Unset/empty url still maps to durable user-data chat.db. Explicit :memory: is not rewritten; CLI warns when not quiet. DatabaseConfig.url default is None; engine treats None as memory.
Mark PTY master FD non-inheritable; run read_pty/close_pty via to_thread; close_all PTY sessions on chat exit. Add --log-level; clearer invalid TOML errors. Keep export/status free of provider secrets.