When does the session close?
Positions are closed for you at 16:45 New York time and trading reopens at 18:00. The accounting day is cut at 17:00 Chicago time, which is the same instant.
You are flat by 16:45 New York time, Monday to Friday. Whatever is still open then is closed where it last printed, every working order is cancelled, and a ticket sent while the session is shut is refused. Trading reopens at 18:00 New York time, Sunday to Thursday.
Being flattened at the close is not a breach, here or at any firm that sells these accounts. The account carries on at the next open.
The close is read on the tape's clock, so it lands when your chart reaches 16:45 rather than ten minutes before it.
The accounting day rolls at 17:00 Chicago time, which is where your daily loss limit resets and where a new session opens on whatever equity the last one left behind. A session opens on where the previous one left the equity, never on where the account stands now, or a position carried across the roll would move its own daily floor overnight.
On a holiday with an early close Lucid has you flat before the market closes. That calendar is not here, so on those days the usual close applies.