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Codex Setup Guide | Let AI RunCodex Setup Guide
This guide shows how to install OpenAI Codex on macOS and Windows, then connect it to Let AI Run.
1. Prepare Your API Key
Prepare a valid Let AI Run key first (typically starts with sk-). You will place it in auth.json.
2. Install on macOS
brew install codex
If Node.js is already installed, you can also install with npm:
npm install -g @openai/codex
3. Configure on macOS
Create the hidden config directory first:
mkdir -p ~/.codex
Create ~/.codex/config.toml with:
model_provider = "letairun"
model = "gpt-5.4"
model_reasoning_effort = "xhigh"
disable_response_storage = true
network_access = "enabled"
model_verbosity = "high"
[model_providers.letairun]
name = "letairun"
base_url = "https://api.letai.run/v1"
wire_api = "responses"
requires_openai_auth = true
[features]
fast_mode = false
prevent_idle_sleep = true
streamable_shell = false
Create ~/.codex/auth.json:
{
"OPENAI_API_KEY": "your-api-key-here"
}
Replace your-api-key-here with your real API key.
4. Install on Windows
- Install Node.js:
https://nodejs.org/zh-cn/download/current
- Install Codex:
npm install -g @openai/codex
5. Configure on Windows
Create this folder (note the leading .):
Create %USERPROFILE%\\.codex\\config.toml:
model_provider = "letairun"
model = "gpt-5.4"
model_reasoning_effort = "xhigh"
disable_response_storage = true
network_access = "enabled"
windows_wsl_setup_acknowledged = true
model_verbosity = "high"
[model_providers.letairun]
name = "letairun"
base_url = "https://api.letai.run/v1"
wire_api = "responses"
requires_openai_auth = true
[features]
fast_mode = false
prevent_idle_sleep = true
streamable_shell = false
Create %USERPROFILE%\\.codex\\auth.json:
{
"OPENAI_API_KEY": "your-api-key-here"
}
6. How To Start
- Terminal: run
codex
- VSCode / Cursor: install the official OpenAI
Codex extension
7. Troubleshooting
codex command not found:
- Confirm installation completed successfully.
- If installed via npm, make sure the global npm bin path is in
PATH.
- Authentication failed:
- Check
auth.json file name and location.
- Make sure
OPENAI_API_KEY is your real key, not the placeholder.
- Requests are not routed to Let AI Run:
- Verify
base_url is https://api.letai.run/v1 in config.toml.