diff --git a/Directory.Packages.props b/Directory.Packages.props
index 1588ffe3..ed8932f6 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -23,6 +23,7 @@
     <PackageVersion Include="Azure.Identity" Version="1.21.0" />
     <PackageVersion Include="Azure.Monitor.OpenTelemetry.AspNetCore" Version="1.5.0" />
     <PackageVersion Include="TUnit" Version="1.40.5" />
+    <PackageVersion Include="TUnit.AspNetCore" Version="1.40.5" />
     <PackageVersion Include="EssentialCSharp.Shared.Models" Version="$(ToolingPackagesVersion)" />
     <PackageVersion Include="HtmlAgilityPack" Version="1.12.4" />
     <PackageVersion Include="IntelliTect.Multitool" Version="2.1.0" />
diff --git a/EssentialCSharp.Web.Tests/ContentRateLimitingTests.cs b/EssentialCSharp.Web.Tests/ContentRateLimitingTests.cs
index cdbb0de4..7685eeca 100644
--- a/EssentialCSharp.Web.Tests/ContentRateLimitingTests.cs
+++ b/EssentialCSharp.Web.Tests/ContentRateLimitingTests.cs
@@ -1,24 +1,18 @@
 using System.Net;
-using Microsoft.AspNetCore.Mvc.Testing;
 
 namespace EssentialCSharp.Web.Tests;
 
 /// <summary>
 /// HTTP integration tests for the "content" rate limit policy.
-/// Uses its own factory (PerClass) to get a fresh in-memory rate limiter for each run.
+/// Each test gets its own factory (fresh IHost) so the rate limiter starts from a clean state.
 /// Anonymous users are limited to 10 requests per minute on chapter content pages.
 /// </summary>
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class ContentRateLimitingTests(WebApplicationFactory factory)
+public class ContentRateLimitingTests : IntegrationTestBase
 {
     [Test]
     public async Task ContentEndpoint_ExceedingPerMinuteLimit_Returns429()
     {
-        // AllowAutoRedirect = false prevents redirect-following from consuming extra permits.
-        HttpClient client = factory.CreateClient(new WebApplicationFactoryClientOptions
-        {
-            AllowAutoRedirect = false
-        });
+        HttpClient client = Factory.CreateClient();
 
         // Anonymous limit is 10/min. First 10 requests should not be rate-limited.
         for (int i = 0; i < 10; i++)
diff --git a/EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj b/EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj
index 3d3fb91e..23a0c5ff 100644
--- a/EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj
+++ b/EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj
@@ -13,6 +13,7 @@
     <PackageReference Include="Moq" />
     <PackageReference Include="Moq.AutoMock" />
     <PackageReference Include="TUnit" />
+    <PackageReference Include="TUnit.AspNetCore" />
     <PackageReference Include="Newtonsoft.Json" />
   </ItemGroup>
 
diff --git a/EssentialCSharp.Web.Tests/FunctionalTests.cs b/EssentialCSharp.Web.Tests/FunctionalTests.cs
index 31aa723e..d3fca5d8 100644
--- a/EssentialCSharp.Web.Tests/FunctionalTests.cs
+++ b/EssentialCSharp.Web.Tests/FunctionalTests.cs
@@ -2,9 +2,7 @@
 
 namespace EssentialCSharp.Web.Tests;
 
-[NotInParallel("FunctionalTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class FunctionalTests(WebApplicationFactory factory)
+public class FunctionalTests : IntegrationTestBase
 {
     [Test]
     [Arguments("/")]
@@ -15,7 +13,7 @@ public class FunctionalTests(WebApplicationFactory factory)
     [Arguments("/alive")]
     public async Task WhenTheApplicationStarts_ItCanLoadLoadPages(string relativeUrl)
     {
-        HttpClient client = factory.CreateClient();
+        HttpClient client = CreateRedirectFollowingClient();
         using HttpResponseMessage response = await client.GetAsync(relativeUrl);
 
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.OK);
@@ -31,7 +29,7 @@ public async Task WhenTheApplicationStarts_ItCanLoadLoadPages(string relativeUrl
     [Arguments("/about?someOtherParam=value")]
     public async Task WhenPagesAreAccessed_TheyReturnHtml(string relativeUrl)
     {
-        HttpClient client = factory.CreateClient();
+        HttpClient client = CreateRedirectFollowingClient();
         using HttpResponseMessage response = await client.GetAsync(relativeUrl);
 
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.OK);
@@ -47,9 +45,9 @@ public async Task WhenPagesAreAccessed_TheyReturnHtml(string relativeUrl)
     [Test]
     public async Task WhenTheApplicationStarts_NonExistingPage_GivesCorrectStatusCode()
     {
-        HttpClient client = factory.CreateClient();
+        HttpClient client = CreateRedirectFollowingClient();
         using HttpResponseMessage response = await client.GetAsync("/non-existing-page1234");
 
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.NotFound);
     }
-}
\ No newline at end of file
+}
diff --git a/EssentialCSharp.Web.Tests/IntegrationTestBase.cs b/EssentialCSharp.Web.Tests/IntegrationTestBase.cs
new file mode 100644
index 00000000..a7bf21b0
--- /dev/null
+++ b/EssentialCSharp.Web.Tests/IntegrationTestBase.cs
@@ -0,0 +1,42 @@
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.DependencyInjection;
+using TUnit.AspNetCore;
+
+namespace EssentialCSharp.Web.Tests;
+
+public abstract class IntegrationTestBase : WebApplicationTest<WebApplicationFactory, Program>
+{
+    /// <summary>
+    /// Creates an HTTP client with redirect following enabled.
+    /// NOTE: This bypasses TUnit trace correlation because <see cref="TracedWebApplicationFactory{T}"/>
+    /// does not expose a <c>CreateClient(WebApplicationFactoryClientOptions)</c> overload.
+    /// Use <see cref="TUnit.AspNetCore.TracedWebApplicationFactory{T}.CreateClient()"/> for all
+    /// other tests where AllowAutoRedirect=false is acceptable.
+    /// </summary>
+    protected HttpClient CreateRedirectFollowingClient() =>
+        Factory.Inner.CreateClient(new WebApplicationFactoryClientOptions { AllowAutoRedirect = true });
+
+    public T InServiceScope<T>(Func<IServiceProvider, T> action)
+    {
+        using IServiceScope scope = Factory.Services.GetRequiredService<IServiceScopeFactory>().CreateScope();
+        return action(scope.ServiceProvider);
+    }
+
+    public void InServiceScope(Action<IServiceProvider> action)
+    {
+        using IServiceScope scope = Factory.Services.GetRequiredService<IServiceScopeFactory>().CreateScope();
+        action(scope.ServiceProvider);
+    }
+
+    public async Task<T> InServiceScopeAsync<T>(Func<IServiceProvider, Task<T>> action)
+    {
+        using IServiceScope scope = Factory.Services.GetRequiredService<IServiceScopeFactory>().CreateScope();
+        return await action(scope.ServiceProvider);
+    }
+
+    public async Task InServiceScopeAsync(Func<IServiceProvider, Task> action)
+    {
+        using IServiceScope scope = Factory.Services.GetRequiredService<IServiceScopeFactory>().CreateScope();
+        await action(scope.ServiceProvider);
+    }
+}
diff --git a/EssentialCSharp.Web.Tests/ListingSourceCodeControllerTests.cs b/EssentialCSharp.Web.Tests/ListingSourceCodeControllerTests.cs
index 05a29baa..7232a7c3 100644
--- a/EssentialCSharp.Web.Tests/ListingSourceCodeControllerTests.cs
+++ b/EssentialCSharp.Web.Tests/ListingSourceCodeControllerTests.cs
@@ -4,14 +4,13 @@
 
 namespace EssentialCSharp.Web.Tests;
 
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class ListingSourceCodeControllerTests(WebApplicationFactory factory)
+public class ListingSourceCodeControllerTests : IntegrationTestBase
 {
     [Test]
     public async Task GetListing_WithValidChapterAndListing_Returns200WithContent()
     {
         // Arrange
-        HttpClient client = factory.CreateClient();
+        HttpClient client = Factory.CreateClient();
 
         // Act
         using HttpResponseMessage response = await client.GetAsync("/api/ListingSourceCode/chapter/1/listing/1");
@@ -35,7 +34,7 @@ public async Task GetListing_WithValidChapterAndListing_Returns200WithContent()
     public async Task GetListing_WithInvalidChapter_Returns404()
     {
         // Arrange
-        HttpClient client = factory.CreateClient();
+        HttpClient client = Factory.CreateClient();
 
         // Act
         using HttpResponseMessage response = await client.GetAsync("/api/ListingSourceCode/chapter/999/listing/1");
@@ -48,7 +47,7 @@ public async Task GetListing_WithInvalidChapter_Returns404()
     public async Task GetListing_WithInvalidListing_Returns404()
     {
         // Arrange
-        HttpClient client = factory.CreateClient();
+        HttpClient client = Factory.CreateClient();
 
         // Act
         using HttpResponseMessage response = await client.GetAsync("/api/ListingSourceCode/chapter/1/listing/999");
@@ -61,7 +60,7 @@ public async Task GetListing_WithInvalidListing_Returns404()
     public async Task GetListingsByChapter_WithValidChapter_ReturnsMultipleListings()
     {
         // Arrange
-        HttpClient client = factory.CreateClient();
+        HttpClient client = Factory.CreateClient();
 
         // Act
         using HttpResponseMessage response = await client.GetAsync("/api/ListingSourceCode/chapter/1");
@@ -92,7 +91,7 @@ public async Task GetListingsByChapter_WithValidChapter_ReturnsMultipleListings(
     public async Task GetListingsByChapter_WithInvalidChapter_ReturnsEmptyList()
     {
         // Arrange
-        HttpClient client = factory.CreateClient();
+        HttpClient client = Factory.CreateClient();
 
         // Act
         using HttpResponseMessage response = await client.GetAsync("/api/ListingSourceCode/chapter/999");
diff --git a/EssentialCSharp.Web.Tests/McpApiTokenServiceTests.cs b/EssentialCSharp.Web.Tests/McpApiTokenServiceTests.cs
index 8e78d718..0eb417bd 100644
--- a/EssentialCSharp.Web.Tests/McpApiTokenServiceTests.cs
+++ b/EssentialCSharp.Web.Tests/McpApiTokenServiceTests.cs
@@ -1,13 +1,10 @@
 using EssentialCSharp.Web.Models;
 using EssentialCSharp.Web.Services;
-using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace EssentialCSharp.Web.Tests;
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpApiTokenServiceTests(WebApplicationFactory factory)
+public class McpApiTokenServiceTests : IntegrationTestBase
 {
     private readonly List<IServiceScope> _scopes = [];
 
@@ -21,8 +18,8 @@ public void DisposeScopes()
 
     private async Task<(string UserId, McpApiTokenService TokenService)> ArrangeAsync(string prefix)
     {
-        string userId = await McpTestHelper.CreateUserAsync(factory, prefix);
-        var scope = factory.Services.CreateScope();
+        string userId = await McpTestHelper.CreateUserAsync(Factory, prefix);
+        var scope = Factory.Services.CreateScope();
         _scopes.Add(scope);
         var tokenService = scope.ServiceProvider.GetRequiredService<McpApiTokenService>();
         return (userId, tokenService);
@@ -30,7 +27,7 @@ public void DisposeScopes()
 
     private async Task<McpApiTokenService> FillToLimitAsync(string userId)
     {
-        var scope = factory.Services.CreateScope();
+        var scope = Factory.Services.CreateScope();
         _scopes.Add(scope);
         var tokenService = scope.ServiceProvider.GetRequiredService<McpApiTokenService>();
         for (int i = 0; i < McpApiTokenService.MaxTokensPerUser; i++)
diff --git a/EssentialCSharp.Web.Tests/McpRateLimitingTests.cs b/EssentialCSharp.Web.Tests/McpRateLimitingTests.cs
index a89be156..202f0a56 100644
--- a/EssentialCSharp.Web.Tests/McpRateLimitingTests.cs
+++ b/EssentialCSharp.Web.Tests/McpRateLimitingTests.cs
@@ -2,27 +2,25 @@
 using System.Text.Json;
 using EssentialCSharp.Web.Data;
 using EssentialCSharp.Web.Services;
-using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace EssentialCSharp.Web.Tests;
 
 /// <summary>
-/// Each class gets its own factory so the global limiter starts from a fresh state.
+/// Each test method gets its own per-test factory (fresh IHost + rate limiter state)
+/// via TUnit.AspNetCore's WebApplicationTest, so [NotInParallel] is no longer needed.
 /// </summary>
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpDistinctUserRateLimitingTests(WebApplicationFactory factory)
+public class McpRateLimitingTests : IntegrationTestBase
 {
     [Test]
     public async Task DistinctValidMcpUsers_DoNotShareRateLimitBucket()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         for (int i = 0; i < 31; i++)
         {
             (_, string rawToken) = await McpTestHelper.CreateUserAndTokenAsync(
-                factory,
+                Factory,
                 $"mcp-rate-limit-isolation-{i}",
                 userPrefix: $"mcp-isolation-{i}");
 
@@ -35,20 +33,15 @@ await Assert.That(response.StatusCode)
                 .Because($"distinct MCP user request {i + 1} should use its own rate-limit bucket");
         }
     }
-}
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpPerUserRateLimitingTests(WebApplicationFactory factory)
-{
     [Test]
     public async Task SingleValidMcpUser_ExceedingTokenBucket_Returns429AndDoesNotCountRejectedRequests()
     {
         (_, string rawToken) = await McpTestHelper.CreateUserAndTokenAsync(
-            factory,
+            Factory,
             "mcp-rate-limit-single-user",
             userPrefix: "mcp-single-user");
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         List<HttpStatusCode> statuses = [];
         string? rateLimitedPayload = null;
         string? rateLimitedContentType = null;
@@ -70,7 +63,7 @@ public async Task SingleValidMcpUser_ExceedingTokenBucket_Returns429AndDoesNotCo
             }
         }
 
-        (long UsageCount, bool HasLastUsedAt) tokenUsage = factory.InServiceScope(services =>
+        (long UsageCount, bool HasLastUsedAt) tokenUsage = InServiceScope(services =>
         {
             var db = services.GetRequiredService<EssentialCSharpWebContext>();
             byte[] tokenHash = McpApiTokenService.HashToken(rawToken);
@@ -104,16 +97,11 @@ await Assert.That(statuses.Skip(McpRateLimiterPolicy.AuthenticatedTokenLimit)
         await Assert.That(error.GetProperty("code").GetInt32()).IsEqualTo(-32000);
         await Assert.That(error.GetProperty("message").GetString()).Contains("Rate limit exceeded");
     }
-}
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpAnonymousRateLimitingTests(WebApplicationFactory factory)
-{
     [Test]
     public async Task InvalidMcpBearerRequests_FallBackToAnonymousIpBucket()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         for (int i = 0; i < McpRateLimiterPolicy.AnonymousPermitLimit; i++)
         {
@@ -132,21 +120,16 @@ await Assert.That(response.StatusCode)
         using HttpResponseMessage rateLimitedResponse = await client.SendAsync(rateLimitedRequest);
         await Assert.That(rateLimitedResponse.StatusCode).IsEqualTo(HttpStatusCode.TooManyRequests);
     }
-}
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpCookieIsolationRateLimitingTests(WebApplicationFactory factory)
-{
     [Test]
     public async Task InvalidMcpBearerRequests_WithDifferentSiteCookies_StillShareAnonymousIpBucket()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         for (int i = 0; i < McpRateLimiterPolicy.AnonymousPermitLimit; i++)
         {
-            string cookieUserId = await McpTestHelper.CreateUserAsync(factory, $"mcp-cookie-user-{i}");
-            (string cookieName, string cookieValue) = await McpTestHelper.CreateIdentityApplicationCookieAsync(factory, cookieUserId);
+            string cookieUserId = await McpTestHelper.CreateUserAsync(Factory, $"mcp-cookie-user-{i}");
+            (string cookieName, string cookieValue) = await McpTestHelper.CreateIdentityApplicationCookieAsync(Factory, cookieUserId);
 
             using var request = McpTestHelper.CreateInitializeRequest("/mcp");
             McpTestHelper.AddBearerToken(request, "mcp_invalid_token_that_does_not_exist");
@@ -158,8 +141,8 @@ await Assert.That(response.StatusCode)
                 .Because($"invalid MCP bearer request {i + 1} should ignore the site cookie principal and stay in the anonymous/IP bucket");
         }
 
-        string finalCookieUserId = await McpTestHelper.CreateUserAsync(factory, "mcp-cookie-user-final");
-        (string finalCookieName, string finalCookieValue) = await McpTestHelper.CreateIdentityApplicationCookieAsync(factory, finalCookieUserId);
+        string finalCookieUserId = await McpTestHelper.CreateUserAsync(Factory, "mcp-cookie-user-final");
+        (string finalCookieName, string finalCookieValue) = await McpTestHelper.CreateIdentityApplicationCookieAsync(Factory, finalCookieUserId);
 
         using var rateLimitedRequest = McpTestHelper.CreateInitializeRequest("/mcp");
         McpTestHelper.AddBearerToken(rateLimitedRequest, "mcp_invalid_token_that_does_not_exist");
@@ -168,20 +151,15 @@ await Assert.That(response.StatusCode)
         using HttpResponseMessage rateLimitedResponse = await client.SendAsync(rateLimitedRequest);
         await Assert.That(rateLimitedResponse.StatusCode).IsEqualTo(HttpStatusCode.TooManyRequests);
     }
-}
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpGlobalBypassRateLimitingTests(WebApplicationFactory factory)
-{
     [Test]
     public async Task ValidMcpPostRequests_DoNotConsumeGlobalLimiterBudgetForGetShim()
     {
         (_, string rawToken) = await McpTestHelper.CreateUserAndTokenAsync(
-            factory,
+            Factory,
             "mcp-global-bypass",
             userPrefix: "mcp-bypass");
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         for (int i = 0; i < 10; i++)
         {
@@ -211,16 +189,11 @@ await Assert.That(getResponse.StatusCode)
         using HttpResponseMessage rateLimitedGetResponse = await client.SendAsync(rateLimitedGetRequest);
         await Assert.That(rateLimitedGetResponse.StatusCode).IsEqualTo(HttpStatusCode.TooManyRequests);
     }
-}
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpWellKnownIsolationRateLimitingTests(WebApplicationFactory factory)
-{
     [Test]
     public async Task WellKnownRequests_DoNotConsumeContentLimiterBudget()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         for (int i = 0; i < 10; i++)
         {
@@ -243,3 +216,4 @@ await Assert.That(contentResponse.StatusCode)
         await Assert.That(rateLimitedResponse.StatusCode).IsEqualTo(HttpStatusCode.TooManyRequests);
     }
 }
+
diff --git a/EssentialCSharp.Web.Tests/McpTestHelper.cs b/EssentialCSharp.Web.Tests/McpTestHelper.cs
index 12ed4255..db610ea4 100644
--- a/EssentialCSharp.Web.Tests/McpTestHelper.cs
+++ b/EssentialCSharp.Web.Tests/McpTestHelper.cs
@@ -6,18 +6,16 @@
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Authentication.Cookies;
 using Microsoft.AspNetCore.Identity;
-using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
+using TUnit.AspNetCore;
 
 namespace EssentialCSharp.Web.Tests;
 
 internal static class McpTestHelper
 {
-    public static HttpClient CreateClient(WebApplicationFactory factory) => factory.CreateClient(new WebApplicationFactoryClientOptions
-    {
-        AllowAutoRedirect = false
-    });
+    public static HttpClient CreateClient(TracedWebApplicationFactory<Program> factory) =>
+        factory.CreateClient();
 
     public static HttpRequestMessage CreateInitializeRequest(string path = "/mcp")
     {
@@ -50,7 +48,7 @@ public static void AddBearerToken(HttpRequestMessage request, string rawToken) =
     public static void AddCookie(HttpRequestMessage request, string cookieName, string cookieValue) =>
         request.Headers.Add("Cookie", $"{cookieName}={cookieValue}");
 
-    public static async Task<string> CreateUserAsync(WebApplicationFactory factory, string userPrefix)
+    public static async Task<string> CreateUserAsync(TracedWebApplicationFactory<Program> factory, string userPrefix)
     {
         string userId = Guid.NewGuid().ToString();
         string suffix = Guid.NewGuid().ToString("N")[..8];
@@ -73,7 +71,7 @@ public static async Task<string> CreateUserAsync(WebApplicationFactory factory,
     }
 
     public static async Task<(string UserId, string RawToken)> CreateUserAndTokenAsync(
-        WebApplicationFactory factory,
+        TracedWebApplicationFactory<Program> factory,
         string tokenName,
         string userPrefix = "mcp-test",
         DateTime? expiresAt = null)
@@ -90,7 +88,7 @@ public static async Task<string> CreateUserAsync(WebApplicationFactory factory,
     }
 
     public static async Task<(string CookieName, string CookieValue)> CreateIdentityApplicationCookieAsync(
-        WebApplicationFactory factory,
+        TracedWebApplicationFactory<Program> factory,
         string userId)
     {
         using var scope = factory.Services.CreateScope();
diff --git a/EssentialCSharp.Web.Tests/McpTests.cs b/EssentialCSharp.Web.Tests/McpTests.cs
index 109b1f10..a4f4d5ed 100644
--- a/EssentialCSharp.Web.Tests/McpTests.cs
+++ b/EssentialCSharp.Web.Tests/McpTests.cs
@@ -1,19 +1,16 @@
 using System.Net;
 using System.Text;
 using EssentialCSharp.Web.Services;
-using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace EssentialCSharp.Web.Tests;
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpTests(WebApplicationFactory factory)
+public class McpTests : IntegrationTestBase
 {
     [Test]
     public async Task McpTokenEndpoint_WithoutAuth_Returns401()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         using HttpResponseMessage response = await client.PostAsync("/api/McpToken", null);
 
@@ -23,7 +20,7 @@ public async Task McpTokenEndpoint_WithoutAuth_Returns401()
     [Test]
     public async Task McpEndpoint_WithoutToken_Returns401()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         using var request = McpTestHelper.CreateInitializeRequest("/mcp");
         using HttpResponseMessage response = await client.SendAsync(request);
@@ -34,11 +31,11 @@ public async Task McpEndpoint_WithoutToken_Returns401()
     [Test]
     public async Task McpEndpoint_WithSiteCookieButWithoutBearer_Returns401()
     {
-        string cookieUserId = await McpTestHelper.CreateUserAsync(factory, "mcp-cookie-only");
+        string cookieUserId = await McpTestHelper.CreateUserAsync(Factory, "mcp-cookie-only");
         (string cookieName, string cookieValue) =
-            await McpTestHelper.CreateIdentityApplicationCookieAsync(factory, cookieUserId);
+            await McpTestHelper.CreateIdentityApplicationCookieAsync(Factory, cookieUserId);
 
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         using var request = McpTestHelper.CreateInitializeRequest("/mcp");
         McpTestHelper.AddCookie(request, cookieName, cookieValue);
 
@@ -51,11 +48,11 @@ public async Task McpEndpoint_WithSiteCookieButWithoutBearer_Returns401()
     public async Task McpEndpoint_WithValidToken_Returns200AndListsTools()
     {
         (_, string rawToken) = await McpTestHelper.CreateUserAndTokenAsync(
-            factory,
+            Factory,
             "integration-test",
             userPrefix: "mcp-testuser");
 
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         // Step 1: Initialize the MCP session
         using var initRequest = McpTestHelper.CreateInitializeRequest("/mcp");
@@ -108,7 +105,7 @@ public async Task McpEndpoint_WithValidToken_Returns200AndListsTools()
     [Test]
     public async Task McpEndpoint_WithInvalidToken_Returns401()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         using var request = McpTestHelper.CreateInitializeRequest("/mcp");
         McpTestHelper.AddBearerToken(request, "mcp_invalid_token_that_does_not_exist");
         using HttpResponseMessage response = await client.SendAsync(request);
@@ -118,16 +115,16 @@ public async Task McpEndpoint_WithInvalidToken_Returns401()
     [Test]
     public async Task McpEndpoint_WithRevokedToken_Returns401()
     {
-        string testUserId = await McpTestHelper.CreateUserAsync(factory, "revoked-user");
+        string testUserId = await McpTestHelper.CreateUserAsync(Factory, "revoked-user");
         string rawToken;
-        using (var scope = factory.Services.CreateScope())
+        using (var scope = Factory.Services.CreateScope())
         {
             var tokenService = scope.ServiceProvider.GetRequiredService<McpApiTokenService>();
             (rawToken, var entity) = await tokenService.CreateTokenAsync(testUserId, "revoke-test");
             await tokenService.RevokeTokenAsync(entity.Id, testUserId);
         }
 
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         using var request = McpTestHelper.CreateInitializeRequest("/mcp");
         McpTestHelper.AddBearerToken(request, rawToken);
         using HttpResponseMessage response = await client.SendAsync(request);
@@ -138,12 +135,12 @@ public async Task McpEndpoint_WithRevokedToken_Returns401()
     public async Task McpEndpoint_WithExpiredToken_Returns401()
     {
         (_, string rawToken) = await McpTestHelper.CreateUserAndTokenAsync(
-            factory,
+            Factory,
             "expired-test",
             userPrefix: "expired-user",
             expiresAt: DateTime.UtcNow.AddSeconds(-1));
 
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         using var request = McpTestHelper.CreateInitializeRequest("/mcp");
         McpTestHelper.AddBearerToken(request, rawToken);
         using HttpResponseMessage response = await client.SendAsync(request);
@@ -153,7 +150,7 @@ public async Task McpEndpoint_WithExpiredToken_Returns401()
     [Test]
     public async Task WellKnownOAuthProtectedResource_AllMethodsReturn404WithoutRedirectAndNoStore()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         foreach (HttpMethod method in new[] { HttpMethod.Get, HttpMethod.Post, HttpMethod.Options })
         {
@@ -171,7 +168,7 @@ await Assert.That(response.StatusCode)
     [Test]
     public async Task McpEndpoint_PreflightFromLoopbackOrigin_ReturnsCorsHeaders()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         using var request = new HttpRequestMessage(HttpMethod.Options, "/mcp");
         request.Headers.Add("Origin", "http://localhost:6274");
         request.Headers.Add("Access-Control-Request-Method", "POST");
@@ -191,7 +188,7 @@ public async Task McpEndpoint_PreflightFromLoopbackOrigin_ReturnsCorsHeaders()
     [Test]
     public async Task McpEndpoint_GetFromLoopbackOrigin_Returns405WithoutRedirect()
     {
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
         using var request = new HttpRequestMessage(HttpMethod.Get, "/mcp");
         request.Headers.Add("Origin", "http://localhost:6274");
         request.Headers.Accept.ParseAdd("text/event-stream");
diff --git a/EssentialCSharp.Web.Tests/McpToolContractTests.cs b/EssentialCSharp.Web.Tests/McpToolContractTests.cs
index ec806220..d9e1582f 100644
--- a/EssentialCSharp.Web.Tests/McpToolContractTests.cs
+++ b/EssentialCSharp.Web.Tests/McpToolContractTests.cs
@@ -2,15 +2,12 @@
 using System.Text;
 using System.Text.Json;
 using EssentialCSharp.Web.Services;
-using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 
 namespace EssentialCSharp.Web.Tests;
 
-[NotInParallel("McpTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class McpToolContractTests(WebApplicationFactory factory)
+public class McpToolContractTests : IntegrationTestBase
 {
     [Test]
     public async Task McpToolsList_StructuredAndHybridTools_AdvertiseOutputSchema()
@@ -201,10 +198,10 @@ public async Task McpCall_GetChapterSections_WithInvalidChapter_ReturnsMcpError(
     private async Task<(HttpClient Client, string RawToken, string? SessionId)> CreateAuthenticatedSessionAsync()
     {
         (_, string rawToken) = await McpTestHelper.CreateUserAndTokenAsync(
-            factory,
+            Factory,
             "mcp-contract-test",
             userPrefix: "mcp-contract");
-        HttpClient client = McpTestHelper.CreateClient(factory);
+        HttpClient client = McpTestHelper.CreateClient(Factory);
 
         using var initRequest = McpTestHelper.CreateInitializeRequest("/mcp");
         McpTestHelper.AddBearerToken(initRequest, rawToken);
@@ -223,7 +220,7 @@ public async Task McpCall_GetChapterSections_WithInvalidChapter_ReturnsMcpError(
 
     private string GetConfiguredBaseUrl()
     {
-        string baseUrl = factory.Services.GetRequiredService<IOptions<SiteSettings>>().Value.BaseUrl;
+        string baseUrl = Factory.Services.GetRequiredService<IOptions<SiteSettings>>().Value.BaseUrl;
         return baseUrl.TrimEnd('/') + "/";
     }
 
diff --git a/EssentialCSharp.Web.Tests/RouteConfigurationServiceTests.cs b/EssentialCSharp.Web.Tests/RouteConfigurationServiceTests.cs
index ed5866fc..a238451d 100644
--- a/EssentialCSharp.Web.Tests/RouteConfigurationServiceTests.cs
+++ b/EssentialCSharp.Web.Tests/RouteConfigurationServiceTests.cs
@@ -3,21 +3,13 @@
 
 namespace EssentialCSharp.Web.Tests;
 
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class RouteConfigurationServiceTests
+public class RouteConfigurationServiceTests : IntegrationTestBase
 {
-    private readonly WebApplicationFactory _Factory;
-
-    public RouteConfigurationServiceTests(WebApplicationFactory factory)
-    {
-        _Factory = factory;
-    }
-
     [Test]
     public async Task GetStaticRoutes_ShouldReturnExpectedRoutes()
     {
         // Act
-        var routes = _Factory.InServiceScope(serviceProvider =>
+        var routes = InServiceScope(serviceProvider =>
         {
             var routeConfigurationService = serviceProvider.GetRequiredService<IRouteConfigurationService>();
             return routeConfigurationService.GetStaticRoutes().ToList();
@@ -33,4 +25,4 @@ public async Task GetStaticRoutes_ShouldReturnExpectedRoutes()
         await Assert.That(routes).Contains("announcements");
         await Assert.That(routes).Contains("termsofservice");
     }
-}
\ No newline at end of file
+}
diff --git a/EssentialCSharp.Web.Tests/SitemapXmlHelpersTests.cs b/EssentialCSharp.Web.Tests/SitemapXmlHelpersTests.cs
index 1adc0dff..b47b49bf 100644
--- a/EssentialCSharp.Web.Tests/SitemapXmlHelpersTests.cs
+++ b/EssentialCSharp.Web.Tests/SitemapXmlHelpersTests.cs
@@ -3,20 +3,10 @@
 using EssentialCSharp.Web.Helpers;
 using EssentialCSharp.Web.Services;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
 namespace EssentialCSharp.Web.Tests;
 
-[NotInParallel("SitemapTests")]
-[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
-public class SitemapXmlHelpersTests
+public class SitemapXmlHelpersTests : IntegrationTestBase
 {
-    private readonly WebApplicationFactory _Factory;
-
-    public SitemapXmlHelpersTests(WebApplicationFactory factory)
-    {
-        _Factory = factory;
-    }
-
     [Test]
     public async Task EnsureSitemapHealthy_WithValidSiteMappings_DoesNotThrow()
     {
@@ -73,7 +63,7 @@ public async Task GenerateSitemapXml_DoesNotIncludeIdentityRoutes()
         var baseUrl = "https://test.example.com/";
 
         // Act & Assert
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -99,7 +89,7 @@ public async Task GenerateSitemapXml_IncludesBaseUrl()
         var baseUrl = "https://test.example.com/";
 
         // Act & Assert
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -131,7 +121,7 @@ public async Task GenerateSitemapXml_IncludesSiteMappingsMarkedForXml()
         };
 
         // Act & Assert
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -153,7 +143,7 @@ public async Task GenerateSitemapXml_DoesNotIncludeIndexRoutes()
         var baseUrl = "https://test.example.com/";
 
         // Act & Assert
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -174,7 +164,7 @@ public async Task GenerateSitemapXml_DoesNotIncludeErrorRoutes()
         var baseUrl = "https://test.example.com/";
 
         // Act & Assert
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -195,7 +185,7 @@ public async Task GenerateSitemapXml_DoesNotIncludeSitemapRoute()
         var baseUrl = "https://test.example.com/";
 
         // Act
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -221,7 +211,7 @@ public async Task GenerateSitemapXml_UsesLastModifiedDateFromSiteMapping()
         };
 
         // Act
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
@@ -244,7 +234,7 @@ public async Task GenerateSitemapXml_DoesNotSetLastModifiedDateWhenSiteMappingDa
         };
 
         // Act
-        var routeConfigurationService = _Factory.Services.GetRequiredService<IRouteConfigurationService>();
+        var routeConfigurationService = Factory.Services.GetRequiredService<IRouteConfigurationService>();
         SitemapXmlHelpers.GenerateSitemapXml(
             siteMappings,
             routeConfigurationService,
diff --git a/EssentialCSharp.Web.Tests/WebApplicationFactory.cs b/EssentialCSharp.Web.Tests/WebApplicationFactory.cs
index 287150ee..db0feeb3 100644
--- a/EssentialCSharp.Web.Tests/WebApplicationFactory.cs
+++ b/EssentialCSharp.Web.Tests/WebApplicationFactory.cs
@@ -1,9 +1,9 @@
+using System.Collections.Concurrent;
 using System.Data.Common;
 using EssentialCSharp.Web.Data;
 using EssentialCSharp.Web.Services;
-using TUnit.Core.Interfaces;
+using TUnit.AspNetCore;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Data.Sqlite;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Infrastructure;
@@ -12,19 +12,12 @@
 
 namespace EssentialCSharp.Web.Tests;
 
-public sealed class WebApplicationFactory : WebApplicationFactory<Program>, IAsyncInitializer
+public sealed class WebApplicationFactory : TestWebApplicationFactory<Program>
 {
-    public Task InitializeAsync()
-    {
-        // Force eager server initialization before tests run.
-        // This is thread-safe and prevents race conditions from parallel tests
-        // calling CreateClient() concurrently during lazy init.
-        _ = Server;
-        return Task.CompletedTask;
-    }
-
     private static string SqlConnectionString => $"DataSource=file:{Guid.NewGuid()}?mode=memory&cache=shared";
-    private SqliteConnection? _Connection;
+
+    // Each per-test factory's ConfigureWebHost creates a new connection; track all for disposal.
+    private readonly ConcurrentBag<SqliteConnection> _connections = [];
 
     protected override void ConfigureWebHost(IWebHostBuilder builder)
     {
@@ -58,12 +51,15 @@ protected override void ConfigureWebHost(IWebHostBuilder builder)
                 services.Remove(migrationServiceDescriptor);
             }
 
-            _Connection = new SqliteConnection(SqlConnectionString);
-            _Connection.Open();
+            // Capture in a local variable so each per-test factory's closure binds
+            // to its own connection, not to a shared field that gets overwritten.
+            SqliteConnection connection = new(SqlConnectionString);
+            connection.Open();
+            _connections.Add(connection);
 
             services.AddDbContext<EssentialCSharpWebContext>(options =>
             {
-                options.UseSqlite(_Connection);
+                options.UseSqlite(connection);
             });
 
             using ServiceProvider serviceProvider = services.BuildServiceProvider();
@@ -80,48 +76,25 @@ protected override void ConfigureWebHost(IWebHostBuilder builder)
         });
     }
 
-    /// <summary>
-    /// Executes an action within a service scope, handling scope creation and cleanup automatically.
-    /// </summary>
-    /// <typeparam name="T">The return type of the action</typeparam>
-    /// <param name="action">The action to execute with the scoped service provider</param>
-    /// <returns>The result of the action</returns>
-    public T InServiceScope<T>(Func<IServiceProvider, T> action)
-    {
-        var factory = Services.GetRequiredService<IServiceScopeFactory>();
-        using var scope = factory.CreateScope();
-        return action(scope.ServiceProvider);
-    }
-
-    /// <summary>
-    /// Executes an action within a service scope, handling scope creation and cleanup automatically.
-    /// </summary>
-    /// <param name="action">The action to execute with the scoped service provider</param>
-    public void InServiceScope(Action<IServiceProvider> action)
-    {
-        var factory = Services.GetRequiredService<IServiceScopeFactory>();
-        using var scope = factory.CreateScope();
-        action(scope.ServiceProvider);
-    }
+    private int _connectionsDisposed;
 
     public override async ValueTask DisposeAsync()
     {
         await base.DisposeAsync().ConfigureAwait(false);
-        if (_Connection != null)
+        if (Interlocked.Exchange(ref _connectionsDisposed, 1) == 0)
         {
-            await _Connection.DisposeAsync().ConfigureAwait(false);
-            _Connection = null;
+            foreach (SqliteConnection connection in _connections)
+                await connection.DisposeAsync().ConfigureAwait(false);
         }
-        GC.SuppressFinalize(this);
     }
 
     protected override void Dispose(bool disposing)
     {
         base.Dispose(disposing);
-        if (disposing)
+        if (disposing && Interlocked.Exchange(ref _connectionsDisposed, 1) == 0)
         {
-            _Connection?.Dispose();
-            _Connection = null;
+            foreach (SqliteConnection connection in _connections)
+                connection.Dispose();
         }
     }
 }