It is so stupid that Codex STILL does not include the current model in the system prompt. Your agent has no idea what it is beyond "based on GPT-6". I've complained about this for a year straight and they won't fix it for no good reason.
Developer slams Codex for omitting current model in system prompt
Developer theo criticizes Codex for still not stating the current model in its system prompt, leaving the agent knowing only it is "based on GPT-6". He has complained for a year with no fix.