diff --git a/.claude/settings.local.json b/.claude/settings.local.json
index fd77ad4b..35b4e8d2 100644
--- a/.claude/settings.local.json
+++ b/.claude/settings.local.json
@@ -85,7 +85,8 @@
       "PowerShell($xml = Get-ChildItem \"$env:USERPROFILE\\\\.nuget\\\\packages\\\\devexpress.blazor\" -Recurse -Filter \"DevExpress.Blazor.xml\" -ErrorAction SilentlyContinue | Select-Object -Last 1; if \\($xml\\) { $xml.FullName; Select-String -Path $xml.FullName -Pattern \"MessageBoxOptions\\\\.\\(BodyTemplate|CssClass|Text|Title\\)\" | Select-Object -First 8 | ForEach-Object { $_.Line.Trim\\(\\).Substring\\(0, [Math]::Min\\(120, $_.Line.Trim\\(\\).Length\\)\\) } } else { \"DevExpress.Blazor.xml nem talalhato a NuGet cache-ben\" })",
       "PowerShell($lib = Get-ChildItem \"$env:USERPROFILE\\\\.nuget\\\\packages\\\\devexpress.blazor\" -Directory | Sort-Object Name | Select-Object -Last 1; \"Verzio: $\\($lib.Name\\)\"; $dll = Get-ChildItem $lib.FullName -Recurse -Filter \"DevExpress.Blazor.dll\" | Select-Object -First 1; $asm = [System.Reflection.Assembly]::LoadFile\\($dll.FullName\\); $t = $asm.GetType\\(\"DevExpress.Blazor.MessageBoxOptions\"\\); if \\($t\\) { $t.GetProperties\\(\\) | Select-Object -ExpandProperty Name } else { \"MessageBoxOptions tipus nem talalhato\" })",
       "PowerShell($dll = Get-ChildItem \"$env:USERPROFILE\\\\.nuget\\\\packages\\\\devexpress.blazor\\\\25.1.5\" -Recurse -Filter \"DevExpress.Blazor.dll\" | Select-Object -First 1; $dll.FullName; $bytes = [System.IO.File]::ReadAllBytes\\($dll.FullName\\); $text = [System.Text.Encoding]::ASCII.GetString\\($bytes\\); @\\(\"BodyTemplate\",\"CssClass\",\"MessageBoxOptions\"\\) | ForEach-Object { \"$\\($_\\): $\\($text.Contains\\($_\\)\\)\" })",
-      "PowerShell($dll = \"C:\\\\Users\\\\Fullepi\\\\.nuget\\\\packages\\\\devexpress.blazor\\\\25.1.5\\\\lib\\\\net8.0\\\\DevExpress.Blazor.v25.1.dll\"; $bytes = [System.IO.File]::ReadAllBytes\\($dll\\); $text = [System.Text.Encoding]::ASCII.GetString\\($bytes\\); @\\(\"BodyTemplate\",\"get_CssClass\",\"MessageBoxOptions\",\"TitleTemplate\"\\) | ForEach-Object { \"$\\($_\\): $\\($text.Contains\\($_\\)\\)\" })"
+      "PowerShell($dll = \"C:\\\\Users\\\\Fullepi\\\\.nuget\\\\packages\\\\devexpress.blazor\\\\25.1.5\\\\lib\\\\net8.0\\\\DevExpress.Blazor.v25.1.dll\"; $bytes = [System.IO.File]::ReadAllBytes\\($dll\\); $text = [System.Text.Encoding]::ASCII.GetString\\($bytes\\); @\\(\"BodyTemplate\",\"get_CssClass\",\"MessageBoxOptions\",\"TitleTemplate\"\\) | ForEach-Object { \"$\\($_\\): $\\($text.Contains\\($_\\)\\)\" })",
+      "PowerShell(dotnet test \"H:\\\\Applications\\\\Aycode\\\\Source\\\\AyCode.Core\\\\AyCode.Services.Tests\\\\AyCode.Services.Tests.csproj\" --filter \"FullyQualifiedName~EkaerTradeCardValidatorTests\" --nologo -v quiet 2>$null)"
     ]
   }
 }
diff --git a/FruitBank.Common.Server/FruitBankConst.cs b/FruitBank.Common.Server/FruitBankConst.cs
index c60e6ca0..ab279d71 100644
--- a/FruitBank.Common.Server/FruitBankConst.cs
+++ b/FruitBank.Common.Server/FruitBankConst.cs
@@ -27,6 +27,30 @@ namespace FruitBank.Common.Server
         /// </summary>
         public const string PreOrderWindowEnd = "PreOrderWindowEnd";
 
+        // ── Environment flag — method-only surface on purpose: no property to bind/serialize/read accidentally ──
+
+        private static bool? _isProd;
+
+        /// <summary>
+        /// Set once by the plugin startup after DB-catalog classification.
+        /// A second call with a different value throws — the flag cannot flip at runtime.
+        /// </summary>
+        public static void SetIsProd(bool isProd)
+        {
+            if (_isProd.HasValue && _isProd.Value != isProd)
+                throw new InvalidOperationException(
+                    $"IsProd is already set to {_isProd.Value}; refusing to change it to {isProd}.");
+
+            _isProd = isProd;
+        }
+
+        /// <summary>
+        /// True = PROD database. Throws until SetIsProd ran — an uninitialized read must never return a default.
+        /// </summary>
+        public static bool IsProd()
+            => _isProd ?? throw new InvalidOperationException(
+                "IsProd has not been initialized — SetIsProd must run at startup before any read.");
+
         static FruitBankConst()
         {
             ProjectId = Guid.Parse(ProjectIdString);
diff --git a/FruitBank.Common.Server/Services/Loggers/LoggerToLoggerApiController.cs b/FruitBank.Common.Server/Services/Loggers/LoggerToLoggerApiController.cs
index 6ba04041..ef89e8ee 100644
--- a/FruitBank.Common.Server/Services/Loggers/LoggerToLoggerApiController.cs
+++ b/FruitBank.Common.Server/Services/Loggers/LoggerToLoggerApiController.cs
@@ -6,6 +6,9 @@ namespace FruitBank.Common.Server.Services.Loggers;
 
 public class LoggerToLoggerApiController : Logger<LoggerToLoggerApiController>
 {
-    public LoggerToLoggerApiController(params IAcLogWriterBase[] logWriters) : base(logWriters)
+    // IEnumerable — a MS DI tömböt ("params IAcLogWriterBase[]") NEM tud feloldani (InvalidOperationException:
+    // Unable to resolve service for type 'IAcLogWriterBase[]'), amitől a LoggerSignalRHub aktiválása minden
+    // kliens-kapcsolódásnál elszállt, és a felküldött kliens-logok némán elvesztek.
+    public LoggerToLoggerApiController(IEnumerable<IAcLogWriterBase> logWriters) : base(logWriters.ToArray())
     { }
 }
\ No newline at end of file
diff --git a/FruitBank.Common/Interfaces/IFruitBankDataControllerCommon.cs b/FruitBank.Common/Interfaces/IFruitBankDataControllerCommon.cs
index 7e1277b4..ffc7e4dc 100644
--- a/FruitBank.Common/Interfaces/IFruitBankDataControllerCommon.cs
+++ b/FruitBank.Common/Interfaces/IFruitBankDataControllerCommon.cs
@@ -111,6 +111,12 @@ public interface IFruitBankDataControllerCommon
     Task<MgLoginModelResponse?> LoginMeasuringUser(MgLoginModelRequest loginModelRequest);
     Task<List<Partner>?> ProcessAndSaveFullShippingJson(string fullShippingJson, int customerId);
 
+    /// <summary>
+    /// True if the server runs against the PROD database. The value is definite by construction
+    /// (an ambiguous DB catalog fails the server startup); consumers must fail closed on any error.
+    /// </summary>
+    public Task<bool> IsProdEnvironment();
+
     public Task<List<GenericAttributeDto>?> GetGenericAttributeDtosByEntityIdAndKeyGroup(int productId, string keyGroup, int storeId);
 
     public Task<GenericAttributeDto?> AddGenericAttributeDto(GenericAttributeDto genericAttributeDto);
diff --git a/FruitBank.Common/SignalRs/SignalRTags.cs b/FruitBank.Common/SignalRs/SignalRTags.cs
index d62c2ec3..791cf2ab 100644
--- a/FruitBank.Common/SignalRs/SignalRTags.cs
+++ b/FruitBank.Common/SignalRs/SignalRTags.cs
@@ -131,6 +131,8 @@ public class SignalRTags : AcSignalRTags
     public const int AuthenticateUser = 195;
     public const int RefreshToken = 200;
 
+    public const int IsProdEnvironment = 210;
+
     #region SendToClient
     public const int SendOrderChanged = 500;
     public const int SendOrderItemChanged = 501;
diff --git a/FruitBankHybrid.Shared/Services/SignalRs/FruitBankSignalRClient.cs b/FruitBankHybrid.Shared/Services/SignalRs/FruitBankSignalRClient.cs
index a441c500..02bea86d 100644
--- a/FruitBankHybrid.Shared/Services/SignalRs/FruitBankSignalRClient.cs
+++ b/FruitBankHybrid.Shared/Services/SignalRs/FruitBankSignalRClient.cs
@@ -58,6 +58,8 @@ namespace FruitBankHybrid.Shared.Services.SignalRs
 
         public Task<List<MeasuringModel>?> GetMeasuringModels() => GetAllAsync<List<MeasuringModel>>(SignalRTags.GetMeasuringModels);
 
+        public Task<bool> IsProdEnvironment() => GetAllAsync<bool>(SignalRTags.IsProdEnvironment);
+
         #region Partner
         public Task<List<Partner>?> GetPartners() => GetAllAsync<List<Partner>>(SignalRTags.GetPartners);
         public Task<Partner?> GetPartnerById(int id) => GetByIdAsync<Partner?>(SignalRTags.GetPartnerById, id);
diff --git a/FruitBankHybrid.Shared/appsettings.json b/FruitBankHybrid.Shared/appsettings.json
index 47f5ae5c..3687fc31 100644
--- a/FruitBankHybrid.Shared/appsettings.json
+++ b/FruitBankHybrid.Shared/appsettings.json
@@ -14,7 +14,7 @@
         //"ApiBaseUrl": "https://shop.fruitbank.hu"
       },
 	    "Logger": {
-		    "AppType": "Server",
+		    "AppType": "Web",
 		    "LogLevel": "Detail",
 		    "LogWriters": [
 			    {
diff --git a/FruitBankHybrid.Web.Client/Program.cs b/FruitBankHybrid.Web.Client/Program.cs
index 83cfc671..1cf2d9ba 100644
--- a/FruitBankHybrid.Web.Client/Program.cs
+++ b/FruitBankHybrid.Web.Client/Program.cs
@@ -1,3 +1,4 @@
+using AyCode.Core.Enums;
 using AyCode.Core.Loggers;
 using AyCode.Core.Serializers.Binaries;
 using AyCode.Services.SignalRs;
@@ -43,9 +44,10 @@ builder.Services.Configure<AcBinaryHubProtocolOptions>(opts =>
 });
 
 // Logger options + framework factory. LoggerClient instances are created per caller category,
-// with AppType+LogLevel from appsettings and writers resolved from DI via IAcLogWriterClientBase.
+// with LogLevel from appsettings and writers resolved from DI via IAcLogWriterClientBase.
+// AppType: a WASM kliens kód-defaultja Web — az appsettings (AyCode:Logger:AppType) felülírhatja, ha megadja.
 builder.Services.Configure<AcLoggerOptions>(builder.Configuration.GetSection("AyCode:Logger"));
-builder.Services.AddAcLoggerFactory<LoggerClient, IAcLogWriterClientBase>();
+builder.Services.AddAcLoggerFactory<LoggerClient, IAcLogWriterClientBase>(AppType.Web);
 
 // HubConnectionBuilder — transient so each consumer gets a fresh builder to Build().
 // All connection and protocol configuration flows from appsettings.json via IOptions<T>;
diff --git a/FruitBankHybrid.Web.Client/wwwroot/appsettings.json b/FruitBankHybrid.Web.Client/wwwroot/appsettings.json
index 47f5ae5c..3687fc31 100644
--- a/FruitBankHybrid.Web.Client/wwwroot/appsettings.json
+++ b/FruitBankHybrid.Web.Client/wwwroot/appsettings.json
@@ -14,7 +14,7 @@
         //"ApiBaseUrl": "https://shop.fruitbank.hu"
       },
 	    "Logger": {
-		    "AppType": "Server",
+		    "AppType": "Web",
 		    "LogLevel": "Detail",
 		    "LogWriters": [
 			    {
diff --git a/FruitBankHybrid.Web/Program.cs b/FruitBankHybrid.Web/Program.cs
index 56965a95..05d85dff 100644
--- a/FruitBankHybrid.Web/Program.cs
+++ b/FruitBankHybrid.Web/Program.cs
@@ -1,3 +1,4 @@
+using AyCode.Core.Enums;
 using AyCode.Core.Loggers;
 using AyCode.Core.Serializers.Binaries;
 using AyCode.Services.SignalRs;
@@ -26,9 +27,10 @@ builder.Services.AddSingleton<ISecureCredentialService, ServerSecureCredentialSe
 builder.Services.AddSingleton<IAcLogWriterBase, ConsoleLogWriter>();
 
 // Logger options + framework factory. LoggerClient instances are created per caller category,
-// with AppType+LogLevel from appsettings and writers resolved from DI via IAcLogWriterBase.
+// with LogLevel from appsettings and writers resolved from DI via IAcLogWriterBase.
+// AppType: a hybrid WEB-host kód-defaultja Web (az [S] a nop-szerveré) — az appsettings felülírhatja, ha megadja.
 builder.Services.Configure<AcLoggerOptions>(builder.Configuration.GetSection("AyCode:Logger"));
-builder.Services.AddAcLoggerFactory<LoggerClient>();
+builder.Services.AddAcLoggerFactory<LoggerClient>(AppType.Web);
 
 builder.Services.AddSingleton<LoggedInModel>(sp => new LoggedInModel(sp.GetRequiredService<ISecureCredentialService>()));
 
diff --git a/FruitBankHybrid.Web/appsettings.json b/FruitBankHybrid.Web/appsettings.json
index 47f5ae5c..3687fc31 100644
--- a/FruitBankHybrid.Web/appsettings.json
+++ b/FruitBankHybrid.Web/appsettings.json
@@ -14,7 +14,7 @@
         //"ApiBaseUrl": "https://shop.fruitbank.hu"
       },
 	    "Logger": {
-		    "AppType": "Server",
+		    "AppType": "Web",
 		    "LogLevel": "Detail",
 		    "LogWriters": [
 			    {
diff --git a/FruitBankHybrid/MauiProgram.cs b/FruitBankHybrid/MauiProgram.cs
index f310f25c..24f7c1f0 100644
--- a/FruitBankHybrid/MauiProgram.cs
+++ b/FruitBankHybrid/MauiProgram.cs
@@ -1,4 +1,5 @@
-using AyCode.Core.Loggers;
+using AyCode.Core.Enums;
+using AyCode.Core.Loggers;
 using AyCode.Services.SignalRs;
 using FruitBank.Common.Loggers;
 using FruitBank.Common.Models;
@@ -51,9 +52,10 @@ namespace FruitBankHybrid
             builder.Services.AddSingleton<IAcLogWriterClientBase, SignaRClientLogItemWriter>();
 
             // Logger options + framework factory. LoggerClient instances are created per caller category,
-            // with AppType+LogLevel from appsettings and writers resolved from DI via IAcLogWriterClientBase.
+            // with LogLevel from appsettings and writers resolved from DI via IAcLogWriterClientBase.
+            // AppType: a MAUI kliens kód-defaultja Web — az appsettings felülírhatja (pl. Mobile-ra), ha megadja.
             builder.Services.Configure<AcLoggerOptions>(builder.Configuration.GetSection("AyCode:Logger"));
-            builder.Services.AddAcLoggerFactory<LoggerClient, IAcLogWriterClientBase>();
+            builder.Services.AddAcLoggerFactory<LoggerClient, IAcLogWriterClientBase>(AppType.Web);
 
             // Bind SignalR options from configuration.
             // Precedence: code default → appsettings.json (this line) → any later Configure<T> action.