Codex CLI - GPT-5.4

Second opinion, verification, analysis, code review, or autonomous task delegation using OpenAI's Codex CLI.

Defaults

Model: gpt-5.4 — always. Reasoning: xhigh — always, unless the user explicitly requests a different effort level.

ALWAYS pass them explicitly in commands — never rely on config.toml:

-m gpt-5.4 -c model_reasoning_effort="xhigh"

Override only when the user says so (e.g., "use low reasoning" → -c model_reasoning_effort="low").

Fast Mode

fast_mode is a stable feature flag (enabled by default). Uses service_tier = "fast" under the hood — same gpt-5.4 model, ~1.5x faster output, 2x credit cost. Only works with ChatGPT OAuth login (not API key).