> And then there's the fact Fable is barely usable because it randomly downgrades to Opus out of nowhere whenever it thinks about exploits.

I suspect it's not what you meant, but it's definitely not random and is very deliberate. Just today I got it to reliably trigger the "safety" filter with (drumroll) having it list the weight keys of a 300M parameter ModernBERT-derived model. Their "safety" classifier must be matching one of the key names in there and trigger their "this is a frontier model" anti-competitive filter[1] (even though it's just a tiny 300M parameter model, four orders of magnitude smaller than the frontier).

[1]: https://news.ycombinator.com/item?id=48464732

Fortunately once you know how it works (i.e. dumb keyword classifier) it's easy-ish to get around: just rename the keys so that it doesn't contain the naughty keyword. (At least as long as it doesn't trigger on something in its own thinking trace, which needs... more creative workarounds.)