Introducing GPT-5.4 mini and nano

OpenAI released GPT-5.4 mini and nano on March 17, 2026 for coding and subagents; mini runs over 2x faster than GPT-5 mini. In the API, mini has a 400k context window and costs $0.75/$4.50 per 1M input/output tokens, while nano is API-only at $0.20/$1.25. The key signal is performance per latency: mini scores 54.4% on SWE-Bench Pro versus GPT-5.4 at 57.7%.

Why it matters: This is an official OpenAI model launch, not a routine patch. It includes concrete numbers—>2x speed, 400k context, API pricing, and 54.4% vs 57.7% on SWE-Bench Pro—so HKR-H/K/R all pass; scored at the low end of the 85–94 band.