Add fallback to taskkill /T before using WMI

Try taskkill /T first as it's simpler and works in many cases.
Only fall back to the recursive WMI approach if taskkill /T fails.
This provides better compatibility across different Windows environments.

Reported-by: fweinberger

Author: felixweinberger

src/mcp/client/stdio/__init__.py

@@ -257,11 +257,25 @@ async def _kill_process_tree_windows(pid: int) -> None:
     Recursively kill a process and all its children on Windows.
     Uses WMI to find child processes since taskkill /T doesn't always work.
     """
+    # First try taskkill with /T flag
+    result = await anyio.to_thread.run_sync(
+        subprocess.run,
+        ["taskkill", "/F", "/T", "/PID", str(pid)],
+        capture_output=True,
+        shell=False,
+        check=False,
+    )
+    
+    # If that worked, we're done
+    if result.returncode == 0:
+        return
+    
+    # Otherwise, try to find and kill children manually
     # First, get all child processes
-    children_pids = set()
+    children_pids: set[int] = set()
 
     # Use wmic to get child processes
-    result = await anyio.to_thread.run_sync(
+    wmic_result = await anyio.to_thread.run_sync(
         subprocess.run,
         ["wmic", "process", "where", f"ParentProcessId={pid}", "get", "ProcessId", "/FORMAT:VALUE"],
         capture_output=True,
@@ -270,9 +284,9 @@ async def _kill_process_tree_windows(pid: int) -> None:
         text=True,
     )
 
-    if result.returncode == 0 and result.stdout:
+    if wmic_result.returncode == 0 and wmic_result.stdout:
         # Parse child PIDs
-        for line in result.stdout.strip().split('\n'):
+        for line in wmic_result.stdout.strip().split('\n'):
             if line.startswith('ProcessId='):
                 try:
                     child_pid = int(line.split('=')[1].strip())