Saved conversations keep their order under load

Every message in a saved assistant conversation carries a position, and that position is handed out one at a time so that two replies arriving at the same moment can never claim the same place in the thread. The mechanism was already right; what it was called was not.

The field behind it was named as though it counted the messages in a conversation. It never did — it hands out the next free position, and a message that fails to save after taking one leaves that number spent, exactly as it should. Anything that later read the name at face value would have been reading a number that drifts, and the first sign of it would have been a conversation displayed in the wrong order.

The field is now named for the job it does, and every existing conversation has been moved across so the messages already saved keep the positions they were written with. Nothing changes about what you see or do — this is a correction to the foundations, made while it was still free.