Codex Skill Guide

Running a Task

Ask the user (via AskUserQuestion) which model to run: gpt-5.1 or gpt-5.1-codex or gpt-5.1-codex-max or gpt-5.1-mini.
Ask the user (via AskUserQuestion) which reasoning effort to use: low, medium, or high.
Select the sandbox mode required for the task; default to --sandbox read-only unless edits or network access are necessary.
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
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
Run the command, capture stdout/stderr, and summarize the outcome for the user.

Use case	Sandbox mode	Key flags
Read-only review or analysis	`read-only`	`--sandbox read-only`
Apply local edits	`workspace-write`	`--sandbox workspace-write --full-auto`
Permit network or broad access	`danger-full-access`	`--sandbox danger-full-access --full-auto`
Resume recent session	Inherited from original	`echo "prompt" \| codex exec resume --last` (no flags allowed)
Run from another directory	Match task needs	`-C <DIR>` plus other flags

After every codex command, immediately use AskUserQuestion to confirm next steps, collect clarifications, or decide whether to resume with codex exec resume --last.
When resuming, pipe the new prompt via stdin: echo "new prompt" | codex exec resume --last. The resumed session automatically uses the same model, reasoning effort, and sandbox mode from the original session.
Restate the chosen model, reasoning effort, and sandbox mode when proposing follow-up actions.

Stop and report failures whenever codex --version or a codex exec command exits non-zero; request direction before retrying.
Before you use high-impact flags (--full-auto, --sandbox danger-full-access, --skip-git-repo-check) ask the user for permission using AskUserQuestion unless it was already given.
When output includes warnings or partial results, summarize them and ask how to adjust using AskUserQuestion.