Codex Skill Guide

Running a Task

1. Ask the user (via AskUserQuestion) which model to run: gpt-5 or gpt-5-codex.
2. Ask the user (via AskUserQuestion) which reasoning effort to use: low, medium, or high.
3. Select the sandbox mode required for the task; default to --sandbox read-only unless edits or network access are necessary.
4. Assemble the command with the appropriate options:
   • -m, --model <MODEL>
   • --config model_reasoning_effort="<low|medium|high>"
   • --sandbox <read-only|workspace-write|danger-full-access>
   • --full-auto
   • -C, --cd <DIR>
   • --skip-git-repo-check
5. When continuing a previous session, use codex exec resume --last via stdin. IMPORTANT: When resuming, you CANNOT specify model, reasoning effort, or other flags—the session retains all settings from the original run. Resume syntax: echo "your prompt here" | codex exec resume --last
6. Run the command, capture stdout/stderr, and summarize the outcome for the user.