codex

name	codex
description	Use when the user asks to run Codex CLI (codex exec, codex resume) or references OpenAI Codex for code analysis, refactoring, or automated editing

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.

Quick Reference

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

Following Up

• 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.

Error Handling

• 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.