| 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:review
/codex:adversarial-review
/codex:rescue [task]
/codex:status
/codex:result
/codex:cancel
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
/codex:setup
/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.
