Fetch a presigned job-output URL and describe what came back. Implementations
do NOT verify anything against the reference — the caller owns that comparison
so the policy (hard error on mismatch, never a silent fallback) lives in one
platform-neutral place and stays unit-testable with a fake downloader.
Fetch a presigned job-output URL and describe what came back. Implementations do NOT verify anything against the reference — the caller owns that comparison so the policy (hard error on mismatch, never a silent fallback) lives in one platform-neutral place and stays unit-testable with a fake downloader.