Codex CLI

Codex CLI talks to models over the OpenAI Responses API. Hyphen serves it at /v1/responses, so Codex works against any Hyphen model with one provider block.

1. Get a key

app.hyphen-solution.com → sign in → Dashboard → API Keys → Create. Copy the sk-hy-... key.

2. Configure — one copy-paste block

Add this to ~/.codex/config.toml (create it if it doesn't exist):

Code
# ~/.codex/config.toml

model = "m3"
model_provider = "hyphen"

[model_providers.hyphen]
name = "Hyphen"
base_url = "https://api.hyphen-solution.com/v1"
env_key = "HYPHEN_API_KEY"
wire_api = "responses"

Then provide the key in the environment variable Codex reads (env_key):

Code
export HYPHEN_API_KEY="sk-hy-YOUR_KEY"

That's it. Run Codex from a shell that has HYPHEN_API_KEY set.

The Responses ⇄ Chat bridge

Codex only POSTs to /responses — since February 2026, wire_api = "responses" is the only value it supports. But most upstream models speak Chat Completions, not Responses. The Hyphen gateway sits in the middle and translates Responses ⇄ Chat Completions for you:

Code
Codex ──(Responses API)──▶  Hyphen gateway ──(translates)──▶  upstream model

That translation is the whole point: Codex gets the Responses shape it requires, even for upstreams that never implemented it. You don't configure anything for this — it's automatic.

Key fields in the block above:

• base_url — the OpenAI-compatible root, ending in /v1 (no trailing slash). Codex appends /responses.
• env_key — the environment variable Codex reads your key from at runtime. Never hard-code the key in TOML.
• wire_api = "responses" — required (the only supported value since Feb 2026).
• model / model_provider — select the Hyphen provider and m3 (strongest) by default.

3. Verify

Code
codex "Reply with the single word: connected"

If Codex replies connected, you're wired to the gateway. Override the model per-invocation when you want something cheaper:

Code
codex -m m2.5 "quick one-off edit"

Troubleshooting

• Auth errors — confirm HYPHEN_API_KEY is set in the shell you launched Codex from (echo $HYPHEN_API_KEY).
• 404 / wrong path — base_url must end in /v1, with no trailing slash.
• 429 — monthly budget spent; see Rate limits & caps.
• Config keys moved? Codex's provider schema has shifted across releases. Confirm the current shape for your version at developers.openai.com/codex/config-reference or with codex --help.