dev/code-rs

Codex CLI (Rust Implementation)

We provide Codex CLI as a standalone, native executable to ensure a zero-dependency install.

Installing Codex

Today, the easiest way to install Codex is via npm:

npm i -g @openai/codex
codex

You can also install via Homebrew (brew install codex) or download a platform-specific release directly from our GitHub Releases.

What's new in the Rust CLI

The Rust implementation is now the maintained Codex CLI and serves as the default experience. It includes a number of features that the legacy TypeScript CLI never supported.

Config

Codex supports a rich set of configuration options. Note that the Rust CLI uses config.toml instead of config.json. See docs/config.md for details.

Model Context Protocol Support

Codex CLI functions as an MCP client that can connect to MCP servers on startup. See the mcp_servers section in the configuration documentation for details.

It is still experimental, but you can also launch Codex as an MCP server by running codex mcp-server. Use the @modelcontextprotocol/inspector to try it out:

npx @modelcontextprotocol/inspector codex mcp-server

Use codex mcp to add/list/get/remove MCP server launchers defined in config.toml, and codex mcp-server to run the MCP server directly.

Notifications

You can enable notifications by configuring a script that is run whenever the agent finishes a turn. The notify documentation includes a detailed example that explains how to get desktop notifications via terminal-notifier on macOS.

codex exec to run Codex programmatically/non-interactively

To run Codex non-interactively, run codex exec PROMPT (you can also pass the prompt via stdin) and Codex will work on your task until it decides that it is done and exits. Output is printed to the terminal directly. You can set the RUST_LOG environment variable to see more about what's going on.

Use @ for file search

Typing @ triggers a fuzzy-filename search over the workspace root. Use up/down to select among the results and Tab or Enter to replace the @ with the selected path. You can use Esc to cancel the search.

Esc–Esc to edit a previous message

When the chat composer is empty, press Esc to prime “backtrack” mode. Press Esc again to open a transcript preview highlighting the last user message; press Esc repeatedly to step to older user messages. Press Enter to confirm and Codex will fork the conversation from that point, trim the visible transcript accordingly, and pre‑fill the composer with the selected user message so you can edit and resubmit it.

In the transcript preview, the footer shows an Esc edit prev hint while editing is active.

--cd/-C flag

Sometimes it is not convenient to cd to the directory you want Codex to use as the "working root" before running Codex. Fortunately, codex supports a --cd option so you can specify whatever folder you want. You can confirm that Codex is honoring --cd by double-checking the workdir it reports in the TUI at the start of a new session.

Shell completions

Generate shell completion scripts via:

code completion bash
code completion zsh
code completion fish

Experimenting with the Codex Sandbox

To test to see what happens when a command is run under the sandbox provided by Codex, we provide the following subcommands in Codex CLI:

# macOS
codex debug seatbelt [--full-auto] [COMMAND]...

# Linux
codex debug landlock [--full-auto] [COMMAND]...

Selecting a sandbox policy via --sandbox

The Rust CLI exposes a dedicated --sandbox (-s) flag that lets you pick the sandbox policy without having to reach for the generic -c/--config option:

# Run Codex with the default, read-only sandbox
codex --sandbox read-only

# Allow the agent to write within the current workspace while still blocking network access
codex --sandbox workspace-write

# Danger! Disable sandboxing entirely (only do this if you are already running in a container or other isolated env)
codex --sandbox danger-full-access

The same setting can be persisted in ~/.code/config.toml via the top-level sandbox_mode = "MODE" key (Code will also read legacy ~/.codex/config.toml), e.g. sandbox_mode = "workspace-write".

If you want to prevent the agent from updating Git metadata (e.g., local safety), you can opt‑out with a workspace‑write tweak:

sandbox_mode = "workspace-write"

[sandbox_workspace_write]
allow_git_writes = false   # default is true; set false to protect .git

TUI anti-truncation fallback

If the transcript's last line intermittently clips, Codex keeps a guarded bottom spacer enabled. The TUI adds a 1–2 row overscan pad when the computed history height looks like it might land flush with the viewport, reducing the chance the final row disappears mid-stream. Enable RUST_LOG=debug to log when the fallback fires while you iterate on layouts.

Debugging Virtual Cursor

Use these console helpers to diagnose motion/cancellation behavior when testing in a real browser:

• Disable clickPulse transforms and force long CSS duration:

  window.__vc && (window.__vc.clickPulse = () => (console.debug('[VC] clickPulse disabled'), 0), window.__vc.setMotion({ engine: 'css', cssDurationMs: 10000 }))

• Wrap moveTo to log duplicates with sequence and inter-call delta:

  (() => { const vc = window.__vc; if (!vc || vc.__wrapped) return; const orig = vc.moveTo; let seq=0, last=0; vc.moveTo = function(x,y,o){ const now=Date.now(); console.debug('[VC] moveTo call',{seq:++seq,x,y,o,sincePrevMs:last?now-last:null}); last=now; return orig.call(this,x,y,o); }; vc.__wrapped = true; console.debug('[VC] moveTo wrapper installed'); })();

• Trigger a test move (adjust coordinates as needed):

  window.__vc && window.__vc.moveTo(200, 200)

Code Organization

This folder is the root of a Cargo workspace. It contains quite a bit of experimental code, but here are the key crates:

• core/ contains the business logic for Codex. Ultimately, we hope this to be a library crate that is generally useful for building other Rust/native applications that use Codex.
• exec/ "headless" CLI for use in automation.
• tui/ CLI that launches a fullscreen TUI built with Ratatui.
• cli/ CLI multitool that provides the aforementioned CLIs via subcommands.