i haven't used any Anthropic models since Jan / Feb so i was excited to unleash fable on a bunch of benchmarks and a few of my most complicated repos. so far, it seems like a huge improvement over opus, especially for claude code expert use cases but still not on par with gpt 5.5 xhigh for my specific use cases. in fact, its pretty on par with my fine tuned k2.6 outside of the new claude code features . the areas where it seems to excel are large multi part reviews (it caught a handful of really subtle and complex bugs) and multi-step long running tasks. i kept it away from my research / training and infra code for obvious reasons, so this is 'normal' software dev specific .

overall, solid effort and a huge improvement over the most recent opus, but not pushing the frontier in any meaningful ways (at least that i can see so far). i will probably use it for the rest of the day just to be sure and then move back to 80% k2.6 and 20% gpt 5.5 xhigh