github · dereklegenzoff · Jun 17, 2026 · Jun 18, 2026
@@ -963,6 +963,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 toolFilter.AvailableTools,
                 toolFilter.ExcludedTools,
                 config.Provider,
+                config.Capi,
                 config.EnableSessionTelemetry,
                 config.OnPermissionRequest != null ? true : null,
                 config.OnUserInputRequest != null ? true : null,
@@ -1159,6 +1160,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 toolFilter.AvailableTools,
                 toolFilter.ExcludedTools,
                 config.Provider,
+                config.Capi,
                 config.EnableSessionTelemetry,
                 config.OnPermissionRequest != null ? true : null,
                 config.OnUserInputRequest != null ? true : null,
@@ -2355,6 +2357,7 @@ internal record CreateSessionRequest(
         IList<string>? AvailableTools,
         IList<string>? ExcludedTools,
         ProviderConfig? Provider,
+        CapiSessionOptions? Capi,
         bool? EnableSessionTelemetry,
         bool? RequestPermission,
         bool? RequestUserInput,
@@ -2445,6 +2448,7 @@ internal record ResumeSessionRequest(
         IList<string>? AvailableTools,
         IList<string>? ExcludedTools,
         ProviderConfig? Provider,
+        CapiSessionOptions? Capi,
         bool? EnableSessionTelemetry,
         bool? RequestPermission,
         bool? RequestUserInput,
@@ -2569,6 +2573,7 @@ internal record HooksInvokeResponse(
     [JsonSerializable(typeof(EmbeddingCacheStorageMode))]
     [JsonSerializable(typeof(ModelCapabilitiesOverride))]
     [JsonSerializable(typeof(ProviderConfig))]
+    [JsonSerializable(typeof(CapiSessionOptions))]
     [JsonSerializable(typeof(ResumeSessionRequest))]
     [JsonSerializable(typeof(ResumeSessionResponse))]
     [JsonSerializable(typeof(SessionCapabilities))]

@@ -1991,6 +1991,15 @@ public sealed class ProviderConfig
     [JsonPropertyName("wireApi")]
     public string? WireApi { get; set; }
 
+    /// <summary>
+    /// Transport for OpenAI Responses requests ("http" or "websockets"). Defaults to "http".
+    /// Set to "websockets" to deliver Responses API requests over a persistent WebSocket
+    /// connection instead of HTTP. Applies to OpenAI-compatible providers using
+    /// <c>wireApi: "responses"</c>.
+    /// </summary>
+    [JsonPropertyName("transport")]
+    public string? Transport { get; set; }
+
     /// <summary>
     /// Base URL of the provider's API endpoint.
     /// </summary>
@@ -2058,6 +2067,26 @@ public sealed class ProviderConfig
     public int? MaxOutputTokens { get; set; }
 }
 
+/// <summary>
+/// Provider-scoped options for the CAPI (Copilot API) provider.
+/// </summary>
+public sealed class CapiSessionOptions
+{
+    /// <summary>
+    /// When <see langword="true"/>, opts out of the WebSocket transport for the CAPI Responses API
+    /// and uses the HTTP Responses transport instead.
+    /// </summary>
+    /// <remarks>
+    /// WebSocket transport is the default for CAPI Responses API requests when the model advertises
+    /// the <c>ws:/responses</c> endpoint. Set this option for users behind proxies where WebSockets
+    /// fail. This is equivalent to setting the <c>COPILOT_CLI_DISABLE_WEBSOCKET_RESPONSES</c>
+    /// environment variable. The option is scoped under the <c>capi</c> namespace because a single
+    /// session can host multiple providers, such as CAPI and BYOK, so transport choice is provider-level.
+    /// </remarks>
+    [JsonPropertyName("disableWebSocketResponses")]
+    public bool? DisableWebSocketResponses { get; set; }
+}
+
 /// <summary>
 /// Azure OpenAI-specific provider options.
 /// </summary>
@@ -2494,6 +2523,7 @@ protected SessionConfigBase(SessionConfigBase? other)
         OnPermissionRequest = other.OnPermissionRequest;
         OnUserInputRequest = other.OnUserInputRequest;
         Provider = other.Provider;
+        Capi = other.Capi;
         EnableSessionTelemetry = other.EnableSessionTelemetry;
         SkipCustomInstructions = other.SkipCustomInstructions;
         CustomAgentsLocalOnly = other.CustomAgentsLocalOnly;
@@ -2649,6 +2679,11 @@ protected SessionConfigBase(SessionConfigBase? other)
     /// <summary>Custom model provider configuration for the session.</summary>
     public ProviderConfig? Provider { get; set; }
 
+    /// <summary>
+    /// CAPI (Copilot API) provider-scoped configuration for the session.
+    /// </summary>
+    public CapiSessionOptions? Capi { get; set; }
+
     /// <summary>
     /// Enables or disables internal session telemetry for this session.
     /// When <c>false</c>, disables session telemetry. When <c>null</c> (the default) or <c>true</c>,
@@ -3554,6 +3589,7 @@ public sealed class SystemMessageTransformRpcResponse
 [JsonSerializable(typeof(PingRequest))]
 [JsonSerializable(typeof(PingResponse))]
 [JsonSerializable(typeof(ProviderConfig))]
+[JsonSerializable(typeof(CapiSessionOptions))]
 [JsonSerializable(typeof(SessionContext))]
 [JsonSerializable(typeof(SessionLifecycleEvent))]
 [JsonSerializable(typeof(SessionLifecycleEventMetadata))]

@@ -82,6 +82,7 @@ public void SessionConfig_Clone_CopiesAllProperties()
             McpOAuthTokenStorage = McpOAuthTokenStorageMode.Persistent,
             CustomAgents = [new CustomAgentConfig { Name = "agent1", Model = "claude-haiku-4.5" }],
             Agent = "agent1",
+            Capi = new CapiSessionOptions { DisableWebSocketResponses = true },
             Cloud = new CloudSessionOptions
             {
                 Repository = new CloudSessionRepository
@@ -123,6 +124,7 @@ public void SessionConfig_Clone_CopiesAllProperties()
         Assert.Equal(original.CustomAgents.Count, clone.CustomAgents!.Count);
         Assert.Equal(original.CustomAgents[0].Model, clone.CustomAgents[0].Model);
         Assert.Equal(original.Agent, clone.Agent);
+        Assert.Same(original.Capi, clone.Capi);
         Assert.Same(original.Cloud, clone.Cloud);
         Assert.Equal(original.DefaultAgent!.ExcludedTools, clone.DefaultAgent!.ExcludedTools);
         Assert.Equal(original.SkillDirectories, clone.SkillDirectories);
@@ -515,4 +517,30 @@ public void ResumeSessionConfig_Clone_CopiesMcpOAuthTokenStorage()
 
         Assert.Equal(McpOAuthTokenStorageMode.Persistent, clone.McpOAuthTokenStorage);
     }
+
+    [Fact]
+    public void SessionConfig_Clone_CopiesCapiOptions()
+    {
+        var original = new SessionConfig
+        {
+            Capi = new CapiSessionOptions { DisableWebSocketResponses = true },
+        };
+
+        var clone = original.Clone();
+
+        Assert.Same(original.Capi, clone.Capi);
+    }
+
+    [Fact]
+    public void ResumeSessionConfig_Clone_CopiesCapiOptions()
+    {
+        var original = new ResumeSessionConfig
+        {
+            Capi = new CapiSessionOptions { DisableWebSocketResponses = true },
+        };
+
+        var clone = original.Clone();
+
+        Assert.Same(original.Capi, clone.Capi);
+    }
 }
@@ -27,7 +27,8 @@ public void ProviderConfig_CanSerializeHeaders_WithSdkOptions()
             ModelId = "gpt-4o",
             WireModel = "my-finetune-v3",
             MaxPromptTokens = 100_000,
-            MaxOutputTokens = 4096
+            MaxOutputTokens = 4096,
+            Transport = "websockets"
         };
 
         var json = JsonSerializer.Serialize(original, options);
@@ -39,6 +40,7 @@ public void ProviderConfig_CanSerializeHeaders_WithSdkOptions()
         Assert.Equal("my-finetune-v3", root.GetProperty("wireModel").GetString());
         Assert.Equal(100_000, root.GetProperty("maxPromptTokens").GetInt32());
         Assert.Equal(4096, root.GetProperty("maxOutputTokens").GetInt32());
+        Assert.Equal("websockets", root.GetProperty("transport").GetString());
 
         var deserialized = JsonSerializer.Deserialize<ProviderConfig>(json, options);
         Assert.NotNull(deserialized);
@@ -48,6 +50,26 @@ public void ProviderConfig_CanSerializeHeaders_WithSdkOptions()
         Assert.Equal("my-finetune-v3", deserialized.WireModel);
         Assert.Equal(100_000, deserialized.MaxPromptTokens);
         Assert.Equal(4096, deserialized.MaxOutputTokens);
+        Assert.Equal("websockets", deserialized.Transport);
+    }
+
+    [Fact]
+    public void CapiSessionOptions_CanSerializeDisableWebSocketResponses_WithSdkOptions()
+    {
+        var options = GetSerializerOptions();
+        var original = new CapiSessionOptions
+        {
+            DisableWebSocketResponses = true
+        };
+
+        var json = JsonSerializer.Serialize(original, options);
+        using var document = JsonDocument.Parse(json);
+        var root = document.RootElement;
+        Assert.True(root.GetProperty("disableWebSocketResponses").GetBoolean());
+
+        var deserialized = JsonSerializer.Deserialize<CapiSessionOptions>(json, options);
+        Assert.NotNull(deserialized);
+        Assert.True(deserialized.DisableWebSocketResponses);
     }
 
     [Fact]
@@ -221,6 +243,57 @@ public void ResumeSessionRequest_CanSerializeInstructionDirectories_WithSdkOptio
         Assert.Equal("C:\\resume-instructions", root.GetProperty("instructionDirectories")[0].GetString());
     }
 
+    [Fact]
+    public void SessionRequests_CanSerializeCapiOptions_WithSdkOptions()
+    {
+        var options = GetSerializerOptions();
+        var capi = new CapiSessionOptions { DisableWebSocketResponses = true };
+
+        var createRequestType = GetNestedType(typeof(CopilotClient), "CreateSessionRequest");
+        var createRequest = CreateInternalRequest(
+            createRequestType,
+            ("SessionId", "session-id"),
+            ("Capi", capi));
+
+        var createJson = JsonSerializer.Serialize(createRequest, createRequestType, options);
+        using var createDocument = JsonDocument.Parse(createJson);
+        Assert.True(createDocument.RootElement.GetProperty("capi").GetProperty("disableWebSocketResponses").GetBoolean());
+
+        var resumeRequestType = GetNestedType(typeof(CopilotClient), "ResumeSessionRequest");
+        var resumeRequest = CreateInternalRequest(
+            resumeRequestType,
+            ("SessionId", "session-id"),
+            ("Capi", capi));
+
+        var resumeJson = JsonSerializer.Serialize(resumeRequest, resumeRequestType, options);
+        using var resumeDocument = JsonDocument.Parse(resumeJson);
+        Assert.True(resumeDocument.RootElement.GetProperty("capi").GetProperty("disableWebSocketResponses").GetBoolean());
+    }
+
+    [Fact]
+    public void SessionRequests_OmitCapiOptions_WhenUnset()
+    {
+        var options = GetSerializerOptions();
+
+        var createRequestType = GetNestedType(typeof(CopilotClient), "CreateSessionRequest");
+        var createRequest = CreateInternalRequest(
+            createRequestType,
+            ("SessionId", "session-id"));
+
+        var createJson = JsonSerializer.Serialize(createRequest, createRequestType, options);
+        using var createDocument = JsonDocument.Parse(createJson);
+        Assert.False(createDocument.RootElement.TryGetProperty("capi", out _));
+
+        var resumeRequestType = GetNestedType(typeof(CopilotClient), "ResumeSessionRequest");
+        var resumeRequest = CreateInternalRequest(
+            resumeRequestType,
+            ("SessionId", "session-id"));
+
+        var resumeJson = JsonSerializer.Serialize(resumeRequest, resumeRequestType, options);
+        using var resumeDocument = JsonDocument.Parse(resumeJson);
+        Assert.False(resumeDocument.RootElement.TryGetProperty("capi", out _));
+    }
+
     [Fact]
     public void SessionRequests_CanSerializeReasoningSummary_WithSdkOptions()
     {

@@ -681,6 +681,7 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 	req.ExcludedTools = excludedTools
 	req.ToolFilterPrecedence = precedence
 	req.Provider = config.Provider
+	req.Capi = config.Capi
 	req.EnableSessionTelemetry = config.EnableSessionTelemetry
 	req.SkipCustomInstructions = config.SkipCustomInstructions
 	req.CustomAgentsLocalOnly = config.CustomAgentsLocalOnly
@@ -976,6 +977,7 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 	req.SystemMessage = wireSystemMessage
 	req.Tools = config.Tools
 	req.Provider = config.Provider
+	req.Capi = config.Capi
 	req.EnableSessionTelemetry = config.EnableSessionTelemetry
 	req.SkipCustomInstructions = config.SkipCustomInstructions
 	req.CustomAgentsLocalOnly = config.CustomAgentsLocalOnly