We will see. As for "testing that could have been done before", Mozilla's posts indicate otherwise. Use of Opus 4.6 led to 22 security-sensitive bugs vs Mythos' 271 (https://blog.mozilla.org/en/privacy-security/ai-security-zer...). They already had the methodology in place when the more powerful model came along (https://hacks.mozilla.org/2026/05/behind-the-scenes-hardenin...):

> Once the end-to-end pipeline is in place, it’s trivial to swap in different models when they become available. Building this pipeline early helped us find a number of serious bugs using publicly-available models, and it also helped us hit the ground running when we had the opportunity to evaluate Claude Mythos Preview. In our experience, model upgrades increase the effectiveness of the entire pipeline: the system gets simultaneously better at finding potential bugs, creating proof-of-concept test cases to demonstrate them, and articulating their pathology and impact.