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Codex supports custom model providers through config.toml, so you can route Codex requests through Phaseo while keeping the same CLI, app, or IDE workflow. If you also want Codex to read the live Phaseo documentation while it works, add the Docs MCP server as well.
Need reusable agent setup help as well as provider wiring? Install the public Phaseo skills from phaseoteam/skills:

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Set up with the Phaseo CLI

Setup installs Codex when needed, creates a non-expiring Phaseo CLI: Codex API Key, stores it in the OS credential store, and writes a dedicated Phaseo profile. Codex retrieves the key through the CLI helper, so no plaintext key is written to config.toml. Start Codex with:

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Manual configuration

Create or update your user config at ~/.codex/config.toml. For a trusted project, you can also place the same settings in .codex/config.toml inside the repo.
Codex currently uses the Responses wire protocol for custom providers. Keep wire_api = "responses" or omit it and use the default. The Codex App and IDE extension share the same config layers. In the IDE extension, open the config from Codex Settings > Open config.toml.

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Verification

  • Confirm your model id exists in Models before launching.
  • Use Responses for the default Codex-style flow.

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Troubleshooting

  • 401 Unauthorized: run phaseo whoami, then rerun phaseo codex.
  • model_not_found: fetch a current id from Models and update model.
  • Provider-specific issues: follow Routing and fallbacks for failover behavior.
Last modified on August 14, 2026