I have Fable plan and Opus implement. I haven't had any major issues working this way; however, Opus does seem plain fucking stupid compared to what I experienced with Sonnet previously.

Weird how different people's experiences are. If it's making simple mistakes something must be wrong in your setup/context I assume? It's been solid for me, beyond the usual LLMisms that all models have. But I keep context pretty minimal.

> I'm dumbfounded to see Opus 5 making SO MANY mistakes in coding simple stuff.

To me it's not so much the dumb mistakes (although there are some of those) but the ultra-verbose, mega-inefficient "solutions" to some problems / prompts.

Stuff that "works" if you're the kind of person that considers slamming a semi-trailer at 200 mph into a door did, technically, result in the door being somehow "open".

As it's supposed to be one of the most advanced model, I can't help but wonder if the solutions are that bad/verbose/inefficient because we're already in a loop of models being trained on sloppy-pasta from previous models.