Developer Reverse Engineers OpenAI's Codex CLI to Access GPT-5-Codex-Mini Model Directly
By
simonw
A baker's-dozen of insight crammed into one ring.
Summary
A developer reverse-engineered OpenAI's Codex CLI tool to gain direct access to the newly released GPT-5-Codex-Mini model, which OpenAI had only made available through their CLI and VS Code extension. The article documents the process of bypassing OpenAI's intended access restrictions to prompt the model directly, including creating a video demonstration of the results. The author acknowledges this approach is somewhat cheeky since OpenAI clearly didn't intend for direct model access yet.
Key quotes
· 4 pulledOpenAI partially released a new model yesterday called GPT-5-Codex-Mini, which they describe as 'a more compact and cost-efficient version of GPT-5-Codex'
It's currently only available via their Codex CLI tool and VS Code extension, with proper API access 'coming soon'
I decided to use Codex to reverse engineer the Codex CLI tool and give me the ability to prompt the new model directly
This is a little bit cheeky - OpenAI clearly don't intend for people to access this model directly
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