feat(sessions): record OwnerKeyId on session creation

Add a nullable string? OwnerKeyId property to GatewaySession that captures
the API key identifier (KeyId) of the authenticated caller that opened the
session. Wire it through ISessionManager.OpenSessionAsync → SessionManager
→ GatewaySession constructor. The gRPC service passes identityAccessor
.Current?.KeyId; internal callers (GatewayAlarmMonitor, DashboardLiveDataService)
pass null. Covers the positive and null cases with two new TDD-first tests.

src/ZB.MOM.WW.MxGateway.Server/Alarms/GatewayAlarmMonitor.cs

@@ -203,6 +203,7 @@ public sealed class GatewayAlarmMonitor : BackgroundService, IGatewayAlarmServic
         GatewaySession session = await _sessionManager.OpenSessionAsync(
                 new SessionOpenRequest(BackendName, MonitorClientName, Guid.NewGuid().ToString("N"), CommandTimeout: null),
                 MonitorClientName,
+                ownerKeyId: null,
                 stoppingToken)
             .ConfigureAwait(false);
         lock (_sync) { _session = session; }

src/ZB.MOM.WW.MxGateway.Server/Dashboard/DashboardLiveDataService.cs

@@ -138,6 +138,7 @@ public sealed class DashboardLiveDataService : IDashboardLiveDataService, IAsync
         GatewaySession session = await _sessionManager.OpenSessionAsync(
                 new SessionOpenRequest(BackendName, ClientName, Guid.NewGuid().ToString("N"), CommandTimeout: null),
                 ClientName,
+                ownerKeyId: null,
                 cancellationToken)
             .ConfigureAwait(false);
 

src/ZB.MOM.WW.MxGateway.Server/Grpc/MxAccessGatewayService.cs

@@ -36,6 +36,7 @@ public sealed class MxAccessGatewayService(
                 .OpenSessionAsync(
                     SessionOpenRequest.FromContract(request),
                     ResolveClientIdentity(),
+                    identityAccessor.Current?.KeyId,
                     context.CancellationToken)
                 .ConfigureAwait(false);
 

src/ZB.MOM.WW.MxGateway.Server/Sessions/GatewaySession.cs

@@ -48,6 +48,7 @@ public sealed class GatewaySession
             pipeName,
             nonce,
             clientIdentity,
+            ownerKeyId: null,
             clientSessionName,
             clientCorrelationId,
             commandTimeout,
@@ -66,6 +67,7 @@ public sealed class GatewaySession
     /// <param name="pipeName">Name of the named pipe for gateway-worker IPC.</param>
     /// <param name="nonce">Security nonce for worker validation.</param>
     /// <param name="clientIdentity">Client identity from the authentication context.</param>
+    /// <param name="ownerKeyId">API key identifier of the caller that created this session.</param>
     /// <param name="clientSessionName">Client-supplied session name.</param>
     /// <param name="clientCorrelationId">Client-supplied correlation identifier.</param>
     /// <param name="commandTimeout">Timeout for command invocation.</param>
@@ -79,6 +81,7 @@ public sealed class GatewaySession
         string pipeName,
         string nonce,
         string? clientIdentity,
+        string? ownerKeyId,
         string? clientSessionName,
         string? clientCorrelationId,
         TimeSpan commandTimeout,
@@ -112,6 +115,7 @@ public sealed class GatewaySession
         PipeName = pipeName;
         Nonce = nonce;
         ClientIdentity = clientIdentity;
+        OwnerKeyId = ownerKeyId;
         ClientSessionName = clientSessionName;
         ClientCorrelationId = clientCorrelationId;
         CommandTimeout = commandTimeout;
@@ -148,6 +152,11 @@ public sealed class GatewaySession
     /// </summary>
     public string? ClientIdentity { get; }
 
+    /// <summary>
+    /// Gets the API key identifier of the caller that created this session.
+    /// </summary>
+    public string? OwnerKeyId { get; }
+
     /// <summary>
     /// Gets the client-supplied session name.
     /// </summary>

src/ZB.MOM.WW.MxGateway.Server/Sessions/ISessionManager.cs

@@ -8,11 +8,13 @@ public interface ISessionManager
     /// <summary>Opens a new gateway session and launches a worker process.</summary>
     /// <param name="request">Request payload.</param>
     /// <param name="clientIdentity">Client identity string.</param>
+    /// <param name="ownerKeyId">API key identifier of the caller creating the session.</param>
     /// <param name="cancellationToken">Token to cancel the asynchronous operation.</param>
     /// <returns>The newly opened session.</returns>
     Task<GatewaySession> OpenSessionAsync(
         SessionOpenRequest request,
         string? clientIdentity,
+        string? ownerKeyId,
         CancellationToken cancellationToken);
 
     /// <summary>Attempts to retrieve a session by ID.</summary>

src/ZB.MOM.WW.MxGateway.Server/Sessions/SessionManager.cs

@@ -58,11 +58,13 @@ public sealed class SessionManager : ISessionManager
     /// </summary>
     /// <param name="request">Session open request.</param>
     /// <param name="clientIdentity">Client authentication identity.</param>
+    /// <param name="ownerKeyId">API key identifier of the caller creating the session.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
     /// <returns>Opened gateway session.</returns>
     public async Task<GatewaySession> OpenSessionAsync(
         SessionOpenRequest request,
         string? clientIdentity,
+        string? ownerKeyId,
         CancellationToken cancellationToken)
     {
         ArgumentNullException.ThrowIfNull(request);
@@ -72,7 +74,7 @@ public sealed class SessionManager : ISessionManager
         bool sessionOpenedRecorded = false;
         try
         {
-            session = CreateSession(request, clientIdentity);
+            session = CreateSession(request, clientIdentity, ownerKeyId);
             if (!_registry.TryAdd(session))
             {
                 throw new SessionManagerException(
@@ -420,7 +422,8 @@ public sealed class SessionManager : ISessionManager
 
     private GatewaySession CreateSession(
         SessionOpenRequest request,
-        string? clientIdentity)
+        string? clientIdentity,
+        string? ownerKeyId)
     {
         string sessionId = CreateSessionId();
         string backendName = string.IsNullOrWhiteSpace(request.RequestedBackend)
@@ -441,6 +444,7 @@ public sealed class SessionManager : ISessionManager
             pipeName,
             nonce,
             clientIdentity,
+            ownerKeyId,
             request.ClientSessionName,
             clientCorrelationId,
             commandTimeout,