Michael Bolin
466798aa83
## Status This is the Bazel PR-CI cross-compilation follow-up to #20485. It is intentionally split from the Cargo/cargo-xwin release-build PoC so #20485 can stay as the historical release-build exploration. The unrelated async-utils test cleanup has been moved to #20686, so this PR is focused on the Windows Bazel CI path. The intended tradeoff is now explicit in `.github/workflows/bazel.yml`: pull requests get the fast Windows cross-compiled Bazel test leg, while post-merge pushes to `main` run both that fast cross leg and a fully native Windows Bazel test leg. The native main-only job keeps full V8/code-mode coverage and gets a 40-minute timeout because it is less latency-sensitive than PR CI. All other Bazel jobs remain at 30 minutes. ## Why Windows Bazel PR CI currently does the expensive part of the build on Windows. A native Windows Bazel test job on `main` completed in about 28m12s, leaving very little headroom under the 30-minute job timeout and making Windows the slowest PR signal. #20485 showed that Windows cross-compilation can be materially faster for Cargo release builds, but PR CI needs Bazel because Bazel owns our test sharding, flaky-test retries, and integration-test layout. This PR applies the same high-level shape we already use for macOS Bazel CI: compile with remote Linux execution, then run platform-specific tests on the platform runner. The compromise is deliberately signal-aware: code-mode/V8 changes are rare enough that PR CI can accept losing the direct V8/code-mode smoke-test signal temporarily, while `main` still runs the native Windows job post-merge to catch that class of regression. A follow-up PR should investigate making the cross-built Windows gnullvm V8 archive pass the direct V8/code-mode tests so this tradeoff can eventually go away. ## What Changed - Adds a `ci-windows-cross` Bazel config that targets `x86_64-pc-windows-gnullvm`, uses Linux RBE for build actions, and keeps `TestRunner` actions local on the Windows runner. - Adds explicit Windows platform definitions for `windows_x86_64_gnullvm`, `windows_x86_64_msvc`, and a bridge toolchain that lets gnullvm test targets execute under the Windows MSVC host platform. - Updates the Windows Bazel PR test leg to opt into the cross-compile path via `--windows-cross-compile` and `--remote-download-toplevel`. - Adds a `test-windows-native-main` job that runs only for `push` events on `refs/heads/main`, uses the native Windows Bazel path, includes V8/code-mode smoke tests, and has `timeout-minutes: 40`. - Keeps fork/community PRs without `BUILDBUDDY_API_KEY` on the previous local Windows MSVC-host fallback, including `--host_platform=//:local_windows_msvc` and `--jobs=8`. - Preserves the existing integration-test shape on non-gnullvm platforms, while generating Windows-cross wrapper targets only for `windows_gnullvm`. - Resolves `CARGO_BIN_EXE_*` values from runfiles at test runtime, avoiding hard-coded Cargo paths and duplicate test runfiles. - Extends the V8 Bazel patches enough for the `x86_64-pc-windows-gnullvm` target and Linux remote execution path. - Makes the Windows sandbox test cwd derive from `INSTA_WORKSPACE_ROOT` at runtime when Bazel provides it, because cross-compiled binaries may contain Linux compile-time paths. - Keeps the direct V8/code-mode unit smoke tests out of the Windows cross PR path for now while native Windows CI continues to cover them post-merge. ## Command Shape The fast Windows PR test leg invokes the normal Bazel CI wrapper like this: ```shell ./.github/scripts/run-bazel-ci.sh \ --print-failed-action-summary \ --print-failed-test-logs \ --windows-cross-compile \ --remote-download-toplevel \ -- \ test \ --test_tag_filters=-argument-comment-lint \ --test_verbose_timeout_warnings \ --build_metadata=COMMIT_SHA=${GITHUB_SHA} \ -- \ //... \ -//third_party/v8:all \ -//codex-rs/code-mode:code-mode-unit-tests \ -//codex-rs/v8-poc:v8-poc-unit-tests ``` With the BuildBuddy secret available on Windows, the wrapper selects `--config=ci-windows-cross` and appends the important Windows-cross overrides after rc expansion: ```shell --host_platform=//:rbe --shell_executable=/bin/bash --action_env=PATH=/usr/bin:/bin --host_action_env=PATH=/usr/bin:/bin --test_env=PATH=${CODEX_BAZEL_WINDOWS_PATH} ``` The native post-merge Windows job intentionally omits `--windows-cross-compile` and does not exclude the V8/code-mode unit targets: ```shell ./.github/scripts/run-bazel-ci.sh \ --print-failed-action-summary \ --print-failed-test-logs \ -- \ test \ --test_tag_filters=-argument-comment-lint \ --test_verbose_timeout_warnings \ --build_metadata=COMMIT_SHA=${GITHUB_SHA} \ --build_metadata=TAG_windows_native_main=true \ -- \ //... \ -//third_party/v8:all ``` ## Research Notes The existing macOS Bazel CI config already uses the model we want here: build actions run remotely with `--strategy=remote`, but `TestRunner` actions execute on the macOS runner. This PR mirrors that pattern for Windows with `--strategy=TestRunner=local`. The important Bazel detail is that `rules_rs` is already targeting `x86_64-pc-windows-gnullvm` for Windows Bazel PR tests. This PR changes where the build actions execute; it does not switch the Bazel PR test target to Cargo, `cargo-nextest`, or the MSVC release target. Cargo release builds differ from this Bazel path for V8: the normal Windows Cargo release target is MSVC, and `rusty_v8` publishes prebuilt Windows MSVC `.lib.gz` archives. The Bazel PR path targets `windows-gnullvm`; `rusty_v8` does not publish a prebuilt Windows GNU/gnullvm archive, so this PR builds that archive in-tree. That Linux-RBE-built gnullvm archive currently crashes in direct V8/code-mode smoke tests, which is why the workflow keeps native Windows coverage on `main`. The less obvious Bazel detail is test wrapper selection. Bazel chooses the Windows test wrapper (`tw.exe`) from the test action execution platform, not merely from the Rust target triple. The outer `workspace_root_test` therefore declares the default test toolchain and uses the bridge toolchain above so the test action executes on Windows while its inner Rust binary is built for gnullvm. The V8 investigation exposed a Windows-client gotcha: even when an action execution platform is Linux RBE, Bazel can still derive the genrule shell path from the Windows client. That produced remote commands trying to run `C:\Program Files\Git\usr\bin\bash.exe` on Linux workers. The wrapper now passes `--shell_executable=/bin/bash` with `--host_platform=//:rbe` for the Windows cross path. The same Windows-client/Linux-RBE boundary also affected `third_party/v8:binding_cc`: a multiline genrule command can carry CRLF line endings into Linux remote bash, which failed as `$'\r'`. That genrule now keeps the `sed` command on one physical shell line while using an explicit Starlark join so the shell arguments stay readable. ## Verification Local checks included: ```shell bash -n .github/scripts/run-bazel-ci.sh bash -n workspace_root_test_launcher.sh.tpl ruby -e "require %q{yaml}; YAML.load_file(%q{.github/workflows/bazel.yml}); puts %q{ok}" RUNNER_OS=Linux ./scripts/list-bazel-clippy-targets.sh RUNNER_OS=Windows ./scripts/list-bazel-clippy-targets.sh RUNNER_OS=Linux ./tools/argument-comment-lint/list-bazel-targets.sh RUNNER_OS=Windows ./tools/argument-comment-lint/list-bazel-targets.sh ``` The Linux clippy and argument-comment target lists contain zero `*-windows-cross-bin` labels, while the Windows lists still include 47 Windows-cross internal test binaries. CI evidence: - Baseline native Windows Bazel test on `main`: success in about 28m12s, https://github.com/openai/codex/actions/runs/25206257208/job/73907325959 - Green Windows-cross Bazel run on the split PR before adding the main-only native leg: Windows test 9m16s, Windows release verify 5m10s, Windows clippy 4m43s, https://github.com/openai/codex/actions/runs/25231890068 - The latest SHA adds the explicit PR-vs-main tradeoff in `bazel.yml`; CI is rerunning on that focused diff. ## Follow-Up A subsequent PR should investigate making a cross-built Windows binary work with V8/code-mode enabled. Likely options are either making the Linux-RBE-built `windows-gnullvm` V8 archive correct at runtime, or evaluating whether a Bazel MSVC target/toolchain can reuse the same prebuilt MSVC `rusty_v8` archive shape that Cargo release builds already use.
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.