The version header was set from WarpEngine::VERSION_HEADER, a constant introduced in the
same commit. The deploy that followed ran these controllers with an older `lib/`, so the
before_action raised NameError on every request and every engine endpoint answered 500 —
the catalog, the images, the file server and the config extension Woodpecker calls, which
is how it surfaced: a pipeline could no longer fetch its own configuration.
The controller now spells the header name out. A response header is not worth a dependency
that can take the API down when one half of a deploy is older than the other, and the
constant remains the documented name with a spec holding the two in step.
Confirmed in production mode against the same code that failed: 200 with the header.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>