Codex

Codex CLI can run through BitRouter without taking over your Codex config. The quickest path is bitrouter launch --agent codex, which injects one-shot Codex config overrides for that child process only; if you prefer a permanent setup, register BitRouter as a custom provider in ~/.codex/config.toml.

Prerequisites

• BitRouter running — local proxy at http://127.0.0.1:4356, or BitRouter Cloud at https://api.bitrouter.ai.

• Codex installed:

  curl -fsSL https://chatgpt.com/codex/install.sh | sh

Launch through BitRouter

bitrouter launch --agent codex

Everything after -- is forwarded to Codex:

bitrouter launch --agent codex -- --model openai/gpt-5-codex

Before launching a long run, ask BitRouter to check the route it will use:

bitrouter launch --agent codex --check -- --model openai/gpt-5-codex

The check verifies that codex is installed, the BitRouter base URL is reachable, and the forwarded model has at least one Responses-compatible endpoint. It does not require the provider to be openai-codex; any model source that routes over the Responses protocol can be used by the Codex harness.

spawn does not edit ~/.codex/config.toml. It starts from your existing Codex model selection, then points Codex at a transient bitrouter provider with base_url = "<BitRouter>/v1" and wire_api = "responses". If BITROUTER_API_KEY is exported, Codex uses it through env_key; otherwise BitRouter injects a local placeholder that works with the skip_auth: true default written by bitrouter init.

Permanent config

Add a provider block to ~/.codex/config.toml. The base_url includes /v1 — Codex appends the route (/responses) itself.

model_provider = "bitrouter"

[model_providers.bitrouter]
name = "BitRouter"
base_url = "http://127.0.0.1:4356/v1"
wire_api = "responses"
# env_key = "BITROUTER_API_KEY"  # Cloud or authenticated local daemon

codex

Pick a model

The Codex model setting, or a per-run codex --model <id>, can use any registry id in provider/model form — openai/gpt-5-codex, anthropic/claude-sonnet-4-6, google/gemini-2.5-pro — optionally with a :cost or :latency variant. See Models.

Verify

Run codex and issue a prompt; check BitRouter's request finished log line (~/.bitrouter/bitrouter.log for a local install) to see which provider and model answered.

Learn more

• Codex — configuration reference
• Model fallback · Provider selection