Setting Up Codex

Configuration Example

Add a separate profile to ~/.codex/config.toml:

model = "gpt-5.5"
model_provider = "nexus"

[model_providers.nexus]
name = "Nexus"
base_url = "https://api.nexus-hub.ru/v1"
env_key = "NEXUS_API_KEY"
wire_api = "responses"

Set the key:

export NEXUS_API_KEY="your_nexus_key"

Verification

Start Codex and make sure it uses a model from the GET /v1/models list.

If you change the model manually, choose only a value that is available for your key.