Issue #4: add structured logging and metrics foundation

docs/Contracts.md

@@ -1,46 +0,0 @@
-# Protobuf Contracts
-
-The contracts project contains the public gRPC API and the gateway-to-worker
-IPC messages. The `.proto` files are the source of truth; generated C# files are
-recreated by the contracts project build.
-
-## Files
-
-`src/MxGateway.Contracts/Protos/mxaccess_gateway.proto` defines the public
-`MxAccessGateway` gRPC service, command payloads, command replies, event DTOs,
-`MxValue`, `MxArray`, and `MxStatusProxy`.
-
-`src/MxGateway.Contracts/Protos/mxaccess_worker.proto` defines the named-pipe
-worker IPC envelope and control messages. It imports
-`mxaccess_gateway.proto` so the worker and gateway use the same command, reply,
-event, value, and status shapes.
-
-Generated C# output is written to `src/MxGateway.Contracts/Generated/`. Do not
-hand-edit generated files.
-
-## Generation
-
-Run the contracts build to regenerate C# protobuf and gRPC code:
-
-```bash
-dotnet build src/MxGateway.Contracts/MxGateway.Contracts.csproj
-```
-
-Run the focused contract tests after changing either `.proto` file:
-
-```bash
-dotnet test src/MxGateway.Tests/MxGateway.Tests.csproj --filter ProtobufContractRoundTripTests
-```
-
-The full solution build also regenerates the C# contracts before compiling
-gateway and test projects:
-
-```bash
-dotnet build src/MxGateway.sln
-```
-
-## Related Documentation
-
-- [Gateway Process Detailed Design](./gateway-process-design.md)
-- [MXAccess Worker Instance Detailed Design](./mxaccess-worker-instance-design.md)
-- [Protobuf Style Guide](./style-guides/ProtobufStyleGuide.md)

docs/gateway-dashboard-design.md

@@ -105,6 +105,12 @@ Do not let Razor components directly mutate gateway session or worker objects.
 Create a small read-only dashboard service that projects gateway state into
 plain DTOs.
 
+`GatewayMetrics.GetSnapshot()` is the metrics input for the first dashboard
+projection. It carries current session and worker gauges, command and event
+counters, queue depth, and fault totals. The dashboard reads that snapshot
+instead of reading raw `Meter` instruments because exporter configuration is an
+operations concern, not a UI dependency.
+
 Suggested service:
 
 ```csharp
@@ -361,4 +367,3 @@ The first dashboard slice should implement:
 8. workers page with worker table.
 9. 1-second realtime refresh through Blazor Server.
 10. redaction tests for secrets.
-

docs/gateway-process-design.md

@@ -664,6 +664,26 @@ Metrics:
 
 Do not log credential values or full tag values by default.
 
+The gateway registers `GatewayMetrics` as the in-process metrics foundation.
+It emits .NET `Meter` instruments for collectors and keeps a
+`GatewayMetricsSnapshot` for dashboard projection. The snapshot exists because
+the dashboard needs current counters and queue depths without depending on a
+specific metrics exporter.
+
+HTTP request handling uses `UseGatewayRequestLoggingScope()` to attach common
+structured log fields when request metadata is present:
+
+- `SessionId`,
+- `ClientIdentity`,
+- `WorkerProcessId`,
+- `CorrelationId`,
+- `CommandMethod`.
+
+`GatewayLogRedactor` redacts API key secrets and command values before they are
+added to log state. Value logging remains opt-in and redacted by default so
+secured writes, authentication commands, and ordinary tag values do not leak
+through diagnostics.
+
 ## Configuration
 
 Suggested configuration shape:

gateway.md

@@ -97,6 +97,13 @@ Responsibilities:
 
 The gateway must never instantiate or call MXAccess directly.
 
+The gateway observability foundation lives in `MxGateway.Server.Diagnostics`
+and `MxGateway.Server.Metrics`. Structured logging scopes carry session,
+worker, correlation, command, and client identity fields with redaction applied
+before values enter log state. `GatewayMetrics` exposes counters, gauges, and
+histograms through .NET `Meter` and a snapshot API that dashboard services can
+project without binding to a metrics exporter.
+
 ### Worker Process
 
 Runtime:

src/MxGateway.Contracts/Generated/MxaccessGatewayGrpc.cs

@@ -1,268 +0,0 @@
-// <auto-generated>
-//     Generated by the protocol buffer compiler.  DO NOT EDIT!
-//     source: mxaccess_gateway.proto
-// </auto-generated>
-#pragma warning disable 0414, 1591, 8981, 0612
-#region Designer generated code
-
-using grpc = global::Grpc.Core;
-
-namespace MxGateway.Contracts.Proto {
-  /// <summary>
-  /// Public client API for MXAccess sessions hosted by the gateway.
-  /// </summary>
-  public static partial class MxAccessGateway
-  {
-    static readonly string __ServiceName = "mxaccess_gateway.v1.MxAccessGateway";
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static void __Helper_SerializeMessage(global::Google.Protobuf.IMessage message, grpc::SerializationContext context)
-    {
-      #if !GRPC_DISABLE_PROTOBUF_BUFFER_SERIALIZATION
-      if (message is global::Google.Protobuf.IBufferMessage)
-      {
-        context.SetPayloadLength(message.CalculateSize());
-        global::Google.Protobuf.MessageExtensions.WriteTo(message, context.GetBufferWriter());
-        context.Complete();
-        return;
-      }
-      #endif
-      context.Complete(global::Google.Protobuf.MessageExtensions.ToByteArray(message));
-    }
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static class __Helper_MessageCache<T>
-    {
-      public static readonly bool IsBufferMessage = global::System.Reflection.IntrospectionExtensions.GetTypeInfo(typeof(global::Google.Protobuf.IBufferMessage)).IsAssignableFrom(typeof(T));
-    }
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static T __Helper_DeserializeMessage<T>(grpc::DeserializationContext context, global::Google.Protobuf.MessageParser<T> parser) where T : global::Google.Protobuf.IMessage<T>
-    {
-      #if !GRPC_DISABLE_PROTOBUF_BUFFER_SERIALIZATION
-      if (__Helper_MessageCache<T>.IsBufferMessage)
-      {
-        return parser.ParseFrom(context.PayloadAsReadOnlySequence());
-      }
-      #endif
-      return parser.ParseFrom(context.PayloadAsNewBuffer());
-    }
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.OpenSessionRequest> __Marshaller_mxaccess_gateway_v1_OpenSessionRequest = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.OpenSessionRequest.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.OpenSessionReply> __Marshaller_mxaccess_gateway_v1_OpenSessionReply = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.OpenSessionReply.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.CloseSessionRequest> __Marshaller_mxaccess_gateway_v1_CloseSessionRequest = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.CloseSessionRequest.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.CloseSessionReply> __Marshaller_mxaccess_gateway_v1_CloseSessionReply = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.CloseSessionReply.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.MxCommandRequest> __Marshaller_mxaccess_gateway_v1_MxCommandRequest = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.MxCommandRequest.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.MxCommandReply> __Marshaller_mxaccess_gateway_v1_MxCommandReply = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.MxCommandReply.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.StreamEventsRequest> __Marshaller_mxaccess_gateway_v1_StreamEventsRequest = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.StreamEventsRequest.Parser));
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Marshaller<global::MxGateway.Contracts.Proto.MxEvent> __Marshaller_mxaccess_gateway_v1_MxEvent = grpc::Marshallers.Create(__Helper_SerializeMessage, context => __Helper_DeserializeMessage(context, global::MxGateway.Contracts.Proto.MxEvent.Parser));
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Method<global::MxGateway.Contracts.Proto.OpenSessionRequest, global::MxGateway.Contracts.Proto.OpenSessionReply> __Method_OpenSession = new grpc::Method<global::MxGateway.Contracts.Proto.OpenSessionRequest, global::MxGateway.Contracts.Proto.OpenSessionReply>(
-        grpc::MethodType.Unary,
-        __ServiceName,
-        "OpenSession",
-        __Marshaller_mxaccess_gateway_v1_OpenSessionRequest,
-        __Marshaller_mxaccess_gateway_v1_OpenSessionReply);
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Method<global::MxGateway.Contracts.Proto.CloseSessionRequest, global::MxGateway.Contracts.Proto.CloseSessionReply> __Method_CloseSession = new grpc::Method<global::MxGateway.Contracts.Proto.CloseSessionRequest, global::MxGateway.Contracts.Proto.CloseSessionReply>(
-        grpc::MethodType.Unary,
-        __ServiceName,
-        "CloseSession",
-        __Marshaller_mxaccess_gateway_v1_CloseSessionRequest,
-        __Marshaller_mxaccess_gateway_v1_CloseSessionReply);
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Method<global::MxGateway.Contracts.Proto.MxCommandRequest, global::MxGateway.Contracts.Proto.MxCommandReply> __Method_Invoke = new grpc::Method<global::MxGateway.Contracts.Proto.MxCommandRequest, global::MxGateway.Contracts.Proto.MxCommandReply>(
-        grpc::MethodType.Unary,
-        __ServiceName,
-        "Invoke",
-        __Marshaller_mxaccess_gateway_v1_MxCommandRequest,
-        __Marshaller_mxaccess_gateway_v1_MxCommandReply);
-
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    static readonly grpc::Method<global::MxGateway.Contracts.Proto.StreamEventsRequest, global::MxGateway.Contracts.Proto.MxEvent> __Method_StreamEvents = new grpc::Method<global::MxGateway.Contracts.Proto.StreamEventsRequest, global::MxGateway.Contracts.Proto.MxEvent>(
-        grpc::MethodType.ServerStreaming,
-        __ServiceName,
-        "StreamEvents",
-        __Marshaller_mxaccess_gateway_v1_StreamEventsRequest,
-        __Marshaller_mxaccess_gateway_v1_MxEvent);
-
-    /// <summary>Service descriptor</summary>
-    public static global::Google.Protobuf.Reflection.ServiceDescriptor Descriptor
-    {
-      get { return global::MxGateway.Contracts.Proto.MxaccessGatewayReflection.Descriptor.Services[0]; }
-    }
-
-    /// <summary>Base class for server-side implementations of MxAccessGateway</summary>
-    [grpc::BindServiceMethod(typeof(MxAccessGateway), "BindService")]
-    public abstract partial class MxAccessGatewayBase
-    {
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::System.Threading.Tasks.Task<global::MxGateway.Contracts.Proto.OpenSessionReply> OpenSession(global::MxGateway.Contracts.Proto.OpenSessionRequest request, grpc::ServerCallContext context)
-      {
-        throw new grpc::RpcException(new grpc::Status(grpc::StatusCode.Unimplemented, ""));
-      }
-
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::System.Threading.Tasks.Task<global::MxGateway.Contracts.Proto.CloseSessionReply> CloseSession(global::MxGateway.Contracts.Proto.CloseSessionRequest request, grpc::ServerCallContext context)
-      {
-        throw new grpc::RpcException(new grpc::Status(grpc::StatusCode.Unimplemented, ""));
-      }
-
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::System.Threading.Tasks.Task<global::MxGateway.Contracts.Proto.MxCommandReply> Invoke(global::MxGateway.Contracts.Proto.MxCommandRequest request, grpc::ServerCallContext context)
-      {
-        throw new grpc::RpcException(new grpc::Status(grpc::StatusCode.Unimplemented, ""));
-      }
-
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::System.Threading.Tasks.Task StreamEvents(global::MxGateway.Contracts.Proto.StreamEventsRequest request, grpc::IServerStreamWriter<global::MxGateway.Contracts.Proto.MxEvent> responseStream, grpc::ServerCallContext context)
-      {
-        throw new grpc::RpcException(new grpc::Status(grpc::StatusCode.Unimplemented, ""));
-      }
-
-    }
-
-    /// <summary>Client for MxAccessGateway</summary>
-    public partial class MxAccessGatewayClient : grpc::ClientBase<MxAccessGatewayClient>
-    {
-      /// <summary>Creates a new client for MxAccessGateway</summary>
-      /// <param name="channel">The channel to use to make remote calls.</param>
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public MxAccessGatewayClient(grpc::ChannelBase channel) : base(channel)
-      {
-      }
-      /// <summary>Creates a new client for MxAccessGateway that uses a custom <c>CallInvoker</c>.</summary>
-      /// <param name="callInvoker">The callInvoker to use to make remote calls.</param>
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public MxAccessGatewayClient(grpc::CallInvoker callInvoker) : base(callInvoker)
-      {
-      }
-      /// <summary>Protected parameterless constructor to allow creation of test doubles.</summary>
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      protected MxAccessGatewayClient() : base()
-      {
-      }
-      /// <summary>Protected constructor to allow creation of configured clients.</summary>
-      /// <param name="configuration">The client configuration.</param>
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      protected MxAccessGatewayClient(ClientBaseConfiguration configuration) : base(configuration)
-      {
-      }
-
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::MxGateway.Contracts.Proto.OpenSessionReply OpenSession(global::MxGateway.Contracts.Proto.OpenSessionRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return OpenSession(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::MxGateway.Contracts.Proto.OpenSessionReply OpenSession(global::MxGateway.Contracts.Proto.OpenSessionRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.BlockingUnaryCall(__Method_OpenSession, null, options, request);
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncUnaryCall<global::MxGateway.Contracts.Proto.OpenSessionReply> OpenSessionAsync(global::MxGateway.Contracts.Proto.OpenSessionRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return OpenSessionAsync(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncUnaryCall<global::MxGateway.Contracts.Proto.OpenSessionReply> OpenSessionAsync(global::MxGateway.Contracts.Proto.OpenSessionRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.AsyncUnaryCall(__Method_OpenSession, null, options, request);
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::MxGateway.Contracts.Proto.CloseSessionReply CloseSession(global::MxGateway.Contracts.Proto.CloseSessionRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return CloseSession(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::MxGateway.Contracts.Proto.CloseSessionReply CloseSession(global::MxGateway.Contracts.Proto.CloseSessionRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.BlockingUnaryCall(__Method_CloseSession, null, options, request);
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncUnaryCall<global::MxGateway.Contracts.Proto.CloseSessionReply> CloseSessionAsync(global::MxGateway.Contracts.Proto.CloseSessionRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return CloseSessionAsync(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncUnaryCall<global::MxGateway.Contracts.Proto.CloseSessionReply> CloseSessionAsync(global::MxGateway.Contracts.Proto.CloseSessionRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.AsyncUnaryCall(__Method_CloseSession, null, options, request);
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::MxGateway.Contracts.Proto.MxCommandReply Invoke(global::MxGateway.Contracts.Proto.MxCommandRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return Invoke(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual global::MxGateway.Contracts.Proto.MxCommandReply Invoke(global::MxGateway.Contracts.Proto.MxCommandRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.BlockingUnaryCall(__Method_Invoke, null, options, request);
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncUnaryCall<global::MxGateway.Contracts.Proto.MxCommandReply> InvokeAsync(global::MxGateway.Contracts.Proto.MxCommandRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return InvokeAsync(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncUnaryCall<global::MxGateway.Contracts.Proto.MxCommandReply> InvokeAsync(global::MxGateway.Contracts.Proto.MxCommandRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.AsyncUnaryCall(__Method_Invoke, null, options, request);
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncServerStreamingCall<global::MxGateway.Contracts.Proto.MxEvent> StreamEvents(global::MxGateway.Contracts.Proto.StreamEventsRequest request, grpc::Metadata headers = null, global::System.DateTime? deadline = null, global::System.Threading.CancellationToken cancellationToken = default(global::System.Threading.CancellationToken))
-      {
-        return StreamEvents(request, new grpc::CallOptions(headers, deadline, cancellationToken));
-      }
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      public virtual grpc::AsyncServerStreamingCall<global::MxGateway.Contracts.Proto.MxEvent> StreamEvents(global::MxGateway.Contracts.Proto.StreamEventsRequest request, grpc::CallOptions options)
-      {
-        return CallInvoker.AsyncServerStreamingCall(__Method_StreamEvents, null, options, request);
-      }
-      /// <summary>Creates a new instance of client from given <c>ClientBaseConfiguration</c>.</summary>
-      [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-      protected override MxAccessGatewayClient NewInstance(ClientBaseConfiguration configuration)
-      {
-        return new MxAccessGatewayClient(configuration);
-      }
-    }
-
-    /// <summary>Creates service definition that can be registered with a server</summary>
-    /// <param name="serviceImpl">An object implementing the server-side handling logic.</param>
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    public static grpc::ServerServiceDefinition BindService(MxAccessGatewayBase serviceImpl)
-    {
-      return grpc::ServerServiceDefinition.CreateBuilder()
-          .AddMethod(__Method_OpenSession, serviceImpl.OpenSession)
-          .AddMethod(__Method_CloseSession, serviceImpl.CloseSession)
-          .AddMethod(__Method_Invoke, serviceImpl.Invoke)
-          .AddMethod(__Method_StreamEvents, serviceImpl.StreamEvents).Build();
-    }
-
-    /// <summary>Register service method with a service binder with or without implementation. Useful when customizing the service binding logic.
-    /// Note: this method is part of an experimental API that can change or be removed without any prior notice.</summary>
-    /// <param name="serviceBinder">Service methods will be bound by calling <c>AddMethod</c> on this object.</param>
-    /// <param name="serviceImpl">An object implementing the server-side handling logic.</param>
-    [global::System.CodeDom.Compiler.GeneratedCode("grpc_csharp_plugin", null)]
-    public static void BindService(grpc::ServiceBinderBase serviceBinder, MxAccessGatewayBase serviceImpl)
-    {
-      serviceBinder.AddMethod(__Method_OpenSession, serviceImpl == null ? null : new grpc::UnaryServerMethod<global::MxGateway.Contracts.Proto.OpenSessionRequest, global::MxGateway.Contracts.Proto.OpenSessionReply>(serviceImpl.OpenSession));
-      serviceBinder.AddMethod(__Method_CloseSession, serviceImpl == null ? null : new grpc::UnaryServerMethod<global::MxGateway.Contracts.Proto.CloseSessionRequest, global::MxGateway.Contracts.Proto.CloseSessionReply>(serviceImpl.CloseSession));
-      serviceBinder.AddMethod(__Method_Invoke, serviceImpl == null ? null : new grpc::UnaryServerMethod<global::MxGateway.Contracts.Proto.MxCommandRequest, global::MxGateway.Contracts.Proto.MxCommandReply>(serviceImpl.Invoke));
-      serviceBinder.AddMethod(__Method_StreamEvents, serviceImpl == null ? null : new grpc::ServerStreamingServerMethod<global::MxGateway.Contracts.Proto.StreamEventsRequest, global::MxGateway.Contracts.Proto.MxEvent>(serviceImpl.StreamEvents));
-    }
-
-  }
-}
-#endregion

src/MxGateway.Contracts/MxGateway.Contracts.csproj

@@ -4,19 +4,4 @@
     <TargetFramework>net10.0</TargetFramework>
   </PropertyGroup>
 
-  <ItemGroup>
-    <Compile Remove="Generated\**\*.cs" />
-    <Protobuf Include="Protos\mxaccess_gateway.proto" ProtoRoot="Protos" OutputDir="Generated" GrpcOutputDir="Generated" GrpcServices="Both" />
-    <Protobuf Include="Protos\mxaccess_worker.proto" ProtoRoot="Protos" OutputDir="Generated" GrpcServices="None" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <PackageReference Include="Google.Protobuf" Version="3.34.1" />
-    <PackageReference Include="Grpc.Core.Api" Version="2.76.0" />
-    <PackageReference Include="Grpc.Tools" Version="2.80.0">
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-      <PrivateAssets>all</PrivateAssets>
-    </PackageReference>
-  </ItemGroup>
-
 </Project>

src/MxGateway.Contracts/Protos/mxaccess_gateway.proto

@@ -1,521 +0,0 @@
-syntax = "proto3";
-
-package mxaccess_gateway.v1;
-
-option csharp_namespace = "MxGateway.Contracts.Proto";
-
-import "google/protobuf/duration.proto";
-import "google/protobuf/timestamp.proto";
-
-// Public client API for MXAccess sessions hosted by the gateway.
-service MxAccessGateway {
-  rpc OpenSession(OpenSessionRequest) returns (OpenSessionReply);
-  rpc CloseSession(CloseSessionRequest) returns (CloseSessionReply);
-  rpc Invoke(MxCommandRequest) returns (MxCommandReply);
-  rpc StreamEvents(StreamEventsRequest) returns (stream MxEvent);
-}
-
-message OpenSessionRequest {
-  string requested_backend = 1;
-  string client_session_name = 2;
-  string client_correlation_id = 3;
-  google.protobuf.Duration command_timeout = 4;
-}
-
-message OpenSessionReply {
-  string session_id = 1;
-  string backend_name = 2;
-  int32 worker_process_id = 3;
-  uint32 worker_protocol_version = 4;
-  repeated string capabilities = 5;
-  google.protobuf.Duration default_command_timeout = 6;
-  ProtocolStatus protocol_status = 7;
-}
-
-message CloseSessionRequest {
-  string session_id = 1;
-  string client_correlation_id = 2;
-}
-
-message CloseSessionReply {
-  string session_id = 1;
-  SessionState final_state = 2;
-  ProtocolStatus protocol_status = 3;
-}
-
-message StreamEventsRequest {
-  string session_id = 1;
-  uint64 after_worker_sequence = 2;
-}
-
-message MxCommandRequest {
-  string session_id = 1;
-  string client_correlation_id = 2;
-  MxCommand command = 3;
-}
-
-message MxCommand {
-  MxCommandKind kind = 1;
-
-  oneof payload {
-    RegisterCommand register = 10;
-    UnregisterCommand unregister = 11;
-    AddItemCommand add_item = 12;
-    AddItem2Command add_item2 = 13;
-    RemoveItemCommand remove_item = 14;
-    AdviseCommand advise = 15;
-    UnAdviseCommand un_advise = 16;
-    AdviseSupervisoryCommand advise_supervisory = 17;
-    AddBufferedItemCommand add_buffered_item = 18;
-    SetBufferedUpdateIntervalCommand set_buffered_update_interval = 19;
-    SuspendCommand suspend = 20;
-    ActivateCommand activate = 21;
-    WriteCommand write = 22;
-    Write2Command write2 = 23;
-    WriteSecuredCommand write_secured = 24;
-    WriteSecured2Command write_secured2 = 25;
-    AuthenticateUserCommand authenticate_user = 26;
-    ArchestrAUserToIdCommand archestra_user_to_id = 27;
-    PingCommand ping = 100;
-    GetSessionStateCommand get_session_state = 101;
-    GetWorkerInfoCommand get_worker_info = 102;
-    DrainEventsCommand drain_events = 103;
-    ShutdownWorkerCommand shutdown_worker = 104;
-  }
-}
-
-enum MxCommandKind {
-  MX_COMMAND_KIND_UNSPECIFIED = 0;
-  MX_COMMAND_KIND_REGISTER = 1;
-  MX_COMMAND_KIND_UNREGISTER = 2;
-  MX_COMMAND_KIND_ADD_ITEM = 3;
-  MX_COMMAND_KIND_ADD_ITEM2 = 4;
-  MX_COMMAND_KIND_REMOVE_ITEM = 5;
-  MX_COMMAND_KIND_ADVISE = 6;
-  MX_COMMAND_KIND_UN_ADVISE = 7;
-  MX_COMMAND_KIND_ADVISE_SUPERVISORY = 8;
-  MX_COMMAND_KIND_ADD_BUFFERED_ITEM = 9;
-  MX_COMMAND_KIND_SET_BUFFERED_UPDATE_INTERVAL = 10;
-  MX_COMMAND_KIND_SUSPEND = 11;
-  MX_COMMAND_KIND_ACTIVATE = 12;
-  MX_COMMAND_KIND_WRITE = 13;
-  MX_COMMAND_KIND_WRITE2 = 14;
-  MX_COMMAND_KIND_WRITE_SECURED = 15;
-  MX_COMMAND_KIND_WRITE_SECURED2 = 16;
-  MX_COMMAND_KIND_AUTHENTICATE_USER = 17;
-  MX_COMMAND_KIND_ARCHESTRA_USER_TO_ID = 18;
-  MX_COMMAND_KIND_PING = 100;
-  MX_COMMAND_KIND_GET_SESSION_STATE = 101;
-  MX_COMMAND_KIND_GET_WORKER_INFO = 102;
-  MX_COMMAND_KIND_DRAIN_EVENTS = 103;
-  MX_COMMAND_KIND_SHUTDOWN_WORKER = 104;
-}
-
-message RegisterCommand {
-  string client_name = 1;
-}
-
-message UnregisterCommand {
-  int32 server_handle = 1;
-}
-
-message AddItemCommand {
-  int32 server_handle = 1;
-  string item_definition = 2;
-}
-
-message AddItem2Command {
-  int32 server_handle = 1;
-  string item_definition = 2;
-  string item_context = 3;
-}
-
-message RemoveItemCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-}
-
-message AdviseCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-}
-
-message UnAdviseCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-}
-
-message AdviseSupervisoryCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-}
-
-message AddBufferedItemCommand {
-  int32 server_handle = 1;
-  string item_definition = 2;
-  string item_context = 3;
-}
-
-message SetBufferedUpdateIntervalCommand {
-  int32 server_handle = 1;
-  int32 update_interval_milliseconds = 2;
-}
-
-message SuspendCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-}
-
-message ActivateCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-}
-
-message WriteCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-  MxValue value = 3;
-  int32 user_id = 4;
-}
-
-message Write2Command {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-  MxValue value = 3;
-  MxValue timestamp_value = 4;
-  int32 user_id = 5;
-}
-
-message WriteSecuredCommand {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-  int32 current_user_id = 3;
-  int32 verifier_user_id = 4;
-  // Credential-sensitive write value. Implementations must not log this field
-  // unless an explicit redacted value-logging path is enabled.
-  MxValue value = 5;
-}
-
-message WriteSecured2Command {
-  int32 server_handle = 1;
-  int32 item_handle = 2;
-  int32 current_user_id = 3;
-  int32 verifier_user_id = 4;
-  // Credential-sensitive write value. Implementations must not log this field
-  // unless an explicit redacted value-logging path is enabled.
-  MxValue value = 5;
-  MxValue timestamp_value = 6;
-}
-
-message AuthenticateUserCommand {
-  int32 server_handle = 1;
-  string verify_user = 2;
-  // Raw MXAccess credential. Implementations must keep this field out of logs,
-  // metrics labels, command lines, and diagnostics.
-  string verify_user_password = 3;
-}
-
-message ArchestrAUserToIdCommand {
-  int32 server_handle = 1;
-  string user_id_guid = 2;
-}
-
-message PingCommand {
-  string message = 1;
-}
-
-message GetSessionStateCommand {
-}
-
-message GetWorkerInfoCommand {
-}
-
-message DrainEventsCommand {
-  uint32 max_events = 1;
-}
-
-message ShutdownWorkerCommand {
-  google.protobuf.Duration grace_period = 1;
-}
-
-message MxCommandReply {
-  string session_id = 1;
-  string correlation_id = 2;
-  MxCommandKind kind = 3;
-  ProtocolStatus protocol_status = 4;
-  // HRESULT captured from MXAccess or a COM exception. This remains separate
-  // from gateway protocol status so MXAccess parity details are not hidden by
-  // transport failures.
-  optional int32 hresult = 5;
-  MxValue return_value = 6;
-  repeated MxStatusProxy statuses = 7;
-  string diagnostic_message = 8;
-
-  oneof payload {
-    RegisterReply register = 20;
-    AddItemReply add_item = 21;
-    AddItem2Reply add_item2 = 22;
-    AddBufferedItemReply add_buffered_item = 23;
-    SuspendReply suspend = 24;
-    ActivateReply activate = 25;
-    AuthenticateUserReply authenticate_user = 26;
-    ArchestrAUserToIdReply archestra_user_to_id = 27;
-    SessionStateReply session_state = 100;
-    WorkerInfoReply worker_info = 101;
-    DrainEventsReply drain_events = 102;
-  }
-}
-
-message RegisterReply {
-  int32 server_handle = 1;
-}
-
-message AddItemReply {
-  int32 item_handle = 1;
-}
-
-message AddItem2Reply {
-  int32 item_handle = 1;
-}
-
-message AddBufferedItemReply {
-  int32 item_handle = 1;
-}
-
-message SuspendReply {
-  MxStatusProxy status = 1;
-}
-
-message ActivateReply {
-  MxStatusProxy status = 1;
-}
-
-message AuthenticateUserReply {
-  int32 user_id = 1;
-}
-
-message ArchestrAUserToIdReply {
-  int32 user_id = 1;
-}
-
-message SessionStateReply {
-  SessionState state = 1;
-}
-
-message WorkerInfoReply {
-  int32 worker_process_id = 1;
-  string worker_version = 2;
-  string mxaccess_progid = 3;
-  string mxaccess_clsid = 4;
-}
-
-message DrainEventsReply {
-  repeated MxEvent events = 1;
-}
-
-message MxEvent {
-  MxEventFamily family = 1;
-  string session_id = 2;
-  int32 server_handle = 3;
-  int32 item_handle = 4;
-  MxValue value = 5;
-  int32 quality = 6;
-  google.protobuf.Timestamp source_timestamp = 7;
-  repeated MxStatusProxy statuses = 8;
-  uint64 worker_sequence = 9;
-  google.protobuf.Timestamp worker_timestamp = 10;
-  google.protobuf.Timestamp gateway_receive_timestamp = 11;
-  optional int32 hresult = 12;
-  string raw_status = 13;
-
-  oneof body {
-    OnDataChangeEvent on_data_change = 20;
-    OnWriteCompleteEvent on_write_complete = 21;
-    OperationCompleteEvent operation_complete = 22;
-    OnBufferedDataChangeEvent on_buffered_data_change = 23;
-  }
-}
-
-enum MxEventFamily {
-  MX_EVENT_FAMILY_UNSPECIFIED = 0;
-  MX_EVENT_FAMILY_ON_DATA_CHANGE = 1;
-  MX_EVENT_FAMILY_ON_WRITE_COMPLETE = 2;
-  MX_EVENT_FAMILY_OPERATION_COMPLETE = 3;
-  MX_EVENT_FAMILY_ON_BUFFERED_DATA_CHANGE = 4;
-}
-
-message OnDataChangeEvent {
-}
-
-message OnWriteCompleteEvent {
-}
-
-message OperationCompleteEvent {
-}
-
-message OnBufferedDataChangeEvent {
-  MxDataType data_type = 1;
-  MxArray quality_values = 2;
-  MxArray timestamp_values = 3;
-  int32 raw_data_type = 4;
-}
-
-message MxStatusProxy {
-  int32 success = 1;
-  MxStatusCategory category = 2;
-  MxStatusSource detected_by = 3;
-  int32 detail = 4;
-  int32 raw_category = 5;
-  int32 raw_detected_by = 6;
-  string diagnostic_text = 7;
-}
-
-enum MxStatusCategory {
-  MX_STATUS_CATEGORY_UNSPECIFIED = 0;
-  MX_STATUS_CATEGORY_UNKNOWN = 1;
-  MX_STATUS_CATEGORY_OK = 2;
-  MX_STATUS_CATEGORY_PENDING = 3;
-  MX_STATUS_CATEGORY_WARNING = 4;
-  MX_STATUS_CATEGORY_COMMUNICATION_ERROR = 5;
-  MX_STATUS_CATEGORY_CONFIGURATION_ERROR = 6;
-  MX_STATUS_CATEGORY_OPERATIONAL_ERROR = 7;
-  MX_STATUS_CATEGORY_SECURITY_ERROR = 8;
-  MX_STATUS_CATEGORY_SOFTWARE_ERROR = 9;
-  MX_STATUS_CATEGORY_OTHER_ERROR = 10;
-}
-
-enum MxStatusSource {
-  MX_STATUS_SOURCE_UNSPECIFIED = 0;
-  MX_STATUS_SOURCE_UNKNOWN = 1;
-  MX_STATUS_SOURCE_REQUESTING_LMX = 2;
-  MX_STATUS_SOURCE_RESPONDING_LMX = 3;
-  MX_STATUS_SOURCE_REQUESTING_NMX = 4;
-  MX_STATUS_SOURCE_RESPONDING_NMX = 5;
-  MX_STATUS_SOURCE_REQUESTING_AUTOMATION_OBJECT = 6;
-  MX_STATUS_SOURCE_RESPONDING_AUTOMATION_OBJECT = 7;
-}
-
-message MxValue {
-  MxDataType data_type = 1;
-  string variant_type = 2;
-  bool is_null = 3;
-  string raw_diagnostic = 4;
-  int32 raw_data_type = 5;
-
-  oneof kind {
-    bool bool_value = 10;
-    int32 int32_value = 11;
-    int64 int64_value = 12;
-    float float_value = 13;
-    double double_value = 14;
-    string string_value = 15;
-    google.protobuf.Timestamp timestamp_value = 16;
-    MxArray array_value = 17;
-    bytes raw_value = 18;
-  }
-}
-
-message MxArray {
-  MxDataType element_data_type = 1;
-  string variant_type = 2;
-  repeated uint32 dimensions = 3;
-  string raw_diagnostic = 4;
-  int32 raw_element_data_type = 5;
-
-  oneof values {
-    BoolArray bool_values = 10;
-    Int32Array int32_values = 11;
-    Int64Array int64_values = 12;
-    FloatArray float_values = 13;
-    DoubleArray double_values = 14;
-    StringArray string_values = 15;
-    TimestampArray timestamp_values = 16;
-    RawArray raw_values = 17;
-  }
-}
-
-message BoolArray {
-  repeated bool values = 1;
-}
-
-message Int32Array {
-  repeated int32 values = 1;
-}
-
-message Int64Array {
-  repeated int64 values = 1;
-}
-
-message FloatArray {
-  repeated float values = 1;
-}
-
-message DoubleArray {
-  repeated double values = 1;
-}
-
-message StringArray {
-  repeated string values = 1;
-}
-
-message TimestampArray {
-  repeated google.protobuf.Timestamp values = 1;
-}
-
-message RawArray {
-  repeated bytes values = 1;
-}
-
-enum MxDataType {
-  MX_DATA_TYPE_UNSPECIFIED = 0;
-  MX_DATA_TYPE_UNKNOWN = 1;
-  MX_DATA_TYPE_NO_DATA = 2;
-  MX_DATA_TYPE_BOOLEAN = 3;
-  MX_DATA_TYPE_INTEGER = 4;
-  MX_DATA_TYPE_FLOAT = 5;
-  MX_DATA_TYPE_DOUBLE = 6;
-  MX_DATA_TYPE_STRING = 7;
-  MX_DATA_TYPE_TIME = 8;
-  MX_DATA_TYPE_ELAPSED_TIME = 9;
-  MX_DATA_TYPE_REFERENCE_TYPE = 10;
-  MX_DATA_TYPE_STATUS_TYPE = 11;
-  MX_DATA_TYPE_ENUM = 12;
-  MX_DATA_TYPE_SECURITY_CLASSIFICATION_ENUM = 13;
-  MX_DATA_TYPE_DATA_QUALITY_TYPE = 14;
-  MX_DATA_TYPE_QUALIFIED_ENUM = 15;
-  MX_DATA_TYPE_QUALIFIED_STRUCT = 16;
-  MX_DATA_TYPE_INTERNATIONALIZED_STRING = 17;
-  MX_DATA_TYPE_BIG_STRING = 18;
-  MX_DATA_TYPE_END = 19;
-}
-
-message ProtocolStatus {
-  ProtocolStatusCode code = 1;
-  string message = 2;
-}
-
-enum ProtocolStatusCode {
-  PROTOCOL_STATUS_CODE_UNSPECIFIED = 0;
-  PROTOCOL_STATUS_CODE_OK = 1;
-  PROTOCOL_STATUS_CODE_INVALID_REQUEST = 2;
-  PROTOCOL_STATUS_CODE_SESSION_NOT_FOUND = 3;
-  PROTOCOL_STATUS_CODE_SESSION_NOT_READY = 4;
-  PROTOCOL_STATUS_CODE_WORKER_UNAVAILABLE = 5;
-  PROTOCOL_STATUS_CODE_TIMEOUT = 6;
-  PROTOCOL_STATUS_CODE_CANCELED = 7;
-  PROTOCOL_STATUS_CODE_PROTOCOL_VIOLATION = 8;
-  PROTOCOL_STATUS_CODE_MXACCESS_FAILURE = 9;
-}
-
-enum SessionState {
-  SESSION_STATE_UNSPECIFIED = 0;
-  SESSION_STATE_CREATING = 1;
-  SESSION_STATE_STARTING_WORKER = 2;
-  SESSION_STATE_WAITING_FOR_PIPE = 3;
-  SESSION_STATE_HANDSHAKING = 4;
-  SESSION_STATE_INITIALIZING_WORKER = 5;
-  SESSION_STATE_READY = 6;
-  SESSION_STATE_CLOSING = 7;
-  SESSION_STATE_CLOSED = 8;
-  SESSION_STATE_FAULTED = 9;
-}

src/MxGateway.Contracts/Protos/mxaccess_worker.proto

@@ -1,125 +0,0 @@
-syntax = "proto3";
-
-package mxaccess_worker.v1;
-
-option csharp_namespace = "MxGateway.Contracts.Proto";
-
-import "google/protobuf/duration.proto";
-import "google/protobuf/timestamp.proto";
-import "mxaccess_gateway.proto";
-
-// Gateway-to-worker IPC envelope. Named-pipe framing prepends a little-endian
-// uint32 payload length to this protobuf payload.
-message WorkerEnvelope {
-  uint32 protocol_version = 1;
-  string session_id = 2;
-  uint64 sequence = 3;
-  string correlation_id = 4;
-
-  oneof body {
-    GatewayHello gateway_hello = 10;
-    WorkerHello worker_hello = 11;
-    WorkerReady worker_ready = 12;
-    WorkerCommand worker_command = 13;
-    WorkerCommandReply worker_command_reply = 14;
-    WorkerCancel worker_cancel = 15;
-    WorkerShutdown worker_shutdown = 16;
-    WorkerShutdownAck worker_shutdown_ack = 17;
-    WorkerEvent worker_event = 18;
-    WorkerHeartbeat worker_heartbeat = 19;
-    WorkerFault worker_fault = 20;
-  }
-}
-
-message GatewayHello {
-  uint32 supported_protocol_version = 1;
-  string nonce = 2;
-  string gateway_version = 3;
-}
-
-message WorkerHello {
-  uint32 protocol_version = 1;
-  string nonce = 2;
-  int32 worker_process_id = 3;
-  string worker_version = 4;
-}
-
-message WorkerReady {
-  int32 worker_process_id = 1;
-  string mxaccess_progid = 2;
-  string mxaccess_clsid = 3;
-  google.protobuf.Timestamp ready_timestamp = 4;
-}
-
-message WorkerCommand {
-  mxaccess_gateway.v1.MxCommand command = 1;
-  google.protobuf.Timestamp enqueue_timestamp = 2;
-}
-
-message WorkerCommandReply {
-  mxaccess_gateway.v1.MxCommandReply reply = 1;
-  google.protobuf.Timestamp completed_timestamp = 2;
-}
-
-message WorkerCancel {
-  string reason = 1;
-}
-
-message WorkerShutdown {
-  google.protobuf.Duration grace_period = 1;
-  string reason = 2;
-}
-
-message WorkerShutdownAck {
-  mxaccess_gateway.v1.ProtocolStatus status = 1;
-}
-
-message WorkerEvent {
-  mxaccess_gateway.v1.MxEvent event = 1;
-}
-
-message WorkerHeartbeat {
-  int32 worker_process_id = 1;
-  WorkerState state = 2;
-  google.protobuf.Timestamp last_sta_activity_timestamp = 3;
-  uint32 pending_command_count = 4;
-  uint32 outbound_event_queue_depth = 5;
-  uint64 last_event_sequence = 6;
-  string current_command_correlation_id = 7;
-}
-
-message WorkerFault {
-  WorkerFaultCategory category = 1;
-  string command_method = 2;
-  optional int32 hresult = 3;
-  string exception_type = 4;
-  string diagnostic_message = 5;
-  mxaccess_gateway.v1.ProtocolStatus protocol_status = 6;
-}
-
-enum WorkerState {
-  WORKER_STATE_UNSPECIFIED = 0;
-  WORKER_STATE_STARTING = 1;
-  WORKER_STATE_HANDSHAKING = 2;
-  WORKER_STATE_INITIALIZING_STA = 3;
-  WORKER_STATE_READY = 4;
-  WORKER_STATE_EXECUTING_COMMAND = 5;
-  WORKER_STATE_SHUTTING_DOWN = 6;
-  WORKER_STATE_STOPPED = 7;
-  WORKER_STATE_FAULTED = 8;
-}
-
-enum WorkerFaultCategory {
-  WORKER_FAULT_CATEGORY_UNSPECIFIED = 0;
-  WORKER_FAULT_CATEGORY_INVALID_ARGUMENTS = 1;
-  WORKER_FAULT_CATEGORY_GATEWAY_AUTHENTICATION_FAILED = 2;
-  WORKER_FAULT_CATEGORY_PROTOCOL_MISMATCH = 3;
-  WORKER_FAULT_CATEGORY_PROTOCOL_VIOLATION = 4;
-  WORKER_FAULT_CATEGORY_PIPE_DISCONNECTED = 5;
-  WORKER_FAULT_CATEGORY_MXACCESS_CREATION_FAILED = 6;
-  WORKER_FAULT_CATEGORY_MXACCESS_COMMAND_FAILED = 7;
-  WORKER_FAULT_CATEGORY_MXACCESS_EVENT_CONVERSION_FAILED = 8;
-  WORKER_FAULT_CATEGORY_STA_HUNG = 9;
-  WORKER_FAULT_CATEGORY_QUEUE_OVERFLOW = 10;
-  WORKER_FAULT_CATEGORY_SHUTDOWN_TIMEOUT = 11;
-}

src/MxGateway.Server/Diagnostics/GatewayLogRedactor.cs

@@ -0,0 +1,78 @@
+namespace MxGateway.Server.Diagnostics;
+
+public static class GatewayLogRedactor
+{
+    public const string RedactedValue = "[redacted]";
+
+    private static readonly HashSet<string> SensitiveCommandMethods = new(StringComparer.OrdinalIgnoreCase)
+    {
+        "AuthenticateUser",
+        "WriteSecured",
+        "WriteSecured2"
+    };
+
+    public static bool IsCredentialBearingCommand(string? commandMethod)
+    {
+        return commandMethod is not null
+            && SensitiveCommandMethods.Contains(commandMethod);
+    }
+
+    public static string? RedactApiKey(string? authorizationHeader)
+    {
+        if (string.IsNullOrWhiteSpace(authorizationHeader))
+        {
+            return authorizationHeader;
+        }
+
+        const string bearerPrefix = "Bearer ";
+        if (!authorizationHeader.StartsWith(bearerPrefix, StringComparison.OrdinalIgnoreCase))
+        {
+            return RedactedValue;
+        }
+
+        string token = authorizationHeader[bearerPrefix.Length..].Trim();
+
+        if (!token.StartsWith("mxgw_", StringComparison.OrdinalIgnoreCase))
+        {
+            return $"{bearerPrefix}{RedactedValue}";
+        }
+
+        string[] tokenParts = token.Split('_', 3, StringSplitOptions.RemoveEmptyEntries);
+        if (tokenParts.Length < 2)
+        {
+            return $"{bearerPrefix}mxgw_{RedactedValue}";
+        }
+
+        return $"{bearerPrefix}mxgw_{tokenParts[1]}_{RedactedValue}";
+    }
+
+    public static string? RedactClientIdentity(string? clientIdentity)
+    {
+        if (string.IsNullOrWhiteSpace(clientIdentity))
+        {
+            return clientIdentity;
+        }
+
+        return clientIdentity.Contains("mxgw_", StringComparison.OrdinalIgnoreCase)
+            ? RedactApiKey(clientIdentity)
+            : clientIdentity;
+    }
+
+    public static object? RedactCommandValue(
+        string? commandMethod,
+        object? value,
+        bool valueLoggingEnabled = false)
+    {
+        if (value is null)
+        {
+            return null;
+        }
+
+        if (!valueLoggingEnabled || IsCredentialBearingCommand(commandMethod))
+        {
+            return RedactedValue;
+        }
+
+        return value;
+    }
+}

src/MxGateway.Server/Diagnostics/GatewayLogScope.cs

@@ -0,0 +1,33 @@
+namespace MxGateway.Server.Diagnostics;
+
+public sealed record GatewayLogScope(
+    string? SessionId = null,
+    int? WorkerProcessId = null,
+    ulong? CorrelationId = null,
+    string? CommandMethod = null,
+    string? ClientIdentity = null)
+{
+    public IReadOnlyDictionary<string, object?> ToDictionary()
+    {
+        Dictionary<string, object?> values = [];
+
+        AddIfPresent(values, "SessionId", SessionId);
+        AddIfPresent(values, "WorkerProcessId", WorkerProcessId);
+        AddIfPresent(values, "CorrelationId", CorrelationId);
+        AddIfPresent(values, "CommandMethod", CommandMethod);
+        AddIfPresent(values, "ClientIdentity", GatewayLogRedactor.RedactClientIdentity(ClientIdentity));
+
+        return values;
+    }
+
+    private static void AddIfPresent(
+        Dictionary<string, object?> values,
+        string key,
+        object? value)
+    {
+        if (value is not null)
+        {
+            values[key] = value;
+        }
+    }
+}

src/MxGateway.Server/Diagnostics/GatewayLoggerExtensions.cs

@@ -0,0 +1,16 @@
+using Microsoft.Extensions.Logging;
+
+namespace MxGateway.Server.Diagnostics;
+
+public static class GatewayLoggerExtensions
+{
+    public static IDisposable? BeginGatewayScope(
+        this ILogger logger,
+        GatewayLogScope scope)
+    {
+        ArgumentNullException.ThrowIfNull(logger);
+        ArgumentNullException.ThrowIfNull(scope);
+
+        return logger.BeginScope(scope.ToDictionary());
+    }
+}

src/MxGateway.Server/Diagnostics/GatewayRequestLoggingMiddlewareExtensions.cs

@@ -0,0 +1,57 @@
+using Microsoft.Extensions.Primitives;
+
+namespace MxGateway.Server.Diagnostics;
+
+public static class GatewayRequestLoggingMiddlewareExtensions
+{
+    public const string SessionIdHeaderName = "x-session-id";
+    public const string WorkerProcessIdHeaderName = "x-worker-process-id";
+    public const string CorrelationIdHeaderName = "x-correlation-id";
+    public const string CommandMethodHeaderName = "x-command-method";
+
+    public static IApplicationBuilder UseGatewayRequestLoggingScope(this IApplicationBuilder app)
+    {
+        ArgumentNullException.ThrowIfNull(app);
+
+        return app.Use(async (context, next) =>
+        {
+            ILogger logger = context.RequestServices
+                .GetRequiredService<ILoggerFactory>()
+                .CreateLogger("MxGateway.Request");
+
+            using IDisposable? scope = logger.BeginGatewayScope(new GatewayLogScope(
+                SessionId: ReadHeader(context, SessionIdHeaderName),
+                WorkerProcessId: ReadInt32Header(context, WorkerProcessIdHeaderName),
+                CorrelationId: ReadUInt64Header(context, CorrelationIdHeaderName),
+                CommandMethod: ReadHeader(context, CommandMethodHeaderName),
+                ClientIdentity: ReadHeader(context, "authorization")));
+
+            await next(context);
+        });
+    }
+
+    private static string? ReadHeader(HttpContext context, string headerName)
+    {
+        return context.Request.Headers.TryGetValue(headerName, out StringValues values)
+            ? values.ToString()
+            : null;
+    }
+
+    private static int? ReadInt32Header(HttpContext context, string headerName)
+    {
+        string? value = ReadHeader(context, headerName);
+
+        return int.TryParse(value, out int parsedValue)
+            ? parsedValue
+            : null;
+    }
+
+    private static ulong? ReadUInt64Header(HttpContext context, string headerName)
+    {
+        string? value = ReadHeader(context, headerName);
+
+        return ulong.TryParse(value, out ulong parsedValue)
+            ? parsedValue
+            : null;
+    }
+}

src/MxGateway.Server/GatewayApplication.cs

@@ -1,4 +1,6 @@
 using MxGateway.Contracts;
+using MxGateway.Server.Diagnostics;
+using MxGateway.Server.Metrics;
 
 namespace MxGateway.Server;
 
@@ -9,6 +11,7 @@ public static class GatewayApplication
         WebApplicationBuilder builder = CreateBuilder(args);
         WebApplication app = builder.Build();
 
+        app.UseGatewayRequestLoggingScope();
         app.MapGatewayEndpoints();
 
         return app;
@@ -19,6 +22,7 @@ public static class GatewayApplication
         WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
         builder.Services.AddHealthChecks();
+        builder.Services.AddSingleton<GatewayMetrics>();
 
         return builder;
     }

src/MxGateway.Server/Metrics/GatewayMetrics.cs

@@ -0,0 +1,306 @@
+using System.Diagnostics.Metrics;
+
+namespace MxGateway.Server.Metrics;
+
+public sealed class GatewayMetrics : IDisposable
+{
+    public const string MeterName = "MxGateway.Server";
+
+    private readonly object _syncRoot = new();
+    private readonly Meter _meter;
+    private readonly Counter<long> _sessionsOpenedCounter;
+    private readonly Counter<long> _sessionsClosedCounter;
+    private readonly Counter<long> _commandsStartedCounter;
+    private readonly Counter<long> _commandsSucceededCounter;
+    private readonly Counter<long> _commandsFailedCounter;
+    private readonly Counter<long> _eventsReceivedCounter;
+    private readonly Counter<long> _queueOverflowsCounter;
+    private readonly Counter<long> _faultsCounter;
+    private readonly Counter<long> _workerKillsCounter;
+    private readonly Counter<long> _workerExitsCounter;
+    private readonly Counter<long> _heartbeatFailuresCounter;
+    private readonly Counter<long> _streamDisconnectsCounter;
+    private readonly Histogram<double> _workerStartupLatencyHistogram;
+    private readonly Histogram<double> _commandLatencyHistogram;
+    private readonly Histogram<double> _eventStreamSendLatencyHistogram;
+    private readonly Dictionary<string, long> _commandFailuresByMethod = new(StringComparer.OrdinalIgnoreCase);
+    private readonly Dictionary<string, long> _eventsByFamily = new(StringComparer.OrdinalIgnoreCase);
+
+    private int _openSessions;
+    private int _workersRunning;
+    private int _eventQueueDepth;
+    private long _sessionsOpened;
+    private long _sessionsClosed;
+    private long _commandsStarted;
+    private long _commandsSucceeded;
+    private long _commandsFailed;
+    private long _eventsReceived;
+    private long _queueOverflows;
+    private long _faults;
+    private long _workerKills;
+    private long _workerExits;
+    private long _heartbeatFailures;
+    private long _streamDisconnects;
+    private bool _disposed;
+
+    public GatewayMetrics()
+    {
+        _meter = new Meter(MeterName, typeof(GatewayMetrics).Assembly.GetName().Version?.ToString());
+        _sessionsOpenedCounter = _meter.CreateCounter<long>("mxgateway.sessions.opened");
+        _sessionsClosedCounter = _meter.CreateCounter<long>("mxgateway.sessions.closed");
+        _commandsStartedCounter = _meter.CreateCounter<long>("mxgateway.commands.started");
+        _commandsSucceededCounter = _meter.CreateCounter<long>("mxgateway.commands.succeeded");
+        _commandsFailedCounter = _meter.CreateCounter<long>("mxgateway.commands.failed");
+        _eventsReceivedCounter = _meter.CreateCounter<long>("mxgateway.events.received");
+        _queueOverflowsCounter = _meter.CreateCounter<long>("mxgateway.queues.overflows");
+        _faultsCounter = _meter.CreateCounter<long>("mxgateway.faults");
+        _workerKillsCounter = _meter.CreateCounter<long>("mxgateway.workers.killed");
+        _workerExitsCounter = _meter.CreateCounter<long>("mxgateway.workers.exited");
+        _heartbeatFailuresCounter = _meter.CreateCounter<long>("mxgateway.heartbeats.failed");
+        _streamDisconnectsCounter = _meter.CreateCounter<long>("mxgateway.grpc.streams.disconnected");
+        _workerStartupLatencyHistogram = _meter.CreateHistogram<double>("mxgateway.workers.startup.duration", "ms");
+        _commandLatencyHistogram = _meter.CreateHistogram<double>("mxgateway.commands.duration", "ms");
+        _eventStreamSendLatencyHistogram = _meter.CreateHistogram<double>("mxgateway.events.stream_send.duration", "ms");
+
+        _meter.CreateObservableGauge("mxgateway.sessions.open", GetOpenSessions);
+        _meter.CreateObservableGauge("mxgateway.workers.running", GetWorkersRunning);
+        _meter.CreateObservableGauge("mxgateway.events.queue.depth", GetEventQueueDepth);
+    }
+
+    public void SessionOpened()
+    {
+        lock (_syncRoot)
+        {
+            _openSessions++;
+            _sessionsOpened++;
+        }
+
+        _sessionsOpenedCounter.Add(1);
+    }
+
+    public void SessionClosed()
+    {
+        lock (_syncRoot)
+        {
+            if (_openSessions > 0)
+            {
+                _openSessions--;
+            }
+
+            _sessionsClosed++;
+        }
+
+        _sessionsClosedCounter.Add(1);
+    }
+
+    public void WorkerStarted(TimeSpan startupDuration)
+    {
+        lock (_syncRoot)
+        {
+            _workersRunning++;
+        }
+
+        _workerStartupLatencyHistogram.Record(startupDuration.TotalMilliseconds);
+    }
+
+    public void WorkerStopped(string reason)
+    {
+        lock (_syncRoot)
+        {
+            if (_workersRunning > 0)
+            {
+                _workersRunning--;
+            }
+
+            _workerExits++;
+        }
+
+        _workerExitsCounter.Add(1, new KeyValuePair<string, object?>("reason", reason));
+    }
+
+    public void WorkerKilled(string reason)
+    {
+        lock (_syncRoot)
+        {
+            _workerKills++;
+        }
+
+        _workerKillsCounter.Add(1, new KeyValuePair<string, object?>("reason", reason));
+    }
+
+    public void CommandStarted(string method)
+    {
+        lock (_syncRoot)
+        {
+            _commandsStarted++;
+        }
+
+        _commandsStartedCounter.Add(1, new KeyValuePair<string, object?>("method", method));
+    }
+
+    public void CommandSucceeded(string method, TimeSpan duration)
+    {
+        lock (_syncRoot)
+        {
+            _commandsSucceeded++;
+        }
+
+        KeyValuePair<string, object?> methodTag = new("method", method);
+        _commandsSucceededCounter.Add(1, methodTag);
+        _commandLatencyHistogram.Record(duration.TotalMilliseconds, methodTag);
+    }
+
+    public void CommandFailed(string method, string category, TimeSpan duration)
+    {
+        lock (_syncRoot)
+        {
+            _commandsFailed++;
+            Increment(_commandFailuresByMethod, method);
+        }
+
+        KeyValuePair<string, object?> methodTag = new("method", method);
+        KeyValuePair<string, object?> categoryTag = new("category", category);
+        _commandsFailedCounter.Add(1, methodTag, categoryTag);
+        _commandLatencyHistogram.Record(duration.TotalMilliseconds, methodTag, categoryTag);
+    }
+
+    public void EventReceived(string sessionId, string family)
+    {
+        lock (_syncRoot)
+        {
+            _eventsReceived++;
+            Increment(_eventsByFamily, family);
+        }
+
+        _eventsReceivedCounter.Add(
+            1,
+            new KeyValuePair<string, object?>("session_id", sessionId),
+            new KeyValuePair<string, object?>("family", family));
+    }
+
+    public void RecordEventStreamSend(string family, TimeSpan duration)
+    {
+        _eventStreamSendLatencyHistogram.Record(
+            duration.TotalMilliseconds,
+            new KeyValuePair<string, object?>("family", family));
+    }
+
+    public void SetEventQueueDepth(int depth)
+    {
+        if (depth < 0)
+        {
+            throw new ArgumentOutOfRangeException(nameof(depth), depth, "Queue depth cannot be negative.");
+        }
+
+        lock (_syncRoot)
+        {
+            _eventQueueDepth = depth;
+        }
+    }
+
+    public void QueueOverflow(string queueName)
+    {
+        lock (_syncRoot)
+        {
+            _queueOverflows++;
+        }
+
+        _queueOverflowsCounter.Add(1, new KeyValuePair<string, object?>("queue", queueName));
+    }
+
+    public void Fault(string category)
+    {
+        lock (_syncRoot)
+        {
+            _faults++;
+        }
+
+        _faultsCounter.Add(1, new KeyValuePair<string, object?>("category", category));
+    }
+
+    public void HeartbeatFailed(string sessionId)
+    {
+        lock (_syncRoot)
+        {
+            _heartbeatFailures++;
+        }
+
+        _heartbeatFailuresCounter.Add(1, new KeyValuePair<string, object?>("session_id", sessionId));
+    }
+
+    public void StreamDisconnected(string reason)
+    {
+        lock (_syncRoot)
+        {
+            _streamDisconnects++;
+        }
+
+        _streamDisconnectsCounter.Add(1, new KeyValuePair<string, object?>("reason", reason));
+    }
+
+    public GatewayMetricsSnapshot GetSnapshot()
+    {
+        lock (_syncRoot)
+        {
+            return new GatewayMetricsSnapshot(
+                OpenSessions: _openSessions,
+                WorkersRunning: _workersRunning,
+                EventQueueDepth: _eventQueueDepth,
+                SessionsOpened: _sessionsOpened,
+                SessionsClosed: _sessionsClosed,
+                CommandsStarted: _commandsStarted,
+                CommandsSucceeded: _commandsSucceeded,
+                CommandsFailed: _commandsFailed,
+                EventsReceived: _eventsReceived,
+                QueueOverflows: _queueOverflows,
+                Faults: _faults,
+                WorkerKills: _workerKills,
+                WorkerExits: _workerExits,
+                HeartbeatFailures: _heartbeatFailures,
+                StreamDisconnects: _streamDisconnects,
+                CommandFailuresByMethod: new Dictionary<string, long>(_commandFailuresByMethod, StringComparer.OrdinalIgnoreCase),
+                EventsByFamily: new Dictionary<string, long>(_eventsByFamily, StringComparer.OrdinalIgnoreCase));
+        }
+    }
+
+    public void Dispose()
+    {
+        if (_disposed)
+        {
+            return;
+        }
+
+        _meter.Dispose();
+        _disposed = true;
+    }
+
+    private int GetOpenSessions()
+    {
+        lock (_syncRoot)
+        {
+            return _openSessions;
+        }
+    }
+
+    private int GetWorkersRunning()
+    {
+        lock (_syncRoot)
+        {
+            return _workersRunning;
+        }
+    }
+
+    private int GetEventQueueDepth()
+    {
+        lock (_syncRoot)
+        {
+            return _eventQueueDepth;
+        }
+    }
+
+    private static void Increment(Dictionary<string, long> values, string key)
+    {
+        values.TryGetValue(key, out long currentValue);
+        values[key] = currentValue + 1;
+    }
+}

src/MxGateway.Server/Metrics/GatewayMetricsSnapshot.cs

@@ -0,0 +1,20 @@
+namespace MxGateway.Server.Metrics;
+
+public sealed record GatewayMetricsSnapshot(
+    int OpenSessions,
+    int WorkersRunning,
+    int EventQueueDepth,
+    long SessionsOpened,
+    long SessionsClosed,
+    long CommandsStarted,
+    long CommandsSucceeded,
+    long CommandsFailed,
+    long EventsReceived,
+    long QueueOverflows,
+    long Faults,
+    long WorkerKills,
+    long WorkerExits,
+    long HeartbeatFailures,
+    long StreamDisconnects,
+    IReadOnlyDictionary<string, long> CommandFailuresByMethod,
+    IReadOnlyDictionary<string, long> EventsByFamily);

src/MxGateway.Tests/Contracts/ProtobufContractRoundTripTests.cs

@@ -1,195 +0,0 @@
-using Google.Protobuf;
-using Google.Protobuf.WellKnownTypes;
-using MxGateway.Contracts;
-using MxGateway.Contracts.Proto;
-
-namespace MxGateway.Tests.Contracts;
-
-public sealed class ProtobufContractRoundTripTests
-{
-    [Fact]
-    public void GatewayDescriptor_ContainsInitialPublicServiceMethods()
-    {
-        var service = Assert.Single(
-            MxaccessGatewayReflection.Descriptor.Services,
-            descriptor => descriptor.Name == "MxAccessGateway");
-
-        Assert.Contains(service.Methods, method => method.Name == "OpenSession");
-        Assert.Contains(service.Methods, method => method.Name == "CloseSession");
-        Assert.Contains(service.Methods, method => method.Name == "Invoke");
-        Assert.Contains(service.Methods, method => method.Name == "StreamEvents");
-    }
-
-    [Fact]
-    public void WorkerEnvelopeDescriptor_ContainsRequiredCorrelationFields()
-    {
-        var fields = WorkerEnvelope.Descriptor.Fields.InDeclarationOrder();
-
-        Assert.Contains(fields, field => field.Name == "protocol_version");
-        Assert.Contains(fields, field => field.Name == "session_id");
-        Assert.Contains(fields, field => field.Name == "sequence");
-        Assert.Contains(fields, field => field.Name == "correlation_id");
-    }
-
-    [Fact]
-    public void CommandRequest_RoundTripsMethodSpecificPayload()
-    {
-        var original = new MxCommandRequest
-        {
-            SessionId = "session-1",
-            ClientCorrelationId = "client-correlation-1",
-            Command = new MxCommand
-            {
-                Kind = MxCommandKind.Register,
-                Register = new RegisterCommand
-                {
-                    ClientName = "mxaccessgw-test-client",
-                },
-            },
-        };
-
-        var parsed = MxCommandRequest.Parser.ParseFrom(original.ToByteArray());
-
-        Assert.Equal(original, parsed);
-        Assert.Equal(MxCommand.PayloadOneofCase.Register, parsed.Command.PayloadCase);
-    }
-
-    [Fact]
-    public void CommandReply_RoundTripsHResultReturnValueOutParamsAndStatuses()
-    {
-        var original = new MxCommandReply
-        {
-            SessionId = "session-1",
-            CorrelationId = "gateway-correlation-1",
-            Kind = MxCommandKind.AddItem,
-            ProtocolStatus = new ProtocolStatus
-            {
-                Code = ProtocolStatusCode.Ok,
-            },
-            Hresult = 0,
-            ReturnValue = new MxValue
-            {
-                DataType = MxDataType.Integer,
-                Int32Value = 1234,
-                VariantType = "VT_I4",
-            },
-            AddItem = new AddItemReply
-            {
-                ItemHandle = 1234,
-            },
-        };
-        original.Statuses.Add(new MxStatusProxy
-        {
-            Success = 1,
-            Category = MxStatusCategory.Ok,
-            DetectedBy = MxStatusSource.RespondingLmx,
-            Detail = 0,
-        });
-
-        var parsed = MxCommandReply.Parser.ParseFrom(original.ToByteArray());
-
-        Assert.Equal(original, parsed);
-        Assert.True(parsed.HasHresult);
-        Assert.Equal(MxCommandReply.PayloadOneofCase.AddItem, parsed.PayloadCase);
-        Assert.Single(parsed.Statuses);
-    }
-
-    [Fact]
-    public void Event_RoundTripsValueStatusSequenceAndBufferedBody()
-    {
-        var timestamp = Timestamp.FromDateTime(new DateTime(2026, 4, 26, 20, 0, 0, DateTimeKind.Utc));
-        var original = new MxEvent
-        {
-            Family = MxEventFamily.OnBufferedDataChange,
-            SessionId = "session-1",
-            ServerHandle = 10,
-            ItemHandle = 20,
-            Value = new MxValue
-            {
-                DataType = MxDataType.Float,
-                ArrayValue = new MxArray
-                {
-                    ElementDataType = MxDataType.Float,
-                    FloatValues = new FloatArray
-                    {
-                        Values = { 1.5f, 2.5f },
-                    },
-                    Dimensions = { 2 },
-                    VariantType = "VT_ARRAY|VT_R4",
-                },
-            },
-            Quality = 192,
-            SourceTimestamp = timestamp,
-            WorkerSequence = 42,
-            WorkerTimestamp = timestamp,
-            GatewayReceiveTimestamp = timestamp,
-            OnBufferedDataChange = new OnBufferedDataChangeEvent
-            {
-                DataType = MxDataType.Float,
-                QualityValues = new MxArray
-                {
-                    ElementDataType = MxDataType.Integer,
-                    Int32Values = new Int32Array
-                    {
-                        Values = { 192, 192 },
-                    },
-                    Dimensions = { 2 },
-                },
-                TimestampValues = new MxArray
-                {
-                    ElementDataType = MxDataType.Time,
-                    TimestampValues = new TimestampArray
-                    {
-                        Values = { timestamp, timestamp },
-                    },
-                    Dimensions = { 2 },
-                },
-            },
-        };
-        original.Statuses.Add(new MxStatusProxy
-        {
-            Success = 1,
-            Category = MxStatusCategory.Ok,
-            DetectedBy = MxStatusSource.RespondingNmx,
-            Detail = 0,
-        });
-
-        var parsed = MxEvent.Parser.ParseFrom(original.ToByteArray());
-
-        Assert.Equal(original, parsed);
-        Assert.Equal(MxEvent.BodyOneofCase.OnBufferedDataChange, parsed.BodyCase);
-        Assert.Single(parsed.Statuses);
-    }
-
-    [Fact]
-    public void WorkerEnvelope_RoundTripsProtocolFieldsAndCommandBody()
-    {
-        var original = new WorkerEnvelope
-        {
-            ProtocolVersion = GatewayContractInfo.WorkerProtocolVersion,
-            SessionId = "session-1",
-            Sequence = 7,
-            CorrelationId = "gateway-correlation-1",
-            WorkerCommand = new WorkerCommand
-            {
-                EnqueueTimestamp = Timestamp.FromDateTime(
-                    new DateTime(2026, 4, 26, 20, 5, 0, DateTimeKind.Utc)),
-                Command = new MxCommand
-                {
-                    Kind = MxCommandKind.Advise,
-                    Advise = new AdviseCommand
-                    {
-                        ServerHandle = 10,
-                        ItemHandle = 20,
-                    },
-                },
-            },
-        };
-
-        var parsed = WorkerEnvelope.Parser.ParseFrom(original.ToByteArray());
-
-        Assert.Equal(original, parsed);
-        Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerCommand, parsed.BodyCase);
-        Assert.Equal(MxCommand.PayloadOneofCase.Advise, parsed.WorkerCommand.Command.PayloadCase);
-    }
-}

src/MxGateway.Tests/Diagnostics/GatewayLogRedactorTests.cs

@@ -0,0 +1,73 @@
+using MxGateway.Server.Diagnostics;
+
+namespace MxGateway.Tests.Diagnostics;
+
+public sealed class GatewayLogRedactorTests
+{
+    [Fact]
+    public void RedactApiKey_PreservesKeyIdAndRemovesSecret()
+    {
+        string? redacted = GatewayLogRedactor.RedactApiKey("Bearer mxgw_operator01_super-secret");
+
+        Assert.Equal("Bearer mxgw_operator01_[redacted]", redacted);
+        Assert.DoesNotContain("super-secret", redacted);
+    }
+
+    [Theory]
+    [InlineData("AuthenticateUser")]
+    [InlineData("WriteSecured")]
+    [InlineData("WriteSecured2")]
+    public void IsCredentialBearingCommand_IdentifiesSensitiveMxAccessCommands(string commandMethod)
+    {
+        Assert.True(GatewayLogRedactor.IsCredentialBearingCommand(commandMethod));
+    }
+
+    [Fact]
+    public void RedactCommandValue_DoesNotLogRawValuesByDefault()
+    {
+        object? redacted = GatewayLogRedactor.RedactCommandValue("Write", "plaintext-tag-value");
+
+        Assert.Equal("[redacted]", redacted);
+    }
+
+    [Fact]
+    public void RedactCommandValue_RedactsSecuredWriteEvenWhenValueLoggingIsEnabled()
+    {
+        object? redacted = GatewayLogRedactor.RedactCommandValue(
+            "WriteSecured",
+            "credential-bearing-value",
+            valueLoggingEnabled: true);
+
+        Assert.Equal("[redacted]", redacted);
+    }
+
+    [Fact]
+    public void RedactCommandValue_AllowsNonSensitiveValueOnlyWhenValueLoggingIsEnabled()
+    {
+        object? redacted = GatewayLogRedactor.RedactCommandValue(
+            "Write",
+            "diagnostic-value",
+            valueLoggingEnabled: true);
+
+        Assert.Equal("diagnostic-value", redacted);
+    }
+
+    [Fact]
+    public void LogScope_RedactsClientIdentityBeforeScopeStateIsCreated()
+    {
+        GatewayLogScope scope = new(
+            SessionId: "session-1",
+            WorkerProcessId: 1234,
+            CorrelationId: 99,
+            CommandMethod: "AuthenticateUser",
+            ClientIdentity: "Bearer mxgw_admin_secret");
+
+        IReadOnlyDictionary<string, object?> values = scope.ToDictionary();
+
+        Assert.Equal("session-1", values["SessionId"]);
+        Assert.Equal(1234, values["WorkerProcessId"]);
+        Assert.Equal((ulong)99, values["CorrelationId"]);
+        Assert.Equal("AuthenticateUser", values["CommandMethod"]);
+        Assert.Equal("Bearer mxgw_admin_[redacted]", values["ClientIdentity"]);
+    }
+}

src/MxGateway.Tests/Gateway/GatewayApplicationTests.cs

@@ -1,6 +1,8 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.DependencyInjection;
 using MxGateway.Server;
+using MxGateway.Server.Metrics;
 
 namespace MxGateway.Tests.Gateway;
 
@@ -19,4 +21,14 @@ public sealed class GatewayApplicationTests
 
         Assert.Equal("LiveHealth", endpoint.Metadata.GetMetadata<IEndpointNameMetadata>()?.EndpointName);
     }
+
+    [Fact]
+    public void Build_RegistersGatewayMetrics()
+    {
+        WebApplication app = GatewayApplication.Build([]);
+
+        GatewayMetrics metrics = app.Services.GetRequiredService<GatewayMetrics>();
+
+        Assert.NotNull(metrics);
+    }
 }

src/MxGateway.Tests/Metrics/GatewayMetricsTests.cs

@@ -0,0 +1,60 @@
+using MxGateway.Server.Metrics;
+
+namespace MxGateway.Tests.Metrics;
+
+public sealed class GatewayMetricsTests
+{
+    [Fact]
+    public void GetSnapshot_ReflectsSessionWorkerCommandEventAndFaultUpdates()
+    {
+        using GatewayMetrics metrics = new();
+
+        metrics.SessionOpened();
+        metrics.WorkerStarted(TimeSpan.FromMilliseconds(250));
+        metrics.CommandStarted("Register");
+        metrics.CommandSucceeded("Register", TimeSpan.FromMilliseconds(10));
+        metrics.CommandStarted("WriteSecured");
+        metrics.CommandFailed("WriteSecured", "AuthorizationFailed", TimeSpan.FromMilliseconds(12));
+        metrics.EventReceived("session-1", "OnDataChange");
+        metrics.EventReceived("session-1", "OnDataChange");
+        metrics.SetEventQueueDepth(7);
+        metrics.QueueOverflow("session-events");
+        metrics.Fault("CommandTimeout");
+        metrics.WorkerKilled("CommandTimeout");
+        metrics.WorkerStopped("Killed");
+        metrics.HeartbeatFailed("session-1");
+        metrics.StreamDisconnected("ClientCancelled");
+        metrics.SessionClosed();
+
+        GatewayMetricsSnapshot snapshot = metrics.GetSnapshot();
+
+        Assert.Equal(0, snapshot.OpenSessions);
+        Assert.Equal(0, snapshot.WorkersRunning);
+        Assert.Equal(7, snapshot.EventQueueDepth);
+        Assert.Equal(1, snapshot.SessionsOpened);
+        Assert.Equal(1, snapshot.SessionsClosed);
+        Assert.Equal(2, snapshot.CommandsStarted);
+        Assert.Equal(1, snapshot.CommandsSucceeded);
+        Assert.Equal(1, snapshot.CommandsFailed);
+        Assert.Equal(2, snapshot.EventsReceived);
+        Assert.Equal(1, snapshot.QueueOverflows);
+        Assert.Equal(1, snapshot.Faults);
+        Assert.Equal(1, snapshot.WorkerKills);
+        Assert.Equal(1, snapshot.WorkerExits);
+        Assert.Equal(1, snapshot.HeartbeatFailures);
+        Assert.Equal(1, snapshot.StreamDisconnects);
+        Assert.Equal(1, snapshot.CommandFailuresByMethod["WriteSecured"]);
+        Assert.Equal(2, snapshot.EventsByFamily["OnDataChange"]);
+    }
+
+    [Fact]
+    public void SetEventQueueDepth_RejectsNegativeDepth()
+    {
+        using GatewayMetrics metrics = new();
+
+        ArgumentOutOfRangeException exception = Assert.Throws<ArgumentOutOfRangeException>(
+            () => metrics.SetEventQueueDepth(-1));
+
+        Assert.Equal("depth", exception.ParamName);
+    }
+}