Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper
Summary
A detailed migration guide from Claude Opus to GPT-5.6 Sol for a production AI agent that builds and edits websites. It reports performance improvements (2.2x faster, 27% cheaper) and walks through a three-step process: fix the eval harness, adjust tool schemas and caching, and make reasoning replay self-contained. The article also shares insights on model-specific behaviors and the importance of proper prompt caching for cost efficiency.