Codex CLI and Responses endpoint

Quick answer

Set wire_api = responses in config.toml. Store only OPENAI_API_KEY in auth.json, and select a model from /v1/models.

Wire API: responses
Config: ~/.codex/config.toml
Auth: ~/.codex/auth.json
Key: OPENAI_API_KEY

Provider configuration

~/.codex/config.tomltoml

model_provider = "51cowork"
model = "<model-from-v1-models>"

[model_providers."51cowork"]
name = "51cowork"
base_url = "https://api.51cowork.com"
wire_api = "responses"
requires_openai_auth = true

Authentication file

~/.codex/auth.jsonjson

{
  "OPENAI_API_KEY": "<key-from-dashboard>"
}

Restart and verify

Merge an existing config.toml instead of replacing other providers.
Quit and restart the CLI or extension completely.
Create a new task, send a minimal request, and verify request_id in Usage.