Tried Gemini 2 weeks ago to see where it's at, with gemini-cli.

Failed to use tools, failed to follow instructions, and then went into deranged loop mode.

Essentially, it's where it was 1.5 years ago when I tried it the last time.

It's honestly unbelievable how Google managed to fail so miserably at this.

Their harness might be behind

I think failures that I observed with gemini are unrelated to the harness. Because the same failures happened with third party harnesses too.

It’s great on AI Studio. Harness issues, I agree.

I have not experienced any issues with Gemini 3.1 Pro.

Agree, I never actually had great success with Opus. I think its the failures that are annoying, its probably better than codex when its "good", but it fails in annoying ways that I think codex very seldom does.

I wouldn't call codex considerably better. It may depend on specific codebase and your expectations, but codex produces more "abstraction for the sake of abstraction" even on simple tasks, while opus in my experience usually chooses right level of abstraction for given task.