perf(worker): launcher-configurable event queue capacity

src/ZB.MOM.WW.MxGateway.Tests/Configuration/GatewayOptionsValidatorTests.cs

@@ -1099,4 +1099,59 @@ public sealed class GatewayOptionsValidatorTests
         Assert.True(result.Failed);
         Assert.Contains(result.Failures!, f => f.Contains("MaxMessageBytes") && f.Contains("reserve"));
     }
+
+    /// <summary>
+    /// Verifies the shipped worker event-queue capacity default passes validation and still matches
+    /// the worker-side <c>MxAccessEventQueue.DefaultCapacity</c> the environment variable falls back
+    /// to when the launcher value is unusable.
+    /// </summary>
+    [Fact]
+    public void Validate_Succeeds_WithDefaultEventQueueCapacity()
+    {
+        Assert.Equal(10000, new WorkerOptions().EventQueueCapacity);
+
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(null, ValidOptions());
+        Assert.True(result.Succeeded);
+    }
+
+    /// <summary>
+    /// Verifies a worker event-queue capacity outside the supported range fails validation. Too
+    /// small leaves no burst headroom (an overflow faults the whole session); too large commits the
+    /// 32-bit worker to an outsized pre-allocation.
+    /// </summary>
+    /// <param name="eventQueueCapacity">Capacity under test.</param>
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-1)]
+    [InlineData(999)]
+    [InlineData(1_000_001)]
+    public void Validate_Fails_WhenEventQueueCapacityOutOfRange(int eventQueueCapacity)
+    {
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(
+            null,
+            WithWorkerAndProtocol(
+                new WorkerOptions { EventQueueCapacity = eventQueueCapacity },
+                new ProtocolOptions()));
+
+        Assert.True(result.Failed);
+        Assert.Contains(
+            result.Failures!,
+            f => f.Contains("MxGateway:Worker:EventQueueCapacity", StringComparison.Ordinal));
+    }
+
+    /// <summary>Verifies the worker event-queue capacity bounds themselves are accepted.</summary>
+    /// <param name="eventQueueCapacity">Capacity under test.</param>
+    [Theory]
+    [InlineData(1000)]
+    [InlineData(1_000_000)]
+    public void Validate_Succeeds_AtEventQueueCapacityBounds(int eventQueueCapacity)
+    {
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(
+            null,
+            WithWorkerAndProtocol(
+                new WorkerOptions { EventQueueCapacity = eventQueueCapacity },
+                new ProtocolOptions()));
+
+        Assert.True(result.Succeeded);
+    }
 }