Capture the ADR-021 promise as a mapped BDD scenario: re-analyzing a
stored video reads the stored transcript and does not fetch captions.
Since paste-a-URL and the onboarding burst summarize through the same
engine chokepoint (resolveTranscript, store-first), this one scenario
covers their reuse path too — there is exactly one gated caption entry
point (youtube.FetchTranscript → WaitFetchGate) and one engine caller in
front of it, so the dedup is structural, not per-feature.
Mapped to TestProcessNewVideo_SecondSummarizeDoesNotRefetch.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>