AI models do not live and learn - it's worse. They actually get DUMMER if you don't start with a clean slate. This is important. One has to curate the context carefully.
I use codex daily and a moderately complex plan + a few files is more than enough context to make it blatantly ignore prompts like "stop and ask before adding new layers or data structures"
Is that context rot or model deficiency?
This is oversimplifying it. Read the metr report on the huggingface incident.