FWIW that's exactly what it does (updates the current state of the whole todo list each time). After two weeks of use I've never had it make a mistake in keeping track of my total list of tasks. By default (I mean I didn't ask it to do this) it outputs the total estimated time for each category of tasks, and that summation has been wrong (which wasn't that surprising to me, as "LLMs aren't great at math" is a known issue), but even then I just tell it "Can you double check the category totals?" and it fixes them.