# Codex CLI

> Route the OpenAI Codex CLI through sference with a custom provider in ~/.codex/config.toml.

Source: https://sference.com/docs/sference-code/codex

The [Codex CLI](https://github.com/openai/codex) reads providers from `~/.codex/config.toml`. Add sference as a custom provider and select it as the active model provider.

## Configure

Add to `~/.codex/config.toml`:

```toml
model = "zai-org/GLM-5.3"
model_provider = "sference"

[model_providers.sference]
name = "Sference"
base_url = "https://api.sference.com/v1"
env_key = "SFERENCE_API_KEY"
wire_api = "chat"
```

Then export the key and run Codex:

```bash
export SFERENCE_API_KEY="sk_..."
codex
```

`env_key` names the environment variable Codex reads for the bearer token, so the key never lives in the config file.

> **`wire_api`: chat or responses**
>
> `wire_api = "chat"` uses `/v1/chat/completions`; `wire_api = "responses"` uses `/v1/responses`. sference serves both. Use `responses` if your Codex version supports it — it is the surface Codex is built around and it unlocks background steps.

## Choosing a model

```toml
model = "zai-org/GLM-5.3"          # general coding turns
# model = "zai-org/GLM-5.3-Flash"  # fast edits, 0.20 / 0.60 per 1M
# model = "moonshotai/Kimi-K3"     # hard planning, 3.00 / 15.00 per 1M
```

Live ids and rates: `GET https://api.sference.com/v1/models`.

## Switching providers

Keep your existing OpenAI configuration and switch by editing one line:

```toml
model_provider = "sference"   # or "openai"
```

Both providers stay configured, so you can move between them per session.

## Cost control

- **Prefix caching.** Codex resends the system prompt and tool definitions every turn. Keep them stable and first so they bill at the cached rate. See [Prompt caching](https://sference.com/docs/guides/prompt-caching).
- **`max_output_tokens` on reasoning models** covers hidden reasoning, so cap it to avoid burning budget before the agent acts.
- **Per-engineer attribution.** One key per engineer shows up separately in `GET /control/v1/usage/by-key`. See [Usage & analytics](https://sference.com/docs/usage).

> **It is a compatibility layer**
>
> Open models plan differently and call tools less reliably than frontier closed models on long repo work. Validate on your own repository before committing a workflow. See [SferenceCode](https://sference.com/docs/sference-code) for what to expect.

- [SferenceCode](https://sference.com/docs/sference-code): All harnesses, model choices, and what to expect.
- [Claude Code](https://sference.com/docs/sference-code/claude-code): One-command launch with hybrid routing.
- [API compatibility](https://sference.com/docs/compatibility): Which request fields sference honors.