Codex CLI is OpenAI’s local coding agent. The commands and config.toml fields below follow the official Codex repository and custom-provider reference. NexusAPI supplies only the Base URL, API key, and model ID.
1. Install Codex CLI
Choose one official installation method.
Windows PowerShell
macOS, Linux, or WSL
With Node.js already installed
Verify installation:
2. Create a compatible key
In NexusAPI console → Token Management → Add token, select a group containing the exact Codex-compatible model you need. Use a recognizable name and a suitable project limit. Check the capability matrix rather than assuming a Claude-type channel works with Responses.
Open the user configuration file:
Replace YOUR_MODEL_ID with the exact model ID available to the key. Do not put the actual key in this file.
Do not write a NexusAPI key to auth.json~/.codex/auth.json is Codex’s OpenAI login cache. The configuration above reads the key from env_key; keep NexusAPI credentials out of auth.json, source code, and screenshots.
4. Set the environment variable
Windows PowerShell
Open a new terminal after running this command.
macOS, Linux, or WSL
This affects only the current shell. For long-term storage, use your system’s credential or shell-environment management; never add the key to a repository.
5. Verify safely
For the first task, use a read-only instruction such as: Explain the repository layout without changing files. Then check the console usage log.
Troubleshooting
- Use a newly opened terminal so
NEXUSAPI_API_KEY is available.
- Confirm the key is enabled, funded, and assigned to the right group.
- Recopy the exact model ID from the Model Marketplace or
/v1/models.
- Save the complete error and Request ID, then use the self-check guide.
For editor use, install the Codex extension published by OpenAI. It uses the same user-level Codex configuration; do not add legacy chatgpt.apiBase settings. 