Switching sessions is instant, sticks, and never stops the one you left
A picked session appears at once, a late reload no longer pulls you back, and a working session keeps working when you leave it.
Picking a session used to wait for the engine before anything changed, and with the wall on, a reload already under way could select the session you had just left.
Now the session you pick paints from its saved transcript straight away while the engine catches up, and only your newest pick counts.
Moving to another session also no longer stops the one you left. It keeps working, and you can watch it on the wall or come back to it. Stop still stops.