Install or update Codex
Use the current Codex CLI, then run codex --version so the installed client supports the Responses API route.
Codex / Agent Plan reference
Codex integration reference
Connect Codex CLI or the Codex desktop app to the one-time Agent Plan key with a native Responses API route.
1 · Quick start
Connect Codex in three moves
Start with the matching configuration file, keep the key in the named secret location, and use one exact Model ID throughout the setup.
Create the config file
On macOS and Linux, edit ~/.codex/config.toml. The Codex desktop app can open the same file from its settings screen.
Add the key to your shell
Set ARK_API_KEY in the shell that launches Codex. Keep the key out of config.toml, source control, and screenshots.
The key is delivered to your Dashboard after payment. Replace the placeholder in the example, then keep the real value in your environment or local secret file.
2 · Configuration
Copy the provider blueprint
This is a safe starting point for the current Agent Plan route. Keep existing tool settings that are unrelated to the provider and replace only the placeholder key and Model ID values.
model = "glm-5.2"
model_provider = "volcengine-agent-plan"
model_supports_reasoning_summaries = true
[model_providers.volcengine-agent-plan]
name = "volcengine-agent-plan"
base_url = "https://ark.cn-beijing.volces.com/api/plan/v3"
env_key = "ARK_API_KEY"
wire_api = "responses"The default Model ID shown here is the stocked plan's current default. If you choose another supported model, replace every model field required by Codex, not just the visible label.
Install / launch
npm i -g @openai/codex3 · Verify the route
Confirm the connection before a full project
Run codex --version and confirm the client starts without an authentication prompt.
Start a short session and ask for a one-line response before opening a larger repository.
If the selected model does not support reasoning summaries, remove model_supports_reasoning_summaries = true.
Troubleshooting
Common configuration pitfalls
Use the /v3 endpoint with wire_api = "responses"; do not point Codex at the Claude-compatible base URL.
The env_key value is the variable name. The secret value belongs in ARK_API_KEY, not in the TOML file.