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Overview

Codex CLI is OpenAI’s terminal-based coding agent. It can be configured to use Znap AI through an OpenAI-compatible endpoint.

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Step 1: Install Codex CLI

Install globally using npm:
Verify installation:

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Step 2: Log Out of Existing OpenAI Sessions

If you have previously logged into Codex using a ChatGPT account, clear the existing authentication first:
This ensures Codex uses your custom configuration instead of stored OpenAI credentials.

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Step 3: Configure Codex

Open the config file:
Add the following:
Save the file.

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Step 4: Start Codex

Launch the CLI:
Codex Terminal
When prompted, select:
Paste your Znap AI API key.

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Step 5: Verify Setup

Run a simple prompt:
If Codex responds successfully, the configuration is working.

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Changing Models

Update the model field in your configuration file:
Example:
Restart Codex after making changes.

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Notes

  • Codex uses the OpenAI Responses API internally.
  • Znap AI successfully routes Codex requests through its OpenAI-compatible endpoint.
  • At the time of writing, GPT-based models have been verified to work reliably with Codex.
  • If you encounter errors such as:
    try switching to a GPT-based model and restart Codex.

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Troubleshooting

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Requests Still Going to OpenAI

Run:
Then restart Codex and re-enter your Znap AI API key.

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Invalid API Key Error

Ensure you are using your Znap AI API key and not an OpenAI API key.

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Stream Disconnected Before Completion

This usually indicates a compatibility issue between the selected model and Codex’s Responses API requirements. Switch back to a GPT-based model:
and restart Codex.

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Current Recommendation

For Codex CLI, the most reliable configuration currently tested is:
This configuration has been verified to work successfully with Znap AI.