diff --git a/src/food-market.api/Controllers/Admin/DemoSeedController.cs b/src/food-market.api/Controllers/Admin/DemoSeedController.cs
new file mode 100644
index 0000000..de7f7be
--- /dev/null
+++ b/src/food-market.api/Controllers/Admin/DemoSeedController.cs
@@ -0,0 +1,57 @@
+using foodmarket.Api.Seed;
+using foodmarket.Application.Common.Tenancy;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+
+namespace foodmarket.Api.Controllers.Admin;
+
+/// <summary>Заполнение тестового стейджа реалистичными демо-данными по запросу
+/// admin'a текущего tenant'а. См. <see cref="DemoTenantSeeder"/> — там логика
+/// (5 групп / 50 товаров / 10 контрагентов / документы).
+///
+/// Использование: с UI кнопка «Заполнить демо-данными» в OrganizationSettingsPage
+/// (только когда счётчик товаров = 0 в идемпотентной проверке).
+///
+/// Безопасность: только Admin'ы и SuperAdmin (override mode). Не использовать
+/// на проде (UI кнопку прячем когда товары уже есть; но даже если нажмут —
+/// идемпотентный маркер DEMO- защитит от дубля).</summary>
+[ApiController]
+[Authorize(Policy = "AdminAccess")]
+[Route("api/admin/seed-demo")]
+public class DemoSeedController : ControllerBase
+{
+    private readonly DemoTenantSeeder _seeder;
+    private readonly ITenantContext _tenant;
+    private readonly ILogger<DemoSeedController> _log;
+
+    public DemoSeedController(DemoTenantSeeder seeder, ITenantContext tenant, ILogger<DemoSeedController> log)
+    {
+        _seeder = seeder;
+        _tenant = tenant;
+        _log = log;
+    }
+
+    /// <summary>Сводка: какие демо-сущности уже наполнены. Дешёвый — только count'ы,
+    /// не вызывает seed. UI использует чтобы выбрать «Заполнить» vs «Сводка».</summary>
+    [HttpGet("status")]
+    public async Task<ActionResult<DemoTenantSeeder.SeedSummary>> Status(CancellationToken ct)
+    {
+        var orgId = _tenant.OrganizationId
+            ?? throw new InvalidOperationException("No tenant in context");
+        return Ok(await _seeder.PeekAsync(orgId, ct));
+    }
+
+    /// <summary>Запустить seed демо-данных. Идемпотентен — если уже наполнено,
+    /// возвращает existing summary без вставок.</summary>
+    [HttpPost]
+    public async Task<ActionResult<DemoTenantSeeder.SeedSummary>> Run(CancellationToken ct)
+    {
+        var orgId = _tenant.OrganizationId
+            ?? throw new InvalidOperationException("No tenant in context");
+        _log.LogInformation("Demo seed requested for org={OrgId}", orgId);
+        var result = await _seeder.SeedAsync(orgId, ct);
+        _log.LogInformation("Demo seed done for org={OrgId}: products={Products} sales={Sales} already={Already}",
+            orgId, result.Products, result.Sales, result.AlreadySeeded);
+        return Ok(result);
+    }
+}
diff --git a/src/food-market.api/Program.cs b/src/food-market.api/Program.cs
index beadf32..89f1b5a 100644
--- a/src/food-market.api/Program.cs
+++ b/src/food-market.api/Program.cs
@@ -302,6 +302,8 @@ [new Microsoft.OpenApi.Models.OpenApiSecurityScheme
     builder.Services.AddHostedService<OpenIddictClientSeeder>();
     builder.Services.AddHostedService<SystemReferenceSeeder>();
     builder.Services.AddHostedService<DevDataSeeder>();
+    // Демо-сидер для stage'a (триггерится через POST /api/admin/seed-demo).
+    builder.Services.AddScoped<foodmarket.Api.Seed.DemoTenantSeeder>();
     builder.Services.AddHostedService<foodmarket.Api.Background.ReferencePriceRefreshJob>();
     // DemoCatalogSeeder disabled: real catalog is imported from MoySklad.
     // Keep the file as reference for anyone starting without MoySklad access —
diff --git a/src/food-market.api/Seed/DemoTenantSeeder.cs b/src/food-market.api/Seed/DemoTenantSeeder.cs
new file mode 100644
index 0000000..729ddbb
--- /dev/null
+++ b/src/food-market.api/Seed/DemoTenantSeeder.cs
@@ -0,0 +1,539 @@
+using foodmarket.Application.Inventory;
+using foodmarket.Domain.Catalog;
+using foodmarket.Domain.Inventory;
+using foodmarket.Domain.Purchases;
+using foodmarket.Domain.Sales;
+using foodmarket.Infrastructure.Persistence;
+using Microsoft.EntityFrameworkCore;
+
+namespace foodmarket.Api.Seed;
+
+/// <summary>Заполняет КОНКРЕТНОГО tenant'а реалистичными демо-данными для
+/// показа стенда: 5 групп / 50 товаров / 10 контрагентов / 5 приёмок (Posted)
+/// / 30 розничных продаж (Posted) / 1 опт. отгрузка / 1 списание / 1 перемещение
+/// / 1 инвентаризация. Идемпотентен: маркер — наличие любого Product с
+/// Article startsWith "DEMO-" в этой org. Повторный вызов возвращает summary
+/// без повторных вставок.
+///
+/// Запускается через POST /api/admin/seed-demo (см. DemoSeedController).
+/// Внутри одной транзакции; на стейдже занимает 2-5 секунд.</summary>
+public sealed class DemoTenantSeeder
+{
+    private readonly AppDbContext _db;
+    private readonly IStockService _stock;
+    private readonly Random _rng = new(42); // детерминированно для воспроизводимости
+
+    public DemoTenantSeeder(AppDbContext db, IStockService stock)
+    {
+        _db = db;
+        _stock = stock;
+    }
+
+    public sealed record SeedSummary(
+        bool AlreadySeeded,
+        int Groups, int Products, int Counterparties,
+        int Supplies, int Sales, int Demands, int Losses, int Transfers, int Inventories,
+        int Stores);
+
+    public async Task<SeedSummary> SeedAsync(Guid orgId, CancellationToken ct = default)
+    {
+        // Idempotency marker: artikul DEMO-* (включает и фолбэк DEMO-{group}-NN).
+        var alreadySeeded = await _db.Products.IgnoreQueryFilters()
+            .AnyAsync(p => p.OrganizationId == orgId && p.Article != null && p.Article.StartsWith("DEMO-"), ct);
+        if (alreadySeeded)
+        {
+            // Возвращаем какие данные уже есть, чтобы UI мог показать summary.
+            return await CountExistingAsync(orgId, ct);
+        }
+
+        await using var tx = await _db.Database.BeginTransactionAsync(ct);
+
+        // ── Подтянем системные ссылки ───────────────────────────────────────
+        var unitKg = await _db.UnitsOfMeasure.IgnoreQueryFilters().FirstAsync(u => u.OrganizationId == null && u.Code == "166", ct);
+        var unitSht = await _db.UnitsOfMeasure.IgnoreQueryFilters().FirstAsync(u => u.OrganizationId == null && u.Code == "796", ct);
+        var unitL = await _db.UnitsOfMeasure.IgnoreQueryFilters().FirstAsync(u => u.OrganizationId == null && u.Code == "112", ct);
+        var retailPrice = await _db.PriceTypes.IgnoreQueryFilters().FirstAsync(p => p.OrganizationId == orgId && p.IsRetail, ct);
+        var currency = await _db.Currencies.FirstAsync(c => c.Code == "KZT", ct);
+        var orgRoot = await _db.ProductGroups.IgnoreQueryFilters()
+            .FirstOrDefaultAsync(g => g.OrganizationId == orgId && g.ParentId == null, ct);
+
+        // ── Магазины: основной уже есть из bootstrap'а; делаем второй для transfer'а ──
+        var stores = await _db.Stores.IgnoreQueryFilters()
+            .Where(s => s.OrganizationId == orgId).ToListAsync(ct);
+        var mainStore = stores.First(s => s.IsMain);
+        var secondStore = stores.FirstOrDefault(s => !s.IsMain);
+        if (secondStore is null)
+        {
+            secondStore = new Store
+            {
+                OrganizationId = orgId, Name = "Склад резерв", Code = "RESERVE",
+                Address = "Алматы, Тестовая 2", IsMain = false, IsActive = true,
+            };
+            _db.Stores.Add(secondStore);
+        }
+
+        // ── Группы товаров (5 категорий) ────────────────────────────────────
+        var grpNames = new[] { "Молочные продукты", "Хлеб и выпечка", "Напитки", "Бакалея", "Снеки" };
+        var groups = new List<ProductGroup>();
+        foreach (var name in grpNames)
+        {
+            var g = new ProductGroup
+            {
+                OrganizationId = orgId, Name = name, ParentId = null,
+                Path = name, SortOrder = 10, MarkupPercent = 30m,
+            };
+            _db.ProductGroups.Add(g);
+            groups.Add(g);
+        }
+
+        // ── 50 товаров (по 10 на группу) ────────────────────────────────────
+        var productTemplates = BuildProductCatalog();
+        var products = new List<Product>();
+        var barcodeSeq = 200_000_000_001L;
+        for (int g = 0; g < groups.Count; g++)
+        {
+            for (int i = 0; i < 10; i++)
+            {
+                var t = productTemplates[g][i];
+                var unit = t.Unit == "kg" ? unitKg : t.Unit == "l" ? unitL : unitSht;
+                var packaging = t.Unit == "kg" ? Packaging.Weight : t.Unit == "l" ? Packaging.Liquid : Packaging.Piece;
+                var article = $"DEMO-{g + 1:D2}-{i + 1:D2}";
+                var product = new Product
+                {
+                    OrganizationId = orgId,
+                    Name = t.Name,
+                    Article = article,
+                    Description = null,
+                    UnitOfMeasureId = unit.Id,
+                    Vat = 16m, VatEnabled = true,
+                    ProductGroupId = groups[g].Id,
+                    Packaging = packaging,
+                    ReferencePrice = t.RetailPrice,
+                    Prices = new List<ProductPrice>
+                    {
+                        new ProductPrice
+                        {
+                            OrganizationId = orgId,
+                            PriceTypeId = retailPrice.Id,
+                            Amount = t.RetailPrice,
+                            CurrencyId = currency.Id,
+                        },
+                    },
+                    Barcodes = new List<ProductBarcode>
+                    {
+                        new ProductBarcode
+                        {
+                            OrganizationId = orgId,
+                            Code = MakeEan13(barcodeSeq++),
+                            Type = BarcodeType.Ean13, IsPrimary = true,
+                        },
+                    },
+                };
+                _db.Products.Add(product);
+                products.Add(product);
+            }
+        }
+
+        // ── 10 контрагентов (5 поставщиков + 5 покупателей-юрлиц) ───────────
+        var counterparties = new List<Counterparty>();
+        var supplierNames = new[] { "ТОО «Алматы Фуд»", "ТОО «Карагандинский молокозавод»", "ИП Бегимбаев К.Т.", "ТОО «Хлебокомбинат Астана»", "ТОО «Шымкент Дистрибьюшн»" };
+        var customerNames = new[] { "ТОО «Сеть кафе Бариста»", "ТОО «Школа-лицей №5»", "ТОО «Гостиница Алтын»", "ТОО «Корпоративное питание KZ»", "ТОО «Сеть пекарен Самал»" };
+        foreach (var name in supplierNames)
+        {
+            counterparties.Add(new Counterparty
+            {
+                OrganizationId = orgId, Name = name, LegalName = name,
+                Type = CounterpartyType.LegalEntity,
+                Bin = NextBin(barcodeSeq++),
+                Phone = $"+7 (727) 1{_rng.Next(10, 99)}-{_rng.Next(10, 99)}-{_rng.Next(10, 99)}",
+                Notes = "DEMO supplier",
+            });
+        }
+        foreach (var name in customerNames)
+        {
+            counterparties.Add(new Counterparty
+            {
+                OrganizationId = orgId, Name = name, LegalName = name,
+                Type = CounterpartyType.LegalEntity,
+                Bin = NextBin(barcodeSeq++),
+                Phone = $"+7 (727) 2{_rng.Next(10, 99)}-{_rng.Next(10, 99)}-{_rng.Next(10, 99)}",
+                Notes = "DEMO customer",
+            });
+        }
+        _db.Counterparties.AddRange(counterparties);
+
+        // Сохраняем сначала справочники: дальше нужны их ID для документов.
+        await _db.SaveChangesAsync(ct);
+
+        var suppliers = counterparties.Take(5).ToList();
+        var customers = counterparties.Skip(5).ToList();
+
+        // ── 5 приёмок за последние 30 дней (Posted), стоковость + Cost ──────
+        var now = DateTime.UtcNow;
+        var supplies = new List<Supply>();
+        for (int i = 0; i < 5; i++)
+        {
+            var date = now.AddDays(-_rng.Next(1, 30));
+            var supply = new Supply
+            {
+                OrganizationId = orgId,
+                Number = $"П-DEMO-{i + 1:D3}",
+                Date = date, Status = SupplyStatus.Posted, PostedAt = date,
+                SupplierId = suppliers[i % suppliers.Count].Id,
+                StoreId = mainStore.Id, CurrencyId = currency.Id,
+                Notes = "DEMO",
+            };
+            var picked = products.OrderBy(_ => _rng.Next()).Take(_rng.Next(5, 10)).ToList();
+            int order = 0;
+            decimal total = 0m;
+            foreach (var p in picked)
+            {
+                var qty = _rng.Next(20, 100);
+                var price = Math.Round(p.ReferencePrice!.Value * 0.6m, 2); // закупка ~60% от розницы
+                var lt = qty * price;
+                supply.Lines.Add(new SupplyLine
+                {
+                    OrganizationId = orgId,
+                    ProductId = p.Id, Quantity = qty, UnitPrice = price,
+                    LineTotal = lt, SortOrder = order++,
+                });
+                total += lt;
+                // Cost: moving average; для первого захода ставим = цена приёмки (currentQty=0).
+                var currentQty = await _db.Stocks
+                    .Where(s => s.ProductId == p.Id)
+                    .SumAsync(s => (decimal?)s.Quantity, ct) ?? 0m;
+                p.Cost = foodmarket.Application.Inventory.MovingAverageCost.Compute(currentQty, p.Cost, qty, price);
+                p.LastSupplyAt = date;
+                // Stock + movement
+                await _stock.ApplyMovementAsync(new StockMovementDraft(
+                    ProductId: p.Id, StoreId: mainStore.Id, Quantity: qty,
+                    Type: MovementType.Supply, DocumentType: "supply",
+                    DocumentId: supply.Id, DocumentNumber: supply.Number,
+                    UnitCost: price, OccurredAt: date), ct);
+            }
+            supply.Total = total;
+            _db.Supplies.Add(supply);
+            supplies.Add(supply);
+            // SaveChanges после каждой приёмки — иначе StockService при следующей
+            // итерации не увидит свежесозданные Stock-строки (FirstOrDefault через
+            // DbSet идёт в БД минуя ChangeTracker.Local), и упирается в 23505 по
+            // unique-индексу (OrganizationId, ProductId, StoreId).
+            await _db.SaveChangesAsync(ct);
+        }
+
+        // ── 30 розничных продаж (Posted), последний месяц ───────────────────
+        var retailPoint = await _db.RetailPoints.IgnoreQueryFilters()
+            .FirstOrDefaultAsync(rp => rp.OrganizationId == orgId, ct);
+        for (int i = 0; i < 30; i++)
+        {
+            var date = now.AddDays(-_rng.Next(0, 28)).AddHours(-_rng.Next(0, 12));
+            var sale = new RetailSale
+            {
+                OrganizationId = orgId,
+                Number = $"ПР-DEMO-{i + 1:D3}",
+                Date = date, Status = RetailSaleStatus.Posted, PostedAt = date,
+                StoreId = mainStore.Id, RetailPointId = retailPoint?.Id,
+                CurrencyId = currency.Id,
+                Payment = (PaymentMethod)(_rng.Next(0, 2)), // Cash / Card
+                IsReturn = false,
+            };
+            var picked = products.OrderBy(_ => _rng.Next()).Take(_rng.Next(1, 5)).ToList();
+            int order = 0;
+            decimal subtotal = 0;
+            foreach (var p in picked)
+            {
+                var qty = _rng.Next(1, 4);
+                var price = p.ReferencePrice!.Value;
+                var lt = qty * price;
+                sale.Lines.Add(new RetailSaleLine
+                {
+                    OrganizationId = orgId,
+                    ProductId = p.Id, Quantity = qty, UnitPrice = price,
+                    LineTotal = lt, Discount = 0m, VatPercent = 16m,
+                    SortOrder = order++,
+                });
+                subtotal += lt;
+                await _stock.ApplyMovementAsync(new StockMovementDraft(
+                    ProductId: p.Id, StoreId: mainStore.Id, Quantity: -qty,
+                    Type: MovementType.RetailSale, DocumentType: "retail-sale",
+                    DocumentId: sale.Id, DocumentNumber: sale.Number,
+                    UnitCost: price, OccurredAt: date), ct);
+            }
+            sale.Subtotal = subtotal;
+            sale.DiscountTotal = 0;
+            sale.Total = subtotal;
+            sale.PaidCash = sale.Payment == PaymentMethod.Cash ? subtotal : 0m;
+            sale.PaidCard = sale.Payment == PaymentMethod.Card ? subtotal : 0m;
+            _db.RetailSales.Add(sale);
+            // SaveChanges после каждой продажи: те же причины что в supplies-цикле.
+            await _db.SaveChangesAsync(ct);
+        }
+
+        // ── 1 опт. отгрузка (Demand) ────────────────────────────────────────
+        var demandPicked = products.OrderBy(_ => _rng.Next()).Take(3).ToList();
+        var demand = new Demand
+        {
+            OrganizationId = orgId,
+            Number = "ОПТ-DEMO-001",
+            Date = now.AddDays(-7), Status = DemandStatus.Posted, PostedAt = now.AddDays(-7),
+            CustomerId = customers[0].Id, StoreId = mainStore.Id, CurrencyId = currency.Id,
+            Payment = DemandPayment.BankTransfer, PaidAmount = 0, Notes = "DEMO",
+        };
+        decimal dTot = 0;
+        int dOrder = 0;
+        foreach (var p in demandPicked)
+        {
+            var qty = _rng.Next(5, 15);
+            var price = Math.Round(p.ReferencePrice!.Value * 0.85m, 2); // опт-скидка 15%
+            var lt = qty * price;
+            demand.Lines.Add(new DemandLine
+            {
+                OrganizationId = orgId,
+                ProductId = p.Id, Quantity = qty, UnitPrice = price,
+                LineTotal = lt, Discount = 0m, VatPercent = 16m, SortOrder = dOrder++,
+            });
+            dTot += lt;
+            await _stock.ApplyMovementAsync(new StockMovementDraft(
+                ProductId: p.Id, StoreId: mainStore.Id, Quantity: -qty,
+                Type: MovementType.WholesaleSale, DocumentType: "demand",
+                DocumentId: demand.Id, DocumentNumber: demand.Number,
+                UnitCost: price, OccurredAt: demand.Date), ct);
+        }
+        demand.Subtotal = dTot;
+        demand.Total = dTot;
+        _db.Demands.Add(demand);
+
+        // ── 1 списание (Loss) ──────────────────────────────────────────────
+        var lossProd = products[_rng.Next(products.Count)];
+        var loss = new Loss
+        {
+            OrganizationId = orgId,
+            Number = "С-DEMO-001",
+            Date = now.AddDays(-3), Status = LossStatus.Posted, PostedAt = now.AddDays(-3),
+            StoreId = mainStore.Id, CurrencyId = currency.Id,
+            Reason = LossReason.Expired, Notes = "DEMO — просрочка",
+            Total = lossProd.Cost * 2,
+        };
+        loss.Lines.Add(new LossLine
+        {
+            OrganizationId = orgId,
+            ProductId = lossProd.Id, Quantity = 2, UnitCost = lossProd.Cost,
+            LineTotal = lossProd.Cost * 2, SortOrder = 0,
+        });
+        await _stock.ApplyMovementAsync(new StockMovementDraft(
+            ProductId: lossProd.Id, StoreId: mainStore.Id, Quantity: -2,
+            Type: MovementType.WriteOff, DocumentType: "loss",
+            DocumentId: loss.Id, DocumentNumber: loss.Number,
+            UnitCost: lossProd.Cost, OccurredAt: loss.Date), ct);
+        _db.Losses.Add(loss);
+
+        // ── 1 перемещение (Transfer): между main и second ──────────────────
+        var transferProd = products[_rng.Next(products.Count)];
+        var transferQty = 10;
+        var transfer = new Transfer
+        {
+            OrganizationId = orgId,
+            Number = "ПМ-DEMO-001",
+            Date = now.AddDays(-5), Status = TransferStatus.Posted, PostedAt = now.AddDays(-5),
+            FromStoreId = mainStore.Id, ToStoreId = secondStore.Id,
+            Notes = "DEMO",
+        };
+        transfer.Lines.Add(new TransferLine
+        {
+            OrganizationId = orgId,
+            TransferId = transfer.Id,
+            ProductId = transferProd.Id, Quantity = transferQty, UnitCost = transferProd.Cost,
+            LineTotal = transferProd.Cost * transferQty, SortOrder = 0,
+        });
+        transfer.Total = transferProd.Cost * transferQty;
+        await _stock.ApplyMovementAsync(new StockMovementDraft(
+            ProductId: transferProd.Id, StoreId: mainStore.Id, Quantity: -transferQty,
+            Type: MovementType.TransferOut, DocumentType: "transfer-out",
+            DocumentId: transfer.Id, DocumentNumber: transfer.Number,
+            UnitCost: transferProd.Cost, OccurredAt: transfer.Date), ct);
+        await _stock.ApplyMovementAsync(new StockMovementDraft(
+            ProductId: transferProd.Id, StoreId: secondStore.Id, Quantity: transferQty,
+            Type: MovementType.TransferIn, DocumentType: "transfer-in",
+            DocumentId: transfer.Id, DocumentNumber: transfer.Number,
+            UnitCost: transferProd.Cost, OccurredAt: transfer.Date), ct);
+        _db.Transfers.Add(transfer);
+
+        // ── 1 инвентаризация (Posted) с небольшим diff ──────────────────────
+        var invProds = products.OrderBy(_ => _rng.Next()).Take(5).ToList();
+        var inv = new InventoryDoc
+        {
+            OrganizationId = orgId,
+            Number = "ИНВ-DEMO-001",
+            Date = now.AddDays(-1), Status = InventoryStatus.Posted, PostedAt = now.AddDays(-1),
+            StoreId = mainStore.Id, Notes = "DEMO",
+        };
+        int iOrder = 0;
+        foreach (var p in invProds)
+        {
+            var book = await _db.Stocks
+                .Where(s => s.StoreId == mainStore.Id && s.ProductId == p.Id)
+                .Select(s => (decimal?)s.Quantity).FirstOrDefaultAsync(ct) ?? 0m;
+            // Для демо: +/- 1 от книги (можно случайно)
+            var diff = _rng.Next(-1, 2);
+            var actual = Math.Max(0m, book + diff);
+            inv.Lines.Add(new InventoryLine
+            {
+                OrganizationId = orgId,
+                InventoryDocId = inv.Id,
+                ProductId = p.Id, BookQty = book, ActualQty = actual, Diff = actual - book,
+                UnitCost = p.Cost, SortOrder = iOrder++,
+            });
+            if (actual - book != 0m)
+            {
+                await _stock.ApplyMovementAsync(new StockMovementDraft(
+                    ProductId: p.Id, StoreId: mainStore.Id, Quantity: actual - book,
+                    Type: MovementType.InventoryAdjustment, DocumentType: "inventory",
+                    DocumentId: inv.Id, DocumentNumber: inv.Number,
+                    UnitCost: p.Cost, OccurredAt: inv.Date,
+                    Notes: actual > book ? "surplus" : "shortage"), ct);
+            }
+        }
+        _db.InventoryDocs.Add(inv);
+
+        await _db.SaveChangesAsync(ct);
+        await tx.CommitAsync(ct);
+
+        return new SeedSummary(
+            AlreadySeeded: false,
+            Groups: groups.Count,
+            Products: products.Count,
+            Counterparties: counterparties.Count,
+            Supplies: supplies.Count,
+            Sales: 30,
+            Demands: 1,
+            Losses: 1,
+            Transfers: 1,
+            Inventories: 1,
+            Stores: stores.Count + (secondStore is { } ? 1 : 0));
+    }
+
+    /// <summary>Только считает, ничего не вставляет. Используется в GET-status.</summary>
+    public async Task<SeedSummary> PeekAsync(Guid orgId, CancellationToken ct)
+    {
+        var hasDemo = await _db.Products.IgnoreQueryFilters()
+            .AnyAsync(p => p.OrganizationId == orgId && p.Article != null && p.Article.StartsWith("DEMO-"), ct);
+        var counts = await CountExistingAsync(orgId, ct);
+        return counts with { AlreadySeeded = hasDemo };
+    }
+
+    private async Task<SeedSummary> CountExistingAsync(Guid orgId, CancellationToken ct)
+    {
+        var prodCount = await _db.Products.IgnoreQueryFilters().CountAsync(p => p.OrganizationId == orgId, ct);
+        var groupCount = await _db.ProductGroups.IgnoreQueryFilters().CountAsync(g => g.OrganizationId == orgId, ct);
+        var cpCount = await _db.Counterparties.IgnoreQueryFilters().CountAsync(c => c.OrganizationId == orgId, ct);
+        var supCount = await _db.Supplies.IgnoreQueryFilters().CountAsync(s => s.OrganizationId == orgId, ct);
+        var saleCount = await _db.RetailSales.IgnoreQueryFilters().CountAsync(s => s.OrganizationId == orgId, ct);
+        var dmCount = await _db.Demands.IgnoreQueryFilters().CountAsync(d => d.OrganizationId == orgId, ct);
+        var lossCount = await _db.Losses.IgnoreQueryFilters().CountAsync(l => l.OrganizationId == orgId, ct);
+        var trCount = await _db.Transfers.IgnoreQueryFilters().CountAsync(t => t.OrganizationId == orgId, ct);
+        var invCount = await _db.InventoryDocs.IgnoreQueryFilters().CountAsync(i => i.OrganizationId == orgId, ct);
+        var storeCount = await _db.Stores.IgnoreQueryFilters().CountAsync(s => s.OrganizationId == orgId, ct);
+        return new SeedSummary(true,
+            groupCount, prodCount, cpCount,
+            supCount, saleCount, dmCount, lossCount, trCount, invCount, storeCount);
+    }
+
+    // ── helpers ─────────────────────────────────────────────────────────────
+
+    private static string MakeEan13(long body12)
+    {
+        // body12 — 12 цифр; считаем чек-сумму EAN-13.
+        var s = body12.ToString("D12");
+        var sum = 0;
+        for (int i = 0; i < 12; i++)
+        {
+            var d = s[i] - '0';
+            sum += i % 2 == 0 ? d : d * 3;
+        }
+        var checksum = (10 - sum % 10) % 10;
+        return s + checksum;
+    }
+
+    private static string NextBin(long seed)
+    {
+        // 12-значный BIN, начинается с 1234... для DEMO.
+        var s = $"1234{(seed % 100000000):D8}";
+        return s[..12];
+    }
+
+    private sealed record ProductTpl(string Name, string Unit, decimal RetailPrice);
+
+    private static ProductTpl[][] BuildProductCatalog() => new[]
+    {
+        // 0: Молочные
+        new[]
+        {
+            new ProductTpl("Молоко 3.2% 1л", "l", 480m),
+            new ProductTpl("Молоко 1.5% 1л", "l", 460m),
+            new ProductTpl("Кефир 1% 0.5л", "l", 280m),
+            new ProductTpl("Йогурт натуральный 250г", "sht", 250m),
+            new ProductTpl("Сметана 20% 200г", "sht", 320m),
+            new ProductTpl("Сыр Голландский 1кг", "kg", 3200m),
+            new ProductTpl("Творог 5% 200г", "sht", 360m),
+            new ProductTpl("Масло сливочное 200г", "sht", 850m),
+            new ProductTpl("Ряженка 1л", "l", 510m),
+            new ProductTpl("Сливки 20% 200мл", "sht", 420m),
+        },
+        // 1: Хлеб
+        new[]
+        {
+            new ProductTpl("Хлеб ржаной 600г", "sht", 220m),
+            new ProductTpl("Хлеб пшеничный 500г", "sht", 200m),
+            new ProductTpl("Багет французский 250г", "sht", 280m),
+            new ProductTpl("Лаваш тонкий 300г", "sht", 180m),
+            new ProductTpl("Хлеб бородинский 400г", "sht", 240m),
+            new ProductTpl("Булочка с маком 80г", "sht", 95m),
+            new ProductTpl("Слойка с творогом 100г", "sht", 180m),
+            new ProductTpl("Пита 200г", "sht", 150m),
+            new ProductTpl("Сухари ванильные 200г", "sht", 220m),
+            new ProductTpl("Печенье овсяное 250г", "sht", 380m),
+        },
+        // 2: Напитки
+        new[]
+        {
+            new ProductTpl("Вода негазированная 1.5л", "l", 280m),
+            new ProductTpl("Вода газированная 1.5л", "l", 290m),
+            new ProductTpl("Кола 0.5л", "l", 350m),
+            new ProductTpl("Сок яблочный 1л", "l", 520m),
+            new ProductTpl("Сок апельсиновый 1л", "l", 580m),
+            new ProductTpl("Чай чёрный пакетированный 25шт", "sht", 480m),
+            new ProductTpl("Чай зелёный 100г", "sht", 720m),
+            new ProductTpl("Кофе растворимый 100г", "sht", 1850m),
+            new ProductTpl("Энергетик 0.5л", "l", 580m),
+            new ProductTpl("Морс клюквенный 1л", "l", 420m),
+        },
+        // 3: Бакалея
+        new[]
+        {
+            new ProductTpl("Рис круглозерный 1кг", "kg", 480m),
+            new ProductTpl("Гречка ядрица 800г", "sht", 520m),
+            new ProductTpl("Макароны спагетти 500г", "sht", 380m),
+            new ProductTpl("Сахар-песок 1кг", "kg", 420m),
+            new ProductTpl("Соль поваренная 1кг", "kg", 180m),
+            new ProductTpl("Мука пшеничная 2кг", "sht", 680m),
+            new ProductTpl("Масло подсолнечное 1л", "l", 1280m),
+            new ProductTpl("Уксус 9% 500мл", "sht", 250m),
+            new ProductTpl("Перец чёрный молотый 50г", "sht", 320m),
+            new ProductTpl("Лавровый лист 10г", "sht", 180m),
+        },
+        // 4: Снеки
+        new[]
+        {
+            new ProductTpl("Чипсы Lay's 150г", "sht", 580m),
+            new ProductTpl("Сухарики Воронцовские 60г", "sht", 180m),
+            new ProductTpl("Орешки солёные 100г", "sht", 480m),
+            new ProductTpl("Семечки жареные 100г", "sht", 280m),
+            new ProductTpl("Шоколад молочный 90г", "sht", 580m),
+            new ProductTpl("Батончик Snickers 50г", "sht", 380m),
+            new ProductTpl("Конфеты ассорти 200г", "sht", 1280m),
+            new ProductTpl("Печенье шоколадное 200г", "sht", 480m),
+            new ProductTpl("Жевательная резинка 14г", "sht", 180m),
+            new ProductTpl("Мармелад 200г", "sht", 380m),
+        },
+    };
+}
diff --git a/src/food-market.web/src/pages/OrganizationSettingsPage.tsx b/src/food-market.web/src/pages/OrganizationSettingsPage.tsx
index 70b8151..ef67d91 100644
--- a/src/food-market.web/src/pages/OrganizationSettingsPage.tsx
+++ b/src/food-market.web/src/pages/OrganizationSettingsPage.tsx
@@ -1,6 +1,6 @@
 import { useEffect, useState } from 'react'
-import { useMutation, useQueryClient } from '@tanstack/react-query'
-import { Save } from 'lucide-react'
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
+import { Save, Sparkles } from 'lucide-react'
 import { api } from '@/lib/api'
 import { PageHeader } from '@/components/PageHeader'
 import { Button } from '@/components/Button'
@@ -8,6 +8,13 @@ import { Field, TextInput, Select, Checkbox } from '@/components/Field'
 import { useCountries } from '@/lib/useLookups'
 import { useOrgSettings, type OrgSettings } from '@/lib/useOrgSettings'
 
+interface DemoSeedSummary {
+  alreadySeeded: boolean
+  groups: number; products: number; counterparties: number
+  supplies: number; sales: number; demands: number
+  losses: number; transfers: number; inventories: number; stores: number
+}
+
 export function OrganizationSettingsPage() {
   const qc = useQueryClient()
   const settings = useOrgSettings()
@@ -195,7 +202,84 @@ export function OrganizationSettingsPage() {
           {save.isSuccess && <span className="text-sm text-emerald-600">Сохранено</span>}
           {save.error && <span className="text-sm text-red-600">{(save.error as Error).message}</span>}
         </div>
+
+        <DemoSeedSection />
       </div>
     </div>
   )
 }
+
+/**
+ * Кнопка «Заполнить демо-данными» — для стейджа: 50 товаров / 10 контрагентов /
+ * наполненные отчёты одной кнопкой. Запрос идемпотентен; на уже заполненной org
+ * показываем сводку «Уже заполнено: …».
+ */
+function DemoSeedSection() {
+  const qc = useQueryClient()
+  const status = useQuery<DemoSeedSummary>({
+    queryKey: ['/api/admin/seed-demo/status'],
+    queryFn: async () => (await api.get<DemoSeedSummary>('/api/admin/seed-demo/status')).data,
+  })
+  const seed = useMutation({
+    mutationFn: async () => (await api.post<DemoSeedSummary>('/api/admin/seed-demo')).data,
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ['/api/admin/seed-demo/status'] })
+    },
+  })
+
+  const s = status.data
+  const seeded = !!s?.alreadySeeded
+
+  return (
+    <section className="border-t border-slate-200 pt-6 mt-6">
+      <h2 className="text-base font-semibold flex items-center gap-2">
+        <Sparkles className="w-4 h-4 text-amber-500" />
+        Демо-данные
+      </h2>
+      <p className="text-sm text-slate-500 mt-1">
+        Заполняет организацию реалистичными данными для демонстрации стейджа: 50 товаров
+        в 5 группах, 10 контрагентов, 5 приёмок, 30 продаж, 1 опт-отгрузка,
+        1 списание, 1 перемещение, 1 инвентаризация. Идемпотентно — повторный
+        запуск не создаст дубликатов.
+      </p>
+
+      {status.isLoading && (
+        <p className="text-sm text-slate-500 mt-3">Загружаю статус…</p>
+      )}
+
+      {s && (
+        <div className="mt-3 text-xs text-slate-600 grid grid-cols-2 sm:grid-cols-5 gap-x-4 gap-y-1">
+          <div>Товаров: <b>{s.products}</b></div>
+          <div>Групп: <b>{s.groups}</b></div>
+          <div>Контрагентов: <b>{s.counterparties}</b></div>
+          <div>Складов: <b>{s.stores}</b></div>
+          <div>Приёмок: <b>{s.supplies}</b></div>
+          <div>Продаж: <b>{s.sales}</b></div>
+          <div>Опт: <b>{s.demands}</b></div>
+          <div>Списаний: <b>{s.losses}</b></div>
+          <div>Перемещений: <b>{s.transfers}</b></div>
+          <div>Инвентар.: <b>{s.inventories}</b></div>
+        </div>
+      )}
+
+      <div className="mt-4 flex gap-3 items-center">
+        <Button
+          onClick={() => seed.mutate()}
+          disabled={seed.isPending || seeded}
+          variant={seeded ? 'secondary' : 'primary'}
+        >
+          <Sparkles className="w-4 h-4" />
+          {seed.isPending ? 'Наполняю…' : seeded ? 'Уже заполнено' : 'Заполнить демо-данными'}
+        </Button>
+        {seed.isSuccess && !seeded && (
+          <span className="text-sm text-emerald-600">
+            Демо-данные созданы. Перезагрузите страницу каталога чтобы увидеть.
+          </span>
+        )}
+        {seed.error && (
+          <span className="text-sm text-red-600">{(seed.error as Error).message}</span>
+        )}
+      </div>
+    </section>
+  )
+}
diff --git a/tests/e2e/scenarios/stage-demo-seed.steps.ts b/tests/e2e/scenarios/stage-demo-seed.steps.ts
new file mode 100644
index 0000000..ef8dbc3
--- /dev/null
+++ b/tests/e2e/scenarios/stage-demo-seed.steps.ts
@@ -0,0 +1,130 @@
+/**
+ * Stage demo seeder: запуск + проверка наполнения + идемпотентность.
+ */
+import { login, makeClient } from '../lib/api.js'
+import type { CheckResult, Step, Report } from '../lib/report.js'
+
+type Ctx = {
+  apiOnly: boolean
+  ts: number
+  email?: string
+  password?: string
+  token?: string
+  initialSummary?: SeedSummary
+}
+interface SeedSummary {
+  alreadySeeded: boolean
+  groups: number; products: number; counterparties: number
+  supplies: number; sales: number; demands: number
+  losses: number; transfers: number; inventories: number; stores: number
+}
+interface StepCtx { ctx: Ctx; step: Step; report: Report }
+
+const TS = Date.now()
+function check(step: Step, c: CheckResult) { step.checks.push(c) }
+function asString(x: unknown): string {
+  if (x == null) return ''
+  return typeof x === 'string' ? x : JSON.stringify(x)
+}
+
+async function bootstrap(ctx: Ctx): Promise<void> {
+  if (ctx.token) return
+  const api = makeClient()
+  ctx.email = `stage-seed-${TS}@food-market.local`
+  ctx.password = 'StageSeed12345!'
+  let r = await api.post('/api/auth/signup', {
+    email: ctx.email, password: ctx.password,
+    organizationName: `Seed ${TS}`, phone: '+77011190001', plan: 'start',
+  })
+  for (let i = 0; i < 5 && r.status === 429; i++) {
+    await new Promise(res => setTimeout(res, 15000))
+    r = await api.post('/api/auth/signup', {
+      email: ctx.email, password: ctx.password,
+      organizationName: `Seed ${TS}`, phone: '+77011190001', plan: 'start',
+    })
+  }
+  if (r.status !== 200) throw new Error(`signup: ${r.status} ${JSON.stringify(r.data)}`)
+  const sess = await login(ctx.email, ctx.password)
+  ctx.token = sess.accessToken
+}
+
+// ---------------------------------------------------------------------------
+
+export async function seed01_status_empty({ ctx, step, report }: StepCtx) {
+  ctx.ts = TS
+  await bootstrap(ctx)
+  const api = makeClient(ctx.token)
+  const r = await api.get('/api/admin/seed-demo/status')
+  check(step, { kind: 'api', description: 'GET /status → 200', ok: r.status === 200, detail: `${r.status}` })
+  ctx.initialSummary = r.data as SeedSummary
+  check(step, { kind: 'api', description: 'alreadySeeded = false', ok: r.data?.alreadySeeded === false, detail: `already=${r.data?.alreadySeeded}` })
+  check(step, { kind: 'api', description: 'products = 0', ok: r.data?.products === 0, detail: `products=${r.data?.products}` })
+}
+
+// ---------------------------------------------------------------------------
+
+export async function seed02_run({ ctx, step, report }: StepCtx) {
+  if (!ctx.token) { step.status = 'skip'; return }
+  const api = makeClient(ctx.token)
+  const r = await api.post('/api/admin/seed-demo', {})
+  check(step, { kind: 'api', description: 'POST /seed-demo → 200', ok: r.status === 200, detail: `${r.status} ${asString(r.data).slice(0, 250)}` })
+  if (r.status !== 200) return
+  const s = r.data as SeedSummary
+  check(step, { kind: 'api', description: 'alreadySeeded в ответе = false (только что заполнили)', ok: s.alreadySeeded === false, detail: `already=${s.alreadySeeded}` })
+  check(step, { kind: 'api', description: 'products = 50', ok: s.products === 50, detail: `products=${s.products}` })
+  check(step, { kind: 'api', description: 'groups = 5', ok: s.groups === 5, detail: `groups=${s.groups}` })
+  check(step, { kind: 'api', description: 'counterparties = 10', ok: s.counterparties === 10, detail: `cp=${s.counterparties}` })
+  check(step, { kind: 'api', description: 'supplies = 5, sales = 30', ok: s.supplies === 5 && s.sales === 30, detail: `sup=${s.supplies} sales=${s.sales}` })
+  check(step, { kind: 'api', description: 'demands=1, losses=1, transfers=1, inventories=1', ok: s.demands === 1 && s.losses === 1 && s.transfers === 1 && s.inventories === 1, detail: `dm=${s.demands} loss=${s.losses} tr=${s.transfers} inv=${s.inventories}` })
+  check(step, { kind: 'api', description: 'stores >= 2 (main + резерв для transfer)', ok: s.stores >= 2, detail: `stores=${s.stores}` })
+}
+
+// ---------------------------------------------------------------------------
+
+export async function seed03_status_after({ ctx, step, report }: StepCtx) {
+  if (!ctx.token) { step.status = 'skip'; return }
+  const api = makeClient(ctx.token)
+  const r = await api.get('/api/admin/seed-demo/status')
+  check(step, { kind: 'api', description: 'GET /status → alreadySeeded=true', ok: r.data?.alreadySeeded === true, detail: `already=${r.data?.alreadySeeded}` })
+  check(step, { kind: 'api', description: 'products = 50 в статусе', ok: r.data?.products === 50, detail: `products=${r.data?.products}` })
+}
+
+// ---------------------------------------------------------------------------
+
+export async function seed04_data_visible_via_normal_apis({ ctx, step, report }: StepCtx) {
+  if (!ctx.token) { step.status = 'skip'; return }
+  const api = makeClient(ctx.token)
+  const [prods, supplies, sales, demands, transfers, invs, cps] = await Promise.all([
+    api.get('/api/catalog/products?pageSize=200'),
+    api.get('/api/purchases/supplies?pageSize=50'),
+    api.get('/api/sales/retail?pageSize=50'),
+    api.get('/api/sales/demands?pageSize=50'),
+    api.get('/api/inventory/transfers?pageSize=50'),
+    api.get('/api/inventory/inventories?pageSize=50'),
+    api.get('/api/catalog/counterparties?pageSize=50'),
+  ])
+  check(step, { kind: 'api', description: 'products total >= 50', ok: (prods.data?.total ?? 0) >= 50, detail: `total=${prods.data?.total}` })
+  check(step, { kind: 'api', description: 'supplies total >= 5', ok: (supplies.data?.total ?? 0) >= 5, detail: `total=${supplies.data?.total}` })
+  check(step, { kind: 'api', description: 'retail sales total >= 30', ok: (sales.data?.total ?? 0) >= 30, detail: `total=${sales.data?.total}` })
+  check(step, { kind: 'api', description: 'demands total >= 1', ok: (demands.data?.total ?? 0) >= 1, detail: `total=${demands.data?.total}` })
+  check(step, { kind: 'api', description: 'transfers total >= 1', ok: (transfers.data?.total ?? 0) >= 1, detail: `total=${transfers.data?.total}` })
+  check(step, { kind: 'api', description: 'inventories total >= 1', ok: (invs.data?.total ?? 0) >= 1, detail: `total=${invs.data?.total}` })
+  check(step, { kind: 'api', description: 'counterparties total >= 10', ok: (cps.data?.total ?? 0) >= 10, detail: `total=${cps.data?.total}` })
+
+  // Проверка: все demo-товары начинаются с DEMO- в article
+  const demoCount = (prods.data?.items ?? []).filter((p: { article?: string }) => p.article?.startsWith('DEMO-')).length
+  check(step, { kind: 'api', description: 'Все 50 demo-товаров имеют article DEMO-...', ok: demoCount === 50, detail: `demoCount=${demoCount}` })
+}
+
+// ---------------------------------------------------------------------------
+
+export async function seed05_idempotent({ ctx, step, report }: StepCtx) {
+  if (!ctx.token) { step.status = 'skip'; return }
+  const api = makeClient(ctx.token)
+  const second = await api.post('/api/admin/seed-demo', {})
+  check(step, { kind: 'api', description: 'Повторный POST → 200, alreadySeeded=true', ok: second.status === 200 && second.data?.alreadySeeded === true, detail: `${second.status} already=${second.data?.alreadySeeded}` })
+  check(step, { kind: 'api', description: 'products = 50 (не дублировано)', ok: second.data?.products === 50, detail: `products=${second.data?.products}` })
+
+  const prods = await api.get('/api/catalog/products?pageSize=200')
+  check(step, { kind: 'api', description: 'products total всё ещё 50', ok: (prods.data?.total ?? 0) === 50, detail: `total=${prods.data?.total}` })
+}
diff --git a/tests/e2e/scenarios/stage-demo-seed.yml b/tests/e2e/scenarios/stage-demo-seed.yml
new file mode 100644
index 0000000..2fbc8b1
--- /dev/null
+++ b/tests/e2e/scenarios/stage-demo-seed.yml
@@ -0,0 +1,21 @@
+name: stage-demo-seed
+description: |
+  Demo seeder на test.admin.food-market.kz: создаёт org, проверяет
+  /status (alreadySeeded=false), запускает /run, проверяет что появились
+  товары/группы/контрагенты/документы; повторный /run идемпотентен.
+
+preconditions:
+  reset_db: false
+  smoke_login_super_admin: false
+
+steps:
+  - id: seed01_status_empty
+    title: Новый org → GET /api/admin/seed-demo/status → alreadySeeded=false, products=0
+  - id: seed02_run
+    title: POST /api/admin/seed-demo → 200, alreadySeeded=false, products>=50
+  - id: seed03_status_after
+    title: GET /status → alreadySeeded=true; products=50, supplies=5, sales=30, demands=1, losses=1, transfers=1, inventories=1, stores=2
+  - id: seed04_data_visible_via_normal_apis
+    title: GET /api/catalog/products, /api/purchases/supplies, /api/sales/retail, /api/inventory/transfers — содержат демо-записи
+  - id: seed05_idempotent
+    title: Повторный POST /api/admin/seed-demo → products всё ещё 50 (не дублировано)