feat: add clientName to SessionConfig across all SDKs

Add clientName as an optional field to SessionConfig and
ResumeSessionConfig in all four SDK languages (Node.js, Python, Go,
.NET). This allows SDK consumers to identify their application, which
is included in the User-Agent header for API requests.

The CLI server protocol already supports clientName on both
session.create and session.resume requests, but the SDK types were
not exposing it.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: devm33

dotnet/src/Client.cs

@@ -371,6 +371,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig? config = nul
         var request = new CreateSessionRequest(
             config?.Model,
             config?.SessionId,
+            config?.ClientName,
             config?.ReasoningEffort,
             config?.Tools?.Select(ToolDefinition.FromAIFunction).ToList(),
             config?.SystemMessage,
@@ -454,6 +455,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
 
         var request = new ResumeSessionRequest(
             sessionId,
+            config?.ClientName,
             config?.Model,
             config?.ReasoningEffort,
             config?.Tools?.Select(ToolDefinition.FromAIFunction).ToList(),
@@ -1375,6 +1377,7 @@ public static string Escape(string arg)
     internal record CreateSessionRequest(
         string? Model,
         string? SessionId,
+        string? ClientName,
         string? ReasoningEffort,
         List<ToolDefinition>? Tools,
         SystemMessageConfig? SystemMessage,
@@ -1409,6 +1412,7 @@ internal record CreateSessionResponse(
 
     internal record ResumeSessionRequest(
         string SessionId,
+        string? ClientName,
         string? Model,
         string? ReasoningEffort,
         List<ToolDefinition>? Tools,

dotnet/src/Types.cs

@@ -745,6 +745,7 @@ protected SessionConfig(SessionConfig? other)
         if (other is null) return;
 
         AvailableTools = other.AvailableTools is not null ? [.. other.AvailableTools] : null;
+        ClientName = other.ClientName;
         ConfigDir = other.ConfigDir;
         CustomAgents = other.CustomAgents is not null ? [.. other.CustomAgents] : null;
         DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
@@ -768,6 +769,13 @@ protected SessionConfig(SessionConfig? other)
     }
 
     public string? SessionId { get; set; }
+
+    /// <summary>
+    /// Client name to identify the application using the SDK.
+    /// Included in the User-Agent header for API requests.
+    /// </summary>
+    public string? ClientName { get; set; }
+
     public string? Model { get; set; }
 
     /// <summary>
@@ -874,6 +882,7 @@ protected ResumeSessionConfig(ResumeSessionConfig? other)
         if (other is null) return;
 
         AvailableTools = other.AvailableTools is not null ? [.. other.AvailableTools] : null;
+        ClientName = other.ClientName;
         ConfigDir = other.ConfigDir;
         CustomAgents = other.CustomAgents is not null ? [.. other.CustomAgents] : null;
         DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
@@ -896,6 +905,12 @@ protected ResumeSessionConfig(ResumeSessionConfig? other)
         WorkingDirectory = other.WorkingDirectory;
     }
 
+    /// <summary>
+    /// Client name to identify the application using the SDK.
+    /// Included in the User-Agent header for API requests.
+    /// </summary>
+    public string? ClientName { get; set; }
+
     /// <summary>
     /// Model to use for this session. Can change the model when resuming.
     /// </summary>

go/client.go

@@ -455,6 +455,7 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 	if config != nil {
 		req.Model = config.Model
 		req.SessionID = config.SessionID
+		req.ClientName = config.ClientName
 		req.ReasoningEffort = config.ReasoningEffort
 		req.ConfigDir = config.ConfigDir
 		req.Tools = config.Tools
@@ -552,6 +553,7 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 	var req resumeSessionRequest
 	req.SessionID = sessionID
 	if config != nil {
+		req.ClientName = config.ClientName
 		req.Model = config.Model
 		req.ReasoningEffort = config.ReasoningEffort
 		req.SystemMessage = config.SystemMessage

go/types.go

@@ -330,6 +330,9 @@ type InfiniteSessionConfig struct {
 type SessionConfig struct {
 	// SessionID is an optional custom session ID
 	SessionID string
+	// ClientName identifies the application using the SDK.
+	// Included in the User-Agent header for API requests.
+	ClientName string
 	// Model to use for this session
 	Model string
 	// ReasoningEffort level for models that support it.
@@ -409,6 +412,9 @@ type ToolResult struct {
 
 // ResumeSessionConfig configures options when resuming a session
 type ResumeSessionConfig struct {
+	// ClientName identifies the application using the SDK.
+	// Included in the User-Agent header for API requests.
+	ClientName string
 	// Model to use for this session. Can change the model when resuming.
 	Model string
 	// Tools exposes caller-implemented tools to the CLI
@@ -626,6 +632,7 @@ type permissionRequestResponse struct {
 type createSessionRequest struct {
 	Model             string                     `json:"model,omitempty"`
 	SessionID         string                     `json:"sessionId,omitempty"`
+	ClientName        string                     `json:"clientName,omitempty"`
 	ReasoningEffort   string                     `json:"reasoningEffort,omitempty"`
 	Tools             []Tool                     `json:"tools,omitempty"`
 	SystemMessage     *SystemMessageConfig       `json:"systemMessage,omitempty"`
@@ -655,6 +662,7 @@ type createSessionResponse struct {
 // resumeSessionRequest is the request for session.resume
 type resumeSessionRequest struct {
 	SessionID         string                     `json:"sessionId"`
+	ClientName        string                     `json:"clientName,omitempty"`
 	Model             string                     `json:"model,omitempty"`
 	ReasoningEffort   string                     `json:"reasoningEffort,omitempty"`
 	Tools             []Tool                     `json:"tools,omitempty"`

nodejs/src/client.ts

@@ -513,6 +513,7 @@ export class CopilotClient {
         const response = await this.connection!.sendRequest("session.create", {
             model: config.model,
             sessionId: config.sessionId,
+            clientName: config.clientName,
             reasoningEffort: config.reasoningEffort,
             tools: config.tools?.map((tool) => ({
                 name: tool.name,
@@ -594,6 +595,7 @@ export class CopilotClient {
 
         const response = await this.connection!.sendRequest("session.resume", {
             sessionId,
+            clientName: config.clientName,
             model: config.model,
             reasoningEffort: config.reasoningEffort,
             systemMessage: config.systemMessage,

nodejs/src/types.ts

@@ -615,6 +615,12 @@ export interface SessionConfig {
      */
     sessionId?: string;
 
+    /**
+     * Client name to identify the application using the SDK.
+     * Included in the User-Agent header for API requests.
+     */
+    clientName?: string;
+
     /**
      * Model to use for this session
      */
@@ -730,6 +736,7 @@ export interface SessionConfig {
  */
 export type ResumeSessionConfig = Pick<
     SessionConfig,
+    | "clientName"
     | "model"
     | "tools"
     | "systemMessage"

python/copilot/client.py

@@ -467,6 +467,8 @@ async def create_session(self, config: Optional[SessionConfig] = None) -> Copilo
             payload["model"] = cfg["model"]
         if cfg.get("session_id"):
             payload["sessionId"] = cfg["session_id"]
+        if cfg.get("client_name"):
+            payload["clientName"] = cfg["client_name"]
         if cfg.get("reasoning_effort"):
             payload["reasoningEffort"] = cfg["reasoning_effort"]
         if tool_defs:
@@ -629,6 +631,11 @@ async def resume_session(
 
         payload: dict[str, Any] = {"sessionId": session_id}
 
+        # Add client name if provided
+        client_name = cfg.get("client_name")
+        if client_name:
+            payload["clientName"] = client_name
+
         # Add model if provided
         model = cfg.get("model")
         if model:

python/copilot/types.py

@@ -462,6 +462,9 @@ class SessionConfig(TypedDict, total=False):
     """Configuration for creating a session"""
 
     session_id: str  # Optional custom session ID
+    # Client name to identify the application using the SDK.
+    # Included in the User-Agent header for API requests.
+    client_name: str
     model: str  # Model to use for this session. Use client.list_models() to see available models.
     # Reasoning effort level for models that support it.
     # Only valid for models where capabilities.supports.reasoning_effort is True.
@@ -529,6 +532,8 @@ class ProviderConfig(TypedDict, total=False):
 class ResumeSessionConfig(TypedDict, total=False):
     """Configuration for resuming a session"""
 
+    # Client name to identify the application using the SDK.
+    client_name: str
     # Model to use for this session. Can change the model when resuming.
     model: str
     tools: list[Tool]