I believe the logic is to generate a SELL using the final day's CLOSE value which makes sense and is what I saw in the previous examples. What am I missing???
In the Quickstart guide examples there is no logic to close the position at the end of the backtest.
If you want to generate a sell specifically using the final day's close value, you can do so in the strategy's stop method
I didn't try this by myself, but based on the bt workflow I doubt that this will work, since stop is called after all the bars are gone and it should be no price to execute the order.