Expose enableConfigDiscovery in all SDK languages

dotnet/src/Client.cs

@@ -502,6 +502,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 config.CustomAgents,
                 config.Agent,
                 config.ConfigDir,
+                config.EnableConfigDiscovery,
                 config.SkillDirectories,
                 config.DisabledSkills,
                 config.InfiniteSessions,
@@ -618,6 +619,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 hasHooks ? true : null,
                 config.WorkingDirectory,
                 config.ConfigDir,
+                config.EnableConfigDiscovery,
                 config.DisableResume is true ? true : null,
                 config.Streaming is true ? true : null,
                 config.McpServers,
@@ -1640,6 +1642,7 @@ internal record CreateSessionRequest(
         List<CustomAgentConfig>? CustomAgents,
         string? Agent,
         string? ConfigDir,
+        bool? EnableConfigDiscovery,
         List<string>? SkillDirectories,
         List<string>? DisabledSkills,
         InfiniteSessionConfig? InfiniteSessions,
@@ -1686,6 +1689,7 @@ internal record ResumeSessionRequest(
         bool? Hooks,
         string? WorkingDirectory,
         string? ConfigDir,
+        bool? EnableConfigDiscovery,
         bool? DisableResume,
         bool? Streaming,
         Dictionary<string, object>? McpServers,

dotnet/src/Types.cs

@@ -1603,6 +1603,7 @@ protected SessionConfig(SessionConfig? other)
         CustomAgents = other.CustomAgents is not null ? [.. other.CustomAgents] : null;
         Agent = other.Agent;
         DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
+        EnableConfigDiscovery = other.EnableConfigDiscovery;
         ExcludedTools = other.ExcludedTools is not null ? [.. other.ExcludedTools] : null;
         Hooks = other.Hooks;
         InfiniteSessions = other.InfiniteSessions;
@@ -1660,6 +1661,19 @@ protected SessionConfig(SessionConfig? other)
     /// </summary>
     public string? ConfigDir { get; set; }
 
+    /// <summary>
+    /// When <see langword="true"/>, automatically discovers MCP server configurations
+    /// (e.g. <c>.mcp.json</c>, <c>.vscode/mcp.json</c>) and skill directories from
+    /// the working directory and merges them with any explicitly provided
+    /// <see cref="McpServers"/> and <see cref="SkillDirectories"/>, with explicit
+    /// values taking precedence on name collision.
+    /// <para>
+    /// Custom instruction files (<c>.github/copilot-instructions.md</c>, <c>AGENTS.md</c>, etc.)
+    /// are always loaded from the working directory regardless of this setting.
+    /// </para>
+    /// </summary>
+    public bool? EnableConfigDiscovery { get; set; }
+
     /// <summary>
     /// Custom tool functions available to the language model during the session.
     /// </summary>
@@ -1817,6 +1831,7 @@ protected ResumeSessionConfig(ResumeSessionConfig? other)
         Agent = other.Agent;
         DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
         DisableResume = other.DisableResume;
+        EnableConfigDiscovery = other.EnableConfigDiscovery;
         ExcludedTools = other.ExcludedTools is not null ? [.. other.ExcludedTools] : null;
         Hooks = other.Hooks;
         InfiniteSessions = other.InfiniteSessions;
@@ -1929,6 +1944,19 @@ protected ResumeSessionConfig(ResumeSessionConfig? other)
     /// </summary>
     public string? ConfigDir { get; set; }
 
+    /// <summary>
+    /// When <see langword="true"/>, automatically discovers MCP server configurations
+    /// (e.g. <c>.mcp.json</c>, <c>.vscode/mcp.json</c>) and skill directories from
+    /// the working directory and merges them with any explicitly provided
+    /// <see cref="McpServers"/> and <see cref="SkillDirectories"/>, with explicit
+    /// values taking precedence on name collision.
+    /// <para>
+    /// Custom instruction files (<c>.github/copilot-instructions.md</c>, <c>AGENTS.md</c>, etc.)
+    /// are always loaded from the working directory regardless of this setting.
+    /// </para>
+    /// </summary>
+    public bool? EnableConfigDiscovery { get; set; }
+
     /// <summary>
     /// When true, the session.resume event is not emitted.
     /// Default: false (resume event is emitted).

go/client.go

@@ -578,6 +578,9 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 	req.ClientName = config.ClientName
 	req.ReasoningEffort = config.ReasoningEffort
 	req.ConfigDir = config.ConfigDir
+	if config.EnableConfigDiscovery {
+		req.EnableConfigDiscovery = Bool(true)
+	}
 	req.Tools = config.Tools
 	wireSystemMessage, transformCallbacks := extractTransformCallbacks(config.SystemMessage)
 	req.SystemMessage = wireSystemMessage
@@ -754,6 +757,9 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 	}
 	req.WorkingDirectory = config.WorkingDirectory
 	req.ConfigDir = config.ConfigDir
+	if config.EnableConfigDiscovery {
+		req.EnableConfigDiscovery = Bool(true)
+	}
 	if config.DisableResume {
 		req.DisableResume = Bool(true)
 	}

go/types.go

@@ -465,6 +465,13 @@ type SessionConfig struct {
 	// ConfigDir overrides the default configuration directory location.
 	// When specified, the session will use this directory for storing config and state.
 	ConfigDir string
+	// EnableConfigDiscovery, when true, automatically discovers MCP server configurations
+	// (e.g. .mcp.json, .vscode/mcp.json) and skill directories from the working directory
+	// and merges them with any explicitly provided MCPServers and SkillDirectories, with
+	// explicit values taking precedence on name collision.
+	// Custom instruction files (.github/copilot-instructions.md, AGENTS.md, etc.) are
+	// always loaded from the working directory regardless of this setting.
+	EnableConfigDiscovery bool
 	// Tools exposes caller-implemented tools to the CLI
 	Tools []Tool
 	// SystemMessage configures system message customization
@@ -692,6 +699,13 @@ type ResumeSessionConfig struct {
 	WorkingDirectory string
 	// ConfigDir overrides the default configuration directory location.
 	ConfigDir string
+	// EnableConfigDiscovery, when true, automatically discovers MCP server configurations
+	// (e.g. .mcp.json, .vscode/mcp.json) and skill directories from the working directory
+	// and merges them with any explicitly provided MCPServers and SkillDirectories, with
+	// explicit values taking precedence on name collision.
+	// Custom instruction files (.github/copilot-instructions.md, AGENTS.md, etc.) are
+	// always loaded from the working directory regardless of this setting.
+	EnableConfigDiscovery bool
 	// Streaming enables streaming of assistant message and reasoning chunks.
 	// When true, assistant.message_delta and assistant.reasoning_delta events
 	// with deltaContent are sent as the response is generated.
@@ -909,6 +923,7 @@ type createSessionRequest struct {
 	CustomAgents       []CustomAgentConfig            `json:"customAgents,omitempty"`
 	Agent              string                         `json:"agent,omitempty"`
 	ConfigDir          string                         `json:"configDir,omitempty"`
+	EnableConfigDiscovery *bool                       `json:"enableConfigDiscovery,omitempty"`
 	SkillDirectories   []string                       `json:"skillDirectories,omitempty"`
 	DisabledSkills     []string                       `json:"disabledSkills,omitempty"`
 	InfiniteSessions   *InfiniteSessionConfig         `json:"infiniteSessions,omitempty"`
@@ -948,6 +963,7 @@ type resumeSessionRequest struct {
 	Hooks              *bool                          `json:"hooks,omitempty"`
 	WorkingDirectory   string                         `json:"workingDirectory,omitempty"`
 	ConfigDir          string                         `json:"configDir,omitempty"`
+	EnableConfigDiscovery *bool                       `json:"enableConfigDiscovery,omitempty"`
 	DisableResume      *bool                          `json:"disableResume,omitempty"`
 	Streaming          *bool                          `json:"streaming,omitempty"`
 	MCPServers         map[string]MCPServerConfig     `json:"mcpServers,omitempty"`

nodejs/src/client.ts

@@ -742,6 +742,7 @@ export class CopilotClient {
                 customAgents: config.customAgents,
                 agent: config.agent,
                 configDir: config.configDir,
+                enableConfigDiscovery: config.enableConfigDiscovery,
                 skillDirectories: config.skillDirectories,
                 disabledSkills: config.disabledSkills,
                 infiniteSessions: config.infiniteSessions,
@@ -873,6 +874,7 @@ export class CopilotClient {
                 hooks: !!(config.hooks && Object.values(config.hooks).some(Boolean)),
                 workingDirectory: config.workingDirectory,
                 configDir: config.configDir,
+                enableConfigDiscovery: config.enableConfigDiscovery,
                 streaming: config.streaming,
                 mcpServers: config.mcpServers,
                 envValueMode: "direct",

nodejs/src/types.ts

@@ -1074,6 +1074,19 @@ export interface SessionConfig {
      */
     configDir?: string;
 
+    /**
+     * When true, automatically discovers MCP server configurations (e.g. `.mcp.json`,
+     * `.vscode/mcp.json`) and skill directories from the working directory and merges
+     * them with any explicitly provided `mcpServers` and `skillDirectories`, with
+     * explicit values taking precedence on name collision.
+     *
+     * Note: custom instruction files (`.github/copilot-instructions.md`, `AGENTS.md`, etc.)
+     * are always loaded from the working directory regardless of this setting.
+     *
+     * @default false
+     */
+    enableConfigDiscovery?: boolean;
+
     /**
      * Tools exposed to the CLI server
      */
@@ -1226,6 +1239,7 @@ export type ResumeSessionConfig = Pick<
     | "hooks"
     | "workingDirectory"
     | "configDir"
+    | "enableConfigDiscovery"
     | "mcpServers"
     | "customAgents"
     | "agent"

python/copilot/client.py

@@ -1202,6 +1202,7 @@ async def create_session(
         custom_agents: list[CustomAgentConfig] | None = None,
         agent: str | None = None,
         config_dir: str | None = None,
+        enable_config_discovery: bool | None = None,
         skill_directories: list[str] | None = None,
         disabled_skills: list[str] | None = None,
         infinite_sessions: InfiniteSessionConfig | None = None,
@@ -1238,6 +1239,13 @@ async def create_session(
             custom_agents: Custom agent configurations.
             agent: Agent to use for the session.
             config_dir: Override for the configuration directory.
+            enable_config_discovery: When True, automatically discovers MCP server
+                configurations (e.g. ``.mcp.json``, ``.vscode/mcp.json``) and skill
+                directories from the working directory and merges them with any
+                explicitly provided ``mcp_servers`` and ``skill_directories``, with
+                explicit values taking precedence on name collision. Custom instruction
+                files (``.github/copilot-instructions.md``, ``AGENTS.md``, etc.) are
+                always loaded regardless of this setting.
             skill_directories: Directories to search for skills.
             disabled_skills: Skills to disable.
             infinite_sessions: Infinite session configuration.
@@ -1362,6 +1370,10 @@ async def create_session(
         if config_dir:
             payload["configDir"] = config_dir
 
+        # Add config discovery flag if provided
+        if enable_config_discovery is not None:
+            payload["enableConfigDiscovery"] = enable_config_discovery
+
         # Add skill directories configuration if provided
         if skill_directories:
             payload["skillDirectories"] = skill_directories
@@ -1455,6 +1467,7 @@ async def resume_session(
         custom_agents: list[CustomAgentConfig] | None = None,
         agent: str | None = None,
         config_dir: str | None = None,
+        enable_config_discovery: bool | None = None,
         skill_directories: list[str] | None = None,
         disabled_skills: list[str] | None = None,
         infinite_sessions: InfiniteSessionConfig | None = None,
@@ -1491,6 +1504,13 @@ async def resume_session(
             custom_agents: Custom agent configurations.
             agent: Agent to use for the session.
             config_dir: Override for the configuration directory.
+            enable_config_discovery: When True, automatically discovers MCP server
+                configurations (e.g. ``.mcp.json``, ``.vscode/mcp.json``) and skill
+                directories from the working directory and merges them with any
+                explicitly provided ``mcp_servers`` and ``skill_directories``, with
+                explicit values taking precedence on name collision. Custom instruction
+                files (``.github/copilot-instructions.md``, ``AGENTS.md``, etc.) are
+                always loaded regardless of this setting.
             skill_directories: Directories to search for skills.
             disabled_skills: Skills to disable.
             infinite_sessions: Infinite session configuration.
@@ -1588,6 +1608,8 @@ async def resume_session(
             payload["workingDirectory"] = working_directory
         if config_dir:
             payload["configDir"] = config_dir
+        if enable_config_discovery is not None:
+            payload["enableConfigDiscovery"] = enable_config_discovery
 
         # TODO: disable_resume is not a keyword arg yet; keeping for future use
         if mcp_servers: