GPT 5.5: A New Architecture That Breaks Old Prompts
GPT 5.5 is not a post-training update. It's a new base model with new architecture, new pretraining corpus, and new agent-oriented objectives, co-designed with Nvidia on 100,000 Blackwell GPUs. Your GPT 5.4 prompts will not work the same way. Switching models will break your workflows.
