## Why
This is the final PR in the Windows fs-helper sandbox stack and contains
the actual bug fix.
The exec-server filesystem helper is a direct-spawn path: it asks
`SandboxManager` for a `SandboxExecRequest`, then launches the returned
argv itself. That works on macOS and Linux because the transformed argv
is already a self-contained sandbox wrapper. On Windows, the transformed
request carried `WindowsRestrictedToken` metadata, but the direct-spawn
fs-helper runner still launched the helper argv directly.
That means Windows filesystem built-ins backed by the fs-helper could
run with the parent Codex process permissions instead of the configured
Windows sandbox. This PR makes the direct-spawn transform produce a
self-contained Windows wrapper argv before fs-helper launches it.
## What Changed
- Added `SandboxManager::transform_for_direct_spawn()` for callers that
launch the returned argv themselves.
- Wrapped Windows restricted-token direct-spawn requests with `codex.exe
--run-as-windows-sandbox` and then marked the outer request as
unsandboxed, matching the macOS/Linux wrapper argv shape.
- Updated `exec-server/src/fs_sandbox.rs` to use the direct-spawn
transform for fs-helper launches.
- Materialized the inner `codex.exe --codex-run-as-fs-helper` executable
into `.sandbox-bin` so the sandboxed user can run it.
- Carried runtime workspace roots through `FileSystemSandboxContext` as
`PathUri` values so `:workspace_roots` policies resolve correctly
without sending native client paths over exec-server JSON.
- Preserved wrapper setup identity environment needed by Windows sandbox
setup without changing the serialized inner helper environment.
## Verification
- `just bazel-lock-update`
- `just bazel-lock-check`
- `just test -p codex-sandboxing transform_for_direct_spawn_windows`
- `just test -p codex-exec-server fs_sandbox::tests`
- `just fix -p codex-windows-sandbox -p codex-sandboxing -p
codex-exec-server -p codex-core -p codex-file-system`
Local note: `just fmt` completed Rust formatting, but this workstation
still fails the non-Rust formatter phases because uv cannot open its
cache and the local buildifier/dotslash path is missing.
## Why
A Mac Bazel run hit a flake in
`server::handler::tests::output_and_exit_are_retained_after_notification_receiver_closes`
where the read path observed process exit but lost the expected buffered
stdout (`first\nsecond\n`). See the [GitHub Actions
job](https://github.com/openai/codex/actions/runs/24758468552/job/72436716505)
and [BuildBuddy
invocation](https://app.buildbuddy.io/invocation/37475a12-4ef2-45fb-ab8a-e49a2aba1d59).
The underlying race is that process exit is not the same thing as
stdout/stderr closure. If a child or grandchild inherits the pipe write
end, or a process duplicates it with `dup2`, the watched process can
exit while the stream is still open and more output can still arrive.
The exec-server was starting exited-process retention cleanup from the
exit event, so the process entry could be removed before the output
streams had actually closed.
While stress-testing the exec-server unit suite,
`server::handler::tests::long_poll_read_fails_after_session_resume`
exposed a separate test race: it started a short-lived command that
could exit and wake the pending long-poll read before the session-resume
assertion observed the resumed-session error. That test is intended to
cover resume eviction, not process-exit delivery, so this change keeps
the process alive and quiet while the second connection resumes the
session.
## What changed
- Keep exec-server process entries retained until stdout/stderr streams
close, then start the post-exit retention timer from the closed event.
- Wake long-poll readers when the closed event is emitted.
- Add focused `local_process` unit coverage that proves late output is
still retained after the short test retention interval has elapsed, and
that closed process entries are eventually evicted.
- Add a local and remote regression test where a parent exits while a
child keeps inherited stdout open. The child waits on an explicit
release file, so the test deterministically observes exit first,
releases the child, then requires a nonzero-wait read from the exit
sequence to receive the late output.
- In `codex-rs/exec-server/src/server/handler/tests.rs`, make
`long_poll_read_fails_after_session_resume` run a long-lived silent
command instead of a short command that prints and exits. This isolates
the test to session-resume behavior and prevents a normal process exit
from satisfying the pending long-poll read first.
## Testing
- `cargo test -p codex-exec-server
exec_process_retains_output_after_exit_until_streams_close`
- `cargo test -p codex-exec-server local_process::tests`
- `cargo test -p codex-exec-server`
- `just fix -p codex-exec-server`
- `bazel test //codex-rs/exec-server:exec-server-unit-tests
//codex-rs/exec-server:exec-server-exec_process-test
//codex-rs/exec-server:exec-server-file_system-test
//codex-rs/exec-server:exec-server-http_client-test
//codex-rs/exec-server:exec-server-initialize-test
//codex-rs/exec-server:exec-server-process-test
//codex-rs/exec-server:exec-server-websocket-test`
- `bazel test --runs_per_test=25
//codex-rs/exec-server:exec-server-unit-tests`
## Documentation
No docs update needed; this is an internal exec-server correctness fix.
## Summary\n- add an exec-server package-local test helper binary that
can run exec-server and fs-helper flows\n- route exec-server filesystem
tests through that helper instead of cross-crate codex helper
binaries\n- stop relying on Bazel-only extra binary wiring for these
tests\n\n## Testing\n- not run (per repo guidance for codex changes)
---------
Co-authored-by: Codex <noreply@openai.com>
Summary
- delete the deprecated stdio transport plumbing from the exec server
stack
- add a basic `exec_server()` harness plus test utilities to start a
server, send requests, and await events
- refresh exec-server dependencies, configs, and documentation to
reflect the new flow
Testing
- Not run (not requested)
---------
Co-authored-by: starr-openai <starr@openai.com>
Co-authored-by: Codex <noreply@openai.com>
iceweasel-oai ·
Michael Bolin ·
starr-openai ·
pakrym-oai ·