As the author of the now (in)famous report in https://github.com/anthropics/claude-code/issues/42796 issue (sorry stella :) all I can say is... sigh. Reading through the changelog felt as if they codified every bad experiment they ran that hurt Opus 4.6. It makes it clear that the degradation was not accidental.

I'm still sad. I had a transformative 6 months with Opus and do not regret it, but I'm also glad that I didn't let hope keep me stuck for another few weeks: had I been waiting for a correction I'd be crushed by this.

Hypothesis: Mythos maintains the behavior of what Opus used to be with a few tricks only now restricted to the hands of a few who Anthropic deems worthy. Opus is now the consumer line. I'll still use Opus for some code reviews, but it does not seem like it'll ever go back to collaborator status by-design. :(