You can do a lot better efficiency-wise if you control the source end-to-end though - you already group logically related changes into PRs, so you can save on scanning by asking the LLM to only look over the files you've changed. If you're touching security-relevant code, you can ask it for more per-file effort than the attacker might put into their own scanning. You can even do the big bulk scans an attacker might on a fixed schedule - each attacker has to run their own scan while you only need to run your one scan to find everything they would have. There's a massive cost asymmetry between the "hardening" phase for the defender and the "discovering exploits" phase for the attacker.

Exploitability also isn't binary: even if the attacker is better-resourced than you, they need to find a whole chain of exploits in your system, while you only need to break the weakest link in that chain.

If you boil security down to just a contest of who can burn more tokens, defenders get efficiency advantages only the best-resourced attackers can overcome. On net, public access to mythos-tier models will make software more secure.

I'm sure this approach breaks down at the very frontiers of highly technical fields but... virtually all work, even work by educated professionals, happens outside that area anyway. On well-trodden ground, you can improve at supervising agents by doing things that test your ability to supervise agents.

The defender also gets to make the first move by just putting a "run an agent to find vulns" step in their CI pipeline. If LLMs truly make finding exploits free, almost no LLM-findable exploits will ever make it into the codebase.

The only way break the equilibrium is still going to be a smart researcher capable of finding exploits that the commoditized tools alone can't.