OpenAI Codex Complete Plan Analysis: Agent Integration in the ChatGPT Ecosystem
Codex rides your ChatGPT subscription (Free / Go $8 / Plus $20 / Pro 5x $100 / Pro 20x $200), and since 2026/4/2 billing is token-based credits. The model line is GPT-5.6 Sol / Terra / Luna; GPT-5.4 and 5.4 mini retire from ChatGPT-signed-in Codex on 2026/8/31.