OpenAI GPT-5.5: The April 23, 2026 Agentic Model — What Actually Changes for Engineers?
Released April 23, 2026, GPT-5.5 scored 82.7% on Terminal-Bench 2.0 and 78.7% on OSWorld-Verified — outpacing Claude Opus 4.7 (69.4%) and Gemini 3.1 Pro (68.5%). It matches GPT-5.4 latency while using fewer tokens on Codex tasks. What changed behind the quiet launch, and what should engineering teams actually do?