I am doing novel work with codex but it does need some prompting ie. exploring possibilities from current codebase, adding papers to prompt etc.
For security, I think I generally start a new thread before committing to review from security pov.
If you are relying on the LLM and context, then unless your context is a secret your competitor is only ever one prompt behind you. If you're willing to pursue true novelty, you need a human and you can leap beyond your competition.
The reality is that a huge portion of my time is spent doing similar work and what LLMs largely do is pick up the smaller tasks or features that I may not have prioritized otherwise. Revolutionary in one sense, completely banal and a really minor part of my job in many others.
https://aisle.com/blog/what-ai-security-research-looks-like-...
LLMs also are quite bad for security. They can find simple bugs, but they don't find the really interesting ones that leverage "gap between mental model and implementation" or "combination of features and bugs" etc, which is where most of the interesting security work is imo.