Long chats start new work without rereading their whole history
Starting or checking a run in a long chat no longer rereads the chat's whole history from disk, so long chats stay quick.
Every time a run started or its state was looked up, Bandicot reread the chat's entire history file. In a long chat that is a lot of reading for a few lines. It now reads only the small index it already keeps, plus whatever was added since it last looked.