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This is a very large PR with some non-backwards-compatible changes. Historically, `codex mcp` (or `codex mcp serve`) started a JSON-RPC-ish server that had two overlapping responsibilities: - Running an MCP server, providing some basic tool calls. - Running the app server used to power experiences such as the VS Code extension. This PR aims to separate these into distinct concepts: - `codex mcp-server` for the MCP server - `codex app-server` for the "application server" Note `codex mcp` still exists because it already has its own subcommands for MCP management (`list`, `add`, etc.) The MCP logic continues to live in `codex-rs/mcp-server` whereas the refactored app server logic is in the new `codex-rs/app-server` folder. Note that most of the existing integration tests in `codex-rs/mcp-server/tests/suite` were actually for the app server, so all the tests have been moved with the exception of `codex-rs/mcp-server/tests/suite/mod.rs`. Because this is already a large diff, I tried not to change more than I had to, so `codex-rs/app-server/tests/common/mcp_process.rs` still uses the name `McpProcess` for now, but I will do some mechanical renamings to things like `AppServer` in subsequent PRs. While `mcp-server` and `app-server` share some overlapping functionality (like reading streams of JSONL and dispatching based on message types) and some differences (completely different message types), I ended up doing a bit of copypasta between the two crates, as both have somewhat similar `message_processor.rs` and `outgoing_message.rs` files for now, though I expect them to diverge more in the near future. One material change is that of the initialize handshake for `codex app-server`, as we no longer use the MCP types for that handshake. Instead, we update `codex-rs/protocol/src/mcp_protocol.rs` to add an `Initialize` variant to `ClientRequest`, which takes the `ClientInfo` object we need to update the `USER_AGENT_SUFFIX` in `codex-rs/app-server/src/message_processor.rs`. One other material change is in `codex-rs/app-server/src/codex_message_processor.rs` where I eliminated a use of the `send_event_as_notification()` method I am generally trying to deprecate (because it blindly maps an `EventMsg` into a `JSONNotification`) in favor of `send_server_notification()`, which takes a `ServerNotification`, as that is intended to be a custom enum of all notification types supported by the app server. So to make this update, I had to introduce a new variant of `ServerNotification`, `SessionConfigured`, which is a non-backwards compatible change with the old `codex mcp`, and clients will have to be updated after the next release that contains this PR. Note that `codex-rs/app-server/tests/suite/list_resume.rs` also had to be update to reflect this change. I introduced `codex-rs/utils/json-to-toml/src/lib.rs` as a small utility crate to avoid some of the copying between `mcp-server` and `app-server`.
npm i -g @openai/codex
or brew install codex
Codex CLI is a coding agent from OpenAI that runs locally on your computer.
If you want Codex in your code editor (VS Code, Cursor, Windsurf), install in your IDE
If you are looking for the cloud-based agent from OpenAI, Codex Web, go to chatgpt.com/codex
Quickstart
Installing and running Codex CLI
Install globally with your preferred package manager. If you use npm:
npm install -g @openai/codex
Alternatively, if you use Homebrew:
brew install codex
Then simply run codex to get started:
codex
You can also go to the latest GitHub Release and download the appropriate binary for your platform.
Each GitHub Release contains many executables, but in practice, you likely want one of these:
- macOS
- Apple Silicon/arm64:
codex-aarch64-apple-darwin.tar.gz - x86_64 (older Mac hardware):
codex-x86_64-apple-darwin.tar.gz
- Apple Silicon/arm64:
- Linux
- x86_64:
codex-x86_64-unknown-linux-musl.tar.gz - arm64:
codex-aarch64-unknown-linux-musl.tar.gz
- x86_64:
Each archive contains a single entry with the platform baked into the name (e.g., codex-x86_64-unknown-linux-musl), so you likely want to rename it to codex after extracting it.
Using Codex with your ChatGPT plan
Run codex and select Sign in with ChatGPT. We recommend signing into your ChatGPT account to use Codex as part of your Plus, Pro, Team, Edu, or Enterprise plan. Learn more about what's included in your ChatGPT plan.
You can also use Codex with an API key, but this requires additional setup. If you previously used an API key for usage-based billing, see the migration steps. If you're having trouble with login, please comment on this issue.
Model Context Protocol (MCP)
Codex CLI supports MCP servers. Enable by adding an mcp_servers section to your ~/.codex/config.toml.
Configuration
Codex CLI supports a rich set of configuration options, with preferences stored in ~/.codex/config.toml. For full configuration options, see Configuration.
Docs & FAQ
- Getting started
- Sandbox & approvals
- Authentication
- Advanced
- Zero data retention (ZDR)
- Contributing
- Install & build
- FAQ
- Open source fund
License
This repository is licensed under the Apache-2.0 License.