# `Alloy.Provider.Codex`
[🔗](https://github.com/alloy-ex/alloy/blob/v0.10.1/lib/alloy/provider/codex.ex#L1)

Provider for ChatGPT-plan-backed Codex execution via `codex exec`.

This provider treats Codex as a structured completion backend rather than a
full agent runtime. Alloy remains responsible for the tool loop, while Codex
receives the current transcript and available tool definitions, then returns
JSON describing either a final assistant response or one or more tool calls.

## Config

Required:
- `:model` - Codex model name (for example `"gpt-5.4"`)

Optional:
- `:codex_bin` - Executable path (default: `"codex"`)
- `:workdir` - Directory passed to `codex exec` (defaults to a temp dir)
- `:profile` - Optional Codex config profile
- `:codex_home` - Override `CODEX_HOME` instead of creating an isolated temp home
- `:command_runner` - Test hook matching `System.cmd/3`
- `:system_prompt` - System prompt string

## Notes

- Authentication is handled by the local `codex` CLI login state.
- By default the provider creates a minimal temporary `CODEX_HOME` containing
  only `auth.json`, which avoids pulling in the user's full MCP/plugin config.
- Usage accounting is not exposed by `codex exec` in a structured form yet,
  so this provider currently reports zero token counts.
- Streaming is emulated by running a normal completion and replaying the final
  text to the provided callback.

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*Consult [api-reference.md](api-reference.md) for complete listing*