fix: skip cmd.exe wrapping for MCP servers when Windows host connects to WSL

core/context/mcp/MCPConnection.ts

@@ -414,23 +414,30 @@ Org-level secrets can only be used for MCP by Background Agents (https://docs.co
   /**
    * Resolves the command and arguments for the current platform
    * On Windows, batch script commands need to be executed via cmd.exe
+   * UNLESS we're connected to a WSL remote (where Linux commands should run)
    * @param originalCommand The original command
    * @param originalArgs The original command arguments
    * @returns An object with the resolved command and arguments
    */
-  private resolveCommandForPlatform(
+  private async resolveCommandForPlatform(
     originalCommand: string,
     originalArgs: string[],
-  ): { command: string; args: string[] } {
-    // If not on Windows or not a batch command, return as-is
+  ): Promise<{ command: string; args: string[] }> {
+    // Check if we're on Windows host connected to WSL remote
+    const ideInfo = await this.extras?.ide?.getIdeInfo();
+    const isWindowsHostWithWslRemote =
+      process.platform === "win32" && ideInfo?.remoteName === "wsl";
+
+    // If not on Windows, or connected to WSL, or not a batch command, return as-is
     if (
       process.platform !== "win32" ||
+      isWindowsHostWithWslRemote ||
       !WINDOWS_BATCH_COMMANDS.includes(originalCommand)
     ) {
       return { command: originalCommand, args: originalArgs };
     }
 
-    // On Windows, we need to execute batch commands via cmd.exe
+    // On Windows (local), we need to execute batch commands via cmd.exe
     // Format: cmd.exe /c command [args]
     return {
       command: "cmd.exe",
@@ -569,7 +576,7 @@ Org-level secrets can only be used for MCP by Background Agents (https://docs.co
       }
     }
 
-    const { command, args } = this.resolveCommandForPlatform(
+    const { command, args } = await this.resolveCommandForPlatform(
       options.command,
       options.args || [],
     );

core/context/mcp/MCPConnection.vitest.ts

@@ -349,4 +349,101 @@ describe("MCPConnection", () => {
       }
     });
   });
+
+  describe("resolveCommandForPlatform", () => {
+    const baseOptions: InternalStdioMcpOptions = {
+      name: "test-mcp",
+      id: "test-id",
+      type: "stdio",
+      command: "npx",
+      args: ["-y", "@modelcontextprotocol/server-filesystem", "."],
+    };
+
+    it("should NOT wrap with cmd.exe when Windows host connects to WSL remote", async () => {
+      const mockIde = {
+        getIdeInfo: vi.fn().mockResolvedValue({ remoteName: "wsl" }),
+      } as any;
+
+      const conn = new MCPConnection(baseOptions, { ide: mockIde });
+
+      // Mock process.platform to be win32
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", { value: "win32" });
+
+      try {
+        const result = await (conn as any).resolveCommandForPlatform("npx", [
+          "-y",
+          "test",
+        ]);
+        // Should NOT wrap with cmd.exe when in WSL
+        expect(result.command).toBe("npx");
+        expect(result.args).toEqual(["-y", "test"]);
+      } finally {
+        Object.defineProperty(process, "platform", { value: originalPlatform });
+      }
+    });
+
+    it("should wrap with cmd.exe when Windows host is local (not WSL)", async () => {
+      const mockIde = {
+        getIdeInfo: vi.fn().mockResolvedValue({ remoteName: "" }),
+      } as any;
+
+      const conn = new MCPConnection(baseOptions, { ide: mockIde });
+
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", { value: "win32" });
+
+      try {
+        const result = await (conn as any).resolveCommandForPlatform("npx", [
+          "-y",
+          "test",
+        ]);
+        // Should wrap with cmd.exe for local Windows
+        expect(result.command).toBe("cmd.exe");
+        expect(result.args).toEqual(["/c", "npx", "-y", "test"]);
+      } finally {
+        Object.defineProperty(process, "platform", { value: originalPlatform });
+      }
+    });
+
+    it("should NOT wrap with cmd.exe on Linux regardless of batch command", async () => {
+      const conn = new MCPConnection(baseOptions);
+
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", { value: "linux" });
+
+      try {
+        const result = await (conn as any).resolveCommandForPlatform("npx", [
+          "-y",
+          "test",
+        ]);
+        expect(result.command).toBe("npx");
+        expect(result.args).toEqual(["-y", "test"]);
+      } finally {
+        Object.defineProperty(process, "platform", { value: originalPlatform });
+      }
+    });
+
+    it("should NOT wrap non-batch commands even on Windows", async () => {
+      const mockIde = {
+        getIdeInfo: vi.fn().mockResolvedValue({ remoteName: "" }),
+      } as any;
+
+      const conn = new MCPConnection(baseOptions, { ide: mockIde });
+
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", { value: "win32" });
+
+      try {
+        const result = await (conn as any).resolveCommandForPlatform("python", [
+          "script.py",
+        ]);
+        // python is not in WINDOWS_BATCH_COMMANDS, so no wrapping
+        expect(result.command).toBe("python");
+        expect(result.args).toEqual(["script.py"]);
+      } finally {
+        Object.defineProperty(process, "platform", { value: originalPlatform });
+      }
+    });
+  });
 });