OpenAI quietly retired GPT-5.2 from ChatGPT and auto-migrated everyone to GPT-5.5.

As of June 12, OpenAI removed GPT-5.2 Instant, Thinking, and Pro, with existing conversations continuing on the matching GPT-5.5 variant. GPT-5.5 is now positioned as their strongest dedicated coding model. If you've got chat workflows tuned to 5.2 behavior, expect routing changes and re-test your prompts. Silent model swaps are exactly the kind of thing that breaks a finely-tuned prompt and gives you no error to debug.