## Why
The SDK release workflow published the runtime before building the SDK, so an SDK build failure could leave the runtime published on its own.
## What changed
- Extract a reusable SDK build workflow that packages checked-in generated code and runs alongside runtime preparation. Require both builds before publishing the runtime, and verify runtime availability before publishing the SDK.
- Add `stage-sdk --codex-version` to set an explicit runtime dependency independently of the SDK version, retaining the checked-in pin by default and rejecting missing or duplicate pins.
- Accept Codex release tags in the runtime version resolver and use its normalized Python version for standalone runtime PyPI verification.
## Testing
Add coverage for wheel and source distribution metadata, preservation of checked-in code, independent beta SDK versions, runtime tag normalization, and invalid versions or dependency pins.
GitOrigin-RevId: feb572fadcf5d148814b26b480b4bae5ef6a39c5
## Why
Python SDK releases pin an exact `openai-codex-cli-bin` version, so all
eight platform runtime wheels must be available on PyPI before the SDK
package is built and published. PyPI does not support reusable workflows
as Trusted Publishers, which means OIDC-backed publishing must run from
each top-level release workflow.
## What changed
- add reusable `python-runtime-build.yml` to prepare and upload all
eight runtime wheels without publishing
- add top-level `python-runtime-release.yml` for manual runtime
publication before updating an SDK pin
- have `python-sdk-release.yml` publish and verify the prepared runtime
wheels from its own top-level trusted job before building the SDK
- verify PyPI exposes exactly the expected eight runtime wheels before
either release workflow continues
## PyPI configuration
- keep the trusted publisher for
`.github/workflows/python-sdk-release.yml` with environment `pypi`
- add a trusted publisher for
`.github/workflows/python-runtime-release.yml` with environment `pypi`
- no trusted publisher is needed for
`.github/workflows/python-runtime-build.yml`
## Validation
- parsed all three workflow YAML files
- validated all embedded shell blocks with `bash -n`
- no local tests run; relying on online CI