Michael Bolin
53cf12cd52
## What changed This PR makes the default Cargo dev profile use line-tables-only debug info: ```toml [profile.dev] debug = 1 ``` That keeps useful backtraces while avoiding the cost of full variable debug info in normal local dev builds. This also makes the Bazel CI setting explicit with `-Cdebuginfo=0` for target and exec-configuration Rust actions. Bazel/rules_rust does not read Cargo profiles for this setting, and the current fastbuild action already emitted `--codegen=debuginfo=0`; the Bazel part of this PR makes that choice direct in our build configuration. ## Why The slow codex-core rebuilds are dominated by debug-info codegen, not parsing or type checking. On a warm-dependency package rebuild, the baseline codex-core compile was about 39.5s wall / 38.9s rustc total, with codegen_crate around 14.0s and LLVM_passes around 13.4s. Setting codex-core to line-tables-only debug info brought that to about 27.2s wall / 26.7s rustc total, with codegen_crate around 3.1s and LLVM_passes around 2.8s. `debug = 0` was only about another 0.7s faster than `debug = 1` in the codex-core measurement, so `debug = 1` is the better default dev tradeoff: it captures nearly all of the compile-time win while preserving basic debuggability. I also sampled other first-party crates instead of keeping a codex-core-only package override. codex-app-server showed the same pattern: rustc total dropped from 15.85s to 10.48s, while codegen_crate plus LLVM_passes dropped from about 13.47s to 3.23s. codex-app-server-protocol had a smaller but still real improvement, 16.05s to 14.58s total, and smaller crates showed modest wins. That points to a workspace dev-profile policy rather than a hand-maintained list of large crates. ## Relationship to #18612 [#18612](https://github.com/openai/codex/pull/18612) added the `dev-small` profile. That remains useful when someone wants a working local build quickly and is willing to opt in with `cargo build --profile dev-small`. This PR is deliberately less aggressive: it changes the common default dev profile while preserving line tables/backtraces. `dev-small` remains the explicit "build quickly, no debuggability concern" path. ## Other investigation I looked for another structural win comparable to [#16631](https://github.com/openai/codex/pull/16631) and [#16630](https://github.com/openai/codex/pull/16630), but did not find one. The attempted TOML monomorphization changes were noisy or worse in measurement, and the async task changes reduced some instantiations but only translated to roughly a one-second improvement while being much more disruptive. The debug-info setting was the one repeatable, material win that survived measurement. ## Verification - `just bazel-lock-update` - `just bazel-lock-check` - `cargo check -p codex-core --lib` - `cargo test -p codex-core --lib` - Bazel `aquery --config=ci-linux` confirmed `--codegen=debuginfo=0` and `-Cdebuginfo=0` for `//codex-rs/core:core` --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/openai/codex/pull/18844). * #18846 * __->__ #18844
Codex CLI (Rust Implementation)
We provide Codex CLI as a standalone 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. If you provide both a prompt argument and piped stdin, Codex appends stdin as a <stdin> block after the prompt so patterns like echo "my output" | codex exec "Summarize this concisely" work naturally. Output is printed to the terminal directly. You can set the RUST_LOG environment variable to see more about what's going on.
Use codex exec --ephemeral ... to run without persisting session rollout files to disk.
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".
In workspace-write, Codex also includes ~/.codex/memories in its writable roots so memory maintenance does not require an extra approval.
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.
If you want to contribute or inspect behavior in detail, start by reading the module-level README.md files under each crate and run the project workspace from the top-level codex-rs directory so shared config, features, and build scripts stay aligned.