OpenAI Codex 0.39.0 Update: Comprehensive Guide to New Features and Improvements¶
Target Audience
- Developers who use OpenAI Codex daily and want to efficiently understand the latest features
Key Points¶
- Understand key changes from versions 0.36.0 to 0.39.0
- Learn how to use the new
/reviewcommand - Grasp GPT-5-Codex features and utilization methods
Core of the Update¶
OpenAI Codex has undergone significant improvements from version 0.36.0 to 0.39.0, including authentication system changes, GPT-5-Codex introduction, and new review functionality that greatly enhance the developer experience. Version 0.36.0 contains breaking changes that require attention.
Major Changes¶
0.36.0: Important Breaking Changes¶
Authentication System Changes - Discontinued automatic reading of OPENAI_API_KEY environment variable - Introduced new login flow and TUI onboarding
GPT-5-Codex Model Introduction - New model optimized for coding tasks - Achieved higher accuracy in code generation and understanding
Session Resume Feature
# Resume previous conversations
codex resume
0.37.0-0.38.0: Quality Improvements¶
- Enhanced npm release process
- Added package provenance badge
- Strengthened notification system
0.39.0: New Review Functionality¶
Added /review Command
# Execute code review
/review
- Improved conversation and sandbox handling
- Enhanced transcript display
- Unified animations
Common Issues and Solutions¶
| Symptom | Cause | Solution |
|---|---|---|
OPENAI_API_KEY not found | Environment variable discontinued | Use new login flow |
codex resume not working | Outdated version | Update to v0.36.0 or later |
/review command error | Version mismatch | Update to v0.39.0 |
Advanced Configuration (For Advanced Users - Click to Expand)
### GPT-5-Codex Optimization Settings Maximize GPT-5-Codex performance with project-specific configurations:{
"model": "gpt-5-codex",
"context_window": "extended",
"code_completion": "enhanced"
}
# Remove old environment variable
unset OPENAI_API_KEY
# Execute new login flow
codex login