Codex will integrate GPT-5.6 Ultra OpenAI's core product lead has confirmed that GPT-5.6 Ultra will be added to Codex. Previously, users urged OpenAI to bring GPT-5.6 into Codex, pointing out that Codex's higher usage limits have made the Claude Max 20x subscription less appealing. Sottiaux directly responded, 'Ultra will be in codex,' but the specific launch date has not been disclosed.