The engine now resolves transcripts store-first: a stored transcript —
including a stored SourceNone — is summarized without touching YouTube,
so re-analysis never re-fetches. On a miss it fetches through the source
(caption call still gated, ADR-014) and persists the terminal outcome for
the next analysis by any user. A transient SourceRateLimited is surfaced
to the runner for per-user backoff but never cached, so persistence can
never mask a 429 as a permanent "no transcript".
The TranscriptStore is optional (nil → fetch every time), keeping the
pure-core and scaffold wiring valid. cmd/tapir wires the store as both
summary sink and transcript cache, so `tapir run` and the web summarize
path (incl. paste + onboarding) all share the dedup.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
