Add .NET BYOK E2E coverage

.github/instructions/dotnet-e2e.instructions.md

@@ -0,0 +1,9 @@
+---
+applyTo: "dotnet/test/E2E/**/*.cs"
+---
+
+# .NET E2E test instructions
+
+- Create and resume sessions through `E2ETestContext` using `Ctx.CreateSessionAsync` and `Ctx.ResumeSessionAsync`. Do not call these methods directly on `CopilotClient`; the context applies the backend selected by the E2E matrix while preserving providers explicitly configured by the test.
+- Create clients with `Ctx.CreateClient` so they receive the harness environment, CLI path, authentication defaults, transport handling, and lifecycle tracking.
+- Instantiate `CopilotClient` directly only when client construction, startup, shutdown, or disposal is the behavior under test. Keep cleanup explicit in those tests, and still create any sessions through `Ctx` so they participate in backend coverage.

.github/workflows/dotnet-sdk-tests.yml

@@ -28,19 +28,35 @@ permissions:
 
 jobs:
   test:
-    name: ".NET SDK Tests (${{ matrix.os }}, ${{ matrix.transport }})"
+    name: ".NET SDK Tests (${{ matrix.os }}, ${{ matrix.transport }}, ${{ matrix.backend }})"
     if: github.event.repository.fork == false
     env:
       POWERSHELL_UPDATECHECK: Off
+      COPILOT_SDK_E2E_BACKEND: ${{ matrix.backend }}
+      DOTNET_TEST_FILTER: ${{ matrix.test-filter }}
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         transport: ["default", "inprocess"]
-        # TODO: Re-enable after fixing in-process sqlite file locking on shutdown on Windows
+        backend: [capi]
+        # TODO: Re-enable after fixing in-process sqlite file locking on shutdown on Windows.
         exclude:
           - os: windows-latest
             transport: "inprocess"
+        include:
+          - os: ubuntu-latest
+            transport: inprocess
+            backend: anthropic-messages
+            test-filter: "FullyQualifiedName~GitHub.Copilot.Test.E2E&E2EBackend!=SelfConfiguredBackend&E2EBackend!=CapiOnly"
+          - os: ubuntu-latest
+            transport: inprocess
+            backend: openai-responses
+            test-filter: "FullyQualifiedName~GitHub.Copilot.Test.E2E&E2EBackend!=SelfConfiguredBackend&E2EBackend!=CapiOnly"
+          - os: ubuntu-latest
+            transport: inprocess
+            backend: openai-completions
+            test-filter: "FullyQualifiedName~GitHub.Copilot.Test.E2E&E2EBackend!=SelfConfiguredBackend&E2EBackend!=CapiOnly"
     runs-on: ${{ matrix.os }}
     defaults:
       run:
@@ -92,4 +108,9 @@ jobs:
       - name: Run .NET SDK tests
         env:
           COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
-        run: dotnet test --no-build -v n
+        run: |
+          args=(--no-build -v n)
+          if [[ -n "$DOTNET_TEST_FILTER" ]]; then
+            args+=(--filter "$DOTNET_TEST_FILTER")
+          fi
+          dotnet test "${args[@]}"

dotnet/test/AssemblyInfo.cs

@@ -5,7 +5,7 @@
 using Xunit;
 using GitHub.Copilot.Test.Harness;
 
-// Each E2E test class fixture spins up its own Copilot CLI subprocess plus a CapiProxy
+// Each E2E test class fixture spins up its own Copilot CLI subprocess plus a ReplayProxy
 // (replaying HTTP proxy) Node.js subprocess. With ~25 test classes, running them in parallel
 // would launch ~50 long-lived Node.js processes simultaneously and exhaust both file
 // descriptors and memory on developer machines and CI runners (especially Windows). Tests

dotnet/test/E2E/ByokBearerTokenProviderE2ETests.cs

@@ -36,6 +36,7 @@ namespace GitHub.Copilot.Test.E2E;
 ///   and the resulting token reaches that provider's endpoint.</item>
 /// </list>
 /// </remarks>
+[Trait(E2ETestTraits.Backend, E2ETestTraits.SelfConfiguredBackend)]
 public class ByokBearerTokenProviderE2ETests(E2ETestFixture fixture, ITestOutputHelper output)
     : E2ETestBase(fixture, "byok_bearer_token_provider", output)
 {

dotnet/test/E2E/ClientE2ETests.cs

@@ -9,8 +9,10 @@ namespace GitHub.Copilot.Test.E2E;
 
 // These tests bypass E2ETestBase because they are about how the CLI subprocess is started
 // Other test classes should instead inherit from E2ETestBase
-public class ClientE2ETests
+public class ClientE2ETests(E2ETestFixture fixture) : IClassFixture<E2ETestFixture>
 {
+    private E2ETestContext Ctx => fixture.Ctx;
+
     [Theory]
     [InlineData(true)]   // stdio transport
     [InlineData(false)]  // TCP transport
@@ -66,7 +68,7 @@ public async Task Should_Force_Stop_Without_Cleanup(bool useStdio)
     {
         using var client = new CopilotClient(new CopilotClientOptions { Connection = useStdio ? RuntimeConnection.ForStdio() : RuntimeConnection.ForTcp() });
 
-        await client.CreateSessionAsync(new SessionConfig { OnPermissionRequest = PermissionHandler.ApproveAll });
+        await Ctx.CreateSessionAsync(client, new SessionConfig { OnPermissionRequest = PermissionHandler.ApproveAll });
         await client.ForceStopAsync();
     }
 
@@ -165,7 +167,7 @@ public async Task Should_List_Models_When_Authenticated(bool useStdio)
     public async Task Should_Not_Throw_When_Disposing_Session_After_Stopping_Client(bool useStdio)
     {
         await using var client = new CopilotClient(new CopilotClientOptions { Connection = useStdio ? RuntimeConnection.ForStdio() : RuntimeConnection.ForTcp() });
-        await using var session = await client.CreateSessionAsync(new SessionConfig { OnPermissionRequest = PermissionHandler.ApproveAll });
+        await using var session = await Ctx.CreateSessionAsync(client, new SessionConfig { OnPermissionRequest = PermissionHandler.ApproveAll });
 
         await client.StopAsync();
     }
@@ -201,7 +203,7 @@ public async Task Should_Report_Error_With_Stderr_When_CLI_Fails_To_Start(bool u
         // Verify subsequent calls also fail (don't hang)
         var ex2 = await Assert.ThrowsAnyAsync<Exception>(async () =>
         {
-            var session = await client.CreateSessionAsync(new SessionConfig { OnPermissionRequest = PermissionHandler.ApproveAll });
+            var session = await Ctx.CreateSessionAsync(client, new SessionConfig { OnPermissionRequest = PermissionHandler.ApproveAll });
             await session.SendAsync(new MessageOptions { Prompt = "test" });
         });
         Assert.True(
@@ -219,7 +221,7 @@ public async Task Should_Report_Error_With_Stderr_When_CLI_Fails_To_Start(bool u
     public async Task Should_Allow_CreateSession_Called_Without_PermissionHandler(bool useStdio)
     {
         await using var client = new CopilotClient(new CopilotClientOptions { Connection = useStdio ? RuntimeConnection.ForStdio() : RuntimeConnection.ForTcp() });
-        await using var session = await client.CreateSessionAsync(new SessionConfig());
+        await using var session = await Ctx.CreateSessionAsync(client, new SessionConfig());
 
         Assert.NotNull(session.SessionId);
     }
@@ -234,7 +236,7 @@ public async Task Should_Allow_ResumeSession_Called_Without_PermissionHandler()
         {
             Connection = RuntimeConnection.ForTcp(connectionToken: connectionToken),
         });
-        await using var originalSession = await client.CreateSessionAsync(new SessionConfig());
+        await using var originalSession = await ctx.CreateSessionAsync(client, new SessionConfig());
 
         var port = client.RuntimePort
             ?? throw new InvalidOperationException("Client must be using TCP transport to support multi-client resume.");
@@ -243,7 +245,7 @@ public async Task Should_Allow_ResumeSession_Called_Without_PermissionHandler()
         {
             Connection = RuntimeConnection.ForUri($"localhost:{port}", connectionToken: connectionToken),
         });
-        await using var resumedSession = await resumeClient.ResumeSessionAsync(originalSession.SessionId, new());
+        await using var resumedSession = await ctx.ResumeSessionAsync(resumeClient, originalSession.SessionId, new());
 
         Assert.Equal(originalSession.SessionId, resumedSession.SessionId);
     }

dotnet/test/E2E/ClientOptionsE2ETests.cs

@@ -7,6 +7,7 @@
 using System.Net;
 using System.Net.Sockets;
 using System.Text.Json;
+using GitHub.Copilot.Test.Harness;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -41,7 +42,7 @@ public async Task Should_Use_Client_Cwd_For_Default_WorkingDirectory()
             WorkingDirectory = clientCwd,
         });
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });
@@ -110,7 +111,7 @@ public async Task Should_Propagate_Process_Options_To_Spawned_Cli()
         Assert.Equal("dotnet-sdk-e2e", capturedEnv.GetProperty("COPILOT_OTEL_SOURCE_NAME").GetString());
         Assert.Equal("true", capturedEnv.GetProperty("OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT").GetString());
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             EnableConfigDiscovery = true,
             IncludeSubAgentStreamingEvents = false,
@@ -139,7 +140,7 @@ public async Task Should_Forward_EnableSessionTelemetry_In_Wire_Request()
         await client.StartAsync();
 
         // When explicitly set to false, it should appear in the wire request
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             EnableSessionTelemetry = false,
             OnPermissionRequest = PermissionHandler.ApproveAll,
@@ -166,7 +167,7 @@ public async Task Should_Omit_EnableSessionTelemetry_When_Not_Set()
         await client.StartAsync();
 
         // When omitted (null/default), the field should not be present in the wire request
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });
@@ -191,7 +192,7 @@ public async Task Should_Forward_Granular_Multitenancy_Fields_In_Create_Wire_Req
 
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             SkipEmbeddingRetrieval = false,
             OrganizationCustomInstructions = "Follow org policy.",
@@ -219,6 +220,7 @@ public async Task Should_Forward_Granular_Multitenancy_Fields_In_Create_Wire_Req
     }
 
     [Fact]
+    [Trait(E2ETestTraits.Backend, E2ETestTraits.SelfConfiguredBackend)]
     public async Task Should_Forward_Advanced_Session_Options_In_Create_Wire_Request()
     {
         var (cliPath, capturePath) = await CreateFakeCliCaptureAsync();
@@ -232,7 +234,7 @@ public async Task Should_Forward_Advanced_Session_Options_In_Create_Wire_Request
 
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             ClientName = "advanced-create-client",
             Model = "claude-sonnet-4.5",
@@ -366,6 +368,7 @@ public async Task Should_Forward_Advanced_Session_Options_In_Create_Wire_Request
     }
 
     [Fact]
+    [Trait(E2ETestTraits.Backend, E2ETestTraits.SelfConfiguredBackend)]
     public async Task Should_Forward_Singular_Provider_Options_In_Create_Wire_Request()
     {
         var (cliPath, capturePath) = await CreateFakeCliCaptureAsync();
@@ -378,7 +381,7 @@ public async Task Should_Forward_Singular_Provider_Options_In_Create_Wire_Reques
 
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             Model = "claude-sonnet-4.5",
             Provider = new ProviderConfig
@@ -432,7 +435,7 @@ public async Task Should_Apply_Empty_Mode_Defaults_To_CreateSession_Wire_Request
 
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
             AvailableTools = new ToolSet().AddBuiltIn(BuiltInTools.Isolated),
@@ -471,7 +474,7 @@ public async Task Should_Propagate_Activity_TraceContext_To_Session_Create_And_S
         activity.TraceStateString = "vendor=create-send";
         activity.Start();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });
@@ -555,7 +558,7 @@ public async Task Should_Propagate_Activity_TraceContext_To_Session_Resume()
         activity.TraceStateString = "vendor=resume";
         activity.Start();
 
-        var session = await client.ResumeSessionAsync("trace-resume-session", new ResumeSessionConfig
+        var session = await Ctx.ResumeSessionAsync(client, "trace-resume-session", new ResumeSessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });
@@ -582,7 +585,7 @@ public async Task Should_Forward_Granular_Multitenancy_Fields_In_Resume_Wire_Req
 
         await client.StartAsync();
 
-        var session = await client.ResumeSessionAsync("resume-session", new ResumeSessionConfig
+        var session = await Ctx.ResumeSessionAsync(client, "resume-session", new ResumeSessionConfig
         {
             SkipEmbeddingRetrieval = false,
             OrganizationCustomInstructions = "Resume org policy.",
@@ -624,7 +627,7 @@ public async Task Should_Forward_Advanced_Session_Options_In_Resume_Wire_Request
 
         await client.StartAsync();
 
-        var session = await client.ResumeSessionAsync("advanced-resume-session", new ResumeSessionConfig
+        var session = await Ctx.ResumeSessionAsync(client, "advanced-resume-session", new ResumeSessionConfig
         {
             ClientName = "advanced-resume-client",
             Model = "claude-haiku-4.5",
@@ -706,7 +709,7 @@ public async Task Should_Apply_Empty_Mode_Defaults_To_ResumeSession_Wire_Request
 
         await client.StartAsync();
 
-        var session = await client.ResumeSessionAsync("resume-empty-session", new ResumeSessionConfig
+        var session = await Ctx.ResumeSessionAsync(client, "resume-empty-session", new ResumeSessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
             AvailableTools = new ToolSet().AddBuiltIn(BuiltInTools.Isolated),

dotnet/test/E2E/CopilotRequestCancelErrorE2ETests.cs

@@ -54,7 +54,7 @@ public async Task Reports_A_Thrown_Callback_Error_Instead_Of_Hanging()
         await using var client = CreateClientWith(handler);
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });
@@ -81,7 +81,7 @@ public async Task Observes_Runtime_Cancellation_Of_An_In_Flight_Inference_Reques
         await using var client = CreateClientWith(handler);
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });

dotnet/test/E2E/CopilotRequestSessionIdE2ETests.cs

@@ -28,13 +28,14 @@ private CopilotClient CreateClientWith(RecordingRequestHandler provider) =>
         });
 
     [Fact]
+    [Trait(E2ETestTraits.Backend, E2ETestTraits.CapiOnly)]
     public async Task Threads_The_Session_Id_Into_A_Capi_Session_Inference_Request()
     {
         var provider = new RecordingRequestHandler();
         await using var client = CreateClientWith(provider);
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });
@@ -64,13 +65,14 @@ public async Task Threads_The_Session_Id_Into_A_Capi_Session_Inference_Request()
     }
 
     [Fact]
+    [Trait(E2ETestTraits.Backend, E2ETestTraits.SelfConfiguredBackend)]
     public async Task Threads_The_Session_Id_Into_A_Byok_Session_Inference_Request()
     {
         var provider = new RecordingRequestHandler();
         await using var client = CreateClientWith(provider);
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
             // BYOK providers require an explicit model id.

dotnet/test/E2E/CopilotRequestWebSocketE2ETests.cs

@@ -31,6 +31,7 @@ namespace GitHub.Copilot.Test.E2E;
 /// message. Without the eager start the turn never completes and this test
 /// times out.
 /// </remarks>
+[Trait(E2ETestTraits.Backend, E2ETestTraits.SelfConfiguredBackend)]
 public class CopilotRequestWebSocketE2ETests(E2ETestFixture fixture, ITestOutputHelper output)
     : E2ETestBase(fixture, "copilot_request_websocket", output)
 {
@@ -54,7 +55,7 @@ public async Task Services_A_WebSocket_Turn_End_To_End_Via_The_Request_Handler()
         }, environment: env);
         await client.StartAsync();
 
-        var session = await client.CreateSessionAsync(new SessionConfig
+        var session = await Ctx.CreateSessionAsync(client, new SessionConfig
         {
             OnPermissionRequest = PermissionHandler.ApproveAll,
         });

dotnet/test/E2E/GitHubTelemetryForwardingE2ETests.cs

@@ -12,6 +12,9 @@ namespace GitHub.Copilot.Test.E2E;
 
 #pragma warning disable GHCP001 // GitHub telemetry forwarding is experimental.
 
+// TODO(BYOK): Anthropic Messages produced no GitHub telemetry notification. Determine whether
+// provider-backed sessions should forward the same telemetry before keeping this CAPI-only.
+[Trait(E2ETestTraits.Backend, E2ETestTraits.CapiOnly)]
 public class GitHubTelemetryForwardingE2ETests(E2ETestFixture fixture, ITestOutputHelper output)
     : E2ETestBase(fixture, "github_telemetry", output)
 {
@@ -32,7 +35,7 @@ public async Task Should_Forward_GitHub_Telemetry_For_A_Live_Session()
         CopilotSession? session = null;
         try
         {
-            session = await client.CreateSessionAsync(new SessionConfig
+            session = await Ctx.CreateSessionAsync(client, new SessionConfig
             {
                 OnPermissionRequest = PermissionHandler.ApproveAll,
             });