An Intense Week for OpenAI Developers
The week of December 15-21, 2025 marks a turning point for the OpenAI developer ecosystem: GPT-5.2-Codex becomes the best model for agentic coding, Skills officially arrive in Codex CLI, and the API is enriched with GPT Image 1.5 and new audio models.
GPT-5.2-Codex: The Reference Agentic Coding Model
December 18, 2025 โ OpenAI launches GPT-5.2-Codex, a model optimized for complex software engineering in real-world conditions.
What is GPT-5.2-Codex?
GPT-5.2-Codex is a variant of GPT-5.2 specially trained for agentic coding. It excels in long tasks requiring context compaction, understanding of large codebases, and reliable tool calls.
Meet GPT-5.2-Codex, the best agentic coding model yet for complex, real-world software engineering. With native compaction, better long-context understanding, and improved tool-calling, it is a more dependable partner for your hardest tasks. โ @OpenAIDevs on X
Benchmarks
| Benchmark | GPT-5.2-Codex | GPT-5.1-Codex-Max |
|---|---|---|
| SWE-Bench Pro | 56.4% | โ |
| Terminal-Bench | 64% | โ |
| CTF Challenges | 160% | 100% (baseline) |
Cybersecurity: Impressive Progress
GPT-5.2-Codex significantly outperforms previous models in cybersecurity:
GPT-5.2-Codex is more cyber-capable than GPT-5.1-Codex-Max, and we expect future models to continue on this trajectory. This helps strengthen cybersecurity at scale by giving defenders more powerful tools, but also raises new dual-use risks that require careful deployment. โ @OpenAIDevs on X
Availability
| Plan | Access |
|---|---|
| ChatGPT Plus/Pro | Available in Codex |
| API | Coming soon |
| Advanced Cybersecurity | Guided access by invitation (defense) |
Codex Skills: Reusable Automation
December 19, 2025 โ Skills are now officially supported in Codex CLI, allowing for reusable automations.
๐ Codex now officially supports skills. Skills are reusable bundles of instructions, scripts, and resources that help Codex complete specific tasks. You can call a skill directly with $.skill-name, or let Codex choose the right one based on your prompt. โ @OpenAIDevs on X
How It Works
Skills are installed via $.skill-installer and activated with the $ prefix:
# Install a skill
$.skill-installer linear
# Use a skill
$.linearAvailable Skills
| Skill | Command | Function |
|---|---|---|
| Linear | $.skill-installer linear | Read and update Linear tickets |
| GitHub CI Fix | $.skill-installer gh-fix-ci | Automatically fix GitHub CI failures |
Linear Demonstration
Have Codex read and update your Linear tickets. โ @OpenAIDevs on X
GitHub CI Demonstration
Have Codex automatically fix GitHub CI failures. โ @OpenAIDevs on X
CLI Version
Skills are enabled by default as of version CLI 0.76.0 (December 19, 2025).
GPT Image 1.5: Image Generation in the API
December 16, 2025 โ GPT Image 1.5 arrives in the API with major improvements for editing and text rendering.
New Features
GPT Image 1.5 is now available in the API:
โ๏ธ More precise image editing and preservation of logos & faces ๐ฏ Better instruction following and adherence to prompts ๐ค Improved text rendering, particularly for denser and smaller text โ @OpenAIDevs on X
Key Improvements
| Feature | Improvement |
|---|---|
| Image Editing | More precise, preserves logos and faces |
| Instruction Following | Better adherence to prompts |
| Text Rendering | Improved for dense and small text |
| Speed | 4x faster than the previous version |
Notable Adoptions
Several major platforms have already integrated GPT Image 1.5:
- Figma โ Available in Figma Weave
- Wix โ Integration in the editor
- Canva โ Native image generation
๐ API Documentation
ChatGPT Apps: Directory for Developers
December 17, 2025 โ Developers can now submit their ChatGPT apps for publication in a directory accessible to all users.
How It Works
๐ฃ Calling all app developers! Starting today, you can submit your ChatGPT app for review. Approved apps will be listed in the app directory, a new surface for users to search for apps directly in ChatGPT. โ @OpenAIDevs on X
Ecosystem
| Aspect | Detail |
|---|---|
| Submission | Review by OpenAI |
| Discovery | Directory integrated into ChatGPT |
| Monetization | Coming soon |
Vision
This is just the start. Weโll continue to grow the app ecosystem in ChatGPT, improve discovery, and explore more ways for developers to reach users and monetize their work. โ @OpenAIDevs on X
Build Hour
OpenAI is organizing a webinar on January 21 to help developers build and submit their apps.
๐ Register
New Audio Models: Improved Transcription and TTS
December 15, 2025 โ New snapshots of audio models arrive in the Realtime API with significant improvements.
Available Models
| Model | Improvement |
|---|---|
| gpt-4o-mini-transcribe-2025-12-15 | 89% reduction in hallucinations vs Whisper-1 |
| gpt-4o-mini-tts-2025-12-15 | 35% fewer word errors |
Performance
๐ New audio model snapshots are now live in the Realtime API with improvements to reliability, lower error rates, and fewer hallucinations:
- gpt-4o-mini-transcribe-2025-12-15: 89% reduction in hallucinations compared to whisper-1
- gpt-4o-mini-tts-2025-12-15: 35% fewer word errors โ @OpenAIDevs on X
In Brief: Other Announcements
Teen Safety (December 18)
OpenAI updates its Model Spec to strengthen protections for minors and publishes AI literacy resources for teens and parents.
DOE Partnership (December 18)
OpenAI deepens its collaboration with the U.S. Department of Energy.
๐ Announcement
Chain-of-thought Monitorability (December 18)
Publication of research on the monitorability of model chains of thought.
๐ Research
What This Means
For Developers
This week consolidates OpenAIโs position as the platform of choice for AI development:
- Codex CLI becomes a complete productivity tool with Skills
- GPT-5.2-Codex pushes the boundaries of assisted coding
- ChatGPT Apps opens a new distribution channel
For the Ecosystem
The arrival of Skills and the app directory creates an ecosystem where third-party developers and OpenAI co-build solutions.
For Security
GPT-5.2-Codex raises dual-use questions in cybersecurity. OpenAI adopts a gradual deployment approach with guided access for the most advanced capabilities.