Files
codex/codex-rs
jgershen-oai 9e905528bb Fix custom CA login behind TLS-inspecting proxies (#20676)
Refs:
https://linear.app/openai/issue/SE-6311/login-fails-for-experian-users-behind-tls-inspecting-proxy

## Summary
- When a custom CA bundle is configured, force the shared `codex-client`
reqwest builder onto rustls before registering custom roots.
- Add the `rustls-tls-native-roots` reqwest feature so the rustls client
preserves native roots plus the enterprise CA bundle.
- Add subprocess TLS coverage for both a direct local TLS 1.3 server and
a hermetic local CONNECT TLS-intercepting proxy that forwards a
token-exchange-shaped POST to a local origin.

## Plain-language explanation
Experian users are behind a TLS-inspecting proxy, so the login token
exchange needs to trust the enterprise CA bundle from
`CODEX_CA_CERTIFICATE` or `SSL_CERT_FILE`. Before this change, that
custom-CA branch still used reqwest default TLS selection, which could
fail in the proxy environment. Now, only when a custom CA is configured,
Codex selects rustls first and then adds the custom CA roots, matching
the validated behavior from the Experian test build while leaving normal
system-root clients unchanged.

The new regression test recreates the enterprise-proxy shape locally:
the probe client sends an HTTPS `POST /oauth/token` through an explicit
HTTP CONNECT proxy, the proxy presents a leaf certificate signed by a
runtime-generated test CA, decrypts the request, forwards it to a local
origin, and relays the `ok` response back.

## Scope note
- The actual production fix is the first commit: `8368119282 Fix custom
CA reqwest clients to use rustls`.
- The second commit is integration-test coverage only. It generates all
test CA and localhost certificate material at runtime.

## Validation
- `cd codex-rs && cargo test -p codex-client --test ca_env
posts_to_token_origin_through_tls_intercepting_proxy_with_custom_ca_bundle
-- --nocapture`
- `cd codex-rs && cargo test -p codex-client`
- `cd codex-rs && cargo test -p codex-login`
- `cd codex-rs && just fmt`
- `cd codex-rs && just bazel-lock-update`
- `cd codex-rs && just bazel-lock-check`
- `cd codex-rs && just fix -p codex-client`
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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

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

The legacy notify setting is deprecated and will be removed in a future release. Existing configurations still work, but new automation should use lifecycle hooks instead. The notify documentation explains the remaining compatibility behavior. 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 [--log-denials] [COMMAND]...

# Linux
codex sandbox linux [COMMAND]...

# Windows
codex sandbox windows [COMMAND]...

# Legacy aliases
codex debug seatbelt [--log-denials] [COMMAND]...
codex debug landlock [COMMAND]...

To try a writable legacy sandbox mode with these commands, pass an explicit config override such as -c 'sandbox_mode="workspace-write"'.

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 becomes 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.