on_assignment_order_event() called before the shares are actually on the portfolio.

Expected Behavior

Assigned shares should be in portoflio when this method is called to correctly handle assignment (cannot liquidate open another strategy, etc), current behavior this would make Example #1 and #2 in the docs behave incorrectly: Examples: Options Models - Assignment

Actual Behavior

Shares are not in your portfolio before when on_assignment_order_event() is called.

Potential Solution

The only workaround right now to handle the a assigned position is to use a on_securities_changes, below is an example:

def on_order_event(self, order_event: OrderEvent) -> None:
    """Handle assignment by liquidating delivered shares."""
    if (order_event.symbol.security_type == SecurityType.EQUITY and
        order_event.status == OrderStatus.FILLED):
        self.liquidate(self._spy, tag="Assignment liquidation")

Reproducing the Problem

Here is a backtest replicating it: Test on_assignment_order_event()
It gets called before the shares are actually on the portfolio, printing the message:
2024-09-03 10:00:00 Quit(): Invested on assignment: False

Here is a backtest checking on_order_event to see the order the events arrive there:
Test on_order_event() order of event arrival on_assignment_order_event() does get called before on_order_event()

System Information

Cloud master branch.

Checklist

• [ X ] I have completely filled out this template
• [ X ] I have confirmed that this issue exists on the current master branch
• [ X ] I have confirmed that this is not a duplicate issue by searching issues

• I have provided detailed steps to reproduce the issue

Start with the assignment and order-event callback flow exercised by the linked backtests, then trace when assigned shares are added to the portfolio. Compare the callback order shown in the reproductions with the expected portfolio state. Done means on_assignment_order_event() observes the assigned shares before assignment handling runs, with the linked backtests or a regression test confirming the ordering.