Chrome for Testing pinned binary missing from versioned download endpoint

A repeatable development environment depends on Chrome for Testing remaining on a pinned build without auto-update. The distribution is published through versioned JSON endpoints that expose platform-specific download URLs, and teams often script those URLs into CI and local setup.

The unresolved behavior is whether an older pinned build remains available after newer releases ship. Google does not guarantee indefinite retention of every Chrome for Testing binary, and the JSON endpoints are not a formal API contract. The exact lag between Chrome for Testing and the stable release train is also undocumented.

Because of this, a pipeline pinned to a specific version may eventually fail to fetch the browser, breaking reproducibility without a clear migration path.

Does Google retain historical Chrome for Testing binaries indefinitely, or are older builds removed after a release window? Is there a documented minimum retention period or deprecation notice for pinned versions? How should teams verify long-term availability before committing to a specific Chrome for Testing version?