Codex Skill Guide

Name: codex
Rating: 76
Author: asgeo1

Running a Task

•
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> - specify model (optional, uses default if omitted)
- •--config model_reasoning_effort="<xhigh|high|medium|low>" - reasoning effort (optional)
- •--sandbox <read-only|workspace-write|danger-full-access> - sandbox mode
- •--full-auto - auto-approve within sandbox
- •-C, --cd <DIR> - working directory
- •--skip-git-repo-check - always use this flag
- •--json - output JSONL (use when you need to capture session ID)
•
IMPORTANT: By default, append 2>/dev/null to suppress thinking tokens (stderr). Only show stderr if debugging is needed.
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Run the command, capture stdout/stderr (filtered as appropriate), and summarize the outcome for the user.
•
After Codex completes, inform the user: "You can resume this Codex session at any time by saying 'codex resume' or asking me to continue."

Quick Reference

Use case	Key flags
Read-only review/analysis	`--sandbox read-only --skip-git-repo-check 2>/dev/null`
Apply local edits	`--sandbox workspace-write --full-auto --skip-git-repo-check 2>/dev/null`
Full access	`--sandbox danger-full-access --full-auto --skip-git-repo-check 2>/dev/null`
Resume latest session	`echo "prompt" \| codex exec --skip-git-repo-check resume --last 2>/dev/null`

Session Management

Resuming Latest Session

bash

echo "continue prompt" | codex exec --skip-git-repo-check resume --last 2>/dev/null

This works well for sequential execution (including subagent contexts).

Resuming with Explicit Session ID (Advanced)

If you need explicit session IDs (e.g., multiple parallel Codex sessions):

bash

# Get the most recent session ID from filesystem
SESSION_ID=$(ls -t ~/.codex/sessions/*/*/*/*.jsonl | head -1 | grep -oE '[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}')

# Resume with explicit ID
codex exec --skip-git-repo-check resume "$SESSION_ID" "continue prompt" 2>/dev/null

Following Up

•After every codex command, capture or note the session ID for potential resumption.
•When resuming, prefer explicit session IDs over --last for reliability.
•The resumed session automatically uses the same model, reasoning effort, and sandbox mode from the original session.
•Restate the chosen settings 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 using high-impact flags (--full-auto, --sandbox danger-full-access), ask the user for permission using AskUserQuestion unless already given.
•When output includes warnings or partial results, summarize them and ask how to adjust using AskUserQuestion.