Codex, on the other hand, will follow something I said pages and pages ago, and because it has a much larger context window (at least with the setup I have here at work), it's just better at following orders.

This is important, but as a warning. At least in theory your agent will follow everything that it has in context, but LLMs rely on 'context compacting' when things get close to the limit. This means an LLM can and will drop your explicit instructions not to do things, and then happily do them because they're not in the context any more. You need to repeat important instructions.