Fix MCP env vars: send envValueMode direct across all SDKs

dotnet/src/Client.cs

@@ -383,6 +383,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig? config = nul
             config?.WorkingDirectory,
             config?.Streaming == true ? true : null,
             config?.McpServers,
+            "direct",
             config?.CustomAgents,
             config?.ConfigDir,
             config?.SkillDirectories,
@@ -468,6 +469,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
             config?.DisableResume == true ? true : null,
             config?.Streaming == true ? true : null,
             config?.McpServers,
+            "direct",
             config?.CustomAgents,
             config?.SkillDirectories,
             config?.DisabledSkills,
@@ -1385,6 +1387,7 @@ internal record CreateSessionRequest(
         string? WorkingDirectory,
         bool? Streaming,
         Dictionary<string, object>? McpServers,
+        string? EnvValueMode,
         List<CustomAgentConfig>? CustomAgents,
         string? ConfigDir,
         List<string>? SkillDirectories,
@@ -1421,6 +1424,7 @@ internal record ResumeSessionRequest(
         bool? DisableResume,
         bool? Streaming,
         Dictionary<string, object>? McpServers,
+        string? EnvValueMode,
         List<CustomAgentConfig>? CustomAgents,
         List<string>? SkillDirectories,
         List<string>? DisabledSkills,

dotnet/test/Harness/E2ETestContext.cs

@@ -92,6 +92,7 @@ public IReadOnlyDictionary<string, string> GetEnvironment()
     public CopilotClient CreateClient() => new(new CopilotClientOptions
     {
         Cwd = WorkDir,
+        CliPath = GetCliPath(_repoRoot),
         Environment = GetEnvironment(),
         GithubToken = !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("CI")) ? "fake-token-for-e2e-tests" : null,
     });

dotnet/test/McpAndAgentsTests.cs

@@ -260,6 +260,41 @@ public async Task Should_Handle_Multiple_Custom_Agents()
         await session.DisposeAsync();
     }
 
+    [Fact]
+    public async Task Should_Pass_Literal_Env_Values_To_Mcp_Server_Subprocess()
+    {
+        var testHarnessDir = FindTestHarnessDir();
+        var mcpServers = new Dictionary<string, object>
+        {
+            ["env-echo"] = new McpLocalServerConfig
+            {
+                Type = "local",
+                Command = "node",
+                Args = [Path.Combine(testHarnessDir, "test-mcp-server.mjs")],
+                Env = new Dictionary<string, string> { ["TEST_SECRET"] = "hunter2" },
+                Cwd = testHarnessDir,
+                Tools = ["*"]
+            }
+        };
+
+        var session = await Client.CreateSessionAsync(new SessionConfig
+        {
+            McpServers = mcpServers
+        });
+
+        Assert.Matches(@"^[a-f0-9-]+$", session.SessionId);
+
+        var message = await session.SendAndWaitAsync(new MessageOptions
+        {
+            Prompt = "Use the env-echo/get_env tool to read the TEST_SECRET environment variable. Reply with just the value, nothing else."
+        });
+
+        Assert.NotNull(message);
+        Assert.Contains("hunter2", message!.Data.Content);
+
+        await session.DisposeAsync();
+    }
+
     [Fact]
     public async Task Should_Accept_Both_MCP_Servers_And_Custom_Agents()
     {
@@ -301,4 +336,17 @@ public async Task Should_Accept_Both_MCP_Servers_And_Custom_Agents()
 
         await session.DisposeAsync();
     }
+
+    private static string FindTestHarnessDir()
+    {
+        var dir = new DirectoryInfo(AppContext.BaseDirectory);
+        while (dir != null)
+        {
+            var candidate = Path.Combine(dir.FullName, "test", "harness", "test-mcp-server.mjs");
+            if (File.Exists(candidate))
+                return Path.GetDirectoryName(candidate)!;
+            dir = dir.Parent;
+        }
+        throw new InvalidOperationException("Could not find test/harness/test-mcp-server.mjs");
+    }
 }

go/client.go

@@ -464,6 +464,7 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 		req.Provider = config.Provider
 		req.WorkingDirectory = config.WorkingDirectory
 		req.MCPServers = config.MCPServers
+		req.EnvValueMode = "direct"
 		req.CustomAgents = config.CustomAgents
 		req.SkillDirectories = config.SkillDirectories
 		req.DisabledSkills = config.DisabledSkills
@@ -581,6 +582,7 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 			req.DisableResume = Bool(true)
 		}
 		req.MCPServers = config.MCPServers
+		req.EnvValueMode = "direct"
 		req.CustomAgents = config.CustomAgents
 		req.SkillDirectories = config.SkillDirectories
 		req.DisabledSkills = config.DisabledSkills

go/internal/e2e/mcp_and_agents_test.go

@@ -1,6 +1,7 @@
 package e2e
 
 import (
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -104,6 +105,51 @@ func TestMCPServers(t *testing.T) {
 		session2.Destroy()
 	})
 
+	t.Run("should pass literal env values to MCP server subprocess", func(t *testing.T) {
+		ctx.ConfigureForTest(t)
+
+		mcpServerPath, err := filepath.Abs("../../../test/harness/test-mcp-server.mjs")
+		if err != nil {
+			t.Fatalf("Failed to resolve test-mcp-server path: %v", err)
+		}
+		mcpServerDir := filepath.Dir(mcpServerPath)
+
+		mcpServers := map[string]copilot.MCPServerConfig{
+			"env-echo": {
+				"type":    "local",
+				"command": "node",
+				"args":    []string{mcpServerPath},
+				"tools":   []string{"*"},
+				"env":     map[string]string{"TEST_SECRET": "hunter2"},
+				"cwd":     mcpServerDir,
+			},
+		}
+
+		session, err := client.CreateSession(t.Context(), &copilot.SessionConfig{
+			MCPServers: mcpServers,
+		})
+		if err != nil {
+			t.Fatalf("Failed to create session: %v", err)
+		}
+
+		if session.SessionID == "" {
+			t.Error("Expected non-empty session ID")
+		}
+
+		message, err := session.SendAndWait(t.Context(), copilot.MessageOptions{
+			Prompt: "Use the env-echo/get_env tool to read the TEST_SECRET environment variable. Reply with just the value, nothing else.",
+		})
+		if err != nil {
+			t.Fatalf("Failed to send message: %v", err)
+		}
+
+		if message.Data.Content == nil || !strings.Contains(*message.Data.Content, "hunter2") {
+			t.Errorf("Expected message to contain 'hunter2', got: %v", message.Data.Content)
+		}
+
+		session.Destroy()
+	})
+
 	t.Run("handle multiple MCP servers", func(t *testing.T) {
 		ctx.ConfigureForTest(t)
 

go/types.go

@@ -638,6 +638,7 @@ type createSessionRequest struct {
 	WorkingDirectory  string                     `json:"workingDirectory,omitempty"`
 	Streaming         *bool                      `json:"streaming,omitempty"`
 	MCPServers        map[string]MCPServerConfig `json:"mcpServers,omitempty"`
+	EnvValueMode      string                     `json:"envValueMode,omitempty"`
 	CustomAgents      []CustomAgentConfig        `json:"customAgents,omitempty"`
 	ConfigDir         string                     `json:"configDir,omitempty"`
 	SkillDirectories  []string                   `json:"skillDirectories,omitempty"`
@@ -669,6 +670,7 @@ type resumeSessionRequest struct {
 	DisableResume     *bool                      `json:"disableResume,omitempty"`
 	Streaming         *bool                      `json:"streaming,omitempty"`
 	MCPServers        map[string]MCPServerConfig `json:"mcpServers,omitempty"`
+	EnvValueMode      string                     `json:"envValueMode,omitempty"`
 	CustomAgents      []CustomAgentConfig        `json:"customAgents,omitempty"`
 	SkillDirectories  []string                   `json:"skillDirectories,omitempty"`
 	DisabledSkills    []string                   `json:"disabledSkills,omitempty"`

nodejs/package.json

@@ -40,7 +40,7 @@
   "author": "GitHub",
   "license": "MIT",
   "dependencies": {
-    "@github/copilot": "^0.0.411-0",
+    "@github/copilot": "^0.0.411-1",
     "vscode-jsonrpc": "^8.2.1",
     "zod": "^4.3.6"
   },

nodejs/src/client.ts

@@ -34,11 +34,11 @@ import type {
     ModelInfo,
     ResumeSessionConfig,
     SessionConfig,
+    SessionContext,
     SessionEvent,
     SessionLifecycleEvent,
     SessionLifecycleEventType,
     SessionLifecycleHandler,
-    SessionContext,
     SessionListFilter,
     SessionMetadata,
     Tool,
@@ -529,6 +529,7 @@ export class CopilotClient {
             workingDirectory: config.workingDirectory,
             streaming: config.streaming,
             mcpServers: config.mcpServers,
+            envValueMode: "direct",
             customAgents: config.customAgents,
             configDir: config.configDir,
             skillDirectories: config.skillDirectories,
@@ -611,6 +612,7 @@ export class CopilotClient {
             configDir: config.configDir,
             streaming: config.streaming,
             mcpServers: config.mcpServers,
+            envValueMode: "direct",
             customAgents: config.customAgents,
             skillDirectories: config.skillDirectories,
             disabledSkills: config.disabledSkills,

nodejs/test/e2e/harness/sdkTestContext.ts

@@ -19,7 +19,7 @@ const SNAPSHOTS_DIR = resolve(__dirname, "../../../../test/snapshots");
 
 export async function createSdkTestContext({
     logLevel,
-}: { logLevel?: "error" | "none" | "warning" | "info" | "debug" | "all" } = {}) {
+}: { logLevel?: "error" | "none" | "warning" | "info" | "debug" | "all"; cliPath?: string } = {}) {
     const homeDir = realpathSync(fs.mkdtempSync(join(os.tmpdir(), "copilot-test-config-")));
     const workDir = realpathSync(fs.mkdtempSync(join(os.tmpdir(), "copilot-test-work-")));
 
@@ -40,6 +40,7 @@ export async function createSdkTestContext({
         cwd: workDir,
         env,
         logLevel: logLevel || "error",
+        cliPath: process.env.COPILOT_CLI_PATH,
         // Use fake token in CI to allow cached responses without real auth
         githubToken: process.env.CI === "true" ? "fake-token-for-e2e-tests" : undefined,
     });