diff --git a/apps/web-client-tpos-net/src/WebClientTpos.Client/Services/PosDataService.cs b/apps/web-client-tpos-net/src/WebClientTpos.Client/Services/PosDataService.cs
index 13e8cc49..53437e27 100644
--- a/apps/web-client-tpos-net/src/WebClientTpos.Client/Services/PosDataService.cs
+++ b/apps/web-client-tpos-net/src/WebClientTpos.Client/Services/PosDataService.cs
@@ -1,12 +1,16 @@
+using System.Net.Http.Headers;
 using System.Net.Http.Json;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
 namespace WebClientTpos.Client.Services;
 
+// EN: POS data service — attaches auth token for multi-tenant data isolation.
+// VI: POS data service — đính kèm auth token để cách ly dữ liệu multi-tenant.
 public class PosDataService
 {
     private readonly HttpClient _http;
+    private readonly AuthStateService _authState;
     private static readonly JsonSerializerOptions _jsonOptions = new()
     {
         PropertyNameCaseInsensitive = true,
@@ -14,7 +18,24 @@ public class PosDataService
         DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
     };
 
-    public PosDataService(HttpClient http) => _http = http;
+    public PosDataService(HttpClient http, AuthStateService authState)
+    {
+        _http = http;
+        _authState = authState;
+    }
+
+    /// <summary>
+    /// EN: Ensure Authorization header is set before each BFF call.
+    /// VI: Đảm bảo header Authorization được đặt trước mỗi BFF call.
+    /// </summary>
+    private void AttachToken()
+    {
+        if (!string.IsNullOrEmpty(_authState.Token))
+        {
+            _http.DefaultRequestHeaders.Authorization =
+                new AuthenticationHeaderValue("Bearer", _authState.Token);
+        }
+    }
 
     public record ShopInfo(Guid Id, string Name, string Slug, string? Description, string? Phone, string? Email, string? Category, string? Status);
     public record ProductInfo(Guid Id, string Name, decimal Price, string? Sku, string? Description, string? Category, int? DurationMinutes);
@@ -24,25 +45,25 @@ public class PosDataService
     public record StaffInfo(Guid Id, Guid? UserId, string? EmployeeCode, string? Phone, string? Email, DateTime? JoinedAt, DateTime? TerminatedAt, string? Role, string? Status, string? ShopName);
 
     public async Task<List<ShopInfo>> GetShopsAsync()
-        => await _http.GetFromJsonAsync<List<ShopInfo>>("api/bff/shops", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<ShopInfo>>("api/bff/shops", _jsonOptions) ?? new(); }
 
     public async Task<ShopInfo?> GetShopByIdAsync(Guid shopId)
-        => await _http.GetFromJsonAsync<ShopInfo>($"api/bff/shops/{shopId}", _jsonOptions);
+    { AttachToken(); return await _http.GetFromJsonAsync<ShopInfo>($"api/bff/shops/{shopId}", _jsonOptions); }
 
     public async Task<List<ProductInfo>> GetProductsAsync(Guid shopId)
-        => await _http.GetFromJsonAsync<List<ProductInfo>>($"api/bff/shops/{shopId}/products", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<ProductInfo>>($"api/bff/shops/{shopId}/products", _jsonOptions) ?? new(); }
 
     public async Task<List<CategoryInfo>> GetCategoriesAsync(Guid shopId)
-        => await _http.GetFromJsonAsync<List<CategoryInfo>>($"api/bff/shops/{shopId}/categories", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<CategoryInfo>>($"api/bff/shops/{shopId}/categories", _jsonOptions) ?? new(); }
 
     public async Task<List<TableInfo>> GetTablesAsync(Guid shopId)
-        => await _http.GetFromJsonAsync<List<TableInfo>>($"api/bff/shops/{shopId}/tables", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<TableInfo>>($"api/bff/shops/{shopId}/tables", _jsonOptions) ?? new(); }
 
     public async Task<List<AppointmentInfo>> GetAppointmentsAsync(Guid shopId)
-        => await _http.GetFromJsonAsync<List<AppointmentInfo>>($"api/bff/shops/{shopId}/appointments", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<AppointmentInfo>>($"api/bff/shops/{shopId}/appointments", _jsonOptions) ?? new(); }
 
     public async Task<List<StaffInfo>> GetStaffAsync()
-        => await _http.GetFromJsonAsync<List<StaffInfo>>("api/bff/staff", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<StaffInfo>>("api/bff/staff", _jsonOptions) ?? new(); }
 
     // ═══ ADMIN-LEVEL PRODUCT/CATEGORY METHODS ═══
 
@@ -57,24 +78,28 @@ public class PosDataService
 
     public async Task<List<AdminProductInfo>> GetAllProductsAsync(Guid? shopId = null)
     {
+        AttachToken();
         var url = shopId.HasValue ? $"api/bff/products?shopId={shopId}" : "api/bff/products";
         return await _http.GetFromJsonAsync<List<AdminProductInfo>>(url, _jsonOptions) ?? new();
     }
 
     public async Task<List<AdminCategoryInfo>> GetAllCategoriesAsync(Guid? shopId = null)
     {
+        AttachToken();
         var url = shopId.HasValue ? $"api/bff/categories?shopId={shopId}" : "api/bff/categories";
         return await _http.GetFromJsonAsync<List<AdminCategoryInfo>>(url, _jsonOptions) ?? new();
     }
 
     public async Task<bool> CreateProductAsync(CreateProductRequest req)
     {
+        AttachToken();
         var resp = await _http.PostAsJsonAsync("api/bff/products", req, _jsonOptions);
         return resp.IsSuccessStatusCode;
     }
 
     public async Task<bool> DeleteProductAsync(Guid productId)
     {
+        AttachToken();
         var resp = await _http.DeleteAsync($"api/bff/products/{productId}");
         return resp.IsSuccessStatusCode;
     }
@@ -86,6 +111,7 @@ public class PosDataService
 
     public async Task<List<InventoryItemInfo>> GetInventoryAsync(Guid? shopId = null)
     {
+        AttachToken();
         var url = shopId.HasValue ? $"api/bff/inventory?shopId={shopId}" : "api/bff/inventory";
         return await _http.GetFromJsonAsync<List<InventoryItemInfo>>(url, _jsonOptions) ?? new();
     }
@@ -96,7 +122,7 @@ public class PosDataService
         int CurrentLevel, int TotalExpEarned, DateTime CreatedAt, string? LevelName);
 
     public async Task<List<MemberInfo>> GetMembersAsync()
-        => await _http.GetFromJsonAsync<List<MemberInfo>>("api/bff/members", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<MemberInfo>>("api/bff/members", _jsonOptions) ?? new(); }
 
     // ═══ STAFF CREATE ═══
 
@@ -104,6 +130,7 @@ public class PosDataService
 
     public async Task<bool> CreateStaffAsync(CreateStaffRequest req)
     {
+        AttachToken();
         var resp = await _http.PostAsJsonAsync("api/bff/staff", req, _jsonOptions);
         return resp.IsSuccessStatusCode;
     }
@@ -115,10 +142,11 @@ public class PosDataService
         string? EmployeeCode, string? Role, string? Phone);
 
     public async Task<List<StaffRoleInfo>> GetStaffRolesAsync()
-        => await _http.GetFromJsonAsync<List<StaffRoleInfo>>("api/bff/staff/roles", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<StaffRoleInfo>>("api/bff/staff/roles", _jsonOptions) ?? new(); }
 
     public async Task<List<ScheduleInfo>> GetStaffSchedulesAsync(Guid? shopId = null)
     {
+        AttachToken();
         var url = shopId.HasValue ? $"api/bff/staff/schedules?shopId={shopId}" : "api/bff/staff/schedules";
         return await _http.GetFromJsonAsync<List<ScheduleInfo>>(url, _jsonOptions) ?? new();
     }
@@ -129,6 +157,7 @@ public class PosDataService
 
     public async Task<List<OrderInfo>> GetOrdersAsync(Guid? shopId = null)
     {
+        AttachToken();
         var url = shopId.HasValue ? $"api/bff/orders?shopId={shopId}" : "api/bff/orders";
         return await _http.GetFromJsonAsync<List<OrderInfo>>(url, _jsonOptions) ?? new();
     }
@@ -139,17 +168,17 @@ public class PosDataService
     public record WalletTxnInfo(Guid Id, Guid WalletId, decimal Amount, string? Description, DateTime CreatedAt, string? ItemName);
 
     public async Task<List<WalletInfo>> GetWalletsAsync()
-        => await _http.GetFromJsonAsync<List<WalletInfo>>("api/bff/wallets", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<WalletInfo>>("api/bff/wallets", _jsonOptions) ?? new(); }
 
     public async Task<List<WalletTxnInfo>> GetWalletTransactionsAsync(int limit = 50)
-        => await _http.GetFromJsonAsync<List<WalletTxnInfo>>($"api/bff/wallet/transactions?limit={limit}", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<WalletTxnInfo>>($"api/bff/wallet/transactions?limit={limit}", _jsonOptions) ?? new(); }
 
     // ═══ DEVICES ═══
 
     public record DeviceInfo(Guid Id, string? DeviceToken, string? Platform, bool IsActive, DateTime CreatedAt, string? StaffCode);
 
     public async Task<List<DeviceInfo>> GetDevicesAsync()
-        => await _http.GetFromJsonAsync<List<DeviceInfo>>("api/bff/devices", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<DeviceInfo>>("api/bff/devices", _jsonOptions) ?? new(); }
 
     // ═══ PROMOTIONS ═══
 
@@ -157,7 +186,7 @@ public class PosDataService
         bool IsActive, string? DiscountType, decimal? DiscountValue, int VoucherCount, int RedemptionCount);
 
     public async Task<List<PromotionInfo>> GetPromotionsAsync()
-        => await _http.GetFromJsonAsync<List<PromotionInfo>>("api/bff/promotions", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<PromotionInfo>>("api/bff/promotions", _jsonOptions) ?? new(); }
 
     // ═══ INVENTORY TRANSACTIONS ═══
 
@@ -165,6 +194,7 @@ public class PosDataService
 
     public async Task<List<InventoryTxnInfo>> GetInventoryTransactionsAsync(Guid? shopId = null)
     {
+        AttachToken();
         var url = shopId.HasValue ? $"api/bff/inventory/transactions?shopId={shopId}" : "api/bff/inventory/transactions";
         return await _http.GetFromJsonAsync<List<InventoryTxnInfo>>(url, _jsonOptions) ?? new();
     }
@@ -174,12 +204,12 @@ public class PosDataService
     public record LevelDefinitionInfo(Guid Id, int Level, string Name, int MinExp, int MaxExp, int MemberCount);
 
     public async Task<List<LevelDefinitionInfo>> GetMembershipLevelsAsync()
-        => await _http.GetFromJsonAsync<List<LevelDefinitionInfo>>("api/bff/membership/levels", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<LevelDefinitionInfo>>("api/bff/membership/levels", _jsonOptions) ?? new(); }
 
     // ═══ SHOP STATS (aggregated per-shop) ═══
 
     public record ShopStatsInfo(Guid ShopId, int ProductCount, int OrderCount, int StaffCount, decimal Revenue);
 
     public async Task<List<ShopStatsInfo>> GetShopStatsAsync()
-        => await _http.GetFromJsonAsync<List<ShopStatsInfo>>("api/bff/shops/stats", _jsonOptions) ?? new();
+    { AttachToken(); return await _http.GetFromJsonAsync<List<ShopStatsInfo>>("api/bff/shops/stats", _jsonOptions) ?? new(); }
 }
diff --git a/apps/web-client-tpos-net/src/WebClientTpos.Server/Controllers/BffDataController.cs b/apps/web-client-tpos-net/src/WebClientTpos.Server/Controllers/BffDataController.cs
index 9df71c72..cd2bcc5b 100644
--- a/apps/web-client-tpos-net/src/WebClientTpos.Server/Controllers/BffDataController.cs
+++ b/apps/web-client-tpos-net/src/WebClientTpos.Server/Controllers/BffDataController.cs
@@ -1,9 +1,16 @@
 using Microsoft.AspNetCore.Mvc;
 using Npgsql;
 using Dapper;
+using System.IdentityModel.Tokens.Jwt;
 
 namespace WebClientTpos.Server.Controllers;
 
+// EN: BFF controller with multi-tenant data isolation.
+//     All queries are scoped to the current user's merchant.
+//     JWT token is parsed manually from Authorization header (no middleware dependency).
+// VI: BFF controller với cách ly dữ liệu multi-tenant.
+//     Tất cả queries đều lọc theo merchant của user hiện tại.
+//     JWT token được parse thủ công từ header Authorization (không phụ thuộc middleware).
 [ApiController]
 [Route("api/bff")]
 public class BffDataController : ControllerBase
@@ -18,9 +25,72 @@ public class BffDataController : ControllerBase
     private static string ConnStr(string db) =>
         $"Host={_dbHost};Port={_dbPort};Database={db};Username={_dbUser};Password={_dbPass}";
 
+    // ═══ TENANT RESOLUTION HELPERS ═══
+
+    /// <summary>
+    /// EN: Extract user ID from JWT token in Authorization header.
+    ///     Parses the token manually without middleware validation.
+    /// VI: Trích xuất user ID từ JWT token trong header Authorization.
+    ///     Parse token thủ công không cần middleware validation.
+    /// </summary>
+    private Guid? GetUserIdFromToken()
+    {
+        var authHeader = Request.Headers["Authorization"].FirstOrDefault();
+        if (string.IsNullOrEmpty(authHeader) || !authHeader.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
+            return null;
+
+        var tokenStr = authHeader["Bearer ".Length..].Trim();
+        try
+        {
+            var handler = new JwtSecurityTokenHandler();
+            var jwt = handler.ReadJwtToken(tokenStr);
+            var sub = jwt.Claims.FirstOrDefault(c => c.Type == "sub")?.Value;
+            if (!string.IsNullOrEmpty(sub) && Guid.TryParse(sub, out var userId))
+                return userId;
+        }
+        catch { /* Invalid token — return null */ }
+
+        return null;
+    }
+
+    /// <summary>
+    /// EN: Extract current user's merchant ID from JWT → merchants table.
+    /// VI: Lấy merchant ID của user hiện tại từ JWT → bảng merchants.
+    /// </summary>
+    private async Task<Guid?> GetCurrentMerchantIdAsync()
+    {
+        var userId = GetUserIdFromToken();
+        if (userId == null)
+            return null;
+
+        await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
+        return await conn.QueryFirstOrDefaultAsync<Guid?>(
+            "SELECT id FROM merchants WHERE user_id = @UserId AND is_deleted = false",
+            new { UserId = userId });
+    }
+
+    /// <summary>
+    /// EN: Get list of shop IDs owned by the current merchant.
+    /// VI: Lấy danh sách shop IDs thuộc sở hữu của merchant hiện tại.
+    /// </summary>
+    private async Task<List<Guid>> GetMyShopIdsAsync(Guid merchantId)
+    {
+        await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
+        var ids = await conn.QueryAsync<Guid>(
+            "SELECT id FROM shops WHERE merchant_id = @MerchantId AND is_deleted = false",
+            new { MerchantId = merchantId });
+        return ids.ToList();
+    }
+
+    // ═══ SHOP ENDPOINTS ═══
+
     [HttpGet("shops")]
     public async Task<IActionResult> GetShops()
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>()); // EN: No merchant → no shops / VI: Không có merchant → không có shops
+
         await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
         var shops = await conn.QueryAsync<dynamic>(
             @"SELECT s.id, s.name, s.slug, s.description, s.phone, s.email,
@@ -29,14 +99,19 @@ public class BffDataController : ControllerBase
               FROM shops s
               JOIN business_categories bc ON s.category_id = bc.id
               JOIN shop_statuses st ON s.status_id = st.id
-              WHERE s.is_deleted = false
-              ORDER BY s.name");
+              WHERE s.merchant_id = @MerchantId AND s.is_deleted = false
+              ORDER BY s.name",
+            new { MerchantId = merchantId });
         return Ok(shops);
     }
 
     [HttpGet("shops/{shopId:guid}")]
     public async Task<IActionResult> GetShopById(Guid shopId)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return NotFound(new { message = "Shop not found" });
+
         await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
         var shop = await conn.QueryFirstOrDefaultAsync<dynamic>(
             @"SELECT s.id, s.name, s.slug, s.description, s.phone, s.email,
@@ -45,8 +120,8 @@ public class BffDataController : ControllerBase
               FROM shops s
               JOIN business_categories bc ON s.category_id = bc.id
               JOIN shop_statuses st ON s.status_id = st.id
-              WHERE s.id = @ShopId AND s.is_deleted = false",
-            new { ShopId = shopId });
+              WHERE s.id = @ShopId AND s.merchant_id = @MerchantId AND s.is_deleted = false",
+            new { ShopId = shopId, MerchantId = merchantId });
 
         if (shop == null)
             return NotFound(new { message = "Shop not found" });
@@ -57,6 +132,10 @@ public class BffDataController : ControllerBase
     [HttpGet("staff")]
     public async Task<IActionResult> GetStaff()
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
         await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
         var staff = await conn.QueryAsync<dynamic>(
             @"SELECT ms.id, ms.user_id, ms.employee_code, ms.phone, ms.email,
@@ -68,7 +147,9 @@ public class BffDataController : ControllerBase
               JOIN staff_statuses ss ON ms.status_id = ss.id
               LEFT JOIN shop_members sm ON sm.staff_id = ms.id
               LEFT JOIN shops s ON sm.shop_id = s.id
-              ORDER BY ms.joined_at DESC");
+              WHERE ms.merchant_id = @MerchantId
+              ORDER BY ms.joined_at DESC",
+            new { MerchantId = merchantId });
         return Ok(staff);
     }
 
@@ -150,54 +231,88 @@ public class BffDataController : ControllerBase
         return Ok(resources);
     }
 
-    // ═══ ADMIN-LEVEL PRODUCT ENDPOINTS ═══
+    // ═══ MERCHANT-SCOPED PRODUCT ENDPOINTS ═══
 
     /// <summary>
-    /// EN: Get all products across all shops (admin level).
-    /// VI: Lấy tất cả sản phẩm trên tất cả cửa hàng (cấp admin).
+    /// EN: Get products belonging to the current merchant's shops.
+    /// VI: Lấy sản phẩm thuộc các cửa hàng của merchant hiện tại.
     /// </summary>
     [HttpGet("products")]
     public async Task<IActionResult> GetAllProducts([FromQuery] Guid? shopId = null)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Any())
+            return Ok(Array.Empty<object>());
+
+        // EN: If shopId specified, verify ownership / VI: Nếu có shopId, kiểm tra quyền sở hữu
+        if (shopId.HasValue && !myShopIds.Contains(shopId.Value))
+            return Ok(Array.Empty<object>());
+
+        var targetShopIds = shopId.HasValue ? new List<Guid> { shopId.Value } : myShopIds;
+
         await using var conn = new NpgsqlConnection(ConnStr("catalog_service"));
-        var sql = @"SELECT p.id, p.name, p.price, p.sku, p.description, p.image_url,
-                           p.is_active, pt.name as type, p.shop_id, p.created_at,
-                           '' as category_name
-                    FROM products p
-                    JOIN product_types pt ON p.type_id = pt.id";
-        if (shopId.HasValue)
-            sql += " WHERE p.shop_id = @ShopId";
-        sql += " ORDER BY p.name";
-        var products = await conn.QueryAsync<dynamic>(sql, new { ShopId = shopId });
+        var products = await conn.QueryAsync<dynamic>(
+            @"SELECT p.id, p.name, p.price, p.sku, p.description, p.image_url,
+                     p.is_active, pt.name as type, p.shop_id, p.created_at,
+                     '' as category_name
+              FROM products p
+              JOIN product_types pt ON p.type_id = pt.id
+              WHERE p.shop_id = ANY(@ShopIds)
+              ORDER BY p.name",
+            new { ShopIds = targetShopIds.ToArray() });
         return Ok(products);
     }
 
     /// <summary>
-    /// EN: Get all categories across all shops (admin level).
-    /// VI: Lấy tất cả danh mục trên tất cả cửa hàng (cấp admin).
+    /// EN: Get categories belonging to the current merchant's shops.
+    /// VI: Lấy danh mục thuộc các cửa hàng của merchant hiện tại.
     /// </summary>
     [HttpGet("categories")]
     public async Task<IActionResult> GetAllCategories([FromQuery] Guid? shopId = null)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Any())
+            return Ok(Array.Empty<object>());
+
+        if (shopId.HasValue && !myShopIds.Contains(shopId.Value))
+            return Ok(Array.Empty<object>());
+
+        var targetShopIds = shopId.HasValue ? new List<Guid> { shopId.Value } : myShopIds;
+
         await using var conn = new NpgsqlConnection(ConnStr("catalog_service"));
-        var sql = @"SELECT id, name, description, display_order, shop_id, parent_id, is_active
-                    FROM categories WHERE is_active = true";
-        if (shopId.HasValue)
-            sql += " AND shop_id = @ShopId";
-        sql += " ORDER BY display_order, name";
-        var categories = await conn.QueryAsync<dynamic>(sql, new { ShopId = shopId });
+        var categories = await conn.QueryAsync<dynamic>(
+            @"SELECT id, name, description, display_order, shop_id, parent_id, is_active
+              FROM categories
+              WHERE is_active = true AND shop_id = ANY(@ShopIds)
+              ORDER BY display_order, name",
+            new { ShopIds = targetShopIds.ToArray() });
         return Ok(categories);
     }
 
     /// <summary>
-    /// EN: Create a product via BFF (writes directly to catalog DB).
-    /// VI: Tạo sản phẩm qua BFF (ghi trực tiếp vào catalog DB).
+    /// EN: Create a product — validates shop ownership first.
+    /// VI: Tạo sản phẩm — kiểm tra quyền sở hữu shop trước.
     /// </summary>
     [HttpPost("products")]
     public async Task<IActionResult> CreateProduct([FromBody] CreateProductRequest req)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Forbid();
+
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Contains(req.ShopId))
+            return Forbid(); // EN: Cannot create product in another merchant's shop
+
         var id = Guid.NewGuid();
-        // EN: Map type string to type_id / VI: Chuyển type string sang type_id
         var typeId = (req.Type ?? "PreparedFood") switch
         {
             "Physical" => 1,
@@ -214,16 +329,24 @@ public class BffDataController : ControllerBase
     }
 
     /// <summary>
-    /// EN: Delete (deactivate) a product.
-    /// VI: Xóa (vô hiệu hóa) sản phẩm.
+    /// EN: Delete (deactivate) a product — validates ownership first.
+    /// VI: Xóa (vô hiệu hóa) sản phẩm — kiểm tra quyền sở hữu trước.
     /// </summary>
     [HttpDelete("products/{productId:guid}")]
     public async Task<IActionResult> DeleteProduct(Guid productId)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Forbid();
+
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+
         await using var conn = new NpgsqlConnection(ConnStr("catalog_service"));
+        // EN: Only delete if product belongs to one of merchant's shops
+        // VI: Chỉ xóa nếu sản phẩm thuộc shop của merchant
         await conn.ExecuteAsync(
-            "UPDATE products SET is_active = false WHERE id = @Id",
-            new { Id = productId });
+            "UPDATE products SET is_active = false WHERE id = @Id AND shop_id = ANY(@ShopIds)",
+            new { Id = productId, ShopIds = myShopIds.ToArray() });
         return NoContent();
     }
 
@@ -236,18 +359,33 @@ public class BffDataController : ControllerBase
     [HttpGet("inventory")]
     public async Task<IActionResult> GetInventory([FromQuery] Guid? shopId = null)
     {
-        await using var conn = new NpgsqlConnection(ConnStr("inventory_service"));
-        var sql = @"SELECT id, product_id, shop_id, quantity, reorder_level, reserved_quantity, updated_at
-                    FROM inventory_items";
-        if (shopId.HasValue)
-            sql += " WHERE shop_id = @ShopId";
-        sql += " ORDER BY quantity ASC";
-        var items = await conn.QueryAsync<dynamic>(sql, new { ShopId = shopId });
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
 
-        // EN: Enrich with product names from catalog_service
-        // VI: Bổ sung tên sản phẩm từ catalog_service
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Any())
+            return Ok(Array.Empty<object>());
+
+        if (shopId.HasValue && !myShopIds.Contains(shopId.Value))
+            return Ok(Array.Empty<object>());
+
+        var targetShopIds = shopId.HasValue ? new List<Guid> { shopId.Value } : myShopIds;
+
+        await using var conn = new NpgsqlConnection(ConnStr("inventory_service"));
+        var items = await conn.QueryAsync<dynamic>(
+            @"SELECT id, product_id, shop_id, quantity, reorder_level, reserved_quantity, updated_at
+              FROM inventory_items
+              WHERE shop_id = ANY(@ShopIds)
+              ORDER BY quantity ASC",
+            new { ShopIds = targetShopIds.ToArray() });
+
+        // EN: Enrich with product names from catalog_service (scoped)
+        // VI: Bổ sung tên sản phẩm từ catalog_service (đã lọc)
         await using var catConn = new NpgsqlConnection(ConnStr("catalog_service"));
-        var products = (await catConn.QueryAsync<dynamic>("SELECT id, name FROM products")).ToList();
+        var products = (await catConn.QueryAsync<dynamic>(
+            "SELECT id, name FROM products WHERE shop_id = ANY(@ShopIds)",
+            new { ShopIds = targetShopIds.ToArray() })).ToList();
         var prodMap = products.ToDictionary(p => (Guid)p.id, p => (string)p.name);
 
         var result = items.Select(i => new
@@ -282,19 +420,22 @@ public class BffDataController : ControllerBase
     // ═══ STAFF CREATE ENDPOINT ═══
 
     /// <summary>
-    /// EN: Create a staff member.
-    /// VI: Tạo nhân viên mới.
+    /// EN: Create a staff member — validates merchant ownership.
+    /// VI: Tạo nhân viên mới — kiểm tra quyền sở hữu merchant.
     /// </summary>
     [HttpPost("staff")]
     public async Task<IActionResult> CreateStaff([FromBody] CreateStaffRequest req)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null || merchantId.Value != req.MerchantId)
+            return Forbid(); // EN: Cannot create staff for another merchant
+
         var id = Guid.NewGuid();
         await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
 
-        // EN: Get default role and status IDs / VI: Lấy ID vai trò và trạng thái mặc định
         var roleId = await conn.QueryFirstOrDefaultAsync<int>(
             "SELECT id FROM staff_roles WHERE name = @Role", new { req.Role }) ;
-        if (roleId == 0) roleId = 1; // default to first role
+        if (roleId == 0) roleId = 1;
 
         var statusId = await conn.QueryFirstOrDefaultAsync<int>(
             "SELECT id FROM staff_statuses WHERE name = 'Active'");
@@ -344,41 +485,68 @@ public class BffDataController : ControllerBase
     [HttpGet("orders")]
     public async Task<IActionResult> GetOrders([FromQuery] Guid? shopId = null)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Any())
+            return Ok(Array.Empty<object>());
+
+        if (shopId.HasValue && !myShopIds.Contains(shopId.Value))
+            return Ok(Array.Empty<object>());
+
+        var targetShopIds = shopId.HasValue ? new List<Guid> { shopId.Value } : myShopIds;
+
         await using var conn = new NpgsqlConnection(ConnStr("order_service"));
-        var sql = @"SELECT o.id, o.shop_id, o.total_amount, o.status_id, o.created_at,
-                           os.name as status
-                    FROM orders o
-                    JOIN order_statuses os ON o.status_id = os.id";
-        if (shopId.HasValue) sql += " WHERE o.shop_id = @ShopId";
-        sql += " ORDER BY o.created_at DESC LIMIT 200";
-        var orders = await conn.QueryAsync<dynamic>(sql, new { ShopId = shopId });
+        var orders = await conn.QueryAsync<dynamic>(
+            @"SELECT o.id, o.shop_id, o.total_amount, o.status_id, o.created_at,
+                     os.name as status
+              FROM orders o
+              JOIN order_statuses os ON o.status_id = os.id
+              WHERE o.shop_id = ANY(@ShopIds)
+              ORDER BY o.created_at DESC LIMIT 200",
+            new { ShopIds = targetShopIds.ToArray() });
         return Ok(orders);
     }
 
-    // ═══ WALLET/FINANCE ═══
+    // ═══ WALLET/FINANCE (scoped by merchant owner_id) ═══
     [HttpGet("wallets")]
     public async Task<IActionResult> GetWallets()
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
         await using var conn = new NpgsqlConnection(ConnStr("wallet_service"));
         var wallets = await conn.QueryAsync<dynamic>(
             @"SELECT w.id, w.balance, w.currency, w.owner_id, w.created_at,
                      (SELECT COALESCE(SUM(amount),0) FROM wallet_transactions wt WHERE wt.wallet_id = w.id AND wt.amount > 0) as total_income,
                      (SELECT COALESCE(SUM(ABS(amount)),0) FROM wallet_transactions wt WHERE wt.wallet_id = w.id AND wt.amount < 0) as total_expense
-              FROM wallets w ORDER BY w.created_at DESC");
+              FROM wallets w
+              WHERE w.owner_id = @MerchantId::text
+              ORDER BY w.created_at DESC",
+            new { MerchantId = merchantId });
         return Ok(wallets);
     }
 
     [HttpGet("wallet/transactions")]
     public async Task<IActionResult> GetWalletTransactions([FromQuery] int limit = 50)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
         await using var conn = new NpgsqlConnection(ConnStr("wallet_service"));
         var txns = await conn.QueryAsync<dynamic>(
             @"SELECT wt.id, wt.wallet_id, wt.amount, wt.description, wt.created_at,
                      wi.name as item_name
               FROM wallet_transactions wt
+              JOIN wallets w ON wt.wallet_id = w.id
               LEFT JOIN wallet_items wi ON wt.reference_id = wi.id
+              WHERE w.owner_id = @MerchantId::text
               ORDER BY wt.created_at DESC LIMIT @Limit",
-            new { Limit = limit });
+            new { MerchantId = merchantId, Limit = limit });
         return Ok(txns);
     }
 
@@ -413,15 +581,29 @@ public class BffDataController : ControllerBase
     [HttpGet("inventory/transactions")]
     public async Task<IActionResult> GetInventoryTransactions([FromQuery] Guid? shopId = null)
     {
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
+
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Any())
+            return Ok(Array.Empty<object>());
+
+        if (shopId.HasValue && !myShopIds.Contains(shopId.Value))
+            return Ok(Array.Empty<object>());
+
+        var targetShopIds = shopId.HasValue ? new List<Guid> { shopId.Value } : myShopIds;
+
         await using var conn = new NpgsqlConnection(ConnStr("inventory_service"));
-        var sql = @"SELECT it.id, it.inventory_item_id, it.quantity_change, it.reason, it.created_at,
-                           tt.name as transaction_type
-                    FROM inventory_transactions it
-                    JOIN transaction_types tt ON it.type_id = tt.id";
-        if (shopId.HasValue)
-            sql += @" JOIN inventory_items ii ON it.inventory_item_id = ii.id WHERE ii.shop_id = @ShopId";
-        sql += " ORDER BY it.created_at DESC LIMIT 100";
-        var txns = await conn.QueryAsync<dynamic>(sql, new { ShopId = shopId });
+        var txns = await conn.QueryAsync<dynamic>(
+            @"SELECT it.id, it.inventory_item_id, it.quantity_change, it.reason, it.created_at,
+                     tt.name as transaction_type
+              FROM inventory_transactions it
+              JOIN transaction_types tt ON it.type_id = tt.id
+              JOIN inventory_items ii ON it.inventory_item_id = ii.id
+              WHERE ii.shop_id = ANY(@ShopIds)
+              ORDER BY it.created_at DESC LIMIT 100",
+            new { ShopIds = targetShopIds.ToArray() });
         return Ok(txns);
     }
 
@@ -437,38 +619,47 @@ public class BffDataController : ControllerBase
         return Ok(levels);
     }
 
-    // ═══ SHOP STATS (aggregated per-shop counts) ═══
+    // ═══ SHOP STATS (merchant-scoped per-shop counts) ═══
 
     /// <summary>
-    /// EN: Get aggregated stats per shop — product count, order count, staff count, revenue.
-    /// VI: Lấy thống kê tổng hợp theo shop — số sản phẩm, đơn hàng, nhân viên, doanh thu.
+    /// EN: Get aggregated stats per shop — scoped to current merchant.
+    /// VI: Lấy thống kê tổng hợp theo shop — lọc theo merchant hiện tại.
     /// </summary>
     [HttpGet("shops/stats")]
     public async Task<IActionResult> GetShopStats()
     {
-        // EN: Collect stats from multiple service databases
-        // VI: Thu thập stats từ nhiều database dịch vụ
+        var merchantId = await GetCurrentMerchantIdAsync();
+        if (merchantId == null)
+            return Ok(Array.Empty<object>());
 
-        // Products per shop
+        var myShopIds = await GetMyShopIdsAsync(merchantId.Value);
+        if (!myShopIds.Any())
+            return Ok(Array.Empty<object>());
+
+        var shopIdsArray = myShopIds.ToArray();
+
+        // Products per shop (scoped)
         Dictionary<Guid, int> productCounts = new();
         try
         {
             await using var catConn = new NpgsqlConnection(ConnStr("catalog_service"));
             var prodStats = await catConn.QueryAsync<dynamic>(
-                "SELECT shop_id, COUNT(*) as cnt FROM products WHERE is_active = true GROUP BY shop_id");
+                "SELECT shop_id, COUNT(*) as cnt FROM products WHERE is_active = true AND shop_id = ANY(@ShopIds) GROUP BY shop_id",
+                new { ShopIds = shopIdsArray });
             foreach (var ps in prodStats)
                 productCounts[(Guid)ps.shop_id] = (int)(long)ps.cnt;
         }
         catch { /* catalog_service may not have data yet */ }
 
-        // Orders per shop + revenue
+        // Orders per shop + revenue (scoped)
         Dictionary<Guid, int> orderCounts = new();
         Dictionary<Guid, decimal> revenues = new();
         try
         {
             await using var orderConn = new NpgsqlConnection(ConnStr("order_service"));
             var orderStats = await orderConn.QueryAsync<dynamic>(
-                "SELECT shop_id, COUNT(*) as cnt, COALESCE(SUM(total_amount), 0) as revenue FROM orders GROUP BY shop_id");
+                "SELECT shop_id, COUNT(*) as cnt, COALESCE(SUM(total_amount), 0) as revenue FROM orders WHERE shop_id = ANY(@ShopIds) GROUP BY shop_id",
+                new { ShopIds = shopIdsArray });
             foreach (var os in orderStats)
             {
                 orderCounts[(Guid)os.shop_id] = (int)(long)os.cnt;
@@ -477,7 +668,7 @@ public class BffDataController : ControllerBase
         }
         catch { /* order_service may not have data yet */ }
 
-        // Staff per shop (via shop_members join)
+        // Staff per shop (scoped)
         Dictionary<Guid, int> staffCounts = new();
         try
         {
@@ -487,29 +678,21 @@ public class BffDataController : ControllerBase
                   FROM shop_members sm
                   JOIN merchant_staff ms ON sm.staff_id = ms.id
                   JOIN staff_statuses ss ON ms.status_id = ss.id
-                  WHERE ss.name = 'Active'
-                  GROUP BY sm.shop_id");
+                  WHERE ss.name = 'Active' AND sm.shop_id = ANY(@ShopIds)
+                  GROUP BY sm.shop_id",
+                new { ShopIds = shopIdsArray });
             foreach (var ss in staffStats)
                 staffCounts[(Guid)ss.shop_id] = (int)(long)ss.cnt;
         }
         catch { /* merchant_service may not have data yet */ }
 
-        // EN: Get all shops and merge stats / VI: Lấy shops rồi merge stats
-        await using var conn = new NpgsqlConnection(ConnStr("merchant_service"));
-        var shops = await conn.QueryAsync<dynamic>(
-            "SELECT id FROM shops WHERE is_deleted = false");
-
-        var result = shops.Select(s =>
+        var result = myShopIds.Select(shopId => new
         {
-            var shopId = (Guid)s.id;
-            return new
-            {
-                shop_id = shopId,
-                product_count = productCounts.GetValueOrDefault(shopId, 0),
-                order_count = orderCounts.GetValueOrDefault(shopId, 0),
-                staff_count = staffCounts.GetValueOrDefault(shopId, 0),
-                revenue = revenues.GetValueOrDefault(shopId, 0m)
-            };
+            shop_id = shopId,
+            product_count = productCounts.GetValueOrDefault(shopId, 0),
+            order_count = orderCounts.GetValueOrDefault(shopId, 0),
+            staff_count = staffCounts.GetValueOrDefault(shopId, 0),
+            revenue = revenues.GetValueOrDefault(shopId, 0m)
         });
 
         return Ok(result);
diff --git a/apps/web-client-tpos-net/src/WebClientTpos.Server/WebClientTpos.Server.csproj b/apps/web-client-tpos-net/src/WebClientTpos.Server/WebClientTpos.Server.csproj
index d89c0221..bdba6648 100644
--- a/apps/web-client-tpos-net/src/WebClientTpos.Server/WebClientTpos.Server.csproj
+++ b/apps/web-client-tpos-net/src/WebClientTpos.Server/WebClientTpos.Server.csproj
@@ -8,6 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="Dapper" Version="2.1.66" />
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="10.0.0-preview.1.25120.3" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.1" />
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Server" Version="10.0.1" />
     <PackageReference Include="Npgsql" Version="9.0.3" />