Codex traces: picker model is the orchestrator, subagents stay Luna
Melvin Vivas · X post · 2026-09-15 · Open on X
Topics: AI Agents, Tool Use & MCP, AI Dev Tools & Productivity · Level: intermediate
Summary
The creator checked the Codex traces. The model chosen in the model picker (Astra High) is the one used as the orchestrator, while subagents still run on Luna Medium as configured.
Key points
- The model you choose in the Codex model picker becomes the orchestrator.
- Subagents keep their separately configured model (Luna Medium).
- Use Codex traces to check which model actually runs each role.
Resources mentioned
- OpenAI Codex · tool · openai.com · paid
OpenAI's coding agent. In the diagram it writes code, fixes review findings and drives the build loop. The creator also used it to make this video.
Also in: An agent bot that installs and drives Codex on its own (Melvin Vivas on X · notes), Asking a Coder bot to install Codex (Melvin Vivas on X · notes), Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Codex Cloud Environments Must Be Saved & Published Before Use (Melvin Vivas on X · notes) and 240 more
Try this
- Check the Codex traces to confirm which model is acting as orchestrator and which as subagent.
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