On Thursday, OpenAI released GPT-5.4, a new foundation model billed as “our most capable and efficient frontier model for professional work.” In addition to the standard version, GPT-5.4 is also available as a reasoning model (GPT-5.4 Thinking) or optimized for high performance (GPT-5.4 Pro). The API version of the model will be available with context windows as large as 1 million tokens, by far the largest context window available from OpenAI. OpenAI also emphasized improved token efficiency, s...