A day-trading book shouldn't carry overnight. New 'eod' loop step calls
TradingExecutionService.close_session at TRADING_EOD_FLATTEN_TIME (default
15:55 ET): flattens every position (cancelling their bracket legs), cancels
resting entries, and blocks new entries for the rest of the session. Only fires
inside [flatten_time, 16:00) so a post-close restart doesn't queue useless
after-hours orders.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
