Expose new session options across SDKs

dotnet/src/Client.cs

@@ -980,9 +980,11 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 config.ReasoningSummary,
                 config.ContextTier,
                 config.Tools?.Select(ToolDefinition.FromAIFunction).ToList(),
+                config.EnableCitations,
                 wireSystemMessage,
                 toolFilter.AvailableTools,
                 toolFilter.ExcludedTools,
+                config.ExcludedBuiltInAgents,
                 config.Provider,
                 config.Capi,
                 config.EnableSessionTelemetry,
@@ -1013,6 +1015,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 config.SkillDirectories,
                 config.DisabledSkills,
                 config.InfiniteSessions,
+                config.SessionLimits,
                 Commands: config.Commands?.Select(c => new CommandWireDefinition(c.Name, c.Description)).ToList(),
                 RequestElicitation: config.OnElicitationRequest != null,
                 RequestMcpApps: config.EnableMcpApps ? true : null,
@@ -1189,9 +1192,11 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 config.ReasoningSummary,
                 config.ContextTier,
                 config.Tools?.Select(ToolDefinition.FromAIFunction).ToList(),
+                config.EnableCitations,
                 wireSystemMessage,
                 toolFilter.AvailableTools,
                 toolFilter.ExcludedTools,
+                config.ExcludedBuiltInAgents,
                 config.Provider,
                 config.Capi,
                 config.EnableSessionTelemetry,
@@ -1223,6 +1228,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 config.SkillDirectories,
                 config.DisabledSkills,
                 config.InfiniteSessions,
+                config.SessionLimits,
                 Commands: config.Commands?.Select(c => new CommandWireDefinition(c.Name, c.Description)).ToList(),
                 RequestElicitation: config.OnElicitationRequest != null,
                 RequestMcpApps: config.EnableMcpApps ? true : null,
@@ -2431,9 +2437,11 @@ internal record CreateSessionRequest(
         ReasoningSummary? ReasoningSummary,
         ContextTier? ContextTier,
         IList<ToolDefinition>? Tools,
+        bool? EnableCitations,
         SystemMessageConfig? SystemMessage,
         IList<string>? AvailableTools,
         IList<string>? ExcludedTools,
+        [property: JsonPropertyName("excludedBuiltinAgents")] IList<string>? ExcludedBuiltInAgents,
         ProviderConfig? Provider,
         CapiSessionOptions? Capi,
         bool? EnableSessionTelemetry,
@@ -2464,6 +2472,7 @@ internal record CreateSessionRequest(
         IList<string>? SkillDirectories,
         IList<string>? DisabledSkills,
         InfiniteSessionConfig? InfiniteSessions,
+        SessionLimitsConfig? SessionLimits,
         IList<CommandWireDefinition>? Commands = null,
         bool? RequestElicitation = null,
         bool? RequestMcpApps = null,
@@ -2525,9 +2534,11 @@ internal record ResumeSessionRequest(
         ReasoningSummary? ReasoningSummary,
         ContextTier? ContextTier,
         IList<ToolDefinition>? Tools,
+        bool? EnableCitations,
         SystemMessageConfig? SystemMessage,
         IList<string>? AvailableTools,
         IList<string>? ExcludedTools,
+        [property: JsonPropertyName("excludedBuiltinAgents")] IList<string>? ExcludedBuiltInAgents,
         ProviderConfig? Provider,
         CapiSessionOptions? Capi,
         bool? EnableSessionTelemetry,
@@ -2559,6 +2570,7 @@ internal record ResumeSessionRequest(
         IList<string>? SkillDirectories,
         IList<string>? DisabledSkills,
         InfiniteSessionConfig? InfiniteSessions,
+        SessionLimitsConfig? SessionLimits,
         IList<CommandWireDefinition>? Commands = null,
         bool? RequestElicitation = null,
         bool? RequestMcpApps = null,
@@ -2660,6 +2672,7 @@ internal record HooksInvokeResponse(
     [JsonSerializable(typeof(CapiSessionOptions))]
     [JsonSerializable(typeof(NamedProviderConfig))]
     [JsonSerializable(typeof(ProviderModelConfig))]
+    [JsonSerializable(typeof(SessionLimitsConfig))]
     [JsonSerializable(typeof(ResumeSessionRequest))]
     [JsonSerializable(typeof(ResumeSessionResponse))]
     [JsonSerializable(typeof(SessionCapabilities))]

dotnet/src/Types.cs

@@ -2758,6 +2758,7 @@ protected SessionConfigBase(SessionConfigBase? other)
         DefaultAgent = other.DefaultAgent;
         Agent = other.Agent;
         DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
+        EnableCitations = other.EnableCitations;
         EnableConfigDiscovery = other.EnableConfigDiscovery;
         SkipEmbeddingRetrieval = other.SkipEmbeddingRetrieval;
         EmbeddingCacheStorage = other.EmbeddingCacheStorage;
@@ -2768,6 +2769,7 @@ protected SessionConfigBase(SessionConfigBase? other)
         EnableSessionStore = other.EnableSessionStore;
         EnableSkills = other.EnableSkills;
         EnableMcpApps = other.EnableMcpApps;
+        ExcludedBuiltInAgents = other.ExcludedBuiltInAgents is not null ? [.. other.ExcludedBuiltInAgents] : null;
         ExcludedTools = other.ExcludedTools is not null ? [.. other.ExcludedTools] : null;
         Hooks = other.Hooks;
         InfiniteSessions = other.InfiniteSessions;
@@ -2815,6 +2817,7 @@ protected SessionConfigBase(SessionConfigBase? other)
         SkillDirectories = other.SkillDirectories is not null ? [.. other.SkillDirectories] : null;
         PluginDirectories = other.PluginDirectories is not null ? [.. other.PluginDirectories] : null;
         InstructionDirectories = other.InstructionDirectories is not null ? [.. other.InstructionDirectories] : null;
+        SessionLimits = other.SessionLimits;
         Streaming = other.Streaming;
         IncludeSubAgentStreamingEvents = other.IncludeSubAgentStreamingEvents;
         SystemMessage = other.SystemMessage;
@@ -2853,6 +2856,16 @@ protected SessionConfigBase(SessionConfigBase? other)
     /// <summary>Per-property overrides for model capabilities, deep-merged over runtime defaults.</summary>
     public ModelCapabilitiesOverride? ModelCapabilities { get; set; }
 
+    /// <summary>
+    /// Enables native model citations for models that support them.
+    /// </summary>
+    /// <remarks>
+    /// Citations are experimental, off by default, and currently available for Anthropic models.
+    /// This option may change or be removed while citation support is experimental.
+    /// </remarks>
+    [Experimental(Diagnostics.Experimental)]
+    public bool? EnableCitations { get; set; }
+
     /// <summary>
     /// Override the default configuration directory location.
     /// When specified, the session will use this directory for storing config and state.
@@ -2945,6 +2958,16 @@ protected SessionConfigBase(SessionConfigBase? other)
     /// <summary>List of tool names to exclude from the session.</summary>
     public IList<string>? ExcludedTools { get; set; }
 
+    /// <summary>
+    /// Built-in subagent names to exclude from this session.
+    /// </summary>
+    /// <remarks>
+    /// Excluded built-ins are hidden from agent discovery and cannot be dispatched unless a
+    /// custom agent with the same name is available.
+    /// </remarks>
+    [JsonPropertyName("excludedBuiltinAgents")]
+    public IList<string>? ExcludedBuiltInAgents { get; set; }
+
     /// <summary>Custom model provider configuration for the session.</summary>
     public ProviderConfig? Provider { get; set; }
 
@@ -3137,6 +3160,16 @@ protected SessionConfigBase(SessionConfigBase? other)
     /// </summary>
     public InfiniteSessionConfig? InfiniteSessions { get; set; }
 
+    /// <summary>
+    /// Optional limits for the session's current accounting window.
+    /// </summary>
+    /// <remarks>
+    /// These settings only model the caller's configured limits. Enforcement and
+    /// limit-exhaustion behavior are handled by the runtime.
+    /// </remarks>
+    [Experimental(Diagnostics.Experimental)]
+    public SessionLimitsConfig? SessionLimits { get; set; }
+
     /// <summary>
     /// Configuration for handling large tool outputs. When a tool produces
     /// output exceeding the configured size, the output is written to a temp

dotnet/test/E2E/CopilotRequestE2EProvider.cs

@@ -49,15 +49,14 @@ internal sealed class RecordingRequestHandler : CopilotRequestHandler
     protected override async Task<HttpResponseMessage> SendRequestAsync(HttpRequestMessage request, CopilotRequestContext ctx)
     {
         var url = request.RequestUri!.ToString();
-        _records.Enqueue(new InterceptedRequest(url, ctx.SessionId));
-
         var bodyText = request.Content is null
             ? string.Empty
 #if NET8_0_OR_GREATER
             : await request.Content.ReadAsStringAsync(ctx.CancellationToken).ConfigureAwait(false);
 #else
             : await request.Content.ReadAsStringAsync().ConfigureAwait(false);
 #endif
+        _records.Enqueue(new InterceptedRequest(url, ctx.SessionId, bodyText));
 
         return IsInferenceUrl(url)
             ? BuildInferenceResponse(url, bodyText)
@@ -95,6 +94,11 @@ private static HttpResponseMessage BuildInferenceResponse(string url, string bod
             return Sse(string.Concat(ChatCompletionStreamEvents));
         }
 
+        if (u.EndsWith("/messages", StringComparison.Ordinal))
+        {
+            return Json(BufferedAnthropicMessageJson);
+        }
+
         // /chat/completions non-streaming (and any other inference url) — buffered JSON.
         return Json(BufferedChatCompletionJson);
     }
@@ -160,9 +164,12 @@ internal static HttpResponseMessage BuildNonInferenceResponse(string url)
     private static readonly string BufferedChatCompletionJson =
         "{\"id\":\"chatcmpl-stub-1\",\"object\":\"chat.completion\",\"created\":1,\"model\":\"claude-sonnet-4.5\",\"choices\":[{\"index\":0,\"message\":{\"role\":\"assistant\",\"content\":\"" + SyntheticText + "\"},\"finish_reason\":\"stop\"}],\"usage\":{\"prompt_tokens\":5,\"completion_tokens\":7,\"total_tokens\":12}}";
 
+    private static readonly string BufferedAnthropicMessageJson =
+        "{\"id\":\"msg_stub_1\",\"type\":\"message\",\"role\":\"assistant\",\"model\":\"claude-sonnet-4.5\",\"content\":[{\"type\":\"text\",\"text\":\"" + SyntheticText + "\"}],\"stop_reason\":\"end_turn\",\"stop_sequence\":null,\"usage\":{\"input_tokens\":5,\"output_tokens\":7}}";
+
     private const string ModelCatalogJson =
         "{\"data\":[{\"id\":\"claude-sonnet-4.5\",\"name\":\"Claude Sonnet 4.5\",\"object\":\"model\",\"vendor\":\"Anthropic\",\"version\":\"1\",\"preview\":false,\"model_picker_enabled\":true,\"capabilities\":{\"type\":\"chat\",\"family\":\"claude-sonnet-4.5\",\"tokenizer\":\"o200k_base\",\"limits\":{\"max_context_window_tokens\":200000,\"max_output_tokens\":8192},\"supports\":{\"streaming\":true,\"tool_calls\":true,\"parallel_tool_calls\":true,\"vision\":true}}}]}";
 }
 
 /// <summary>A single request the callback intercepted.</summary>
-internal sealed record InterceptedRequest(string Url, string? SessionId);
+internal sealed record InterceptedRequest(string Url, string? SessionId, string Body);