diff --git a/src/Observability/Runtime/Builder.cs b/src/Observability/Runtime/Builder.cs
index c237520d..f8985619 100644
--- a/src/Observability/Runtime/Builder.cs
+++ b/src/Observability/Runtime/Builder.cs
@@ -98,6 +98,7 @@ private void EnsureBuilt()
                 tracerProviderBuilder.Build();
             }
 
+            EnvironmentUtils.Initialize(configuration: this.Configuration);
             _isBuilt = true;
         }
 
diff --git a/src/Observability/Runtime/Common/Agent365EndpointDiscovery.cs b/src/Observability/Runtime/Common/Agent365EndpointDiscovery.cs
new file mode 100644
index 00000000..2d4704ef
--- /dev/null
+++ b/src/Observability/Runtime/Common/Agent365EndpointDiscovery.cs
@@ -0,0 +1,41 @@
+// ------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// ------------------------------------------------------------------------------
+
+using System;
+
+namespace Microsoft.Agents.A365.Observability.Runtime.Common
+{
+    /// <summary>
+    /// Provides discovery for Agent365 endpoints.
+    /// </summary>
+    public sealed class Agent365EndpointDiscovery
+    {
+        private readonly string clusterCategory;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Agent365EndpointDiscovery"/> class.
+        /// </summary>
+        /// <param name="clusterCategory">The cluster category.</param>
+        public Agent365EndpointDiscovery(string clusterCategory)
+        {
+            this.clusterCategory = clusterCategory ?? "production";
+        }
+
+        /// <summary>
+        /// Gets the base host for the specified cluster category.
+        /// </summary>
+        public string GetHost()
+        {
+            switch (this.clusterCategory?.ToLowerInvariant())
+            {
+                case "firstrelease":
+                case "production":
+                case "prod":
+                    return "agent365.svc.cloud.microsoft";
+                default:
+                    throw new ArgumentException($"Invalid ClusterCategory value: {clusterCategory}");
+            }
+        }
+    }
+}
diff --git a/src/Observability/Runtime/Common/EnvironmentUtils.cs b/src/Observability/Runtime/Common/EnvironmentUtils.cs
index fb3f7f31..fab0bbfc 100644
--- a/src/Observability/Runtime/Common/EnvironmentUtils.cs
+++ b/src/Observability/Runtime/Common/EnvironmentUtils.cs
@@ -2,6 +2,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // ------------------------------------------------------------------------------
 
+using Microsoft.Extensions.Configuration;
 using System;
 
 namespace Microsoft.Agents.A365.Observability.Runtime.Common
@@ -14,6 +15,9 @@ public class EnvironmentUtils
         private const string ProdObservabilityScope = "https://api.powerplatform.com/.default";
         private const string ProdObservabilityClusterCategory = "prod";
         private const string DevelopmentEnvironmentName = "development";
+        private const string Agent365EndpointProdObservabilityScope = "api://9b975845-388f-4429-889e-eab1ef63949c/.default";
+        private static bool _initialized;
+        private static bool _customDomainEnabled;
 
         /// <summary>
         /// Returns the scope for authenticating to the observability service based on the current environment.
@@ -21,19 +25,7 @@ public class EnvironmentUtils
         /// <returns>The authentication scope.</returns>
         public static string[] GetObservabilityAuthenticationScope()
         {
-            return new[] { ProdObservabilityScope };
-        }
-
-        /// <summary>
-        /// [Deprecated] Returns the scope for authenticating to the observability service based on the cluster category.
-        /// </summary>
-        /// <param name="clusterCategory">Cluster category (deprecated, defaults to production).</param>
-        /// <returns>The authentication scope.</returns>
-        [Obsolete("Cluster category argument is deprecated and will be removed in future versions. Defaults to production.")]
-        public static string[] GetObservabilityAuthenticationScope(string clusterCategory = ProdObservabilityClusterCategory)
-        {
-            // clusterCategory is ignored; always returns production scope
-            return new[] { ProdObservabilityScope };
+            return IsCustomDomainEnabled() ? new[] { Agent365EndpointProdObservabilityScope } : new[] { ProdObservabilityScope };
         }
 
         /// <summary>
@@ -66,6 +58,40 @@ public static bool IsDevelopmentEnvironment()
             return string.Equals(environment, DevelopmentEnvironmentName, StringComparison.OrdinalIgnoreCase);
         }
 
+        /// <summary>
+        /// Initializes the cached configuration values for environment utilities. Should be called once at application startup.
+        /// </summary>
+        /// <param name="configuration">The configuration instance.</param>
+        /// <param name="force">When true, re-initializes even if already initialized.</param>
+        public static void Initialize(IConfiguration? configuration, bool force = false)
+        {
+            if (configuration == null)
+            {
+                throw new ArgumentNullException(nameof(configuration));
+            }
+
+            if (_initialized && !force)
+            {
+                return;
+            }
+
+            string enabled = configuration["EnableAgent365CustomDomain"] ?? string.Empty;
+            _customDomainEnabled = enabled.Equals(bool.TrueString, StringComparison.OrdinalIgnoreCase);
+            _initialized = true;
+        }
+
+        /// <summary>
+        /// Returns true if the custom domain feature is enabled.
+        /// </summary>
+        public static bool IsCustomDomainEnabled()
+        {
+            if (!_initialized)
+            {
+                throw new InvalidOperationException("EnvironmentUtils is not initialized. Call Initialize() before using this method.");
+            }
+            return _customDomainEnabled;
+        }
+
         /// <summary>
         /// Gets the current environment name.
         /// </summary>
diff --git a/src/Observability/Runtime/Tracing/Exporters/Agent365ExporterCore.cs b/src/Observability/Runtime/Tracing/Exporters/Agent365ExporterCore.cs
index bab1a631..3615b000 100644
--- a/src/Observability/Runtime/Tracing/Exporters/Agent365ExporterCore.cs
+++ b/src/Observability/Runtime/Tracing/Exporters/Agent365ExporterCore.cs
@@ -4,6 +4,7 @@
 
 using Microsoft.Agents.A365.Observability.Runtime.Common;
 using Microsoft.Agents.A365.Observability.Runtime.Tracing.Scopes;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using OpenTelemetry;
@@ -26,6 +27,7 @@ namespace Microsoft.Agents.A365.Observability.Runtime.Tracing.Exporters
     public class Agent365ExporterCore
     {
         private const string CorrelationIdHeaderKey = "x-ms-correlation-id";
+        private const string TenantIdHeaderKey = "x-ms-tenant-id";
         private readonly ExportFormatter _formatter;
         private readonly ILogger<Agent365ExporterCore> _logger;
 
@@ -86,9 +88,11 @@ public Agent365ExporterCore(ExportFormatter formatter, ILogger<Agent365ExporterC
         /// <returns>The endpoint path string.</returns>
         public string BuildEndpointPath(string agentId, bool useS2SEndpoint)
         {
-            return useS2SEndpoint
-                ? $"/maven/agent365/service/agents/{agentId}/traces"
-                : $"/maven/agent365/agents/{agentId}/traces";
+            return EnvironmentUtils.IsCustomDomainEnabled()
+                ? $"/agents/{agentId}/traces"
+                : useS2SEndpoint
+                    ? $"/maven/agent365/service/agents/{agentId}/traces"
+                    : $"/maven/agent365/agents/{agentId}/traces";
         }
 
         /// <summary>
@@ -97,7 +101,7 @@ public string BuildEndpointPath(string agentId, bool useS2SEndpoint)
         /// <param name="endpoint">The base endpoint.</param>
         /// <param name="endpointPath">The endpoint path.</param>
         /// <returns>The full request URI string.</returns>
-        public string BuildRequestUri(string endpoint, string endpointPath)
+        public static string BuildRequestUri(string endpoint, string endpointPath)
         {
             return $"https://{endpoint}{endpointPath}?api-version=1";
         }
@@ -124,11 +128,11 @@ public async Task<ExportResult> ExportBatchCoreAsync(
                 var json = _formatter.FormatMany(activities, resource);
                 using var content = new StringContent(json, Encoding.UTF8, "application/json");
 
-                var ppapiDiscovery = new PowerPlatformApiDiscovery(options.ClusterCategory);
-                var ppapiEndpoint = ppapiDiscovery.GetTenantIslandClusterEndpoint(tenantId);
-
-                var endpointPath = BuildEndpointPath(agentId, options.UseS2SEndpoint);
-                var requestUri = BuildRequestUri(ppapiEndpoint, endpointPath);
+                string endpointPath = this.BuildEndpointPath(agentId: agentId, useS2SEndpoint: options.UseS2SEndpoint);
+                var endpoint = EnvironmentUtils.IsCustomDomainEnabled()
+                    ? new Agent365EndpointDiscovery(options.ClusterCategory).GetHost()
+                    : new PowerPlatformApiDiscovery(options.ClusterCategory).GetTenantIslandClusterEndpoint(tenantId);
+                var requestUri = Agent365ExporterCore.BuildRequestUri(endpoint, endpointPath);
 
                 using var request = new HttpRequestMessage(HttpMethod.Post, requestUri)
                 {
@@ -149,6 +153,11 @@ public async Task<ExportResult> ExportBatchCoreAsync(
                 if (!string.IsNullOrEmpty(token))
                     request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
 
+                if (EnvironmentUtils.IsCustomDomainEnabled() && !string.IsNullOrEmpty(tenantId))
+                {
+                    request.Headers.TryAddWithoutValidation(Agent365ExporterCore.TenantIdHeaderKey, tenantId);
+                }
+
                 HttpResponseMessage? resp = null;
                 try
                 {
diff --git a/src/Observability/Runtime/Tracing/Exporters/ObservabilityTracerProviderBuilderExtensions.cs b/src/Observability/Runtime/Tracing/Exporters/ObservabilityTracerProviderBuilderExtensions.cs
index ce981d1a..e8cbf23a 100644
--- a/src/Observability/Runtime/Tracing/Exporters/ObservabilityTracerProviderBuilderExtensions.cs
+++ b/src/Observability/Runtime/Tracing/Exporters/ObservabilityTracerProviderBuilderExtensions.cs
@@ -77,9 +77,11 @@ private static TracerProviderBuilder ConfigureInternal(IServiceProvider serviceP
             var coreLogger = serviceProvider.GetService<ILogger<Agent365ExporterCore>>() ?? loggerFactory.CreateLogger<Agent365ExporterCore>();
             var formatterLogger = serviceProvider.GetService<ILogger<ExportFormatter>>() ?? loggerFactory.CreateLogger<ExportFormatter>();
 
+            var configuration = serviceProvider.GetService<Microsoft.Extensions.Configuration.IConfiguration>();
+
             // Create ExportFormatter and Agent365ExporterCore
-            var exportFormatter = new ExportFormatter(formatterLogger);
-            var exporterCore = new Agent365ExporterCore(exportFormatter, coreLogger);
+            var exportFormatter = new ExportFormatter(logger: formatterLogger);
+            var exporterCore = new Agent365ExporterCore(formatter: exportFormatter, logger: coreLogger);
 
             switch (exporterType)
             {
diff --git a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Common/Agent365EndpointDiscoveryTest.cs b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Common/Agent365EndpointDiscoveryTest.cs
new file mode 100644
index 00000000..9400c7a2
--- /dev/null
+++ b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Common/Agent365EndpointDiscoveryTest.cs
@@ -0,0 +1,46 @@
+// ------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// ------------------------------------------------------------------------------
+
+using Microsoft.Agents.A365.Observability.Runtime.Common;
+
+namespace Microsoft.Agents.A365.Observability.Runtime.Tests.Common;
+
+
+[TestClass]
+public class Agent365EndpointDiscoveryTests
+{
+    [TestMethod]
+    public void GetHost_Mapping_IsCorrect()
+    {
+        var expected = new Dictionary<string, string>
+        {
+            ["firstrelease"] = "agent365.svc.cloud.microsoft",
+            ["production"] = "agent365.svc.cloud.microsoft",
+            ["prod"] = "agent365.svc.cloud.microsoft",
+        };
+
+        foreach (var kv in expected)
+        {
+            var disc = new Agent365EndpointDiscovery(kv.Key);
+            Assert.AreEqual(kv.Value, disc.GetHost());
+        }
+    }
+
+    [TestMethod]
+    public void GetHost_IsCaseInsensitive()
+    {
+        var disc1 = new Agent365EndpointDiscovery("PRODUCTION");
+        Assert.AreEqual("agent365.svc.cloud.microsoft", disc1.GetHost());
+
+        var disc2 = new Agent365EndpointDiscovery("PROD");
+        Assert.AreEqual("agent365.svc.cloud.microsoft", disc2.GetHost());
+    }
+
+    [TestMethod]
+    public void GetHost_ThrowsForUnknown()
+    {
+        var disc = new Agent365EndpointDiscovery("unknown-category");
+        Assert.ThrowsException<System.ArgumentException>(() => disc.GetHost());
+    }
+}
diff --git a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Common/EnvironmentUtilsTests.cs b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Common/EnvironmentUtilsTests.cs
new file mode 100644
index 00000000..88ef839f
--- /dev/null
+++ b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Common/EnvironmentUtilsTests.cs
@@ -0,0 +1,126 @@
+// ------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// ------------------------------------------------------------------------------
+
+using FluentAssertions;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Agents.A365.Observability.Runtime.Common;
+
+namespace Microsoft.Agents.A365.Observability.Runtime.Tests.Common
+{
+    [TestClass]
+    public class EnvironmentUtilsTests
+    {
+        private static IConfiguration BuildConfig(IDictionary<string, string?>? values = null)
+        {
+            var builder = new ConfigurationBuilder();
+            if (values != null)
+            {
+                builder.AddInMemoryCollection(values);
+            }
+            return builder.Build();
+        }
+
+        [TestMethod]
+        public void GetObservabilityAuthenticationScope_UsesAgent365Scope_WhenCustomDomainEnabled()
+        {
+            // Arrange
+            var configEnabled = BuildConfig(new Dictionary<string, string?>
+            {
+                { "EnableAgent365CustomDomain", "true" }
+            });
+
+            EnvironmentUtils.Initialize(configuration: configEnabled, force: true);
+
+            // Act
+            var scope = EnvironmentUtils.GetObservabilityAuthenticationScope();
+
+            // Assert
+            scope.Should().ContainSingle().Which.Should().Be("api://9b975845-388f-4429-889e-eab1ef63949c/.default");
+        }
+
+        [TestMethod]
+        public void GetObservabilityAuthenticationScope_UsesProdScope_WhenCustomDomainDisabled()
+        {
+            // Arrange
+            var configDisabled = BuildConfig(new Dictionary<string, string?>
+            {
+                { "EnableAgent365CustomDomain", "false" }
+            });
+
+            EnvironmentUtils.Initialize(configuration: configDisabled, force: true);
+
+            // Act
+            var scope = EnvironmentUtils.GetObservabilityAuthenticationScope();
+
+            // Assert
+            scope.Should().ContainSingle().Which.Should().Be("https://api.powerplatform.com/.default");
+        }
+
+        [TestMethod]
+        public void GetObservabilityAuthenticationScope_UsesProdScope_WhenCustomDomainSettingMissing()
+        {
+            // Arrange
+            var configMissing = BuildConfig();
+
+            EnvironmentUtils.Initialize(configuration: configMissing, force: true);
+
+            // Act
+            var scope = EnvironmentUtils.GetObservabilityAuthenticationScope();
+
+            // Assert
+            scope.Should().ContainSingle().Which.Should().Be("https://api.powerplatform.com/.default");
+        }
+
+        [TestMethod]
+        public void IsCustomDomainEnabled_ReturnsTrue_WhenConfigValueTrue()
+        {
+            // Arrange
+            var config = BuildConfig(new Dictionary<string, string?>
+            {
+                { "EnableAgent365CustomDomain", "true" }
+            });
+
+            EnvironmentUtils.Initialize(configuration: config, force: true);
+
+            // Act
+            var result = EnvironmentUtils.IsCustomDomainEnabled();
+
+            // Assert
+            result.Should().BeTrue();
+        }
+
+        [TestMethod]
+        public void IsCustomDomainEnabled_ReturnsFalse_WhenConfigValueFalse()
+        {
+            // Arrange
+            var config = BuildConfig(new Dictionary<string, string?>
+            {
+                { "EnableAgent365CustomDomain", "false" }
+            });
+
+            EnvironmentUtils.Initialize(configuration: config, force: true);
+
+            // Act
+            var result = EnvironmentUtils.IsCustomDomainEnabled();
+
+            // Assert
+            result.Should().BeFalse();
+        }
+
+        [TestMethod]
+        public void IsCustomDomainEnabled_ReturnsFalse_WhenConfigValueMissing()
+        {
+            // Arrange
+            var config = BuildConfig();
+
+            EnvironmentUtils.Initialize(configuration: config, force: true);
+
+            // Act
+            var result = EnvironmentUtils.IsCustomDomainEnabled();
+
+            // Assert
+            result.Should().BeFalse();
+        }
+    }
+}
diff --git a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Exporters/Agent365ExporterTests.cs b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Exporters/Agent365ExporterTests.cs
index 7eaf1a5d..96ddf829 100644
--- a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Exporters/Agent365ExporterTests.cs
+++ b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Exporters/Agent365ExporterTests.cs
@@ -1,4 +1,4 @@
-using FluentAssertions;
+using FluentAssertions;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Agents.A365.Observability.Runtime.Common;
 using Microsoft.Agents.A365.Observability.Runtime.Tracing.Exporters;
@@ -7,6 +7,7 @@
 using OpenTelemetry.Resources;
 using System.Diagnostics;
 using System.Reflection;
+using Microsoft.Extensions.Configuration;
 
 namespace Microsoft.Agents.A365.Observability.Tests.Tracing.Exporters;
 
@@ -112,7 +113,17 @@ private static Agent365Exporter CreateExporter(Func<string, string, string?>? to
             resource);
     }
 
-    [TestMethod]
+    private static void SetCustomDomain(bool enabled)
+    {
+        var _configuration = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                { "EnableAgent365CustomDomain", enabled ? bool.TrueString : bool.FalseString }
+            })
+            .Build();
+        EnvironmentUtils.Initialize(configuration: _configuration, force: true);
+    }
+
     public void Constructor_NullLogger_Throws()
     {
         var options = new Agent365ExporterOptions
@@ -1014,4 +1025,145 @@ public void Export_StandardEndpoint_WithDifferentClusterCategories_ProcessesCorr
     }
 
     #endregion
+
+    #region Build Endpoint and URI Tests
+    [TestMethod]
+    public void BuildEndpointPath_CustomDomain_UsesAgentsRoot()
+    {
+        Agent365ExporterTests.SetCustomDomain(true);
+        var path = Agent365ExporterTests._agent365ExporterCore.BuildEndpointPath("agent-123", useS2SEndpoint: true);
+        path.Should().Be("/agents/agent-123/traces");
+    }
+
+    [TestMethod]
+    public void BuildEndpointPath_NonCustomDomain_UsesServicePathsDependingOnS2S()
+    {
+        Agent365ExporterTests.SetCustomDomain(false);
+        var s2s = Agent365ExporterTests._agent365ExporterCore.BuildEndpointPath("agent-123", useS2SEndpoint: true);
+        var standard = Agent365ExporterTests._agent365ExporterCore.BuildEndpointPath("agent-123", useS2SEndpoint: false);
+        s2s.Should().Be("/maven/agent365/service/agents/agent-123/traces");
+        standard.Should().Be("/maven/agent365/agents/agent-123/traces");
+    }
+
+    [TestMethod]
+    public void BuildRequestUri_ComposesCorrectly()
+    {
+        var uri = Agent365ExporterCore.BuildRequestUri("example.com", "/agents/agent-123/traces");
+        uri.Should().Be("https://example.com/agents/agent-123/traces?api-version=1");
+    }
+    #endregion
+
+    #region ExportBatchCoreAsync Request Uri and Headers Tests
+    [TestMethod]
+    public async Task ExportBatchCoreAsync_CustomDomain_UsesBaseHostAndAddsTenantHeader()
+    {
+        // Arrange
+        Agent365ExporterTests.SetCustomDomain(true);
+        var tenantId = "tenant-xyz";
+        var agentId = "agent-abc";
+        var resource = ResourceBuilder.CreateEmpty().AddService("unit-test-service", serviceVersion: "1.0.0").Build();
+        var options = new Agent365ExporterOptions
+        {
+            TokenResolver = (_, _) => Task.FromResult<string?>(null),
+            UseS2SEndpoint = true,
+            ClusterCategory = "prod"
+        };
+
+        // Create a fake activity with identity
+        using var activity = CreateActivity(tenantId: tenantId, agentId: agentId);
+        var groups = new List<(string TenantId, string AgentId, List<Activity> Activities)>
+        {
+            (tenantId, agentId, new List<Activity> { activity })
+        };
+
+        // Capture request details
+        string? capturedHost = null;
+        string? capturedPathAndQuery = null;
+        string? capturedTenantHeader = null;
+
+        var expectedHost = new Agent365EndpointDiscovery(options.ClusterCategory).GetHost();
+
+        Task<HttpResponseMessage> sendAsync(HttpRequestMessage req)
+        {
+            capturedHost = req.RequestUri!.Host;
+            capturedPathAndQuery = req.RequestUri!.PathAndQuery;
+            req.Headers.TryGetValues("x-ms-tenant-id", out var vals);
+            capturedTenantHeader = vals?.FirstOrDefault();
+            var response = new HttpResponseMessage(System.Net.HttpStatusCode.InternalServerError);
+            response.Headers.Add("x-ms-correlation-id", Guid.NewGuid().ToString());
+            return Task.FromResult(response);
+        }
+
+        // Act
+        var result = await Agent365ExporterTests._agent365ExporterCore.ExportBatchCoreAsync(
+            groups,
+            resource,
+            options,
+            (a, t) => Task.FromResult<string?>(null),
+            sendAsync);
+
+        // Assert
+        result.Should().Be(ExportResult.Failure); // Expected to fail due to no real endpoint
+        capturedHost.Should().Be(expectedHost);
+        capturedPathAndQuery.Should().StartWith("/agents/" + agentId + "/traces");
+        capturedPathAndQuery.Should().EndWith("?api-version=1");
+        capturedTenantHeader.Should().Be(tenantId);
+    }
+
+    [TestMethod]
+    public async Task ExportBatchCoreAsync_NonCustomDomain_UsesPowerPlatformEndpoint()
+    {
+        // Arrange
+        Agent365ExporterTests.SetCustomDomain(false);
+        var tenantId = "tenant-xyz";
+        var agentId = "agent-abc";
+        var resource = ResourceBuilder.CreateEmpty().AddService("unit-test-service", serviceVersion: "1.0.0").Build();
+        var options = new Agent365ExporterOptions
+        {
+            TokenResolver = (_, _) => Task.FromResult<string?>(null),
+            UseS2SEndpoint = true,
+            ClusterCategory = "prod"
+        };
+
+        using var activity = CreateActivity(tenantId: tenantId, agentId: agentId);
+        var groups = new List<(string TenantId, string AgentId, List<Activity> Activities)>
+        {
+            (tenantId, agentId, new List<Activity> { activity })
+        };
+
+        string? capturedHost = null;
+        string? capturedPathAndQuery = null;
+        string? capturedTenantHeader = null;
+
+        var expectedHost = new PowerPlatformApiDiscovery(options.ClusterCategory).GetTenantIslandClusterEndpoint(tenantId);
+
+        Task<HttpResponseMessage> sendAsync(HttpRequestMessage req)
+        {
+            capturedHost = req.RequestUri!.Host;
+            capturedPathAndQuery = req.RequestUri!.PathAndQuery;
+            if (req.Headers.TryGetValues("x-ms-tenant-id", out var vals))
+            {
+                capturedTenantHeader = vals.FirstOrDefault();
+            }
+            var response = new HttpResponseMessage(System.Net.HttpStatusCode.InternalServerError);
+            response.Headers.Add("x-ms-correlation-id", Guid.NewGuid().ToString());
+            return Task.FromResult(response);
+        }
+
+        // Act
+        var result = await Agent365ExporterTests._agent365ExporterCore.ExportBatchCoreAsync(
+            groups,
+            resource,
+            options,
+            (a, t) => Task.FromResult<string?>(null),
+            sendAsync);
+
+        // Assert
+        result.Should().Be(ExportResult.Failure); // Expected to fail due to no real endpoint
+        capturedHost.Should().Be(expectedHost);
+        capturedPathAndQuery.Should().StartWith("/maven/agent365/service/agents/" + agentId + "/traces");
+        capturedPathAndQuery.Should().EndWith("?api-version=1");
+        capturedTenantHeader.Should().BeNull();
+    }
+    #endregion
 }
\ No newline at end of file