codex-companion

name	codex-companion
description	OpenAI Codex / GPT-5.4 integration for Claude Code. Use when the user says "consult with openai", "talk to codex", "ask gpt-5.4", "get a second opinion from openai", "delegate to codex", "openai review", or "codex rescue". Provides code reviews, adversarial reviews, rescue operations (when Claude is stuck), and GPT-5.4 task delegation with structured prompting. Runs the baked Codex CLI under the current profile; auth resolves from ~/.codex ([consultants.codex]) wired by the entrypoint. NOT for non-code tasks (research/content/design → dedicated skills), simple one-off edits Claude can finish alone, or DeepSeek reasoning (→ deepseek-reasoning). From openai/codex-plugin-cc.
version	1.0.0
author	OpenAI (adapted for Agentbox)
tags	["codex","openai","gpt-5.4","review","rescue","adversarial"]
env_vars	["OPENAI_API_KEY"]

Codex Companion

OpenAI's official Codex plugin for Claude Code, adapted for the Agentbox container. Delegates code review, adversarial review, and rescue tasks to GPT-5.4 via the Codex CLI.

When to Use This Skill

• Code review: Get a Codex review of your git changes (working tree or branch)
• Adversarial review: Challenge your implementation approach and design choices
• Rescue: When Claude is stuck, hand the task to Codex for a second opinion
• GPT-5.4 delegation: Offload substantial coding, debugging, or research tasks
• Cross-model validation: Use Codex as a check on Claude's work

When Not to Use

• For simple tasks Claude can finish quickly — don't add Codex overhead
• For non-code tasks (research, content, design) — use dedicated skills instead
• For DeepSeek reasoning — use deepseek-reasoning skill instead
• If OPENAI_API_KEY is not configured — run /codex:setup first

Container Integration

Codex runs under the current tmux profile — there is no separate pseudo-user (the openai-user/as-openai/UID-1002 model is retired). The baked Codex CLI reads its credentials from CODEX_HOME (~/.codex), where the entrypoint wires [consultants.codex] auth and the agentbox-memory MCP server on first boot. Set OPENAI_API_KEY in the environment only if you are overriding that baked auth.

# Codex commands run in-place; no user switch needed
/codex:review              # Review working tree changes
/codex:adversarial-review  # Challenge the implementation approach
/codex:rescue [task]       # Hand a stuck task to Codex
/codex:status              # Check Codex job status
/codex:result              # Get last Codex result
/codex:cancel              # Cancel running Codex job

Commands

Command	Description
/codex:review	Code review of git changes (working tree or branch)
/codex:adversarial-review	Challenge implementation, design choices, tradeoffs
/codex:rescue [task]	Delegate investigation or fix to Codex when stuck
/codex:status	Check Codex job progress
/codex:result	Retrieve last Codex output
/codex:cancel	Cancel running Codex job
/codex:setup	Configure Codex CLI and API key

Rescue Agent

The codex-rescue subagent activates proactively when:

• Claude Code is stuck on a debugging task
• A second implementation pass would help
• Deeper root-cause investigation is needed
• A substantial coding task should be delegated

The rescue agent uses this skill's bundled prompting reference library (skills/gpt-5-4-prompting/ — prompt blocks, recipes, and antipatterns) to compose tight, structured Codex prompts with XML tags, output contracts, and verification loops.

GPT-5.4 Prompting Patterns

The skill includes a reference library for composing effective Codex prompts:

Pattern	Use Case
<task> + <completeness_contract> + <verification_loop>	Coding / debugging
<task> + <grounding_rules> + <structured_output_contract>	Review tasks
<task> + <research_mode> + <citation_rules>	Research / recommendations
<task> + <action_safety>	Write-capable tasks (prevents unrelated refactors)

Review Output Schema

Reviews follow a structured JSON schema (review-output.schema.json) with:

• Severity levels (critical, major, minor, suggestion)
• Category classification (bug, security, performance, design, style)
• File + line references
• Confidence scores

Hooks

• SessionStart/SessionEnd: Lifecycle management for Codex companion state
• Stop: Review gate — optionally triggers a Codex review before session ends

Environment Variables

Variable	Required	Description
OPENAI_API_KEY	No	Optional override; auth normally resolves from ~/.codex ([consultants.codex]) wired by the entrypoint
CODEX_MODEL	No	Override model (default: GPT-5.4, spark maps to gpt-5.3-codex-spark)

Setup

# Auth is wired by the entrypoint (~/.codex / [consultants.codex]); no setup
# is normally needed. To (re)configure the Codex CLI or supply your own key:
/codex:setup

# Verify:
/codex:status

Integration with Other Skills

Skill	Relationship
openai-codex	Legacy MCP bridge — codex-companion is the full-featured replacement
build-with-quality	BWQ can delegate review phases to Codex for cross-model validation
github-code-review	Codex reviews complement Claude reviews for multi-perspective analysis
vanity-engineering-review	Run adversarial review first, then vanity check for over-engineering

Attribution

Codex Plugin for Claude Code by OpenAI. Apache 2.0 License.