Codex Skill Guide

Name: codex
Rating: 76
Author: ericpardee

Running a Task

•
If unclear, ask the user (via AskUserQuestion) what they want reviewed or changed.
•
Assemble the codex command with appropriate options:
- •-m, --model gpt-5.1-codex-max (default model)
- •--config model_reasoning_effort="<level>" where level is: none, minimal, low, medium, high, xhigh
- •--sandbox <mode> - use read-only for reviews, workspace-write for edits, danger-full-access for network/broad access
- •--full-auto - only for write operations, not needed for read-only
- •-C, --cd <DIR> - run from a different directory
•
When continuing a previous session, use resume syntax:
code
```
echo "your prompt here" | codex exec --skip-git-repo-check resume --last 2>/dev/null
```
Do not use configuration flags when resuming unless explicitly requested - the session inherits original settings.
•
IMPORTANT: Append 2>/dev/null to suppress thinking tokens (stderr). Only show stderr if debugging is needed.
•
Run the command, 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'."

Quick Reference

Use case	Command example
Code review	`codex exec -m gpt-5.1-codex-max --config model_reasoning_effort="xhigh" --sandbox read-only "Review the code..." 2>/dev/null`
Apply edits	`codex exec -m gpt-5.1-codex-max --config model_reasoning_effort="xhigh" --sandbox workspace-write --full-auto "Refactor..." 2>/dev/null`
Full access	`codex exec -m gpt-5.1-codex-max --sandbox danger-full-access --full-auto "..." 2>/dev/null`
Resume	`echo "continue with..." \| codex exec --skip-git-repo-check resume --last 2>/dev/null`
Different dir	`codex exec -C /path/to/dir --sandbox read-only "..." 2>/dev/null`

Following Up

•When output includes actionable findings or the user might want changes applied, offer to resume the session.
•When resuming, pipe the new prompt via stdin - the session keeps its original model, reasoning effort, and sandbox mode.

Auto-Fixing Critical Bugs in PR Reviews

When codex identifies HIGH severity bugs during PR reviews, automatically fix them without asking for permission:

•Identify severity: Parse codex output for "High" or "HIGH" severity bugs

•Auto-fix workflow:

bash

# Resume codex session with fix instructions
echo "Fix all HIGH severity bugs identified in the review. For each bug, apply the necessary code changes." | codex exec --skip-git-repo-check resume --last --sandbox workspace-write --full-auto 2>/dev/null

•Commit fixes: After codex applies fixes, commit with descriptive message
•Report: Tell user what was fixed

Severity guidelines:

•HIGH: Auto-fix (data loss, security holes, correctness bugs, broken functionality)
•MEDIUM: Ask user first (performance issues, tech debt, unclear impact)
•LOW: Report only (style suggestions, minor improvements)

Safety notes:

•Only auto-fix in review/PR context (not exploratory coding)
•Always commit fixes immediately after applying
•User can revert commits if needed
•If codex fix fails or is unclear, stop and ask user

Example:

code

Codex found: "High - Date constraints never reach Qdrant"
→ Automatically resume codex to fix
→ Commit: "Fix: Push date constraints to Qdrant query"
→ Report: "Fixed HIGH severity date filtering bug in query.py"

Error Handling

•Stop and report failures when codex exits non-zero; request direction before retrying.
•Before using --full-auto, --sandbox danger-full-access, or --skip-git-repo-check, ask for user permission unless already given.
•When output includes warnings or partial results, summarize and ask how to proceed.