Function ssm_rollback_mode 

pub fn ssm_rollback_mode() -> SsmRollbackMode

The mode in force. Snapshot when nothing was published — mirroring the CLI’s explicit default for non-serve contexts (tests, examples), which never carry the flag. Production sizing/pool call sites take the mode as a PARAMETER and read this only at the outermost boundary, so unit tests never depend on the process-global cell.