Marius Wichtner
3c711f3d16
## **Problem** Codex’s TUI uses a single “task running” indicator (spinner + Esc interrupt hint) to communicate “the UI is busy”. In practice, “busy” can mean two different things: an agent turn is running, or MCP servers are still starting up. Without a clear contract, those lifecycles can interfere: startup completion can clear the spinner while a turn is still in progress, or the UI can appear idle while MCP is still booting. This is user-visible confusion during the most important moments (startup and the first turn), so it was worth making the contract explicit and guarding it. ## **Mental model** `ChatWidget` is the UI-side adapter for the `codex_core::protocol` event stream. It receives `EventMsg` events and updates two major UI surfaces: the transcript (history/streaming cells) and the bottom pane (composer + status indicator). The key concept after this change is that the bottom pane’s “task running” indicator is treated as **derived UI-busy state**, not “agent is running”. It is considered active while either: - an agent turn is in progress (`TurnStarted` → completion/abort), or - MCP startup is in progress (`McpStartupUpdate` → `McpStartupComplete`). Those lifecycles are tracked independently, and the bottom-pane indicator is defined as their union. ## **Non-goals** - This does not introduce separate UI indicators for “turn busy” vs “MCP busy”. - This does not change MCP startup behavior, ordering guarantees, or core protocol semantics. - This does not rework unrelated status/header rendering or transcript layout. ## **Tradeoffs** - The “one flag represents multiple lifecycles” approach remains lossy: it preserves correct “busy vs idle” semantics but cannot express *which* kind of busy is happening without further UI changes. - The design keeps complexity low by keeping a single derived boolean, rather than adding a more expressive bottom-pane state machine. That’s chosen because it matches existing UX and minimizes churn while fixing the confusion. ## **Architecture** - `codex-core` owns the actual lifecycles and emits `codex_core::protocol` events. - `ChatWidget` owns the UI interpretation of those lifecycles. It is responsible for keeping the bottom pane’s derived “busy” state consistent with the event stream, and for updating the status header when MCP progress updates arrive. - The bottom pane remains a dumb renderer of the single “task running” flag; it does not learn about MCP or agent turns directly. ## **Observability** - When working: the spinner/Esc hint stays visible during MCP startup and does not disappear mid-turn when `McpStartupComplete` arrives; startup status headers can update without clearing “busy” for an active turn. - When broken: you’ll see the spinner/hint flicker off while output is still streaming, or the UI appears idle while MCP startup status is still changing. ## **Tests** - Adds/strengthens a regression test that asserts MCP startup completion does not clear the “task running” indicator for an active turn (in both `tui` and `tui2` variants). - These tests prove the **contract** (“busy is the union of turn + startup”) at the UI boundary; they do not attempt to validate MCP startup ordering, real-world startup timing, or backend integration behavior. Fixes #7017 Signed-off-by: 2mawi2 <2mawi2@users.noreply.github.com> Co-authored-by: 2mawi2 <2mawi2@users.noreply.github.com> Co-authored-by: Josh McKinney <joshka@openai.com>
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 --cask codex) or download a platform-specific release directly from our GitHub Releases.
Documentation quickstart
- First run with Codex? Start with
docs/getting-started.md(links to the walkthrough for prompts, keyboard shortcuts, and session management). - Want deeper control? See
docs/config.mdanddocs/install.md.
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
MCP client
Codex CLI functions as an MCP client that allows the Codex CLI and IDE extension to connect to MCP servers on startup. See the configuration documentation for details.
MCP server (experimental)
Codex can be launched as an MCP server by running codex mcp-server. This allows other MCP clients to use Codex as a tool for another agent.
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. When Codex detects that it is running under WSL 2 inside Windows Terminal (WT_SESSION is set), the TUI automatically falls back to native Windows toast notifications so approval prompts and completed turns surface even though Windows Terminal does not implement OSC 9.
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.
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 sandbox macos [--full-auto] [--log-denials] [COMMAND]...
# Linux
codex sandbox linux [--full-auto] [COMMAND]...
# Windows
codex sandbox windows [--full-auto] [COMMAND]...
# Legacy aliases
codex debug seatbelt [--full-auto] [--log-denials] [COMMAND]...
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 ~/.codex/config.toml via the top-level sandbox_mode = "MODE" key, e.g. sandbox_mode = "workspace-write".
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.