I suspect it's not just this, there's plenty of 'optimization' around rubberbanding usage limits as well as routing to a different model in the backend. The incentives are too strong.

...the evidence, as best I can tell from the tweet, is that they asked Claude what effort level it was set to. But how would the model even know that?

Not convinced here.

Whatever Opus 5 is doing should not happen.

Prompt was "read and update the config file with new data". This work on 4.6 takes <2 minutes to read the file, parse the new data, and patch.

Opus 5 Result: 43 minutes of pulling containers, running sandboxes, creating testing suites, which included evaluating the entire repo beyond the scope of the config file.

Both: one file modification