Codex Agent

Codex Agent Collaboration Skill

This skill enables Claude Code to collaborate with OpenAI's Codex CLI agent.

MANDATORY: Code Review Workflow

IMPORTANT: When performing code review, you MUST follow this workflow:

Step 1: Call Codex for Review

codex exec -C <project_path> -s read-only -o /tmp/codex-review.md \
  "Review the code in <file_or_directory>. Check for:
   - Security vulnerabilities
   - Performance issues
   - Code quality and best practices
   - Potential bugs and edge cases
   - Naming and readability
   Provide specific, actionable feedback with file paths and line numbers."

Step 2: Read Codex Feedback

cat /tmp/codex-review.md

Step 3: Apply Fixes Based on Codex Feedback

For each issue identified by Codex:

1. Read the relevant file
2. Apply the fix using Edit tool
3. Verify the fix addresses Codex's concern

Step 4: Re-verify with Codex (Optional)

codex exec -C <project_path> -s read-only \
  "Verify the fixes applied to <files>. Confirm issues are resolved."

Workflow Examples

Example 1: Review and Fix a Single File

# Step 1: Get Codex review
codex exec -C /project -s read-only -o /tmp/codex-review.md \
  "Review src/auth/login.ts for security vulnerabilities and code quality issues. Provide specific line numbers and fixes."

# Step 2: Read the feedback
cat /tmp/codex-review.md

Then Claude reads the feedback, applies fixes with Edit tool, and optionally re-verifies.

Example 2: Review Recent Changes

# Get diff of recent changes
git diff HEAD~1 > /tmp/recent-changes.diff

# Step 1: Have Codex review the diff
codex exec -C /project -s read-only -o /tmp/codex-review.md \
  "Review the changes in the last commit. Check for bugs, security issues, and improvements needed."

# Step 2: Read and apply fixes
cat /tmp/codex-review.md

Example 3: Full Project Review

# Step 1: Comprehensive review
codex exec -C /project -s read-only -o /tmp/codex-review.md \
  "Perform a comprehensive code review of src/. Focus on:
   1. Security vulnerabilities (OWASP Top 10)
   2. Error handling patterns
   3. Performance bottlenecks
   4. Code duplication
   Prioritize issues by severity (critical/high/medium/low)."

# Step 2: Read prioritized feedback
cat /tmp/codex-review.md

Review Request Format

When asking Codex for review, include:

Review <target_files_or_directory>.

Context:
- Project type: <TypeScript/Python/etc>
- Framework: <Express/React/etc>
- Focus areas: <security/performance/quality>

Check for:
1. Security vulnerabilities
2. Performance issues
3. Error handling
4. Code quality
5. Edge cases

Output format:
For each issue:
- File: <path>
- Line: <number>
- Severity: critical/high/medium/low
- Issue: <description>
- Fix: <specific code change>

Applying Fixes

After receiving Codex feedback, apply fixes systematically:

1. Parse the review - Extract each issue with file, line, severity
2. Prioritize - Fix critical/high issues first
3. Read file - Use Read tool to see current code
4. Apply fix - Use Edit tool with precise old_string/new_string
5. Track progress - Mark each issue as fixed

Prerequisites

Codex CLI must be installed and authenticated:

# Install via npm
npm install -g @openai/codex

# Or via Homebrew (macOS)
brew install --cask codex

# Authenticate
codex login

Command Reference

Basic Command Pattern

codex exec [options] "<task_description>"

Core Options

AI-to-AI Communication

When communicating with Codex, PRIORITIZE ACCURACY AND PRECISION:

• Use structured data and exact technical terms
• Provide full file paths and precise details
• Include relevant context from the current codebase
• NO conversational formatting needed

Other Use Cases

Cross-Verification (after Claude implements)

codex exec -C /project -s read-only \
  "Verify the implementation in src/feature/. Check correctness and edge cases."

Get Alternative Implementation

codex exec -C /project -s read-only -o /tmp/alternative.md \
  "Propose an alternative implementation for the caching in src/cache/manager.ts"

Debugging Assistance

codex exec -C /project -s read-only \
  "Debug: tests in tests/auth.test.ts failing with timeout. Analyze root cause."

Session Management

For multi-turn reviews:

# Initial review
codex exec -C /project -s read-only "Review src/api/ for security issues"
# Note session ID from output

# Follow-up after fixes
codex exec resume <session_id> "I've applied the fixes. Please re-verify."

Troubleshooting

Authentication Issues

codex logout
codex login

Check Installation

codex --version
which codex

See Also

• sandbox-modes.md - Sandbox security levels
• examples.md - More usage examples
• advanced.md - Advanced configuration