Function default_dir 

pub fn default_dir() -> PathBuf

The default per-user credential directory, in precedence order: $AGENTD_CRED_DIR, else $XDG_STATE_HOME/agentd/creds, else $HOME/.local/state/agentd/creds, else the OS temp dir. The temp-dir fallback only applies to an environment with no HOME at all; the files written there are still 0600.