feat: add mcpOAuthTokenStorage support across all SDKs

dotnet/src/Client.cs

@@ -616,6 +616,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 config.Streaming is true ? true : null,
                 config.IncludeSubAgentStreamingEvents,
                 config.McpServers,
+                config.McpOAuthTokenStorage ?? McpOAuthTokenStorageMode.InMemory,
                 "direct",
                 config.CustomAgents,
                 config.DefaultAgent,
@@ -780,6 +781,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 config.Streaming is true ? true : null,
                 config.IncludeSubAgentStreamingEvents,
                 config.McpServers,
+                config.McpOAuthTokenStorage ?? McpOAuthTokenStorageMode.InMemory,
                 "direct",
                 config.CustomAgents,
                 config.DefaultAgent,
@@ -1986,6 +1988,7 @@ internal record CreateSessionRequest(
         bool? Streaming,
         bool? IncludeSubAgentStreamingEvents,
         IDictionary<string, McpServerConfig>? McpServers,
+        McpOAuthTokenStorageMode? McpOAuthTokenStorage,
         string? EnvValueMode,
         IList<CustomAgentConfig>? CustomAgents,
         DefaultAgentConfig? DefaultAgent,
@@ -2050,6 +2053,7 @@ internal record ResumeSessionRequest(
         bool? Streaming,
         bool? IncludeSubAgentStreamingEvents,
         IDictionary<string, McpServerConfig>? McpServers,
+        McpOAuthTokenStorageMode? McpOAuthTokenStorage,
         string? EnvValueMode,
         IList<CustomAgentConfig>? CustomAgents,
         DefaultAgentConfig? DefaultAgent,
@@ -2139,6 +2143,7 @@ internal record PermissionRequestResponseV2(
     [JsonSerializable(typeof(ListSessionsResponse))]
     [JsonSerializable(typeof(GetSessionMetadataRequest))]
     [JsonSerializable(typeof(GetSessionMetadataResponse))]
+    [JsonSerializable(typeof(McpOAuthTokenStorageMode))]
     [JsonSerializable(typeof(ModelCapabilitiesOverride))]
     [JsonSerializable(typeof(PermissionRequestResult))]
     [JsonSerializable(typeof(PermissionRequestResultKind))]

dotnet/src/Types.cs

@@ -1804,6 +1804,21 @@ public enum McpHttpServerConfigOauthGrantType
     ClientCredentials
 }
 
+/// <summary>
+/// Controls how MCP OAuth tokens are stored for a session.
+/// </summary>
+[JsonConverter(typeof(JsonStringEnumConverter<McpOAuthTokenStorageMode>))]
+public enum McpOAuthTokenStorageMode
+{
+    /// <summary>Tokens are stored in the OS keychain, shared across sessions.</summary>
+    [JsonStringEnumMemberName("persistent")]
+    Persistent,
+
+    /// <summary>Tokens are stored in memory and discarded when the session ends.</summary>
+    [JsonStringEnumMemberName("in-memory")]
+    InMemory
+}
+
 /// <summary>
 /// Abstract base class for MCP server configurations.
 /// </summary>
@@ -2085,6 +2100,7 @@ protected SessionConfig(SessionConfig? other)
                 ? new Dictionary<string, McpServerConfig>(dict, dict.Comparer)
                 : new Dictionary<string, McpServerConfig>(other.McpServers))
             : null;
+        McpOAuthTokenStorage = other.McpOAuthTokenStorage;
         Model = other.Model;
         ModelCapabilities = other.ModelCapabilities;
         OnAutoModeSwitch = other.OnAutoModeSwitch;
@@ -2261,6 +2277,12 @@ protected SessionConfig(SessionConfig? other)
     /// </summary>
     public IDictionary<string, McpServerConfig>? McpServers { get; set; }
 
+    /// <summary>
+    /// Controls how MCP OAuth tokens are stored for this session.
+    /// Default: <see cref="McpOAuthTokenStorageMode.InMemory"/> for safe multitenant behavior.
+    /// </summary>
+    public McpOAuthTokenStorageMode? McpOAuthTokenStorage { get; set; }
+
     /// <summary>
     /// Custom agent configurations for the session.
     /// </summary>
@@ -2394,6 +2416,7 @@ protected ResumeSessionConfig(ResumeSessionConfig? other)
                 ? new Dictionary<string, McpServerConfig>(dict, dict.Comparer)
                 : new Dictionary<string, McpServerConfig>(other.McpServers))
             : null;
+        McpOAuthTokenStorage = other.McpOAuthTokenStorage;
         Model = other.Model;
         ModelCapabilities = other.ModelCapabilities;
         OnAutoModeSwitch = other.OnAutoModeSwitch;
@@ -2587,6 +2610,12 @@ protected ResumeSessionConfig(ResumeSessionConfig? other)
     /// </summary>
     public IDictionary<string, McpServerConfig>? McpServers { get; set; }
 
+    /// <summary>
+    /// Controls how MCP OAuth tokens are stored for this session.
+    /// Default: <see cref="McpOAuthTokenStorageMode.InMemory"/> for safe multitenant behavior.
+    /// </summary>
+    public McpOAuthTokenStorageMode? McpOAuthTokenStorage { get; set; }
+
     /// <summary>
     /// Custom agent configurations for the session.
     /// </summary>

dotnet/test/Unit/CloneTests.cs

@@ -94,6 +94,7 @@ public void SessionConfig_Clone_CopiesAllProperties()
             EnableSessionTelemetry = false,
             IncludeSubAgentStreamingEvents = false,
             McpServers = new Dictionary<string, McpServerConfig> { ["server1"] = new McpStdioServerConfig { Command = "echo" } },
+            McpOAuthTokenStorage = McpOAuthTokenStorageMode.Persistent,
             CustomAgents = [new CustomAgentConfig { Name = "agent1", Model = "claude-haiku-4.5" }],
             Agent = "agent1",
             Cloud = new CloudSessionOptions
@@ -127,6 +128,7 @@ public void SessionConfig_Clone_CopiesAllProperties()
         Assert.Equal(original.EnableSessionTelemetry, clone.EnableSessionTelemetry);
         Assert.Equal(original.IncludeSubAgentStreamingEvents, clone.IncludeSubAgentStreamingEvents);
         Assert.Equal(original.McpServers.Count, clone.McpServers!.Count);
+        Assert.Equal(original.McpOAuthTokenStorage, clone.McpOAuthTokenStorage);
         Assert.Equal(original.CustomAgents.Count, clone.CustomAgents!.Count);
         Assert.Equal(original.CustomAgents[0].Model, clone.CustomAgents[0].Model);
         Assert.Equal(original.Agent, clone.Agent);

go/client.go

@@ -636,6 +636,11 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 	req.ModelCapabilities = config.ModelCapabilities
 	req.WorkingDirectory = config.WorkingDirectory
 	req.MCPServers = config.MCPServers
+	if config.MCPOAuthTokenStorage != "" {
+		req.MCPOAuthTokenStorage = config.MCPOAuthTokenStorage
+	} else {
+		req.MCPOAuthTokenStorage = "in-memory"
+	}
 	req.EnvValueMode = "direct"
 	req.CustomAgents = config.CustomAgents
 	req.DefaultAgent = config.DefaultAgent
@@ -841,6 +846,11 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 		req.ContinuePendingWork = Bool(true)
 	}
 	req.MCPServers = config.MCPServers
+	if config.MCPOAuthTokenStorage != "" {
+		req.MCPOAuthTokenStorage = config.MCPOAuthTokenStorage
+	} else {
+		req.MCPOAuthTokenStorage = "in-memory"
+	}
 	req.EnvValueMode = "direct"
 	req.CustomAgents = config.CustomAgents
 	req.DefaultAgent = config.DefaultAgent

go/client_test.go

@@ -615,6 +615,60 @@ func TestResumeSessionRequest_InstructionDirectories(t *testing.T) {
 	})
 }
 
+func TestCreateSessionRequest_MCPOAuthTokenStorage(t *testing.T) {
+	t.Run("includes mcpOAuthTokenStorage in JSON when set", func(t *testing.T) {
+		req := createSessionRequest{MCPOAuthTokenStorage: "in-memory"}
+		data, err := json.Marshal(req)
+		if err != nil {
+			t.Fatalf("Failed to marshal: %v", err)
+		}
+		var m map[string]any
+		if err := json.Unmarshal(data, &m); err != nil {
+			t.Fatalf("Failed to unmarshal: %v", err)
+		}
+		if m["mcpOAuthTokenStorage"] != "in-memory" {
+			t.Errorf("Expected mcpOAuthTokenStorage to be 'in-memory', got %v", m["mcpOAuthTokenStorage"])
+		}
+	})
+
+	t.Run("omits mcpOAuthTokenStorage from JSON when empty", func(t *testing.T) {
+		req := createSessionRequest{}
+		data, _ := json.Marshal(req)
+		var m map[string]any
+		json.Unmarshal(data, &m)
+		if _, ok := m["mcpOAuthTokenStorage"]; ok {
+			t.Error("Expected mcpOAuthTokenStorage to be omitted when empty")
+		}
+	})
+}
+
+func TestResumeSessionRequest_MCPOAuthTokenStorage(t *testing.T) {
+	t.Run("includes mcpOAuthTokenStorage in JSON when set", func(t *testing.T) {
+		req := resumeSessionRequest{SessionID: "s1", MCPOAuthTokenStorage: "persistent"}
+		data, err := json.Marshal(req)
+		if err != nil {
+			t.Fatalf("Failed to marshal: %v", err)
+		}
+		var m map[string]any
+		if err := json.Unmarshal(data, &m); err != nil {
+			t.Fatalf("Failed to unmarshal: %v", err)
+		}
+		if m["mcpOAuthTokenStorage"] != "persistent" {
+			t.Errorf("Expected mcpOAuthTokenStorage to be 'persistent', got %v", m["mcpOAuthTokenStorage"])
+		}
+	})
+
+	t.Run("omits mcpOAuthTokenStorage from JSON when empty", func(t *testing.T) {
+		req := resumeSessionRequest{SessionID: "s1"}
+		data, _ := json.Marshal(req)
+		var m map[string]any
+		json.Unmarshal(data, &m)
+		if _, ok := m["mcpOAuthTokenStorage"]; ok {
+			t.Error("Expected mcpOAuthTokenStorage to be omitted when empty")
+		}
+	})
+}
+
 func TestOverridesBuiltInTool(t *testing.T) {
 	t.Run("OverridesBuiltInTool is serialized in tool definition", func(t *testing.T) {
 		tool := Tool{

go/types.go

@@ -658,6 +658,11 @@ type SessionConfig struct {
 	ModelCapabilities *rpc.ModelCapabilitiesOverride
 	// MCPServers configures MCP servers for the session
 	MCPServers map[string]MCPServerConfig
+	// MCPOAuthTokenStorage controls how MCP OAuth tokens are stored for this session.
+	// "persistent" stores tokens in the OS keychain (shared across sessions).
+	// "in-memory" stores tokens in memory and discards them when the session ends.
+	// Defaults to "in-memory" for safe multitenant behavior.
+	MCPOAuthTokenStorage string
 	// CustomAgents configures custom agents for the session
 	CustomAgents []CustomAgentConfig
 	// DefaultAgent configures the default agent (the built-in agent that handles turns when no custom agent is selected).
@@ -902,6 +907,11 @@ type ResumeSessionConfig struct {
 	IncludeSubAgentStreamingEvents *bool
 	// MCPServers configures MCP servers for the session
 	MCPServers map[string]MCPServerConfig
+	// MCPOAuthTokenStorage controls how MCP OAuth tokens are stored for this session.
+	// "persistent" stores tokens in the OS keychain (shared across sessions).
+	// "in-memory" stores tokens in memory and discards them when the session ends.
+	// Defaults to "in-memory" for safe multitenant behavior.
+	MCPOAuthTokenStorage string
 	// CustomAgents configures custom agents for the session
 	CustomAgents []CustomAgentConfig
 	// DefaultAgent configures the default agent (the built-in agent that handles turns when no custom agent is selected).
@@ -1162,6 +1172,7 @@ type createSessionRequest struct {
 	Streaming                      *bool                          `json:"streaming,omitempty"`
 	IncludeSubAgentStreamingEvents *bool                          `json:"includeSubAgentStreamingEvents,omitempty"`
 	MCPServers                     map[string]MCPServerConfig     `json:"mcpServers,omitempty"`
+	MCPOAuthTokenStorage           string                         `json:"mcpOAuthTokenStorage,omitempty"`
 	EnvValueMode                   string                         `json:"envValueMode,omitempty"`
 	CustomAgents                   []CustomAgentConfig            `json:"customAgents,omitempty"`
 	DefaultAgent                   *DefaultAgentConfig            `json:"defaultAgent,omitempty"`
@@ -1220,6 +1231,7 @@ type resumeSessionRequest struct {
 	Streaming                      *bool                          `json:"streaming,omitempty"`
 	IncludeSubAgentStreamingEvents *bool                          `json:"includeSubAgentStreamingEvents,omitempty"`
 	MCPServers                     map[string]MCPServerConfig     `json:"mcpServers,omitempty"`
+	MCPOAuthTokenStorage           string                         `json:"mcpOAuthTokenStorage,omitempty"`
 	EnvValueMode                   string                         `json:"envValueMode,omitempty"`
 	CustomAgents                   []CustomAgentConfig            `json:"customAgents,omitempty"`
 	DefaultAgent                   *DefaultAgentConfig            `json:"defaultAgent,omitempty"`

nodejs/src/client.ts

@@ -824,6 +824,7 @@ export class CopilotClient {
                 streaming: config.streaming,
                 includeSubAgentStreamingEvents: config.includeSubAgentStreamingEvents ?? true,
                 mcpServers: config.mcpServers,
+                mcpOAuthTokenStorage: config.mcpOAuthTokenStorage ?? "in-memory",
                 envValueMode: "direct",
                 customAgents: config.customAgents,
                 defaultAgent: config.defaultAgent,
@@ -981,6 +982,7 @@ export class CopilotClient {
                 streaming: config.streaming,
                 includeSubAgentStreamingEvents: config.includeSubAgentStreamingEvents ?? true,
                 mcpServers: config.mcpServers,
+                mcpOAuthTokenStorage: config.mcpOAuthTokenStorage ?? "in-memory",
                 envValueMode: "direct",
                 customAgents: config.customAgents,
                 defaultAgent: config.defaultAgent,

nodejs/src/types.ts

@@ -1444,6 +1444,15 @@ export interface SessionConfig {
      */
     includeSubAgentStreamingEvents?: boolean;
 
+    /**
+     * Controls how MCP OAuth tokens are stored for this session.
+     * - `"persistent"` — tokens are stored in the OS keychain (shared across sessions)
+     * - `"in-memory"` — tokens are stored in memory and discarded when the session ends
+     *
+     * @default "in-memory"
+     */
+    mcpOAuthTokenStorage?: "persistent" | "in-memory";
+
     /**
      * MCP server configurations for the session.
      * Keys are server names, values are server configurations.
@@ -1567,6 +1576,7 @@ export type ResumeSessionConfig = Pick<
     | "customAgents"
     | "defaultAgent"
     | "agent"
+    | "mcpOAuthTokenStorage"
     | "skillDirectories"
     | "instructionDirectories"
     | "disabledSkills"

python/copilot/client.py

@@ -1340,6 +1340,7 @@ async def create_session(
         streaming: bool | None = None,
         include_sub_agent_streaming_events: bool | None = None,
         mcp_servers: dict[str, MCPServerConfig] | None = None,
+        mcp_oauth_token_storage: Literal["persistent", "in-memory"] | None = None,
         custom_agents: list[CustomAgentConfig] | None = None,
         default_agent: DefaultAgentConfig | dict[str, Any] | None = None,
         agent: str | None = None,
@@ -1402,6 +1403,10 @@ async def create_session(
                 ``agentId`` set). When False, only non-streaming sub-agent events and
                 ``subagent.*`` lifecycle events are forwarded. Defaults to True.
             mcp_servers: MCP server configurations.
+            mcp_oauth_token_storage: Controls how MCP OAuth tokens are stored.
+                ``"persistent"`` uses the OS keychain (shared across sessions).
+                ``"in-memory"`` stores tokens in memory (discarded on session end).
+                Defaults to ``"in-memory"`` for safe multitenant behavior.
             custom_agents: Custom agent configurations.
             default_agent: Configuration for the default agent,
                 including tool visibility controls.
@@ -1551,6 +1556,8 @@ async def create_session(
         # Add MCP servers configuration if provided
         if mcp_servers:
             payload["mcpServers"] = mcp_servers
+        # Default MCP OAuth token storage to in-memory for safe multitenant behavior
+        payload["mcpOAuthTokenStorage"] = mcp_oauth_token_storage or "in-memory"
         payload["envValueMode"] = "direct"
 
         # Add custom agents configuration if provided
@@ -1713,6 +1720,7 @@ async def resume_session(
         streaming: bool | None = None,
         include_sub_agent_streaming_events: bool | None = None,
         mcp_servers: dict[str, MCPServerConfig] | None = None,
+        mcp_oauth_token_storage: Literal["persistent", "in-memory"] | None = None,
         custom_agents: list[CustomAgentConfig] | None = None,
         default_agent: DefaultAgentConfig | dict[str, Any] | None = None,
         agent: str | None = None,
@@ -1775,6 +1783,10 @@ async def resume_session(
                 ``agentId`` set). When False, only non-streaming sub-agent events and
                 ``subagent.*`` lifecycle events are forwarded. Defaults to True.
             mcp_servers: MCP server configurations.
+            mcp_oauth_token_storage: Controls how MCP OAuth tokens are stored.
+                ``"persistent"`` uses the OS keychain (shared across sessions).
+                ``"in-memory"`` stores tokens in memory (discarded on session end).
+                Defaults to ``"in-memory"`` for safe multitenant behavior.
             custom_agents: Custom agent configurations.
             default_agent: Configuration for the default agent,
                 including tool visibility controls.
@@ -1918,6 +1930,8 @@ async def resume_session(
         # TODO: disable_resume is not a keyword arg yet; keeping for future use
         if mcp_servers:
             payload["mcpServers"] = mcp_servers
+        # Default MCP OAuth token storage to in-memory for safe multitenant behavior
+        payload["mcpOAuthTokenStorage"] = mcp_oauth_token_storage or "in-memory"
         payload["envValueMode"] = "direct"
 
         if custom_agents:

python/copilot/session.py

@@ -947,6 +947,11 @@ class SessionConfig(TypedDict, total=False):
     include_sub_agent_streaming_events: bool
     # MCP server configurations for the session
     mcp_servers: dict[str, MCPServerConfig]
+    # Controls how MCP OAuth tokens are stored for this session.
+    # "persistent" stores tokens in the OS keychain (shared across sessions).
+    # "in-memory" stores tokens in memory, discarded when the session ends.
+    # Defaults to "in-memory" for safe multitenant behavior.
+    mcp_oauth_token_storage: Literal["persistent", "in-memory"]
     # Custom agent configurations for the session
     custom_agents: list[CustomAgentConfig]
     # Configuration for the default agent.
@@ -1034,6 +1039,11 @@ class ResumeSessionConfig(TypedDict, total=False):
     include_sub_agent_streaming_events: bool
     # MCP server configurations for the session
     mcp_servers: dict[str, MCPServerConfig]
+    # Controls how MCP OAuth tokens are stored for this session.
+    # "persistent" stores tokens in the OS keychain (shared across sessions).
+    # "in-memory" stores tokens in memory, discarded when the session ends.
+    # Defaults to "in-memory" for safe multitenant behavior.
+    mcp_oauth_token_storage: Literal["persistent", "in-memory"]
     # Custom agent configurations for the session
     custom_agents: list[CustomAgentConfig]
     # Configuration for the default agent.