Codex subscriptions default to the best model your ChatGPT account offers
With a Codex subscription and no engine or model set, runs now use the top model on your ChatGPT account's own Codex model list, instead of always `openai-codex/gpt-5.6-sol`.
ChatGPT plans don't all offer the same Codex models. A free plan has no GPT-5.6 Sol, so until now every unconfigured task on one failed within seconds, and the ticket only said an internal error had occurred. We now check your account's model list with Codex once a day and pick its highest-ranked model that Sinatra supports. On plans that list newer models, that means your default moves off GPT-5.6 Sol too, for example to GPT-6 Astra. If Codex still turns a model down, the task stops and says your account doesn't offer it, and we check the list again. The message tells you whether replying will retry on another model your account offers, or whether you need to pick one. A model you chose yourself is never switched.
#1642