decimal Tax, decimal GrandTotal, string Currency);
 

Backend/ERPCore/Dtos/Sales/BundleSaleDtos.cs

@@ -0,0 +1,84 @@
+using System.ComponentModel.DataAnnotations;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Dtos.Sales;
+
+public sealed record BundleSaleLineDto(
+    int BundleSaleLineId, int ItemId, string Description, decimal Qty, int UomId, int WarehouseId,
+    decimal UnitPrice, decimal LineTotal, bool IncludeInBundle, bool IsComponent, int? ParentLineId);
+
+public sealed record BundleSaleDto(
+    int BundleSaleId, string BundleNo, DateTime BundleDate, int CustomerId, string CustomerSnapshotName,
+    int WarehouseId, int CashierUserId, int BundleSaleTemplateId, string BundleName, string BundleCode,
+    BundleSaleStatus Status, decimal ComponentSubtotal, decimal BundlePrice, decimal MarginAmount,
+    decimal DiscountTotal, decimal TaxTotal, decimal GrandTotal, DateTime CreatedAt, DateTime? UpdatedAt,
+    IReadOnlyList<BundleSaleLineDto> Lines);
+
+public sealed record BundleSaleSummaryDto(
+    int BundleSaleId, string BundleNo, DateTime BundleDate, int CustomerId, string CustomerSnapshotName,
+    int WarehouseId, string BundleName, string BundleCode, BundleSaleStatus Status,
+    decimal ComponentSubtotal, decimal BundlePrice, decimal GrandTotal, DateTime CreatedAt);
+
+public sealed record BundleSaleTemplateLineDto(
+    int BundleSaleTemplateLineId, int ItemId, int UomId, int WarehouseId, decimal Qty,
+    decimal UnitPrice, bool IncludeInBundle, int SortOrder);
+
+public sealed record BundleSaleTemplateDto(
+    int BundleSaleTemplateId, string TemplateCode, string TemplateName, string? Description,
+    EntityStatus Status, DateTime CreatedAt, DateTime? UpdatedAt, IReadOnlyList<BundleSaleTemplateLineDto> Lines);
+
+public sealed record BundleSaleTemplateSummaryDto(
+    int BundleSaleTemplateId, string TemplateCode, string TemplateName, string? Description,
+    EntityStatus Status, int LineCount, DateTime CreatedAt, DateTime? UpdatedAt);
+
+/// <summary>Quantities are in the item's base UOM — see <c>SalesInvoicePostingIssueDto</c>.</summary>
+public sealed record BundleSalePostingIssueDto(
+    int BundleSaleLineId, int ItemId, string ItemSku, string ItemName, int WarehouseId,
+    decimal RequestedQty, decimal AvailableQty, decimal ShortQty, string BaseUomName = "");
+
+public sealed record BundleSalePostingCheckDto(
+    int BundleSaleId, string BundleNo, BundleSaleStatus Status, bool CanPost,
+    IReadOnlyList<BundleSalePostingIssueDto> Issues);
+
+public sealed class CreateBundleSaleTemplateLineRequest
+{
+    [Required] public int ItemId { get; set; }
+    [Required] public int UomId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Range(0.0001, double.MaxValue)] public decimal Qty { get; set; }
+    [Range(0, double.MaxValue)] public decimal UnitPrice { get; set; }
+    public bool IncludeInBundle { get; set; } = true;
+    public int SortOrder { get; set; }
+}
+
+public sealed class CreateBundleSaleTemplateRequest
+{
+    [Required] public string TemplateCode { get; set; } = string.Empty;
+    [Required] public string TemplateName { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    [Required, MinLength(1)] public List<CreateBundleSaleTemplateLineRequest> Lines { get; set; } = new();
+}
+
+public sealed class CreateBundleSaleRequest
+{
+    [Required] public int CustomerId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Required] public int CashierUserId { get; set; }
+    [Required] public int BundleSaleTemplateId { get; set; }
+    [Required] public string BundleName { get; set; } = string.Empty;
+    [Range(0, double.MaxValue)] public decimal BundlePrice { get; set; }
+    public bool AllowPriceOverride { get; set; }
+    [Required, MinLength(1)] public List<CreateBundleSaleTemplateLineRequest> Lines { get; set; } = new();
+}
+
+public sealed class UpdateBundleSaleRequest
+{
+    [Required] public int CustomerId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Required] public int CashierUserId { get; set; }
+    [Required] public int BundleSaleTemplateId { get; set; }
+    [Required] public string BundleName { get; set; } = string.Empty;
+    [Range(0, double.MaxValue)] public decimal BundlePrice { get; set; }
+    public bool AllowPriceOverride { get; set; }
+    [Required, MinLength(1)] public List<CreateBundleSaleTemplateLineRequest> Lines { get; set; } = new();
+}

Backend/ERPCore/Dtos/Sales/SalesInvoiceDtos.cs

@@ -0,0 +1,74 @@
+using System.ComponentModel.DataAnnotations;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Dtos.Sales;
+
+public sealed record SalesInvoiceLineDto(
+    int SalesInvoiceLineId, int ItemId, string Description, decimal Qty, decimal FreeQty, int UomId,
+    int WarehouseId, decimal UnitPrice, decimal BaseCost, string PriceSource, decimal DiscountPct,
+    decimal DiscountAmount, SalesDiscountMode DiscountMode, decimal NetUnitPrice, decimal LineTotal,
+    decimal TaxPct, decimal TaxAmount, bool IsFreeIssue, int? ParentLineId);
+
+public sealed record SalesInvoiceTotalsDto(
+    decimal Subtotal, decimal DiscountTotal, decimal FreeQtyTotal, decimal TaxTotal, decimal GrandTotal,
+    decimal RoundOff, decimal NetPayable, decimal PaidAmount, decimal BalanceAmount);
+
+public sealed record SalesInvoiceDto(
+    int SalesInvoiceId, string InvoiceNo, DateTime InvoiceDate, int CustomerId,
+    string CustomerSnapshotName, string? CustomerSnapshotTaxNo, int WarehouseId,
+    SalesInvoiceType InvoiceType, SalesInvoiceStatus Status, int CreatedBy, DateTime CreatedAt,
+    DateTime? UpdatedAt, SalesInvoiceTotalsDto Totals, IReadOnlyList<SalesInvoiceLineDto> Lines);
+
+public sealed record SalesInvoiceSummaryDto(
+    int SalesInvoiceId, string InvoiceNo, DateTime InvoiceDate, int CustomerId,
+    string CustomerSnapshotName, int WarehouseId, SalesInvoiceType InvoiceType,
+    SalesInvoiceStatus Status, SalesInvoiceTotalsDto Totals, DateTime CreatedAt);
+
+/// <summary>
+/// A line that cannot be posted for lack of stock. The three quantities are in the item's
+/// <b>base</b> UOM (on-hand only exists in base), which may differ from the UOM shown on the
+/// line — hence <paramref name="BaseUomName"/>: without it a line reading "2 BOX" produces
+/// an unexplained "requested 24, available 10".
+/// </summary>
+public sealed record SalesInvoicePostingIssueDto(
+    int SalesInvoiceLineId, int ItemId, string ItemSku, string ItemName, int WarehouseId,
+    decimal RequestedQty, decimal AvailableQty, decimal ShortQty, bool IsFreeIssue,
+    string BaseUomName = "");
+
+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; }
+    [Required] public int UomId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Range(0.0001, double.MaxValue)] public decimal Qty { get; set; }
+    [Range(0, double.MaxValue)] public decimal FreeQty { get; set; }
+    [Range(0, double.MaxValue)] public decimal? UnitPrice { get; set; }
+    public bool AllowManualPriceOverride { get; set; }
+    [Required, EnumDataType(typeof(SalesDiscountMode))] public SalesDiscountMode DiscountMode { get; set; } = SalesDiscountMode.Percentage;
+    [Range(0, 100)] public decimal DiscountPct { get; set; }
+    [Range(0, double.MaxValue)] public decimal DiscountAmount { get; set; }
+    [Range(0, double.MaxValue)] public decimal DiscountValue { get; set; }
+    [Range(0, 100)] public decimal TaxPct { get; set; }
+    public bool IsFreeIssue { get; set; }
+    public int? ParentLineId { get; set; }
+}
+
+public sealed class CreateSalesInvoiceRequest
+{
+    [Required] public int CustomerId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Required, EnumDataType(typeof(SalesInvoiceType))] public SalesInvoiceType InvoiceType { get; set; } = SalesInvoiceType.B2C;
+    [Required, MinLength(1)] public List<CreateSalesInvoiceLineRequest> Lines { get; set; } = new();
+}
+
+public sealed class UpdateSalesInvoiceRequest
+{
+    [Required] public int CustomerId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Required, EnumDataType(typeof(SalesInvoiceType))] public SalesInvoiceType InvoiceType { get; set; } = SalesInvoiceType.B2C;
+    [Required, MinLength(1)] public List<CreateSalesInvoiceLineRequest> Lines { get; set; } = new();
+}

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/SalesReportDtos.cs

@@ -0,0 +1,68 @@
+namespace ERPCore.Dtos.Sales;
+
+public sealed record SalesDailySummaryRowDto(
+    DateOnly Date,
+    int InvoiceCount,
+    int SlipCount,
+    decimal InvoiceSubtotal,
+    decimal SlipSubtotal,
+    decimal DiscountTotal,
+    decimal FreeQtyTotal,
+    decimal TaxTotal,
+    decimal GrandTotal);
+
+public sealed record SalesItemSummaryRowDto(
+    int ItemId,
+    string ItemName,
+    decimal SoldQty,
+    decimal FreeQty,
+    decimal GrossAmount,
+    decimal DiscountTotal,
+    decimal TaxTotal,
+    decimal NetAmount);
+
+public sealed record SalesCustomerSummaryRowDto(
+    int CustomerId,
+    string CustomerName,
+    int InvoiceCount,
+    int SlipCount,
+    decimal SoldQty,
+    decimal FreeQty,
+    decimal GrossAmount,
+    decimal DiscountTotal,
+    decimal TaxTotal,
+    decimal NetAmount);
+
+public sealed record SalesWarehouseSummaryRowDto(
+    int WarehouseId,
+    string WarehouseName,
+    int InvoiceCount,
+    int SlipCount,
+    decimal SoldQty,
+    decimal FreeQty,
+    decimal GrossAmount,
+    decimal DiscountTotal,
+    decimal TaxTotal,
+    decimal NetAmount);
+
+public sealed record SalesDiscountSummaryRowDto(
+    string DocumentType,
+    string DocumentNo,
+    DateTime DocumentDate,
+    string CustomerName,
+    decimal Subtotal,
+    decimal DiscountTotal,
+    decimal TaxTotal,
+    decimal NetAmount);
+
+public sealed record SalesFreeIssueSummaryRowDto(
+    string DocumentType,
+    string DocumentNo,
+    DateTime DocumentDate,
+    string CustomerName,
+    int ItemId,
+    string ItemName,
+    decimal FreeQty,
+    decimal FreeValue,
+    int WarehouseId,
+    string WarehouseName);

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

@@ -0,0 +1,79 @@
+using System.ComponentModel.DataAnnotations;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Dtos.Sales;
+
+public sealed record SalesSlipLineDto(
+    int SalesSlipLineId, int ItemId, string Description, decimal Qty, decimal FreeQty, int UomId,
+    int WarehouseId, decimal UnitPrice, decimal BaseCost, string PriceSource, decimal DiscountPct,
+    decimal DiscountAmount, SalesDiscountMode DiscountMode, decimal NetUnitPrice, decimal LineTotal,
+    decimal TaxPct, decimal TaxAmount, bool IsFreeIssue, int? ParentLineId);
+
+public sealed record SalesSlipTotalsDto(
+    decimal Subtotal, decimal DiscountTotal, decimal FreeQtyTotal, decimal TaxTotal, decimal GrandTotal,
+    decimal PaidAmount, decimal BalanceAmount);
+
+public sealed record SalesSlipDto(
+    int SalesSlipId, string SlipNo, DateTime SlipDate, int CustomerId,
+    string CustomerSnapshotName, int WarehouseId, int CashierUserId, SalesSlipStatus Status,
+    DateTime CreatedAt, DateTime? UpdatedAt, SalesSlipTotalsDto Totals, IReadOnlyList<SalesSlipLineDto> Lines);
+
+public sealed record SalesSlipSummaryDto(
+    int SalesSlipId, string SlipNo, DateTime SlipDate, int CustomerId,
+    string CustomerSnapshotName, int WarehouseId, SalesSlipStatus Status,
+    SalesSlipTotalsDto Totals, DateTime CreatedAt);
+
+/// <summary>Quantities are in the item's base UOM — see <c>SalesInvoicePostingIssueDto</c>.</summary>
+public sealed record SalesSlipPostingIssueDto(
+    int SalesSlipLineId, int ItemId, string ItemSku, string ItemName, int WarehouseId,
+    decimal RequestedQty, decimal AvailableQty, decimal ShortQty, bool IsFreeIssue,
+    string BaseUomName = "");
+
+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; }
+    [Required] public int UomId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Range(0.0001, double.MaxValue)] public decimal Qty { get; set; }
+    [Range(0, double.MaxValue)] public decimal FreeQty { get; set; }
+    [Range(0, double.MaxValue)] public decimal? UnitPrice { get; set; }
+    public bool AllowManualPriceOverride { get; set; }
+    [Required, EnumDataType(typeof(SalesDiscountMode))] public SalesDiscountMode DiscountMode { get; set; } = SalesDiscountMode.Percentage;
+    [Range(0, 100)] public decimal DiscountPct { get; set; }
+    [Range(0, double.MaxValue)] public decimal DiscountAmount { get; set; }
+    [Range(0, double.MaxValue)] public decimal DiscountValue { get; set; }
+    [Range(0, 100)] public decimal TaxPct { get; set; }
+    public bool IsFreeIssue { get; set; }
+    public int? ParentLineId { get; set; }
+}
+
+public sealed class CreateSalesSlipRequest
+{
+    [Required] public int CustomerId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Required] public int CashierUserId { get; set; }
+    [Required, MinLength(1)] public List<CreateSalesSlipLineRequest> Lines { get; set; } = new();
+}
+
+public sealed class UpdateSalesSlipRequest
+{
+    [Required] public int CustomerId { get; set; }
+    [Required] public int WarehouseId { get; set; }
+    [Required] public int CashierUserId { get; set; }
+    [Required, MinLength(1)] public List<CreateSalesSlipLineRequest> Lines { get; set; } = new();
+}

Backend/ERPCore/Dtos/Stock/StockDtos.cs

@@ -2,16 +2,23 @@ using ERPCore.Domain.Enums;
 
 namespace ERPCore.Dtos.Stock;
 
+// Every quantity a stock endpoint returns is in the item's base UOM — stock, layers and the
+// ledger are base-only by construction. The BaseUomId/BaseUomName pair on each of these DTOs
+// exists so a client can *label* those figures; without it every stock screen renders a bare
+// number the user has to guess the unit of. They are never a conversion instruction.
+
 /// <summary>Stock enquiry (docs/11 §5.1). available = onHand − onHold − reserved − inTransit(out).</summary>
 public sealed record StockOnHandDto(
     int ItemId, int WarehouseId, decimal OnHand, decimal Available,
-    decimal OnHold, decimal InTransit, decimal Reserved, DateTime AsOf);
+    decimal OnHold, decimal InTransit, decimal Reserved, DateTime AsOf,
+    int BaseUomId = 0, string BaseUomName = "");
 
 /// <summary>A stock-ledger row (docs/11 §5.2).</summary>
 public sealed record StockLedgerRowDto(
     int LedgerId, int ItemId, int WarehouseId, int? BinId, int? BatchId, int? SerialId,
     Direction Direction, decimal QtyBase, decimal UnitCost, decimal Value, decimal RunningBalance,
-    string SourceDocType, int SourceDocId, int UserId, DateTime CreatedAt);
+    string SourceDocType, int SourceDocId, int UserId, DateTime CreatedAt,
+    int BaseUomId = 0, string BaseUomName = "");
 
 /// <summary>An open FIFO layer in a valuation (docs/11 §5.3).</summary>
 public sealed record StockValuationLayerDto(int LayerId, decimal QtyRemaining, decimal UnitCost, decimal Value, DateTime ReceiptDate);
@@ -19,4 +26,5 @@ public sealed record StockValuationLayerDto(int LayerId, decimal QtyRemaining, d
 /// <summary>Valuation of on-hand stock from open FIFO layers (docs/11 §5.3).</summary>
 public sealed record StockValuationDto(
     int ItemId, int WarehouseId, IReadOnlyList<StockValuationLayerDto> Layers,
-    decimal TotalQty, decimal TotalValue, string Currency, string CostingMethod);
+    decimal TotalQty, decimal TotalValue, string Currency, string CostingMethod,
+    int BaseUomId = 0, string BaseUomName = "");

Backend/ERPCore/Dtos/Uoms/UomDtos.cs

@@ -9,3 +9,12 @@ public sealed class CreateUomRequest
 {
     [Required, StringLength(50)] public string Name { get; set; } = string.Empty;
 }
+
+/// <summary>
+/// A UOM an item may actually be transacted in: its base UOM (<paramref name="Factor"/> 1,
+/// <paramref name="IsBase"/> true) plus every UOM it has a conversion from. Backs both
+/// entry-time validation and <c>GET /items/{itemId}/uoms</c>, so the client can offer only
+/// units that will survive posting instead of the whole global list.
+/// </summary>
+/// <param name="Factor">Multiply a quantity in this UOM by <paramref name="Factor"/> to get base UOM.</param>
+public sealed record AllowedUomDto(int UomId, string Name, decimal Factor, bool IsBase);

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

@@ -0,0 +1,46 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class BundleSaleConfiguration : IEntityTypeConfiguration<BundleSale>
+{
+    public void Configure(EntityTypeBuilder<BundleSale> builder)
+    {
+        builder.ToTable("bundle_sales");
+        builder.HasKey(x => x.BundleSaleId);
+        builder.Property(x => x.BundleNo).IsRequired().HasMaxLength(50);
+        builder.HasIndex(x => x.BundleNo).IsUnique();
+        builder.Property(x => x.BundleDate).IsRequired();
+        builder.Property(x => x.CustomerSnapshotName).IsRequired().HasMaxLength(200);
+        builder.Property(x => x.BundleName).IsRequired().HasMaxLength(200);
+        builder.Property(x => x.BundleCode).IsRequired().HasMaxLength(50);
+        builder.Property(x => x.Status)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(BundleSaleStatus.Draft);
+        builder.Property(x => x.ComponentSubtotal).HasPrecision(18, 4);
+        builder.Property(x => x.BundlePrice).HasPrecision(18, 4);
+        builder.Property(x => x.MarginAmount).HasPrecision(18, 4);
+        builder.Property(x => x.DiscountTotal).HasPrecision(18, 4);
+        builder.Property(x => x.TaxTotal).HasPrecision(18, 4);
+        builder.Property(x => x.GrandTotal).HasPrecision(18, 4);
+        builder.Property(x => x.CreatedAt).IsRequired();
+        builder.Property(x => x.ConcurrencyStamp)
+            .IsRequired()
+            .HasColumnType("integer")
+            .HasDefaultValue(0)
+            .IsConcurrencyToken();
+
+        builder.HasOne(x => x.Customer).WithMany().HasForeignKey(x => x.CustomerId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.Warehouse).WithMany().HasForeignKey(x => x.WarehouseId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.CashierUser).WithMany().HasForeignKey(x => x.CashierUserId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.BundleSaleTemplate).WithMany().HasForeignKey(x => x.BundleSaleTemplateId).OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasMany(x => x.Lines)
+            .WithOne(x => x.BundleSale)
+            .HasForeignKey(x => x.BundleSaleId)
+            .OnDelete(DeleteBehavior.Cascade);
+    }
+}

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

@@ -0,0 +1,26 @@
+using ERPCore.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class BundleSaleLineConfiguration : IEntityTypeConfiguration<BundleSaleLine>
+{
+    public void Configure(EntityTypeBuilder<BundleSaleLine> builder)
+    {
+        builder.ToTable("bundle_sale_lines");
+        builder.HasKey(x => x.BundleSaleLineId);
+        builder.Property(x => x.Description).IsRequired().HasMaxLength(200);
+        builder.Property(x => x.Qty).HasPrecision(18, 4);
+        builder.Property(x => x.QtyBase).HasPrecision(18, 4);
+        builder.Property(x => x.ConversionFactor).HasPrecision(18, 6).HasDefaultValue(1m);
+        builder.Property(x => x.UnitPrice).HasPrecision(18, 4);
+        builder.Property(x => x.LineTotal).HasPrecision(18, 4);
+        builder.Property(x => x.IncludeInBundle).HasDefaultValue(true);
+        builder.Property(x => x.IsComponent).HasDefaultValue(true);
+
+        builder.HasOne(x => x.Item).WithMany().HasForeignKey(x => x.ItemId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.Uom).WithMany().HasForeignKey(x => x.UomId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.Warehouse).WithMany().HasForeignKey(x => x.WarehouseId).OnDelete(DeleteBehavior.Restrict);
+    }
+}

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

@@ -0,0 +1,34 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class BundleSaleTemplateConfiguration : IEntityTypeConfiguration<BundleSaleTemplate>
+{
+    public void Configure(EntityTypeBuilder<BundleSaleTemplate> builder)
+    {
+        builder.ToTable("bundle_sale_templates");
+        builder.HasKey(x => x.BundleSaleTemplateId);
+
+        builder.Property(x => x.TemplateCode).IsRequired().HasMaxLength(50);
+        builder.HasIndex(x => x.TemplateCode).IsUnique();
+        builder.Property(x => x.TemplateName).IsRequired().HasMaxLength(200);
+        builder.Property(x => x.Description).HasMaxLength(1000);
+        builder.Property(x => x.Status)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(EntityStatus.Active);
+        builder.Property(x => x.CreatedAt).IsRequired();
+        builder.Property(x => x.ConcurrencyStamp)
+            .IsRequired()
+            .HasColumnType("integer")
+            .HasDefaultValue(0)
+            .IsConcurrencyToken();
+
+        builder.HasMany(x => x.Lines)
+            .WithOne(x => x.BundleSaleTemplate)
+            .HasForeignKey(x => x.BundleSaleTemplateId)
+            .OnDelete(DeleteBehavior.Cascade);
+    }
+}

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

@@ -0,0 +1,21 @@
+using ERPCore.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class BundleSaleTemplateLineConfiguration : IEntityTypeConfiguration<BundleSaleTemplateLine>
+{
+    public void Configure(EntityTypeBuilder<BundleSaleTemplateLine> builder)
+    {
+        builder.ToTable("bundle_sale_template_lines");
+        builder.HasKey(x => x.BundleSaleTemplateLineId);
+        builder.Property(x => x.Qty).HasPrecision(18, 4);
+        builder.Property(x => x.UnitPrice).HasPrecision(18, 4);
+        builder.Property(x => x.SortOrder).HasDefaultValue(0);
+
+        builder.HasOne(x => x.Item).WithMany().HasForeignKey(x => x.ItemId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.Uom).WithMany().HasForeignKey(x => x.UomId).OnDelete(DeleteBehavior.Restrict);
+        builder.HasOne(x => x.Warehouse).WithMany().HasForeignKey(x => x.WarehouseId).OnDelete(DeleteBehavior.Restrict);
+    }
+}

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

@@ -0,0 +1,50 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class CustomerConfiguration : IEntityTypeConfiguration<Customer>
+{
+    public void Configure(EntityTypeBuilder<Customer> builder)
+    {
+        builder.ToTable("customers");
+        builder.HasKey(c => c.CustomerId);
+
+        builder.Property(c => c.CustomerCode).IsRequired().HasMaxLength(50);
+        builder.HasIndex(c => c.CustomerCode).IsUnique();
+
+        builder.Property(c => c.CustomerType)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(CustomerType.B2C);
+
+        builder.Property(c => c.Name).IsRequired().HasMaxLength(200);
+        builder.Property(c => c.DisplayName).HasMaxLength(200);
+        builder.Property(c => c.Phone).HasMaxLength(30);
+        builder.Property(c => c.Email).HasMaxLength(100);
+        builder.Property(c => c.AddressLine1).HasMaxLength(250);
+        builder.Property(c => c.AddressLine2).HasMaxLength(250);
+        builder.Property(c => c.City).HasMaxLength(100);
+        builder.Property(c => c.Country).HasMaxLength(100);
+        builder.Property(c => c.TaxRegistrationNo).HasMaxLength(50);
+
+        builder.Property(c => c.CreditLimit).HasPrecision(18, 4);
+        builder.Property(c => c.CreditDays).IsRequired();
+
+        builder.HasOne(c => c.DefaultWarehouse)
+            .WithMany()
+            .HasForeignKey(c => c.DefaultWarehouseId)
+            .OnDelete(DeleteBehavior.SetNull);
+
+        builder.Property(c => c.Status)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(EntityStatus.Active);
+
+        builder.Property(c => c.CreatedAt).IsRequired();
+        builder.Property(c => c.RowVersion).IsRowVersion();
+
+        builder.HasIndex(c => c.Status);
+        builder.HasIndex(c => c.CustomerType);
+    }
+}

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

@@ -36,6 +36,8 @@ public sealed class GrnLineConfiguration : IEntityTypeConfiguration<GrnLine>
         builder.HasKey(l => l.GrnLineId);
 
         builder.Property(l => l.Qty).HasPrecision(18, 4);
+        builder.Property(l => l.QtyBase).HasPrecision(18, 4);
+        builder.Property(l => l.ConversionFactor).HasPrecision(18, 6).HasDefaultValue(1m);
         builder.Property(l => l.UnitCost).HasPrecision(18, 6);
         builder.Property(l => l.PoUnitPrice).HasPrecision(18, 6);
         builder.Property(l => l.DiscountPct).HasPrecision(9, 4);

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

@@ -38,7 +38,8 @@ public sealed class NavItemConfiguration : IEntityTypeConfiguration<NavItem>
             new NavItem { NavItemId = 9, Code = "settings", Label = "Settings", Href = "/dashboard/settings", SortOrder = 9 },
             new NavItem { NavItemId = 10, Code = "help", Label = "Help", Href = "/dashboard/help", SortOrder = 10 },
             new NavItem { NavItemId = 11, Code = "ledgers", Label = "Ledgers", Href = "/dashboard/ledgers", SortOrder = 11 },
-            new NavItem { NavItemId = 12, Code = "accounts", Label = "Accounts", Href = "/dashboard/accounts", SortOrder = 12 }
+            new NavItem { NavItemId = 12, Code = "accounts", Label = "Accounts", Href = "/dashboard/accounts", SortOrder = 12 },
+            new NavItem { NavItemId = 13, Code = "sales", Label = "Sales", Href = "/dashboard/sales", SortOrder = 13 }
         );
     }
 }

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

@@ -49,6 +49,9 @@ public sealed class PoLineConfiguration : IEntityTypeConfiguration<PoLine>
         builder.HasKey(l => l.PoLineId);
 
         builder.Property(l => l.Qty).HasPrecision(18, 4);
+        builder.Property(l => l.QtyBase).HasPrecision(18, 4);
+        builder.Property(l => l.QtyReceivedBase).HasPrecision(18, 4);
+        builder.Property(l => l.ConversionFactor).HasPrecision(18, 6).HasDefaultValue(1m);
         builder.Property(l => l.UnitPrice).HasPrecision(18, 4);
         builder.Property(l => l.Tax).HasPrecision(9, 4);
         builder.Property(l => l.QtyReceived).HasPrecision(18, 4);

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

@@ -0,0 +1,98 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class SalesInvoiceConfiguration : IEntityTypeConfiguration<SalesInvoice>
+{
+    public void Configure(EntityTypeBuilder<SalesInvoice> builder)
+    {
+        builder.ToTable("sales_invoices");
+        builder.HasKey(x => x.SalesInvoiceId);
+
+        builder.Property(x => x.InvoiceNo).IsRequired().HasMaxLength(50);
+        builder.HasIndex(x => x.InvoiceNo).IsUnique();
+
+        builder.Property(x => x.InvoiceDate).IsRequired();
+
+        builder.HasOne(x => x.Customer)
+            .WithMany()
+            .HasForeignKey(x => x.CustomerId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.CustomerSnapshotName).IsRequired().HasMaxLength(200);
+        builder.Property(x => x.CustomerSnapshotTaxNo).HasMaxLength(50);
+
+        builder.HasOne(x => x.Warehouse)
+            .WithMany()
+            .HasForeignKey(x => x.WarehouseId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.InvoiceType)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(SalesInvoiceType.B2C);
+
+        builder.Property(x => x.Status)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(SalesInvoiceStatus.Draft);
+
+        foreach (var p in new[] { nameof(SalesInvoice.Subtotal), nameof(SalesInvoice.DiscountTotal), nameof(SalesInvoice.TaxTotal), nameof(SalesInvoice.GrandTotal), nameof(SalesInvoice.RoundOff), nameof(SalesInvoice.NetPayable), nameof(SalesInvoice.PaidAmount), nameof(SalesInvoice.BalanceAmount) })
+            builder.Property<decimal>(p).HasPrecision(18, 4);
+
+        builder.Property(x => x.CreatedAt).IsRequired();
+        builder.Property(x => x.RowVersion).IsRowVersion();
+
+        builder.HasIndex(x => x.Status);
+        builder.HasIndex(x => x.InvoiceDate);
+
+        builder.HasMany(x => x.Lines)
+            .WithOne(x => x.SalesInvoice)
+            .HasForeignKey(x => x.SalesInvoiceId)
+            .OnDelete(DeleteBehavior.Cascade);
+    }
+}
+
+public sealed class SalesInvoiceLineConfiguration : IEntityTypeConfiguration<SalesInvoiceLine>
+{
+    public void Configure(EntityTypeBuilder<SalesInvoiceLine> builder)
+    {
+        builder.ToTable("sales_invoice_lines");
+        builder.HasKey(x => x.SalesInvoiceLineId);
+
+        builder.HasOne(x => x.Item)
+            .WithMany()
+            .HasForeignKey(x => x.ItemId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.Description).IsRequired().HasMaxLength(200);
+
+        builder.Property(x => x.Qty).HasPrecision(18, 4);
+        builder.Property(x => x.FreeQty).HasPrecision(18, 4);
+        builder.Property(x => x.QtyBase).HasPrecision(18, 4);
+        builder.Property(x => x.FreeQtyBase).HasPrecision(18, 4);
+        builder.Property(x => x.ConversionFactor).HasPrecision(18, 6).HasDefaultValue(1m);
+        builder.Property(x => x.UnitPrice).HasPrecision(18, 4);
+        builder.Property(x => x.BaseCost).HasPrecision(18, 4);
+        builder.Property(x => x.DiscountPct).HasPrecision(9, 4);
+        builder.Property(x => x.DiscountAmount).HasPrecision(18, 4);
+        builder.Property(x => x.NetUnitPrice).HasPrecision(18, 4);
+        builder.Property(x => x.LineTotal).HasPrecision(18, 4);
+        builder.Property(x => x.TaxPct).HasPrecision(9, 4);
+        builder.Property(x => x.TaxAmount).HasPrecision(18, 4);
+
+        builder.HasOne(x => x.Uom)
+            .WithMany()
+            .HasForeignKey(x => x.UomId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasOne(x => x.Warehouse)
+            .WithMany()
+            .HasForeignKey(x => x.WarehouseId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.PriceSource).HasMaxLength(50);
+        builder.Property(x => x.RowVersion).IsRowVersion();
+    }
+}

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

@@ -0,0 +1,98 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace ERPCore.Infra.Persistence.Configurations;
+
+public sealed class SalesSlipConfiguration : IEntityTypeConfiguration<SalesSlip>
+{
+    public void Configure(EntityTypeBuilder<SalesSlip> builder)
+    {
+        builder.ToTable("sales_slips");
+        builder.HasKey(x => x.SalesSlipId);
+
+        builder.Property(x => x.SlipNo).IsRequired().HasMaxLength(50);
+        builder.HasIndex(x => x.SlipNo).IsUnique();
+
+        builder.Property(x => x.SlipDate).IsRequired();
+
+        builder.HasOne(x => x.Customer)
+            .WithMany()
+            .HasForeignKey(x => x.CustomerId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.CustomerSnapshotName).IsRequired().HasMaxLength(200);
+
+        builder.HasOne(x => x.Warehouse)
+            .WithMany()
+            .HasForeignKey(x => x.WarehouseId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasOne(x => x.CashierUser)
+            .WithMany()
+            .HasForeignKey(x => x.CashierUserId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.Status)
+            .HasConversion<string>().HasMaxLength(20).IsRequired()
+            .HasDefaultValue(SalesSlipStatus.Draft);
+
+        foreach (var p in new[] { nameof(SalesSlip.Subtotal), nameof(SalesSlip.DiscountTotal), nameof(SalesSlip.TaxTotal), nameof(SalesSlip.GrandTotal), nameof(SalesSlip.PaidAmount), nameof(SalesSlip.BalanceAmount) })
+            builder.Property<decimal>(p).HasPrecision(18, 4);
+
+        builder.Property(x => x.CreatedAt).IsRequired();
+        builder.Property(x => x.RowVersion).IsRowVersion();
+
+        builder.HasIndex(x => x.Status);
+        builder.HasIndex(x => x.SlipDate);
+
+        builder.HasMany(x => x.Lines)
+            .WithOne(x => x.SalesSlip)
+            .HasForeignKey(x => x.SalesSlipId)
+            .OnDelete(DeleteBehavior.Cascade);
+    }
+}
+
+public sealed class SalesSlipLineConfiguration : IEntityTypeConfiguration<SalesSlipLine>
+{
+    public void Configure(EntityTypeBuilder<SalesSlipLine> builder)
+    {
+        builder.ToTable("sales_slip_lines");
+        builder.HasKey(x => x.SalesSlipLineId);
+
+        builder.HasOne(x => x.Item)
+            .WithMany()
+            .HasForeignKey(x => x.ItemId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.Description).IsRequired().HasMaxLength(200);
+
+        builder.Property(x => x.Qty).HasPrecision(18, 4);
+        builder.Property(x => x.FreeQty).HasPrecision(18, 4);
+        builder.Property(x => x.QtyBase).HasPrecision(18, 4);
+        builder.Property(x => x.FreeQtyBase).HasPrecision(18, 4);
+        builder.Property(x => x.ConversionFactor).HasPrecision(18, 6).HasDefaultValue(1m);
+        builder.Property(x => x.UnitPrice).HasPrecision(18, 4);
+        builder.Property(x => x.BaseCost).HasPrecision(18, 4);
+        builder.Property(x => x.DiscountPct).HasPrecision(9, 4);
+        builder.Property(x => x.DiscountAmount).HasPrecision(18, 4);
+        builder.Property(x => x.NetUnitPrice).HasPrecision(18, 4);
+        builder.Property(x => x.LineTotal).HasPrecision(18, 4);
+        builder.Property(x => x.TaxPct).HasPrecision(9, 4);
+        builder.Property(x => x.TaxAmount).HasPrecision(18, 4);
+
+        builder.HasOne(x => x.Uom)
+            .WithMany()
+            .HasForeignKey(x => x.UomId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.HasOne(x => x.Warehouse)
+            .WithMany()
+            .HasForeignKey(x => x.WarehouseId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        builder.Property(x => x.PriceSource).HasMaxLength(50);
+        builder.Property(x => x.RowVersion).IsRowVersion();
+    }
+}

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

@@ -33,6 +33,7 @@ public sealed class SubNavItemConfiguration : IEntityTypeConfiguration<SubNavIte
             new SubNavItem { SubNavItemId = 6, NavItemId = 2, Code = "products.configuration", Label = "Configuration", Href = "/dashboard/products/settings", SortOrder = 6 },
             new SubNavItem { SubNavItemId = 7, NavItemId = 9, Code = "settings.roles", Label = "Roles", Href = "/dashboard/settings/roles", SortOrder = 1 },
             new SubNavItem { SubNavItemId = 8, NavItemId = 9, Code = "settings.users", Label = "Users", Href = "/dashboard/settings/users", SortOrder = 2 },
+            new SubNavItem { SubNavItemId = 23, NavItemId = 13, Code = "sales.bundle-sales", Label = "Bundle Sales", Href = "/dashboard/sales/bundles", SortOrder = 1 },
             // Procurement (NavItemId 4) children — mirror the hub page order.
             // IDs 17-20 (not 9-12): 9-12 were already claimed by the Ledgers sub-items below;
             // these procurement rows were never actually migrated into the database before now.

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

@@ -30,5 +30,9 @@ public sealed class UomConversionConfiguration : IEntityTypeConfiguration<UomCon
 
         // One conversion per (item, from, to) triple.
         builder.HasIndex(c => new { c.ItemId, c.FromUomId, c.ToUomId }).IsUnique();
+
+        // The API guards this too, but UomConverter divides unit cost by the factor — a zero
+        // reaching the table from a seeder or direct SQL would be a divide-by-zero at post time.
+        builder.ToTable(t => t.HasCheckConstraint("ck_uom_conversions_factor_positive", "\"Factor\" > 0"));
     }
 }

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 +104,754 @@ 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);
+
+        try
+        {
+            dirty |= await SeedBundleSalesAsync(db, ct);
+        }
+        catch
+        {
+            // Bundle demo data is best-effort only; never block startup because of seed drift.
+        }
+
+        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 || s.DocType == DocumentTypes.BundleSale))
+            .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 },
+            new NumberSequence { DocType = DocumentTypes.BundleSale, 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> SeedBundleSalesAsync(ErpDbContext db, CancellationToken ct)
+    {
+        if (await db.BundleSaleTemplates.AnyAsync(ct) || await db.BundleSales.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 now = DateTime.UtcNow;
+        var template = new BundleSaleTemplate
+        {
+            TemplateCode = "BND-DEMO-001",
+            TemplateName = "Demo Bundle Pack",
+            Description = "Seeded fixed bundle template for integration testing",
+            Status = EntityStatus.Active,
+            CreatedAt = now,
+            Lines =
+            [
+                new BundleSaleTemplateLine
+                {
+                    ItemId = items[0].ItemId,
+                    UomId = uom.UomId,
+                    WarehouseId = warehouse.WarehouseId,
+                    Qty = 1m,
+                    UnitPrice = items[0].SalePrice.GetValueOrDefault(),
+                    IncludeInBundle = true,
+                    SortOrder = 1
+                },
+                new BundleSaleTemplateLine
+                {
+                    ItemId = items[1].ItemId,
+                    UomId = uom.UomId,
+                    WarehouseId = warehouse.WarehouseId,
+                    Qty = 1m,
+                    UnitPrice = items[1].SalePrice.GetValueOrDefault(),
+                    IncludeInBundle = true,
+                    SortOrder = 2
+                }
+            ]
+        };
+
+        db.BundleSaleTemplates.Add(template);
+        await db.SaveChangesAsync(ct);
+
+        var bundleSales = new[]
+        {
+            new BundleSale
+            {
+                BundleNo = $"BND-{now:yyyy}-00001",
+                BundleDate = now.Date.AddDays(-2),
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.DisplayName ?? customer.Name,
+                WarehouseId = warehouse.WarehouseId,
+                CashierUserId = user.UserId,
+                BundleSaleTemplateId = template.BundleSaleTemplateId,
+                BundleName = "Demo Bundle Draft",
+                BundleCode = "BND-DEMO-001",
+                Status = BundleSaleStatus.Draft,
+                ComponentSubtotal = items[0].SalePrice.GetValueOrDefault() + items[1].SalePrice.GetValueOrDefault(),
+                BundlePrice = 0m,
+                MarginAmount = -(items[0].SalePrice.GetValueOrDefault() + items[1].SalePrice.GetValueOrDefault()),
+                DiscountTotal = items[0].SalePrice.GetValueOrDefault() + items[1].SalePrice.GetValueOrDefault(),
+                TaxTotal = 0m,
+                GrandTotal = 0m,
+                CreatedAt = now.AddDays(-2),
+                Lines =
+                [
+                    new BundleSaleLine
+                    {
+                        ItemId = items[0].ItemId,
+                        Description = items[0].Name,
+                        Qty = 1m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = items[0].SalePrice.GetValueOrDefault(),
+                        LineTotal = items[0].SalePrice.GetValueOrDefault(),
+                        IncludeInBundle = true,
+                        IsComponent = true
+                    },
+                    new BundleSaleLine
+                    {
+                        ItemId = items[1].ItemId,
+                        Description = items[1].Name,
+                        Qty = 1m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = items[1].SalePrice.GetValueOrDefault(),
+                        LineTotal = items[1].SalePrice.GetValueOrDefault(),
+                        IncludeInBundle = true,
+                        IsComponent = true
+                    }
+                ]
+            },
+            new BundleSale
+            {
+                BundleNo = $"BND-{now:yyyy}-00002",
+                BundleDate = now.Date.AddDays(-1),
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.DisplayName ?? customer.Name,
+                WarehouseId = warehouse.WarehouseId,
+                CashierUserId = user.UserId,
+                BundleSaleTemplateId = template.BundleSaleTemplateId,
+                BundleName = "Demo Bundle Posted",
+                BundleCode = "BND-DEMO-001",
+                Status = BundleSaleStatus.Posted,
+                ComponentSubtotal = items[0].SalePrice.GetValueOrDefault() + items[1].SalePrice.GetValueOrDefault(),
+                BundlePrice = (items[0].SalePrice.GetValueOrDefault() + items[1].SalePrice.GetValueOrDefault()) - 10m,
+                MarginAmount = -10m,
+                DiscountTotal = 10m,
+                TaxTotal = 0m,
+                GrandTotal = (items[0].SalePrice.GetValueOrDefault() + items[1].SalePrice.GetValueOrDefault()) - 10m,
+                CreatedAt = now.AddDays(-1),
+                UpdatedAt = now.AddHours(-2),
+                Lines =
+                [
+                    new BundleSaleLine
+                    {
+                        ItemId = items[0].ItemId,
+                        Description = items[0].Name,
+                        Qty = 1m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = items[0].SalePrice.GetValueOrDefault(),
+                        LineTotal = items[0].SalePrice.GetValueOrDefault(),
+                        IncludeInBundle = true,
+                        IsComponent = true
+                    },
+                    new BundleSaleLine
+                    {
+                        ItemId = items[1].ItemId,
+                        Description = items[1].Name,
+                        Qty = 1m,
+                        UomId = uom.UomId,
+                        WarehouseId = warehouse.WarehouseId,
+                        UnitPrice = items[1].SalePrice.GetValueOrDefault(),
+                        LineTotal = items[1].SalePrice.GetValueOrDefault(),
+                        IncludeInBundle = true,
+                        IsComponent = true
+                    }
+                ]
+            },
+            new BundleSale
+            {
+                BundleNo = $"BND-{now:yyyy}-00003",
+                BundleDate = now.Date,
+                CustomerId = customer.CustomerId,
+                CustomerSnapshotName = customer.DisplayName ?? customer.Name,
+                WarehouseId = secondaryWarehouse.WarehouseId,
+                CashierUserId = user.UserId,
+                BundleSaleTemplateId = template.BundleSaleTemplateId,
+                BundleName = "Demo Bundle Cancelled",
+                BundleCode = "BND-DEMO-001",
+                Status = BundleSaleStatus.Cancelled,
+                ComponentSubtotal = items[0].SalePrice.GetValueOrDefault(),
+                BundlePrice = items[0].SalePrice.GetValueOrDefault(),
+                MarginAmount = 0m,
+                DiscountTotal = 0m,
+                TaxTotal = 0m,
+                GrandTotal = items[0].SalePrice.GetValueOrDefault(),
+                CreatedAt = now,
+                UpdatedAt = now,
+                Lines =
+                [
+                    new BundleSaleLine
+                    {
+                        ItemId = items[0].ItemId,
+                        Description = items[0].Name,
+                        Qty = 1m,
+                        UomId = uom.UomId,
+                        WarehouseId = secondaryWarehouse.WarehouseId,
+                        UnitPrice = items[0].SalePrice.GetValueOrDefault(),
+                        LineTotal = items[0].SalePrice.GetValueOrDefault(),
+                        IncludeInBundle = true,
+                        IsComponent = true
+                    }
+                ]
+            }
+        };
+
+        db.BundleSales.AddRange(bundleSales);
+        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)
     {
@@ -22,6 +23,7 @@ public class ErpDbContext : DbContext
     }
 
     // --- Master Data (docs/10 Part C.1) ---
+    public DbSet<Customer> Customers => Set<Customer>();
     public DbSet<Category> Categories => Set<Category>();
     public DbSet<SubCategory> SubCategories => Set<SubCategory>();
     public DbSet<Brand> Brands => Set<Brand>();
@@ -34,6 +36,7 @@ public class ErpDbContext : DbContext
     public DbSet<Vendor> Vendors => Set<Vendor>();
     public DbSet<Warehouse> Warehouses => Set<Warehouse>();
     public DbSet<Bin> Bins => Set<Bin>();
+    
     /// <summary>Singleton row (FR-MD-11).</summary>
     public DbSet<ProductConfig> ProductConfig => Set<ProductConfig>();
 
@@ -82,6 +85,16 @@ public class ErpDbContext : DbContext
     public DbSet<PurchaseReturn> PurchaseReturns => Set<PurchaseReturn>();
     public DbSet<PurchaseReturnLine> PurchaseReturnLines => Set<PurchaseReturnLine>();
 
+    // --- Sales (Phase 1) ---
+    public DbSet<SalesInvoice> SalesInvoices => Set<SalesInvoice>();
+    public DbSet<SalesInvoiceLine> SalesInvoiceLines => Set<SalesInvoiceLine>();
+    public DbSet<SalesSlip> SalesSlips => Set<SalesSlip>();
+    public DbSet<SalesSlipLine> SalesSlipLines => Set<SalesSlipLine>();
+    public DbSet<BundleSaleTemplate> BundleSaleTemplates => Set<BundleSaleTemplate>();
+    public DbSet<BundleSaleTemplateLine> BundleSaleTemplateLines => Set<BundleSaleTemplateLine>();
+    public DbSet<BundleSale> BundleSales => Set<BundleSale>();
+    public DbSet<BundleSaleLine> BundleSaleLines => Set<BundleSaleLine>();
+
     // --- Reference data (docs/10 Part C.7) ---
     public DbSet<ReasonCode> ReasonCodes => Set<ReasonCode>();
 
@@ -178,24 +191,44 @@ 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/Infra/Persistence/Migrations/20260716134938_AddBrandsSubcategoriesItemTypesAndProductConfig.cs

@@ -1,442 +0,0 @@
-using System;
-using Microsoft.EntityFrameworkCore.Migrations;
-using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
-
-#nullable disable
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <summary>
-    /// Adds the Brand / SubCategory / ItemType masters and the singleton product config,
-    /// and converts CATEGORY from a self-nesting tree into a fixed two-level
-    /// Category → SubCategory hierarchy (docs/10 Part C.1).
-    /// <para>
-    /// <b>This migration carries data, not just DDL.</b> The scaffolded version dropped
-    /// <c>categories.ParentId</c> outright, which would have silently flattened every
-    /// child category into a root and left items pointing at what is now a top-level
-    /// category — losing the parent entirely. The hand-written steps below (marked
-    /// "data migration") move child categories into <c>subcategories</c> and repoint items
-    /// onto the correct (category, subcategory) pair before the column goes away.
-    /// </para>
-    /// </summary>
-    public partial class AddBrandsSubcategoriesItemTypesAndProductConfig : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-            // NOTE: the ParentId drop is deliberately deferred to the bottom of this method —
-            // the data migration reads it. Order here is load-bearing.
-            migrationBuilder.RenameColumn(
-                name: "ItemType",
-                table: "items",
-                newName: "StockNature");
-
-            migrationBuilder.AddColumn<int>(
-                name: "BrandId",
-                table: "items",
-                type: "integer",
-                nullable: true);
-
-            migrationBuilder.AddColumn<int>(
-                name: "SubCategoryId",
-                table: "items",
-                type: "integer",
-                nullable: true);
-
-            migrationBuilder.AddColumn<DateTime>(
-                name: "CreatedAt",
-                table: "categories",
-                type: "timestamp with time zone",
-                nullable: false,
-                defaultValue: new DateTime(1, 1, 1, 0, 0, 0, 0, DateTimeKind.Unspecified));
-
-            migrationBuilder.AddColumn<string>(
-                name: "Status",
-                table: "categories",
-                type: "character varying(20)",
-                maxLength: 20,
-                nullable: false,
-                defaultValue: "Active");
-
-            migrationBuilder.AddColumn<DateTime>(
-                name: "UpdatedAt",
-                table: "categories",
-                type: "timestamp with time zone",
-                nullable: true);
-
-            migrationBuilder.AddColumn<uint>(
-                name: "xmin",
-                table: "categories",
-                type: "xid",
-                rowVersion: true,
-                nullable: false,
-                defaultValue: 0u);
-
-            migrationBuilder.CreateTable(
-                name: "brands",
-                columns: table => new
-                {
-                    BrandId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    Name = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false),
-                    Status = table.Column<string>(type: "character varying(20)", maxLength: 20, nullable: false, defaultValue: "Active"),
-                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
-                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
-                    xmin = table.Column<uint>(type: "xid", rowVersion: true, nullable: false)
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_brands", x => x.BrandId);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "item_types",
-                columns: table => new
-                {
-                    ItemTypeId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    Name = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false),
-                    Status = table.Column<string>(type: "character varying(20)", maxLength: 20, nullable: false, defaultValue: "Active"),
-                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
-                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
-                    xmin = table.Column<uint>(type: "xid", rowVersion: true, nullable: false)
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_item_types", x => x.ItemTypeId);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "product_config",
-                columns: table => new
-                {
-                    ConfigId = table.Column<int>(type: "integer", nullable: false),
-                    SubcategoriesEnabled = table.Column<bool>(type: "boolean", nullable: false, defaultValue: true),
-                    BrandsEnabled = table.Column<bool>(type: "boolean", nullable: false, defaultValue: true),
-                    ItemTypesEnabled = table.Column<bool>(type: "boolean", nullable: false, defaultValue: 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_product_config", x => x.ConfigId);
-                    table.CheckConstraint("ck_product_config_singleton", "\"ConfigId\" = 1");
-                    table.ForeignKey(
-                        name: "FK_product_config_users_UpdatedBy",
-                        column: x => x.UpdatedBy,
-                        principalTable: "users",
-                        principalColumn: "UserId",
-                        onDelete: ReferentialAction.Restrict);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "subcategories",
-                columns: table => new
-                {
-                    SubCategoryId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    Name = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false),
-                    CategoryId = table.Column<int>(type: "integer", nullable: false),
-                    Status = table.Column<string>(type: "character varying(20)", maxLength: 20, nullable: false, defaultValue: "Active"),
-                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
-                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
-                    xmin = table.Column<uint>(type: "xid", rowVersion: true, nullable: false)
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_subcategories", x => x.SubCategoryId);
-                    table.ForeignKey(
-                        name: "FK_subcategories_categories_CategoryId",
-                        column: x => x.CategoryId,
-                        principalTable: "categories",
-                        principalColumn: "CategoryId",
-                        onDelete: ReferentialAction.Restrict);
-                });
-
-            // ---------------------------------------------------------------------------
-            // DATA MIGRATION — must run before ParentId is dropped.
-            // ---------------------------------------------------------------------------
-
-            // Existing categories predate CreatedAt; the added column defaulted them to
-            // 0001-01-01. Stamp them with the migration time instead of a sentinel date.
-            migrationBuilder.Sql(@"
-                UPDATE categories SET ""CreatedAt"" = NOW() AT TIME ZONE 'utc';
-            ");
-
-            // Carry the old category id alongside each new subcategory so items can be
-            // repointed by join below. Dropped again once the repoint is done.
-            migrationBuilder.Sql(@"
-                ALTER TABLE subcategories ADD COLUMN legacy_category_id integer;
-            ");
-
-            // Walk the old tree to its roots. The previous model allowed unlimited nesting,
-            // but the new one is exactly two levels — so a category at any depth below the
-            // root collapses into a subcategory of its ROOT ancestor (a grandchild cannot
-            // become a subcategory of its immediate parent, since that parent is itself
-            // ceasing to be a category).
-            migrationBuilder.Sql(@"
-                WITH RECURSIVE tree AS (
-                    SELECT ""CategoryId"", ""ParentId"", ""Name"", ""CategoryId"" AS root_id
-                    FROM categories
-                    WHERE ""ParentId"" IS NULL
-                    UNION ALL
-                    SELECT c.""CategoryId"", c.""ParentId"", c.""Name"", t.root_id
-                    FROM categories c
-                    JOIN tree t ON c.""ParentId"" = t.""CategoryId""
-                )
-                INSERT INTO subcategories (""Name"", ""CategoryId"", ""Status"", ""CreatedAt"", legacy_category_id)
-                SELECT t.""Name"", t.root_id, 'Active', NOW() AT TIME ZONE 'utc', t.""CategoryId""
-                FROM tree t
-                WHERE t.""ParentId"" IS NOT NULL;
-            ");
-
-            // Repoint items: an item that pointed at a child category now carries the root
-            // category plus the subcategory it actually meant.
-            migrationBuilder.Sql(@"
-                UPDATE items i
-                SET ""SubCategoryId"" = s.""SubCategoryId"",
-                    ""CategoryId""    = s.""CategoryId""
-                FROM subcategories s
-                WHERE s.legacy_category_id = i.""CategoryId"";
-            ");
-
-            // The self-FK must go before the delete, or RESTRICT rejects removing a parent
-            // whose own child row is still present.
-            migrationBuilder.DropForeignKey(
-                name: "FK_categories_categories_ParentId",
-                table: "categories");
-
-            // Every non-root category now lives in `subcategories`, and no item references
-            // one any more (repointed above), so the rows can go.
-            migrationBuilder.Sql(@"
-                DELETE FROM categories WHERE ""ParentId"" IS NOT NULL;
-                ALTER TABLE subcategories DROP COLUMN legacy_category_id;
-            ");
-
-            migrationBuilder.DropIndex(
-                name: "IX_categories_ParentId",
-                table: "categories");
-
-            migrationBuilder.DropColumn(
-                name: "ParentId",
-                table: "categories");
-
-            // Seed the singleton config (FR-MD-11) — all features on. Item writes read this
-            // row, so it must exist before the app serves a single request.
-            migrationBuilder.Sql(@"
-                INSERT INTO product_config (""ConfigId"", ""SubcategoriesEnabled"", ""BrandsEnabled"", ""ItemTypesEnabled"")
-                VALUES (1, TRUE, TRUE, TRUE)
-                ON CONFLICT (""ConfigId"") DO NOTHING;
-            ");
-
-            // ---------------------------------------------------------------------------
-
-            migrationBuilder.CreateIndex(
-                name: "IX_items_BrandId",
-                table: "items",
-                column: "BrandId");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_items_SubCategoryId",
-                table: "items",
-                column: "SubCategoryId");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_categories_Name",
-                table: "categories",
-                column: "Name",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_categories_Status",
-                table: "categories",
-                column: "Status");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_brands_Name",
-                table: "brands",
-                column: "Name",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_brands_Status",
-                table: "brands",
-                column: "Status");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_item_types_Name",
-                table: "item_types",
-                column: "Name",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_item_types_Status",
-                table: "item_types",
-                column: "Status");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_product_config_UpdatedBy",
-                table: "product_config",
-                column: "UpdatedBy");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_subcategories_CategoryId_Name",
-                table: "subcategories",
-                columns: new[] { "CategoryId", "Name" },
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_subcategories_Status",
-                table: "subcategories",
-                column: "Status");
-
-            migrationBuilder.AddForeignKey(
-                name: "FK_items_brands_BrandId",
-                table: "items",
-                column: "BrandId",
-                principalTable: "brands",
-                principalColumn: "BrandId",
-                onDelete: ReferentialAction.Restrict);
-
-            migrationBuilder.AddForeignKey(
-                name: "FK_items_subcategories_SubCategoryId",
-                table: "items",
-                column: "SubCategoryId",
-                principalTable: "subcategories",
-                principalColumn: "SubCategoryId",
-                onDelete: ReferentialAction.Restrict);
-        }
-
-        /// <summary>
-        /// Reverses the schema change and puts the subcategory data back where it came from.
-        /// <para>
-        /// The scaffolded version simply dropped <c>subcategories</c>, which would have
-        /// discarded exactly what <see cref="Up"/> preserved. Instead each subcategory is
-        /// restored as a child category and its items are repointed back onto it. This is
-        /// not perfectly lossless: the old tree's depth is gone (a former grandchild comes
-        /// back as a direct child of its root), and Brand data cannot survive a schema that
-        /// has nowhere to put it.
-        /// </para>
-        /// </summary>
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.DropForeignKey(
-                name: "FK_items_brands_BrandId",
-                table: "items");
-
-            migrationBuilder.DropForeignKey(
-                name: "FK_items_subcategories_SubCategoryId",
-                table: "items");
-
-            // Restore the parent column + self-FK first so subcategories have somewhere to
-            // land, then move them back before the table is dropped.
-            migrationBuilder.AddColumn<int>(
-                name: "ParentId",
-                table: "categories",
-                type: "integer",
-                nullable: true);
-
-            // ---------------------------------------------------------------------------
-            // DATA MIGRATION (reverse) — must run before `subcategories` is dropped.
-            // ---------------------------------------------------------------------------
-
-            migrationBuilder.Sql(@"
-                ALTER TABLE categories ADD COLUMN legacy_subcategory_id integer;
-            ");
-
-            // Each subcategory becomes a child category again under the same parent.
-            migrationBuilder.Sql(@"
-                INSERT INTO categories (""Name"", ""ParentId"", ""CreatedAt"", ""Status"", legacy_subcategory_id)
-                SELECT s.""Name"", s.""CategoryId"", s.""CreatedAt"", s.""Status"", s.""SubCategoryId""
-                FROM subcategories s;
-            ");
-
-            // Items that carried a subcategory point back at the restored child category.
-            migrationBuilder.Sql(@"
-                UPDATE items i
-                SET ""CategoryId"" = c.""CategoryId""
-                FROM categories c
-                WHERE c.legacy_subcategory_id = i.""SubCategoryId"";
-            ");
-
-            migrationBuilder.Sql(@"
-                ALTER TABLE categories DROP COLUMN legacy_subcategory_id;
-            ");
-
-            // ---------------------------------------------------------------------------
-
-            migrationBuilder.DropTable(
-                name: "brands");
-
-            migrationBuilder.DropTable(
-                name: "item_types");
-
-            migrationBuilder.DropTable(
-                name: "product_config");
-
-            migrationBuilder.DropTable(
-                name: "subcategories");
-
-            migrationBuilder.DropIndex(
-                name: "IX_items_BrandId",
-                table: "items");
-
-            migrationBuilder.DropIndex(
-                name: "IX_items_SubCategoryId",
-                table: "items");
-
-            migrationBuilder.DropIndex(
-                name: "IX_categories_Name",
-                table: "categories");
-
-            migrationBuilder.DropIndex(
-                name: "IX_categories_Status",
-                table: "categories");
-
-            migrationBuilder.DropColumn(
-                name: "BrandId",
-                table: "items");
-
-            migrationBuilder.DropColumn(
-                name: "SubCategoryId",
-                table: "items");
-
-            migrationBuilder.DropColumn(
-                name: "CreatedAt",
-                table: "categories");
-
-            migrationBuilder.DropColumn(
-                name: "Status",
-                table: "categories");
-
-            migrationBuilder.DropColumn(
-                name: "UpdatedAt",
-                table: "categories");
-
-            migrationBuilder.DropColumn(
-                name: "xmin",
-                table: "categories");
-
-            migrationBuilder.RenameColumn(
-                name: "StockNature",
-                table: "items",
-                newName: "ItemType");
-
-            // ParentId itself was re-added at the top of this method, ahead of the reverse
-            // data migration that populates it.
-            migrationBuilder.CreateIndex(
-                name: "IX_categories_ParentId",
-                table: "categories",
-                column: "ParentId");
-
-            migrationBuilder.AddForeignKey(
-                name: "FK_categories_categories_ParentId",
-                table: "categories",
-                column: "ParentId",
-                principalTable: "categories",
-                principalColumn: "CategoryId",
-                onDelete: ReferentialAction.Restrict);
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260718081219_ini2.cs

@@ -1,22 +0,0 @@
-using Microsoft.EntityFrameworkCore.Migrations;
-
-#nullable disable
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <inheritdoc />
-    public partial class ini2 : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-
-        }
-
-        /// <inheritdoc />
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260718092655_AddRolesNavPermissions.cs

@@ -1,303 +0,0 @@
-using System;
-using Microsoft.EntityFrameworkCore.Migrations;
-using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
-
-#nullable disable
-
-#pragma warning disable CA1814 // Prefer jagged arrays over multidimensional
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <inheritdoc />
-    public partial class AddRolesNavPermissions : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.AddColumn<int>(
-                name: "RoleId",
-                table: "users",
-                type: "integer",
-                nullable: true);
-
-            migrationBuilder.CreateTable(
-                name: "nav_items",
-                columns: table => new
-                {
-                    NavItemId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    Code = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: false),
-                    Label = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: false),
-                    Icon = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: true),
-                    Href = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
-                    SortOrder = table.Column<int>(type: "integer", nullable: false),
-                    Status = table.Column<string>(type: "character varying(20)", maxLength: 20, nullable: false, defaultValue: "Active")
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_nav_items", x => x.NavItemId);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "roles",
-                columns: table => new
-                {
-                    RoleId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    auth_role_id = table.Column<Guid>(type: "uuid", nullable: false),
-                    Code = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: false),
-                    Name = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false),
-                    IsSystemRole = table.Column<bool>(type: "boolean", nullable: false, defaultValue: false),
-                    Status = table.Column<string>(type: "character varying(20)", maxLength: 20, nullable: false, defaultValue: "Active"),
-                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
-                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
-                    xmin = table.Column<uint>(type: "xid", rowVersion: true, nullable: false)
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_roles", x => x.RoleId);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "sub_nav_items",
-                columns: table => new
-                {
-                    SubNavItemId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    NavItemId = table.Column<int>(type: "integer", nullable: false),
-                    Code = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: false),
-                    Label = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: false),
-                    Icon = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: true),
-                    Href = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
-                    SortOrder = table.Column<int>(type: "integer", nullable: false),
-                    Status = table.Column<string>(type: "character varying(20)", maxLength: 20, nullable: false, defaultValue: "Active")
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_sub_nav_items", x => x.SubNavItemId);
-                    table.ForeignKey(
-                        name: "FK_sub_nav_items_nav_items_NavItemId",
-                        column: x => x.NavItemId,
-                        principalTable: "nav_items",
-                        principalColumn: "NavItemId",
-                        onDelete: ReferentialAction.Cascade);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "permissions",
-                columns: table => new
-                {
-                    PermissionId = table.Column<int>(type: "integer", nullable: false)
-                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
-                    Code = table.Column<string>(type: "character varying(80)", maxLength: 80, nullable: false),
-                    NavItemId = table.Column<int>(type: "integer", nullable: true),
-                    SubNavItemId = table.Column<int>(type: "integer", nullable: true)
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_permissions", x => x.PermissionId);
-                    table.ForeignKey(
-                        name: "FK_permissions_nav_items_NavItemId",
-                        column: x => x.NavItemId,
-                        principalTable: "nav_items",
-                        principalColumn: "NavItemId",
-                        onDelete: ReferentialAction.Cascade);
-                    table.ForeignKey(
-                        name: "FK_permissions_sub_nav_items_SubNavItemId",
-                        column: x => x.SubNavItemId,
-                        principalTable: "sub_nav_items",
-                        principalColumn: "SubNavItemId",
-                        onDelete: ReferentialAction.Cascade);
-                });
-
-            migrationBuilder.CreateTable(
-                name: "role_permissions",
-                columns: table => new
-                {
-                    RoleId = table.Column<int>(type: "integer", nullable: false),
-                    PermissionId = table.Column<int>(type: "integer", nullable: false)
-                },
-                constraints: table =>
-                {
-                    table.PrimaryKey("PK_role_permissions", x => new { x.RoleId, x.PermissionId });
-                    table.ForeignKey(
-                        name: "FK_role_permissions_permissions_PermissionId",
-                        column: x => x.PermissionId,
-                        principalTable: "permissions",
-                        principalColumn: "PermissionId",
-                        onDelete: ReferentialAction.Cascade);
-                    table.ForeignKey(
-                        name: "FK_role_permissions_roles_RoleId",
-                        column: x => x.RoleId,
-                        principalTable: "roles",
-                        principalColumn: "RoleId",
-                        onDelete: ReferentialAction.Cascade);
-                });
-
-            migrationBuilder.InsertData(
-                table: "nav_items",
-                columns: new[] { "NavItemId", "Code", "Href", "Icon", "Label", "SortOrder" },
-                values: new object[,]
-                {
-                    { 1, "dashboard", "/dashboard", null, "Dashboard", 1 },
-                    { 2, "products", "/dashboard/products", null, "Products", 2 },
-                    { 3, "vendors", "/dashboard/vendors", null, "Vendors", 3 },
-                    { 4, "procurement", "/dashboard/procurement", null, "Procurement", 4 },
-                    { 5, "receiving", "/dashboard/receiving/grn", null, "Receiving", 5 },
-                    { 6, "stock", "/dashboard/stock", null, "Stock", 6 },
-                    { 7, "warehouses", "/dashboard/warehouse", null, "Warehouses", 7 },
-                    { 8, "orders", "/dashboard/orders", null, "Orders", 8 },
-                    { 9, "settings", "/dashboard/settings", null, "Settings", 9 },
-                    { 10, "help", "/dashboard/help", null, "Help", 10 }
-                });
-
-            migrationBuilder.UpdateData(
-                table: "users",
-                keyColumn: "UserId",
-                keyValue: 1,
-                column: "RoleId",
-                value: null);
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[,]
-                {
-                    { 1, "NAV:dashboard", 1, null },
-                    { 2, "NAV:products", 2, null },
-                    { 3, "NAV:vendors", 3, null },
-                    { 4, "NAV:procurement", 4, null },
-                    { 5, "NAV:receiving", 5, null },
-                    { 6, "NAV:stock", 6, null },
-                    { 7, "NAV:warehouses", 7, null },
-                    { 8, "NAV:orders", 8, null },
-                    { 9, "NAV:settings", 9, null },
-                    { 10, "NAV:help", 10, null }
-                });
-
-            migrationBuilder.InsertData(
-                table: "sub_nav_items",
-                columns: new[] { "SubNavItemId", "Code", "Href", "Icon", "Label", "NavItemId", "SortOrder" },
-                values: new object[,]
-                {
-                    { 1, "products.item", "/dashboard/products", null, "Item", 2, 1 },
-                    { 2, "products.category", "/dashboard/products/categories", null, "Category", 2, 2 },
-                    { 3, "products.brand", "/dashboard/products/brands", null, "Brand", 2, 3 },
-                    { 4, "products.item-type", "/dashboard/products/item-types", null, "Item Type", 2, 4 },
-                    { 5, "products.uom", "/dashboard/products/uoms", null, "UOM", 2, 5 },
-                    { 6, "products.configuration", "/dashboard/products/settings", null, "Configuration", 2, 6 },
-                    { 7, "settings.roles", "/dashboard/settings/roles", null, "Roles", 9, 1 },
-                    { 8, "settings.users", "/dashboard/settings/users", null, "Users", 9, 2 }
-                });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[,]
-                {
-                    { 11, "NAV:products.item", null, 1 },
-                    { 12, "NAV:products.category", null, 2 },
-                    { 13, "NAV:products.brand", null, 3 },
-                    { 14, "NAV:products.item-type", null, 4 },
-                    { 15, "NAV:products.uom", null, 5 },
-                    { 16, "NAV:products.configuration", null, 6 },
-                    { 17, "NAV:settings.roles", null, 7 },
-                    { 18, "NAV:settings.users", null, 8 }
-                });
-
-            migrationBuilder.CreateIndex(
-                name: "IX_users_RoleId",
-                table: "users",
-                column: "RoleId");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_nav_items_Code",
-                table: "nav_items",
-                column: "Code",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_permissions_Code",
-                table: "permissions",
-                column: "Code",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_permissions_NavItemId",
-                table: "permissions",
-                column: "NavItemId");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_permissions_SubNavItemId",
-                table: "permissions",
-                column: "SubNavItemId");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_role_permissions_PermissionId",
-                table: "role_permissions",
-                column: "PermissionId");
-
-            migrationBuilder.CreateIndex(
-                name: "IX_roles_auth_role_id",
-                table: "roles",
-                column: "auth_role_id",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_roles_Code",
-                table: "roles",
-                column: "Code",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_sub_nav_items_Code",
-                table: "sub_nav_items",
-                column: "Code",
-                unique: true);
-
-            migrationBuilder.CreateIndex(
-                name: "IX_sub_nav_items_NavItemId",
-                table: "sub_nav_items",
-                column: "NavItemId");
-
-            migrationBuilder.AddForeignKey(
-                name: "FK_users_roles_RoleId",
-                table: "users",
-                column: "RoleId",
-                principalTable: "roles",
-                principalColumn: "RoleId",
-                onDelete: ReferentialAction.Restrict);
-        }
-
-        /// <inheritdoc />
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.DropForeignKey(
-                name: "FK_users_roles_RoleId",
-                table: "users");
-
-            migrationBuilder.DropTable(
-                name: "role_permissions");
-
-            migrationBuilder.DropTable(
-                name: "permissions");
-
-            migrationBuilder.DropTable(
-                name: "roles");
-
-            migrationBuilder.DropTable(
-                name: "sub_nav_items");
-
-            migrationBuilder.DropTable(
-                name: "nav_items");
-
-            migrationBuilder.DropIndex(
-                name: "IX_users_RoleId",
-                table: "users");
-
-            migrationBuilder.DropColumn(
-                name: "RoleId",
-                table: "users");
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260720105238_AddLedgersNavSeed.cs

@@ -1,138 +0,0 @@
-using Microsoft.EntityFrameworkCore.Migrations;
-
-#nullable disable
-
-#pragma warning disable CA1814 // Prefer jagged arrays over multidimensional
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <inheritdoc />
-    public partial class AddLedgersNavSeed : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.InsertData(
-                table: "nav_items",
-                columns: new[] { "NavItemId", "Code", "Href", "Icon", "Label", "SortOrder" },
-                values: new object[] { 11, "ledgers", "/dashboard/ledgers", null, "Ledgers", 11 });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[] { 19, "NAV:ledgers", 11, null });
-
-            migrationBuilder.InsertData(
-                table: "sub_nav_items",
-                columns: new[] { "SubNavItemId", "Code", "Href", "Icon", "Label", "NavItemId", "SortOrder" },
-                values: new object[,]
-                {
-                    { 9, "ledgers.trial-balance", "/dashboard/ledgers/trial-balance", null, "Trial Balance", 11, 1 },
-                    { 10, "ledgers.balance-sheet", "/dashboard/ledgers/balance-sheet", null, "Balance Sheet", 11, 2 },
-                    { 11, "ledgers.general-ledger", "/dashboard/ledgers/general-ledger", null, "General Ledger", 11, 3 },
-                    { 12, "ledgers.profit-and-loss", "/dashboard/ledgers/profit-and-loss", null, "Profit & Loss", 11, 4 },
-                    { 13, "ledgers.cash-flow", "/dashboard/ledgers/cash-flow", null, "Cash Flow", 11, 5 },
-                    { 14, "ledgers.budget-vs-actual", "/dashboard/ledgers/budget-vs-actual", null, "Budget vs Actual", 11, 6 },
-                    { 15, "ledgers.bank-accounts", "/dashboard/ledgers/bank-accounts", null, "Cash / Bank Accounts", 11, 7 }
-                });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[,]
-                {
-                    { 20, "NAV:ledgers.trial-balance", null, 9 },
-                    { 21, "NAV:ledgers.balance-sheet", null, 10 },
-                    { 22, "NAV:ledgers.general-ledger", null, 11 },
-                    { 23, "NAV:ledgers.profit-and-loss", null, 12 },
-                    { 24, "NAV:ledgers.cash-flow", null, 13 },
-                    { 25, "NAV:ledgers.budget-vs-actual", null, 14 },
-                    { 26, "NAV:ledgers.bank-accounts", null, 15 }
-                });
-        }
-
-        /// <inheritdoc />
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 19);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 20);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 21);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 22);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 23);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 24);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 25);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 26);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 9);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 10);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 11);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 12);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 13);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 14);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 15);
-
-            migrationBuilder.DeleteData(
-                table: "nav_items",
-                keyColumn: "NavItemId",
-                keyValue: 11);
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260730061542_AddTaxReportNavSeed.cs

@@ -1,52 +0,0 @@
-using Microsoft.EntityFrameworkCore.Migrations;
-
-#nullable disable
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <inheritdoc />
-    public partial class AddTaxReportNavSeed : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.UpdateData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 15,
-                column: "SortOrder",
-                value: 8);
-
-            migrationBuilder.InsertData(
-                table: "sub_nav_items",
-                columns: new[] { "SubNavItemId", "Code", "Href", "Icon", "Label", "NavItemId", "SortOrder" },
-                values: new object[] { 16, "ledgers.tax-report", "/dashboard/ledgers/tax-report", null, "Tax Report", 11, 7 });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[] { 27, "NAV:ledgers.tax-report", null, 16 });
-        }
-
-        /// <inheritdoc />
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 27);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 16);
-
-            migrationBuilder.UpdateData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 15,
-                column: "SortOrder",
-                value: 7);
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260730105356_FixProcurementNavIdCollision.cs

@@ -1,82 +0,0 @@
-using Microsoft.EntityFrameworkCore.Migrations;
-
-#nullable disable
-
-#pragma warning disable CA1814 // Prefer jagged arrays over multidimensional
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <inheritdoc />
-    public partial class FixProcurementNavIdCollision : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.InsertData(
-                table: "sub_nav_items",
-                columns: new[] { "SubNavItemId", "Code", "Href", "Icon", "Label", "NavItemId", "SortOrder" },
-                values: new object[,]
-                {
-                    { 17, "procurement.requisitions", "/dashboard/procurement/requisitions", null, "Requisitions", 4, 1 },
-                    { 18, "procurement.rfqs", "/dashboard/procurement/rfqs", null, "RFQs", 4, 2 },
-                    { 19, "procurement.purchase-orders", "/dashboard/procurement/purchase-orders", null, "Purchase Orders", 4, 3 },
-                    { 20, "procurement.purchase-returns", "/dashboard/procurement/purchase-returns", null, "Purchase Returns", 4, 4 }
-                });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[,]
-                {
-                    { 28, "NAV:procurement.requisitions", null, 17 },
-                    { 29, "NAV:procurement.rfqs", null, 18 },
-                    { 30, "NAV:procurement.purchase-orders", null, 19 },
-                    { 31, "NAV:procurement.purchase-returns", null, 20 }
-                });
-        }
-
-        /// <inheritdoc />
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 28);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 29);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 30);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 31);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 17);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 18);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 19);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 20);
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260731113219_AddAccountsNavSeed.cs

@@ -1,106 +0,0 @@
-using Microsoft.EntityFrameworkCore.Migrations;
-
-#nullable disable
-
-#pragma warning disable CA1814 // Prefer jagged arrays over multidimensional
-
-namespace ERPCore.Infra.Persistence.Migrations
-{
-    /// <inheritdoc />
-    public partial class AddAccountsNavSeed : Migration
-    {
-        /// <inheritdoc />
-        protected override void Up(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.InsertData(
-                table: "nav_items",
-                columns: new[] { "NavItemId", "Code", "Href", "Icon", "Label", "SortOrder" },
-                values: new object[] { 12, "accounts", "/dashboard/accounts", null, "Accounts", 12 });
-
-            migrationBuilder.UpdateData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 26,
-                column: "Code",
-                value: "NAV:accounts.bank-accounts");
-
-            migrationBuilder.UpdateData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 15,
-                columns: new[] { "Code", "Href", "NavItemId", "SortOrder" },
-                values: new object[] { "accounts.bank-accounts", "/dashboard/accounts/bank-accounts", 12, 1 });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[] { 32, "NAV:accounts", 12, null });
-
-            migrationBuilder.InsertData(
-                table: "sub_nav_items",
-                columns: new[] { "SubNavItemId", "Code", "Href", "Icon", "Label", "NavItemId", "SortOrder" },
-                values: new object[,]
-                {
-                    { 21, "accounts.cheque-books", "/dashboard/accounts/cheque-books", null, "Cheque Books", 12, 2 },
-                    { 22, "accounts.received-cheques", "/dashboard/accounts/received-cheques", null, "Received Cheques", 12, 3 }
-                });
-
-            migrationBuilder.InsertData(
-                table: "permissions",
-                columns: new[] { "PermissionId", "Code", "NavItemId", "SubNavItemId" },
-                values: new object[,]
-                {
-                    { 33, "NAV:accounts.cheque-books", null, 21 },
-                    { 34, "NAV:accounts.received-cheques", null, 22 }
-                });
-        }
-
-        /// <inheritdoc />
-        protected override void Down(MigrationBuilder migrationBuilder)
-        {
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 32);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 33);
-
-            migrationBuilder.DeleteData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 34);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 21);
-
-            migrationBuilder.DeleteData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 22);
-
-            migrationBuilder.DeleteData(
-                table: "nav_items",
-                keyColumn: "NavItemId",
-                keyValue: 12);
-
-            migrationBuilder.UpdateData(
-                table: "permissions",
-                keyColumn: "PermissionId",
-                keyValue: 26,
-                column: "Code",
-                value: "NAV:ledgers.bank-accounts");
-
-            migrationBuilder.UpdateData(
-                table: "sub_nav_items",
-                keyColumn: "SubNavItemId",
-                keyValue: 15,
-                columns: new[] { "Code", "Href", "NavItemId", "SortOrder" },
-                values: new object[] { "ledgers.bank-accounts", "/dashboard/ledgers/bank-accounts", 11, 8 });
-        }
-    }
-}

Backend/ERPCore/Infra/Persistence/Migrations/20260731123720_production.cs

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

Backend/ERPCore/Program.cs

@@ -8,15 +8,17 @@ using ERPCore.Infra.UoW;
 using ERPCore.Repositories;
 using ERPCore.Repositories.Interfaces;
 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;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.OpenApi;
+using Npgsql;
 using Serilog;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -32,7 +34,10 @@ builder.Services.AddControllers()
 
 // EF Core + PostgreSQL
 builder.Services.AddDbContext<ErpDbContext>(o =>
-    o.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection")));
+{
+    o.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection"));
+    o.ConfigureWarnings(w => w.Ignore(RelationalEventId.PendingModelChangesWarning));
+});
 
 // ProblemDetails (RFC 7807) + domain-exception mapping
 builder.Services.AddProblemDetails();
@@ -72,11 +77,13 @@ builder.Services.AddScoped<IUnitOfWork, UnitOfWork>();
 builder.Services.AddScoped(typeof(IRepository<>), typeof(Repository<>));
 
 // Master-data services (docs/11 §2)
+builder.Services.AddScoped<ICustomerService, CustomerService>();
 builder.Services.AddScoped<IItemService, ItemService>();
 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>();
@@ -97,6 +104,18 @@ builder.Services.AddScoped<IFifoCostingService, FifoCostingService>();
 builder.Services.AddScoped<IStockService, StockService>();
 builder.Services.AddScoped<IGrnService, GrnService>();
 
+// Sales (Phase 1)
+builder.Services.AddScoped<ISalesPricingService, SalesPricingService>();
+builder.Services.AddScoped<ISalesDomainService, SalesDomainService>();
+builder.Services.AddScoped<ISalesPostingService, SalesPostingService>();
+builder.Services.AddScoped<ISalesDocumentWorkflowService, SalesDocumentWorkflowService>();
+builder.Services.AddScoped<ISalesMappingService, SalesMappingService>();
+builder.Services.AddScoped<ISalesInvoiceService, SalesInvoiceService>();
+builder.Services.AddScoped<ISalesSlipService, SalesSlipService>();
+builder.Services.AddScoped<IBundleSaleService, BundleSaleService>();
+builder.Services.AddScoped<ISalesPromotionSuggestionService, SalesPromotionSuggestionService>();
+builder.Services.AddScoped<ISalesReportService, SalesReportService>();
+
 // Stock transactions + reference data (docs/11 §5–6)
 builder.Services.AddScoped<IStockMutator, StockMutator>();
 builder.Services.AddScoped<IReasonCodeService, ReasonCodeService>();
@@ -171,7 +190,16 @@ var app = builder.Build();
 using (var scope = app.Services.CreateScope())
 {
     var db = scope.ServiceProvider.GetRequiredService<ErpDbContext>();
-    await DataSeeder.SeedAsync(db);
+   // await EnsureMigrationBaselineAsync(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();
@@ -188,3 +216,4 @@ app.UseAuthorization();
 app.MapControllers();
 app.MapHealthChecks("/health");
 app.Run();
+

Backend/ERPCore/Services/BundleSaleService.cs

@@ -0,0 +1,263 @@
+using ERPCore.Domain;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Infra.Auth;
+using ERPCore.Infra.UoW;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class BundleSaleService : IBundleSaleService
+{
+    private readonly IRepository<BundleSaleTemplate> _templates;
+    private readonly IRepository<BundleSale> _bundles;
+    private readonly IRepository<Customer> _customers;
+    private readonly IRepository<Item> _items;
+    private readonly IRepository<Uom> _uoms;
+    private readonly IRepository<Warehouse> _warehouses;
+    private readonly IRepository<User> _users;
+    private readonly ISalesDomainService _sales;
+    private readonly IUomConverter _uomConverter;
+    private readonly ISalesPostingService _posting;
+    private readonly ICurrentUser _currentUser;
+    private readonly INumberSequenceService _numbers;
+    private readonly IUnitOfWork _uow;
+
+    public BundleSaleService(
+        IRepository<BundleSale> bundles,
+        IRepository<BundleSaleTemplate> templates,
+        IRepository<Customer> customers,
+        IRepository<Item> items,
+        IRepository<Uom> uoms,
+        IRepository<Warehouse> warehouses,
+        IRepository<User> users,
+        ISalesDomainService sales,
+        IUomConverter uomConverter,
+        ISalesPostingService posting,
+        ICurrentUser currentUser,
+        INumberSequenceService numbers,
+        IUnitOfWork uow)
+    {
+        _templates = templates;
+        _bundles = bundles;
+        _customers = customers;
+        _items = items;
+        _uoms = uoms;
+        _warehouses = warehouses;
+        _users = users;
+        _sales = sales;
+        _uomConverter = uomConverter;
+        _posting = posting;
+        _currentUser = currentUser;
+        _numbers = numbers;
+        _uow = uow;
+    }
+
+    public async Task<PagedResponse<BundleSaleTemplateSummaryDto>> ListTemplatesAsync(PageQuery query, CancellationToken ct = default)
+    {
+        IQueryable<BundleSaleTemplate> q = _templates.Query().AsNoTracking().Include(x => x.Lines);
+        if (!string.IsNullOrWhiteSpace(query.Q))
+        {
+            var term = query.Q.Trim();
+            q = q.Where(x => EF.Functions.ILike(x.TemplateCode, $"%{term}%") || EF.Functions.ILike(x.TemplateName, $"%{term}%") || EF.Functions.ILike(x.Description ?? "", $"%{term}%"));
+        }
+        var total = await q.CountAsync(ct);
+        var rows = await q.OrderByDescending(x => x.BundleSaleTemplateId).Skip(query.Skip).Take(query.PageSize).ToListAsync(ct);
+        return PagedResponse<BundleSaleTemplateSummaryDto>.Create(rows.Select(x => new BundleSaleTemplateSummaryDto(
+            x.BundleSaleTemplateId, x.TemplateCode, x.TemplateName, x.Description, x.Status, x.Lines.Count, x.CreatedAt, x.UpdatedAt)).ToList(), query.Page, query.PageSize, total);
+    }
+
+    public async Task<BundleSaleTemplateDto?> GetTemplateAsync(int bundleSaleTemplateId, CancellationToken ct = default)
+    {
+        var template = await _templates.Query().AsNoTracking().Include(x => x.Lines).FirstOrDefaultAsync(x => x.BundleSaleTemplateId == bundleSaleTemplateId, ct);
+        return template is null ? null : new BundleSaleTemplateDto(
+            template.BundleSaleTemplateId,
+            template.TemplateCode,
+            template.TemplateName,
+            template.Description,
+            template.Status,
+            template.CreatedAt,
+            template.UpdatedAt,
+            template.Lines.OrderBy(x => x.SortOrder).Select(x => new BundleSaleTemplateLineDto(
+                x.BundleSaleTemplateLineId, x.ItemId, x.UomId, x.WarehouseId, x.Qty, x.UnitPrice, x.IncludeInBundle, x.SortOrder)).ToList());
+    }
+
+    public async Task<PagedResponse<BundleSaleSummaryDto>> ListAsync(PageQuery query, BundleSaleStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default)
+    {
+        IQueryable<BundleSale> q = _bundles.Query().AsNoTracking().Include(x => x.Lines);
+        if (!string.IsNullOrWhiteSpace(query.Q))
+        {
+            var term = query.Q.Trim();
+            q = q.Where(x => EF.Functions.ILike(x.BundleNo, $"%{term}%") || EF.Functions.ILike(x.BundleName, $"%{term}%") || EF.Functions.ILike(x.BundleCode, $"%{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.BundleSaleId).Skip(query.Skip).Take(query.PageSize).ToListAsync(ct);
+        return PagedResponse<BundleSaleSummaryDto>.Create(rows.Select(MapSummary).ToList(), query.Page, query.PageSize, total);
+    }
+
+    public async Task<BundleSaleDto?> GetAsync(int bundleSaleId, CancellationToken ct = default)
+    {
+        var bundle = await _bundles.Query().AsNoTracking().Include(x => x.Lines).FirstOrDefaultAsync(x => x.BundleSaleId == bundleSaleId, ct);
+        return bundle is null ? null : Map(bundle);
+    }
+
+    public Task<BundleSalePostingCheckDto> CheckPostingAsync(int bundleSaleId, CancellationToken ct = default)
+        => _posting.CheckBundleAsync(bundleSaleId, ct);
+
+    public async Task<BundleSaleDto> CreateAsync(CreateBundleSaleRequest request, CancellationToken ct = default)
+    {
+        await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, request.CashierUserId, true, ct);
+        var template = await _templates.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstAsync(x => x.BundleSaleTemplateId == request.BundleSaleTemplateId, ct);
+        var bundle = new BundleSale
+        {
+            BundleNo = await _numbers.NextAsync(DocumentTypes.BundleSale, ct),
+            BundleDate = DateTime.UtcNow,
+            CustomerId = request.CustomerId,
+            WarehouseId = request.WarehouseId,
+            CashierUserId = request.CashierUserId,
+            BundleSaleTemplateId = request.BundleSaleTemplateId,
+            BundleName = request.BundleName,
+            BundleCode = string.Empty,
+            Status = BundleSaleStatus.Draft,
+            CreatedAt = DateTime.UtcNow
+        };
+        bundle.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
+        bundle.Lines = await BuildLinesAsync(template, request.WarehouseId, request.Lines, ct);
+        Recalculate(bundle, request.BundlePrice);
+        bundle.BundleCode = $"{bundle.BundleNo}-B";
+        await _bundles.AddAsync(bundle, ct);
+        bundle.ConcurrencyStamp = 1;
+        await _uow.SaveChangesAsync(ct);
+        return Map(bundle);
+    }
+
+    public async Task<BundleSaleDto> UpdateAsync(int bundleSaleId, UpdateBundleSaleRequest request, CancellationToken ct = default)
+    {
+        var bundle = await _bundles.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.BundleSaleId == bundleSaleId, ct)
+            ?? throw new NotFoundException($"Bundle sale {bundleSaleId} was not found.");
+        if (bundle.Status != BundleSaleStatus.Draft)
+            throw new ConflictException($"Bundle sale {bundleSaleId} is {bundle.Status} and cannot be edited.");
+
+        await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, request.CashierUserId, true, ct);
+        var template = await _templates.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstAsync(x => x.BundleSaleTemplateId == request.BundleSaleTemplateId, ct);
+        bundle.CustomerId = request.CustomerId;
+        bundle.WarehouseId = request.WarehouseId;
+        bundle.CashierUserId = request.CashierUserId;
+        bundle.BundleSaleTemplateId = request.BundleSaleTemplateId;
+        bundle.BundleName = request.BundleName;
+        bundle.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
+        bundle.Lines.Clear();
+        foreach (var line in await BuildLinesAsync(template, request.WarehouseId, request.Lines, ct)) bundle.Lines.Add(line);
+        Recalculate(bundle, request.BundlePrice);
+        bundle.UpdatedAt = DateTime.UtcNow;
+        bundle.ConcurrencyStamp++;
+        await _uow.SaveChangesAsync(ct);
+        return Map(bundle);
+    }
+
+    public async Task<BundleSaleDto> PostAsync(int bundleSaleId, CancellationToken ct = default)
+        {
+            await _posting.PostBundleAsync(bundleSaleId, ct);
+            var bundle = await _bundles.Query().AsNoTracking().Include(x => x.Lines)
+                .FirstAsync(x => x.BundleSaleId == bundleSaleId, ct);
+            return Map(bundle);
+        }
+
+    public async Task<BundleSaleDto> CancelAsync(int bundleSaleId, CancellationToken ct = default)
+    {
+        var bundle = await _bundles.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.BundleSaleId == bundleSaleId, ct)
+            ?? throw new NotFoundException($"Bundle sale {bundleSaleId} was not found.");
+        if (bundle.Status != BundleSaleStatus.Draft)
+            throw new ConflictException($"Bundle sale {bundleSaleId} is {bundle.Status} and cannot be cancelled.");
+        bundle.Status = BundleSaleStatus.Cancelled;
+        bundle.UpdatedAt = DateTime.UtcNow;
+        bundle.ConcurrencyStamp++;
+        await _uow.SaveChangesAsync(ct);
+        return Map(bundle);
+    }
+
+    private async Task<List<BundleSaleLine>> BuildLinesAsync(
+        BundleSaleTemplate template, int warehouseId, IReadOnlyList<CreateBundleSaleTemplateLineRequest> requestLines, CancellationToken ct)
+    {
+        var lines = new List<BundleSaleLine>();
+        var sourceLines = requestLines.Count > 0
+            ? requestLines.OrderBy(x => x.SortOrder).ToList()
+            : template.Lines.OrderBy(x => x.SortOrder).Select(x => new CreateBundleSaleTemplateLineRequest
+            {
+                ItemId = x.ItemId,
+                UomId = x.UomId,
+                WarehouseId = x.WarehouseId,
+                Qty = x.Qty,
+                UnitPrice = x.UnitPrice,
+                IncludeInBundle = x.IncludeInBundle,
+                SortOrder = x.SortOrder
+            }).ToList();
+
+        foreach (var r in sourceLines)
+        {
+            if (r.Qty <= 0)
+                throw new DomainException(ErrorCodes.Validation, "Bundle line quantity must be greater than zero.", 422);
+
+            // Bundle sales use the header warehouse as the source of truth for stock and pricing.
+            // Keep any per-line warehouse input from drifting away from the header.
+            var lineWarehouseId = warehouseId;
+
+            var item = await _items.Query().AsNoTracking().FirstAsync(x => x.ItemId == r.ItemId, ct);
+            await _sales.ValidateSalesLineAsync(warehouseId, r.ItemId, r.UomId, lineWarehouseId, r.Qty, 0m, null, ct);
+
+            // Keep the entered UOM on the line and snapshot the base quantity beside it, the
+            // same shape as invoices and slips. Qty and UnitPrice stay a matching pair in the
+            // entered UOM so LineTotal — which Recalculate rolls into the header — is the
+            // value the user priced; only QtyBase crosses into the base-UOM stock engine.
+            var factor = await _uomConverter.ResolveFactorAsync(item, r.UomId, ct);
+            var calc = _sales.ComputeLine(r.Qty, 0m, r.UnitPrice, SalesDiscountMode.Amount, 0m, 0m, 0m, 0m, false);
+            lines.Add(new BundleSaleLine
+            {
+                ItemId = r.ItemId,
+                Description = item.Name,
+                Qty = r.Qty,
+                UomId = r.UomId,
+                QtyBase = UomConverter.ApplyFactor(r.Qty, factor),
+                ConversionFactor = factor,
+                WarehouseId = lineWarehouseId,
+                UnitPrice = r.UnitPrice,
+                LineTotal = calc.LineTotal,
+                IncludeInBundle = r.IncludeInBundle,
+                IsComponent = true,
+                ParentLineId = null
+            });
+        }
+        return lines;
+    }
+
+    private static void Recalculate(BundleSale bundle, decimal bundlePrice)
+    {
+        bundle.ComponentSubtotal = bundle.Lines.Where(x => x.IncludeInBundle).Sum(x => x.LineTotal);
+        bundle.BundlePrice = bundlePrice;
+        bundle.MarginAmount = bundle.BundlePrice - bundle.ComponentSubtotal;
+        bundle.DiscountTotal = Math.Max(0m, bundle.ComponentSubtotal - bundle.BundlePrice);
+        bundle.TaxTotal = 0m;
+        bundle.GrandTotal = bundle.BundlePrice + bundle.TaxTotal;
+    }
+
+    private static BundleSaleSummaryDto MapSummary(BundleSale x) => new(
+        x.BundleSaleId, x.BundleNo, x.BundleDate, x.CustomerId, x.CustomerSnapshotName, x.WarehouseId, x.BundleName, x.BundleCode, x.Status, x.ComponentSubtotal, x.BundlePrice, x.GrandTotal, x.CreatedAt);
+
+    private static BundleSaleDto Map(BundleSale x) => new(
+        x.BundleSaleId, x.BundleNo, x.BundleDate, x.CustomerId, x.CustomerSnapshotName, x.WarehouseId, x.CashierUserId, x.BundleSaleTemplateId,
+        x.BundleName, x.BundleCode, x.Status, x.ComponentSubtotal, x.BundlePrice, x.MarginAmount, x.DiscountTotal, x.TaxTotal, x.GrandTotal,
+        x.CreatedAt, x.UpdatedAt,
+        x.Lines.Select(l => new BundleSaleLineDto(l.BundleSaleLineId, l.ItemId, l.Description, l.Qty, l.UomId, l.WarehouseId, l.UnitPrice, l.LineTotal, l.IncludeInBundle, l.IsComponent, l.ParentLineId)).ToList());
+
+}

Backend/ERPCore/Services/CustomerService.cs

@@ -0,0 +1,168 @@
+using ERPCore.Common.Http;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Customers;
+using ERPCore.Infra.UoW;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class CustomerService : ICustomerService
+{
+    private readonly IRepository<Customer> _customers;
+    private readonly IRepository<Warehouse> _warehouses;
+    private readonly IUnitOfWork _uow;
+
+    public CustomerService(IRepository<Customer> customers, IRepository<Warehouse> warehouses, IUnitOfWork uow)
+    {
+        _customers = customers;
+        _warehouses = warehouses;
+        _uow = uow;
+    }
+
+    public async Task<PagedResponse<CustomerDto>> ListAsync(PageQuery query, EntityStatus? status, CustomerType? customerType, CancellationToken ct = default)
+    {
+        var q = _customers.Query().AsNoTracking();
+        if (!string.IsNullOrWhiteSpace(query.Q))
+        {
+            var term = query.Q.Trim();
+            q = q.Where(c => EF.Functions.ILike(c.Name, $"%{term}%")
+                             || EF.Functions.ILike(c.CustomerCode, $"%{term}%")
+                             || (c.DisplayName != null && EF.Functions.ILike(c.DisplayName, $"%{term}%")));
+        }
+        if (status is not null) q = q.Where(c => c.Status == status);
+        if (customerType is not null) q = q.Where(c => c.CustomerType == customerType);
+
+        var total = await q.CountAsync(ct);
+        var rows = await q.OrderBy(c => c.Name)
+            .Skip(query.Skip).Take(query.PageSize)
+            .Select(c => new CustomerDto(
+                c.CustomerId, c.CustomerCode, c.CustomerType, c.Name, c.DisplayName, c.Phone, c.Email,
+                c.AddressLine1, c.AddressLine2, c.City, c.Country, c.TaxRegistrationNo,
+                c.CreditLimit, c.CreditDays, c.DefaultWarehouseId, c.Status, c.CreatedAt, c.UpdatedAt))
+            .ToListAsync(ct);
+
+        return PagedResponse<CustomerDto>.Create(rows, query.Page, query.PageSize, total);
+    }
+
+    public async Task<ETagged<CustomerDto>?> GetAsync(int customerId, CancellationToken ct = default)
+    {
+        var customer = await _customers.Query().AsNoTracking()
+            .FirstOrDefaultAsync(c => c.CustomerId == customerId, ct);
+        return customer is null ? null : new ETagged<CustomerDto>(Map(customer), customer.RowVersion);
+    }
+
+    public async Task<ETagged<CustomerDto>> CreateAsync(CreateCustomerRequest request, CancellationToken ct = default)
+    {
+        var code = request.CustomerCode.Trim();
+        var name = request.Name.Trim();
+
+        if (await _customers.Query().AnyAsync(c => c.CustomerCode.ToLower() == code.ToLower(), ct))
+            throw new ConflictException($"A customer code '{code}' already exists.");
+
+        if (!string.IsNullOrWhiteSpace(request.Email))
+        {
+            var email = request.Email.Trim();
+            if (await _customers.Query().AnyAsync(c => c.Email != null && c.Email.ToLower() == email.ToLower(), ct))
+                throw new ConflictException($"A customer with email '{email}' already exists.");
+        }
+
+        if (request.DefaultWarehouseId is not null)
+        {
+            var exists = await _warehouses.Query().AnyAsync(w => w.WarehouseId == request.DefaultWarehouseId, ct);
+            if (!exists) throw new NotFoundException($"Warehouse {request.DefaultWarehouseId} was not found.");
+        }
+
+        var customer = new Customer
+        {
+            CustomerCode = code,
+            CustomerType = request.CustomerType,
+            Name = name,
+            DisplayName = Normalize(request.DisplayName),
+            Phone = Normalize(request.Phone),
+            Email = Normalize(request.Email),
+            AddressLine1 = Normalize(request.AddressLine1),
+            AddressLine2 = Normalize(request.AddressLine2),
+            City = Normalize(request.City),
+            Country = Normalize(request.Country),
+            TaxRegistrationNo = Normalize(request.TaxRegistrationNo),
+            CreditLimit = request.CreditLimit,
+            CreditDays = request.CreditDays,
+            DefaultWarehouseId = request.DefaultWarehouseId,
+            Status = EntityStatus.Active,
+            CreatedAt = DateTime.UtcNow
+        };
+
+        await _customers.AddAsync(customer, ct);
+        await _uow.SaveChangesAsync(ct);
+
+        return new ETagged<CustomerDto>(Map(customer), customer.RowVersion);
+    }
+
+    public async Task<ETagged<CustomerDto>> UpdateAsync(int customerId, UpdateCustomerRequest request, uint expectedRowVersion, CancellationToken ct = default)
+    {
+        var customer = await _customers.GetByIdAsync(customerId, ct)
+            ?? throw new NotFoundException($"Customer {customerId} was not found.");
+
+        if (customer.RowVersion != expectedRowVersion)
+            throw new DomainException(ErrorCodes.ConcurrencyConflict, "The customer was modified by another request.", 412);
+
+        var code = request.CustomerCode.Trim();
+        var name = request.Name.Trim();
+
+        if (!string.Equals(customer.CustomerCode, code, StringComparison.Ordinal)
+            && await _customers.Query().AnyAsync(c => c.CustomerCode.ToLower() == code.ToLower() && c.CustomerId != customerId, ct))
+            throw new ConflictException($"A customer code '{code}' already exists.");
+
+        if (!string.Equals(customer.Email, request.Email?.Trim(), StringComparison.OrdinalIgnoreCase)
+            && !string.IsNullOrWhiteSpace(request.Email)
+            && await _customers.Query().AnyAsync(c => c.Email != null && c.Email.ToLower() == request.Email!.Trim().ToLower() && c.CustomerId != customerId, ct))
+            throw new ConflictException($"A customer with email '{request.Email.Trim()}' already exists.");
+
+        if (request.DefaultWarehouseId is not null)
+        {
+            var exists = await _warehouses.Query().AnyAsync(w => w.WarehouseId == request.DefaultWarehouseId, ct);
+            if (!exists) throw new NotFoundException($"Warehouse {request.DefaultWarehouseId} was not found.");
+        }
+
+        customer.CustomerCode = code;
+        customer.CustomerType = request.CustomerType;
+        customer.Name = name;
+        customer.DisplayName = Normalize(request.DisplayName);
+        customer.Phone = Normalize(request.Phone);
+        customer.Email = Normalize(request.Email);
+        customer.AddressLine1 = Normalize(request.AddressLine1);
+        customer.AddressLine2 = Normalize(request.AddressLine2);
+        customer.City = Normalize(request.City);
+        customer.Country = Normalize(request.Country);
+        customer.TaxRegistrationNo = Normalize(request.TaxRegistrationNo);
+        customer.CreditLimit = request.CreditLimit;
+        customer.CreditDays = request.CreditDays;
+        customer.DefaultWarehouseId = request.DefaultWarehouseId;
+        customer.UpdatedAt = DateTime.UtcNow;
+
+        await _uow.SaveChangesAsync(ct);
+        return new ETagged<CustomerDto>(Map(customer), customer.RowVersion);
+    }
+
+    public async Task SetStatusAsync(int customerId, EntityStatus status, CancellationToken ct = default)
+    {
+        var customer = await _customers.GetByIdAsync(customerId, ct)
+            ?? throw new NotFoundException($"Customer {customerId} was not found.");
+
+        customer.Status = status;
+        customer.UpdatedAt = DateTime.UtcNow;
+        await _uow.SaveChangesAsync(ct);
+    }
+
+    private static CustomerDto Map(Customer c) => new(
+        c.CustomerId, c.CustomerCode, c.CustomerType, c.Name, c.DisplayName, c.Phone, c.Email,
+        c.AddressLine1, c.AddressLine2, c.City, c.Country, c.TaxRegistrationNo,
+        c.CreditLimit, c.CreditDays, c.DefaultWarehouseId, c.Status, c.CreatedAt, c.UpdatedAt);
+
+    private static string? Normalize(string? value) => string.IsNullOrWhiteSpace(value) ? null : value.Trim();
+}

Backend/ERPCore/Services/GrnService.cs

@@ -7,6 +7,7 @@ using ERPCore.Infra.Auth;
 using ERPCore.Infra.UoW;
 using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
 using ERPCore.System.Errors;
 using Microsoft.EntityFrameworkCore;
 
@@ -138,6 +139,12 @@ public sealed class GrnService : IGrnService
             if (input.BinId is not null && !await _bins.Query().AnyAsync(b => b.BinId == input.BinId && b.WarehouseId == request.WarehouseId, ct))
                 throw new DomainException(ErrorCodes.Validation, $"Bin {input.BinId} is not in warehouse {request.WarehouseId}.", 422);
 
+            // Resolve the base quantity at entry. This rejects a UOM the item cannot be
+            // received in while the GRN is still a draft, and snapshots the factor so confirm
+            // (and any later reversal) reproduces exactly this quantity.
+            var conversionFactor = await _uomConverter.ResolveFactorAsync(item, input.UomId, ct);
+            var qtyBaseEntered = UomConverter.ApplyFactor(input.Qty, conversionFactor);
+
             // Cost: for a PO line, the PO price is used unless an override is entered (then it
             // wins and a variance is recorded against the PO snapshot — docs/02-SECURITY C.3,
             // revised). Direct receipts always use the entered cost.
@@ -150,10 +157,13 @@ public sealed class GrnService : IGrnService
                 if (poLine.ItemId != input.ItemId)
                     throw new DomainException(ErrorCodes.Validation, $"PO line {input.PoLineId} is for a different item.", 422);
 
-                var openQty = poLine.Qty - poLine.QtyReceived;
-                if (input.Qty > openQty * (1 + OverReceiptTolerance))
+                // Compare in base UOM: a GRN may legitimately receive in a different UOM from
+                // the one the PO was raised in (10 BOX ordered, 120 PCS delivered), and
+                // comparing the two raw numbers would reject that valid receipt.
+                var openQtyBase = poLine.QtyBase - poLine.QtyReceivedBase;
+                if (qtyBaseEntered > openQtyBase * (1 + OverReceiptTolerance))
                     throw new DomainException(ErrorCodes.OverReceiptTolerance,
-                        $"Receiving {input.Qty} exceeds the open quantity {openQty} on PO line {input.PoLineId}.", 422);
+                        $"Receiving {input.Qty} ({qtyBaseEntered} base) exceeds the open quantity {openQtyBase} base on PO line {input.PoLineId}.", 422);
 
                 poUnitPrice = poLine.UnitPrice;
                 unitCost = input.UnitCost > 0 ? input.UnitCost : poLine.UnitPrice;
@@ -178,6 +188,8 @@ public sealed class GrnService : IGrnService
                 BinId = input.BinId,
                 Batch = batch, // navigation so EF fixes up BatchId once the batch is inserted
                 Qty = input.Qty,
+                QtyBase = qtyBaseEntered,
+                ConversionFactor = conversionFactor,
                 UnitCost = unitCost,
                 PoUnitPrice = poUnitPrice,
                 DiscountPct = input.DiscountPct,
@@ -234,10 +246,13 @@ public sealed class GrnService : IGrnService
         {
             foreach (var line in grn.Lines.OrderBy(l => l.GrnLineId))
             {
-                var item = await _items.Query().AsNoTracking().FirstAsync(i => i.ItemId == line.ItemId, token);
                 // FIFO layer costs at the after-discount net price; VAT is recoverable and never
-                // enters stock value (docs/10 FR-GRN-06, revised).
-                var (qtyBase, unitCostBase) = await ToBaseAsync(item, line.UomId, line.Qty, line.NetUnitCost, token);
+                // enters stock value (docs/10 FR-GRN-06, revised). Quantity and cost come from
+                // the factor snapshotted at line creation, not a fresh lookup — see GrnLine.QtyBase.
+                var qtyBase = line.QtyBase;
+                var unitCostBase = line.ConversionFactor == 1m
+                    ? line.NetUnitCost
+                    : Math.Round(line.NetUnitCost / line.ConversionFactor, 6, MidpointRounding.AwayFromZero);
 
                 var layer = await _fifo.CreateInboundLayerAsync(
                     line.ItemId, grn.WarehouseId, line.BatchId, null, line.GrnLineId,
@@ -258,7 +273,13 @@ public sealed class GrnService : IGrnService
                 if (line.PoLineId is not null)
                 {
                     var poLine = await _poLines.GetByIdAsync(line.PoLineId.Value, token);
-                    if (poLine is not null) poLine.QtyReceived += line.Qty;
+                    if (poLine is not null)
+                    {
+                        // Accrue in base so receipts in a UOM other than the PO's still add up.
+                        // QtyReceived is kept in the PO's own UOM for display only.
+                        poLine.QtyReceivedBase += qtyBase;
+                        poLine.QtyReceived = UomConverter.FromBase(poLine.QtyReceivedBase, poLine.ConversionFactor);
+                    }
                 }
             }
 
@@ -345,22 +366,14 @@ public sealed class GrnService : IGrnService
         return created; // linked via GrnLine.Batch navigation; FK fixed up on SaveChanges
     }
 
-    /// <summary>
-    /// Delegates to the shared <see cref="IUomConverter"/>. This was a private method here
-    /// until manufacturing needed the same conversion for stage stock inputs; behaviour is
-    /// identical, so receive costing is unchanged.
-    /// </summary>
-    private Task<(decimal QtyBase, decimal UnitCostBase)> ToBaseAsync(
-        Item item, int uomId, decimal qty, decimal unitCostPerUom, CancellationToken ct)
-        => _uomConverter.ToBaseAsync(item, uomId, qty, unitCostPerUom, ct);
-
     private async Task UpdatePoStatusAsync(int? poId, CancellationToken ct)
     {
         if (poId is null) return;
         var po = await _pos.Query().Include(p => p.Lines).FirstOrDefaultAsync(p => p.PoId == poId, ct);
         if (po is null) return;
 
-        po.Status = po.Lines.All(l => l.QtyReceived >= l.Qty)
+        // Base-vs-base: QtyReceived is a denormalized display figure and must not gate closing.
+        po.Status = po.Lines.All(l => l.QtyReceivedBase >= l.QtyBase)
             ? PurchaseOrderStatus.FullyReceived
             : PurchaseOrderStatus.PartiallyReceived;
         po.UpdatedAt = DateTime.UtcNow;

Backend/ERPCore/Services/Interfaces/IBundleSaleService.cs

@@ -0,0 +1,19 @@
+using ERPCore.Common.Http;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface IBundleSaleService
+{
+    Task<PagedResponse<BundleSaleTemplateSummaryDto>> ListTemplatesAsync(PageQuery query, CancellationToken ct = default);
+    Task<BundleSaleTemplateDto?> GetTemplateAsync(int bundleSaleTemplateId, CancellationToken ct = default);
+    Task<PagedResponse<BundleSaleSummaryDto>> ListAsync(PageQuery query, BundleSaleStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default);
+    Task<BundleSaleDto?> GetAsync(int bundleSaleId, CancellationToken ct = default);
+    Task<BundleSalePostingCheckDto> CheckPostingAsync(int bundleSaleId, CancellationToken ct = default);
+    Task<BundleSaleDto> CreateAsync(CreateBundleSaleRequest request, CancellationToken ct = default);
+    Task<BundleSaleDto> UpdateAsync(int bundleSaleId, UpdateBundleSaleRequest request, CancellationToken ct = default);
+    Task<BundleSaleDto> PostAsync(int bundleSaleId, CancellationToken ct = default);
+    Task<BundleSaleDto> CancelAsync(int bundleSaleId, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ICustomerService.cs

@@ -0,0 +1,15 @@
+using ERPCore.Common.Http;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Customers;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ICustomerService
+{
+    Task<PagedResponse<CustomerDto>> ListAsync(PageQuery query, EntityStatus? status, CustomerType? customerType, CancellationToken ct = default);
+    Task<ETagged<CustomerDto>?> GetAsync(int customerId, CancellationToken ct = default);
+    Task<ETagged<CustomerDto>> CreateAsync(CreateCustomerRequest request, CancellationToken ct = default);
+    Task<ETagged<CustomerDto>> UpdateAsync(int customerId, UpdateCustomerRequest request, uint expectedRowVersion, CancellationToken ct = default);
+    Task SetStatusAsync(int customerId, EntityStatus status, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesDocumentWorkflowService.cs

@@ -0,0 +1,9 @@
+using ERPCore.Domain.Entities;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesDocumentWorkflowService
+{
+    Task<SalesInvoice> LoadEditableInvoiceAsync(int salesInvoiceId, uint expectedRowVersion, CancellationToken ct = default);
+    Task<SalesSlip> LoadEditableSlipAsync(int salesSlipId, uint expectedRowVersion, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesDomainService.cs

@@ -0,0 +1,51 @@
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Sales;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesDomainService
+{
+    Task ValidateSalesHeaderAsync(
+        int customerId,
+        int warehouseId,
+        int? cashierUserId,
+        bool requireCashierUser,
+        CancellationToken ct = default);
+
+    Task ValidateSalesLineAsync(
+        int headerWarehouseId,
+        int lineItemId,
+        int lineUomId,
+        int lineWarehouseId,
+        decimal qty,
+        decimal freeQty,
+        int? parentLineId,
+        CancellationToken ct = default);
+
+    Task<SalesPriceResolution> ResolveLinePriceAsync(
+        int itemId,
+        int warehouseId,
+        decimal? requestedUnitPrice,
+        bool allowManualOverride,
+        CancellationToken ct = default);
+
+    SalesLineComputation ComputeLine(
+        decimal qty,
+        decimal freeQty,
+        decimal unitPrice,
+        SalesDiscountMode discountMode,
+        decimal discountPct,
+        decimal discountValue,
+        decimal discountAmount,
+        decimal taxPct,
+        bool isFreeIssue);
+
+    Task<bool> IsStockedItemAsync(int itemId, CancellationToken ct = default);
+}
+
+public sealed record SalesLineComputation(
+    decimal Gross,
+    decimal DiscountTotal,
+    decimal NetUnitPrice,
+    decimal LineTotal,
+    decimal TaxAmount);

Backend/ERPCore/Services/Interfaces/ISalesInvoiceService.cs

@@ -0,0 +1,17 @@
+using ERPCore.Common.Http;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Services.Interfaces;
+
+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);
+    Task<SalesInvoiceDto> CancelAsync(int salesInvoiceId, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesMappingService.cs

@@ -0,0 +1,12 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Dtos.Sales;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesMappingService
+{
+    SalesInvoiceTotalsDto MapInvoiceTotals(SalesInvoice invoice);
+    SalesSlipTotalsDto MapSlipTotals(SalesSlip slip);
+    SalesInvoiceDto MapInvoice(SalesInvoice invoice);
+    SalesSlipDto MapSlip(SalesSlip slip);
+}

Backend/ERPCore/Services/Interfaces/ISalesPostingService.cs

@@ -0,0 +1,14 @@
+using ERPCore.Dtos.Sales;
+
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesPostingService
+{
+    Task<SalesInvoicePostingCheckDto> CheckInvoiceAsync(int salesInvoiceId, CancellationToken ct = default);
+    Task<SalesSlipPostingCheckDto> CheckSlipAsync(int salesSlipId, CancellationToken ct = default);
+    Task<BundleSalePostingCheckDto> CheckBundleAsync(int bundleSaleId, CancellationToken ct = default);
+
+    Task PostInvoiceAsync(int salesInvoiceId, CancellationToken ct = default);
+    Task PostSlipAsync(int salesSlipId, CancellationToken ct = default);
+    Task PostBundleAsync(int bundleSaleId, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesPricingService.cs

@@ -0,0 +1,16 @@
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesPricingService
+{
+    Task<SalesPriceResolution> ResolveAsync(
+        int itemId,
+        int warehouseId,
+        decimal? requestedUnitPrice,
+        bool allowManualOverride,
+        CancellationToken ct = default);
+}
+
+public sealed record SalesPriceResolution(
+    decimal UnitPrice,
+    string PriceSource,
+    decimal BaseCost);

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

@@ -0,0 +1,16 @@
+using ERPCore.Dtos.Sales;
+
+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);
+    Task<IReadOnlyList<SalesWarehouseSummaryRowDto>> WarehouseSummaryAsync(DateOnly from, DateOnly to, int? warehouseId, CancellationToken ct = default);
+    Task<IReadOnlyList<SalesDiscountSummaryRowDto>> DiscountSummaryAsync(DateOnly from, DateOnly to, CancellationToken ct = default);
+    Task<IReadOnlyList<SalesFreeIssueSummaryRowDto>> FreeIssueSummaryAsync(DateOnly from, DateOnly to, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/ISalesSlipService.cs

@@ -0,0 +1,19 @@
+using ERPCore.Common.Http;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Services.Interfaces;
+
+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);
+    Task<SalesSlipDto> CancelAsync(int salesSlipId, CancellationToken ct = default);
+}

Backend/ERPCore/Services/Interfaces/IUomConverter.cs

@@ -1,4 +1,5 @@
 using ERPCore.Domain.Entities;
+using ERPCore.Dtos.Uoms;
 
 namespace ERPCore.Services.Interfaces;
 
@@ -32,4 +33,29 @@ public interface IUomConverter
     /// consumes, not from the document).
     /// </summary>
     Task<decimal> ToBaseQtyAsync(Item item, int uomId, decimal qty, CancellationToken ct = default);
+
+    /// <summary>
+    /// The single factor lookup every other method is built on: <c>1</c> when
+    /// <paramref name="uomId"/> is already the base UOM, otherwise the item's conversion
+    /// factor from that UOM to base. Throws 422 when none is defined.
+    /// </summary>
+    /// <remarks>
+    /// Callers that persist a line should store this alongside the quantity so posting
+    /// reads a snapshot instead of re-resolving — a factor edited between save and post
+    /// must never change what an already-saved document posts.
+    /// </remarks>
+    Task<decimal> ResolveFactorAsync(Item item, int uomId, CancellationToken ct = default);
+
+    /// <summary>
+    /// Every UOM <paramref name="itemId"/> may be transacted in — base UOM first, then each
+    /// conversion source, ordered by name.
+    /// </summary>
+    Task<IReadOnlyList<AllowedUomDto>> GetAllowedUomsAsync(int itemId, CancellationToken ct = default);
+
+    /// <summary>
+    /// Entry-time guard: throws 422 naming the allowed units when <paramref name="uomId"/>
+    /// is neither the item's base UOM nor a UOM it has a conversion from. Call this when a
+    /// document line is created so the user is told at entry, not by a cryptic failure at post.
+    /// </summary>
+    Task ValidateUomAsync(Item item, int uomId, CancellationToken ct = default);
 }

Backend/ERPCore/Services/ItemService.cs

@@ -148,6 +148,15 @@ public sealed class ItemService : IItemService
             request.CategoryId, request.SubCategoryId, request.BrandId,
             request.BaseUomId, request.DefaultVendorId, ct);
 
+        // Conversions are stored as <other> → base. Repointing the base UOM would leave every
+        // existing row aimed at a UOM that is no longer the base: invisible to IUomConverter,
+        // filtered out of the allowed-UOM list, and unfixable through the conversions editor
+        // (which would 422 on re-save). Make the user clear them deliberately instead.
+        if (request.BaseUomId != item.BaseUomId && item.UomConversions.Count > 0)
+            throw new DomainException(ErrorCodes.Validation,
+                $"Item {item.Sku} has {item.UomConversions.Count} UOM conversion(s) defined against base UOM {item.BaseUomId}. " +
+                "Remove them before changing the base UOM, then re-enter them against the new base.", 422);
+
         item.Sku = request.Sku.Trim();
         item.Name = request.Name.Trim();
         item.Description = request.Description;
@@ -240,6 +249,26 @@ public sealed class ItemService : IItemService
             if (!await _uoms.Query().AnyAsync(u => u.UomId == uomId, ct))
                 throw new DomainException(ErrorCodes.Validation, $"UOM {uomId} does not exist.", 422);
 
+        // Conversions are one-directional: always <other> → base. IUomConverter looks up
+        // exactly that shape and never inverts a factor, so a row saved the other way round
+        // would persist happily, render in the UI, and then be invisible at post time. Reject
+        // it here instead of letting it fail later as an unexplained 422.
+        foreach (var c in request.Conversions)
+        {
+            if (c.ToUom != item.BaseUomId)
+                throw new DomainException(ErrorCodes.Validation,
+                    $"Conversion {c.FromUom} → {c.ToUom} is invalid: conversions must convert to the item's base UOM ({item.BaseUomId}).", 422);
+            if (c.FromUom == c.ToUom)
+                throw new DomainException(ErrorCodes.Validation,
+                    $"Conversion {c.FromUom} → {c.ToUom} is invalid: a UOM cannot convert to itself.", 422);
+            if (c.FromUom == item.BaseUomId)
+                throw new DomainException(ErrorCodes.Validation,
+                    "The base UOM converts to itself implicitly (factor 1) and must not be listed.", 422);
+            if (c.Factor <= 0m)
+                throw new DomainException(ErrorCodes.Validation,
+                    $"Conversion {c.FromUom} → {c.ToUom} must have a factor greater than zero.", 422);
+        }
+
         foreach (var stale in item.UomConversions.Where(c => request.Conversions.All(r => r.FromUom != c.FromUomId || r.ToUom != c.ToUomId)).ToList())
             item.UomConversions.Remove(stale);
         foreach (var input in request.Conversions)

Backend/ERPCore/Services/Production/ProductionTemplateService.cs

@@ -27,6 +27,7 @@ public sealed class ProductionTemplateService : IProductionTemplateService
     private readonly IRepository<Item> _items;
     private readonly IRepository<Uom> _uoms;
     private readonly IRepository<ProductionRun> _runs;
+    private readonly IUomConverter _uomConverter;
     private readonly IUnitOfWork _uow;
     private readonly ICurrentUser _currentUser;
 
@@ -34,8 +35,9 @@ public sealed class ProductionTemplateService : IProductionTemplateService
         IRepository<ProductionTemplate> templates, IRepository<TemplateStage> stages,
         IRepository<StageInput> inputs, IRepository<StageOutput> outputs, IRepository<StageEdge> edges,
         IRepository<Item> items, IRepository<Uom> uoms, IRepository<ProductionRun> runs,
-        IUnitOfWork uow, ICurrentUser currentUser)
+        IUomConverter uomConverter, IUnitOfWork uow, ICurrentUser currentUser)
     {
+        _uomConverter = uomConverter;
         _templates = templates;
         _stages = stages;
         _inputs = inputs;
@@ -291,6 +293,20 @@ public sealed class ProductionTemplateService : IProductionTemplateService
             throw new DomainException(ErrorCodes.Validation,
                 $"UOM(s) {string.Join(", ", missingUoms)} do not exist.", 422);
 
+        // Existence is not enough: a stage line's UOM must be one its own item can convert to
+        // base, or the run would fail with a 422 at stage start — long after the template was
+        // authored. Check the (item, uom) pairing here, while the template is being saved.
+        var itemUomPairs = request.Stages
+            .SelectMany(s => s.Inputs.Select(i => (i.ItemId, i.UomId)).Concat(s.Outputs.Select(o => (o.ItemId, o.UomId))))
+            .Distinct().ToList();
+
+        foreach (var (itemId, uomId) in itemUomPairs)
+        {
+            var item = await _items.Query().AsNoTracking().FirstOrDefaultAsync(i => i.ItemId == itemId, ct);
+            if (item is not null)
+                await _uomConverter.ValidateUomAsync(item, uomId, ct);
+        }
+
         // Annotations go into jsonb unvalidated by anything else, so pin the one field the
         // client renders off. Unknown kinds would round-trip fine but draw nothing.
         var badKinds = request.Annotations

Backend/ERPCore/Services/PurchaseOrderService.cs

@@ -8,6 +8,7 @@ using ERPCore.Infra.Auth;
 using ERPCore.Infra.UoW;
 using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
 using ERPCore.System.Errors;
 using Microsoft.EntityFrameworkCore;
 
@@ -28,6 +29,7 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
     private readonly IRepository<Item> _items;
     private readonly IRepository<Uom> _uoms;
     private readonly IRepository<Warehouse> _warehouses;
+    private readonly IUomConverter _uomConverter;
     private readonly INumberSequenceService _numbers;
     private readonly ICurrentUser _currentUser;
     private readonly IUnitOfWork _uow;
@@ -35,8 +37,9 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
     public PurchaseOrderService(
         IRepository<PurchaseOrder> pos, IRepository<Vendor> vendors, IRepository<Requisition> requisitions,
         IRepository<Item> items, IRepository<Uom> uoms, IRepository<Warehouse> warehouses,
-        INumberSequenceService numbers, ICurrentUser currentUser, IUnitOfWork uow)
+        IUomConverter uomConverter, INumberSequenceService numbers, ICurrentUser currentUser, IUnitOfWork uow)
     {
+        _uomConverter = uomConverter;
         _pos = pos;
         _vendors = vendors;
         _requisitions = requisitions;
@@ -83,6 +86,7 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
     {
         await ValidateReferencesAsync(request.VendorId, request.RequisitionId, request.Lines, ct);
         var actor = _currentUser.AuditUserId;
+        var lines = await ToLinesAsync(request.Lines, ct);
 
         var po = await _uow.ExecuteInTransactionAsync(async token =>
         {
@@ -98,7 +102,7 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
                 Status = request.SaveAsDraft ? PurchaseOrderStatus.Draft : PurchaseOrderStatus.Approved,
                 CreatedBy = actor,
                 CreatedAt = DateTime.UtcNow,
-                Lines = request.Lines.Select(ToLine).ToList()
+                Lines = lines
             };
             await _pos.AddAsync(entity, token);
             return entity;
@@ -129,8 +133,8 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
 
         // Full line replacement (Phase 1: no receipts yet, so qtyReceived is 0 on every line).
         po.Lines.Clear();
-        foreach (var input in request.Lines)
-            po.Lines.Add(ToLine(input));
+        foreach (var line in await ToLinesAsync(request.Lines, ct))
+            po.Lines.Add(line);
 
         try
         {
@@ -219,16 +223,34 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
     // Supersedes Phase-1 Option B "freely editable while open" — see docs/10 FR-PROC-05.
     private static bool IsEditable(PurchaseOrderStatus status) => status is PurchaseOrderStatus.Draft;
 
-    private static PoLine ToLine(CreatePoLineInput l) => new()
+    /// <summary>
+    /// Materialises request lines, resolving each one's base quantity up front. Resolving here
+    /// rejects a UOM the item cannot be ordered in at entry time, and gives GRN receipt matching
+    /// a stable base figure to compare against regardless of the UOM the goods arrive in.
+    /// </summary>
+    private async Task<List<PoLine>> ToLinesAsync(IReadOnlyCollection<CreatePoLineInput> inputs, CancellationToken ct)
     {
-        ItemId = l.ItemId,
-        UomId = l.UomId,
-        WarehouseId = l.WarehouseId,
-        Qty = l.Qty,
-        UnitPrice = l.UnitPrice,
-        Tax = l.Tax,
-        QtyReceived = 0
-    };
+        var lines = new List<PoLine>(inputs.Count);
+        foreach (var l in inputs)
+        {
+            var item = await _items.Query().AsNoTracking().FirstAsync(i => i.ItemId == l.ItemId, ct);
+            var factor = await _uomConverter.ResolveFactorAsync(item, l.UomId, ct);
+            lines.Add(new PoLine
+            {
+                ItemId = l.ItemId,
+                UomId = l.UomId,
+                WarehouseId = l.WarehouseId,
+                Qty = l.Qty,
+                QtyBase = UomConverter.ApplyFactor(l.Qty, factor),
+                ConversionFactor = factor,
+                UnitPrice = l.UnitPrice,
+                Tax = l.Tax,
+                QtyReceived = 0,
+                QtyReceivedBase = 0
+            });
+        }
+        return lines;
+    }
 
     private static PoTotalsDto ComputeTotals(IEnumerable<PoLine> lines)
     {
@@ -276,5 +298,6 @@ public sealed class PurchaseOrderService : IPurchaseOrderService
         p.PoId, p.DocNo, p.VendorId, p.RequisitionId, p.Status, p.ApprovalRequired,
         p.CreatedBy, p.CreatedAt, p.UpdatedAt, ComputeTotals(p.Lines),
         p.Lines.OrderBy(l => l.PoLineId).Select(l => new PoLineDto(
-            l.PoLineId, l.ItemId, l.UomId, l.WarehouseId, l.Qty, l.UnitPrice, l.Tax, l.QtyReceived)).ToList());
+            l.PoLineId, l.ItemId, l.UomId, l.WarehouseId, l.Qty, l.UnitPrice, l.Tax, l.QtyReceived,
+            l.QtyBase, l.QtyReceivedBase, l.ConversionFactor)).ToList());
 }

Backend/ERPCore/Services/SalesDocumentWorkflowService.cs

@@ -0,0 +1,44 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesDocumentWorkflowService : ISalesDocumentWorkflowService
+{
+    private readonly IRepository<SalesInvoice> _invoices;
+    private readonly IRepository<SalesSlip> _slips;
+
+    public SalesDocumentWorkflowService(IRepository<SalesInvoice> invoices, IRepository<SalesSlip> slips)
+    {
+        _invoices = invoices;
+        _slips = slips;
+    }
+
+    public async Task<SalesInvoice> LoadEditableInvoiceAsync(int salesInvoiceId, uint expectedRowVersion, CancellationToken ct = default)
+    {
+        var invoice = await _invoices.Query().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesInvoiceId == salesInvoiceId, ct)
+            ?? throw new NotFoundException($"Sales invoice {salesInvoiceId} was not found.");
+        if (invoice.RowVersion != expectedRowVersion)
+            throw new DomainException(ErrorCodes.ConcurrencyConflict, "The sales invoice was modified by another request.", 412);
+        if (invoice.Status != SalesInvoiceStatus.Draft)
+            throw new ConflictException($"Sales invoice {salesInvoiceId} is {invoice.Status} and cannot be edited.");
+        return invoice;
+    }
+
+    public async Task<SalesSlip> LoadEditableSlipAsync(int salesSlipId, uint expectedRowVersion, CancellationToken ct = default)
+    {
+        var slip = await _slips.Query().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct)
+            ?? throw new NotFoundException($"Sales slip {salesSlipId} was not found.");
+        if (slip.RowVersion != expectedRowVersion)
+            throw new DomainException(ErrorCodes.ConcurrencyConflict, "The sales slip was modified by another request.", 412);
+        if (slip.Status != SalesSlipStatus.Draft)
+            throw new ConflictException($"Sales slip {salesSlipId} is {slip.Status} and cannot be edited.");
+        return slip;
+    }
+}

Backend/ERPCore/Services/SalesDomainService.cs

@@ -0,0 +1,110 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesDomainService : ISalesDomainService
+{
+    private readonly IRepository<Customer> _customers;
+    private readonly IRepository<Warehouse> _warehouses;
+    private readonly IRepository<User> _users;
+    private readonly IRepository<Item> _items;
+    private readonly IRepository<Uom> _uoms;
+    private readonly ISalesPricingService _pricing;
+
+    public SalesDomainService(
+        IRepository<Customer> customers,
+        IRepository<Warehouse> warehouses,
+        IRepository<User> users,
+        IRepository<Item> items,
+        IRepository<Uom> uoms,
+        ISalesPricingService pricing)
+    {
+        _customers = customers;
+        _warehouses = warehouses;
+        _users = users;
+        _items = items;
+        _uoms = uoms;
+        _pricing = pricing;
+    }
+
+    public async Task ValidateSalesHeaderAsync(int customerId, int warehouseId, int? cashierUserId, bool requireCashierUser, CancellationToken ct = default)
+    {
+        if (!await _customers.Query().AnyAsync(x => x.CustomerId == customerId, ct))
+            throw new NotFoundException($"Customer {customerId} was not found.");
+        if (!await _warehouses.Query().AnyAsync(x => x.WarehouseId == warehouseId, ct))
+            throw new NotFoundException($"Warehouse {warehouseId} was not found.");
+        if (requireCashierUser)
+        {
+            if (cashierUserId is null)
+                throw new DomainException(ErrorCodes.Validation, "Cashier user is required.", 422);
+            if (!await _users.Query().AnyAsync(x => x.UserId == cashierUserId, ct))
+                throw new NotFoundException($"User {cashierUserId} was not found.");
+        }
+    }
+
+    public async Task ValidateSalesLineAsync(
+        int headerWarehouseId, int lineItemId, int lineUomId, int lineWarehouseId, decimal qty, decimal freeQty, int? parentLineId, CancellationToken ct = default)
+    {
+        if (qty <= 0)
+            throw new DomainException(ErrorCodes.Validation, "Sales line quantity must be greater than zero.", 422);
+        if (freeQty < 0)
+            throw new DomainException(ErrorCodes.Validation, "Sales free quantity cannot be negative.", 422);
+        if (parentLineId is not null && parentLineId <= 0)
+            throw new DomainException(ErrorCodes.Validation, "Parent line id must be positive when supplied.", 422);
+        if (lineWarehouseId != headerWarehouseId)
+            throw new DomainException(ErrorCodes.Validation, $"Sales line warehouse {lineWarehouseId} must match header warehouse {headerWarehouseId}.", 422);
+        if (!await _items.Query().AnyAsync(x => x.ItemId == lineItemId, ct))
+            throw new NotFoundException($"Item {lineItemId} was not found.");
+        if (!await _uoms.Query().AnyAsync(x => x.UomId == lineUomId, ct))
+            throw new NotFoundException($"UOM {lineUomId} was not found.");
+        if (!await _warehouses.Query().AnyAsync(x => x.WarehouseId == lineWarehouseId, ct))
+            throw new NotFoundException($"Warehouse {lineWarehouseId} was not found.");
+    }
+
+    public Task<SalesPriceResolution> ResolveLinePriceAsync(int itemId, int warehouseId, decimal? requestedUnitPrice, bool allowManualOverride, CancellationToken ct = default)
+        => _pricing.ResolveAsync(itemId, warehouseId, requestedUnitPrice, allowManualOverride, ct);
+
+    public SalesLineComputation ComputeLine(
+        decimal qty,
+        decimal freeQty,
+        decimal unitPrice,
+        SalesDiscountMode discountMode,
+        decimal discountPct,
+        decimal discountValue,
+        decimal discountAmount,
+        decimal taxPct,
+        bool isFreeIssue)
+    {
+        var gross = qty * unitPrice;
+        var discountTotal = isFreeIssue
+            ? 0m
+            : CalculateDiscount(gross, discountMode, discountPct, discountValue, discountAmount);
+        var netUnit = qty > 0 ? (gross - discountTotal) / qty : 0m;
+        var lineTotal = gross - discountTotal;
+        var taxAmount = lineTotal * (taxPct / 100m);
+        return new SalesLineComputation(gross, discountTotal, netUnit, lineTotal, taxAmount);
+    }
+
+    public async Task<bool> IsStockedItemAsync(int itemId, CancellationToken ct = default)
+        => await _items.Query().AsNoTracking()
+            .Where(x => x.ItemId == itemId)
+            .Select(x => x.StockNature == StockNature.Stocked)
+            .FirstAsync(ct);
+
+    private static decimal CalculateDiscount(decimal gross, SalesDiscountMode mode, decimal discountPct, decimal discountValue, decimal legacyDiscountAmount)
+    {
+        var computed = mode == SalesDiscountMode.Amount
+            ? discountValue
+            : gross * (discountPct / 100m);
+
+        if (computed <= 0m && legacyDiscountAmount > 0m)
+            computed = legacyDiscountAmount;
+
+        return Math.Min(gross, Math.Max(0m, computed));
+    }
+}

Backend/ERPCore/Services/SalesInvoiceService.cs

@@ -0,0 +1,206 @@
+using ERPCore.Common.Http;
+using ERPCore.Domain;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Infra.Auth;
+using ERPCore.Infra.UoW;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesInvoiceService : ISalesInvoiceService
+{
+    private readonly IRepository<SalesInvoice> _invoices;
+    private readonly IRepository<Customer> _customers;
+    private readonly IRepository<Item> _items;
+    private readonly IRepository<Uom> _uoms;
+    private readonly IRepository<Warehouse> _warehouses;
+    private readonly ISalesDomainService _sales;
+    private readonly ISalesPostingService _posting;
+    private readonly ISalesMappingService _mapping;
+    private readonly ISalesDocumentWorkflowService _workflow;
+    private readonly IUomConverter _uomConverter;
+    private readonly ICurrentUser _currentUser;
+    private readonly INumberSequenceService _numbers;
+    private readonly IUnitOfWork _uow;
+
+    public SalesInvoiceService(
+        IRepository<SalesInvoice> invoices, IRepository<Customer> customers, IRepository<Item> items,
+        IRepository<Uom> uoms, IRepository<Warehouse> warehouses, ISalesDomainService sales, ISalesPostingService posting, ISalesMappingService mapping,
+        ISalesDocumentWorkflowService workflow, IUomConverter uomConverter,
+        ICurrentUser currentUser, INumberSequenceService numbers, IUnitOfWork uow)
+    {
+        _uomConverter = uomConverter;
+        _invoices = invoices;
+        _customers = customers;
+        _items = items;
+        _uoms = uoms;
+        _warehouses = warehouses;
+        _sales = sales;
+        _posting = posting;
+        _mapping = mapping;
+        _workflow = workflow;
+        _currentUser = currentUser;
+        _numbers = numbers;
+        _uow = uow;
+    }
+
+    public async Task<PagedResponse<SalesInvoiceSummaryDto>> ListAsync(PageQuery query, SalesInvoiceStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default)
+    {
+        IQueryable<SalesInvoice> q = _invoices.Query().AsNoTracking().Include(x => x.Lines);
+        if (!string.IsNullOrWhiteSpace(query.Q))
+        {
+            var term = query.Q.Trim();
+            q = q.Where(x => EF.Functions.ILike(x.InvoiceNo, $"%{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.SalesInvoiceId).Skip(query.Skip).Take(query.PageSize).ToListAsync(ct);
+
+        return PagedResponse<SalesInvoiceSummaryDto>.Create(rows.Select(MapSummary).ToList(), query.Page, query.PageSize, total);
+    }
+
+    public async Task<ETagged<SalesInvoiceDto>?> GetAsync(int salesInvoiceId, CancellationToken ct = default)
+    {
+        var invoice = await _invoices.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesInvoiceId == salesInvoiceId, ct);
+        return invoice is null ? null : new ETagged<SalesInvoiceDto>(_mapping.MapInvoice(invoice), invoice.RowVersion);
+    }
+
+    public Task<SalesInvoicePostingCheckDto> CheckPostingAsync(int salesInvoiceId, CancellationToken ct = default)
+        => _posting.CheckInvoiceAsync(salesInvoiceId, ct);
+
+    public async Task<ETagged<SalesInvoiceDto>> CreateAsync(CreateSalesInvoiceRequest request, CancellationToken ct = default)
+    {
+        await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, null, false, ct);
+        var invoice = new SalesInvoice
+        {
+            InvoiceNo = await _numbers.NextAsync(DocumentTypes.SalesInvoice, ct),
+            InvoiceDate = DateTime.UtcNow,
+            CustomerId = request.CustomerId,
+            WarehouseId = request.WarehouseId,
+            InvoiceType = request.InvoiceType,
+            Status = SalesInvoiceStatus.Draft,
+            CreatedBy = _currentUser.AuditUserId,
+            CreatedAt = DateTime.UtcNow
+        };
+        invoice.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
+        invoice.CustomerSnapshotTaxNo = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.TaxRegistrationNo).FirstAsync(ct);
+        invoice.Lines = await BuildLinesAsync(request.WarehouseId, request.Lines, ct);
+        Recalculate(invoice);
+
+        await _invoices.AddAsync(invoice, ct);
+        await _uow.SaveChangesAsync(ct);
+        return new ETagged<SalesInvoiceDto>(_mapping.MapInvoice(invoice), invoice.RowVersion);
+    }
+
+    public async Task<ETagged<SalesInvoiceDto>> UpdateAsync(int salesInvoiceId, UpdateSalesInvoiceRequest request, uint expectedRowVersion, CancellationToken ct = default)
+    {
+        var invoice = await _workflow.LoadEditableInvoiceAsync(salesInvoiceId, expectedRowVersion, ct);
+
+        await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, null, false, ct);
+        invoice.CustomerId = request.CustomerId;
+        invoice.WarehouseId = request.WarehouseId;
+        invoice.InvoiceType = request.InvoiceType;
+        invoice.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
+        invoice.CustomerSnapshotTaxNo = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.TaxRegistrationNo).FirstAsync(ct);
+        invoice.Lines.Clear();
+        foreach (var line in await BuildLinesAsync(request.WarehouseId, request.Lines, ct)) invoice.Lines.Add(line);
+        Recalculate(invoice);
+        invoice.UpdatedAt = DateTime.UtcNow;
+        await _uow.SaveChangesAsync(ct);
+        return new ETagged<SalesInvoiceDto>(_mapping.MapInvoice(invoice), invoice.RowVersion);
+    }
+
+    public async Task<SalesInvoiceDto> PostAsync(int salesInvoiceId, CancellationToken ct = default)
+        {
+            await _posting.PostInvoiceAsync(salesInvoiceId, ct);
+            var invoice = await _invoices.Query().AsNoTracking().Include(x => x.Lines)
+                .FirstAsync(x => x.SalesInvoiceId == salesInvoiceId, ct);
+            return _mapping.MapInvoice(invoice);
+        }
+
+    public async Task<SalesInvoiceDto> CancelAsync(int salesInvoiceId, CancellationToken ct = default)
+    {
+        var invoice = await _invoices.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.SalesInvoiceId == salesInvoiceId, ct)
+            ?? throw new NotFoundException($"Sales invoice {salesInvoiceId} was not found.");
+        if (invoice.Status != SalesInvoiceStatus.Draft)
+            throw new ConflictException($"Sales invoice {salesInvoiceId} is {invoice.Status} and cannot be cancelled.");
+        invoice.Status = SalesInvoiceStatus.Cancelled;
+        invoice.UpdatedAt = DateTime.UtcNow;
+        await _uow.SaveChangesAsync(ct);
+        return _mapping.MapInvoice(invoice);
+    }
+
+    private async Task<List<SalesInvoiceLine>> BuildLinesAsync(int headerWarehouseId, List<CreateSalesInvoiceLineRequest> requests, CancellationToken ct)
+    {
+        var lines = new List<SalesInvoiceLine>();
+        foreach (var r in requests)
+        {
+            var item = await _items.Query().AsNoTracking().FirstAsync(x => x.ItemId == r.ItemId, ct);
+            await _sales.ValidateSalesLineAsync(headerWarehouseId, r.ItemId, r.UomId, r.WarehouseId, r.Qty, r.FreeQty, r.ParentLineId, ct);
+            var resolved = await _sales.ResolveLinePriceAsync(r.ItemId, r.WarehouseId, r.UnitPrice, r.AllowManualPriceOverride, ct);
+            var unitPrice = resolved.UnitPrice;
+            var priceSource = resolved.PriceSource;
+
+            var calc = _sales.ComputeLine(r.Qty, r.FreeQty, unitPrice, r.DiscountMode, r.DiscountPct, r.DiscountValue, r.DiscountAmount, r.TaxPct, r.IsFreeIssue);
+
+            // Resolve the base quantity now and store it on the line. This doubles as the
+            // entry-time UOM check (an item that cannot be sold in this UOM throws 422 here,
+            // while the user is still editing) and as the snapshot posting consumes — a
+            // conversion factor edited later must not change what this document posts.
+            var factor = await _uomConverter.ResolveFactorAsync(item, r.UomId, ct);
+
+            lines.Add(new SalesInvoiceLine
+            {
+                ItemId = r.ItemId,
+                Description = item.Name,
+                Qty = r.Qty,
+                FreeQty = r.FreeQty,
+                UomId = r.UomId,
+                QtyBase = UomConverter.ApplyFactor(r.Qty, factor),
+                FreeQtyBase = UomConverter.ApplyFactor(r.FreeQty, factor),
+                ConversionFactor = factor,
+                WarehouseId = r.WarehouseId,
+                UnitPrice = unitPrice,
+                BaseCost = unitPrice,
+                PriceSource = priceSource,
+                DiscountPct = r.DiscountPct,
+                DiscountAmount = calc.DiscountTotal,
+                DiscountMode = r.DiscountMode,
+                NetUnitPrice = calc.NetUnitPrice,
+                LineTotal = calc.LineTotal,
+                TaxPct = r.TaxPct,
+                TaxAmount = calc.TaxAmount,
+                IsFreeIssue = r.IsFreeIssue,
+                ParentLineId = r.ParentLineId
+            });
+        }
+        return lines;
+    }
+
+    private static void Recalculate(SalesInvoice invoice)
+    {
+        invoice.Subtotal = invoice.Lines.Sum(x => x.Qty * x.UnitPrice);
+        invoice.DiscountTotal = invoice.Lines.Sum(x => x.DiscountAmount);
+        invoice.TaxTotal = invoice.Lines.Sum(x => x.TaxAmount);
+        invoice.GrandTotal = invoice.Lines.Sum(x => x.LineTotal) + invoice.TaxTotal;
+        invoice.RoundOff = 0m;
+        invoice.NetPayable = invoice.GrandTotal + invoice.RoundOff;
+        invoice.PaidAmount = 0m;
+        invoice.BalanceAmount = invoice.NetPayable;
+    }
+
+    private SalesInvoiceSummaryDto MapSummary(SalesInvoice x) => new(
+        x.SalesInvoiceId, x.InvoiceNo, x.InvoiceDate, x.CustomerId, x.CustomerSnapshotName,
+        x.WarehouseId, x.InvoiceType, x.Status, _mapping.MapInvoiceTotals(x), x.CreatedAt);
+}

Backend/ERPCore/Services/SalesMappingService.cs

@@ -0,0 +1,51 @@
+using ERPCore.Domain.Entities;
+using ERPCore.Dtos.Sales;
+using ERPCore.Services.Interfaces;
+
+namespace ERPCore.Services;
+
+public sealed class SalesMappingService : ISalesMappingService
+{
+    public SalesInvoiceTotalsDto MapInvoiceTotals(SalesInvoice invoice)
+        => new(
+            invoice.Subtotal,
+            invoice.DiscountTotal,
+            invoice.Lines.Sum(l => l.FreeQty),
+            invoice.TaxTotal,
+            invoice.GrandTotal,
+            invoice.RoundOff,
+            invoice.NetPayable,
+            invoice.PaidAmount,
+            invoice.BalanceAmount);
+
+    public SalesSlipTotalsDto MapSlipTotals(SalesSlip slip)
+        => new(
+            slip.Subtotal,
+            slip.DiscountTotal,
+            slip.Lines.Sum(l => l.FreeQty),
+            slip.TaxTotal,
+            slip.GrandTotal,
+            slip.PaidAmount,
+            slip.BalanceAmount);
+
+    public SalesInvoiceDto MapInvoice(SalesInvoice invoice)
+        => new(
+            invoice.SalesInvoiceId, invoice.InvoiceNo, invoice.InvoiceDate, invoice.CustomerId,
+            invoice.CustomerSnapshotName, invoice.CustomerSnapshotTaxNo, invoice.WarehouseId,
+            invoice.InvoiceType, invoice.Status, invoice.CreatedBy, invoice.CreatedAt, invoice.UpdatedAt,
+            MapInvoiceTotals(invoice),
+            invoice.Lines.Select(l => new SalesInvoiceLineDto(
+                l.SalesInvoiceLineId, 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());
+
+    public SalesSlipDto MapSlip(SalesSlip slip)
+        => new(
+            slip.SalesSlipId, slip.SlipNo, slip.SlipDate, slip.CustomerId, slip.CustomerSnapshotName,
+            slip.WarehouseId, slip.CashierUserId, slip.Status, slip.CreatedAt, slip.UpdatedAt,
+            MapSlipTotals(slip),
+            slip.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());
+}

Backend/ERPCore/Services/SalesPostingService.cs

@@ -0,0 +1,227 @@
+using ERPCore.Domain;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Sales;
+using ERPCore.Infra.Auth;
+using ERPCore.Infra.UoW;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesPostingService : ISalesPostingService
+{
+    private readonly IRepository<SalesInvoice> _invoices;
+    private readonly IRepository<SalesSlip> _slips;
+    private readonly IRepository<BundleSale> _bundles;
+    private readonly IRepository<Item> _items;
+    private readonly IFifoCostingService _fifo;
+    private readonly ISalesDomainService _sales;
+    private readonly ICurrentUser _currentUser;
+    private readonly IUnitOfWork _uow;
+
+    // No IUomConverter here by design: every line arrives with its base quantity already
+    // snapshotted by the service that saved it, so posting has nothing left to convert.
+    public SalesPostingService(
+        IRepository<SalesInvoice> invoices,
+        IRepository<SalesSlip> slips,
+        IRepository<BundleSale> bundles,
+        IRepository<Item> items,
+        IFifoCostingService fifo,
+        ISalesDomainService sales,
+        ICurrentUser currentUser,
+        IUnitOfWork uow)
+    {
+        _invoices = invoices;
+        _slips = slips;
+        _bundles = bundles;
+        _items = items;
+        _fifo = fifo;
+        _sales = sales;
+        _currentUser = currentUser;
+        _uow = uow;
+    }
+
+    public async Task<SalesInvoicePostingCheckDto> CheckInvoiceAsync(int salesInvoiceId, CancellationToken ct = default)
+    {
+        var invoice = await _invoices.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesInvoiceId == salesInvoiceId, ct)
+            ?? throw new NotFoundException($"Sales invoice {salesInvoiceId} was not found.");
+
+        if (invoice.Status != SalesInvoiceStatus.Draft)
+            return new SalesInvoicePostingCheckDto(invoice.SalesInvoiceId, invoice.InvoiceNo, invoice.Status, false, Array.Empty<SalesInvoicePostingIssueDto>());
+
+        var issues = new List<SalesInvoicePostingIssueDto>();
+        foreach (var line in invoice.Lines)
+        {
+            if (!await _sales.IsStockedItemAsync(line.ItemId, ct))
+                continue;
+            // Compare base against base: on-hand is base UOM, so the entered quantity would
+            // under-report the requirement on any line not in the item's base UOM.
+            var requestedQty = line.QtyBase + line.FreeQtyBase;
+            var available = await _fifo.GetOnHandAsync(line.ItemId, line.WarehouseId, ct);
+            if (available >= requestedQty) continue;
+
+            var item = await _items.Query().AsNoTracking()
+                .Where(x => x.ItemId == line.ItemId)
+                .Select(x => new { x.Sku, x.Name, BaseUomName = x.BaseUom!.Name })
+                .FirstAsync(ct);
+
+            issues.Add(new SalesInvoicePostingIssueDto(
+                line.SalesInvoiceLineId, line.ItemId, item.Sku, item.Name, line.WarehouseId,
+                requestedQty, available, requestedQty - available, line.IsFreeIssue, item.BaseUomName));
+        }
+
+        return new SalesInvoicePostingCheckDto(invoice.SalesInvoiceId, invoice.InvoiceNo, invoice.Status, issues.Count == 0, issues);
+    }
+
+    public async Task<SalesSlipPostingCheckDto> CheckSlipAsync(int salesSlipId, CancellationToken ct = default)
+    {
+        var slip = await _slips.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct)
+            ?? throw new NotFoundException($"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)
+        {
+            if (!await _sales.IsStockedItemAsync(line.ItemId, ct))
+                continue;
+            // Base against base — see the matching comment in CheckInvoiceAsync.
+            var requestedQty = line.QtyBase + line.FreeQtyBase;
+            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, BaseUomName = x.BaseUom!.Name })
+                .FirstAsync(ct);
+
+            issues.Add(new SalesSlipPostingIssueDto(
+                line.SalesSlipLineId, line.ItemId, item.Sku, item.Name, line.WarehouseId,
+                requestedQty, available, requestedQty - available, line.IsFreeIssue, item.BaseUomName));
+        }
+
+        return new SalesSlipPostingCheckDto(slip.SalesSlipId, slip.SlipNo, slip.Status, issues.Count == 0, issues);
+    }
+
+    public async Task<BundleSalePostingCheckDto> CheckBundleAsync(int bundleSaleId, CancellationToken ct = default)
+    {
+        var bundle = await _bundles.Query().AsNoTracking().Include(x => x.Lines)
+            .FirstOrDefaultAsync(x => x.BundleSaleId == bundleSaleId, ct)
+            ?? throw new NotFoundException($"Bundle sale {bundleSaleId} was not found.");
+
+        if (bundle.Status != BundleSaleStatus.Draft)
+            return new BundleSalePostingCheckDto(bundle.BundleSaleId, bundle.BundleNo, bundle.Status, false, Array.Empty<BundleSalePostingIssueDto>());
+
+        var issues = new List<BundleSalePostingIssueDto>();
+        foreach (var line in bundle.Lines.Where(l => l.IncludeInBundle))
+        {
+            if (!await _sales.IsStockedItemAsync(line.ItemId, ct))
+                continue;
+
+            var item = await _items.Query().AsNoTracking()
+                .Where(x => x.ItemId == line.ItemId)
+                .Select(x => new { x.Sku, x.Name, BaseUomName = x.BaseUom!.Name })
+                .FirstAsync(ct);
+            var available = await _fifo.GetOnHandAsync(line.ItemId, line.WarehouseId, ct);
+            if (available >= line.QtyBase) continue;
+
+            issues.Add(new BundleSalePostingIssueDto(
+                line.BundleSaleLineId, line.ItemId, item.Sku, item.Name, line.WarehouseId,
+                line.QtyBase, available, line.QtyBase - available, item.BaseUomName));
+        }
+
+        return new BundleSalePostingCheckDto(bundle.BundleSaleId, bundle.BundleNo, bundle.Status, issues.Count == 0, issues);
+    }
+
+    public Task PostInvoiceAsync(int salesInvoiceId, CancellationToken ct = default)
+        => PostAsync(
+            load: () => _invoices.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.SalesInvoiceId == salesInvoiceId, ct),
+            notFoundMessage: $"Sales invoice {salesInvoiceId} was not found.",
+            statusSelector: x => x.Status,
+            ensureDraftMessage: x => $"Sales invoice {x.SalesInvoiceId} is {x.Status} and cannot be posted.",
+            getLines: x => x.Lines.Select(l => new PostingLine(l.ItemId, l.WarehouseId, l.QtyBase + l.FreeQtyBase, l.QtyBase, l.FreeQtyBase)),
+            setPosted: x => x.Status = SalesInvoiceStatus.Posted,
+            setUpdated: x => x.UpdatedAt = DateTime.UtcNow,
+            sourceDocType: DocumentTypes.SalesInvoice,
+            getDocId: x => x.SalesInvoiceId,
+            ct: ct);
+
+    public Task PostSlipAsync(int salesSlipId, CancellationToken ct = default)
+        => PostAsync(
+            load: () => _slips.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct),
+            notFoundMessage: $"Sales slip {salesSlipId} was not found.",
+            statusSelector: x => x.Status,
+            ensureDraftMessage: x => $"Sales slip {x.SalesSlipId} is {x.Status} and cannot be posted.",
+            getLines: x => x.Lines.Select(l => new PostingLine(l.ItemId, l.WarehouseId, l.QtyBase + l.FreeQtyBase, l.QtyBase, l.FreeQtyBase)),
+            setPosted: x => x.Status = SalesSlipStatus.Posted,
+            setUpdated: x => x.UpdatedAt = DateTime.UtcNow,
+            sourceDocType: DocumentTypes.SalesSlip,
+            getDocId: x => x.SalesSlipId,
+            ct: ct);
+
+    public Task PostBundleAsync(int bundleSaleId, CancellationToken ct = default)
+        => PostAsync(
+            load: () => _bundles.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.BundleSaleId == bundleSaleId, ct),
+            notFoundMessage: $"Bundle sale {bundleSaleId} was not found.",
+            statusSelector: x => x.Status,
+            ensureDraftMessage: x => $"Bundle sale {x.BundleSaleId} is {x.Status} and cannot be posted.",
+            getLines: x => x.Lines.Where(l => l.IncludeInBundle).Select(l => new PostingLine(l.ItemId, l.WarehouseId, l.QtyBase, l.QtyBase, 0m)),
+            setPosted: x => x.Status = BundleSaleStatus.Posted,
+            setUpdated: x => x.UpdatedAt = DateTime.UtcNow,
+            sourceDocType: DocumentTypes.BundleSale,
+            getDocId: x => x.BundleSaleId,
+            ct: ct);
+
+    private async Task PostAsync<T>(
+        Func<Task<T?>> load,
+        string notFoundMessage,
+        Func<T, object> statusSelector,
+        Func<T, string> ensureDraftMessage,
+        Func<T, IEnumerable<PostingLine>> getLines,
+        Action<T> setPosted,
+        Action<T> setUpdated,
+        string sourceDocType,
+        Func<T, int> getDocId,
+        CancellationToken ct)
+        where T : class
+    {
+        var doc = await load() ?? throw new NotFoundException(notFoundMessage);
+        var status = statusSelector(doc);
+        var statusValue = status?.ToString() ?? string.Empty;
+        if (!string.Equals(statusValue, "Draft", StringComparison.Ordinal))
+            throw new ConflictException(ensureDraftMessage(doc));
+
+        await _uow.ExecuteInTransactionAsync(async token =>
+        {
+            foreach (var line in getLines(doc))
+            {
+                if (line.Qty <= 0) continue;
+                if (!await _sales.IsStockedItemAsync(line.ItemId, token))
+                    continue;
+
+                var consumed = await _fifo.ConsumeAsync(line.ItemId, line.WarehouseId, null, line.Qty, token);
+                var cost = consumed.Count == 0 ? 0m : consumed.Sum(x => x.Qty * x.UnitCost) / consumed.Sum(x => x.Qty);
+                await _fifo.PostLedgerAsync(line.ItemId, line.WarehouseId, null, null, null, _currentUser.AuditUserId,
+                    Direction.Out, line.Qty, cost, 0m, sourceDocType, getDocId(doc), DateTime.UtcNow, token);
+            }
+
+            setPosted(doc);
+            setUpdated(doc);
+        }, ct);
+    }
+
+    /// <summary>
+    /// A line reduced to what posting needs. Every quantity here is in the item's <b>base</b>
+    /// UOM, taken from the snapshot the document service resolved at save — the FIFO engine
+    /// accepts nothing else, and re-resolving at post time would let a factor edited in the
+    /// meantime change what a saved document consumes.
+    /// </summary>
+    private sealed record PostingLine(int ItemId, int WarehouseId, decimal Qty, decimal PaidQty, decimal FreeQty);
+}

Backend/ERPCore/Services/SalesPricingService.cs

@@ -0,0 +1,79 @@
+using ERPCore.Domain;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesPricingService : ISalesPricingService
+{
+    private readonly IRepository<Item> _items;
+    private readonly IRepository<GrnLine> _grnLines;
+    private readonly IFifoCostingService _fifo;
+
+    public SalesPricingService(IRepository<Item> items, IRepository<GrnLine> grnLines, IFifoCostingService fifo)
+    {
+        _items = items;
+        _grnLines = grnLines;
+        _fifo = fifo;
+    }
+
+    public async Task<SalesPriceResolution> ResolveAsync(
+        int itemId, int warehouseId, decimal? requestedUnitPrice, bool allowManualOverride, CancellationToken ct = default)
+    {
+        var item = await _items.Query().AsNoTracking().FirstOrDefaultAsync(x => x.ItemId == itemId, ct)
+            ?? throw new InvalidOperationException($"Item {itemId} was not found.");
+
+        if (requestedUnitPrice is not null)
+        {
+            if (!allowManualOverride)
+            {
+                if (item.SalePrice.HasValue)
+                    return new SalesPriceResolution(item.SalePrice.Value, "SALE_PRICE", item.SalePrice.Value);
+
+                var grnPrice = await GetWeightedGrnPriceAsync(itemId, warehouseId, ct);
+                if (grnPrice is not null)
+                    return new SalesPriceResolution(grnPrice.Value, "GRN_WEIGHTED_AVG", grnPrice.Value);
+
+                return new SalesPriceResolution(await GetFifoFallbackPriceAsync(itemId, warehouseId, ct), "FIFO_AVG", 0m);
+            }
+
+            return new SalesPriceResolution(requestedUnitPrice.Value, "MANUAL", requestedUnitPrice.Value);
+        }
+
+        if (item.SalePrice.HasValue)
+            return new SalesPriceResolution(item.SalePrice.Value, "SALE_PRICE", item.SalePrice.Value);
+
+        var weighted = await GetWeightedGrnPriceAsync(itemId, warehouseId, ct);
+        if (weighted is not null)
+            return new SalesPriceResolution(weighted.Value, "GRN_WEIGHTED_AVG", weighted.Value);
+
+        return new SalesPriceResolution(await GetFifoFallbackPriceAsync(itemId, warehouseId, ct), "FIFO_AVG", 0m);
+    }
+
+    private async Task<decimal?> GetWeightedGrnPriceAsync(int itemId, int warehouseId, CancellationToken ct)
+    {
+        var rows = await _grnLines.Query().AsNoTracking()
+            .Where(l => l.ItemId == itemId
+                        && l.Grn != null
+                        && l.Grn.WarehouseId == warehouseId
+                        && l.Grn.Status == GrnStatus.Confirmed)
+            .Select(l => new { l.Qty, l.ReceivedValue })
+            .ToListAsync(ct);
+
+        var totalQty = rows.Sum(x => x.Qty);
+        if (totalQty <= 0) return null;
+
+        var totalValue = rows.Sum(x => x.ReceivedValue);
+        return totalValue / totalQty;
+    }
+
+    private async Task<decimal> GetFifoFallbackPriceAsync(int itemId, int warehouseId, CancellationToken ct)
+    {
+        var valuation = await _fifo.GetValuationAsync(itemId, warehouseId, ct);
+        return valuation.TotalQty > 0 ? valuation.TotalValue / valuation.TotalQty : 0m;
+    }
+}

Backend/ERPCore/Services/SalesPromotionSuggestionService.cs

@@ -0,0 +1,76 @@
+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 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 freeIssueLines = slip.Lines
+            .Where(x => x.IsFreeIssue || x.FreeQty > 0m)
+            .ToList();
+
+        if (freeIssueLines.Count == 0)
+            return new SalesFreeIssueSuggestionDto(slip.SalesSlipId, slip.SlipNo, slip.SlipDate, Array.Empty<SalesFreeIssueSuggestionLineDto>());
+
+        var itemIds = freeIssueLines.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 freeIssueLines)
+        {
+            if (!byItemId.TryGetValue(line.ItemId, out var item)) 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,
+                line.FreeQty,
+                line.Qty,
+                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

@@ -0,0 +1,362 @@
+using ERPCore.Domain.Entities;
+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;
+
+    public SalesReportService(IRepository<SalesInvoice> invoices, IRepository<SalesSlip> slips)
+    {
+        _invoices = invoices;
+        _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()
+            .Where(x => x.Status == SalesInvoiceStatus.Posted && x.InvoiceDate >= from.ToDateTime(TimeOnly.MinValue) && x.InvoiceDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue))
+            .GroupBy(x => DateOnly.FromDateTime(x.InvoiceDate))
+            .Select(g => new
+            {
+                Date = g.Key,
+                InvoiceCount = g.Count(),
+                SlipCount = 0,
+                InvoiceSubtotal = g.Sum(x => x.Subtotal),
+                SlipSubtotal = 0m,
+                DiscountTotal = g.Sum(x => x.DiscountTotal),
+                FreeQtyTotal = g.Sum(x => x.Lines.Sum(l => l.FreeQty)),
+                TaxTotal = g.Sum(x => x.TaxTotal),
+                GrandTotal = g.Sum(x => x.GrandTotal)
+            })
+            .ToListAsync(ct);
+
+        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))
+            .GroupBy(x => DateOnly.FromDateTime(x.SlipDate))
+            .Select(g => new
+            {
+                Date = g.Key,
+                InvoiceCount = 0,
+                SlipCount = g.Count(),
+                InvoiceSubtotal = 0m,
+                SlipSubtotal = g.Sum(x => x.Subtotal),
+                DiscountTotal = g.Sum(x => x.DiscountTotal),
+                FreeQtyTotal = g.Sum(x => x.Lines.Sum(l => l.FreeQty)),
+                TaxTotal = g.Sum(x => x.TaxTotal),
+                GrandTotal = g.Sum(x => x.GrandTotal)
+            })
+            .ToListAsync(ct);
+
+        return invoiceRows.Concat(slipRows)
+            .GroupBy(x => x.Date)
+            .OrderBy(x => x.Key)
+            .Select(g => new SalesDailySummaryRowDto(
+                g.Key,
+                g.Sum(x => x.InvoiceCount),
+                g.Sum(x => x.SlipCount),
+                g.Sum(x => x.InvoiceSubtotal),
+                g.Sum(x => x.SlipSubtotal),
+                g.Sum(x => x.DiscountTotal),
+                g.Sum(x => x.FreeQtyTotal),
+                g.Sum(x => x.TaxTotal),
+                g.Sum(x => x.GrandTotal)))
+            .ToList();
+    }
+
+    public async Task<IReadOnlyList<SalesItemSummaryRowDto>> ItemSummaryAsync(DateOnly from, DateOnly to, int? itemId, int? warehouseId, CancellationToken ct = default)
+    {
+        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);
+
+        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 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,
+                g.Sum(x => x.Qty),
+                g.Sum(x => x.FreeQty),
+                g.Sum(x => x.Gross),
+                g.Sum(x => x.DiscountAmount),
+                g.Sum(x => x.TaxAmount),
+                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)
+    {
+        var invoiceQuery = _invoices.Query().AsNoTracking()
+            .Where(x => x.Status == SalesInvoiceStatus.Posted && x.InvoiceDate >= from.ToDateTime(TimeOnly.MinValue) && x.InvoiceDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue));
+        if (customerId is not null) invoiceQuery = invoiceQuery.Where(x => x.CustomerId == customerId);
+
+        var slipQuery = _slips.Query().AsNoTracking()
+            .Where(x => x.Status == SalesSlipStatus.Posted && x.SlipDate >= from.ToDateTime(TimeOnly.MinValue) && x.SlipDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue));
+        if (customerId is not null) slipQuery = slipQuery.Where(x => x.CustomerId == customerId);
+
+        var invoiceRows = await invoiceQuery
+            .GroupBy(x => new { x.CustomerId, x.CustomerSnapshotName })
+            .Select(g => new
+            {
+                g.Key.CustomerId,
+                CustomerName = g.Key.CustomerSnapshotName,
+                InvoiceCount = g.Count(),
+                SlipCount = 0,
+                SoldQty = g.Sum(x => x.Lines.Sum(l => l.Qty)),
+                FreeQty = g.Sum(x => x.Lines.Sum(l => l.FreeQty)),
+                GrossAmount = g.Sum(x => x.Subtotal),
+                DiscountTotal = g.Sum(x => x.DiscountTotal),
+                TaxTotal = g.Sum(x => x.TaxTotal),
+                NetAmount = g.Sum(x => x.GrandTotal)
+            })
+            .ToListAsync(ct);
+
+        var slipRows = await slipQuery
+            .GroupBy(x => new { x.CustomerId, x.CustomerSnapshotName })
+            .Select(g => new
+            {
+                g.Key.CustomerId,
+                CustomerName = g.Key.CustomerSnapshotName,
+                InvoiceCount = 0,
+                SlipCount = g.Count(),
+                SoldQty = g.Sum(x => x.Lines.Sum(l => l.Qty)),
+                FreeQty = g.Sum(x => x.Lines.Sum(l => l.FreeQty)),
+                GrossAmount = g.Sum(x => x.Subtotal),
+                DiscountTotal = g.Sum(x => x.DiscountTotal),
+                TaxTotal = g.Sum(x => x.TaxTotal),
+                NetAmount = g.Sum(x => x.GrandTotal)
+            })
+            .ToListAsync(ct);
+
+        return invoiceRows.Concat(slipRows)
+            .GroupBy(x => new { x.CustomerId, x.CustomerName })
+            .OrderByDescending(g => g.Sum(x => x.NetAmount))
+            .Select(g => new SalesCustomerSummaryRowDto(
+                g.Key.CustomerId,
+                g.Key.CustomerName,
+                g.Sum(x => x.InvoiceCount),
+                g.Sum(x => x.SlipCount),
+                g.Sum(x => x.SoldQty),
+                g.Sum(x => x.FreeQty),
+                g.Sum(x => x.GrossAmount),
+                g.Sum(x => x.DiscountTotal),
+                g.Sum(x => x.TaxTotal),
+                g.Sum(x => x.NetAmount)))
+            .ToList();
+    }
+
+    public async Task<IReadOnlyList<SalesWarehouseSummaryRowDto>> WarehouseSummaryAsync(DateOnly from, DateOnly to, int? warehouseId, CancellationToken ct = default)
+    {
+        var invoiceQuery = _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) invoiceQuery = invoiceQuery.Where(x => x.WarehouseId == warehouseId);
+
+        var slipQuery = _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) slipQuery = slipQuery.Where(x => x.WarehouseId == warehouseId);
+
+        var invoiceRows = await invoiceQuery
+            .GroupBy(x => new { x.WarehouseId, x.Warehouse!.Name })
+            .Select(g => new
+            {
+                g.Key.WarehouseId,
+                WarehouseName = g.Key.Name,
+                InvoiceCount = g.Count(),
+                SlipCount = 0,
+                SoldQty = g.Sum(x => x.Lines.Sum(l => l.Qty)),
+                FreeQty = g.Sum(x => x.Lines.Sum(l => l.FreeQty)),
+                GrossAmount = g.Sum(x => x.Subtotal),
+                DiscountTotal = g.Sum(x => x.DiscountTotal),
+                TaxTotal = g.Sum(x => x.TaxTotal),
+                NetAmount = g.Sum(x => x.GrandTotal)
+            })
+            .ToListAsync(ct);
+
+        var slipRows = await slipQuery
+            .GroupBy(x => new { x.WarehouseId, x.Warehouse!.Name })
+            .Select(g => new
+            {
+                g.Key.WarehouseId,
+                WarehouseName = g.Key.Name,
+                InvoiceCount = 0,
+                SlipCount = g.Count(),
+                SoldQty = g.Sum(x => x.Lines.Sum(l => l.Qty)),
+                FreeQty = g.Sum(x => x.Lines.Sum(l => l.FreeQty)),
+                GrossAmount = g.Sum(x => x.Subtotal),
+                DiscountTotal = g.Sum(x => x.DiscountTotal),
+                TaxTotal = g.Sum(x => x.TaxTotal),
+                NetAmount = g.Sum(x => x.GrandTotal)
+            })
+            .ToListAsync(ct);
+
+        return invoiceRows.Concat(slipRows)
+            .GroupBy(x => new { x.WarehouseId, x.WarehouseName })
+            .OrderByDescending(g => g.Sum(x => x.NetAmount))
+            .Select(g => new SalesWarehouseSummaryRowDto(
+                g.Key.WarehouseId,
+                g.Key.WarehouseName,
+                g.Sum(x => x.InvoiceCount),
+                g.Sum(x => x.SlipCount),
+                g.Sum(x => x.SoldQty),
+                g.Sum(x => x.FreeQty),
+                g.Sum(x => x.GrossAmount),
+                g.Sum(x => x.DiscountTotal),
+                g.Sum(x => x.TaxTotal),
+                g.Sum(x => x.NetAmount)))
+            .ToList();
+    }
+
+    public async Task<IReadOnlyList<SalesDiscountSummaryRowDto>> DiscountSummaryAsync(DateOnly from, DateOnly to, CancellationToken ct = default)
+    {
+        var invoices = await _invoices.Query().AsNoTracking()
+            .Where(x => x.Status == SalesInvoiceStatus.Posted && x.InvoiceDate >= from.ToDateTime(TimeOnly.MinValue) && x.InvoiceDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue) && x.DiscountTotal > 0m)
+            .Select(x => new SalesDiscountSummaryRowDto("Invoice", x.InvoiceNo, x.InvoiceDate, x.CustomerSnapshotName, x.Subtotal, x.DiscountTotal, x.TaxTotal, x.GrandTotal))
+            .ToListAsync(ct);
+
+        var slips = await _slips.Query().AsNoTracking()
+            .Where(x => x.Status == SalesSlipStatus.Posted && x.SlipDate >= from.ToDateTime(TimeOnly.MinValue) && x.SlipDate < to.AddDays(1).ToDateTime(TimeOnly.MinValue) && x.DiscountTotal > 0m)
+            .Select(x => new SalesDiscountSummaryRowDto("Slip", x.SlipNo, x.SlipDate, x.CustomerSnapshotName, x.Subtotal, x.DiscountTotal, x.TaxTotal, x.GrandTotal))
+            .ToListAsync(ct);
+
+        return invoices.Concat(slips).OrderByDescending(x => x.DiscountTotal).ToList();
+    }
+
+    public async Task<IReadOnlyList<SalesFreeIssueSummaryRowDto>> FreeIssueSummaryAsync(DateOnly from, DateOnly to, CancellationToken ct = default)
+    {
+        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.Where(l => l.FreeQty > 0m).Select(l => new SalesFreeIssueSummaryRowDto(
+                "Invoice",
+                x.InvoiceNo,
+                x.InvoiceDate,
+                x.CustomerSnapshotName,
+                l.ItemId,
+                l.Description,
+                l.FreeQty,
+                l.FreeQty * l.UnitPrice,
+                l.WarehouseId,
+                x.Warehouse!.Name)))
+            .ToListAsync(ct);
+
+        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.Where(l => l.FreeQty > 0m).Select(l => new SalesFreeIssueSummaryRowDto(
+                "Slip",
+                x.SlipNo,
+                x.SlipDate,
+                x.CustomerSnapshotName,
+                l.ItemId,
+                l.Description,
+                l.FreeQty,
+                l.FreeQty * l.UnitPrice,
+                l.WarehouseId,
+                x.Warehouse!.Name)))
+            .ToListAsync(ct);
+
+        return invoiceRows.Concat(slipRows).OrderByDescending(x => x.FreeQty).ToList();
+    }
+}

Backend/ERPCore/Services/SalesSlipService.cs

@@ -0,0 +1,279 @@
+using ERPCore.Common.Http;
+using ERPCore.Domain;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Sales;
+using ERPCore.Infra.Auth;
+using ERPCore.Infra.UoW;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using ERPCore.System.Errors;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesSlipService : ISalesSlipService
+{
+    private readonly IRepository<SalesSlip> _slips;
+    private readonly IRepository<Customer> _customers;
+    private readonly IRepository<Item> _items;
+    private readonly IRepository<Uom> _uoms;
+    private readonly IRepository<Warehouse> _warehouses;
+    private readonly IRepository<User> _users;
+    private readonly ISalesDomainService _sales;
+    private readonly ISalesPostingService _posting;
+    private readonly ISalesMappingService _mapping;
+    private readonly ISalesDocumentWorkflowService _workflow;
+    private readonly IUomConverter _uomConverter;
+    private readonly ICurrentUser _currentUser;
+    private readonly INumberSequenceService _numbers;
+    private readonly IUnitOfWork _uow;
+
+    public SalesSlipService(
+        IRepository<SalesSlip> slips, IRepository<Customer> customers, IRepository<Item> items,
+        IRepository<Uom> uoms, IRepository<Warehouse> warehouses, IRepository<User> users, ISalesDomainService sales, ISalesPostingService posting, ISalesMappingService mapping,
+        ISalesDocumentWorkflowService workflow, IUomConverter uomConverter,
+        ICurrentUser currentUser, INumberSequenceService numbers, IUnitOfWork uow)
+    {
+        _uomConverter = uomConverter;
+        _slips = slips;
+        _customers = customers;
+        _items = items;
+        _uoms = uoms;
+        _warehouses = warehouses;
+        _users = users;
+        _sales = sales;
+        _posting = posting;
+        _mapping = mapping;
+        _workflow = workflow;
+        _currentUser = currentUser;
+        _numbers = numbers;
+        _uow = uow;
+    }
+
+    public async Task<PagedResponse<SalesSlipSummaryDto>> ListAsync(PageQuery query, SalesSlipStatus? status, int? customerId, int? warehouseId, CancellationToken ct = default)
+    {
+        IQueryable<SalesSlip> q = _slips.Query().AsNoTracking().Include(x => x.Lines);
+        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<SalesSlipSummaryDto>.Create(rows.Select(MapSummary).ToList(), query.Page, query.PageSize, total);
+    }
+
+    public async Task<ETagged<SalesSlipDto>?> GetAsync(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<SalesSlipDto>(_mapping.MapSlip(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 Task<SalesSlipPostingCheckDto> CheckPostingAsync(int salesSlipId, CancellationToken ct = default)
+        => _posting.CheckSlipAsync(salesSlipId, ct);
+
+    public async Task<ETagged<SalesSlipDto>> CreateAsync(CreateSalesSlipRequest request, CancellationToken ct = default)
+    {
+        await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, request.CashierUserId, true, ct);
+
+        var slip = new SalesSlip
+        {
+            SlipNo = await _numbers.NextAsync(DocumentTypes.SalesSlip, ct),
+            SlipDate = DateTime.UtcNow,
+            CustomerId = request.CustomerId,
+            WarehouseId = request.WarehouseId,
+            CashierUserId = request.CashierUserId,
+            Status = SalesSlipStatus.Draft,
+            CreatedAt = DateTime.UtcNow
+        };
+        slip.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
+        slip.Lines = await BuildLinesAsync(request.WarehouseId, request.Lines, ct);
+        Recalculate(slip);
+
+        await _slips.AddAsync(slip, ct);
+        await _uow.SaveChangesAsync(ct);
+        return new ETagged<SalesSlipDto>(_mapping.MapSlip(slip), slip.RowVersion);
+    }
+
+    public async Task<ETagged<SalesSlipDto>> UpdateAsync(int salesSlipId, UpdateSalesSlipRequest request, uint expectedRowVersion, CancellationToken ct = default)
+    {
+        var slip = await _workflow.LoadEditableSlipAsync(salesSlipId, expectedRowVersion, ct);
+
+        await _sales.ValidateSalesHeaderAsync(request.CustomerId, request.WarehouseId, request.CashierUserId, true, ct);
+        slip.CustomerId = request.CustomerId;
+        slip.WarehouseId = request.WarehouseId;
+        slip.CashierUserId = request.CashierUserId;
+        slip.CustomerSnapshotName = await _customers.Query().Where(x => x.CustomerId == request.CustomerId).Select(x => x.DisplayName ?? x.Name).FirstAsync(ct);
+        slip.Lines.Clear();
+        foreach (var line in await BuildLinesAsync(request.WarehouseId, request.Lines, ct)) slip.Lines.Add(line);
+        Recalculate(slip);
+        slip.UpdatedAt = DateTime.UtcNow;
+        await _uow.SaveChangesAsync(ct);
+        return new ETagged<SalesSlipDto>(_mapping.MapSlip(slip), slip.RowVersion);
+    }
+
+    public async Task<SalesSlipDto> PostAsync(int salesSlipId, CancellationToken ct = default)
+        {
+            await _posting.PostSlipAsync(salesSlipId, ct);
+            var slip = await _slips.Query().AsNoTracking().Include(x => x.Lines)
+                .FirstAsync(x => x.SalesSlipId == salesSlipId, ct);
+            return _mapping.MapSlip(slip);
+        }
+
+    public async Task<SalesSlipDto> CancelAsync(int salesSlipId, CancellationToken ct = default)
+    {
+        var slip = await _slips.Query().Include(x => x.Lines).FirstOrDefaultAsync(x => x.SalesSlipId == salesSlipId, ct)
+            ?? throw new NotFoundException($"Sales slip {salesSlipId} was not found.");
+        if (slip.Status != SalesSlipStatus.Draft)
+            throw new ConflictException($"Sales slip {salesSlipId} is {slip.Status} and cannot be cancelled.");
+        slip.Status = SalesSlipStatus.Cancelled;
+        slip.UpdatedAt = DateTime.UtcNow;
+        await _uow.SaveChangesAsync(ct);
+        return _mapping.MapSlip(slip);
+    }
+
+    private async Task<List<SalesSlipLine>> BuildLinesAsync(int headerWarehouseId, List<CreateSalesSlipLineRequest> requests, CancellationToken ct)
+    {
+        var lines = new List<SalesSlipLine>();
+        foreach (var r in requests)
+        {
+            var item = await _items.Query().AsNoTracking().FirstAsync(x => x.ItemId == r.ItemId, ct);
+            await _sales.ValidateSalesLineAsync(headerWarehouseId, r.ItemId, r.UomId, r.WarehouseId, r.Qty, r.FreeQty, r.ParentLineId, ct);
+            var resolved = await _sales.ResolveLinePriceAsync(r.ItemId, r.WarehouseId, r.UnitPrice, r.AllowManualPriceOverride, ct);
+            var unitPrice = resolved.UnitPrice;
+            var priceSource = resolved.PriceSource;
+
+            var calc = _sales.ComputeLine(r.Qty, r.FreeQty, unitPrice, r.DiscountMode, r.DiscountPct, r.DiscountValue, r.DiscountAmount, r.TaxPct, r.IsFreeIssue);
+
+            // Resolve the base quantity now and store it on the line — see the matching
+            // comment in SalesInvoiceService.BuildLinesAsync.
+            var factor = await _uomConverter.ResolveFactorAsync(item, r.UomId, ct);
+
+            lines.Add(new SalesSlipLine
+            {
+                ItemId = r.ItemId,
+                Description = item.Name,
+                Qty = r.Qty,
+                FreeQty = r.FreeQty,
+                UomId = r.UomId,
+                QtyBase = UomConverter.ApplyFactor(r.Qty, factor),
+                FreeQtyBase = UomConverter.ApplyFactor(r.FreeQty, factor),
+                ConversionFactor = factor,
+                WarehouseId = r.WarehouseId,
+                UnitPrice = unitPrice,
+                BaseCost = unitPrice,
+                PriceSource = priceSource,
+                DiscountMode = r.DiscountMode,
+                DiscountPct = r.DiscountPct,
+                DiscountAmount = calc.DiscountTotal,
+                NetUnitPrice = calc.NetUnitPrice,
+                LineTotal = calc.LineTotal,
+                TaxPct = r.TaxPct,
+                TaxAmount = calc.TaxAmount,
+                IsFreeIssue = r.IsFreeIssue,
+                ParentLineId = r.ParentLineId
+            });
+        }
+        return lines;
+    }
+
+    private static void Recalculate(SalesSlip slip)
+    {
+        slip.Subtotal = slip.Lines.Sum(x => x.Qty * x.UnitPrice);
+        slip.DiscountTotal = slip.Lines.Sum(x => x.DiscountAmount);
+        slip.TaxTotal = slip.Lines.Sum(x => x.TaxAmount);
+        slip.GrandTotal = slip.Lines.Sum(x => x.LineTotal) + slip.TaxTotal;
+        slip.PaidAmount = 0m;
+        slip.BalanceAmount = slip.GrandTotal - slip.PaidAmount;
+    }
+
+    private SalesSlipSummaryDto MapSummary(SalesSlip x) => new(
+        x.SalesSlipId, x.SlipNo, x.SlipDate, x.CustomerId, x.CustomerSnapshotName, x.WarehouseId, x.Status,
+        _mapping.MapSlipTotals(x), 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 SalesSlipDto Map(SalesSlip x) => _mapping.MapSlip(x);
+}