# Albedo-owned MCP stdio launcher: no shell, scoped cwd, silent stderr. It
# stays the server's parent, in a process group of the server's own, so that
# closing its stdin ends the server even when the server ignores EOF: the
# server gets GRACE seconds, then SIGTERM, then SIGKILL of its whole group.
import os
import signal
import subprocess
import sys
import threading

GRACE = 2.0

_, cwd, command, *arguments = sys.argv
if cwd:
    os.environ["PWD"] = cwd
server = subprocess.Popen(
    [command, *arguments],
    executable=command,
    stdin=subprocess.PIPE,
    stderr=subprocess.DEVNULL,
    cwd=cwd or None,
    start_new_session=True,
)


def signal_group(sig):
    try:
        os.killpg(server.pid, sig)
    except (ProcessLookupError, PermissionError):
        pass


def exit_with_server():
    status = server.wait()
    # Whatever the server left running in its group goes with it.
    signal_group(signal.SIGKILL)
    os._exit(status if status >= 0 else 128 - status)


threading.Thread(target=exit_with_server, daemon=True).start()
assert server.stdin is not None
try:
    while chunk := os.read(0, 65536):
        server.stdin.write(chunk)
        server.stdin.flush()
except (BrokenPipeError, OSError):
    pass
try:
    server.stdin.close()
except BrokenPipeError:
    pass
for sig in (signal.SIGTERM, signal.SIGKILL):
    try:
        server.wait(GRACE)
        break
    except subprocess.TimeoutExpired:
        signal_group(sig)
server.wait()