## Why
We already plan to remove the shell-tool MCP path, and doing that
cleanup first makes the follow-on `shell-escalation` work much simpler.
This change removes the last remaining reason to keep
`codex-rs/exec-server` around by moving the `codex-execve-wrapper`
binary and shared shell test fixtures to the crates/tests that now own
that functionality.
## What Changed
### Delete `codex-rs/exec-server`
- Remove the `exec-server` crate, including the MCP server binary,
MCP-specific modules, and its test support/test suite
- Remove `exec-server` from the `codex-rs` workspace and update
`Cargo.lock`
### Move `codex-execve-wrapper` into `codex-rs/shell-escalation`
- Move the wrapper implementation into `shell-escalation`
(`src/unix/execve_wrapper.rs`)
- Add the `codex-execve-wrapper` binary entrypoint under
`shell-escalation/src/bin/`
- Update `shell-escalation` exports/module layout so the wrapper
entrypoint is hosted there
- Move the wrapper README content from `exec-server` to
`shell-escalation/README.md`
### Move shared shell test fixtures to `app-server`
- Move the DotSlash `bash`/`zsh` test fixtures from
`exec-server/tests/suite/` to `app-server/tests/suite/`
- Update `app-server` zsh-fork tests to reference the new fixture paths
### Keep `shell-tool-mcp` as a shell-assets package
- Update `.github/workflows/shell-tool-mcp.yml` packaging so the npm
artifact contains only patched Bash/Zsh payloads (no Rust binaries)
- Update `shell-tool-mcp/package.json`, `shell-tool-mcp/src/index.ts`,
and docs to reflect the shell-assets-only package shape
- `shell-tool-mcp-ci.yml` does not need changes because it is already
JS-only
## Verification
- `cargo shear`
- `cargo clippy -p codex-shell-escalation --tests`
- `just clippy`
When running `npx @openai/codex-shell-tool-mcp`, the old code derived
`__dirname` from `process.argv[1]`, which points to npx’s transient
wrapper script in
`~/.npm/_npx/134d0fb7e1a27652/node_modules/.bin/codex-shell-tool-mcp`.
That made `vendorRoot` resolve to `<npx cache>/vendor`, so the startup
checks failed with "Required binary missing" because it looked for
`codex-execve-wrapper` in the wrong place.
By relying on the real module `__dirname` and `path.resolve(__dirname,
"..", "vendor")`, the package now anchors to its installed location
under `node_modules/@openai/codex-shell-tool-mcp/`, so the bundled
binaries are found and npx launches correctly.
This adds a GitHub workflow for building a new npm module we are
experimenting with that contains an MCP server for running Bash
commands. The new workflow, `shell-tool-mcp`, is a dependency of the
general `release` workflow so that we continue to use one version number
for all artifacts across the project in one GitHub release.
`.github/workflows/shell-tool-mcp.yml` is the primary workflow
introduced by this PR, which does the following:
- builds the `codex-exec-mcp-server` and `codex-execve-wrapper`
executables for both arm64 and x64 versions of Mac and Linux (preferring
the MUSL version for Linux)
- builds Bash (dynamically linked) for a [comically] large number of
platforms (both x64 and arm64 for most) with a small patch specified by
`shell-tool-mcp/patches/bash-exec-wrapper.patch`:
- `debian-11`
- `debian-12`
- `ubuntu-20.04`
- `ubuntu-22.04`
- `ubuntu-24.04`
- `centos-9`
- `macos-13` (x64 only)
- `macos-14` (arm64 only)
- `macos-15` (arm64 only)
- builds the TypeScript for the [new] Node module declared in the
`shell-tool-mcp/` folder, which creates `bin/mcp-server.js`
- adds all of the native binaries to `shell-tool-mcp/vendor/` folder;
`bin/mcp-server.js` does a runtime check to determine which ones to
execute
- uses `npm pack` to create the `.tgz` for the module
- if `publish: true` is set, invokes the `npm publish` call with the
`.tgz`
The justification for building Bash for so many different operating
systems is because, since it is dynamically linked, we want to increase
our confidence that the version we build is compatible with the glibc
whatever OS we end up running on. (Note this is less of a concern with
`codex-exec-mcp-server` and `codex-execve-wrapper` on Linux, as they are
statically linked.)
This PR also introduces the code for the npm module in `shell-tool-mcp/`
(the proposed module name is `@openai/codex-shell-tool-mcp`). Initially,
I intended the module to be a single file of vanilla JavaScript (like
[`codex-cli/bin/codex.js`](https://github.com/openai/codex/blob/ab5972d447da78d3e4dd8461cf7d43a22e5d2acb/codex-cli/bin/codex.js)),
but some of the logic seemed a bit tricky, so I decided to port it to
TypeScript and add unit tests.
`shell-tool-mcp/src/index.ts` defines the `main()` function for the
module, which performs runtime checks to determine the clang triple to
find the path to the Rust executables within the `vendor/` folder
(`resolveTargetTriple()`). It uses a combination of `readOsRelease()`
and `resolveBashPath()` to determine the correct Bash executable to run
in the environment. Ultimately, it spawns a command like the following:
```
codex-exec-mcp-server \
--execve codex-execve-wrapper \
--bash custom-bash "$@"
```
Note `.github/workflows/shell-tool-mcp-ci.yml` defines a fairly standard
CI job for the module (`format`/`build`/`test`).
To test this PR, I pushed this branch to my personal fork of Codex and
ran the CI job there:
https://github.com/bolinfest/codex/actions/runs/19564311320
Admittedly, the graph looks a bit wild now:
<img width="5115" height="2969" alt="Screenshot 2025-11-20 at 11 44
58 PM"
src="https://github.com/user-attachments/assets/cc5ef306-efc1-4ed7-a137-5347e394f393"
/>
But when it finished, I was able to download `codex-shell-tool-mcp-npm`
from the **Artifacts** for the workflow in an empty temp directory,
unzip the `.zip` and then the `.tgz` inside it, followed by `xattr -rc
.` to remove the quarantine bits. Then I ran:
```shell
npx @modelcontextprotocol/inspector node /private/tmp/foobar4/package/bin/mcp-server.js
```
which launched the MCP Inspector and I was able to use it as expected!
This bodes well that this should work once the package is published to
npm:
```shell
npx @modelcontextprotocol/inspector npx @openai/codex-shell-tool-mcp
```
Also, to verify the package contains what I expect:
```shell
/tmp/foobar4/package$ tree
.
├── bin
│ └── mcp-server.js
├── package.json
├── README.md
└── vendor
├── aarch64-apple-darwin
│ ├── bash
│ │ ├── macos-14
│ │ │ └── bash
│ │ └── macos-15
│ │ └── bash
│ ├── codex-exec-mcp-server
│ └── codex-execve-wrapper
├── aarch64-unknown-linux-musl
│ ├── bash
│ │ ├── centos-9
│ │ │ └── bash
│ │ ├── debian-11
│ │ │ └── bash
│ │ ├── debian-12
│ │ │ └── bash
│ │ ├── ubuntu-20.04
│ │ │ └── bash
│ │ ├── ubuntu-22.04
│ │ │ └── bash
│ │ └── ubuntu-24.04
│ │ └── bash
│ ├── codex-exec-mcp-server
│ └── codex-execve-wrapper
├── x86_64-apple-darwin
│ ├── bash
│ │ └── macos-13
│ │ └── bash
│ ├── codex-exec-mcp-server
│ └── codex-execve-wrapper
└── x86_64-unknown-linux-musl
├── bash
│ ├── centos-9
│ │ └── bash
│ ├── debian-11
│ │ └── bash
│ ├── debian-12
│ │ └── bash
│ ├── ubuntu-20.04
│ │ └── bash
│ ├── ubuntu-22.04
│ │ └── bash
│ └── ubuntu-24.04
│ └── bash
├── codex-exec-mcp-server
└── codex-execve-wrapper
26 directories, 26 files
```
Michael Bolin ·