This was the week of Claude Opus 4.6, and also of ChatGPT-5.3-Codex. Both leading models got substantial upgrades, although OpenAI's is confined to Codex. Once again, the frontier of AI got more advanced, especially for agentic coding but also for everything else.

I spent the week so far covering Opus, with two posts devoted to the extensive model card, and then one giving benchmarks, reactions, capabilities and a synthesis, which functions as the central review.

We also got GLM-5, Seedance 2.0, Claude fast mode, an app for Codex and much more.

Claude fast mode means you can pay a premium to get faster replies from Opus 4.6. It's very much not cheap, but it can be worth every penny. More on that in the next agentic coding update.

One of the most frustrating things about AI is the constant goalpost moving, both in terms of capability and safety. People say ‘oh [X] would be a huge deal but is a crazy sci-fi concept’ or ‘[Y] will never happen’ or ‘surely we would not be so stupid as to [Z]’ and then [X], [Y] and [Z] all happen and everyone shrugs as if nothing happened and [...]