``jarvis start`` spawned the server with ``start_new_session=True``. That is
POSIX-only — CPython's Windows ``_execute_child`` names the parameter
``unused_start_new_session`` and ignores it — so on Windows the server
inherited the launching console instead of detaching from it.
Closing that console, or logging off, therefore delivered CTRL_CLOSE_EVENT
to the server. Observed in the wild as the daemon dying overnight, with
forrtl: error (200): program aborting due to window-CLOSE event
in server.log (the Fortran runtime under NumPy handles the event and
aborts). ``jarvis start`` looked like it worked: it printed a PID, wrote the
pid file and exited 0, and the server ran for as long as the console stayed
open. Registered as a log-on scheduled task, this means the machine comes
back up with no backend.
Pass DETACHED_PROCESS on Windows so the child gets no console at all, plus
CREATE_NEW_PROCESS_GROUP so a Ctrl-C in the parent console cannot reach it.
POSIX keeps start_new_session.
Verified by attaching to each spawned process with AttachConsole():
start_new_session=True attaches successfully (the child shares a console);
DETACHED_PROCESS fails with ERROR_INVALID_HANDLE (no console exists).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
