## Why
The Windows release job installed DotSlash successfully, but package
archive creation still failed while writing `codex-package-*.tar.zst`.
The Python archiver used `shutil.which("zstd")`, which does not reliably
find the extensionless DotSlash manifest at `.github/workflows/zstd`
from native Windows Python.
That left release packaging dependent on a command named exactly `zstd`
being discoverable on `PATH`, even though the repository already carries
a DotSlash wrapper for Windows runners.
## What changed
- Add `resolve_zstd_command()` to prefer a real `zstd` binary when
present.
- Fall back to invoking `dotslash .github/workflows/zstd` when `zstd` is
not on `PATH`.
- Keep the error explicit when neither `zstd` nor the DotSlash fallback
is available.
- Add unit coverage for direct `zstd`, DotSlash fallback, and
missing-tool error paths.
## Verification
- `python3 -m unittest discover -s scripts/codex_package -p 'test_*.py'`
- `python3 -m py_compile scripts/codex_package/*.py`
## Why
Codex CLI packaging is currently split across npm staging, standalone
installers, and release bundle creation, which makes it hard to define
and validate a single valid package directory. This adds the first
standalone package builder so later release paths can converge on the
same canonical layout.
## What changed
- Added `scripts/build_codex_package.py` as the stable executable
wrapper around `scripts/codex_package`.
- Added modules for CLI parsing, target metadata, grouped cargo builds,
package layout validation, and archive writing.
- The builder creates a package directory with `codex-package.json`,
`bin/`, `codex-resources/`, and `codex-path`, and can serialize it as
`.tar.gz`, `.tar.zst`, or `.zip`.
- Source-built artifacts are built by one grouped `cargo build`: `codex`
for all targets, `bwrap` for Linux, and the Windows sandbox helpers for
Windows. `rg` remains an input because it is vendored from upstream
rather than built from this repo.
- Added `scripts/codex_package/README.md` to document the package
layout, source-built artifacts, and cargo profile behavior.
## Verification
- Ran wrapper/module syntax compilation.
- Ran `scripts/build_codex_package.py --help` from `/private/tmp`.
- Ran fake-cargo package/archive builds for macOS, Linux, and Windows
target layouts, including an assertion that generated tar archives
contain no duplicate member names.
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/23513).
* #23526
* __->__ #23513
