fix: correct Windows CLI detection for npm-installed tools

The CLI managers for Claude Code, Gemini CLI, Codex CLI, and Qwen CLI
were incorrectly searching for `.exe` files on Windows. These tools are
installed via npm which creates `.cmd` wrapper scripts, not `.exe` files.

The fix removes the explicit `.exe` extension check because `shutil.which()`
automatically handles Windows PATHEXT environment variable, which includes
`.CMD`, `.BAT`, `.EXE`, and other executable extensions.

Before: `shutil.which("claude.exe")` -> None (not found)
After:  `shutil.which("claude")` -> finds claude.cmd via PATHEXT

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Kirill Turanskiy

src/mcpm/clients/managers/claude_code.py

@@ -42,8 +42,8 @@ def is_client_installed(self) -> bool:
         Returns:
             bool: True if claude command is available, False otherwise
         """
-        claude_executable = "claude.exe" if self._system == "Windows" else "claude"
-        return shutil.which(claude_executable) is not None
+        # shutil.which() handles Windows PATHEXT automatically (.cmd, .bat, .exe, etc.)
+        return shutil.which("claude") is not None
 
     def get_client_info(self) -> Dict[str, str]:
         """Get information about this client

src/mcpm/clients/managers/codex_cli.py

@@ -47,8 +47,8 @@ def is_client_installed(self) -> bool:
         Returns:
             bool: True if codex command is available, False otherwise
         """
-        codex_executable = "codex.exe" if self._system == "Windows" else "codex"
-        return shutil.which(codex_executable) is not None
+        # shutil.which() handles Windows PATHEXT automatically (.cmd, .bat, .exe, etc.)
+        return shutil.which("codex") is not None
 
     def get_client_info(self) -> Dict[str, str]:
         """Get information about this client

src/mcpm/clients/managers/gemini_cli.py

@@ -49,8 +49,8 @@ def is_client_installed(self) -> bool:
         Returns:
             bool: True if gemini command is available, False otherwise
         """
-        gemini_executable = "gemini.exe" if self._system == "Windows" else "gemini"
-        return shutil.which(gemini_executable) is not None
+        # shutil.which() handles Windows PATHEXT automatically (.cmd, .bat, .exe, etc.)
+        return shutil.which("gemini") is not None
 
     def get_client_info(self) -> Dict[str, str]:
         """Get information about this client

src/mcpm/clients/managers/qwen_cli.py

@@ -44,8 +44,8 @@ def is_client_installed(self) -> bool:
         Returns:
             bool: True if qwen command is available, False otherwise
         """
-        qwen_executable = "qwen.exe" if self._system == "Windows" else "qwen"
-        return shutil.which(qwen_executable) is not None
+        # shutil.which() handles Windows PATHEXT automatically (.cmd, .bat, .exe, etc.)
+        return shutil.which("qwen") is not None
 
     def get_client_info(self) -> Dict[str, str]:
         """Get information about this client

tests/test_clients/test_qwen_cli.py

@@ -37,44 +37,48 @@ def test_qwen_cli_manager_get_empty_config():
 def test_qwen_cli_manager_is_client_installed():
     """Test QwenCliManager is_client_installed method"""
     manager = QwenCliManager()
-    
+
     # Mock shutil.which to return a path (simulating installed client)
     with patch("shutil.which", return_value="/usr/local/bin/qwen") as mock_which:
         assert manager.is_client_installed() is True
         mock_which.assert_called_with("qwen")
-    
+
     # Mock shutil.which to return None (simulating uninstalled client)
     with patch("shutil.which", return_value=None) as mock_which:
         assert manager.is_client_installed() is False
         mock_which.assert_called_with("qwen")
 
 
 def test_qwen_cli_manager_is_client_installed_windows():
-    """Test QwenCliManager is_client_installed method on Windows"""
+    """Test QwenCliManager is_client_installed method on Windows
+
+    Note: shutil.which() handles Windows PATHEXT automatically, so we always
+    search for "qwen" without extension. This finds qwen.cmd, qwen.ps1, qwen.exe, etc.
+    """
     manager = QwenCliManager()
-    
+
     with patch.object(manager, "_system", "Windows"):
-        # Mock shutil.which to return a path (simulating installed client)
-        with patch("shutil.which", return_value="C:\\Program Files\\qwen\\qwen.exe") as mock_which:
+        # Mock shutil.which to return a path (simulating installed client via npm .cmd)
+        with patch("shutil.which", return_value="C:\\Users\\user\\AppData\\Roaming\\npm\\qwen.cmd") as mock_which:
             assert manager.is_client_installed() is True
-            mock_which.assert_called_with("qwen.exe")
-        
+            mock_which.assert_called_with("qwen")  # No .exe - shutil.which handles PATHEXT
+
         # Mock shutil.which to return None (simulating uninstalled client)
         with patch("shutil.which", return_value=None) as mock_which:
             assert manager.is_client_installed() is False
-            mock_which.assert_called_with("qwen.exe")
+            mock_which.assert_called_with("qwen")
 
 
 def test_qwen_cli_manager_get_empty_config_structure():
     """Test QwenCliManager _get_empty_config method returns expected structure"""
     manager = QwenCliManager()
     config = manager._get_empty_config()
-    
+
     # Check that required keys are present
     assert "mcpServers" in config
     assert "theme" in config
     assert "selectedAuthType" in config
-    
+
     # Check default values
     assert config["mcpServers"] == {}
     assert config["theme"] == "Qwen Dark"
@@ -88,4 +92,4 @@ def test_qwen_cli_manager_get_client_info():
     assert info["name"] == "Qwen CLI"
     assert info["download_url"] == "https://github.com/QwenLM/qwen-code"
     assert info["config_file"] == os.path.expanduser("~/.qwen/settings.json")
-    assert info["description"] == "Alibaba's Qwen CLI tool"
+    assert info["description"] == "Alibaba's Qwen CLI tool"