Improve gateway reliability and dashboard docs

src/MxGateway.Tests/Metrics/GatewayMetricsTests.cs

@@ -17,7 +17,8 @@ public sealed class GatewayMetricsTests
         metrics.CommandFailed("WriteSecured", "AuthorizationFailed", TimeSpan.FromMilliseconds(12));
         metrics.EventReceived("session-1", "OnDataChange");
         metrics.EventReceived("session-1", "OnDataChange");
-        metrics.SetEventQueueDepth(7);
+        metrics.SetWorkerEventQueueDepth(7);
+        metrics.SetGrpcEventStreamQueueDepth(3);
         metrics.QueueOverflow("session-events");
         metrics.Fault("CommandTimeout");
         metrics.WorkerKilled("CommandTimeout");
@@ -30,7 +31,8 @@ public sealed class GatewayMetricsTests
 
         Assert.Equal(0, snapshot.OpenSessions);
         Assert.Equal(0, snapshot.WorkersRunning);
-        Assert.Equal(7, snapshot.EventQueueDepth);
+        Assert.Equal(7, snapshot.WorkerEventQueueDepth);
+        Assert.Equal(3, snapshot.GrpcEventStreamQueueDepth);
         Assert.Equal(1, snapshot.SessionsOpened);
         Assert.Equal(1, snapshot.SessionsClosed);
         Assert.Equal(2, snapshot.CommandsStarted);
@@ -45,6 +47,7 @@ public sealed class GatewayMetricsTests
         Assert.Equal(1, snapshot.StreamDisconnects);
         Assert.Equal(1, snapshot.CommandFailuresByMethod["WriteSecured"]);
         Assert.Equal(2, snapshot.EventsByFamily["OnDataChange"]);
+        Assert.Equal(2, snapshot.EventsBySession["session-1"]);
     }
 
     [Fact]
@@ -53,7 +56,7 @@ public sealed class GatewayMetricsTests
         using GatewayMetrics metrics = new();
 
         ArgumentOutOfRangeException exception = Assert.Throws<ArgumentOutOfRangeException>(
-            () => metrics.SetEventQueueDepth(-1));
+            () => metrics.SetWorkerEventQueueDepth(-1));
 
         Assert.Equal("depth", exception.ParamName);
     }