258755a24f
Regression test for the ret=-2 / errmsg='unknown error' disambiguation: - ret=-2 or errcode=-2 with 'unknown error' → stale session (True) - ret=-2 with 'freq limit' or other errmsg → rate limit (False) - ret=-14 → not matched here (handled by SESSION_EXPIRED_ERRCODE path) - Success codes and missing errmsg → False