e7e6267ab3
## Summary Moves the WebRTC realtime sideband websocket join out of the voice start critical path. Call creation still posts the SDP offer and session config synchronously so the client gets the SDP answer, but the sideband websocket now connects in the input task async and doesn't block conversation state installation. This lets the normal realtime input channels buffer text, handoff output, and audio while the WebRTC sideband websocket is connecting. If the sideband join fails while the conversation is still active, the task sends a RealtimeEvent::Error through the existing events_tx / fanout path. To rephrase this: * No longer blocked on sideband: the client can receive the SDP answer earlier, set up the WebRTC peer connection, and let the media leg progress while the sideband websocket joins. * Still blocked on sideband: queued text, handoff output, and sideband server events cannot flow until connect_webrtc_sideband(...).await finishes and then run_realtime_input_task(...) starts ## Validation - `env CODEX_SKIP_VENDORED_BWRAP=1 cargo test --manifest-path codex-rs/Cargo.toml -p codex-core --test all conversation_webrtc_start_posts_generated_session` `CODEX_SKIP_VENDORED_BWRAP=1` is needed in this local environment because `libcap.pc` is not installed for the vendored bubblewrap build. ## Testing I tested this locally by running `cargo run -p codex-cli --bin codex -- --enable realtime_conversation` and invoking `/realtime`. Then, we get logs emitted in `~/.codex/log/codex-tui.log`. ### Before the Change Logging commit (c0299e6edf) ``` 2026-05-04T16:06:09.251956Z INFO session_loop{thread_id=019df3b9-e3d8-7271-b13a-b880119aa4c2}:submission_dispatch{otel.name="op.dispatch.realtime_conversation_start" submission.id="019df3bd-65df-7ee2-8125-1d6701fe39d2" codex.op="realtime_conversation_start"}: codex_core::realtime_conversation: starting realtime conversation 2026-05-04T16:06:09.251980Z INFO session_loop{thread_id=019df3b9-e3d8-7271-b13a-b880119aa4c2}:submission_dispatch{otel.name="op.dispatch.realtime_conversation_start" submission.id="019df3bd-65df-7ee2-8125-1d6701fe39d2" codex.op="realtime_conversation_start"}: codex_core::realtime_conversation: creating realtime call transport="webrtc" 2026-05-04T16:06:10.365722Z INFO session_loop{thread_id=019df3b9-e3d8-7271-b13a-b880119aa4c2}:submission_dispatch{otel.name="op.dispatch.realtime_conversation_start" submission.id="019df3bd-65df-7ee2-8125-1d6701fe39d2" codex.op="realtime_conversation_start"}: codex_core::realtime_conversation: realtime call created; sdp answer ready transport="webrtc" call_id=rtc_u0_Dbq65nhak5eLjQZ73yhAy elapsed_ms=1113 total_elapsed_ms=1113 2026-05-04T16:06:10.365843Z INFO session_loop{thread_id=019df3b9-e3d8-7271-b13a-b880119aa4c2}:submission_dispatch{otel.name="op.dispatch.realtime_conversation_start" submission.id="019df3bd-65df-7ee2-8125-1d6701fe39d2" codex.op="realtime_conversation_start"}: codex_core::realtime_conversation: connecting realtime sideband websocket call_id=rtc_u0_Dbq65nhak5eLjQZ73yhAy 2026-05-04T16:06:10.784528Z INFO session_loop{thread_id=019df3b9-e3d8-7271-b13a-b880119aa4c2}:submission_dispatch{otel.name="op.dispatch.realtime_conversation_start" submission.id="019df3bd-65df-7ee2-8125-1d6701fe39d2" codex.op="realtime_conversation_start"}: codex_core::realtime_conversation: connected realtime sideband websocket call_id=rtc_u0_Dbq65nhak5eLjQZ73yhAy elapsed_ms=418 total_elapsed_ms=1532 2026-05-04T16:06:10.784665Z INFO session_loop{thread_id=019df3b9-e3d8-7271-b13a-b880119aa4c2}:submission_dispatch{otel.name="op.dispatch.realtime_conversation_start" submission.id="019df3bd-65df-7ee2-8125-1d6701fe39d2" codex.op="realtime_conversation_start"}: codex_core::realtime_conversation: realtime conversation started ``` ### After the Change Logging commit (c8b00ac21a) ``` 2026-05-04T15:41:24.080363Z INFO ... codex_core::realtime_conversation: starting realtime conversation 2026-05-04T15:41:24.080434Z INFO ... codex_core::realtime_conversation: creating realtime call transport="webrtc" 2026-05-04T15:41:25.106906Z INFO ... codex_core::realtime_conversation: realtime call created; sdp answer ready transport="webrtc" call_id=rtc_u0_Dbpi8nhak5eLjQZ73yhAy elapsed_ms=1026 total_elapsed_ms=1026 2026-05-04T15:41:25.107067Z INFO ... codex_core::realtime_conversation: spawned realtime sideband connection task transport="webrtc" total_elapsed_ms=1026 2026-05-04T15:41:25.107160Z INFO ... codex_core::realtime_conversation: realtime conversation started 2026-05-04T15:41:25.107185Z INFO codex_core::realtime_conversation: connecting realtime sideband websocket call_id=rtc_u0_Dbpi8nhak5eLjQZ73yhAy 2026-05-04T15:41:25.107352Z INFO ... codex_core::realtime_conversation: sent realtime sdp answer to client 2026-05-04T15:41:26.076685Z INFO codex_core::realtime_conversation: connected realtime sideband websocket call_id=rtc_u0_Dbpi8nhak5eLjQZ73yhAy elapsed_ms=969 total_elapsed_ms=1996 2026-05-04T15:41:26.573893Z INFO codex_core::realtime_conversation: realtime session updated realtime_session_id=sess_u0_Dbpi8nhak5eLjQZ73yhAy 2026-05-04T15:41:26.573970Z INFO codex_core::realtime_conversation: received realtime conversation event event=SessionUpdated { ... } ``` ### Conclusion Here we see that we saved about a half a second in conversation startup (1532ms -> 969ms). This also checks out with my sanity tests; I was seeing at most a second of saving. --------- Co-authored-by: Codex <noreply@openai.com>
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
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.